- Featured in Physics
- Editors' Suggestion
- Open Access
- Access by Xinjiang University
Comprehensive Analysis of the Decay
Phys. Rev. Lett. 137, 021802 – Published 8 July, 2026
DOI: https://doi.org/10.1103/24g9-yn9d
Abstract
An analysis of the decay is presented using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of . The full set of -averaged and -asymmetric angular observables is determined in bins of the invariant mass squared of the dimuon system, as well as the branching fraction relative to the decay. For the first time, the full set of observables pertaining to the S-wave contribution to the final state are presented and consideration is given to effects arising from the mass of the muons. The extracted -asymmetry observables show no significant deviations from zero. The measurements of the -averaged observables and the branching fractions continue to exhibit the pattern of tensions with the standard model predictions that have been seen in previous analyses that use part of the dataset considered in this Letter.
Physics Subject Headings (PhySH)
Viewpoint
A Widening Anomaly Strains the Standard Model
Does a new measurement of a rare decay of the neutral B meson portend new physics?
See more in Physics
Article Text
References (96)
- R. Aaij et al. (LHCb Collaboration), Angular analysis of the decay using of integrated luminosity, J. High Energy Phys. 02 (2016) 104.
- R. Aaij et al. (LHCb Collaboration), Measurements of the S-wave fraction in decays and the differential branching fraction, J. High Energy Phys. 11 (2016) 047; 04 (2017) 142(E).
- S. Wehle et al. (Belle Collaboration), Lepton-flavor-dependent angular analysis of , Phys. Rev. Lett. 118, 111801 (2017).
- M. Aaboud et al. (ATLAS Collaboration), Angular analysis of decays in collisions at with the ATLAS detector, J. High Energy Phys. 10 (2018) 047.
- R. Aaij et al. (LHCb Collaboration), Measurement of -averaged observables in the decay, Phys. Rev. Lett. 125, 011802 (2020).
- A. Hayrapetyan et al. (CMS Collaboration), Angular analysis of the decay in proton-proton collisions at , Phys. Lett. B 864, 139406 (2025).
- R. Aaij et al. (LHCb Collaboration), Differential branching fractions and isospin asymmetries of decays, J. High Energy Phys. 06 (2014) 133.
- R. Aaij et al. (LHCb Collaboration), Angular analysis of the decay, Phys. Rev. Lett. 126, 161802 (2021).
- R. Aaij et al. (LHCb Collaboration), Branching fraction measurements of the rare and decays, Phys. Rev. Lett. 127, 151801 (2021).
- R. Aaij et al. (LHCb Collaboration), Angular analysis of the rare decay , J. High Energy Phys. 11 (2021) 043.
- S. Descotes-Genon, J. Matias, and J. Virto, Understanding the anomaly, Phys. Rev. D 88, 074002 (2013).
- F. Beaujean, C. Bobeth, and D. van Dyk, Comprehensive Bayesian analysis of rare (semi)leptonic and radiative decays, Eur. Phys. J. C 74, 2897 (2014); 74, 3179(E) (2014).
- W. Altmannshofer and D. M. Straub, New physics in transitions after LHC run 1, Eur. Phys. J. C 75, 382 (2015).
- B. Capdevila, A. Crivellin, S. Descotes-Genon, J. Matias, and J. Virto, Patterns of new physics in transitions in the light of recent data, J. High Energy Phys. 01 (2018) 093.
- D. London and J. Matias, flavour anomalies: 2021 Theoretical status report, Annu. Rev. Nucl. Part. Sci. 72, 37 (2022).
- N. Gubernari, M. Reboud, D. van Dyk, and J. Virto, Improved theory predictions and global analysis of exclusive processes, J. High Energy Phys. 09 (2022) 133.
- A. Greljo, J. Salko, A. Smolkovič, and P. Stangl, Rare decays meet high-mass Drell-Yan, J. High Energy Phys. 05 (2023) 087.
- M. Ciuchini, M. Fedele, E. Franco, A. Paul, L. Silvestrini, and Mauro Valli, Constraints on lepton universality violation from rare decays, Phys. Rev. D 107, 055036 (2023).
- M. Algueró, A. Biswas, B. Capdevila, S. Descotes-Genon, J. Matias, and M. Novoa-Brunet, To (b)e or not to (b)e: No electrons at LHCb, Eur. Phys. J. C 83, 648 (2023).
- A. Khodjamirian, T. Mannel, A. A. Pivovarov, and Y.-M. Wang, Charm-loop effect in and , J. High Energy Phys. 09 (2010) 089.
- A. Khodjamirian, T. Mannel, and Y.-M. Wang, decay at large hadronic recoil, J. High Energy Phys. 02 (2013) 010.
- C. Bouchard et al. (HPQCD Collaboration), Rare decay form factors from lattice QCD, Phys. Rev. D 88, 054509 (2013); 88, 079901(E) (2013).
- R. R. Horgan, Z. Liu, S. Meinel, and M. Wingate, Lattice QCD calculation of form factors describing the rare decays and , Phys. Rev. D 89, 094501 (2014).
- J. Lyon and R. Zwicky, Resonances gone topsy turvy—The charm of QCD or new physics in ?, arXiv:1406.0566.
- R. R. Horgan, Z. Liu, S. Meinel, and M. Wingate, Rare decays using lattice QCD form factors, Proc. Sci. LATTICE2014 (2015) 372.
- J. A. Bailey et al., decay form factors from three-flavor lattice QCD, Phys. Rev. D 93, 025026 (2016).
- A. Bharucha, D. M. Straub, and R. Zwicky, in the standard model from light-cone sum rules, J. High Energy Phys. 08 (2016) 098.
- A. Agadjanov, V. Bernard, U.-G. Meißner, and A. Rusetsky, The form factors on the lattice, Nucl. Phys. B910, 387 (2016).
- A. Khodjamirian and A. V. Rusov, and decays at large recoil and CKM matrix elements, J. High Energy Phys. 08 (2017) 112.
- C. Bobeth, M. Chrzaszcz, D. van Dyk, and J. Virto, Long-distance effects in from analyticity, Eur. Phys. J. C 78, 451 (2018).
- N. Gubernari, A. Kokulu, and D. van Dyk, and form factors from -meson light-cone sum sules beyond leading twist, J. High Energy Phys. 01 (2019) 150.
- S. Descotes-Genon, A. Khodjamirian, and J. Virto, Light-cone sum rules for form factors and applications to rare decays, J. High Energy Phys. 12 (2019) 083.
- J. Gao, C.-D. Lü, Y.-L. Shen, Y.-M. Wang, and Y.-B. Wei, Precision calculations of form factors from soft-collinear effective theory sum rules on the light-cone, Phys. Rev. D 101, 074035 (2020).
- N. Gubernari, D. van Dyk, and J. Virto, Non-local matrix elements in , J. High Energy Phys. 02 (2021) 088.
- N. Gubernari, M. Reboud, D. van Dyk, and J. Virto, Dispersive analysis of and form factors, J. High Energy Phys. 12 (2023) 153; 01 (2025) 125(E).
- S. Descotes-Genon, A. Khodjamirian, J. Virto, and K. K. Vos, Light-cone sum rules for -wave form factors, J. High Energy Phys. 06 (2023) 034.
- W. G. Parrott, C. Bouchard, and C. T. H. Davies (HPQCD Collaboration), Standard model predictions for , and using form factors from lattice QCD, Phys. Rev. D 107, 014511 (2023); 107, 119903(E) (2023).
- A. Y. Korchin and V. A. Kovalchuk, Contribution of vector resonances to the decay, Eur. Phys. J. C 72, 2155 (2012).
- S. Jäger and J. Martin Camalich, On at small dilepton invariant mass, power corrections, and new physics, J. High Energy Phys. 05 (2013) 043.
- S. Jäger and J. Martin Camalich, Reassessing the discovery potential of the decays in the large-recoil region: SM challenges and BSM opportunities, Phys. Rev. D 93, 014028 (2016).
- M. Ciuchini, M. Fedele, E. Franco, S. Mishima, A. Paul, L. Silvestrini, and M. Valli, decays at large recoil in the Standard Model: A theoretical reappraisal, J. High Energy Phys. 06 (2016) 116.
- G. Isidori, Z. Polonsky, and A. Tinari, Explicit estimate of charm rescattering in , Phys. Rev. D 111, 093007 (2025).
- G. Isidori, Z. Polonsky, and A. Tinari, Charm rescattering in : An improved analysis, Eur. Phys. J. C 85, 1221 (2025).
- R. Aaij et al. (LHCb Collaboration), Amplitude analysis of the decay, Phys. Rev. Lett. 132, 131801 (2024).
- R. Aaij et al. (LHCb Collaboration), Comprehensive analysis of local and nonlocal amplitudes in the decay, J. High Energy Phys. 09 (2024) 026; 05 (2025) 208(E).
- R. Aaij et al. (LHCb Collaboration), Differential branching fraction and angular analysis of the decay , Phys. Rev. Lett. 108, 181806 (2012).
- R. Aaij et al. (LHCb Collaboration), Differential branching fraction and angular analysis of the decay , J. High Energy Phys. 08 (2013) 131.
- R. Aaij et al. (LHCb Collaboration), Measurement of form-factor-independent observables in the decay , Phys. Rev. Lett. 111, 191801 (2013).
- R. Aaij et al. (LHCb Collaboration), Measurement of asymmetries in the decays and , J. High Energy Phys. 09 (2014) 177.
- M. Algueró, P. A. Cartelle, A. Mclean Marshall, P. Masjuan, J. Matias, M. A. McCann, M. Patel, K. A. Petridis, and M. Smith, A complete description of P- and S-wave contributions to the decay, J. High Energy Phys. 12 (2021) 085.
- A. Ali, P. Ball, L. T. Handoko, and G. Hiller, Comparative study of the decays (, in standard model and supersymmetric theories, Phys. Rev. D 61, 074024 (2000).
- F. Krüger, L. M. Sehgal, N. Sinha, and R. Sinha, Angular distribution and asymmetries in the decays and , Phys. Rev. D 61, 114028 (2000); 63, 019901(E) (2000).
- F. Krüger and J. Matias, Probing new physics via the transverse amplitudes of at large recoil, Phys. Rev. D 71, 094009 (2005).
- W. Altmannshofer, P. Ball, A. Bharucha, A. J. Buras, D. M. Straub, and M. Wick, Symmetries and asymmetries of decays in the standard model and beyond, J. High Energy Phys. 01 (2009) 019.
- U. Egede, T. Hurth, J. Matias, M. Ramon, and W. Reece, New observables in the decay mode , J. High Energy Phys. 11 (2008) 032.
- D. Bečirević and E. Schneider, On transverse asymmetries in , Nucl. Phys. B854, 321 (2012).
- C. Bobeth, G. Hiller, and D. van Dyk, The benefits of decays at low recoil, J. High Energy Phys. 07 (2010) 098.
- U. Egede, T. Hurth, J. Matias, M. Ramon, and W. Reece, On the new physics reach of the decay mode , J. High Energy Phys. 10 (2010) 056.
- C. Bobeth, G. Hiller, and D. van Dyk, More benefits of semileptonic rare decays at low recoil: violation, J. High Energy Phys. 07 (2011) 067.
- C. Bobeth, G. Hiller, and D. van Dyk, General analysis of decays at low recoil, Phys. Rev. D 87, 034016 (2013).
- J. Matias, F. Mescia, M. Ramon, and J. Virto, Complete anatomy of and its angular distribution, J. High Energy Phys. 04 (2012) 104.
- J. Matias, On the S-wave pollution of observables, Phys. Rev. D 86, 094024 (2012).
- C. Bobeth, G. Hiller, and G. Piranishvili, asymmetries in and untagged , decays at NLO, J. High Energy Phys. 07 (2008) 106.
- S. Descotes-Genon, J. Matias, M. Ramon, and J. Virto, Implications from clean observables for the binned analysis of at large recoil, J. High Energy Phys. 01 (2013) 048.
- G. Kumar and N. Mahajan, : Zeroes of angular observables as test of standard model, Phys. Rev. D 93, 054041 (2016).
- A. A. Alves, Jr. et al. (LHCb Collaboration), The LHCb detector at the LHC, J. Instrum. 3, S08005 (2008).
- R. Aaij et al. (LHCb Collaboration), LHCb detector performance, Int. J. Mod. Phys. A 30, 1530022 (2015).
- R. Aaij et al., The LHCb trigger and its performance in 2011, J. Instrum. 8, P04022 (2013).
- N. Grieser et al., The LHCb stripping project: Sustainable legacy data processing for high-energy physics, Comput. Software Big Sci. 9, 21 (2025).
- T. Sjöstrand, S. Mrenna, and P. Skands, A brief introduction to pythia 8.1, Comput. Phys. Commun. 178, 852 (2008).
- D. J. Lange, The evtgen particle decay simulation package, Nucl. Instrum. Methods Phys. Res., Sect. A 462, 152 (2001).
- J. Allison et al. (Geant4 Collaboration), geant4 developments and applications, IEEE Trans. Nucl. Sci. 53, 270 (2006); S. Agostinelli et al. (Geant4 Collaboration), geant4: A simulation toolkit, Nucl. Instrum. Methods Phys. Res., Sect. A 506, 250 (2003).
- L. Anderlini et al., The pidcalib package, Report No. LHCb-PUB-2016-021, CERN, 2016, http://cds.cern.ch/record/2202412.
- R. Aaij et al., Selection and processing of calibration samples to measure the particle identification performance of the LHCb experiment in Run 2, Eur. Phys. J. Tech. Instrum. 6, 1 (2019).
- R. Aaij et al. (LHCb Collaboration), Measurement of the track reconstruction efficiency at LHCb, J. Instrum. 10, P02007 (2015).
- L. Breiman, J. H. Friedman, R. A. Olshen, and C. J. Stone, Classification and Regression Trees (Wadsworth international group, Belmont, California, 1984).
- Y. Freund and R. E. Schapire, A decision-theoretic generalization of on-line learning and an application to boosting, J. Comput. Syst. Sci. 55, 119 (1997).
- M. Pivk and F. R. Le Diberder, sPlot: A statistical tool to unfold data distributions, Nucl. Instrum. Methods Phys. Res., Sect. A 555, 356 (2005).
- A. Blum, A. Kalai, and J. Langford, Beating the hold-out: Bounds for k-fold and progressive cross-validation, in Proceedings of the 12th Annual Conference on Computational Learning Theory, COLT ’99 (ACM, New York, 1999), p. 203, 10.1145/307400.307439.
- R. Aaij et al. (LHCb Collaboration), Search for the rare decays and , Phys. Lett. B 699, 330 (2011).
- S. Navas et al. (Particle Data Group), Review of particle physics, Phys. Rev. D 110, 030001 (2024).
- C. Weisser and M. Williams, Machine learning and multivariate goodness of fit, arXiv:1612.07186.
- K. Chilikin et al. (Belle Collaboration), Observation of a new charged charmoniumlike state in decays, Phys. Rev. D 90, 112009 (2014).
- R. Aaij et al. (LHCb Collaboration), Measurement of the polarization amplitudes in decays, Phys. Rev. D 88, 052002 (2013).
- J. M. Blatt and V. F. Weisskopf, Theoretical Nuclear Physics (Springer, New York, 1952).
- D. Aston et al., A study of scattering in the reaction at , Nucl. Phys. B296, 493 (1988).
- Z. Rui and W.-F. Wang, -wave contributions to the hadronic charmonium decays in the perturbative QCD approach, Phys. Rev. D 97, 033006 (2018).
- R. Aaij et al. (LHCb Collaboration), Observation of the resonant character of the state, Phys. Rev. Lett. 112, 222002 (2014).
- K. Chilikin et al. (Belle Collaboration), Experimental constraints on the spin and parity of the , Phys. Rev. D 88, 074026 (2013).
- T. Skwarnicki, A study of the radiative cascade transitions between the Upsilon-prime and Upsilon resonances, Ph.D. thesis, Institute of Nuclear Physics, Krakow, 1986; Report No. DESY-F31-86-02.
- J. Neyman, Outline of a theory of statistical estimation based on the classical theory of probability, Phil. Trans. R. Soc. A 236, 333 (1937).
- LHCb Collaboration, HEPData record for: Comprehensive analysis of the decay, HEPData (2026), 10.17182/hepdata.167733.
- M. Williams, How good are your fits? Unbinned multivariate goodness-of-fit tests in high energy physics, J. Instrum. 5, P09004 (2010).
- D. M. Straub, flavio: A Python package for flavour and precision phenomenology in the Standard Model and beyond, arXiv:1810.08132.
- D. van Dyk et al. (EOS Authors Collaboration), eos: A software for flavor physics phenomenology, Eur. Phys. J. C 82, 569 (2022).
- N. Gubernari, M. Reboud, D. van Dyk, and J. Virto, Improved theory predictions and global analysis of exclusive processes, J. High Energy Phys. 09 (2022) 133.