Measurement of the photon polarization in Λ<sub><i>b</i></sub><SUP>0</SUP> → Λγ decays

Aaij, R, Abdelmotteleb, ASW, Beteta, C Abellan, Abudinen, F, Ackernley, T, Adeva, B, Adinolfi, M, Afsharnia, H, Agapopoulou, C, Aidala, CA
et al (show 998 more authors) (2022) Measurement of the photon polarization in Λ<sub><i>b</i></sub><SUP>0</SUP> → Λγ decays. PHYSICAL REVIEW D, 105 (5). L051104-.

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The photon polarization in $b \to s \gamma$ transitions is measured for the first time in radiative b-baryon decays exploiting the unique spin structure of $\Lambda_b \to \Lambda \gamma$ decays. A data sample corresponding to an integrated luminosity of $6\;fb^{-1}$ collected by the LHCb experiment in $pp$ collisions at a center-of-mass energy of $13\;TeV$ is used. The photon polarization is measured to be $\alpha_{\gamma}= 0.82^{\,+\,0.17\,+\,0.04}_{\,-\,0.26\,-\,0.13}$, where the first uncertainty is statistical and the second systematic. This result is in agreement with the Standard Model prediction and previous measurements in b-meson decays. Charge-parity breaking effects are studied for the first time in this observable and found to be consistent with $CP$ symmetry.

Item Type: Article
Additional Information: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at (LHCb public pages)
Uncontrolled Keywords: hep-ex, hep-ex
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 16 May 2022 13:51
Last Modified: 14 Mar 2024 22:50
DOI: 10.1103/PhysRevD.105.L051104
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