 a sample of B 0 → D − (→ K + π − π − )π + simulated decays, while all other parameters are left free. The small background contribution is described by an exponential function. The measured yield of the B 0 → D − π + mode is N norm = 22 588 ± 176 where the uncertainty is statistical only.
The B 0 (s) → τ ± µ ∓ branching fractions can be written as where N sig (s) is the number of observed B 0 (s) → τ ± µ ∓ decays and α norm (s) a normalisation factor. The latter is defined by Same-sign data Opposite-sign data simulation Figure 2: Final BDT output binned distributions for data and simulated signal samples. The markers are displaced horizontally to improve visibility. 0.14) × 10 −4 [32] and B (τ − → π − π + π − ν τ ) = (9.02 ± 0.05)% [32]. The measured values of α norm where the three quoted uncertainties are the statistical uncertainty due to the sizes of the signal and normalisation simulated and data samples, the systematic uncertainty on the selection efficiencies (dominated by the trigger efficiency contribution, ∼11%) and the total uncertainty on the externally measured quantities. A final BDT is built to split the selected candidates into four samples with different signal-to-background ratios. It combines 16 discriminating variables, none of which are correlated with the B-meson invariant mass. The most important ones are the invariant masses of the three-pion system and of the two combinations of oppositely charged pions, the B-meson IP and flight distance significances, and the output of the BDT based on isolation variables. The output of the BDT is transformed to have a uniform distribution between 0 and 1 for B 0 s → τ ± (→ π ± π ∓ π ± ν τ )µ ∓ simulated decays. As a consequence, its distribution for the background peaks at low BDT values. All samples are divided into four bins of equal width in BDT output. Their distributions are shown in Fig. 2.
The signal yield is evaluated by performing a simultaneous unbinned maximumlikelihood fit to the M B distributions in the range [4.6, 5.8] GeV/c 2 of the four samples corresponding to different BDT bins. In each bin, the data are described by the sum of a signal and a background component. The background shape is modelled by the upper tail of a reversed CB function, whose peak position and tail parameters are shared among BDT bins. For the determination of the systematic uncertainties, different sets of constrained parameters or alternative background models, such as the sum of two Gaussian functions, are considered. The signal shapes are described by double-sided Hypatia functions [33] whose parameters are initialized to the values obtained from a fit to the B 0 s → τ ± µ ∓ and B 0 → τ ± µ ∓ simulated samples and allowed to vary within Gaussian constraints accounting for possible discrepancies between data and simulation. The width of the Hypatia functions are ∼ 330 MeV/c 2 for both signal modes in the most sensitive BDT bin. As the separation between B 0 s → τ ± µ ∓ and B 0 → τ ± µ ∓ signal shapes is limited, two independent fits are performed while assuming the contribution of either the B 0 s or  Fig. 3. The fit procedure is validated by performing fits to a set of pseudoexperiments where the mass distributions are randomly generated according to the background model observed in the data. The pulls of all fitted parameters are normally distributed except those of the signal yields N sig, which have the expected widths but exhibit a very small bias of −3 ± 1 (2 ± 2) events for the B 0 s (B 0 ) mode. This effect is accounted for by adding the bias to N sig in the simultaneous fits to the four BDT regions for both B 0 and B 0 s. The obtained signal yields are where the uncertainties account for the statistical ones as well as those on the signal and background shape parameters. They show no evidence of any signal excess.
Using the calculated values of the normalisation factors α norm and α norm s from Eq. 1 together with Eq. 3, the observed yields from the likelihood fits are translated into upper limits on the branching fractions using the CLs method [34,35]. The total uncertainty on the normalisation factor is accounted for as an additional Gaussian constraint in the simultaneous fit. Furthermore, a systematic uncertainty on the signal yield of 34 (41) for the B 0 s (B 0 ) mode, derived using different sets of constrained parameters or alternative. The corresponding limits on the B 0 s and B 0 branching fractions at 90% and 95% CL are given in Table 1 assuming negligible contribution from the B 0 → a 1 (1260) − µ + ν µ mode. A possible residual contribution of this background would lower the expected limits by ∼16% × (B(B 0 → a 1 (1260) − µ + ν µ )/10 −4 ). The impact of systematic uncertainties on the final limits is about 35%, dominated by the uncertainty on the background model.
These results represent the best upper limits to date. They constitute a factor ∼2 improvement with respect to the BaBar result for the B 0 mode [13] and the first measurement for the B 0 s mode. The allowed range on the B 0 s → τ ± µ ∓ branching fraction preferred by the three-site Pati-Salam model [7,8] is significantly reduced by the results presented in this Letter.    [13] BaBar collaboration, B. Aubert et al., Searches for the decays B 0 → ± τ ∓ and B + → + ν ( =e, µ) using hadronic tag reconstruction, Phys. Rev. D77 (2008) 091104, arXiv:0801.0697.Over the past 30 years, William Newman has explored many artistic techniques--and one personal history.
Over the past 30 years, William Newman has explored many artistic techniques—and one personal history.
William Newman made his reputation on the street, with murals that drew the wrath of groups as disparate as the Reagan administration and the National Organization for Women. Most recently, however, the artist has been painting pictures of the birds that nested this spring outside the bathroom of the cluttered Palisades house he shares with his wife, Anne Fraser; a predominantly gray parrot, Spy; and a high-strung young French bulldog, Circe.
The recent sequence of bird paintings, The Nest, follows a set of flower canvases, the Skylight series, that is represented in the Corcoran Gallery of Art’s current retrospective, “William Newman: Peripheral Vision.” Newman hasn’t entirely abandoned the public for the private, though.
As he greets two visitors and escorts them to his second-floor studio, the shaggy-haired artist points out a proof for the 2001 piece NASA Space Mural/Hubba Bubba. He offers Oranginas from a small refrigerator filled with bottles of the drink and notes that NASA gave him five gallons of ultraviolet- and meteorite-resistant coating to safeguard the painting. “I don’t know if I want to use it for the mural or my car,” he cracks, in a voice that’s a sort of booming drawl.
Although the curators couldn’t find the space for this mural, the retrospective offers an outline of the artist’s entire career, from 1972 to 2002. Most of the 30 works are paintings, at least in part. Newman and what he calls his “very talented painting assistants” use a traditional technique, layering translucent color glazes atop monochromatic underpainting, just as Vermeer once did. Yet Newman was also one of the first artists to use a Macintosh, and many of his latest pieces are derived from either video images or computer “morphing” software.
Many artists change their styles as they age, but maturation isn’t the only reason for the domestic scale and novel techniques of the 54-year-old painter’s later art. In 1979, Newman was diagnosed with multiple sclerosis, and these days he navigates his house and studio—and the Corcoran College of Art and Design, where he’s taught since 1973—in a motorized wheelchair.
“I used to do everything completely by myself,” Newman says. In 1976, he completed a 6-by-7-foot portrait of Jimmy Carter for an inaugural ball at the Corcoran in just 96 hours. By then, he’d already demonstrated his productivity with a 1975-1976 series of murals depicting Corcoran student and life-studies model Sarah Tuft. The District’s daily newspapers excitedly reported on the first one: a 24-by-5-foot painting of a reclining and nearly nude Tuft, meant to divert construction workers at a building site near the Corcoran. (The painting was inside the site, but a peephole was thoughtfully provided for passers-by.) The mural, later dubbed Lady Sarah, featured a tempera-paint bikini that would wash away in the first major rain. But the bathing suit lasted as long as the mural, which was soon taken down.
Newman did two more outdoor Sarahs: Sarah Claus, at a building site at 18th Street and Pennsylvania Avenue NW, and Sarah and Strawberry Shortcake, for the Third Edition restaurant in Georgetown. The first painting featured a wash-away Santa suit, but the dry snow that winter didn’t do the job. So some Corcoran students in firefighter outfits, with Newman’s blessing, hosed down the mural. The second work was approved and then contested by the federal Commission of Fine