$W^+W^-$ background for two combinations of beam polarisations $P_{e^-},P_{e^+}$: (a) $-$80%,+80%, (b) +80%,$-$80%). (c) Difference of $e^+$ and $e^-$ energy spectra from selectrons $\tilde{e}_{L,R}$ produced with polarised beams; from [@nauenberg]](epLemR.ps "fig:"){width="4cm" height="3cm"}  (c)

![(a,b) Energy spectra of muons from $\tilde{\mu}_{L,R}$ decays into $\mu\tilde{\chi}^0_1$ including $W^+W^-$ background for two combinations of beam polarisations $P_{e^-},P_{e^+}$: (a) $-$80%,+80%, (b) +80%,$-$80%). (c) Difference of $e^+$ and $e^-$ energy spectra from selectrons $\tilde{e}_{L,R}$ produced with polarised beams; from [@nauenberg]](nau3.eps){width="7cm" height="6cm"}

. \[fig:pol\]

Polarisation is a very powerful tool not only for preparing the desirable initial state, but also as a diagnosis tool of final states. At this meeting improvements of exploiting information on polarisation of fermions coming from decays of scalar particles (Higgs, sfermions) have been reported [@Boos:2005ca; @Godbole:2004mq]. The charged Higgs boson couples strongly to the fermions of the third generation. If the charged Higgs is rather light ($M_{H^{\pm}}<M_t$), it decays dominantly to a tau lepton and neutrino ($H^{\pm} \to \tau^{\pm} \nu$) making its mass reconstruction impossible. The main background comes from decays $W^\pm \to \tau^\pm \nu$. However, different structure of $H^{\pm}$ and $W^{\pm}$ electroweak interactions implies different tau polarization[^2], which is reflected in the energy spectra of the $\tau^{\pm}$ decay products, see e.g. 