9 research outputs found

    CMS physics technical design report : Addendum on high density QCD with heavy ions

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    First measurement of time-dependent CP violation in Bs0K+K B_s^0\to K^+K^- decays

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    Direct and mixing-induced CP-violating asymmetries in B-s(0) -> K+K- decays are measured for the first time using a data sample of p p collisions, corresponding to an integrated luminosity of 1.0 fb(-1), collected with the LHCb detector at a centre-of-mass energy of 7 TeV. The results are C-KK = 0.14 +/- 0.11 +/- 0.03 and S-KK = 0.30 +/- 0.12 +/- 0.04, where the first uncertainties are statistical and the second systematic. The corresponding quantities are also determined for B-0 -> pi(+)pi(-) decays to be C-pi pi = -0.38 +/- 0.15 +/- 0.02 and S-pi pi = -0.71 +/- 0.13 +/- 0.02, in good agreement with existing measurements

    Measurement of the charge asymmetry in B-+/- -> phi K +/- and search for B-+/- -> phi pi(+/-) decays

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    The CP-violating charge asymmetry in B-+/- -> phi K-+/- decays is measured in a sample of pp collisions at 7 TeV centre-of-mass energy, corresponding to an integrated luminosity of 1.0 fb-1 collected by the LHCb experiment. The result is A(CP)(B-+/- -> phi K-+/-) = 0.022 +/- 0.021 +/- 0.009, where the first uncertainty is statistical and the second systematic. In addition, a search for the B-+/- -> phi pi(+/-) decay mode is performed, using the B-+/- -> phi K-+/- decay rate for normalization. An upper limit on the branching fraction B(B-+/- -> phi pi(+/-)) < 1.5 x 10(-7) is set at 90% confidence level. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved

    Observation of the decay B-s(0) -> (D)over-bar(0)phi

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    First observation of the decay B-s(0) -> (D) over bar (0)phi is reported using pp collision data, corresponding to an integrated luminosity of 1.0 fb(-1), collected by the LHCb experiment at a centre-of-mass energy of 7 TeV. The significance of the signal is 6.5 standard deviations. The branching fraction is measured relative to that of the decay B-S(0) -> (D) over bar (0)phi to be beta B-S(0) -> (D) over bar (0)phi/beta B-S(0) -> (D) over bar (0)(K) over bar*(0) = 0.069 +/- 0.013 (stat) +/- 0.007 (syst). The first measurement of the ratio of branching fractions for the decays beta B-S(0) -> (D) over bar (0)(K) over bar*(0) and beta B-S(0) -> (D) over bar (0)(K) over bar*(0) is found to be beta B-S(0) -> (D) over bar (0)(K) over bar*(0/)beta B-S(0) -> (D) over bar (0)(K) over bar*(0=7.8) +/- 0.7(stat) +/- 0.3 (syst) +/- 0.6 (f(s)/f(d)) where the last uncertainty is due to the ratio of the B(s)(0)and B-0 fragmentation fractions

    Search for the decay D-0 -> pi(+)pi(-)mu(+)mu(-)

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    A search for the D-0 -> pi(+)pi(-)mu(+)mu(-) decay, where the muon pair does not originate from a resonance, is performed using proton-proton collision data corresponding to an integrated luminosity of 1.0 fb(-1) recorded by the LHCb experiment at a centre-of-mass energy of 7 TeV. No signal is observed and an upper limit on the relative branching fraction with respect to the resonant decay mode D-0 -> pi(+)pi(-)phi(-> mu(+)mu(-)), under the assumption of a phase-space model, is found to be B(D-0 -> pi(+)pi(-)mu(+)mu(-))/B(D-0 -> pi(+)pi(-)phi(-> mu(+)mu(-))) pi(+)pi(-)mu(+)mu(-)) < 5.5 x 10(-7) at 90% confidence level. This is the most stringent to date

    Measurement of the flavour-specific CP-violating asymmetry a(sl)(s) in B-s(0) decays

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    The CP-violating asymmetry a(sl)(s), is studied using semileptonic decays of B-s(0) and (B) over bar (0)(s) mesons produced in pp collisions at a centre-of-mass energy of 7 TeV at the LHC, exploiting a data sample corresponding to an integrated luminosity of 1.0 fb(-1). The reconstructed final states are D-s(+/-)mu(+/-)(s), with the D-s(+/-) particle decaying in the phi pi(+/-) mode. The D-s(+/-)mu(+/-)(s) yields are summed over B-s(0) and (B) over bar (0)(s) initial states, and integrated with respect to decay time. Data-driven methods are used to measure efficiency ratios. We obtain a(sl)(s) = (-0.06 +/- 0.50 +/- 0.36)%, where the first uncertainty is statistical and the second systematic

    Model-independent search for CP violation in D-0 > K-K+pi(-)pi(+) and D-0 -> pi(-)pi(+)pi(+)pi(-) decays

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    A search for CP violation in the phase-space structures of 130 and 15 decays to the final states K-K+pi(-)pi(+) and pi(-)pi(+)pi(+)pi(-) is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0 fb(-1) collected in 2011 by the LHCb experiment in pp collisions at a centre-of-mass energy of 7 TeV. For the K-K+pi(-)pi(+) final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the pi(-)pi(+)pi(+)pi(-). final state is partitioned into 128 bins, each bin with approximately 2500 decays. The p-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity

    CMS physics technical design report: Addendum on high density QCD with heavy ions

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    This report presents the capabilities of the CMS experiment to explore the rich heavy-ion physics programme offered by the CERN Large Hadron Collider (LHC). The collisions of lead nuclei at energies ,will probe quark and gluon matter at unprecedented values of energy density. The prime goal of this research is to study the fundamental theory of the strong interaction - Quantum Chromodynamics (QCD) - in extreme conditions of temperature, density and parton momentum fraction (low-x). This report covers in detail the potential of CMS to carry out a series of representative Pb-Pb measurements. These include "bulk" observables, (charged hadron multiplicity, low pT inclusive hadron identified spectra and elliptic flow) which provide information on the collective properties of the system, as well as perturbative probes such as quarkonia, heavy-quarks, jets and high pT hadrons which yield "tomographic" information of the hottest and densest phases of the reaction.0info:eu-repo/semantics/publishe

    Search for top quark partners with charge 5/3 in the same-sign dilepton and single-lepton final states in proton-proton collisions at s=13 \sqrt{s}=13 TeV

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