4,162 research outputs found
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
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
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
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
Model-independent search for CP violation in D0→K−K+π−π+ and D0→π−π+π+π− decays
No full textA search for CP violation in the phase-space structures of D0 and View the MathML source decays to the final states K−K+π−π+ and π−π+π+π− 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+π−π+ 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 π−π+π+π− 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
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
Properties of CP violation in neutrino-antineutrino oscillations
No full textIf the massive neutrinos are the Majorana particles, the unavoidable question of how to pin down the Majorana CP-violating phases will eventually become relevant to future neutrino experiments. We argue that a study of neutrino-antineutrino oscillations will greatly help in this regard, although the issue remains purely academic at present. In this work, we first derive the probabilities and CP-violating asymmetries of neutrino-antineutrino oscillations in the three-flavor framework, and then illustrate their properties in two special cases: the normal neutrino mass hierarchy with m(1)=0 and the inverted neutrino mass hierarchy with m(3)=0. We demonstrate the significant contributions of the Majorana phases to the CP-violating asymmetries, even in the absence of the Dirac phase. DOI:10.1103/PhysRevD.87.053019http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000316674600005&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)8ARTICLE5null8
Search for New Physics in CP-violating B Decays
No full textWe consider three possible scenarios of new physics in B 0 d - ¯ B 0 d mixing and propose a simple framework for analyzing their effects. This framework allows us to study the CP asymmetry in semileptonic B d decays (A SL ) and those in nonleptonic transitions such as B d ! J=/K S and B d ! ß + ß 0 . Numerically we find that new physics may enhance the magnitude of A SL up to the percent level within the appropriate parameter space. So measurements of A SL and its correlation with other CP asymmetries will serve as a sensitive probe for new physics in B 0 d - ¯ B 0 d mixing. PACS number(s): 11.30.Er, 12.15.Ff, 13.25.+m 3 Electronic address: [email protected] y Electronic address: [email protected] 1 Introduction The B-meson factories under construction at KEK and SLAC will provide a unique opportunity to study CP violation in weak B decays. One type of CP -violating signals, arising from B 0 d - ¯ B 0 d mixing, is expected to manifest ..
Measurement of the CP violating phase φs in Bs0→J/f0(980)
No full textMeasurement of mixing-induced CP violation in decays is of prime importance in probing new physics. 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
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