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Observation of the J/$ψ$ $\to$ $μ^+μ^-μ^+μ^-$ decay in proton-proton collisions at $\sqrt{s}$ = 13 TeV (2403.11352v2)

Published 17 Mar 2024 in hep-ex

Abstract: The J/$\psi$ $\to$ $\mu+\mu-\mu+\mu-$ decay has been observed with a statistical significance in excess of five standard deviations. The analysis is based on an event sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of 33.6 fb${-1}$. Normalizing to the J/$\psi$ $\to$ $\mu+\mu-$ decay mode leads to a branching fraction [10.1 ${+3.3}_{-2.7}$ (stat) $\pm$ 0.4 (syst)] $\times$ 10${-7}$, a value that is consistent with the standard model prediction.

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References (28)
  1. CMS Collaboration, “The CMS experiment at the CERN LHC”, JINST 3 (2008) S08004, 10.1088/1748-0221/3/08/S08004.
  2. CMS Collaboration, “Development of the CMS detector for the CERN LHC Run 3”, 2023. arXiv:2309.05466. Accepted by JINST.
  3. CMS Collaboration, “Observation of \PZdecays to four leptons with the CMS detector at the LHC”, JHEP 12 (2012) 034, 10.1007/JHEP12(2012)034, arXiv:1210.3844.
  4. CMS Collaboration, “Observation of the Z→\uppsi⁢\Pell+⁢\Pell−→Z\uppsisuperscript\Pellsuperscript\Pell\mathrm{Z}\to\uppsi\Pell^{+}\Pell^{-}roman_Z → start_POSTSUPERSCRIPT + end_POSTSUPERSCRIPT start_POSTSUPERSCRIPT - end_POSTSUPERSCRIPT decay in pp collisions at s=13⁢\TeV𝑠13\TeV\sqrt{s}=13\TeVsquare-root start_ARG italic_s end_ARG = 13”, Phys. Rev. Lett. 121 (2018) 141801, 10.1103/PhysRevLett.121.141801, arXiv:1806.04213.
  5. CMS Collaboration, “Observation of the rare decay of the η𝜂\etaitalic_η meson to four muons”, Phys. Rev. Lett. 131 (2023) 091903, 10.1103/PhysRevLett.131.091903, arXiv:2305.04904.
  6. BES III Collaboration, “Observation of \JPsidecays to \Pep⁢\Pem⁢\Pep⁢\Pem\Pep\Pem\Pep\Pem\Pep\Pem\Pep\Pem and \Pep⁢\Pem⁢\PGmp⁢\PGmm\Pep\Pem\PGmp\PGmm\Pep\Pem\PGmp\PGmm”, 2021. arXiv:2111.13881. Submitted to Phys. Rev. Lett.
  7. M. Drees, M. Shi, and Z. Zhang, “Constraints on U⁢(1)Lμ−Lτ𝑈subscript1subscript𝐿𝜇subscript𝐿𝜏U(1)_{L_{\mu}-L_{\tau}}italic_U ( 1 ) start_POSTSUBSCRIPT italic_L start_POSTSUBSCRIPT italic_μ end_POSTSUBSCRIPT - italic_L start_POSTSUBSCRIPT italic_τ end_POSTSUBSCRIPT end_POSTSUBSCRIPT from LHC Data”, Phys. Lett. B 791 (2019) 130, 10.1016/j.physletb.2019.02.029, arXiv:1811.12446.
  8. K. Harigaya et al., “Muon g-2 and LHC phenomenology in the Lμ−Lτsubscript𝐿𝜇subscript𝐿𝜏L_{\mu}-L_{\tau}italic_L start_POSTSUBSCRIPT italic_μ end_POSTSUBSCRIPT - italic_L start_POSTSUBSCRIPT italic_τ end_POSTSUBSCRIPT gauge symmetric model”, JHEP 03 (2014) 105, 10.1007/JHEP03(2014)105, arXiv:1311.0870.
  9. N. F. Bell, Y. Cai, R. K. Leane, and A. D. Medina, “Leptophilic dark matter with \PZ′superscript\PZ′\PZ^{\prime}start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT interactions”, Phys. Rev. D 90 (2014) 035027, 10.1103/PhysRevD.90.035027, arXiv:1407.3001.
  10. W. Chen et al., “Four-lepton decays of neutral vector mesons”, Phys. Rev. D 104 (2021) 094023, 10.1103/PhysRevD.104.094023, arXiv:2009.12363.
  11. C. Gütschow and M. Schönherr, “Four lepton production and the accuracy of QED FSR”, Eur. Phys. J. C 81 (2021) 48, 10.1140/epjc/s10052-020-08816-9, arXiv:2007.15360.
  12. CMS Collaboration, “CMS luminosity measurement for the 2018 data-taking period at s=13⁢\TeV𝑠13\TeV\sqrt{s}=13\TeVsquare-root start_ARG italic_s end_ARG = 13”, CMS Physics Analysis Summary CMS-PAS-LUM-18-002, 2019.
  13. CMS Collaboration, “Performance of the CMS Level-1 trigger in proton-proton collisions at s=13𝑠13\sqrt{s}=13square-root start_ARG italic_s end_ARG = 13 TeV”, JINST 15 (2020) P10017, 10.1088/1748-0221/15/10/P10017, arXiv:2006.10165.
  14. CMS Collaboration, “The CMS trigger system”, JINST 12 (2017) P01020, 10.1088/1748-0221/12/01/P01020, arXiv:1609.02366.
  15. CMS Collaboration, “Performance of the CMS muon detector and muon reconstruction with proton-proton collisions at s=13𝑠13\sqrt{s}=13square-root start_ARG italic_s end_ARG = 13 TeV”, JINST 13 (2018) P06015, 10.1088/1748-0221/13/06/P06015, arXiv:1804.04528.
  16. CMS Collaboration, “Test of lepton flavor universality in B±plus-or-minus{}^{\pm}start_FLOATSUPERSCRIPT ± end_FLOATSUPERSCRIPT→→\to→ Kμ+±⁢μ−superscriptsuperscript𝜇plus-or-minussuperscript𝜇{}^{\pm}\mu^{+}\mu^{-}start_FLOATSUPERSCRIPT ± end_FLOATSUPERSCRIPT italic_μ start_POSTSUPERSCRIPT + end_POSTSUPERSCRIPT italic_μ start_POSTSUPERSCRIPT - end_POSTSUPERSCRIPT and B±plus-or-minus{}^{\pm}start_FLOATSUPERSCRIPT ± end_FLOATSUPERSCRIPT→→\to→ K±plus-or-minus{}^{\pm}start_FLOATSUPERSCRIPT ± end_FLOATSUPERSCRIPTe+{}^{+}start_FLOATSUPERSCRIPT + end_FLOATSUPERSCRIPTe−{}^{-}start_FLOATSUPERSCRIPT - end_FLOATSUPERSCRIPT decays in proton-proton collisions at s=13𝑠13\sqrt{s}=13square-root start_ARG italic_s end_ARG = 13\TeV”, 2024. arXiv:2401.07090. Submitted to Reports on Progress in Physics.
  17. CMS Collaboration, “Description and performance of track and primary-vertex reconstruction with the CMS tracker”, JINST 9 (2014) P10009, 10.1088/1748-0221/9/10/P10009, arXiv:1405.6569.
  18. T. Sjöstrand et al., “An introduction to PYTHIA 8.2”, Comput. Phys. Commun. 191 (2015) 159, 10.1016/j.cpc.2015.01.024, arXiv:1410.3012.
  19. D. J. Lange, “The EvtGen particle decay simulation package”, Nucl. Instrum. Meth. A 462 (2001) 152, 10.1016/S0168-9002(01)00089-4.
  20. CMS Collaboration, “Extraction and validation of a new set of CMS PYTHIA8 tunes from underlying-event measurements”, Eur. Phys. J. C 80 (2020) 4, 10.1140/epjc/s10052-019-7499-4, arXiv:1903.12179.
  21. NNPDF Collaboration, “Parton distributions from high-precision collider data”, Eur. Phys. J. C 77 (2017) 663, 10.1140/epjc/s10052-017-5199-5, arXiv:1706.00428.
  22. E. Barberio and Z. Wa̧s, “PHOTOS: A universal Monte Carlo for QED radiative corrections. Version 2.0”, Comput. Phys. Commun. 79 (1994) 291, 10.1016/0010-4655(94)90074-4.
  23. GEANT4 Collaboration, “\GEANTfour—a simulation toolkit”, Nucl. Instrum. Meth. A 506 (2003) 250, 10.1016/S0168-9002(03)01368-8.
  24. R. Frühwirth, “Application of Kalman filtering to track and vertex fitting”, Nucl. Instrum. Meth. A 262 (1987) 444, 10.1016/0168-9002(87)90887-4.
  25. M. J. Oreglia, “A study of the reactions ψ′→γ⁢γ⁢ψ→superscript𝜓′𝛾𝛾𝜓\psi^{\prime}\to\gamma\gamma\psiitalic_ψ start_POSTSUPERSCRIPT ′ end_POSTSUPERSCRIPT → italic_γ italic_γ italic_ψ”. PhD thesis, Stanford University, 1980. SLAC Report SLAC-R-236.
  26. Particle Data Group Collaboration, “Review of Particle Physics”, PTEP 2022 (2022) 083C01, 10.1093/ptep/ptac097.
  27. G. Cowan, K. Cranmer, E. Gross, and O. Vitells, “Asymptotic formulae for likelihood-based tests of new physics”, Eur. Phys. J. C 71 (2011) 1554, 10.1140/epjc/s10052-011-1554-0, arXiv:1007.1727. [Erratum: \DOI10.1140/epjc/s10052-013-2501-z].
  28. HEPData record for this analysis, 2024. 10.17182/hepdata.147273.

Summary

  • The paper presents the first observation of the J/ψ meson decaying into four muons with a significance above five standard deviations.
  • It measures the branching fraction as [10.1⁺³.³₋₂.₇(stat) ± 0.4(syst)]×10⁻⁷, which aligns closely with Standard Model expectations.
  • The study leverages CMS detector data from 13 TeV proton-proton collisions and employs advanced simulation tools to optimize signal reconstruction and background understanding.

Observation of Rare J/psi Decay in Proton-Proton Collisions

The paper in question elucidates the first observation of a particularly rare decay of the J/psi meson into four muons, with a detailed measurement of its branching fraction relative to the well-studied decay into two muons. Conducted using the CMS experiment data collected from proton-proton collisions at a center-of-mass energy of 13 TeV from the LHC in 2018, the analysis brings significant insight into standard model (SM) predictions and beyond.

Key Findings and Methodology

The decay under observation displays a statistical significance well above five standard deviations, indicating a clear event above the background noise. The CMS collaboration collected data amounting to an integrated luminosity of 33.6 fb⁻¹ and utilized this extensive dataset to probe potential four-lepton signatures. The branching fraction of the decay was measured as $[10.1^{+3.3}_{-2.7}\stat \pm 0.4\syst] \times 10^{-7}$, corresponding well with the SM expectation of (9.74±0.05)×10−7(9.74\pm 0.05)\times 10^{-7}. Such consistency underscores the robustness of SM predictions even in rare decay scenarios.

The CMS apparatus, featuring a powerful solenoidal magnet and multiple tracking and calorimetry layers, is optimized for deep investigations into such decay channels. Its extensive coverage and precise muon detection capabilities, achieving over 90% efficiency, are critical for the observed analysis. The analysis utilized a specialized "B Parking" data sample optimized for events rich in bottom (b) hadrons, which provided effective pathways to reconstructing instances of the decay signature.

Advanced simulations facilitated by the PYTHIA and EVTGEN Monte Carlo generators underpinned the measurement processes, finely tuned to accommodate for pileup and other collider-induced interactions. The choice of parton distribution functions (NNPDF 3.1) and dedicated photon radiation modeling through PHOTOS showcases the meticulous approach towards simulating and understanding event topologies.

Implications and Future Prospects

The observation of this decay mode, in line with SM predictions, offers a reaffirmation of the SM while providing a platform to explore nuances beyond it. Such rare decays act as potential sites for peering into new physics, transcending potential mediators like hypothetical gauge bosons emerging from various beyond-SM theories. Continued exploration in this domain could illuminate discrepancies hinting at new physics, should they exist within achievable experimental precision in future analyses.

The continuity and efficacy of similar investigations stand bolstered by the operational efficiency of the LHC and the CMS detector. As datasets grow and machine learning methodologies enhance data analysis precision, future observations may explore increasingly rare and elusive decay pathways.

In conclusion, the paper presents a comprehensive paper grounded firmly in the experimental and theoretical frameworks yet receptive to forthcoming advancements in collider physics and beyond.

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Authors (1)

  1. CMS Collaboration
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