Observation of new resonances in the Λb0π+π- system

Research output: Contribution to journalArticlepeer-review

Authors

  • LHCb Collaboration

Colleges, School and Institutes

External organisations

  • Nikhef National Institute for Subatomic Physics
  • University of Zurich
  • University of Liverpool
  • Universidad de Santiago de Compostela
  • University of Bristol
  • LPC
  • Syracuse University
  • University of Michigan
  • Istituto Nazionale di Fisica Nucleare, Sezione di Milano
  • University of Cincinnati
  • Laboratori Nazionali dell'Infn di Frascati
  • TU Dortmund University, Germany
  • CERN
  • University of Glasgow
  • Universitat de Barcelona
  • Petersburg Nuclear Physics Institute (PNPI)
  • Imperial College London
  • Universidade Federal Do Rio de Janeiro
  • IN2P3
  • Sezione INFN di Firenze
  • Ecole Polytechnique Federale de Lausanne
  • Sezione INFN di Ferrara
  • Ruprecht-Karls-Universität Heidelberg
  • Institute for High Energy Physics (IHEP)
  • Yandex School of Data Analysis
  • INFN Sezione di Cagliari
  • University of Warwick
  • Institute of Physics

Abstract

We report the observation of a new structure in the Λb0π+π- spectrum using the full LHCb data set of pp collisions, corresponding to an integrated luminosity of 9 fb-1, collected at √s=7, 8, and 13 TeV. A study of the structure suggests its interpretation as a superposition of two almost degenerate narrow states. The masses and widths of these states are measured to be:
mΛb(6146)0=6146.17±0.33±0.22±0.16 MeV,
mΛb(6152)0=6152.51±0.26±0.22±0.16 MeV,
ΓΛb(6146)0=2.9±1.3±0.3 MeV,
ΓΛb(6152)0=2.1±0.8±0.3 MeV,
with a mass splitting of Δm=6.34±0.32±0.02 MeV, where the first uncertainty is statistical, the second systematic. The third uncertainty for the mass measurements derives from the knowledge of the mass of the Λb0 baryon. The measured masses and widths of these new excited states suggest their possible interpretation as a doublet of Λb(1D)0 states.

Details

Original languageEnglish
Article number152001
Number of pages11
JournalPhysical Review Letters
Volume123
Issue number15
Publication statusPublished - 11 Oct 2019

ASJC Scopus subject areas