First measurement of the forward rapidity dependence of W boson transverse helicity fractions

@misc{aaij2026first,
  title = {{First measurement of the forward rapidity dependence of $W$ boson transverse helicity fractions}},
  author = {R Aaij and M Abdelfatah and A.S.W Abdelmotteleb and C Abellan Beteta and F Abudinén and T Ackernley and A.A Adefisoye and B Adeva and M Adinolfi and P Adlarson and C Agapopoulou and C.A Aidala and S Akar and K Akiba and H Al Saleh and P Albicocco and J Albrecht and R Aleksiejunas and F Alessio and P Alvarez Cartelle and Jr A.A Alves and S Amato and J.L Amey and Y Amhis and Z Amos and L An and L Anderlini and P Andreola and M Andreotti and S. Andres Estrada and A Anelli and D Ao and C Arata and F Archilli and Z Areg and M Argenton and S. Arguedas Cuendis and L Arnone and M Artuso and E Aslanides and R. Ataíde da Silva and M Atzeni and B Audurier and J.A Authier and D Bacher and I Bachiller Perea and S Bachmann and M Bachmayer and J.J Back and M Bai and Z.B Bai and V Balagura and A Balboni and W Baldini and Z Baldwin and L Balzani and H Bao and J. Baptista de Souza Leite and C Barbero Pretel and I.R Barbosa},
  howpublished = {HAL},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.22555},
  eprint = {2609.22555},
  archivePrefix = {arXiv},
  url = {https://hal.science/hal-05763701v1},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - First measurement of the forward rapidity dependence of W boson transverse helicity fractions
AU  - R Aaij
AU  - M Abdelfatah
AU  - A.S.W Abdelmotteleb
AU  - C Abellan Beteta
AU  - F Abudinén
AU  - T Ackernley
AU  - A.A Adefisoye
AU  - B Adeva
AU  - M Adinolfi
AU  - P Adlarson
AU  - C Agapopoulou
AU  - C.A Aidala
AU  - S Akar
AU  - K Akiba
AU  - H Al Saleh
AU  - P Albicocco
AU  - J Albrecht
AU  - R Aleksiejunas
AU  - F Alessio
AU  - P Alvarez Cartelle
AU  - Jr A.A Alves
AU  - S Amato
AU  - J.L Amey
AU  - Y Amhis
AU  - Z Amos
AU  - L An
AU  - L Anderlini
AU  - P Andreola
AU  - M Andreotti
AU  - S. Andres Estrada
AU  - A Anelli
AU  - D Ao
AU  - C Arata
AU  - F Archilli
AU  - Z Areg
AU  - M Argenton
AU  - S. Arguedas Cuendis
AU  - L Arnone
AU  - M Artuso
AU  - E Aslanides
AU  - R. Ataíde da Silva
AU  - M Atzeni
AU  - B Audurier
AU  - J.A Authier
AU  - D Bacher
AU  - I Bachiller Perea
AU  - S Bachmann
AU  - M Bachmayer
AU  - J.J Back
AU  - M Bai
AU  - Z.B Bai
AU  - V Balagura
AU  - A Balboni
AU  - W Baldini
AU  - Z Baldwin
AU  - L Balzani
AU  - H Bao
AU  - J. Baptista de Souza Leite
AU  - C Barbero Pretel
AU  - I.R Barbosa
PY  - 2026
DA  - 2026/09/23
PB  - HAL
DO  - 10.48550/arxiv.2609.22555
UR  - https://hal.science/hal-05763701v1
AB  - The transverse helicity fractions of W bosons are measured as a function of the W boson rapidity, y_W, in the range 0 ≤ y_W ≤ 5 using W→μν_μ decays in pp collisions at √s = 13 TeV recorded by the LHCb experiment and corresponding to an integrated luminosity of $5.1$ fb^−1. The fractions are extracted from a template fit to the muon transverse momentum and pseudorapidity. The results show a strong rapidity dependence and agree with next-to-leading-order Standard Model predictions, providing the first determination of the transverse helicity fractions of W bosons in the forward region.
ER  -