title: Emergent Universe and Phantom Tachyon Model

abstract:
  In this work, I have considered that the universe is filled with normal
matter and phantom field (or tachyonic field). If the universe is filled with
scalar field, Ellis et al have shown that emergent scenario is possible only
for $k=+1$ i.e. for closed universe and here I have shown that the emergent
scenario is possible for closed universe if the universe contains normal
tachyonic field. But for phantom field (or tachyonic field), the negative
kinetic term can generate the emergent scenario for all values of $k ~(=0,\pm
1)$. From recently developed statefinder parameters, the behaviour of different
stages of the evolution of the emergent universe have been studied. The static
Einstein universe and the stability analysis have been briefly discussed for
both phantom and tachyon models.


title: Hamiltonian statistical mechanics

abstract:
  A framework for statistical-mechanical analysis of quantum Hamiltonians is
introduced. The approach is based upon a gradient flow equation in the space of
Hamiltonians such that the eigenvectors of the initial Hamiltonian evolve
toward those of the reference Hamiltonian. The nonlinear double-bracket
equation governing the flow is such that the eigenvalues of the initial
Hamiltonian remain unperturbed. The space of Hamiltonians is foliated by
compact invariant subspaces, which permits the construction of statistical
distributions over the Hamiltonians. In two dimensions, an explicit dynamical
model is introduced, wherein the density function on the space of Hamiltonians
approaches an equilibrium state characterised by the canonical ensemble. This
is used to compute quenched and annealed averages of quantum observables.


title: On finite-index extensions of subgroups of free groups

abstract:
  We study the lattice of finite-index extensions of a given finitely generated
subgroup $H$ of a free group $F$. This lattice is finite and we give a
combinatorial characterization of its greatest element, which is the
commensurator of $H$. This characterization leads to a fast algorithm to
compute the commensurator, which is based on a standard algorithm from automata
theory. We also give a sub-exponential and super-polynomial upper bound for the
number of finite-index extensions of $H$, and we give a language-theoretic
characterization of the lattice of finite-index subgroups of $H$. Finally, we
give a polynomial time algorithm to compute the malnormal closure of $H$.


title: Mixing of Quantum Walks on Generalized Hypercubes

abstract:
  We study continuous-time quantum walks on graphs which generalize the
hypercube. The only known family of graphs whose quantum walk instantaneously
mixes to uniform is the Hamming graphs with small arities. We show that quantum
uniform mixing on the hypercube is robust under the addition of perfect
matchings but not much else. Our specific results include:
  (1) The graph obtained by augmenting the hypercube with an additive matching
is instantaneous uniform mixing whenever the parity of the matching is even,
but with a slower mixing time. This strictly includes Moore-Russell's result on
the hypercube.
  (2) The class of Hamming graphs is not uniform mixing if and only if its
arity is greater than 5. This is a tight characterization of quantum uniform
mixing on Hamming graphs; previously, only the status of arity less than 5 was
known.
  (3) The bunkbed graph B(A[f]), defined by a hypercube-circulant matrix A and
a Boolean function f, is not uniform mixing if the Fourier transform of f has
small support. This explains why the hypercube is uniform mixing and why the
join of two hypercubes is not.


title: How to Draw Tropical Planes

abstract:
  The tropical Grassmannian parameterizes tropicalizations of linear spaces,
while the Dressian parameterizes all planes in $\TP^{n-1}$. We study these
parameter spaces and we compute them explicitly for $n \leq 7$. Planes are
identified with matroid subdivisions and with arrangements of trees. These
representations are used to draw pictures.


title: Sound waves in the intracluster medium of the Centaurus cluster

abstract:
  We report the discovery of ripple-like X-ray surface brightness oscillations
in the core of the Centaurus cluster of galaxies, found with 200 ks of Chandra
observations. The features are between 3 to 5 per cent variations in surface
brightness with a wavelength of around 9 kpc. If, as has been conjectured for
the Perseus cluster, these are sound waves generated by the repetitive
inflation of central radio bubbles, they represent around 5x10^42 erg/s of
spherical sound-wave power at a radius of 30 kpc. The period of the waves would
be 10^7 yr. If their power is dissipated in the core of the cluster, it would
balance much of the radiative cooling by X-ray emission, which is around
1.3x10^43 erg/s within the inner 30 kpc. The power of the sound waves would be
a factor of four smaller that the heating power of the central radio bubbles,
which means that energy is converted into sound waves efficiently.


title: On the nature of unabsorbed Seyfert 2 galaxies

abstract:
  We present an analysis of six 12 um selected Seyfert 2 galaxies that have
been reported to be unabsorbed in the X-ray. By comparing the luminosities of
these galaxies in the mid-IR (12um), optical ([O III]) and hard X-ray (2-10
keV), we show that they are all under-luminous in the 2-10 keV X-ray band. Four
of the objects exhibit X-ray spectra indicative of a hard excess, consistent
with a heavily obscured X-ray component and hence a hidden nucleus. In these
objects the softer X-rays may be dominated by a strong soft scattered continuum
or contamination from the host galaxy, which is responsible for the unabsorbed
X-ray spectra observed, and accounts for the anomalously low 2-10 keV X-ray
luminosity. We confirm this assertion in NGC4501 with a Chandra observation,
which shows hard X-ray emission coincident with the nucleus, consistent with
heavy absorption, and a number of contaminating softer sources which account
for the bulk of the softer emission. We point out that such 'Compton thick'
sources need not necessarily present iron Ka emission of high EW. An example in
our sample is IRASF01475-0740, which we know must host an obscured AGN as it
hosts a HBLR seen in scattered light (Tran 2003). The X-ray spectrum is
nonetheless relatively unobscured and the iron Ka line only moderate in
strength. These observations can be reconciled if the hidden nuclear emission
is dominated by transmitted, rather than reflected X-rays, which can then be
weak compared to the soft scattered light or galactic emission. Despite these
considerations, we conclude that NGC3147 & 3660 may intrinsically lack a BLR,
confirming the recent results of Bianchi et al. (2008) for NGC3147. Neither
X-ray spectrum shows signs of hidden hard emission and both sources exhibit
X-ray variability leading us to believe we are viewing the nucleus directly.


title: TW Hydrae: evidence of stellar spots instead of a Hot Jupiter

abstract:
  TW Hydrae shows significant radial-velocity variations in the optical regime.
They have been attributed to a 10 Jupiter Mass planet orbiting the star at 0.04
AU. In this work, we have tested whether the observed RV variations can be
caused by stellar spots. We have also analyzed new optical and infrared data to
confirm the signal of the planet companion. We fitted the RV variations of TW
Hya using a cool spot model. Our model shows that a cold spot covering 7% of
the stellar surface and located at a latitude of 54 deg can reproduce the
reported RV variations. The model also predicts a bisector semi-amplitude
variation <10 m/s, which is less than the errors of the RV measurements
discussed in an earlier publication. The analysis of new optical RV data, with
typical errors of 10 m/s, shows a larger RV amplitude that varies depending on
the correlation mask used. A slight correlation between the RV variation and
the bisector is also observed, although not at a very significant level. The
infrared H-band RV curve is almost flat, showing a small variation (<35 m/s)
that is not consistent with the optical orbit. All these results support the
spot scenario rather than the presence of a hot Jupiter around TW Hya.


title: Simulations of a supersymmetry inspired model on a fuzzy sphere

abstract:
  We present a numerical study of a two dimensional model of the Wess-Zumino
type. We formulate this model on a sphere, where the fields are expanded in
spherical harmonics. The sphere becomes fuzzy by a truncation in the angular
momenta. This leads to a finite set of degrees of freedom without explicitly
breaking the space symmetries. The corresponding field theory is expressed in
terms of a matrix model, which can be simulated. We present first numerical
results for the phase structure of a variant of this model on a fuzzy sphere.
The prospect to restore exact supersymmetry in certain limits is under
investigation.


title:
Signatures of Universal Characteristics of Fractal Fluctuations in
  Global Mean Monthly Temperature Anomalies

abstract:
  Selfsimilar space-time fractal fluctuations are generic to dynamical systems
in nature such as atmospheric flows, heartbeat patterns, population dynamics,
etc. The physics of the long-range correlations intrinsic to fractal
fluctuations is not yet identified. It is important to quantify the physics
underlying the irregular fractal fluctuations for predictability studies. A
general systems theory for fractals visualizes the emergence of successively
larger scale fluctuations to result from the space-time integration of enclosed
smaller scale fluctuations. The model predictions are as follows. The
probability distribution and the power spectrum for fractal fluctuations is the
same inverse power law function incorporating the golden mean. The predicted
distribution is close to the Gaussian distribution for small-scale fluctuations
but exhibits fat long tail for large-scale fluctuations with higher probability
of occurrence than predicted by Gaussian distribution. Since the power
(variance i.e. square of eddy amplitude) spectrum also represents the
probability densities as in the case of quantum systems such as the electron or
photon, fractal fluctuations exhibit quantumlike chaos. The fine structure
constant for spectrum of fractal fluctuations is a function of the golden mean
and is analogous to atomic spectra equal to about 1/137. Global gridded time
series data sets of monthly mean temperatures for the period 1880 - 2007/2008
are analysed to show that data sets and corresponding power spectra exhibit
distributions close to the model predicted inverse power law distribution. The
model predicted and observed universal spectrum for interannual variability
rules out linear secular trends in global monthly mean temperatures. Global
warming results in intensification of fluctuations of all scales and manifested
immediately in high frequency fluctuations.


title: The GSI anomaly

abstract:
  Recently, an experiment at GSI Darmstadt has observed oscillating decay rates
of heavy ions. Several controversial attempts have been made to explain this
effect in terms of neutrino mixing. We briefly describe the experimental
results, give an overview of the literature, and show that the effect cannot be
due to neutrino mixing. If the effect survives, it could, however, be explained
by hypothetical internal excitations of the mother ions (~ 10^(-15) eV).


title: Weighted Hardy and singular operators in Morrey spaces

abstract:
  We study the weighted boundedness of the Cauchy singular integral operator
$S_\Gm$ in Morrey spaces $L^{p,\lambda}(\Gm)$ on curves satisfying the
arc-chord condition, for a class of "radial type" almost monotonic weights. The
non-weighted boundedness is shown to hold on an arbitrary Carleson curve. We
show that the weighted boundedness is reduced to the boundedness of weighted
Hardy operators in Morrey spaces $L^{p,\lambda}(0,\ell), \ell>0$. We find
conditions for weighted Hardy operators to be bounded in Morrey spaces. To
cover the case of curves we also extend the boundedness of the Hardy-Littlewood
maximal operator in Morrey spaces, known in the Euclidean setting, to the case
of Carleson curves.
  Key words and phrases: Morrey space, singular operator, Hardy operator,
Hardy-Littlewood maximal operator, weighted estimate.


title:
Star formation rates in Lyman break galaxies: radio stacking of LBGs in
  the COSMOS field and the sub-$\mu$Jy radio source population

abstract:
  We present an analysis of the radio properties of large samples of Lyman
Break Galaxies (LBGs) at $z \sim 3$, 4, and 5 from the COSMOS field. The median
stacking analysis yields a statistical detection of the $z \sim 3$ LBGs (U-band
drop-outs), with a 1.4 GHz flux density of $0.90 \pm 0.21 \mu$Jy. The stacked
emission is unresolved, with a size $< 1"$, or a physical size $< 8$kpc. The
total star formation rate implied by this radio luminosity is $31\pm 7$
$M_\odot$ year$^{-1}$, based on the radio-FIR correlation in low redshift star
forming galaxies. The star formation rate derived from a similar analysis of
the UV luminosities is 17 $M_\odot$ year$^{-1}$, without any correction for UV
dust attenuation. The simplest conclusion is that the dust attenuation factor
is 1.8 at UV wavelengths. However, this factor is considerably smaller than the
standard attenuation factor $\sim 5$, normally assumed for LBGs. We discuss
potential reasons for this discrepancy, including the possibility that the dust
attenuation factor at $z \ge 3$ is smaller than at lower redshifts. Conversely,
the radio luminosity for a given star formation rate may be systematically
lower at very high redshift. Two possible causes for a suppressed radio
luminosity are: (i) increased inverse Compton cooling of the relativistic
electron population due to scattering off the increasing CMB at high redshift,
or (ii) cosmic ray diffusion from systematically smaller galaxies. The radio
detections of individual sources are consistent with a radio-loud AGN fraction
of 0.3%. One source is identified as a very dusty, extreme starburst galaxy (a
'submm galaxy').


title:
Upper critical field, anisotropy, and superconducting properties of
  Ba$_{1-x}$K$_x$Fe$_2$As$_2$ single crystals

abstract:
  The temperature dependent resistivity of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ (x =
0.23, 0.25, 0.28 and 0.4) single crystals and the angle dependent resistivity
of superconducting Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ single crystals were
measured in magnetic fields up to 9 T. The measurements of temperature
dependent resistivity for samples with different doping levels revealed very
high upper critical fields which increase with the transition temperature
monotonously, and a very low superconducting anisotropy ratio
$\Gamma=H_{c2}^{ab}/H_{c2}^c \approx$ 2. By scaling the resistivity in the
frame of the anisotropic Ginzburg-Landau theory, the angle dependent
resistivity of the Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ single crystal measured with
different magnetic fields at a certain temperature collapsed onto one curve. As
the only scaling parameter, the anisotropy $\Gamma$ was determined
alternatively for each temperature and was found to be between two and three.


title: Fat-Tailed Distributions and Levy Processes

abstract:
  The notion that natural disasters can be controlled is, of course, farcical;
history is permeated with examples of countless failed attempts at this
pointless task; it is synonymous with trying to build a perpetual motion
machine. Nonetheless, there are ways to reduce their impact on human
communities, particularly by looking away from the normal hypothesis.


title:
Electronic Structure of Noncentrosymmetric Superconductor
  Li$_2$(Pd$_x$Pt$_{1-x}$3)B Studied by Photoemission Spectroscopy

abstract:
  We have performed x-ray photoemission spectroscopy on the system of
noncentrosymmetric superconductor, Li$_2$(Pd$_x$Pt$_{1-x}$3)B. For
Li$_2$Pt$_3$B, we found 2 major peaks with 2 other weak components, and the
band calculations were in agreement with the observation. The assignment of
valence band features using the calculated partial density of states determined
that Pt 5d and B 2p contribute to the density of states at the Fermi level. The
effect of antisymmetric spin-orbit coupling on the band structure might have
been probed, and the analysis on the effect of Pt incorporation into the system
indicates the smooth evolution of electronic structures. We presented the
measurements of core levels (Pd 3d, Pt 4f, and B 1s) and discussed the chemical
bonding states and electronic structures from them.


title: Rankin's method and Jacobi forms of several variables

abstract:
  Following Rankin's method, D. Zagier computed the $n$-th Rankin-Cohen bracket
of a modular form $g$ of weight $k_1$ with the Eisenstein series of weight
$k_2$ and then computed the inner product of this Rankin-Cohen bracket with a
cusp form $f$ of weight $k = k_1+k_2+2n$ and showed that this inner product
gives, upto a constant, the special value of the Rankin-Selberg convolution of
$f$ and $g$. This result was generalized to Jacobi forms of degree 1 by Y.
Choie and W. Kohnen. In this paper, we generalize this result to Jacobi forms
defined over ${\mathcal H} \times {\mathbb C}^{(g, 1)}$.


title: Non Abelian Vortices as Instantons on Noncommutative Discrete Space

abstract:
  There seems to be close relationship between the moduli space of vortices and
the moduli space of instantons, which is not yet clearly understood from a
standpoint of the field theory. We clarify the reasons why many similarities
are found in the methods for constructing the moduli of instanton and vortex,
viewed in the light of the notion of the self-duality. We show that the
non-Abelian vortex is nothing but the instanton in $R^{2} \times Z_{2}$ from a
viewpoint of the noncommutative differential geometry and the gauge theory in
discrete space. The action for pure Yang-Mills theory in $R^{2} \times Z_{2}$
is equivalent to that for Yang-Mills-Higgs theory in $R^{2} $.


title:
Target mass corrections for spin-dependent structure functions in
  collinear factorization

abstract:
  We derive target mass corrections (TMC) for the spin-dependent nucleon
structure function g1 and polarization asymmetry A1 in collinear factorization
at leading twist. The TMCs are found to be significant for g1 at large xB, even
at relatively high Q^2 values, but largely cancel in A1. A comparison of TMCs
obtained from collinear factorization and from the operator product expansion
shows that at low Q^2 the corrections drive the proton A1 in opposite
directions.


title: Morphological Phases of Crumpled Wire

abstract:
  We find that in two dimensions wires can crumple into different morphologies
and present the associated morphological phase diagram. Our results are based
on experiments with different metallic wires and confirmed by numerical
simulations using a discrete element model. We show that during crumpling, the
number of loops increases according to a power-law with different exponents in
each morphology. Furthermore, we observe a power-law divergence of the
structure's bulk stiffness similar to what is observed in forced crumpling of
membranes.


title: Gluelump model with transverse constituent gluons

abstract:
  We show that C-odd gluelumps can be successfully described as bound states of
a single transverse constituent gluon evolving in the flux-tube-like potential
generated by a static color-octet source. The use of a helicity degree of
freedom rather than a spin one for the constituent gluon forbids the states
that are not observed in lattice QCD. Our model leads to a gluelump mass
spectrum in remarkable agreement with the available lattice data provided that
an additional parity-splitting mass term is introduced. We argue that such a
term is due to instanton-induced interactions in gluelumps.


title: Phonon distributions of a single bath mode coupled to a quantum dot

abstract:
  The properties of an unconventional, single mode phonon bath coupled to a
quantum dot, are investigated within the rotating wave approximation. The
electron current through the dot induces an out of equilibrium bath, with a
phonon distribution qualitatively different from the thermal one. In selected
transport regimes, such a distribution is characterized by a peculiar selective
population of few phonon modes and can exhibit a sub-Poissonian behavior. It is
shown that such a sub-Poissonian behavior is favored by a double occupancy of
the dot. The crossover from a unequilibrated to a conventional thermal bath is
explored, and the limitations of the rotating wave approximation are discussed.


title:
The puzzle of magnetic resonance effect on the magnetic compass of
  migratory birds

abstract:
  Experiments on the effect of radio-frequency (RF) magnetic fields on the
magnetic compass orientation of migratory birds are analyzed using the theory
of magnetic resonance. The results of these experiments were earlier
interpreted within the radical-pair model of magnetoreception. However, the
consistent analysis shows that the amplitudes of the RF fields used are far too
small to noticeably influence electron spins in organic radicals. Other
possible agents that could mediate the birds' response to the RF fields are
discussed, but apparently no known physical system can be responsible for this
effect.


title: Spin transport of indirect excitons in GaAs coupled quantum wells

abstract:
  Spin transport of indirect excitons in GaAs/AlGaAs coupled quantum wells was
observed by measuring the spatially resolved circular polarization of the
exciton emission. The exciton spin transport originates from the long spin
relaxation time and long lifetime of the indirect excitons.


title: Phase Shift Sequences for an Adding Interferometer

abstract:
  Cosmic microwave background (CMB) polarimetry has the potential to provide
revolutionary advances in cosmology. Future experiments to detect the very weak
B mode signal in CMB polarization maps will require unprecedented sensitivity
and control of systematic errors. Bolometric interferometry may provide a way
to achieve these goals. In a bolometric interferometer (or other adding
interferometer), phase shift sequences are applied to the inputs in order to
recover the visibilities. Noise is minimized when the phase shift sequences
corresponding to all visibilities are orthogonal. We present a systematic
method for finding sequences that produce this orthogonality, approximately
minimizing both the length of the time sequence and the number of discrete
phase shift values required. When some baselines are geometrically equivalent,
we can choose sequences that read out those baselines simultaneously, which has
been shown to improve signal to noise ratio.


title: The Infrared Luminosity of Galaxy Clusters

abstract:
  The aim of this study is to quantify the infrared luminosity of clusters as a
function of redshift and compare this with the X-ray luminosity. This can
potentially constrain the origin of the infrared emission to be intracluster
dust and/or dust heated by star formation in the cluster galaxies. We perform a
statistical analysis of a large sample of galaxy clusters selected from
existing databases and catalogues.We coadd the infrared IRAS and X-ray RASS
images in the direction of the selected clusters within successive redshift
intervals up to z = 1. We find that the total infrared luminosity is very high
and on average 20 times higher than the X-ray luminosity. If all the infrared
luminosity is to be attributed to emission from diffuse intracluster dust, then
the IR to X-ray ratio implies a dust-to-gas mass abundance of 5e-4. However,
the infrared luminosity shows a strong enhancement for 0.1 < z < 1, which
cannot be attributed to cluster selection effects. We show that this
enhancement is compatible with a star formation rate in the member galaxies
that is typical of the central Mpc of the Coma cluster at z = 0 and evolves
with the redshift as (1+z)^5. It is likely that most of the infrared luminosity
that we measure is generated by the ongoing star formation in the member
galaxies. From theoretical predictions calibrated on extinction measurements
(dust mass abundance equal to 1e-5), we expect only a minor contribution, of a
few percent, from intracluster dust.


title: Alpha-Cluster States Populated in 24Mg+12C

abstract:
  Charged particle and gamma decays in light alpha-like nuclei are investigated
for 24Mg+12C. Various theoretical predictions for the occurence of
superdeformed and hyperdeformed bands associated with resonance structures with
low spin are presented. The inverse kinematics reaction 24Mg+12C is studied at
Elab(24Mg) = 130 MeV. Exclusive data were collected with the Binary Reaction
Spectrometer in coincidence with EUROBALL IV installed at the VIVITRON Tandem
facility at Strasbourg. Specific structures with large deformation were
selectively populated in binary reactions and their associated gamma decays
studied. Coincident events from $\alpha$-transfer channels were selected by
choosing the excitation energy or the entry point via the two-body Q-values.
The analysis of the binary reaction channels is presented with a particular
emphasis on 20Ne-gamma and 16O-gamma coincidences.


title:
Quantum teleportation via a two-qubit Heisenberg XXZ chain-effects of
  anisotropy and magnetic field

abstract:
  We study quantum teleportation via a two-qubit Heisenberg XXZ chain under an
inhomogeneous magnetic field. We first consider entanglement teleportation, and
then focus on the teleportation fidelity under different conditions. The
effects of anisotropy and the magnetic field, both uniform and inhomogeneous,
are discussed. We also find that, though entanglement teleportation does
require an entangled quantum channel, a nonzero critical value of minimum
entanglement is not always necessary.


title:
Geometric phase of a bipartite system with Dzyaloshinski-Moriya
  interaction

abstract:
  The Berry phase of a bipartite system described by a Heisenberg XXZ model
driven by a one-site magnetic field is investigated. The effect of the
Dzyaloshinski-Moriya (DM) anisotropic interaction on the Berry phase is
discussed. It is found that the DM interaction affects the Berry phase
monotonously, and can also cause sudden change of the Berry phase for some weak
magnetic field cases.


title: Detecting Sound-Wave-Like Surface Brightness Ripples in Cluster Cores

abstract:
  We investigate the observational requirements for the detection of
sound-wave-like features in galaxy cluster cores. We calculate the effect of
projection on the observed wave amplitude, and find that the projection factor
depends only weakly on the underlying cluster properties but strongly on the
wavelength of the sound waves, with the observed amplitude being reduced by a
factor ~5 for 5 kpc waves but only by a factor ~ 2 for 25 kpc waves. We go on
to estimate the time needed to detect ripples similar to those previously
detected in the Perseus cluster in other clusters. We find that the detection
time scales most strongly with the flux of the cluster and the amplitude of the
ripples. By connecting the ripple amplitude to the heating power in the system,
we estimate detection times for a selection of local clusters and find that
several may have ripples detected with ~1Ms Chandra time.


title:
Entangled quantum heat engines based on two two-spin systems with
  Dzyaloshinski-Moriya anisotropic antisymmetric interaction

abstract:
  We construct an entangled quantum heat engine (EQHE) based on two two-spin
systems with Dzyaloshinski-Moriya (DM) anisotropic antisymmetric interaction.
By applying the explanations of heat transferred and work performed at the
quantum level in Kieu's work [PRL, 93, 140403 (2004)], the basic thermodynamic
quantities, i.e., heat transferred, net work done in a cycle and efficiency of
EQHE are investigated in terms of DM interaction and concurrence. The validity
of the second law of thermodynamics is confirmed in the entangled system. It is
found that there is a same efficiency for both antiferromagnetic and
ferromagnetic cases, and the efficiency can be controlled in two manners: 1.
only by spin-spin interaction J and DM interaction D; 2. only by the
temperature T and concurrence C. In order to obtain a positive net work, we
need not entangle all qubits in two two-spin systems and we only require the
entanglement between qubits in a two-spin system not be zero. As the ratio of
entanglement between qubits in two two-spin systems increases, the efficiency
will approach infinitely the classical Carnot one. An interesting phenomenon is
an abrupt transition of the efficiency when the entanglements between qubits in
two two-spin systems are equal.


title: Testing the Majorana Nature of Gluinos and Neutralinos

abstract:
  Gluinos and neutralinos, supersymmetric partners of gluons and neutral
electroweak gauge and Higgs bosons, are Majorana particles in the Minimal
Supersymmetric Standard Model [MSSM]. Decays of such self-conjugate particles
generate charge symmetric ensembles of final states. Moreover, production
channels of supersymmetric particles at colliders are characteristically
affected by the Majorana nature of particles exchanged in the production
processes. The sensitivity to the Majorana character of the particles can be
quantified by comparing the predictions with Dirac exchange mechanisms. A
consistent framework for introducing gluino and neutralino Dirac fields can be
designed by extending the N=1 supersymmetry of the MSSM to N=2 in the gauge
sector. We examine to which extent like-sign dilepton production in the
processes q q -> ~q ~q and e- e- -> ~e- ~e- is affected by the exchange of
either Majorana or Dirac gluinos and neutralinos, respectively, at the Large
Hadron Collider (LHC) and in the prospective e- e- mode of a lepton linear
collider.


title: Tropical R maps and Affine Geometric Crystals

abstract:
  By modifying the method in [KNO], certain affine geometric crystals are
realized in affinization of the fundamental representation $W(\varpi_1)_l$ and
the tropical R maps for the affine geometric crystals are described explicitly.
We also define prehomogeneous geometric crystals and show that for a positive
geometric crystal, the connectedness of the corresponding ultra-discretized
crystal is the sufficient condition for prehomogeneity of the positive
geometric crystal. Moreover, the uniqueness of tropical R maps is discussed.


title:
Relationship between vibrations and dynamical heterogeneity in a model
  glass former: extended soft modes but local relaxation

abstract:
  We study the relation between short-time vibrational modes and long-time
relaxational dynamics in a kinetically constrained lattice gas with harmonic
interactions between neighbouring particles. We find a correlation between the
location of the low (high) frequency vibrational modes and regions of high
(low) propensity for motion. This is similar to what was observed in continuous
force systems, but our interpretation is different: in our case relaxation is
due to localised excitations which propagate through the system; these
localised excitations act as background disorder for the elastic network,
giving rise to anomalous vibrational modes. Our results show that a correlation
between spatially extended low frequency modes and high propensity regions does
not imply that relaxational dynamics originates in extended soft modes. We
consider other measures of elastic heterogeneity, such as non-affine
displacement fields and mode localisation lengths, and discuss implications of
our results to interpretations of dynamic heterogeneity more generally.


title: Imaging of granular sources in high energy heavy ion collisions

abstract:
  We investigate the source imaging for a granular pion-emitting source model
in high energy heavy ion collisions. The two-pion source functions of the
granular sources exhibit a two-tiered structure. Using a parametrized formula
of granular two-pion source function, we examine the two-tiered structure of
the source functions for the imaging data of Au+Au collisions at Alternating
Gradient Synchrotron (AGS) and Relativistic Heavy Ion Collider (RHIC). We find
that the imaging technique introduced by Brown and Danielewicz is suitable for
probing the granular structure of the sources. Our data-fitting results
indicate that there is not visible granularity for the sources at AGS energies.
However, the data for the RHIC collisions with the selections of $40 < {\rm
centrality} < 90%$ and $0.20<k_{\rm T}<0.36$ GeV/c are better described by the
model with granular emission than that of one Gaussian. The model with granular
source has more parameters than the simple Gaussian, hence can describe more
complicated shapes.


title: Properties of X-ray selected Broad Absorption Line Quasars

abstract:
  Broad absorption line quasars (commonly termed BALQSOs) contain the most
dramatic examples of AGN-driven winds. The high absorbing columns in these
winds, ~10^24 cm^-2, ensure that BALQSOs are generally X-ray faint. This high
X-ray absorption means that almost all BALQSOs have been discovered through
optical surveys, and so what little we know about their X-ray properties is
derived from very bright optically-selected sources. A small number of X-ray
selected BALQSOs (XBALQSOs) have, however, recently been found in deep X-ray
survey fields. In this paper we investigate the X-ray and rest-frame UV
properties of five XBALQSOs for which we have obtained XMM-Newton EPIC X-ray
spectra and deep optical imaging and spectroscopy. We find that, although the
XBALQSOs have an alpha_ox steeper by ~0.5 than normal QSOs, their median
alpha_ox is nevertheless flatter by 0.30 than that of a comparable sample of
optically selected BALQSOs (OBALQSOs). We rule out the possibility that the
higher X-ray to optical flux ratio is due to intrinsic optical extinction. We
find that the amount of X-ray and UV absorption due to the wind in XBALQSOs is
similar, or perhaps greater than, the corresponding wind absorption in
OBALQSOs, so the flatter alpha_ox cannot be a result of weaker wind absorption.
We conclude that these XBALQSOs have intrinsically higher X-ray to optical flux
ratios than the OBALQSO sample with which we compare them.


title: Decision Theory is a Red Herring for the Many Worlds Interpretation

abstract:
  There have been many attempts over the years to derive the Born Rule from the
wave equation since Everett's Many Worlds Interpretation was proposed; however,
none of these have been satisfactory as shown when critics pointed out
loopholes and unsupported assumptions. In this paper the case is made that the
currently fashionable decision-theoretic approach founded by David Deutsch and
explicated by David Wallace is likewise unsatisfactory. A more fundamental
computationalist approach is advocated.


title: Highly-flexible wide angle of incidence terahertz metamaterial absorber

abstract:
  We present the design, fabrication, and characterization of a metamaterial
absorber which is resonant at terahertz frequencies. We experimentally
demonstrate an absorptivity of 0.97 at 1.6 terahertz. Importantly, this
free-standing absorber is only 16 microns thick resulting in a highly flexible
material that, further, operates over a wide range of angles of incidence for
both transverse electric and transverse magnetic radiation.


title: On NFAs Where All States are Final, Initial, or Both

abstract:
  We examine questions involving nondeterministic finite automata where all
states are final, initial, or both initial and final. First, we prove hardness
results for the nonuniversality and inequivalence problems for these NFAs.
Next, we characterize the languages accepted. Finally, we discuss some state
complexity problems involving such automata.


title:
Superstring and Superstring Field Theory: a new solution using
  Ultradistributions of Exponential Type

abstract:
  In this paper we show that Ultradistributions of Exponential Type (UET) are
appropriate for the description in a consistent way superstring and superstring
field theories. A new Lagrangian for the closed superstring is given. We show
that the superstring field is a linear superposition of UET of compact support,
and give the notion of anti-superstring. We evaluate the propagator for the
superstring field, and calculate the convolution of two of them.


title: Embedding operators into strongly continuous semigroups

abstract:
  We study linear operators $T$ on Banach spaces for which there exists a
$C_0$-semigroup $(T(t))_{t\geq 0}$ such that $T=T(1)$. We present a necessary
condition in terms of the spectral value 0 and give classes of examples where
this can or cannot be achieved.


title: A local scheme accounting for EPR quantum correlations

abstract:
  A model for two entangled systems in an EPR setting is shown to reproduce the
quantum-mechanical outcomes and expectation values. Each system is represented
by a small sphere containing a point-like particle embedded in a field. A
quantum state appears as an equivalence class of several possible
particle-field configurations. Contrarily to Bell-type hidden variables models,
the fields account for the non-commutative aspects of the measurements and deny
the simultaneous reality of incompatible physical quantities, thereby allowing
to escape EPR's "completeness or locality" dilemma.


title:
Dynamics of driven vortex-antivortex matter in superconducting films
  with a magnetic dipole array

abstract:
  We investigate theoretically vortex-antivortex (v-av) matter moving in thin
superconducting films with a regular array of in-plane magnetic dipoles. Our
model considers v-av pair creation induced by the local current density
generated by the magnetic texture and the transport current and simulates the
dynamics of vortices and antivortices by numerical integration of the Langevin
equation of motion. Calculations of the transport properties at zero applied
field show a strong dependence of the v-av dynamics on the current intensity
and direction. The dynamics of the v-av matter is characterized by a series of
creation and annihilation processes, which reflect on the time dependence of
the electrical field, and by guided motion, resulting in a zero-field
transverse resistance.


title:
A study of the electromagnetic fluctuation induced forces on thin
  metallic films

abstract:
  Using the plasma model for the metal dielectric function we have calculated
the electromagnetic fluctuation induced forces on a free standing metallic film
in vacuum as a function of the film size and the plasma frequency. The force
for unit area is attractive and for a given film thickness it shows an
intensity maximum at a specific plasma value, which cannot be predicted on the
basis of a non retarded description of the electromagnetic interaction. If the
film is deposited on a substrate or interacts with a plate, both the sign and
the value of the force are modified. It is shown that the force can change sign
from attraction to repulsion upon changing the substrate plasma frequency. A
detailed comparison between the force on the film boundaries and the force
between film and substrate indicates that, for 50-100 nm thick films, they are
comparable when film-substrate distance is of the order of the film thickness.


title: Graphs, Frobenius functionals, and the classical Yang-Baxter equation

abstract:
  A Lie algebra is Frobenius if it admits a linear functional F such that the
Kirillov form F([x,y]) is non-degenerate. If g is the m-th maximal parabolic
subalgebra P(n,m) of sl(n) this occurs precisely when (n,m) = 1. We define a
"cyclic" functional F on P(n,m) and prove it is non-degenerate using properties
of certain graphs associated to F. These graphs also provide in some cases
readily computable associated solutions of the classical Yang-Baxter equation.
We also define a local ring associated to each connected loopless graph from
which we show that the graph can be reconstructed. Finally, we examine the
seaweed Lie algebras of Dergachev and Kirillov from our perspective.


title: The age incidence of any cancer can be explained by a one-mutation model

abstract:
  We propose a one mutation model for cancer with a mutation rate that
increases with time. Under rather general hypotheses the number of mutations is
necessarily a (non homogeneous) Poisson process with the prescribed mutation
rate. We show that the cumulative probability of cancer up to time $t$ is, up
to a multiplicative constant, an antiderivative of the mutation rate.


title:
Solving the $\eta$-Problem in Hybrid Inflation with Heisenberg Symmetry
  and Stabilized Modulus

abstract:
  We propose a class of models in which the $\eta$-problem of supersymmetric
hybrid inflation is resolved using a Heisenberg symmetry, where the associated
modulus field is stabilized and made heavy with the help of the large vacuum
energy during inflation without any fine-tuning. The proposed class of models
is well motivated both from string theory considerations, since it includes the
commonly encountered case of no-scale supergravity Kaehler potential, and from
the perspective of particle physics since a natural candidate for the inflaton
in this class of models is the right-handed sneutrino which is massless during
the inflationary epoch, and subsequently acquires a large mass at the end of
inflation. We study a specific example motivated by sneutrino hybrid inflation
with no-scale supergravity in some detail, and show that the spectral index may
lie within the latest WMAP range, while the tensor-to-scalar ratio is very
small.


title: Experiments on propagating and branching positive streamers in air

abstract:
  This proceedings paper from 2004 contains figures of discharges in different
gap lengths at the same potential that are not available elsewhere. The 2004
abstract: The evolution of streamers is known to depend on gas composition and
electrode geometry, on polarity and size of the voltage and also on the
electric circuit that produces the high voltage pulse. To characterize the
phenomena better and to compare with theory, a new larger experimental setup
with vacuum enclosure has been built. We here present first results in this
setup on positive streamers in air at fixed voltage and varying electrode
distance. While next to the emitting anode tip, a similar number of streamers
seems to emerge due to multiple branching, more streamers seem to survive over
a fixed distance, when the gap is shorter. When lowering the voltage, streamers
branch less at all distances from the anode tip or do not branch at all beyond
a certain distance.


title:
On the genuine bound states of a non-relativistic particle in a linear
  finite range potential

abstract:
  We explore the energy spectrum of a non-relativistic particle bound in a
linear finite range, attractive potential, envisaged as a quark-confining
potential. The intricate transcendental eigenvalue equation is solved
numerically to obtain the explicit eigen-energies. The linear potential, which
resembles the triangular well, has potential significance in particle physics
and exciting applications in electronics.


title:
Author-choice open access publishing in the biological and medical
  literature: a citation analysis

abstract:
  In this article, we analyze the citations to articles published in 11
biological and medical journals from 2003 to 2007 that employ author-choice
open access models. Controlling for known explanatory predictors of citations,
only 2 of the 11 journals show positive and significant open access effects.
Analyzing all journals together, we report a small but significant increase in
article citations of 17%. In addition, there is strong evidence to suggest that
the open access advantage is declining by about 7% per year, from 32% in 2004
to 11% in 2007.


title: Role of vacuum fluctuation forces in thin metal film stability

abstract:
  Thin metal films are subject to the pressure caused by the zero point
oscillations of the electromagnetic field, which depends upon the film optical
properties and, in case of deposition onto a substrate, upon the substrate
reflectivity. It has been suggested that this force may be relevant in
determining the stability of deposited pseudomorphic films with respect to
buckling or island formation. We present a detailed analysis of its behaviour
as a function of the optical parameters and of the film thickness and we
illustrate the conditions under which it may play some role. For free standing
films it turns out that the film stabilization is basically due to the surface
stress, which largely overwhelms the vacuum force. For epilayers on metal
substrate the vacuum force may be important, and we give stability diagrams and
critical thicknesses for several cases, illustrating how the flat surface
growth may depend upon the film parameters. The importance of including
retardation effects into the theory for a realistic determination of the
stability conditions is also discussed.


title:
Hopping conduction in strong electric fields: Negative differential
  conductivity

abstract:
  Effects of strong electric fields on hopping conductivity are studied
theoretically. Monte-Carlo computer simulations show that the analytical theory
of Nguyen and Shklovskii [Solid State Commun. 38, 99 (1981)] provides an
accurate description of hopping transport in the limit of very high electric
fields and low concentrations of charge carriers as compared to the
concentration of localization sites and also at the relative concentration of
carriers equal to 0.5. At intermediate concentrations of carriers between 0.1
and 0.5 computer simulations evidence essential deviations from the results of
the existing analytical theories.
  The theory of Nguyen and Shklovskii also predicts a negative differential
hopping conductivity at high electric fields. Our numerical calculations
confirm this prediction qualitatively. However the field dependence of the
drift velocity of charge carriers obtained numerically differs essentially from
the one predicted so far. Analytical theory is further developed so that its
agreement with numerical results is essentially improved.


title: A Simple E-Voting Protocol

abstract:
  We propose an e-voting protocol that seems to allow citizens to verify that
their vote has been accurately taken into account while preserving its secrecy,
without requiring the use of a complex process. The main idea is to give each
voter a receipt on which her choice is mixed with the choices of other voters.


title:
The construction of non-spherical models of quasi-relaxed stellar
  systems

abstract:
  Spherical models of collisionless but quasi-relaxed stellar systems have long
been studied as a natural framework for the description of globular clusters.
Here we consider the construction of self-consistent models under the same
physical conditions, but including explicitly the ingredients that lead to
departures from spherical symmetry. In particular, we focus on the effects of
the tidal field associated with the hosting galaxy. We then take a stellar
system on a circular orbit inside a galaxy represented as a "frozen" external
field. The equilibrium distribution function is obtained from the one
describing the spherical case by replacing the energy integral with the
relevant Jacobi integral in the presence of the external tidal field. Then the
construction of the model requires the investigation of a singular perturbation
problem for an elliptic partial differential equation with a free boundary, for
which we provide a method of solution to any desired order, with explicit
solutions to two orders. We outline the relevant parameter space, thus opening
the way to a systematic study of the properties of a two-parameter family of
physically justified non-spherical models of quasi-relaxed stellar systems. The
general method developed here can also be used to construct models for which
the non-spherical shape is due to internal rotation. Eventually, the models
will be a useful tool to investigate whether the shapes of globular clusters
are primarily determined by internal rotation, by external tides, or by
pressure anisotropy.


title:
Maximal regularity for parabolic partial differential equations on
  manifolds with cylindrical ends

abstract:
  We give a short, simple proof of maximal regularity for linear parabolic
evolution equations on manifolds with cylindrical ends by making use of
pseudodifferential parametrices and the concept of R-boundedness for the
resolvent.


title: Deformations of the Tracy-Widom distribution

abstract:
  In random matrix theory (RMT), the Tracy-Widom (TW) distribution describes
the behavior of the largest eigenvalue. We consider here two models in which TW
undergoes transformations. In the first one disorder is introduced in the
Gaussian ensembles by superimposing an external source of randomness. A
competition between TW and a normal (Gaussian) distribution results, depending
on the spreading of the disorder. The second model consists in removing at
random a fraction of (correlated) eigenvalues of a random matrix. The usual
formalism of Fredholm determinants extends naturally. A continuous transition
from TW to the Weilbull distribution, characteristc of extreme values of an
uncorrelated sequence, is obtained.


title:
A Study of H2 Emission in Three Bipolar Proto-Planetary Nebulae: IRAS
  16594-4656, Hen 3-401, and Rob 22

abstract:
  We have carried out a spatial-kinematical study of three proto-planetary
nebulae, IRAS 16594-4656, Hen 3-401, and Rob 22. High-resolution H2 images were
obtained with NICMOS on the HST and high-resolution spectra were obtained with
the Phoenix spectrograph on Gemini-South. IRAS 16594-4656 shows a
"peanut-shaped" bipolar structure with H2 emission from the walls and from two
pairs of more distant, point-symmetric faint blobs. The velocity structure
shows the polar axis to be in the plane of the sky, contrary to the impression
given by the more complex visual image and the visibility of the central star,
with an ellipsoidal velocity structure. Hen 3-401 shows the H2 emission coming
from the walls of the very elongated, open-ended lobes seen in visible light,
along with a possible small disk around the star. The bipolar lobes appear to
be tilted 10-15 deg with respect to the plane of the sky and their kinematics
display a Hubble-like flow. In Rob 22, the H2 appears in the form of an "S"
shape, approximately tracing out the similar pattern seen in the visible. H2 is
especially seen at the ends of the lobes and at two opposite regions close to
the unseen central star. The axis of the lobes is nearly in the plane of the
sky. Expansion ages of the lobes are calculated to be approximately 1600 yr
(IRAS 16594-4656), 1100 yr (Hen 3-401), and 640 yr (Rob 22), based upon
approximate distances.


title: Resolving temporal Gribov copies in Coulomb gauge Yang-Mills theory

abstract:
  The continuum Yang-Mills functional integral within the first order formalism
and in Coulomb gauge is studied. In particular, the temporal zero-modes of the
Faddeev-Popov operator are explicitly accounted for. It is shown that the
treatment of these zero-modes results in the constraint that the total color
charge of the system vanishes at all times. Further, it is argued that the
functional integral is effectively fully gauge-fixed once Gauss' law has been
resolved in Coulomb gauge.


title:
A Markov Chain Monte Carlo for Galactic Cosmic Ray physics: I. Method
  and results for the Leaky Box Model

abstract:
  Propagation of charged cosmic-rays in the Galaxy depends on the transport
parameters, whose number can be large depending on the propagation model under
scrutiny. A standard approach for determining these parameters is a manual
scan, leading to an inefficient and incomplete coverage of the parameter space.
We implement a Markov Chain Monte Carlo (MCMC), which is well suited to
multi-parameter determination. Its specificities (burn-in length, acceptance,
and correlation length) are discussed in the phenomenologically well-understood
Leaky-Box Model. From a technical point of view, a trial function based on
binary-space partitioning is found to be extremely efficient, allowing a
simultaneous determination of up to nine parameters, including transport and
source parameters, such as slope and abundances. Our best-fit model includes
both a low energy cut-off and reacceleration, whose values are consistent with
those found in diffusion models. A Kolmogorov spectrum for the diffusion slope
(delta=1/3) is excluded. The marginalised probability-density function for
delta and alpha (the slope of the source spectra) are delta~0.55-0.60 and
alpha~2.14-2.17, depending on the dataset used and the number of free
parameters in the fit. All source-spectrum parameters (slope and abundances)
are positively correlated among themselves and with the reacceleration
strength, but are negatively correlated with the other propagation parameters.
A forthcoming study will extend our analysis to more physical diffusion models.


title: Vacuum fluctuation forces between ultra-thin films

abstract:
  We have investigated the role of the quantum size effects in the evaluation
of the force caused by electromagnetic vacuum fluctuations between ultra-thin
films, using the dielectric tensor derived from the particle in a box model.
Comparison with the results obtained by adopting a continuum dielectric model
shows that, for film thicknesses of 1-10 nm, the electron confinement causes
changes in the force intensity with respect to the isotropic plasma model which
range from 40% to few percent depending upon the film electron density and the
film separation. The calculated force shows quantum size oscillations, which
can be significant for film separation distances of several nanometers. The
role of electron confinement in reducing the large distance Casimir force is
discussed.


title: Simple Cohen-Macaulay Codimension 2 Singularities

abstract:
  In this article, we provide a complete list of simple Cohen-Macaulay
codimension 2 singularities together with a list of adjacencies which is
complete in the case of fat point and space curve singularities.


title: Rigidity and uniruling for Lagrangian submanifolds

abstract:
  This paper explores the topology of monotone Lagrangian submanifolds $L$
inside a symplectic manifold $M$ by exploiting the relationships between the
quantum homology of $M$ and various quantum structures associated to the
Lagrangian $L$.


title: Extremely red stellar objects revealed by IPHAS

abstract:
  We present photometric analysis and follow-up spectroscopy for a population
of extremely red stellar objects extracted from the point-source catalogue of
the INT Photometric H-Alpha Survey (IPHAS) of the northern galactic plane. The
vast majority of these objects have no previous identification. Analysis of
optical, near- and mid-infrared photometry reveals that they are mostly
highly-reddened asymptotic giant branch stars, with significant levels of
circumstellar material. We show that the distribution of these objects traces
galactic extinction, their highly reddened colours being a product of both
interstellar and circumstellar reddening. This is the first time that such a
large sample of evolved low-mass stars has been detected in the visual and
allows optical counterparts to be associated with sources from recent infrared
surveys.
  Follow-up spectroscopy on some of the most interesting objects in the sample
has found significant numbers of S-type stars which can be clearly separated
from oxygen-rich objects in the IPHAS colour-colour diagram. We show that this
is due to the positions of different molecular bands relative to the
narrow-band H-alpha filter used for IPHAS observations. The IPHAS (r' -
H-alpha) colour offers a valuable diagnostic for identifying S-type stars. A
selection method for identifying S-type stars in the galactic plane is briefly
discussed and we estimate that over a thousand new objects of this type may be
discovered, potentially doubling the number of known objects in this short but
important evolutionary phase.


title: d- and f-orbital correlations in the REFeAsO compounds

abstract:
  We estimate theoretically the strength of the local Coulomb interaction for
the Fe 3d and Ce 4f shells in the REFeAsO compunds. In LaFeAsO and CeFeAsO we
obtain values of the local Coulomb interaction parameter U for both Fe and Ce
which are larger than those of elemental Fe and Ce metals. The Fe 3d bandwidth
of REFeAsO is found to increase slightly as one moves along the RE-series.
Using a combined local density approximation and dynamical mean-field theory
(LDA+DMFT) approach, we study the behaviour of the localized 4f states along
the rare-earth oxyarsenides REFeAsO series (RE=Ce,Pr,Nd). In CeFeAsO the
occupied Ce 4f band is located just below the Fe 3d band leading possibly to a
Kondo screening of the 4f local moment under applied pressure, while the
unscreened local moment behaviour is expected for the Pr and Nd compounds.


title: The Schr\"odinger equation with piercings

abstract:
  We show that the spectrum of the Schr\"odinger equation in two or higher
dimensions does not change when Dirichlet boundary conditions are enforced on a
number of isolated points inside the original domain (piercings). We have
obtained the analytical solution for spherically symmetric state of the
$d$-dimensional simple harmonic oscillator pierced at the origin. Results for
the case with multiple piercings are obtained numerically and agree with the
theoretical prediction. In the case of a two dimensional parabolic quantum dot
with two electrons and a single piercing in the origin we show that the energy
of the ground state calculated to first order in perturbation theory goes over
to the equivalent result in absence of piercing as the radius of the piercing
becomes infinitesimal. Interestingly, we find that the leading finite size
correction to the interaction energy is negative while the corresponding
correction to the single particle energies is (as expected) positive. For a
finite radius of the piercing and above a critical coupling, the first term
dominates the second and the total energy of the dot with piercing is lower.
Unfortunately the critical coupling found for this example is nonperturbative.
Finally we study configurations allowing bound states in the continuum, showing
that bound states survive to the insertion of piercings and that their energy
is unchanged when the radius of the piercing vanishes.


title:
Strong generic vanishing and a higher dimensional Castelnuovo-de
  Franchis inequality

abstract:
  We extend to manifolds of arbitrary dimension the Castelnuovo-de Franchis
inequality for surfaces. The proof is based on the theory of Generic Vanishing
and higher regularity, and on the Evans-Griffith Syzygy Theorem in commutative
algebra. Along the way we give a positive answer, in the setting of K\"ahler
manifolds, to a question of Green-Lazarsfeld on the vanishing of higher direct
images of Poincar\'e bundles. We indicate generalizations to arbitrary
Fourier-Mukai transforms.


title:
Observation of an enhancement in e+e- to Upsilon(1S)pi+pi-,
  Upsilon(2S)pi+pi-, and Upsilon(3S)pi+pi- production near sqrt{s}=10.89 GeV at
  Belle

abstract:
  We measure the production cross sections for e+e- -> Upsilon(1S)pi+pi-,
Upsilon(2S)pi+pi-, and Upsilon(3S)pi+pi- as a function of sqrt{s} between 10.83
GeV and 11.02 GeV. The data consists of 8.1 fb^-1 collected with the Belle
detector at the KEKB e+e- collider. We observe enhanced production in all three
final states that does not agree well with the conventional Upsilon(10860)
lineshape. A fit using a Breit-Wigner resonance shape yields a peak mass of
[10888.4 +2.7/-2.6 (stat) +- 1.2 (syst)] MeV/c^2 and a width of [30.7 +8.3/-7.0
(stat) +- 3.1 (syst)] MeV/c^2.


title:
Search for Supersymmetry in ppbar Collisions at sqrt(s)=1.96 TeV Using
  the Trilepton Signature for Chargino-Neutralino Production

abstract:
  We use the three lepton and missing energy "trilepton" signature to search
for chargino-neutralino production with 2.0 inverse femtobarns of integrated
luminosity collected by the CDF II experiment at the Tevatron ppbar collider.
We expect an excess of approximately 11 supersymmetric events for a choice of
parameters of the mSUGRA model, but our observation of 7 events is consistent
with the standard model expectation of 6.4 events. We constrain the mSUGRA
model of supersymmetry and rule out chargino masses up to 145 GeV/c^2 for a
specific choice of parameters.


title:
Quadratic reciprocity and the sign of the Gauss sum via the finite Weil
  representation

abstract:
  We give new proofs of two basic results in number theory: The law of
quadratic reciprocity and the sign of the Gauss sum. We show that these results
are encoded in the relation between the discrete Fourier transform and the
action of the Weyl element in the Weil representation modulo p,q and pq.


title:
Three-point Green function of massless QED in position space to lowest
  order

abstract:
  The transverse part of the three-point Green function of massless QED is
determined to the lowest order in position space. Taken together with the
evaluation of the longitudinal part in arXiv:0803.2630, this gives a relation
for QED which is analogous to the star-triangle relation. We relate our result
to conformal-invariant three-point functions.


title: Infrared Propagator Corrections for Constant Deceleration

abstract:
  We derive the propagator for a massless, minimally coupled scalar on a
$D$-dimensional, spatially flat, homogeneous and isotropic background with
arbitrary constant deceleration parameter. Our construction uses the operator
formalism, by integrating the Fourier mode sum. We give special attention to
infrared corrections from the nonzero lower limit associated with working on
finite spatial sections. These corrections eliminate infrared divergences that
would otherwise be incorrectly treated by dimensional regularization, resulting
in off-coincidence divergences for those special values of the deceleration
parameter at which the infrared divergence is logarithmic. As an application we
compute the expectation value of the scalar stress-energy tensor.


title: An Instanton Toolbox for F-Theory Model Building

abstract:
  Several dimensionful parameters needed for model building can be engineered
in a certain class of SU(5) F-theory GUTs by adding extra singlet fields which
are localized along pairwise intersections of D7-branes. The values of these
parameters, however, depend on dynamics external to the GUT which causes the
singlets to acquire suitable masses or expectation values. In this note, we
demonstrate that D3-instantons which wrap the same 4-cycle as one of the
intersecting D7's can provide precisely the needed dynamics to generate several
important scales, including the supersymmetry-breaking scale and the
right-handed neutrino mass. Furthermore, these instantons seem unable to
directly generate the \mu term suggesting that, at least in this class of
models, it should perhaps be tied to one of the other scales in the problem.
More specifically, we study the simple system consisting of a pair of D7-branes
wrapping del Pezzo surfaces which intersect along a curve $\Sigma$ of genus 0
or 1 and classify all instanton configurations which can potentially contribute
to the superpotential. This allows one to formulate topological conditions
which must be imposed on \Sigma for various model-building applications. Along
the way, we also observe that the construction of arXiv:0808.1286 which
engineers a linear superpotential in fact realizes an O'Raifeartaigh model at
the KK scale whose 1-loop Coleman-Weinberg potential generically leads to a
metastable, long-lived SUSY-breaking vacuum.


title: Bergman Kernel from Path Integral

abstract:
  We rederive the expansion of the Bergman kernel on Kahler manifolds developed
by Tian, Yau, Zelditch, Lu and Catlin, using path integral and perturbation
theory, and generalize it to supersymmetric quantum mechanics. One physics
interpretation of this result is as an expansion of the projector of wave
functions on the lowest Landau level, in the special case that the magnetic
field is proportional to the Kahler form. This is relevant for the quantum Hall
effect in curved space, and for its higher dimensional generalizations. Other
applications include the theory of coherent states, the study of balanced
metrics, noncommutative field theory, and a conjecture on metrics in black hole
backgrounds. We give a short overview of these various topics. From a
conceptual point of view, this expansion is noteworthy as it is a geometric
expansion, somewhat similar to the DeWitt-Seeley-Gilkey et al short time
expansion for the heat kernel, but in this case describing the long time limit,
without depending on supersymmetry.


title:
Observation of Distinct Electron-Phonon Couplings in Gated Bilayer
  Graphene

abstract:
  A Raman study of a back gated bilayer graphene sample is presented. The
changes in the Fermi level induced by charge transfer splits the Raman G-band,
hardening its higher component and softening the lower one. These two
components are associated with the symmetric (S) and anti-symmetric vibration
(AS) of the atoms in the two layers, the later one becoming Raman active due to
inversion symmetry breaking. The phonon hardening and softening are explained
by considering the selective coupling of the S and AS phonons with interband
and intraband electron-hole pairs.


title:
The Knudsen temperature jump and the Navier-Stokes hydrodynamics of
  granular gases driven by thermal walls

abstract:
  Thermal wall is a convenient idealization of a rapidly vibrating plate used
for vibrofluidization of granular materials. The objective of this work is to
incorporate the Knudsen temperature jump at thermal wall in the Navier-Stokes
hydrodynamic modeling of dilute granular gases of monodisperse particles that
collide nearly elastically. The Knudsen temperature jump manifests itself as an
additional term, proportional to the temperature gradient, in the boundary
condition for the temperature. Up to a numerical pre-factor of order unity,
this term is known from kinetic theory of elastic gases. We determine the
previously unknown numerical pre-factor by measuring, in a series of molecular
dynamics (MD) simulations, steady-state temperature profiles of a gas of
elastically colliding hard disks, confined between two thermal walls kept at
different temperatures, and comparing the results with the predictions of a
hydrodynamic calculation employing the modified boundary condition. The
modified boundary condition is then applied, without any adjustable parameters,
to a hydrodynamic calculation of the temperature profile of a gas of inelastic
hard disks driven by a thermal wall. We find the hydrodynamic prediction to be
in very good agreement with MD simulations of the same system. The results of
this work pave the way to a more accurate hydrodynamic modeling of driven
granular gases.


title: (pi,pi)-electronic order in iron arsenide superconductors

abstract:
  The distribution of valence electrons in metals usually follows the symmetry
of an ionic lattice. Modulations of this distribution often occur when those
electrons are not stable with respect to a new electronic order, such as spin
or charge density waves. Electron density waves have been observed in many
families of superconductors[1-3], and are often considered to be essential for
superconductivity to exist[4]. Recent measurements[5-9] seem to show that the
properties of the iron pnictides[10, 11] are in good agreement with band
structure calculations that do not include additional ordering, implying no
relation between density waves and superconductivity in those materials[12-15].
Here we report that the electronic structure of Ba1-xKxFe2As2 is in sharp
disagreement with those band structure calculations[12-15], instead revealing a
reconstruction characterized by a (pi,pi) wave vector. This electronic order
coexists with superconductivity and persists up to room temperature.


title: Low energy spin waves and magnetic interactions in SrFe$_2$As$_2$

abstract:
  We report inelastic neutron scattering studies of magnetic excitations in
antiferromagnetically ordered SrFe$_{2}$As$_{2}$ ($T_{N}=220$ K), the parent
compound of the FeAs-based superconductors. At low temperatures (T=7 K), the
spectrum of magnetic excitations $S(Q,\hbar \omega)$ consists of a Bragg peak
at the elastic position ($\hbar \omega =0$ meV), a spin gap ($ \Delta \leq 6.5$
meV), and sharp spin wave excitations at higher energies. Based on the observed
dispersion relation, we estimate the effective magnetic exchange coupling using
a Heisenberg model. On warming across $T_{N} $, the low temperature spin gap
rapidly closes, with weak critical scattering and spin-spin correlations in the
paramagnetic state. The antiferromagnetic order in SrFe$_{2}$As$_{2}$ is
therefore consistent with a first order phase transition, similar to the
structural lattice distortion.


title: Experimentally testable state-independent quantum contextuality

abstract:
  We show that there are Bell-type inequalities for noncontextual theories that
are violated by any quantum state. One of these inequalities between the
correlations of compatible measurements is particularly suitable for testing
this state-independent violation in an experiment.


title: Multivariable operator-valued Nevanlinna-Pick interpolation: a survey

abstract:
  The theory of Nevanlinna-Pick and Carath\'eodory-Fej\'er interpolation for
matrix- and operator-valued Schur class functions on the unit disk is now well
established. Recent work has produced extensions of the theory to a variety of
multivariable settings, including the ball and the polydisk (both commutative
and noncommutative versions), as well as a time-varying analogue. Largely
independent of this is the recent Nevanlinna-Pick interpolation theorem by P.S.
Muhly and B. Solel for an abstract Hardy algebra set in the context of a Fock
space built from a $W^*$-correspondence E over a $W^{*}$-algebra $\cA$ and a
*-representation $\sigma$ of $\cA$. In this review we provide an exposition of
the Muhly-Solel interpolation theory accessible to operator theorists, and
explain more fully the connections with the already existing interpolation
literature. The abstract point evaluation first introduced by Muhly-Solel leads
to a tensor-product type functional calculus in the main examples. A second
kind of point-evaluation for the $W^*$-correspondence Hardy algebra, also
introduced by Muhly and Solel, is here further investigated, and a
Nevanlinna-Pick theorem in this setting is proved. It turns out that, when
specified for examples, this alternative point-evaluation leads to an
operator-argument functional calculus and corresponding Nevanlinna-Pick
interpolation. We also discuss briefly several Nevanlinna-Pick interpolation
results for Schur classes that do not fit into the Muhly-Solel
$W^*$-correspondence formalism.


title:
QCD at complex coupling, large order in perturbation theory and the
  gluon condensate

abstract:
  We discuss the relationship between the large order behavior of the
perturbative series for the average plaquette in pure gauge theory and
singularities in the complex coupling plane. We discuss simple extrapolations
of the large order for this series. We point out that when these extrapolated
series are subtracted from the Monte Carlo data, one obtains (naive) estimates
of the gluon condensate that are significantly larger than values commonly used
in the continuum for phenomelogical purpose. We present numerical results
concerning the zeros of the partition function in the complex coupling plane
(Fisher's zeros). We report recent attempts to solve this problem using the
density of states. We show that weak and strong coupling expansions for the
density of states agree surprisingly well for values of the action relevant for
the crossover regime.


title: New measurement of the K+ => pi+,nu,nubar branching ratio

abstract:
  Three events for the decay K+ => pi+,nu,nubar have been observed in the pion
momentum region below the K+ => pi+,pi0 peak, 140 < P_pi < 199 MeV/c, with an
estimated background of 0.93+-0.17(stat.)+0.32-0.24(syst.) events. Combining
this observation with previously reported results yields a branching ratio of
B(K+ => pi+,nu,nubar) = (1.73+1.15-1.05)e-10 consistent with the standard model
prediction.


title: Operator-Valued $L_{q}\to L_{p}$ Fourier Multipliers

abstract: This paper is withdrawn due to some gaps in the proof


title: On Exceptional Collections on Grassmannians

abstract:
  The author was informed that the result in the original version had been
obtained earlier by K. Ueda (arXiv:math/0503355 [math.AG]). The paper is
retracted.


title: Thermal relic abundances of long-lived staus

abstract:
  In supersymmetric models with a long-lived stau being the lightest Standard
Model superpartner, the stau abundance during primordial nucleosynthesis is
tightly constrained. Considering the complete set of stau annihilation channels
in the minimal supersymmetric Standard Model (MSSM) with real parameters for
scenarios in which sparticle coannihilations are negligible, we calculate the
decoupling of the lighter stau from the primordial plasma and identify
processes which are capable to deplete the resulting stau abundance
significantly. We find particularly efficient stau annihilation at the
resonance of the heavy CP-even Higgs boson and for a lighter stau with a
sizeable left-right mixing due to enhanced stau-Higgs couplings. Even within
the constrained MSSM, we encounter both effects leading to exceptionally small
values of the resulting stau abundance. Prospects for collider phenomenology
are discussed and possible implications of our findings are addressed with
emphasis on gravitino dark matter scenarios.


title: SO(3) quantum invariants are dense

abstract:
  We show that when $r \geq 5$ is prime, the SO(3) Witten-Reshetikhin-Turaev
quantum invariants for three-manifolds at the level $r$ form a dense set in the
complex plane. This confirms a conjecture of Larsen and Wang.


title: The New DAMA Dark-Matter Window and Energetic-Neutrino Searches

abstract:
  Recently, the DAMA/LIBRA collaboration has repeated and reinforced their
claim to have detected an annual modulation in their signal rate, and have
interpreted this observation as evidence for dark-matter particles at the 8.2
sigma confidence level. Furthermore, it has also been noted that the effects of
channeling may enable a WIMP that scatters elastically via spin-independent
interactions from nuclei to produce the signal observed by DAMA/LIBRA without
exceeding the limits placed by CDMS, XENON, CRESST, CoGeNT and other
direct-detection experiments. To accommodate this signal, however, the mass of
the responsible dark-matter particle must be relatively light, m_{DM} \lsim 10
GeV. Such dark-matter particles will become captured by and annihilate in the
Sun at very high rates, leading to a potentially large flux of GeV-scale
neutrinos. We calculate the neutrino spectrum resulting from WIMP annihilations
in the Sun and show that existing limits from Super-Kamiokande can be used to
close a significant portion of the DAMA region, especially if the dark-matter
particles produce tau leptons or neutrinos in a sizable fraction of their
annihilations. We also determine the spin-dependent WIMP-nuclei
elastic-scattering parameter space consistent with DAMA. The constraints from
Super-Kamiokande on the spin-dependent scenario are even more severe--they
exclude any self-annihilating WIMP in the DAMA region that annihilates 1% of
the time or more to any combination of neutrinos, tau leptons, or charm or
bottom quarks.


title:
Spitzer Observations of the z=2.73 Lensed Lyman Break Galaxy,
  MS1512-cB58

abstract:
  We present Spitzer infrared (IR) photometry and spectroscopy of the lensed
Lyman break galaxy (LBG), MS1512-cB58 at z=2.73. The large (factor ~30)
magnification allows for the most detailed infrared study of an L*_UV(z=3) LBG
to date. Broadband photometry with IRAC (3-10 micron), IRS (16 micron), and
MIPS (24, 70 & 160 micron) was obtained as well as IRS spectroscopy spanning
5.5-35 microns. A fit of stellar population models to the optical/near-IR/IRAC
photometry gives a young age (~9 Myr), forming stars at ~98 M_sun/yr, with a
total stellar mass of ~10^9 M_sun formed thus far. The existence of an old
stellar population with twice the stellar mass can not be ruled out. IR
spectral energy distribution fits to the 24 and 70 micron photometry, as well
as previously obtained submm/mm, data give an intrinsic IR luminosity L_IR =
1-2 x10^11 L_sun and a star formation rate, SFR ~20-40 M_sun/yr. The UV derived
star formation rate (SFR) is ~3-5 times higher than the SFR determined using
L_IR or L_Halpha because the red UV spectral slope is significantly over
predicting the level of dust extinction. This suggests that the assumed
Calzetti starburst obscuration law may not be valid for young LBGs. We detect
strong line emission from Polycyclic Aromatic Hydrocarbons (PAHs) at 6.2, 7.7,
and 8.6 microns. The line ratios are consistent with ratios observed in both
local and high redshift starbursts. Both the PAH and rest-frame 8 micron
luminosities predict the total L_IR based on previously measured relations in
starbursts. Finally, we do not detect the 3.3 micron PAH feature. This is
marginally inconsistent with some PAH emission models, but still consistent
with PAH ratios measured in many local star-forming galaxies.


title: Discovery of VHE gamma-rays from RGB J0152+017

abstract:
  The BL Lac object RGB J0152+017 (z = 0.080) was predicted to be a very
high-energy (VHE; > 100 GeV) gamma-ray source, due to its high X-ray and radio
fluxes.
  We report recent observations of this source made in late October and
November 2007 with the H.E.S.S. array consisting of four imaging atmospheric
Cerenkov telescopes. Contemporaneous observations were made in X-rays with the
Swift and RXTE satellites, in the optical band with the ATOM telescope, and in
the radio band with the Nancay Radio Telescope.
  As a result, RGB J0152+017 is discovered as a source of VHE gamma-rays by
H.E.S.S. A signal of 173 gamma-ray photons corresponding to a statistical
significance of 6.6 sigmas was found in the data. The energy spectrum of the
source can be described by a powerlaw with a spectral index of = 2.95 +-
0.36stat +- 0.20syst. The integral flux above 300 GeV corresponds to ~2% of the
flux of the Crab nebula. The source spectral energy distribution (SED) can be
described using a two-component (extended jet and blob in jet) non-thermal
synchrotron self-Compton (SSC) leptonic model, plus a thermal host galaxy
component. The parameters that are found are very close to those found for TeV
blazars in similar SSC studies.
  The location of its synchrotron peak, as derived from the SED in Swift data,
allows clear classification as a high-frequency-peaked BL Lac (HBL).


title: Energy conditions bounds and supernovae data

abstract:
  The energy conditions play an important role in the description of some
important properties of the Universe, including the current accelerating
expansion phase and the possible recent phase of super-acceleration. In a
recent work we have provided a detailed study of the energy conditions for the
recent past by deriving bounds from energy conditions and by making the
confrontation of the bounds with supernovae data. Here, we extend and update
these results in two different ways. First, by carrying out a new statistical
analysis for $q(z)$ estimates needed for the confrontation between the bounds
and supernovae data. Second, by providing a new picture of the energy
conditions fulfillment and violation in the light of the recently compiled
Union set of 307 type Ia supernovae and by using two different statistical
approaches.


title: Distinguishing seesaw models at LHC with multi-lepton signals

abstract:
  We investigate the LHC discovery potential for electroweak scale heavy
neutrino singlets (seesaw I), scalar triplets (seesaw II) and fermion triplets
(seesaw III). For seesaw I we consider a heavy Majorana neutrino coupling to
the electron or muon. For seesaw II we concentrate on the likely scenario where
the new scalars decay to two leptons. For seesaw III we restrict ourselves to
heavy Majorana fermion triplets decaying to light leptons plus gauge or Higgs
bosons, which are dominant except for unnaturally small mixings. The possible
signals are classified in terms of the charged lepton multiplicity, studying
nine different final states ranging from one to six charged leptons. Using a
fast detector simulation of signals and backgrounds, it is found that the
trilepton channel l+- l+- l-+ is by far the best one for scalar triplet
discovery, and for fermion triplets it is as good as the like-sign dilepton
channel l+- l+-. For heavy neutrinos with a mass O(100) GeV, this trilepton
channel is also better than the usually studied like-sign dilepton mode. In
addition to evaluating the discovery potential, we make special emphasis on the
discrimination among seesaw models if a positive signal is observed. This could
be accomplished not only by searching for signals in different final states,
but also by reconstructing the mass and determining the charge of the new
resonances, which is possible in several cases. For high luminosities, further
evidence is provided by the analysis of the production angular distributions in
the cleanest channels with three or four leptons.


title: MMT Hypervelocity Star Survey

abstract:
  We describe a new survey for unbound hypervelocity stars (HVSs), stars
traveling with such extreme velocities that dynamical ejection from a massive
black hole (MBH) is their most likely origin. We investigate the possible
contribution of unbound runaway stars, and show that the physical properties of
binaries constrain low mass runaways to bound velocities. We measure radial
velocities for HVS candidates with the colors of early A-type and late B-type
stars. We report the discovery of 6 unbound HVSs with velocities and distances
exceeding the conservative escape velocity estimate of Kenyon and
collaborators. We additionally report 4 possibly unbound HVSs with velocities
and distances exceeding the lower escape velocity estimate of Xue and
collaborators. These discoveries increase the number of known HVSs by 60%-100%.
Other survey objects include 19 newly identified z~2.4 quasars. One of the HVSs
may be a horizontal branch star, consistent with the number of evolved HVSs
predicted by Galactic center ejection models. Finding more evolved HVSs will
one day allow a probe of the low-mass regime of HVSs and will constrain the
mass function of stars in the Galactic center.


title:
Measurements of CaII absorption, metals, and dust in a sample of z~1
  DLAs and subDLAs

abstract:
  We present observations of CaII, ZnII, and CrII absorption lines in 16 DLAs
and 6 subDLAs at 0.6 < z < 1.3, obtained for the dual purposes of: (i)
clarifying the relationship between DLAs and absorbers selected via strong CaII
lines, and (ii) increasing the still limited sample of Zn and Cr abundances in
this redshift range. We find only partial overlap between current samples of
intermediate-z DLAs (which are drawn from magnitude limited surveys) and strong
CaII absorbers: approximately 25% of known DLAs at these redshifts have an
associated CaII 3935 line with REW>0.35A, the threshold of the SDSS sample
assembled by Wild and her collaborators. The lack of the strongest systems
(with REW>0.5A) is consistent with these authors' conclusion that such
absorbers are often missed in current DLA surveys because they redden/dim the
light of the background QSOs. We rule out the suggestion that strong CaII
absorption is associated exclusively with the highest-N(HI) DLAs. Furthermore,
we find no correlation between the strength of the CaII lines and either the
metallicity or depletion, although the strongest CaII absorber in our sample is
also the most metal-rich DLA yet discovered, with [Zn/H] ~ solar. We conclude
that a complex mix of parameters determine the strengths of the CaII lines,
including the density of particles and UV photons in the ISM of the galaxies
hosting the DLAs. We find tentative evidence (given the small size of our
sample) that strong CaII systems may preferentially sample regions of high gas
density, perhaps akin to the DLAs exhibiting molecular hydrogen absorption at
redshifts z>2. If this connection is confirmed, strong CaII absorbers would
trace possibly metal-rich, H2-bearing columns of cool, dense gas at distances
up to tens of kpc from normal galaxies. (abridged)


title: Environmental Dependence of Dark Matter Halo Growth I: Halo Merger Rates

abstract:
  In an earlier paper we quantified the mean merger rate of dark matter haloes
as a function of redshift z, descendant halo mass M0, and progenitor halo mass
ratio xi using the Millennium simulation of the LCDM cosmology. Here we broaden
that study and investigate the dependence of the merger rate of haloes on their
surrounding environment. A number of local mass overdensity variables, both
including and excluding the halo mass itself, are tested as measures of a
halo's environment. The simple functional dependence on z, M0, and xi of the
merger rate found in our earlier work is largely preserved in different
environments, but we find that the overall amplitude of the merger rate has a
strong positive correlation with the environmental densities. For galaxy-mass
haloes, we find mergers to occur ~2.5 times more frequently in the densest
regions than in voids at both z=0 and higher redshifts. Higher-mass haloes show
similar trends. We present a fitting form for this environmental dependence
that is a function of both mass and local density and is valid out to z=2. The
amplitude of the progenitor (or conditional) mass function shows a similarly
strong correlation with local overdensity, suggesting that the extended
Press-Schechter model for halo growth needs to be modified to incorporate
environmental effects.


title:
A General Method for Model-Independent Measurements of Particle Spins,
  Couplings and Mixing Angles in Cascade Decays with Missing Energy at Hadron
  Colliders

abstract:
  We outline a general strategy for measuring spins, couplings and mixing
angles in the case of a heavy partner decay chain terminating in an invisible
particle. We consider the common example of a new scalar or fermion D decaying
sequentially to other new particles C, B and A by emitting a quark jet j and
two leptons ln and lf. We derive analytic formulas for the dilepton {ln,lf} and
the two jet-lepton ({j,ln} and {j,lf}) invariant mass distributions for most
general couplings and mixing angles of the new partners. We then consider
various spin assignments for the particles A, B, C and D, and derive the
relevant functional basis for the invariant mass distributions which contains
the intrinsic spin information and does not depend on the couplings and mixing
angles. We propose a new method for determining the spins of the new partners,
using the three experimentally observable distributions {l+,l-}, {j,l+}+{j,l-}
and {j,l+}-{j,l-}. We show that the former two only depend on a single
model-dependent parameter alpha, while the latter may depend on two other
parameters beta and gamma. By fitting these distributions to our set of basis
functions, we are able to do a pure measurement of the spins per se. Our method
is also applicable at a pp-bar collider such as the Tevatron, for which the
previously proposed lepton charge asymmetry is identically zero and does not
contain any spin information. In the process of determining the spins, we also
obtain an independent measurement of the parameters alpha, beta and gamma,
which represent certain combinations of the couplings and the mixing angles of
the heavy partners A, B, C and D.


title: Non-linear theory for multiple M2 branes

abstract:
  We present a manifestly SO(8) invariant non-linear Lagrangian for describing
the non-abelian dynamics of the bosonic degrees of freedom of N coinciding M2
branes in flat spacetime. The theory exhibits a gauge symmetry structure of the
BF type (semidirect product of SU(N) and translations) and at low energies it
reduces exactly to the bosonic part of the Lorentzian Bagger-Lambert Lagrangian
for group SU(N). There are eight scalar fields satisfying a free-scalar
equation. When one of them takes a large expectation value, the non-linear
Lagrangian gets simplified and the theory can be connected to the non-abelian
Lagrangian describing the dynamics of N coinciding D2 branes. As an
application, we show that the BPS fuzzy funnel solution describing M2 branes
ending into a single M5 brane is an exact solution of the non-linear system.


title: Making Almost Commuting Matrices Commute

abstract:
  Suppose two Hermitian matrices $A,B$ almost commute ($\Vert [A,B] \Vert \leq
\delta$). Are they close to a commuting pair of Hermitian matrices, $A',B'$,
with $\Vert A-A' \Vert,\Vert B-B'\Vert \leq \epsilon$? A theorem of H. Lin
shows that this is uniformly true, in that for every $\epsilon>0$ there exists
a $\delta>0$, independent of the size $N$ of the matrices, for which almost
commuting implies being close to a commuting pair. However, this theorem does
not specify how $\delta$ depends on $\epsilon$. We give uniform bounds relating
$\delta$ and $\epsilon$. We provide tighter bounds in the case of block
tridiagonal and tridiagonal matrices and a fully constructive method in that
case. Within the context of quantum measurement, this implies an algorithm to
construct a basis in which we can make a {\it projective} measurement that
approximately measures two approximately commuting operators simultaneously.
Finally, we comment briefly on the case of approximately measuring three or
more approximately commuting operators using POVMs (positive operator-valued
measures) instead of projective measurements.


title: All tree-level amplitudes in N=4 SYM

abstract:
  We give an explicit formula for all tree amplitudes in N=4 SYM, derived by
solving the recently presented supersymmetric tree-level recursion relations.
The result is given in a compact, manifestly supersymmetric form and we show
how to extract from it all possible component amplitudes for an arbitrary
number of external particles and any arrangement of external particles and
helicities. We focus particularly on extracting gluon amplitudes which are
valid for any gauge theory. The formula for all tree-level amplitudes is given
in terms of nested sums of dual superconformal invariants and it therefore
manifestly respects both conventional and dual superconformal symmetry.


title: Algebraic points of small height missing a union of varieties

abstract:
  Let $K$ be a number field, $\overline{\mathbb Q}$, or the field of rational
functions on a smooth projective curve over a perfect field, and let $V$ be a
subspace of $K^N$, $N \geq 2$. Let $Z_K$ be a union of varieties defined over
$K$ such that $V \nsubseteq Z_K$. We prove the existence of a point of small
height in $V \setminus Z_K$, providing an explicit upper bound on the height of
such a point in terms of the height of $V$ and the degree of a hypersurface
containing $Z_K$, where dependence on both is optimal. This generalizes and
improves upon the previous results of the author. As a part of our argument, we
provide a basic extension of the function field version of Siegel's lemma of J.
Thunder to an inequality with inhomogeneous heights. As a corollary of the
method, we derive an explicit lower bound for the number of algebraic integers
of bounded height in a fixed number field.


title: Ionizing Photon Escape Fractions from High Redshift Dwarf Galaxies

abstract:
  It has been argued that low-luminosity dwarf galaxies are the dominant source
of ionizing radiation during cosmological reionization. The fraction of
ionizing radiation that escapes into the intergalactic medium from dwarf
galaxies with masses less than ~10^9.5 solar masses plays a critical role
during this epoch. Using an extensive suite of very high resolution (0.1 pc),
adaptive mesh refinement, radiation hydrodynamical simulations of idealized and
cosmological dwarf galaxies, we characterize the behavior of the escape
fraction in galaxies between 3 x 10^6 and 3 x 10^9 solar masses with different
spin parameters, amounts of turbulence, and baryon mass fractions. For a given
halo mass, escape fractions can vary up to a factor of two, depending on the
initial setup of the idealized halo. In a cosmological setting, we find that
the time-averaged photon escape fraction always exceeds 25% and reaches up to
80% in halos with masses above 10^8 solar masses with a top-heavy IMF. The
instantaneous escape fraction can vary up to an order of magnitude in a few
million years and tend to be positively correlated with star formation rate. We
find that the mean of the star formation efficiency times ionizing photon
escape fraction, averaged over all atomic cooling (T_vir > 8000 K) galaxies,
ranges from 0.02 for a normal IMF to 0.03 for a top-heavy IMF, whereas smaller,
molecular cooling galaxies in minihalos do not make a significant contribution
to reionizing the universe due to a much lower star formation efficiency. These
results provide the physical basis for cosmological reionization by stellar
sources, predominately atomic cooling dwarf galaxies.


title:
On the behavior of bosonic systems in the presence of topology
  fluctuations

abstract:
  The behavior of bosonic systems in the presence of space-time foam is
analyzed within the simplistic model of a set of scalar fields on a flat
background. We discuss the formula for the path integral which allows to
account for the all possible topologies of spacetime. We show that the proper
path integral originates from the parastatistics suggested first by H.S. Green
and that it defines a cutoff for the field theory.


title: Relaxed commutant lifting: existence of a unique solution

abstract:
  In this paper we present necessary and sufficient conditions for the
existence of a unique solution to the relaxed commutant lifting problem. The
obtained conditions are more complicated than those for the classical commutant
lifting setting, and earlier obtained sufficient conditions turn out not to be
necessary conditions. It is also shown that these conditions simplify in
certain special cases.


title:
Chemical Analysis of Five Red Giants in the Globular Cluster M10 (NGC
  6254)

abstract:
  We have determined Al, $\alpha$, Fe-peak, and neutron capture elemental
abundances for five red giant branch (RGB) stars in the Galactic globular
cluster M10. Abundances were determined using equivalent width analyses of
moderate resolution (R$\sim$15,000) spectra obtained with the Hydra multifiber
positioner and bench spectrograph on the WIYN telescope. The data sample the
upper RGB from the luminosity level near the horizontal branch to about 0.5 mag
below the RGB tip. We find in agreement with previous studies that M10 is
moderately metal-poor with [Fe/H]=-1.45 ($\sigma$=0.04). All stars appear
enhanced in Al with $<$[Al/Fe]$>$=+0.33 ($\sigma$=0.19), but no stars have
[Al/Fe]$\ga$+0.55. We find the $\alpha$ elements to be enhanced by +0.20 to
+0.40 dex and the Fe--peak elements to have [el/Fe]$\sim$0, which are
consistent with predictions from type II SN ejecta. Additionally, the cluster
appears to be r-process rich with $<$[Eu/La]$>$=+0.41.


title: AdS Wormholes

abstract:
  We obtain a large class of smooth Lorentzian p-brane wormholes in
supergravities in various dimensions. They connect two asymptotically flat
spacetimes. In cases where there is no dilaton involved in the solution, the
wormhole can connect an AdS_n\times S^m in one asymptotic region to a flat
spacetime in the other. We obtain explicit examples for (n,m)=(4,7), (7,4),
(5,5), (3,3), (3,2). These geometries correspond to field theories with UV
conformal fixed points, and they undergo decompactification in the IR region.
In the case of AdS_3, we compute the central charge of the corresponding
conformal field theory.


title: Inequalities for analytic functions with the derivative in H1

abstract:
  It is proved an inequality - integrated analogue of the Hardy inequality and
as application simplified proof of the theorem of S. A. Vinogradov for the
bounded Toeplitz operators on the space of functions analytic and bounded in
the unit disc is given.


title: Correlated Variability in Blazars

abstract:
  Blazars are thought to emit highly-collimated outflows, so-called jets. By
their close alignment to our line of sight, relativistic beaming effects enable
us to observe these jets over the whole electromagnetic spectrum up to TeV
energies, making them ideal laboratories for studying jet physics. In the last
years multiwavelength observations of blazars provided us with detailed data
sets which helped to characterize the two main components of the
non-relativistic emission, peaking in the optical to X-ray and GeV/TeV energy
region, respectively. In leptonic acceleration models, they are explained by
synchrotron radiation of electrons and inverse-Compton emission from the same
electron population and thus, correlations of both emission regimes are
expected. We review recent observational results on the presence and absence of
such correlations in blazars, and discuss constraints on emission models by
quantitative correlation analyses.


title: Non-Hermitian delocalization and the extinction transition

abstract:
  Logistic growth on a static heterogenous substrate is studied both above and
below the drift-induced delocalization transition. Using stochastic,
agent-based simulations the delocalization of the highest eigenfunction is
connected with the large $N$ limit of the stochastic theory, as the
localization length of the deterministic theory controls the divergence of the
spatial correlation length at the transition. Any finite colony made of
discrete agents is washed away from a heterogeneity with compact support in the
presence of strong wind, thus the transition belongs to the directed
percolation universality class. Some of the difficulties in the analysis of the
extinction transition in the presence of a localized active state are
discussed.