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Coupled-channel interpretation of the LHCb double-$J/\psi$ spectrum and hints of a new state near the $J/\psi J/\psi$ threshold

Recently, the LHCb Collaboration reported pronounced structures in the invariant mass spectrum of J/ψ pairs produced in proton-proton collisions at the Large Hadron Collider. In this Letter, we argue that the data can be very well described within two variants of a coupled-channel approach employing...

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Autores principales: Dong, Xiang-Kun, Baru, Vadim, Guo, Feng-Kun, Hanhart, Christoph, Nefediev, Alexey
Lenguaje:eng
Publicado: 2020
Materias:
Acceso en línea:https://dx.doi.org/10.1103/PhysRevLett.126.132001
https://dx.doi.org/10.1103/PhysRevLett.127.119901
http://cds.cern.ch/record/2759264
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author Dong, Xiang-Kun
Baru, Vadim
Guo, Feng-Kun
Hanhart, Christoph
Nefediev, Alexey
author_facet Dong, Xiang-Kun
Baru, Vadim
Guo, Feng-Kun
Hanhart, Christoph
Nefediev, Alexey
author_sort Dong, Xiang-Kun
collection CERN
description Recently, the LHCb Collaboration reported pronounced structures in the invariant mass spectrum of J/ψ pairs produced in proton-proton collisions at the Large Hadron Collider. In this Letter, we argue that the data can be very well described within two variants of a coupled-channel approach employing T matrices consistent with unitarity: (i) with just two channels, J/ψJ/ψ and ψ(2S)J/ψ, as long as energy-dependent interactions in these channels are allowed, or (ii) with three channels J/ψJ/ψ, ψ(2S)J/ψ, and ψ(3770)J/ψ with just constant contact interactions. Both formulations hint at the existence of a near-threshold state in the J/ψJ/ψ system with the quantum numbers JPC=0++ or 2++, which we refer to as X(6200). We suggest experimental tests to check the existence of this state and discuss what additional channels need to be studied experimentally to allow for distinctive tests between the two mechanisms proposed. If the molecular nature of X(6200), as hinted by the three-channel approach, is confirmed, many other double-quarkonium states should exist driven by the same binding mechanism. In particular, there should be an ηcηc molecule with a similar binding energy.
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institution Organización Europea para la Investigación Nuclear
language eng
publishDate 2020
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spelling cern-27592642023-04-16T02:01:41Zdoi:10.1103/PhysRevLett.126.132001doi:10.1103/PhysRevLett.127.119901http://cds.cern.ch/record/2759264engDong, Xiang-KunBaru, VadimGuo, Feng-KunHanhart, ChristophNefediev, AlexeyCoupled-channel interpretation of the LHCb double-$J/\psi$ spectrum and hints of a new state near the $J/\psi J/\psi$ thresholdnucl-thNuclear Physics - Theoryhep-latParticle Physics - Latticehep-exParticle Physics - Experimenthep-phParticle Physics - PhenomenologyRecently, the LHCb Collaboration reported pronounced structures in the invariant mass spectrum of J/ψ pairs produced in proton-proton collisions at the Large Hadron Collider. In this Letter, we argue that the data can be very well described within two variants of a coupled-channel approach employing T matrices consistent with unitarity: (i) with just two channels, J/ψJ/ψ and ψ(2S)J/ψ, as long as energy-dependent interactions in these channels are allowed, or (ii) with three channels J/ψJ/ψ, ψ(2S)J/ψ, and ψ(3770)J/ψ with just constant contact interactions. Both formulations hint at the existence of a near-threshold state in the J/ψJ/ψ system with the quantum numbers JPC=0++ or 2++, which we refer to as X(6200). We suggest experimental tests to check the existence of this state and discuss what additional channels need to be studied experimentally to allow for distinctive tests between the two mechanisms proposed. If the molecular nature of X(6200), as hinted by the three-channel approach, is confirmed, many other double-quarkonium states should exist driven by the same binding mechanism. In particular, there should be an ηcηc molecule with a similar binding energy.Recently, the LHCb Collaboration reported pronounced structures in the invariant mass spectrum of $J/\psi$-pairs produced in proton-proton collisions at the Large Hadron Collider. In this Letter, we argue that the data can be very well described within two variants of a coupled-channel approach employing $T$-matrices consistent with unitarity: (i) with just two channels, $J/\psi J/\psi$ and $\psi(2S)J/\psi$, as long as energy-dependent interactions in these channels are allowed, or (ii) with three channels $J/\psi J/\psi$, $\psi(2S)J/\psi$ and $\psi(3770)J/\psi$ with just constant contact interactions. Both formulations hint at the existence of a near-threshold state in the $J/\psi J/\psi$ system with the quantum numbers $J^{PC}=0^{++}$ or $2^{++}$, which we refer to as $X(6200)$. We suggest experimental tests to check the existence of this state and discuss what additional channels need to be studied experimentally to allow for distinctive tests between the two mechanisms proposed. If the molecular nature of the $X(6200)$, as hinted by the three-channel approach, is confirmed, many other double-quarkonium states should exist driven by the same binding mechanism. In particular, there should be an $\eta_c\eta_c$ molecule with a similar binding energy.arXiv:2009.07795oai:cds.cern.ch:27592642020-09-16
spellingShingle nucl-th
Nuclear Physics - Theory
hep-lat
Particle Physics - Lattice
hep-ex
Particle Physics - Experiment
hep-ph
Particle Physics - Phenomenology
Dong, Xiang-Kun
Baru, Vadim
Guo, Feng-Kun
Hanhart, Christoph
Nefediev, Alexey
Coupled-channel interpretation of the LHCb double-$J/\psi$ spectrum and hints of a new state near the $J/\psi J/\psi$ threshold
title Coupled-channel interpretation of the LHCb double-$J/\psi$ spectrum and hints of a new state near the $J/\psi J/\psi$ threshold
title_full Coupled-channel interpretation of the LHCb double-$J/\psi$ spectrum and hints of a new state near the $J/\psi J/\psi$ threshold
title_fullStr Coupled-channel interpretation of the LHCb double-$J/\psi$ spectrum and hints of a new state near the $J/\psi J/\psi$ threshold
title_full_unstemmed Coupled-channel interpretation of the LHCb double-$J/\psi$ spectrum and hints of a new state near the $J/\psi J/\psi$ threshold
title_short Coupled-channel interpretation of the LHCb double-$J/\psi$ spectrum and hints of a new state near the $J/\psi J/\psi$ threshold
title_sort coupled-channel interpretation of the lhcb double-$j/\psi$ spectrum and hints of a new state near the $j/\psi j/\psi$ threshold
topic nucl-th
Nuclear Physics - Theory
hep-lat
Particle Physics - Lattice
hep-ex
Particle Physics - Experiment
hep-ph
Particle Physics - Phenomenology
url https://dx.doi.org/10.1103/PhysRevLett.126.132001
https://dx.doi.org/10.1103/PhysRevLett.127.119901
http://cds.cern.ch/record/2759264
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