Phenomenological analysis of heavy hadron lifetimes

Journal Article · Mon Sep 01 04:00:00 EDT 1997 · Physical Review, D

DOI:https://doi.org/10.1103/PhysRevD.56.2783· OSTI ID:538706

Cheng, H ^[1]

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1. Institute of Physics, Academia Sinica, Taipei, Taiwan 115, Republic of (China)

A phenomenological analysis of lifetimes of bottom and charmed hadrons within the framework of the heavy quark expansion is performed. The baryon matrix element is evaluated using the bag model and the nonrelativistic quark model. We find that bottom-baryon lifetimes follow the pattern {tau}({Omega}{sub b}){approx_equal}{tau}({Xi}{sub b}{sup {minus}}){gt}{tau}({Lambda}{sub b}){approx_equal}{tau}({Xi}{sub b}{sup 0}). However, neither the lifetime ratio {tau}({Lambda}{sub b})/{tau}(B{sub d}) nor the absolute decay rates of the {Lambda}{sub b} baryon and B mesons can be explained. One way of solving both difficulties is to allow the presence of linear 1/m{sub Q} corrections by scaling the inclusive nonleptonic width with the fifth power of the hadron mass m{sub H{sub Q}} rather than the heavy quark mass m{sub Q}. The hierarchy of bottom baryon lifetimes is dramatically modified to {tau}({Lambda}{sub b}){gt}{tau}({Xi}{sub b}{sup {minus}}){gt}{tau}({Xi}{sub b}{sup 0}){gt}{tau}({Omega}{sub b}): The longest-lived {Omega}{sub b} among bottom baryons in the OPE prescription now becomes the shortest lived. The replacement of m{sub Q} by m{sub H{sub Q}} in nonleptonic widths is natural and justified in the PQCD-based factorization approach formulated in terms of hadron-level kinematics. For inclusive charmed baryon decays, we argue that since the heavy quark expansion does not converge, local duality cannot be tested in this case. We show that while the ansatz of substituting the heavy quark mass by the hadron mass provides a much better description of the charmed-baryon lifetime {ital ratios}, it appears unnatural and unpredictive for describing the {ital absolute} inclusive decay rates of charmed baryons, contrary to the bottom case. {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 538706
• Journal Information: Physical Review, D, Journal Name: Physical Review, D Journal Issue: 5 Vol. 56; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
B MESONS
BAG MODEL
BEAUTY BARYONS
CHARM PARTICLES
CHARMED BARYONS
CHARMED MESONS
DUALITY
FACTORIZATION
LAMBDA B NEUTRAL BARYONS
LAMBDA BARYONS
LIFETIME
MASS
OPERATOR PRODUCT EXPANSION
PERTURBATION THEORY
QUANTUM CHROMODYNAMICS
QUARK MODEL
SCALING