Observation of structure in the J/ψ-pair mass spectrum

LHCb collaboration; S. Playfer

doi:10.1016/j.scib.2020.08.032

Observation of structure in the J/ψ-pair mass spectrum

LHCb collaboration
, S. Playfer

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

sing proton-proton collision data at centre-of-mass energies of √s=7,8 and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 9 fb-1, the invariant mass spectrum of J/ψ pairs is studied. A narrow structure around 6.9GeV/c2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed. The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6.2 and 7.4 GeV/c2, covering predicted masses of states composed of four charm quarks. The mass and natural width of the narrow X (6900) structure are measured assuming a Breit-Wigner lineshape.

Original language	English
Pages (from-to)	1983-1993
Number of pages	11
Journal	Science Bulletin
Volume	65
Issue number	23
DOIs	https://doi.org/10.1016/j.scib.2020.08.032
Publication status	Published - 15 Dec 2020

Keywords / Materials (for Non-textual outputs)

QCD
Exotics
Tetraquark
Spectroscopy
Quarkonium
Particle and resonance production

Access to Document

10.1016/j.scib.2020.08.032Licence: Creative Commons: Attribution (CC-BY)

http://arxiv.org/abs/2006.16957

Experimental Particle Physics at the University of Edinburgh
Leonidopoulos, C. (Principal Investigator)
1/04/23 → 30/09/25
Project: Research
Experimental Particle Physics at the University of Edinburgh
Leonidopoulos, C. (Principal Investigator)
1/10/22 → 30/09/25
Project: Research
Beautiful Flavours: Discovering New Physics with B-hadrons and Tau-leptons
Barter, W. (Principal Investigator)
1/07/22 → 30/06/26
Project: Research

Cite this

@article{728497d1ca1e46d29d7da7edb8b5eacd,

title = "Observation of structure in the J/ψ-pair mass spectrum",

abstract = "sing proton-proton collision data at centre-of-mass energies of √s=7,8 and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 9 fb-1, the invariant mass spectrum of J/ψ pairs is studied. A narrow structure around 6.9GeV/c2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed. The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6.2 and 7.4 GeV/c2, covering predicted masses of states composed of four charm quarks. The mass and natural width of the narrow X (6900) structure are measured assuming a Breit-Wigner lineshape.",

keywords = "QCD, Exotics, Tetraquark, Spectroscopy, Quarkonium, Particle and resonance production",

author = "\{LHCb collaboration\} and William Barter and P.E.L. Clarke and S. Gambetta and F. Muheim and M. Needham and Mark Williams and Federico Betti and Robert Currie and S. Eisenhardt and Lavra, \{Lais Soares\} and Gediminas Sarpis and S. Playfer",

year = "2020",

month = dec,

day = "15",

doi = "10.1016/j.scib.2020.08.032",

language = "English",

volume = "65",

pages = "1983--1993",

journal = "Science Bulletin",

issn = "2095-9273",

publisher = "Elsevier",

number = "23",

}

TY - JOUR

T1 - Observation of structure in the J/ψ-pair mass spectrum

AU - LHCb collaboration

AU - Barter, William

AU - Clarke, P.E.L.

AU - Gambetta, S.

AU - Muheim, F.

AU - Needham, M.

AU - Williams, Mark

AU - Betti, Federico

AU - Currie, Robert

AU - Eisenhardt, S.

AU - Lavra, Lais Soares

AU - Sarpis, Gediminas

AU - Playfer, S.

PY - 2020/12/15

Y1 - 2020/12/15

N2 - sing proton-proton collision data at centre-of-mass energies of √s=7,8 and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 9 fb-1, the invariant mass spectrum of J/ψ pairs is studied. A narrow structure around 6.9GeV/c2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed. The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6.2 and 7.4 GeV/c2, covering predicted masses of states composed of four charm quarks. The mass and natural width of the narrow X (6900) structure are measured assuming a Breit-Wigner lineshape.

AB - sing proton-proton collision data at centre-of-mass energies of √s=7,8 and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 9 fb-1, the invariant mass spectrum of J/ψ pairs is studied. A narrow structure around 6.9GeV/c2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed. The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6.2 and 7.4 GeV/c2, covering predicted masses of states composed of four charm quarks. The mass and natural width of the narrow X (6900) structure are measured assuming a Breit-Wigner lineshape.

KW - QCD

KW - Exotics

KW - Tetraquark

KW - Spectroscopy

KW - Quarkonium

KW - Particle and resonance production

U2 - 10.1016/j.scib.2020.08.032

DO - 10.1016/j.scib.2020.08.032

M3 - Article

SN - 2095-9273

VL - 65

SP - 1983

EP - 1993

JO - Science Bulletin

JF - Science Bulletin

IS - 23

ER -

Observation of structure in the J/ψ-pair mass spectrum

Abstract

Keywords / Materials (for Non-textual outputs)

Access to Document

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Projects

Experimental Particle Physics at the University of Edinburgh

Experimental Particle Physics at the University of Edinburgh

Beautiful Flavours: Discovering New Physics with B-hadrons and Tau-leptons

Cite this