Using an amplitude analysis to measure the photon polarisation in $B \rightarrow K\pi \pi \gamma $ decays - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Eur.Phys.J.C Année : 2019

Using an amplitude analysis to measure the photon polarisation in $B \rightarrow K\pi \pi \gamma $ decays

V. Bellée
  • Fonction : Auteur
P. Pais
  • Fonction : Auteur
A. Puig Navarro
  • Fonction : Auteur
F. Blanc
  • Fonction : Auteur
O. Schneider
  • Fonction : Auteur
K. Trabelsi

Résumé

A method is proposed to measure the photon polarisation parameter $\lambda _{\gamma }$ in ${{b}} \!\rightarrow {s} {\gamma } $ transitions using an amplitude analysis of $B\!\rightarrow K\pi \pi {\gamma } $ decays. Simplified models of the ${K} {\pi } {\pi } $ system are used to simulate ${{{B} ^+}} \!\rightarrow {{K} ^+} {{\pi } ^-} {{\pi } ^+} {\gamma } $ and ${{B} ^0} \!\rightarrow {{K} ^+} {{\pi } ^-} {{\pi } ^0} {\gamma } $ decays, validate the amplitude analysis method, and demonstrate the feasibility of a measurement of the $\lambda _{\gamma }$ parameter irrespective of the model parameters. Similar sensitivities to $\lambda _{\gamma }$ are obtained with both the charged and neutral hadronic systems. In the absence of any background and distortion due to experimental effects, the statistical uncertainty expected from an analysis of ${{{B} ^+}} \!\rightarrow {{K} ^+} {{\pi } ^-} {{\pi } ^+} {\gamma } $ decays in an LHCb data set corresponding to an integrated luminosity of 9 $\,\hbox {fb}^{-1}$ is estimated to be 0.009. A similar measurement using ${{B} ^0} \!\rightarrow {{K} ^+} {{\pi } ^-} {{\pi } ^0} {\gamma } $ decays in a Belle II data sample corresponding to an integrated luminosity of 5 $\hbox {\,ab}^{-1}$ would lead to a statistical uncertainty of 0.018.

Dates et versions

hal-02066908 , version 1 (13-03-2019)

Identifiants

Citer

V. Bellée, P. Pais, A. Puig Navarro, F. Blanc, O. Schneider, et al.. Using an amplitude analysis to measure the photon polarisation in $B \rightarrow K\pi \pi \gamma $ decays. Eur.Phys.J.C, 2019, 79 (7), pp.622. ⟨10.1140/epjc/s10052-019-7127-3⟩. ⟨hal-02066908⟩
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