Nuclear physics. B, Proceedings, supplements最新文献

BaBar has found $A_{\mathrm{CP}}({\tau }^{-}\to \nu K_S{\pi }^{-}[\ge {\pi }^0\left]\right)=(-0.36\pm 0.23\pm 0.11)\text{\%}$ with 2.8 σ difference with SM prediction $A_{\mathrm{CP}}({\tau }^{-}\to \nu K_S{\pi }^{-})=(0.36\pm 0.01)\text{\%}$ based on $K^0-{\overline{K}}^0$ oscillation. Four central points: (i) to establish both the ‘existence’ of New Dynamics (ND) and its ‘features’ in local CP asymmetries; (ii) to increase the number of final states to be probed; (iii) to emphasize correlations of CP violations between different final states; (iv) likewise for the correlations with $D^{\pm }$ final states. These measurements should be possible at SuperB & Belle II experiments.

We discuss new physics that can show up in the ${\tau }^{+}{\tau }^{-}$ production process at the LHC but not in the dimuon or the dielectric channels. We consider three different generic possibilities: a new resonance in the Drell-Yan process in the form of a non-universal $Z^{\prime }$; a new non-resonant contribution to $q\overline{q}\to {\tau }^{+}{\tau }^{-}$ in the form of leptoquarks; and contributions from gluon fusion due to effective lepton gluonic couplings. We emphasize the use of the charge asymmetry both to discover new physics and to distinguish between different possibilities

The leading-order hadronic contribution to the muon magnetic anomaly $a_{\mu }\equiv (g_{\mu }-2)/2$, calculated using a dispersion integral of $e^{+}{e}^{-}$ annihilation data and τ decay data, is briefly reviewed. This contribution has the largest uncertainty to the predicted value of $a_{\mu }$, which differs from the experimental value by ∼ 3.6 (2.4) standard deviations for the $e^{+}{e}^{-}$ (τ) based analysis. New results since the last workshop and main open issues on the subject are discussed.

In this proceeding, a search for a Higgs boson in the H to ${\tau }^{+}{\tau }^{-}$ decay mode, where both taus decay hadronically or one decay hadronically and one leptonically. The analysis is based on a data sample of proton-proton collision collected by the ATLAS detector at the Large Hadron Collider (LHC) at centre-of-mass energies of 7 TeV during 2011, corresponding to an integrated luminosity of $4.7f{b}^{-1}$. No significant excess is observed in the Higgs boson mass range of 100–150 GeV. The observed (expected) limits on the cross-section times branching ratio for H to ${\tau }^{+}{\tau }^{-}$ at $m_H=125\text{GeV}$ are 6.2(5.9) and 6.3(6.5) for lepton-hadron and hadron-hadron decay modes, respectively.

We report on the first searches for lepton flavour violating ${\tau }^{-}$ decays at a hadron collider. These include searches for the lepton flavour violating decay ${\tau }^{-}\to {\mu }^{+}{\mu }^{-}{\mu }^{-}$ and the lepton flavour and baryon number violating decays ${\tau }^{-}\to \overline{p}{\mu }^{+}{\mu }^{-}$ and ${\tau }^{-}\to p{\mu }^{-}{\mu }^{-}$. Using 1.0 fb⁻¹ of data collected at $\sqrt{s}=7\text{TeV}$ by LHCb in 2011 upper limits of $B({\tau }^{-}\to {\mu }^{+}{\mu }^{-}{\mu }^{-})<7.8\left(6.3\right)\times {10}^{-8}$, $B({\tau }^{-}\to \overline{p}{\mu }^{+}{\mu }^{-})<4.5\left(3.4\right)\times {10}^{-7}$ and $B({\tau }^{-}\to p{\mu }^{-}{\mu }^{-})<6.0\left(4.6\right)\times {10}^{-7}$ are set at 95% (90%) confidence level.

In many new physics extensions of the Standard Model, light pseudoscalar Higgs or dark matter candidates naturally appear. Searches for light and dark Higgs bosons performed with the large $e^{+}{e}^{-}$ datasets collected by the BaBar experiment at center-of-mass energies around the ϒ resonances are presented.

In these proceedings a search for neutral Higgs bosons in the Minimal Supersymmetric Standard Model in the decay modes h/A/H to ${\tau }^{+}{\tau }^{-}$ is reported. This search is performed using 4.7 fb⁻¹ of integrated luminosity of pp collision data collected at the Large Hadron Collider at $\sqrt{s}=7\text{TeV}$ during 2011. Upper limits on the cross-section times branching ratio, for both b-associated and gluon-fusion production modes, are derived for the Higgs mass range of 90–500 GeV. Exclusion limits are also shown in the $m_A-\tan \beta$ plane for the $m_h^{\max }$ scenario with $\mu >0$.

The past year has been very exciting for neutrino physics. The last mixing angle, ${\theta }_{13}$, has been measured by a number of experiments and is quite large. These experiments will, hopefully, continue reducing systematic and statistical errors in anticipation of statistically significant CP violation experiments. At Fermilab, MiniBooNE has finished its data run and has new results for electron antineutrino excesses; MINOS has done a combined fit for their ${\nu }_{\mu }$ disappearance measurements for neutrinos and antineutrinos (which are now consistent) and presented results for a sterile neutrino search; and Minerνa has presented its first cross section results.

The main highlights discussed at TAU2012 are briefly summarized. Besides the standard topics on lepton physics covered also at previous conferences (universality, QCD tests, $V_{us}$ determination from τ decay, $g-2$, ν oscillations, lepton-flavour violation), the τ lepton is playing now a very important role in searches for new physics phenomena.

In this proceedings, the first measurement of τ polarization at a hadron collider is presented. The method for extracting the τ polarization is independent of the mode of τ production and can be applied to the characterization of new phenomena at the Large Hadron Collider. The method has been applied to $W\to \tau \nu$ decays and the measured value of is in agreement with the Standard Model prediction.