Abstract
Due to the heavy-quark symmetry of Non-Relativistic Quantum Chromodynamics (NRQCD), the cross-section for the production of ηc can be predicted. This NRQCD prediction when confronted with data from the LHCb is seen to fail miserably. We address this LHCb ηc anomaly in this paper using a new approach called modified NRQCD, an approach that has been shown to work extremely well for studying J/ψ, ψ′ and χc production at the LHC. We show, in the present paper, that the predictions for ηc production agrees very well with LHCb measurements at the three different values of energy that the experiment has presented data for. Modified NRQCD also explains the intriguing agreement of the LHCb ηc data with the colour-singlet prediction. The remarkable agreement of the theoretical predictions with the LHCb data suggests that modified NRQCD is closer to apprehending the true dynamics of quarkonium production.
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G.T. Bodwin, E. Braaten and G.P. Lepage, Rigorous QCD analysis of inclusive annihilation and production of heavy quarkonium, Phys. Rev. D 51 (1995) 1125 [Erratum ibid. 55 (1997) 5853] [hep-ph/9407339] [INSPIRE].
CDF collaboration, J/ψ and ψ(2S) production in \( p\overline{p} \) collisions at \( \sqrt{s} \) = 1.8 TeV, Phys. Rev. Lett. 79 (1997) 572 [INSPIRE].
CDF collaboration, Production of J/ψ mesons from χc meson decays in \( p\overline{p} \) collisions at \( \sqrt{s} \) = 1.8 TeV, Phys. Rev. Lett. 79 (1997) 578 [INSPIRE].
R. Baier and R. Ruckl, Hadronic collisions: a quarkonium factory, Z. Phys. C 19 (1983) 251 [INSPIRE].
M. Cacciari and M. Krämer, Color octet contributions to J/ψ photoproduction, Phys. Rev. Lett. 76 (1996) 4128 [hep-ph/9601276] [INSPIRE].
J. Amundson, S. Fleming and I. Maksymyk, Photoproduction of J/ψ in the forward region, Phys. Rev. D 56 (1997) 5844 [hep-ph/9601298] [INSPIRE].
S. Gupta and K. Sridhar, Color octet contributions to J/ψ hadroproduction at fixed target energies, Phys. Rev. D 54 (1996) 5545 [hep-ph/9601349] [INSPIRE].
S. Gupta and K. Sridhar, Color octet contributions to xF distributions in J/ψ hadroproduction at fixed target energies, Phys. Rev. D 55 (1997) 2650 [hep-ph/9608433] [INSPIRE].
M. Beneke and I.Z. Rothstein, Hadroproduction of quarkonia in fixed target experiments, Phys. Rev. D 54 (1996) 2005 [Erratum ibid. 54 (1996) 7082] [hep-ph/9603400] [INSPIRE].
W.-K. Tang and M. Vanttinen, Color octet J/ψ production at low pT, Phys. Rev. D 54 (1996) 4349 [hep-ph/9603266] [INSPIRE].
E. Braaten and Y.-Q. Chen, Signature for color octet production of J/ψ in e+e− annihilation, Phys. Rev. Lett. 76 (1996) 730 [hep-ph/9508373] [INSPIRE].
K.-M. Cheung, W.-Y. Keung and T.C. Yuan, Color octet quarkonium production at the Z pole, Phys. Rev. Lett. 76 (1996) 877 [hep-ph/9509308] [INSPIRE].
P.L. Cho, Prompt upsilon and psi production at LEP, Phys. Lett. B 368 (1996) 171 [hep-ph/9509355] [INSPIRE].
K.-M. Cheung, W.-Y. Keung and T.C. Yuan, Color octet J/ψ production in the υ decay, Phys. Rev. D 54 (1996) 929 [hep-ph/9602423] [INSPIRE].
P. Ko, J. Lee and H.S. Song, Inclusive S wave charmonium productions in B decays, Phys. Rev. D 53 (1996) 1409 [hep-ph/9510202] [INSPIRE].
G.T. Bodwin, E. Braaten, T.C. Yuan and G.P. Lepage, P wave charmonium production in B meson decays, Phys. Rev. D 46 (1992) R3703 [hep-ph/9208254] [INSPIRE].
K. Sridhar, A.D. Martin and W.J. Stirling, J/ψ production at the Tevatron and HERA: the effect of kT smearing, Phys. Lett. B 438 (1998) 211 [hep-ph/9806253] [INSPIRE].
P.L. Cho and M.B. Wise, Spin symmetry predictions for heavy quarkonia alignment, Phys. Lett. B 346 (1995) 129 [hep-ph/9411303] [INSPIRE].
M. Beneke and M. Krämer, Direct J/ψ and ψ′ polarization and cross-sections at the Tevatron, Phys. Rev. D 55 (1997) 5269 [hep-ph/9611218] [INSPIRE].
CDF collaboration, Measurement of J/ψ and ψ(2S) polarization in \( p\overline{p} \) collisions at \( \sqrt{s} \) = 1.8 TeV, Phys. Rev. Lett. 85 (2000) 2886 [hep-ex/0004027] [INSPIRE].
CDF collaboration, Polarization of J/ψ and ψ2S mesons produced in \( p\overline{p} \) collisions at \( \sqrt{s} \) = 1.96 TeV, Phys. Rev. Lett. 99 (2007) 132001 [arXiv:0704.0638] [INSPIRE].
P. Mathews, P. Poulose and K. Sridhar, ηc production at the Tevatron: a test of NRQCD, Phys. Lett. B 438 (1998) 336 [hep-ph/9803424] [INSPIRE].
K. Sridhar, Lhc, Phys. Lett. B 674 (2009) 36 [arXiv:0812.0474] [INSPIRE].
E. Braaten, B.A. Kniehl and J. Lee, Polarization of prompt J/ψ at the Tevatron, Phys. Rev. D 62 (2000) 094005 [hep-ph/9911436] [INSPIRE].
S.S. Biswal and K. Sridhar, etac production at the Large Hadron Collider, J. Phys. G 39 (2012) 015008 [arXiv:1007.5163] [INSPIRE].
K. Sridhar, P wave singlet charmonium production at the Tevatron, Phys. Rev. Lett. 77 (1996) 4880 [hep-ph/9609285] [INSPIRE].
LHCb collaboration, Measurement of the ηc(1S) production cross-section in proton-proton collisions via the decay ηc(1S) → \( p\overline{p} \), Eur. Phys. J. C 75 (2015) 311 [arXiv:1409.3612] [INSPIRE].
LHCb collaboration, Measurement of the ηc(1S) production cross-section in pp collisions at \( \sqrt{s} \) = 13 TeV, Eur. Phys. J. C 80 (2020) 191 [arXiv:1911.03326] [INSPIRE].
S.S. Biswal, S.S. Mishra and K. Sridhar, Understanding J/ψ and ψ′ production using a modified version of non-relativistic quantum chromodynamics, Phys. Lett. B 832 (2022) 137221 [arXiv:2201.09393] [INSPIRE].
S.S. Biswal, S.S. Mishra and K. Sridhar, χc production in modified NRQCD, Phys. Lett. B 834 (2022) 137490 [arXiv:2206.15252] [INSPIRE].
P.L. Cho and A.K. Leibovich, Color octet quarkonia production. 2, Phys. Rev. D 53 (1996) 6203 [hep-ph/9511315] [INSPIRE].
R. Gastmans, W. Troost and T.T. Wu, Production of heavy quarkonia from gluons, Nucl. Phys. B 291 (1987) 731 [INSPIRE].
Acknowledgments
One of us (K.S.) is grateful to members of the LHCb collaboration — Monica Pepe-Altarelli, Sergey Barsuk, Valeriia Zhovkovska and Andrii Usachov for valuable discussions. Discussions with Vaia Papadimitriou are also gratefully acknowledged.
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Biswal, S.S., Mishra, S.S. & Sridhar, K. Resolution of the LHCb ηc anomaly. J. High Energ. Phys. 2023, 120 (2023). https://doi.org/10.1007/JHEP05(2023)120
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DOI: https://doi.org/10.1007/JHEP05(2023)120