Sneha Malde

Abstract:

Using (27.12 ± 0.14) × 108ψ(3686) events collected by the BESIII detector at the center-of-mass energy of s = 3.686 GeV, we search for the first time for two nonleptonic hyperon decays that change strangeness by two units, Ω− → Σ0π− and Ω− → nK−. No significant signal is observed. The upper limits on their decay branching fractions are determined to be B(Ω− → Σ0π−) < 5.4 × 10−4 and B(Ω− → nK−) < 2.4 × 10−4 at the 90% confidence level.

Abstract:

The ratio of branching fractions between B0 → J/ψπ0 and B+ → J/ψK*+ decays is measured with proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1. The measured value isBB0→J/ψπ0BB+→J/ψK∗+=1.153±0.053±0.048×10−2, where the first uncertainty is statistical and the second is systematic. The branching fraction for B0 → J/ψπ0 decays is determined using the branching fraction of the normalisation channel, resulting inBB0→J/ψπ0=1.670±0.077±0.069±0.095×10−5, where the last uncertainty corresponds to that of the external input. This result is consistent with the current world average value and competitive with the most precise single measurement to date.

Abstract:

The first search for nonresonant Bc+→π+μ+μ- decays is reported. The analysis uses proton–proton collision data collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9fb-1. No evidence for an excess of signal events over background is observed and an upper limit is set on the branching fraction ratio B(Bc+→π+μ+μ-)/B(Bc+→J/ψπ+)<2.1×10-4 at 90% confidence level. Additionally, an updated measurement of the ratio of the Bc+→ψ(2S)π+ and Bc+→J/ψπ+ branching fractions is reported. The ratio B(Bc+→ψ(2S)π+)/B(Bc+→J/ψπ+) is measured to be 0.254±0.018±0.003±0.005, where the first uncertainty is statistical, the second systematic, and the third is due to the uncertainties on the branching fractions of the leptonic J/ψ and ψ(2S) decays. This measurement is the most precise to date and is consistent with previous LHCb results.