cern.ch

First experimental study of photon polarization in radiative $B^{0}_{s}$ decays

[to restricted-access page]

Information

Tools

Abstract

The polarization of photons produced in radiative $B^{0}_{s}$ decays is studied for the first time. The data are recorded by the LHCb experiment in $pp$ collisions corresponding to an integrated luminosity of 3fb$^{-1}$ at center-of-mass energies of $7$ and $8$TeV. A time-dependent analysis of the $B^{0}_{s} \to \phi \gamma$ decay rate is conducted to determine the parameter ${\mathcal{A}}^\Delta$, which is related to the ratio of right- over left-handed photon polarization amplitudes in $b \to s \gamma$ transitions. A value of ${\mathcal{A}}^\Delta=-0.98^{ +0.46 +0.23}_{ -0.52 -0.20}$ is measured. This result is consistent with the Standard Model prediction within two standard deviations.

Figures and captions

Fits to the invariant mass distributions of the $ B ^0$ (top) and $ B ^0_ s $ (bottom) candidates.

 Fig1a.pdf [32 KiB]
HiDef png [526 KiB]
Thumbnail [324 KiB]
*.C file
Fig1a.pdf
Fig1b.pdf [30 KiB]
HiDef png [617 KiB]
Thumbnail [346 KiB]
*.C file
Fig1b.pdf

Background-subtracted decay-time distributions for $ B ^0 \rightarrow K ^{*0} \gamma $ (top) and $ B ^0_ s \rightarrow \phi \gamma $ (bottom) decays with the fit projections overlaid and normalized residuals shown below. The projections of a fit with $ {\mathcal{A}}^\Delta$ fixed to the central value of the SM prediction [2] are also shown. For display purposes, the PDF is shown as a histogram, integrated across each decay-time interval.

 Fig2a.pdf [18 KiB]
HiDef png [161 KiB]
Thumbnail [150 KiB]
*.C file
Fig2a.pdf
Fig2b.pdf [18 KiB]
HiDef png [168 KiB]
Thumbnail [156 KiB]
*.C file
Fig2b.pdf

Decay-time dependence of the ratio of the yields of $ B ^0_ s \rightarrow \phi \gamma $ and $ B ^0 \rightarrow K ^{*0} \gamma $ , with the fit overlaid. The expected distribution for the central value of the SM prediction [2] is also shown.

 Fig3.pdf [15 KiB]
HiDef png [134 KiB]
Thumbnail [132 KiB]
*.C file
Fig3.pdf

Animated gif made out of all figures.

 PAPER-2016-034.gif
Thumbnail
thumbnail_PAPER-2016-034.gif

Supplementary Material [file]

Supplementary material full pdf

 supple[..].pdf [141 KiB]
 supplementary.pdf

This ZIP file contains supplemetary material for the publication LHCb-PAPER-2016-034. The files are: Supplementary.pdf : An overview of the extra figures *.pdf, *.png, *.eps, *.C : The figures in variuous formats

Fig4a.pdf [31 KiB]
HiDef png [218 KiB]
Thumbnail [191 KiB]
*C file
Fig4a.pdf
Fig4b.pdf [31 KiB]
HiDef png [218 KiB]
Thumbnail [193 KiB]
*C file
Fig4b.pdf

Created on 27 April 2024.