3,417 research outputs found
Branching fraction and CP asymmetry of the decays B+→K0Sπ+ and B+→K0SK+
No full textAn analysis of B+ → K0
Sπ+ and B+ → K0
S K+ decays is performed with the LHCb experiment. The pp
collision data used correspond to integrated luminosities of 1 fb−1 and 2 fb−1 collected at centre-ofmass
energies of
√
s = 7 TeV and
√
s = 8 TeV, respectively. The ratio of branching fractions and the
direct CP asymmetries are measured to be B(B+ → K0
S K+
)/B(B+ → K0
Sπ+
) = 0.064 ± 0.009 (stat.) ±
0.004 (syst.), ACP(B+ → K0
Sπ+
) = −0.022 ± 0.025 (stat.) ± 0.010 (syst.) and ACP(B+ → K0
S K+
) =
−0.21 ± 0.14 (stat.) ± 0.01 (syst.). The data sample taken at
√
s = 7 TeV is used to search for
B+
c
→ K0
S K+ decays and results in the upper limit ( fc · B(B+
c
→ K0
S K+
))/( fu · B(B+ → K0
Sπ+
)) <
5.8 × 10−2 at 90% confidence level, where fc and fu denote the hadronisation fractions of a ¯b
quark
into a B+
c or a B+ meson, respectively
Measurement of the time-dependent CP asymmetry in B0 -> J/ψ KS0 decays
No full textThis Letter reports a measurement of the CP violation observables SJ/ψK0S and CJ/ψK0S in the decay channel B0→J/ψK0S performed with 1.0 fb−1 of pp collisions at s√=7 TeV collected by the LHCb experiment. The fit to the data yields SJ/ψK0S=0.73±0.07(stat)±0.04(syst) and CJ/ψK0S=0.03±0.09(stat)±0.01(syst). Both values are consistent with the current world averages and within
expectations from the Standard Model
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
No full textMeasurement of the mixing-induced CP-violating phase phi_s in Bs decays is of prime importance in probing new physics. Here 7421 +/- 105 signal events from the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A time-dependent fit to the data yields a value of phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard Model expectation. No evidence of direct CP violation is found
Implementation of supersymmetric processes in the HERWIG event generator
No full textWe describe the implementation of supersymmetric processes in the HERWIG Monte Carlo event generator. We define relevant parameter and mixing conventions and list the hard scattering matrix elements. Our implementation is based on the Minimum Supersymmetric Standard Model, with the option of R-parity violation. The sparticle spectrum is completely general. Both hadron-hadron and lepton-lepton collisions are covered. This article supplements a separate publication in which the general features of HERWIG 6.2 are described, and updates the treatment of supersymmetry to version 6.4
Search for CP violation in the decay D+→π−π+π+
No full textA search for CP violation in the phase space of the decay D+→π−π+π+ 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 Dalitz plot distributions for 3.1×106D+ and D− candidates are compared with binned and unbinned model-independent techniques. No evidence for CP violation is found
A study of CP violation in B±→DK±B±→DK± and B±→Dπ±B±→Dπ± decays with D→KS0K±π∓ final states
No full textA first study of CP violation in the decay modes B± → [K0S K ±π∓]Dh± and B± → [K0S K ∓π±]Dh±, where h labels a K or π meson and D labels a D0 or D0 meson, is performed. The analysis uses the LHCb data set collected in pp collisions, corresponding to an integrated luminosity of 3 fb−1. The analysis is sensitive to the CP-violating CKM phase γ through seven observables: one charge asymmetry in each of the four modes and three ratios of the charge-integrated yields. The results are consistent with measurements of γ using other decay modes
Measurement of mixing and CP violation parameters in two-body charm decays
No full textA study of mixing and indirect CP violation in D 0 mesons through the determination of the parameters y CP and A Γ is presented. The parameter y CP is the deviation from unity of the ratio of effective lifetimes measured in D 0 decays to the CP eigenstate K + K − with respect to decays to the Cabibbo favoured mode K −π+. The result measured using data collected by LHCb in 2010, corresponding to an integrated luminosity of 29 pb−1, is y CP = (5.5 ± 6.3stat ± 4.1syst) × 10−3. The parameter A Γ is the asymmetry of effective lifetimes measured in decays of D 0 and D0 mesons to K + K −. The result is A Γ = (−5.9 ± 5.9stat ± 2.1syst) × 10−3. A data-driven technique is used to correct for lifetime-biasing effects
Search for CP violation in D + → ϕπ + and D+s→K0Sπ+ decays
No full textA search for CP violation in D + → ϕπ + decays is performed using data collected in 2011 by the LHCb experiment corresponding to an integrated luminosity of 1.0 fb−1 at a centre of mass energy of 7 TeV. The CP -violating asymmetry is measured to be (−0.04 ± 0.14 ± 0.14)% for candidates with K − K + mass within 20 MeV/c 2 of the ϕ meson mass. A search for a CP -violating asymmetry that varies across the ϕ mass region of the D + → K − K + π + Dalitz plot is also performed, and no evidence for CP violation is found. In addition, the CP asymmetry in the D+s→K0Sπ+ decay is measured to be (0.61 ± 0.83 ± 0.14)%
Measurement of the CP-violating phase phi(s) in (B)over-bar(s)(0) -> J / psi pi(+)pi(-) decays
No full textThe mixing-induced CP -violating phase ϕs in View the MathML source and View the MathML source decays is measured using the J/ψπ+π− final state in data, taken from 3 fb−1 of integrated luminosity, collected with the LHCb detector in 7 and 8 TeV centre-of-mass pp collisions at the LHC. A time-dependent flavour-tagged amplitude analysis, allowing for direct CP violation, yields a value for the phase ϕs=70±68±8 mrad. This result is consistent with the Standard Model expectation and previous measurements
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CP violation
No full textIn this talk the author briefly reviews the cosmological importance of CP violation and the status of calculations of baryogenisis in the context of the Standard Model. The author then turns to a discussion of Standard Model Predictions for CP violation in B decays, stressing the importance of multiple measurements to overconstrain the model parameters and thus search for indications of beyond-Standard-Model physics
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