Sneha Malde

Abstract:

Using a sample of (448.1±2.9)×106 ψ(3686) events collected with the BESIII detector, we perform the first partial wave analysis of ψ(3686)→K+K-η. In addition to the well established states, φ(1020), φ(1680), and K3∗(1780), contributions from X(1750), ρ(2150), ρ3(2250), and K2∗(1980) are also observed. The X(1750) state is determined to be a 1-resonance. The simultaneous observation of the φ(1680) and X(1750) indicates that the X(1750), with previous observations in photoproduction, is distinct from the φ(1680). The masses, widths, branching fractions of ψ(3686)→K+K-η, and the intermediate resonances are also measured.

Abstract:

We report four narrow peaks in the Ξ_{b}^{0}K^{-} mass spectrum obtained using pp collisions at center-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9  fb^{-1} recorded by the LHCb experiment. Referring to these states by their mass, the mass values are m[Ω_{b}(6316)^{-}]=6315.64±0.31±0.07±0.50  MeV, m[Ω_{b}(6330)^{-}]=6330.30±0.28±0.07±0.50  MeV, m[Ω_{b}(6340)^{-}]=6339.71±0.26±0.05±0.50  MeV, m[Ω_{b}(6350)^{-}]=6349.88±0.35±0.05±0.50  MeV, where the uncertainties are statistical, systematic, and the last is due to the knowledge of the Ξ_{b}^{0} mass. The natural widths of the three lower mass states are consistent with zero, and the 90% confidence-level upper limits are determined to be Γ[Ω_{b}(6316)^{-}]<2.8  MeV, Γ[Ω_{b}(6330)^{-}]<3.1  MeV and Γ[Ω_{b}(6340)^{-}]<1.5  MeV. The natural width of the Ω_{b}(6350)^{-} peak is 1.4_{-0.8}^{+1.0}±0.1  MeV, which is 2.5σ from zero and corresponds to an upper limit of 2.8 MeV. The peaks have local significances ranging from 3.6σ to 7.2σ. After accounting for the look-elsewhere effect, the significances of the Ω_{b}(6316)^{-} and Ω_{b}(6330)^{-} peaks are reduced to 2.1σ and 2.6σ, respectively, while the two higher mass peaks exceed 5σ. The observed peaks are consistent with expectations for excited Ω_{b}^{-} resonances.

Abstract:

A four-body amplitude analysis of the B− → D*+π−π− decay is performed, where fractions and relative phases of the various resonances contributing to the decay are measured. Several quasi-model-independent analyses are performed aimed at searching for the presence of new states and establishing the quantum numbers of previously observed charmed meson resonances. In particular the resonance parameters and quantum numbers are determined for the D1(2420), D1(2430), D0(2550), D∗1(2600), D2(2740) and D∗3(2750) states. The mixing between the D1(2420) and D1(2430) resonances is studied and the mixing parameters are measured. The dataset corresponds to an integrated luminosity of 4.7fb−1, collected in proton-proton collisions at center-of-mass energies of 7, 8 and 13 TeV with the LHCb detector.

Abstract:

Using a 2.93     fb − 1 data sample of electron-positron collisions taken with the BESIII detector at a center-of-mass energy of 3.773 GeV, which corresponds to ( 8296 ± 31 ± 64 ) × 10 3 D + D − pairs, we search for the baryon and lepton number violating decays D + → ¯ Λ ( ¯ Σ 0 ) e + and D + → Λ ( Σ 0 ) e + . No obvious signals are found with the current statistics and upper limits on the branching fractions of these four decays are set at the level of 10 − 6 at 90% confidence level.