Despite the f0(980) hadron having been discovered half a century ago, the question about its quark content has not been settled: it might be an ordinary quark-antiquark (qq) meson, a tetraquark (qqqq) exotic state, a kaon-antikaon (KK) molecule, or a quark-antiquark-gluon (qqg) hybrid. This paper reports strong evidence that the f0(980) state is an ordinary qq meson, inferred from the scaling of elliptic anisotropies (v2) with the number of constituent quarks (nq), as empirically established using conventional hadrons in relativistic heavy ion collisions. The f0(980) state is reconstructed via its dominant decay channel f0(980) → π+ π− , in proton-lead collisions recorded by the CMS experiment at the LHC, and its v2 is measured as a function of transverse momentum (pT). It is found that the nq = 2 (qq state) hypothesis is favored over nq = 4 (qqqq or KK states) by 7.7, 6.3, or 3.1 standard deviations in the pT < 10, 8, or 6 GeV/c ranges, respectively, and over nq = 3 (qqg hybrid state) by 3.5 standard deviations in the pT < 8 GeV/c range. This result represents the first determination of the quark content of the f0(980) state, made possible by using a novel approach, and paves the way for similar studies of other exotic hadron candidates.

Null, N., Hayrapetyan, A., Tumasyan, A., Adam, W., Andrejkovic, J.W., Bergauer, T., et al. (2025). Elliptic anisotropy measurement of the f0(980) hadron in proton-lead collisions and evidence for its quark-antiquark composition. NATURE COMMUNICATIONS, 16(1), 1-19 [10.1038/s41467-025-56200-6].

Elliptic anisotropy measurement of the f0(980) hadron in proton-lead collisions and evidence for its quark-antiquark composition

Battilana, C.;Bonacorsi, D.;Borgonovi, L.;Castro, A.;Cuffiani, M.;Diotalevi, T.;Fanfani, A.;Giommi, L.;Guiducci, L.;Lunerti, L.;Rovelli, T.;Siroli, G. P.;
2025

Abstract

Despite the f0(980) hadron having been discovered half a century ago, the question about its quark content has not been settled: it might be an ordinary quark-antiquark (qq) meson, a tetraquark (qqqq) exotic state, a kaon-antikaon (KK) molecule, or a quark-antiquark-gluon (qqg) hybrid. This paper reports strong evidence that the f0(980) state is an ordinary qq meson, inferred from the scaling of elliptic anisotropies (v2) with the number of constituent quarks (nq), as empirically established using conventional hadrons in relativistic heavy ion collisions. The f0(980) state is reconstructed via its dominant decay channel f0(980) → π+ π− , in proton-lead collisions recorded by the CMS experiment at the LHC, and its v2 is measured as a function of transverse momentum (pT). It is found that the nq = 2 (qq state) hypothesis is favored over nq = 4 (qqqq or KK states) by 7.7, 6.3, or 3.1 standard deviations in the pT < 10, 8, or 6 GeV/c ranges, respectively, and over nq = 3 (qqg hybrid state) by 3.5 standard deviations in the pT < 8 GeV/c range. This result represents the first determination of the quark content of the f0(980) state, made possible by using a novel approach, and paves the way for similar studies of other exotic hadron candidates.
2025
Null, N., Hayrapetyan, A., Tumasyan, A., Adam, W., Andrejkovic, J.W., Bergauer, T., et al. (2025). Elliptic anisotropy measurement of the f0(980) hadron in proton-lead collisions and evidence for its quark-antiquark composition. NATURE COMMUNICATIONS, 16(1), 1-19 [10.1038/s41467-025-56200-6].
Null, Null; Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Hussain, P. S.; ...espandi
File in questo prodotto:
File Dimensione Formato  
_89_s41467-025-56200-6.pdf

accesso aperto

Tipo: Versione (PDF) editoriale / Version Of Record
Licenza: Licenza per Accesso Aperto. Creative Commons Attribuzione (CCBY)
Dimensione 44.88 MB
Formato Adobe PDF
44.88 MB Adobe PDF Visualizza/Apri
s41467-025-56200-6_compressed.pdf

accesso aperto

Tipo: Versione (PDF) editoriale / Version Of Record
Licenza: Licenza per Accesso Aperto. Creative Commons Attribuzione (CCBY)
Dimensione 2.81 MB
Formato Adobe PDF
2.81 MB Adobe PDF Visualizza/Apri
41467_2025_56200_MOESM1_ESM.pdf

accesso aperto

Descrizione: Transparent Peer Review file
Tipo: File Supplementare
Licenza: Licenza per Accesso Aperto. Creative Commons Attribuzione (CCBY)
Dimensione 952.4 kB
Formato Adobe PDF
952.4 kB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/1041746
Citazioni
  • ???jsp.display-item.citation.pmc??? 1
  • Scopus 0
  • ???jsp.display-item.citation.isi??? 3
  • OpenAlex ND
social impact