Пахлова Галина Владимировна

First Measurement of the B+ → π + π0π0 Branching Fraction and CP Asymmetry

2023 · ARTICLE · en

We study B+→π+π0π0 using 711 fb−1 of data collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We measure an inclusive branching fraction of (19.0±1.5±1.4)×10−6 and an inclusive CP asymmetry of (9.2±6.8±0.7)%, where the first uncertainties are statistical and the second are systematic, and a B+→ρ(770)+π0 branching fraction of (11.2±1.1±0.9+0.8−1.6)×10−6, where the third uncertainty is due to possible interference with B+→ρ(1450)+π0. We present the first observation of a structure around 1 GeV/c2 in the π0π0 mass spectrum, with a significance of 6.4σ, and measure a branching fraction to be (6.9±0.9±0.6)×10−6. We also report a measurement of local CP asymmetry in this structure.

Angular analysis of the low K+K− mass enhancement in B+→ K+K−π+ decays

2023 · ARTICLE · en

We study the decay B+→K+K−π+ and investigate the angular distribution of K+K− pairs with invariant mass below 1.1 GeV/c2. This region exhibits both a strong enhancement in signal and very large direct CP violation. We construct a coherent sum model for the angular distribution of S- and P-wave, and report the ratio of their amplitudes, the relative phase and the forward-backward asymmetry. We also report absolute differential branching fractions and direct CP asymmetry for the decay in bins of MK+K− and the differential branching fractions in bins of MK+π−. The results are based on a data sample that contains 772×106 BB¯ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. The measured overall branching fraction and the direct CP asymmetry are (5.38±0.40±0.35)×10−6 and −0.170±0.073±0.017, respectively, where the first uncertainties are statistical and the second are systematic.

Evidence of B0 → pΣ−π− at Belle

2023 · ARTICLE · en

We search for the B0→p¯Σ0π− decay with ¯Σ0→¯Λγ, where the γ is not measured, using a data sample corresponding to an integrated luminosity of 711 fb−1 which contains 772×106 B¯B pairs, collected around the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We measure for the first time the B0→p¯Σ0π− branching fraction to be B(B0→p¯Σ0π−)=(1.17+0.43−0.40(stat)±0.07(syst))×10−6 with a significance of 3.0σ. We simultaneously measure the branching fraction for the related channel B0→p¯Λπ− with much improved precision.

Measurement of branching fractions and decay asymmetry parameters for Λc+ → Λh+ and Λc+ → Σ0h+ (h=K,π), and search for CP violation in baryon decays

2023 · ARTICLE · en

We report a study of Λ+c→Λh+ and Λ+c→Σ0h+ (h=K,π) decays based on a data sample of 980~fb−1 collected with the Belle detector at the KEKB energy-asymmetric e+e− collider. The first results of direct CP asymmetry in two-body singly Cabibbo-suppressed (SCS) decays of charmed baryons are measured, AdirCP(Λ+c→ΛK+)=+0.021±0.026±0.001 and AdirCP(Λ+c→Σ0K+)=+0.025±0.054±0.004. We also make the most precise measurement of the decay asymmetry parameters (α) for the four modes of interest and search for CP violation via the α-induced CP asymmetry (AαCP). We measure AαCP(Λ+c→ΛK+)=−0.023±0.086±0.071 and AαCP(Λ+c→Σ0K+)=+0.08±0.35±0.14, which are the first AαCP results for SCS decays of charmed baryons. We search for Λ-hyperon CP violation in Λ+c→(Λ,Σ0)π+ and find AαCP(Λ→pπ−)=+0.013±0.007±0.011. This is the first time that hyperon CP violation has been measured via Cabibbo-favored charm decays. No evidence of baryon CP violation is found. We also obtain the most precise branching fractions for two SCS Λ+c decays, B(Λ+c→ΛK+)=(6.57±0.17±0.11±0.35)×10−4 and B(Λ+c→Σ0K+)=(3.58±0.19±0.06±0.19)×10−4. The first uncertainties are statistical and the second systematic, while the third uncertainties come from the uncertainties on the world average branching fractions of Λ+c→(Λ,Σ0)π+.

Study of B0-bar -> D+ h- (h = K/pi) decays at Belle

2022 · ARTICLE · en

We present a measurement of the branching fractions of the Cabibbo favored B0 → D+π- and the Cabibbo suppressed B0 → D+K- decays. We find Br(B0 → D+π-)=(2.48±0.01±0.09±0.04)×10-3 and Br(B0 → D+K−)=(2.03±0.05±0.07±0.03)×10-4 decays, where the first uncertainty is statistical, the second is systematic, and the third uncertainty is due to the D+ → K-π+π+ branching fraction. The ratio of branching fractions of B0→D+K- and B0→D+π- is measured to be RD=[8.19±0.20(stat)±0.23(syst)]×10-2. These measurements are performed using the full Belle dataset, which corresponds to 772×106 BB pairs and use the Belle II software framework for data analysis.

Search for the decay B0s→η′K0S

2022 · ARTICLE · en

We report the results of the first search for the decay B0s→η′K0S using 121.4 fb−1 of data collected at the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We observe no signal and set a 90% confidence-level upper limit of 8.16×10−6 on the B0s→η′K0S branching fraction.

Measurement of the branching fractions of the B+→ηℓ+νℓ and B+→η′ℓ+νℓ decays with signal-side only reconstruction in the full q2 range

2022 · ARTICLE · en

Search for Z′→μ+μ− in the Lμ−Lτ gauge-symmetric model at Belle

2022 · ARTICLE · en

Study of γγ→γψ(2S) at Belle

2022 · ARTICLE · en

Search for charged lepton flavor violating decays of Υ(1S)

2022 · ARTICLE · en