Semileptonic b-->u decays: lepton invariant mass spectrum

Area of Science:

• Particle Physics
• Quantum Chromodynamics
• Weak Interactions

Background:

• Precise determination of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |Vub| is crucial for understanding flavor physics.
• Lepton invariant mass spectrum in b decays provides a key observable for |Vub| determination.
• Higher-order corrections are necessary to reduce theoretical uncertainties.

Purpose of the Study:

• To compute the O(alpha(2)(s)) quantum chromodynamics (QCD) corrections to the lepton invariant mass spectrum in the decay b --> u l nu(l).
• To enable the evaluation of moments of the lepton energy distribution with O(alpha(2)(s)) accuracy.
• To provide corrections for muon decay and lifetime calculations.

Main Methods:

• Calculation of higher-order QCD corrections using perturbative methods.
• Analysis of the lepton invariant mass spectrum in b --> u l nu(l) decays.
• Integration of results to obtain moments of the lepton energy distribution and corrections to muon decay.

Main Results:

• The O(alpha(2)(s)) QCD corrections to the lepton invariant mass spectrum in b --> u l nu(l) decays have been computed.
• The methodology allows for O(alpha(2)(s)) accuracy in evaluating moments of the lepton energy distribution.
• The Abelian part of the result yields the neutrino invariant mass spectrum in muon decay and O(alpha(2)) correction to the muon lifetime.

Conclusions:

• The computed corrections enhance the precision of |Vub| determination from b decays.
• The developed method offers a versatile tool for precision calculations in particle physics.
• This work contributes to a more accurate understanding of weak decays and fundamental parameters.