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The objective of this first workshop on Multiple Partonic Interactions (MPI) at the LHC is to raise the profile of MPI studies, summarizing the legacy from the older phenomenology at hadronic colliders and favouring further specific contacts between the theory and experimental communities. The MPI are experiencing a growing popularity and are currently widely invoked to account for observations that would not be explained otherwise: the activity of the Underlying Event, the cross sections for multiple heavy flavour production, the survival probability of large rapidity gaps in hard diffraction, etc. At the same time, the implementation of the MPI effects in the Monte Carlo models is quickly proceeding through an increasing level of sophistication and complexity that in perspective achieves deep general implications for the LHC physics....
This report describes the present status of the detector design for SuperB. It is one of four separate progress reports that, taken collectively, describe progress made on the SuperB Project since the publication of the SuperB Conceptual Design Report in 2007 and the Proceedings of SuperB Workshop VI in Valencia in 2008. The other three reports relate to Physics, Accelerator and Computing.
Using data collected with the LHCb detector in proton–proton collisions at a centre-of-mass energy of 7 TeV, the semileptonic decays B¯s0→Ds*Xμ-v¯ and B¯s0→D0K+Xμ-v¯ are detected. Two structures are observed in the D0K+ mass spectrum at masses consistent with the known Ds1+(2536) and Ds2*(2573)+ mesons. The measured branching fractions relative to the total B¯s0 semileptonic rate are B(B¯s0→Ds2*+Xμ-v¯)/B(B¯s0→D0→Xμ-v¯)=(3.3±1.0±0.4)%, B(B¯s0→Ds1*+Xμ-v¯)/B(B¯s0→D0→Xμ-v¯)= (5.4±1.2±0.5)%, where the first uncertainty is statistical and the secon...
We present a measurement of the time-dependent CP-violating asymmetry in Bs0→J/ψϕ decays, using data collected with the LHCb detector at the LHC. The decay time distribution of Bs0→J/ψϕ is characterized by the decay widths ΓH and ΓL of the heavy and light mass eigenstates, respectively, of the Bs0-B̅ s0 system and by a CP-violating phase ϕs. In a sample of about 8500 Bs0→J/ψϕ events isolated from 0.37  fb-1 of pp collisions at √s=7  TeV, we measure ϕs=0.15±0.18(stat)±0.06(syst)  rad. We also find an average Bs0 decay width Γs≡(ΓLH)/2=0.657±0.009(stat)±0.008(syst)  ps-1 and a decay width difference ΔΓs≡ΓLH=0.123±0.029(stat)±0.011(syst)  ps-1. Our measurement is insensitive to the transformation (ϕs,ΔΓs)...
So far only the channel has been used. Here we report on a measurement using an LHCb data sample of 0.41 fb−1, in the CP odd eigenstate J/ψf0(980), where f0(980)→π+π−. A time-dependent fit of the data with the lifetime and the difference in widths of the heavy and light eigenstates constrained to the values obtained from yields a value of the CP violating phase of −0.44±0.44±0.02 rad, consistent with the Standard Model expectation.
A search for the decays View the MathML source and B0→μ+μ− is performed with 0.37 fb−1 of pp collisions at View the MathML source collected by the LHCb experiment in 2011. The upper limits on the branching fractions are View the MathML source and B(B0→μ+μ−)<3.6×10−9 at 95% confidence level. A combination of these results with the LHCb limits obtained with the 2010 dataset leads to View the MathML source and B(B0→μ+μ−)<3.2×10−9 at 95% confidence level.
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