Abstract
A search for the rare decay of a $B^{0}$ or $B^{0}_{s}$ meson into the final state $J/\psi\gamma$ is performed, using data collected by the LHCb experiment in $pp$ collisions at $\sqrt{s}=7$ and $8$ TeV, corresponding to an integrated luminosity of 3 fb$^{-1}$. The observed number of signal candidates is consistent with a background-only hypothesis. Branching fraction values larger than $1.7\times 10^{-6}$ for the $B^{0}\to J/\psi\gamma$ decay mode are excluded at 90% confidence level. For the $B^{0}_{s}\to J/\psi\gamma$ decay mode, branching fraction values larger than $7.4\times 10^{-6}$ are excluded at 90% confidence level, this is the first branching fraction limit for this decay.
Highlights
Decays of B mesons provide an interesting laboratory to study quantum chromodynamics (QCD)
A typical approach for predicting the branching fractions of such decays is to factorize the decay into a short-distance contribution which can be computed with perturbative QCD and a long-distance contribution for which nonperturbative QCD is required
Pseudoexperiments are generated in order to determine the observed and expected exclusion confidence level of the branching fraction value
Summary
Decays of B mesons provide an interesting laboratory to study quantum chromodynamics (QCD). Experimental measurements are crucial to test the different calculations of the QCD interactions within these decays, so helping to identify the most appropriate theoretical approaches for predicting observables. Theoretical predictions of the branching fractions of these decays vary significantly depending on the chosen approach for the treatment of QCD interactions in the decay dynamics. [1] the branching fraction, evaluated in the framework of QCD factorization [2], is expected to be ∼2 × 10−7, whereas the calculation in Ref. The relative efficiency between signal and normalization decay modes is calculated using simulated events. This efficiency is cross-checked using the decay B0 → KÃ0γ. VI, the upper limits on the branching fractions are calculated using the CLS method [5,6]
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