First Observation of the Radiative Decay Λ_{b}^{0}→Λγ

Area of Science:

• High Energy Physics
• Particle Physics
• Experimental Physics

Background:

• Radiative decays of beauty hadrons are crucial for testing the Standard Model.
• Previous studies have focused on beauty mesons, leaving beauty baryon radiative decays largely unexplored.
• Understanding these decays can reveal new physics beyond the Standard Model.

Purpose of the Study:

• To report the first observation of the Λ_{b}^{0}→Λγ radiative decay.
• To measure the branching fraction of this rare decay process.
• To provide crucial data for theoretical models of heavy quark decays.

Main Methods:

• Analysis of proton-proton collision data collected by the LHCb experiment at 13 TeV.
• Utilizing a data sample corresponding to an integrated luminosity of 1.7 fb^{-1}.
• Employing the B^{0}→K^{*0}γ decay as a normalization mode for precise branching fraction measurement.

Main Results:

• The radiative decay Λ_{b}^{0}→Λγ was observed for the first time.
• The branching fraction was measured to be B(Λ_{b}^{0}→Λγ)=(7.1±1.5±0.6±0.7)×10^{-6}.
• This marks the first observation of a radiative decay involving a beauty baryon.

Conclusions:

• The observation of Λ_{b}^{0}→Λγ opens a new window into the study of heavy quark decays.
• The measured branching fraction provides a stringent test for theoretical predictions.
• This discovery contributes significantly to our understanding of fundamental particle interactions.