Measurement of polarization amplitudes and CP asymmetries in B 0 → ϕK *(892)0

Abstract

An angular analysis of the decay B 0 → φK * (892) 0 is reported based on a pp collision data sample, corresponding to an integrated luminosity of 1.0 fb −1 , collected at a centre-of-mass energy of √ s = 7 TeV with the LHCb detector. The P-wave amplitudes and phases are measured with a greater precision than by previous experiments, and confirm about equal amounts of longitudinal and transverse polarization. The S-wave K + π − and K + K − contributions are taken into account and found to be significant. A comparison of the B 0 → φK * (892) 0 and B 0 → φK * (892) 0 results shows no evidence for direct CP violation in the rate asymmetry, in the triple-product asymmetries or in the polarization amplitudes and phases.

Weak annihilation and new physics in charmless $$\varvec{B\rightarrow M M}$$ B → M M decays

“…Concerning B → K * φ, we include in addition also available measurements of relative amplitude phases φ ⊥, (purple). The combined allowed region from all observables does not overlap with regions from only branching fractions nor only amplitude phases at 68% probability, giving rise to large pull values of the branching fraction B(B 0 → K * 0 φ): 1.7σ from BaBar [36] and 2.6σ from Belle [37]; for C L (B − → K * − φ) of −1.5σ from HFAG [19]; for C ⊥ (B 0 →K * 0 φ) of 1.2σ from Belle [37], but not for BaBar (0.2σ) and LHCb (−0.6σ); and for φ ⊥ (B 0 →K * 0 φ) of 1.1σ from LHCb [38], but not for BaBar and Belle (both 0.0σ). However, the p value of 0.95 of the fit is very high as we include many other measurements that are described consistently in the fit.…”

ProbingCPviolation systematically in differential distributions

“…A significant amount of effort, both theoretical and experimental has been devoted to their study. A triple-product asymmetry has been measured in K L → π + π − e + e − [9] and applications are also found in heavy-meson [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] [27][28][29][30][31], baryon [32,33], top [34], Z [35], Higgs [36][37][38][39], and beyond-the-standard-model [40] physics.…”

“…Actually, when the form of the differential decay rate is known with confidence, one may rely on an unbinned likelihood fit to the data for extracting CP-violating parameters. Such amplitude analyses have notably been carried out for several B-meson decays: e.g., for B 0 s → K + K − K + K − , dominated by a φφ intermediate state [29], or for B 0 → K + K − K + π − , dominated by a φK * 0 resonant intermediate state [27,31].…”

Charmless B decays at LHCb

“…The fits to the mass spectra are shown in Figure 1, and the yields are determined to be 2349 ± 49 B 0 s → φ φ decay candidates and 6680 ± 86 B 0 → φ K * 0 decay candidates. The yields are corrected for non-resonant contributions determined from angular analyses [5,10]. The ratio of branching ratios of the signal and normalisation mode is determined to be 1.84 ± 0.05 (stat) ± 0.07 (syst) ± 0.11 ( f s / f d ).…”

“…The decay decay B 0 → φ φ is highly suppressed and the SM predictions are in the range 0.1 − 3 × 10 −8 but could be enhanced in some extensions to the SM. The previous best limit for this mode is B(B 0 → φ φ ) < 2.0 × 10 −7 at 90% CL set by the BaBar Collaboration [11]. The analysis described above is extended to a search for this decay, where the main change is that the cut on the BDT output variable is optimised using a frequentist figure of merit (FoM) [12] to maximise the probability of finding the first evidence for this decay.…”