Branching fraction measurements of η and η^′(958) anomalous decays

@misc{aaij2026branching,
  title = {{Branching fraction measurements of $η$ and $η^\prime(958)$ anomalous decays}},
  author = {Roel Aaij and Ahmed Sameh Wagih Abdelmotteleb and Carlos Abellan Beteta and Fernando Jesus Abudinén and Thomas Ackernley and Ayomide Matthew Adefisoye and Bernardo Adeva and Marco Adinolfi and Patrik Harri Adlarson and Christina Agapopoulou and Christine Angela Aidala and Ziad Ajaltouni and Simon Akar and Kazuyoshi Akiba and Pietro Albicocco and Johannes Albrecht and Ramunas Aleksiejunas and Federico Alessio and Paula Alvarez Cartelle and Renaud Amalric and Sandra Amato and Jake Lewis Amey and Yasmine Amhis and Liupan An and Lucio Anderlini and Martin Andersson and Pasquale Andreola and Mirco Andreotti and Sergio Andres Estrada and Alessia Anelli and Dong Ao and Carolina Arata and Flavio Archilli and Zaratsyan Areg and Matteo Argenton and Sergio Arguedas Cuendis and Lisa Arnone and Alexander Artamonov and Marina Artuso and Elie Aslanides and Rita Ataíde da Silva and Michele Atzeni and Benjamin Audurier and Juliette Authier and David Bacher and Irene Bachiller Perea and Sebastian Bachmann and Marie Bachmayer and John Back and Pablo Baladron Rodriguez and Vladislav Balagura and Anna Balboni and Wander Baldini and Zachary Baldwin and Luca Balzani and Haoran Bao and Juan Baptista de Souza Leite and Carlos Javier Barbero Pretel and Matteo Barbetti and Ivanildo Rui Barbosa},
  howpublished = {HAL},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.02973},
  eprint = {2609.02973},
  archivePrefix = {arXiv},
  url = {https://hal.science/hal-05759118v1},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Branching fraction measurements of η and η^′(958) anomalous decays
AU  - Roel Aaij
AU  - Ahmed Sameh Wagih Abdelmotteleb
AU  - Carlos Abellan Beteta
AU  - Fernando Jesus Abudinén
AU  - Thomas Ackernley
AU  - Ayomide Matthew Adefisoye
AU  - Bernardo Adeva
AU  - Marco Adinolfi
AU  - Patrik Harri Adlarson
AU  - Christina Agapopoulou
AU  - Christine Angela Aidala
AU  - Ziad Ajaltouni
AU  - Simon Akar
AU  - Kazuyoshi Akiba
AU  - Pietro Albicocco
AU  - Johannes Albrecht
AU  - Ramunas Aleksiejunas
AU  - Federico Alessio
AU  - Paula Alvarez Cartelle
AU  - Renaud Amalric
AU  - Sandra Amato
AU  - Jake Lewis Amey
AU  - Yasmine Amhis
AU  - Liupan An
AU  - Lucio Anderlini
AU  - Martin Andersson
AU  - Pasquale Andreola
AU  - Mirco Andreotti
AU  - Sergio Andres Estrada
AU  - Alessia Anelli
AU  - Dong Ao
AU  - Carolina Arata
AU  - Flavio Archilli
AU  - Zaratsyan Areg
AU  - Matteo Argenton
AU  - Sergio Arguedas Cuendis
AU  - Lisa Arnone
AU  - Alexander Artamonov
AU  - Marina Artuso
AU  - Elie Aslanides
AU  - Rita Ataíde da Silva
AU  - Michele Atzeni
AU  - Benjamin Audurier
AU  - Juliette Authier
AU  - David Bacher
AU  - Irene Bachiller Perea
AU  - Sebastian Bachmann
AU  - Marie Bachmayer
AU  - John Back
AU  - Pablo Baladron Rodriguez
AU  - Vladislav Balagura
AU  - Anna Balboni
AU  - Wander Baldini
AU  - Zachary Baldwin
AU  - Luca Balzani
AU  - Haoran Bao
AU  - Juan Baptista de Souza Leite
AU  - Carlos Javier Barbero Pretel
AU  - Matteo Barbetti
AU  - Ivanildo Rui Barbosa
PY  - 2026
DA  - 2026/09/04
PB  - HAL
DO  - 10.48550/arxiv.2609.02973
UR  - https://hal.science/hal-05759118v1
AB  - Branching fractions of η and η'(958) anomalous decays are measured using pp collision data at a center-of-mass energy of √s=13 TeV collected by the LHCb experiment and corresponding to an integrated luminosity of 5.4 fb^−1. The measured values and upper limits are calB(η→μ^+μ^-) &= (5.02±0.14±0.18±0.26)×10^−6 , calB(η'(958)→μ^+μ^-) &<1.9×10^−7 at 90% CL , calB(η→π^+π^-μ^+μ^-) &<5.4×10^−7 at 90% CL, calB(η'(958)→π^+π^-μ^+μ^-) &= (2.73±0.14±0.13±0.14)×10^−5 , where the uncertainties are, respectively, statistical, systematic, and due to the external branching fraction of the ϕ(1020)→μ^+μ^- decay, which is used for normalization. This marks the first experimental search for the η'(958) decay, and the most precise measurement of the branching fraction calB(η→μ^+μ^-) to date.
ER  -