Semileptonic BsB_s decay measurements at LHCb

I discuss the first semileptonic $B_s$ decay measurements performed at LHCb, and the prospects for precise studies of $B_s$ semileptonic decay properties. The analyses covered here are based on data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV. In particular the semileptonic decays \Bs\to D_s^+ X \munu and \Bs\to D^0K^+ X \munu are studied. Two structures are observed in the $D^0K^+$ mass spectrum at masses consistent with the known $D_{s1}(2536)^+$ and $D^*_{s2}(2573)^{+}$ mesons. The measured branching fractions relative to the total \Bs semileptonic rate are {{\cal{B}}(\Bs\to D_{s2}^{*+} X \munu)}/{{\cal{B}}(\Bs\to X \munu)}= (3.3\pm 1.0\pm 0.4)%, and {{\cal{B}}(\Bs\to D_{s1}^+ X \munu)}/{{\cal{B}}(\Bs\to X \munu)}= (5.4\pm 1.2({\rm stat})\pm 0.5({\rm sys}))%. This is the first observation of the $D_{s2}^{*+}$ state in \Bs decays.Comment: Proceedings of CKM2010, the 6th International Workshop on the CKM Unitarity Triangle, University of Warwick, UK, 6-10 September 201

Inclusive B→XclνB \to X_c l \nu decay spectra at Belle and the determination of ∣Vcb∣|V_{cb}|

We report measurements of the inclusive electron energy spectrum and hadron invariant mass spectrum for charmed semileptonic decays of B mesons in a 140 fb^-1 data sample collected with the Belle detector at the KEKB e+e- collider. We determine the first four central moments and partial branching fraction of the electron energy spectrum for electron energy thresholds from 0.4 to 2.0 GeV, and the first two central and second non-central moments of the hadron invariant mass spectrum for lepton energy thresholds from 0.7 to 1.9 GeV. Using these measurements and Belle measurements of the photon energy moments in B -> X_s gamma decays, we determine the CKM matrix element |Vcb|, the b quark mass and higher order non-perturbative parameters that appear in the Heavy Quark Expansion by performing a global fit analysis in the kinetic mass and 1S schemes.Comment: 4 pages, 4 figures, Contribution to the Proceedings of the XXXIII International Conference of High Energy Physics (ICHEP'06), Moscow, 200

Belle II observation prospects for axion-like particle production from BB meson annihilation decay

We investigate a new production mechanism of axion-like particle (ALP) from $B$ meson annihilation decays and its observation potential at the Belle and Belle II experiments. This mechanism allows for the production of ALP from $B$ meson decays in association with a large variety of mesons. In this article, we first estimate the branching ratios of such processes with a perturbative QCD method. Focussing on the most promising $B \to h a^{\prime}$ ($h=K^\pm, \pi^\pm, D^0$ and $D_s$) channels, we perform sensitivity studies for $a^{\prime}$ decaying invisibly or into diphoton with Belle and Belle II experiments

The Full Event Interpretation -- An exclusive tagging algorithm for the Belle II experiment

The Full Event Interpretation is presented: a new exclusive tagging algorithm used by the high-energy physics experiment Belle II. The experimental setup of Belle II allows the precise measurement of otherwise inaccessible $B$ meson decay-modes. The Full Event Interpretation algorithm enables many of these measurements. The algorithm relies on machine learning to automatically identify plausible $B$ meson decay chains based on the data recorded by the detector. Compared to similar algorithms employed by previous experiments, the Full Event Interpretation provides a greater efficiency, yielding a larger effective sample size usable in the measurement.Comment: 11 pages, 7 figures, 1 tabl

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements