Observation of new excited Bs0 states

LHCb collaboration

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Abstract

A structure is observed in the B +/- K -/+ mass spectrum in a sample of proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, collected with the LHCb detector and corresponding to a total integrated luminosity of 9<mml:mspace width="0.166667em"></mml:mspace>fb-1. The structure is interpreted as the result of overlapping excited Bs0</mml:msubsup> states. With high significance, a two-peak hypothesis provides a better description of the data than a single resonance. Under this hypothesis the masses and widths of the two states, assuming they decay directly to B +/- K -/+, are determined to be <disp-formula id="Equ2"><mml:mtable><mml:mtr><mml:mtd columnalign="right">m1</mml:mtd><mml:mtd columnalign="left">=6063.5 +/- 1.2<mml:mspace width="0.333333em"></mml:mspace>(stat)+/- 0.8<mml:mspace width="0.333333em"></mml:mspace>(syst)<mml:mspace width="0.166667em"></mml:mspace>Me<mml:mspace width="0.333333em"></mml:mspace>,</mml:mtd></mml:mtr><mml:mtr><mml:mtd columnalign="right">Gamma 1</mml:mtd><mml:mtd columnalign="left">=26 +/- 4<mml:mspace width="0.333333em"></mml:mspace>(stat)+/- 4<mml:mspace width="0.333333em"></mml:mspace>(syst)<mml:mspace width="0.166667em"></mml:mspace>Me<mml:mspace width="0.333333em"></mml:mspace>,</mml:mtd></mml:mtr><mml:mtr><mml:mtd columnalign="right">m2</mml:mtd><mml:mtd columnalign="left">=6114 +/- 3<mml:mspace width="0.333333em"></mml:mspace>(stat)+/- 5<mml:mspace width="0.333333em"></mml:mspace>(syst)<mml:mspace width="0.166667em"></mml:mspace>Me<mml:mspace width="0.333333em"></mml:mspace>,</mml:mtd></mml:mtr><mml:mtr><mml:mtd columnalign="right"><mml:msub>Gamma 2</mml:mtd><mml:mtd columnalign="left">=66 +/- 18<mml:mspace width="0.333333em"></mml:mspace>(stat)+/- 21<mml:mspace width="0.333333em"></mml:mspace>(syst)<mml:mspace width="0.166667em"></mml:mspace>Me<mml:mspace width="0.333333em"></mml:mspace>.</mml:mtd></mml:mtr></mml:mtable><graphic position="anchor" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="10052_2021_9305_Article_Equ2.gif"></graphic></disp-formula>Alternative values assuming a decay through B +/- K -/+, with a missing photon from the B +/- -> B +/- gamma decay, which are shifted by approximately 45<mml:mspace width="0.166667em"></mml:mspace>MeV, are also determined. The possibility of a single state decaying in both channels is also considered. The ratio of the total production cross-section times branching fraction of the new states relative to the previously observed Bs20 state is determined to be 0.87 +/- 0.15<mml:mspace width="0.333333em"></mml:mspace>(stat)+/- 0.19<mml:mspace width="0.333333em"></mml:mspace>(syst).
Original languageEnglish
Article number601
Number of pages11
JournalEuropean Physical Journal C
Volume81
Issue number7
DOIs
Publication statusPublished - 1 Jul 2021

Keywords

  • MODEL

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