Please use this identifier to cite or link to this item: https://hdl.handle.net/11147/8445
Title: Constraints on the chi(c1 )versus chi(c2) Polarizations in Proton-Proton Collisions at root s=8 TeV
Authors: Sirunyan, A. M.
Tumasyan, A.
Adam, W.
Ambrogi, F.
Bergauer, T.
Dragicevic, M.
Karapınar, Güler
CMS Collaboration
Issue Date: 2020
Publisher: American Physical Society
Abstract: The polarizations of promptly produced chi(c1) and chi(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at root s = 8 TeV. The chi(c) states are reconstructed via their radiative decays chi(c) -> J/psi gamma, with the photons being measured through conversions to e(+)e(-), which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the chi(c2) to chi(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/psi -> mu(+)mu(-) decay, in three bins of J/psi transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the hclicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum.
Description: WOS: 000528518000007
PubMed: 32383915
URI: https://doi.org/10.1103/PhysRevLett.124.162002
https://hdl.handle.net/11147/8445
ISSN: 0031-9007
1079-7114
Appears in Collections:PubMed İndeksli Yayınlar Koleksiyonu / PubMed Indexed Publications Collection
WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

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