7,792 research outputs found
Branching fraction and CP asymmetry of the decays B+→K0Sπ+ and B+→K0SK+
Get PDFAn 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
Get PDFThis 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
Get PDFMeasurement 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
Higher order and CP-violating effects in the neutralino and Higgs boson sectors of the MSSM
Get PDFComplete one-loop results are presented for neutralino and Higgs decay processes of the form chi^0_i->chi^0_j h_a and h_a->chi^0_i chi^0_j in the MSSM with CP-violating parameters. An on-shell renormalisation scheme is developed for the chargino–neutralino sector that consistently takes into account imaginary parts arising from complex parameters and absorptive parts of loop integrals. The genuine vertex contributions are combined with two-loop Higgs propagator-type corrections to obtain the most precise
prediction currently available for this class of processes. In the CP-violating CPX benchmark scenario, the corrections to the neutralino decay width are found to be particularly large – of order 45% for a Higgs mass of 40GeV. We find that in this unexcluded parameter region, which will be difficult to cover by standard Higgs search channels
at the LHC, the branching ratio for the decay chi^0_2->chi^0_1 h_1 is large. This may offer good prospects of detecting such a light Higgs boson in cascade decays of supersymmetric particles. We also study the full Higgs production and decay processes in scenarios where the intermediate Higgs bosons are nearly mass degenerate and interference effects can have a significant impact. We find that an on-shell approximation gives results in good numerical agreement with the full momentum-dependent Higgs propagator matrix calculation and we develop a generalised
narrow width approximation to be used in such a situation. We use these methods to study the asymmetry between the production of left-handed and right-handed neutralinos in Higgs decays at the LHC in the presence of CP-violating phases. Large asymmetries are found to be possible for large M_H^± > 500GeV and tan beta < 10, where the decay
into neutralinos may be the only possibility to detect the heavy Higgs bosons
A study of CP violation in B±→DK±B±→DK± and B±→Dπ±B±→Dπ± decays with D→KS0K±π∓ final states
Get PDFA 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
A4 and CP symmetry and a model with maximal CP violation
No full textAbstractWe study a second CP symmetry compatible with the A4 flavor group, which interchanges the representations 1′ and 1″. We analyze the lepton mixing patterns arising from the A4 and CP symmetry broken to residual subgroups Z3 and Z2×CP in the charged lepton and neutrino sectors respectively. One phenomenologically viable mixing pattern is found, and it predicts maximal atmospheric mixing angle as well as maximal Dirac CP phase, trivial Majorana phases and the correlation sin2θ12cos2θ13=1/3. We construct a concrete model based on the A4 and CP symmetry, the above interesting mixing pattern is achieved, the observed charged lepton mass hierarchy is reproduced, and the reactor mixing angle θ13 is of the correct order
Tri-direct CP in the littlest seesaw playground
No full textWe discuss spontaneously broken CP symmetry in two right-handed neutrino models based on the idea of having a different residual flavour symmetry, together with a different residual CP symmetry, associated with each of the two right-handed neutrinos. The charged lepton sector also has a different residual flavour symmetry. In such a tri-direct CP approach, we show that the combination of the three residual flavour and two residual CP symmetries provides a new way of fixing the parameters. To illustrate the approach, we revisit the Littlest Seesaw (LSS) model based on S4 and then propose new variants which have not so far appeared in the literature, with different predictions for each variant. We analyse numerically the predictions of the new variants, and then propose an explicit model which can realise one of the successful benchmark points, based on the atmospheric flavon vacuum alignment (1, ω2, ω) and the solar flavon vacuum alignment (1, −7/2, −7/2).</p
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