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Abstract:

Different search strategies for supersymmetry have been employed by the LHC general-purpose experiments using early data. As proven by their early results, these strategies are promising, but raise the question of how well they will generalize for the future. We address this question by studying two thousand phenomenological minimal supersymmetric standard model parameter space points that come from a fit to indirect and cosmological data. We examine the 5σ discoverability of the points employing a typical ATLAS-type search based on missing transverse momentum (MET), a search based on an optimised M T2cut and a combination of the two, taking into account standard model backgrounds. The discovery reach of the strategies can depend strongly on the systematic uncertainty in the background, subject to the stringency of the cuts and the details of the background simulation. By combining the MET and MT2 based strategies, with an integrated luminosity of 1 fb -1 (10 fb-1) at 7TeV, 4-8% (42%) of the points are discoverable, depending on the systematic uncertainty on the background. At 14TeV and with 10 fb-1, 96% of the points are discoverable. While the majority of points can be discovered by both strategies at √s = 14 TeV and with 1 fb-1, there are some that are left undiscovered by a MET search strategy, but which are discovered by the MT2 strategy, and vice versa, therefore it is essential that one performs both in parallel. We discuss some of the factors that can make points more difficult to observe. © SISSA 2011.

Abstract:

We present a study of Bs0 decays to the CP-odd final state J/ψf 0(980) with J/ψ→μ+μ- and f 0(980)→π+π-. Using pp̄ collision data with an integrated luminosity of 3.8fb-1 collected by the CDF II detector at the Tevatron we measure a Bs0 lifetime of τ(Bs0→J/ψf0(980))=1.70-0.11+0.12(stat)±0.03(syst) ps. This is the first measurement of the Bs0 lifetime in a decay to a CP eigenstate and corresponds in the standard model to the lifetime of the heavy Bs0 eigenstate. We also measure the product of branching fractions of Bs0→J/ψf0(980) and f0(980)→π +π- relative to the product of branching fractions of Bs0→J/ψ and →K+K- to be Rf0 /=0.257±0.020(stat)±0.014(syst), which is the most precise determination of this quantity to date. © 2011 American Physical Society.

Abstract:

Branching fractions of the decays $H_b\to H_c\pi^-\pi^+\pi^-$ relative to $H_b\to H_c\pi^-$ are presented, where $H_b$ ($H_c$) represents B^0-bar($D^+$), $B^-$ ($D^0$), B_s^0-bar ($D_s^+$) and $\Lambda_b^0$ ($\Lambda_c^+$). The measurements are performed with the LHCb detector using 35${\rm pb^{-1}}$ of data collected at $\sqrt{s}=7$ TeV. The ratios of branching fractions are measured to be B(B^0-bar -> D^+\pi^-\pi^+\pi^-)/ B(B^0-bar -> D^+\pi^-) = 2.38\pm0.11\pm0.21 B(B^- -> D^0\pi^-\pi^+\pi^-) / B(B^- -> D^0\pi^-) = 1.27\pm0.06\pm0.11 B(B_s^0-bar -> D_s^+\pi^-\pi^+\pi^-) / B(B_s^0-bar -> D_s^+\pi^-) = 2.01\pm0.37\pm0.20 B(\Lambda_b^0->\Lambda_c^+\pi^-\pi^+\pi^-) / B(\Lambda_b^0 -> \Lambda_c^+\pi^-) = 1.43\pm0.16\pm0.13. We also report measurements of partial decay rates of these decays to excited charm hadrons. These results are of comparable or higher precision than existing measurements.