Constraints on the photon polarisation in b → sγ transitions using $$ {B}_s^0 $$ → ϕe+e− decays



Aaij, R, Abdelmotteleb, ASW, Abellan Beteta, C, Abudinén, F, Ackernley, T, Adefisoye, AA, Adeva, B, Adinolfi, M, Adlarson, P, Agapopoulou, C
et al (show 1131 more authors) (2025) Constraints on the photon polarisation in b → sγ transitions using $$ {B}_s^0 $$ → ϕe+e− decays. Journal of High Energy Physics, 2025 (3). 47-. ISSN 1126-6708, 1029-8479

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Abstract

<jats:title>A<jats:sc>bstract</jats:sc> </jats:title> <jats:p>An angular analysis of the <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ {B}_s^0 $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>B</mml:mi> <mml:mi>s</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math> </jats:alternatives> </jats:inline-formula> <jats:italic>→ ϕe</jats:italic> <jats:sup>+</jats:sup> <jats:italic>e</jats:italic> <jats:sup> <jats:italic>−</jats:italic> </jats:sup> decay is performed using the proton-proton collision dataset collected between 2011 and 2018 by the LHCb experiment, corresponding to an integrated luminosity of 9 fb<jats:sup> <jats:italic>−</jats:italic>1</jats:sup> at centre-of-mass energies of 7, 8 and 13 TeV. The analysis is performed in the very low dielectron invariant mass-squared region between 0<jats:italic>.</jats:italic>0009 and 0<jats:italic>.</jats:italic>2615 GeV<jats:sup>2</jats:sup> <jats:italic>/c</jats:italic> <jats:sup>4</jats:sup>. The longitudinal polarisation fraction of the <jats:italic>ϕ</jats:italic> meson is measured to be less than 11.5% at 90% confidence level. The <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ {A}_{\textrm{T}}^{\mathcal{R} eCP} $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>A</mml:mi> <mml:mi>T</mml:mi> <mml:mrow> <mml:mi>R</mml:mi> <mml:mi>eCP</mml:mi> </mml:mrow> </mml:msubsup> </mml:math> </jats:alternatives> </jats:inline-formula> observable, which is related to the lepton forward-backward asymmetry, is measured to be 0<jats:italic>.</jats:italic>116 <jats:italic>±</jats:italic> 0<jats:italic>.</jats:italic>155 <jats:italic>±</jats:italic> 0<jats:italic>.</jats:italic>006, where the first uncertainty is statistical and the second systematic. The transverse asymmetries, <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ {A}_{\textrm{T}}^{(2)} $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>A</mml:mi> <mml:mi>T</mml:mi> <mml:mfenced> <mml:mn>2</mml:mn> </mml:mfenced> </mml:msubsup> </mml:math> </jats:alternatives> </jats:inline-formula> and <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ {A}_{\textrm{T}}^{\mathcal{I} mCP} $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>A</mml:mi> <mml:mi>T</mml:mi> <mml:mrow> <mml:mi>I</mml:mi> <mml:mi>mCP</mml:mi> </mml:mrow> </mml:msubsup> </mml:math> </jats:alternatives> </jats:inline-formula>, which are sensitive to the virtual photon polarisation, are found to be <jats:italic>−</jats:italic>0<jats:italic>.</jats:italic>045 <jats:italic>±</jats:italic> 0<jats:italic>.</jats:italic>235 <jats:italic>±</jats:italic> 0<jats:italic>.</jats:italic>014 and 0<jats:italic>.</jats:italic>002 <jats:italic>±</jats:italic> 0<jats:italic>.</jats:italic>247 <jats:italic>±</jats:italic> 0<jats:italic>.</jats:italic>016, respectively. The results are consistent with Standard Model predictions.</jats:p>

Item Type: Article
Uncontrolled Keywords: 5106 Nuclear and Plasma Physics, 5107 Particle and High Energy Physics, 4902 Mathematical Physics, 49 Mathematical Sciences, 51 Physical Sciences
Divisions: Faculty of Science and Engineering
Faculty of Science and Engineering > School of Engineering
Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 05 Jun 2025 07:14
Last Modified: 05 Jun 2025 07:14
DOI: 10.1007/jhep03(2025)047
Open Access URL: https://link.springer.com/content/pdf/10.1007/JHEP...
Related Websites:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3193081