Observation of the helicity-selection-rule suppressed decay of the χc2 charmonium state

(BESIII Collaboration)

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3 Scopus citations

Abstract

The decays of χc2→K+K-π0, KSK±π, and π+π-π0 are studied with the ψ(3686) data samples collected with the Beijing Spectrometer (BESIII). For the first time, the branching fractions of χc2→K∗K̄, χc2→a2±(1320)π/a20(1320)π0, and χc2→ρ(770)±π are measured. Here, K∗K̄ denotes both K∗±K and its isospin-conjugated process K∗0K̄0+c.c., and K∗ denotes the resonances K∗(892), K2∗(1430), and K3∗(1780). The observations indicate a strong violation of the helicity selection rule in χc2 decays into vector and pseudoscalar meson pairs. The measured branching fractions of χc2→K∗(892)K̄ are more than ten times larger than the upper limit of χc2→ρ(770)±π, which is so far the first direct observation of a significant U-spin symmetry breaking effect in charmonium decays.

Original languageEnglish (US)
Article number111102
JournalPhysical Review D
Volume96
Issue number11
DOIs
StatePublished - Dec 7 2017

Bibliographical note

Funding Information:
The BESIII Collaboration thanks the staff of BEPCII and the IHEP computing center for their strong support. This work is supported in part by National Key Basic Research Program of China under Contract No. 2015CB856700; National Natural Science Foundation of China (NSFC) under Contracts Nos. 11175188, 11375205, 11425525, 11565006, 11521505, 11735014, 11235011, 11322544, 11335008, 11425524, and 11635010; the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; the CAS Center for Excellence in Particle Physics (CCEPP); the Collaborative Innovation Center for Particles and Interactions (CICPI); Joint Large-Scale Scientific Facility Funds of the NSFC and CAS under Contracts Nos. U1232201 and U1332201; CAS under Contracts Nos. KJCX2-YW-N29 and KJCX2-YW-N45; 100 Talents Program of CAS; National 1000 Talents Program of China; INPAC and Shanghai Key Laboratory for Particle Physics and Cosmology; German Research Foundation DFG under Collaborative Research Center Contracts No. CRC 1044 and FOR 2359; Istituto Nazionale di Fisica Nucleare, Italy; Joint Large-Scale Scientific Facility Funds of the NSFC and CAS under Contract No. U1532257; Joint Large-Scale Scientific Facility Funds of the NSFC and CAS under Contract No. U1532258; Koninklijke Nederlandse Akademie van Wetenschappen (KNAW) under Contract No. 530-4CDP03; Ministry of Development of Turkey under Contract No. DPT2006K-120470; National Natural Science Foundation of China (NSFC) under Contracts No. 11575133 and No. 11275266; The Swedish Resarch Council; U.S. Department of Energy under Contracts Nos. DE-FG02-05ER41374, DE-SC-0010504, and DE-SC0012069; U.S. National Science Foundation; University of Groningen (RuG) and the Helmholtzzentrum fuer Schwerionenforschung GmbH (GSI), Darmstadt; and WCU Program of National Research Foundation of Korea under Contract No. R32-2008-000-10155-0.

Publisher Copyright:
© 2017 American Physical Society.

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