[Paper Review] Heavy Quark Physics

Mark B. Wise|ArXiv.org|May 26, 1998

Quantum Chromodynamics and Particle Interactions4 citations

TL;DR

This paper presents a comprehensive review of Heavy Quark Effective Theory (HQET) and Non-Relativistic Quantum Chromodynamics (NRQCD), providing foundational frameworks for studying heavy quark systems in quantum chromodynamics. It outlines how these effective field theories simplify the dynamics of heavy quarks, enabling precise predictions for decay rates, form factors, and spectroscopic properties of heavy hadrons.

ABSTRACT

A review of Heavy Quark Effective Theory and Non Relativistic Quantum Chromondynamics is given. Some applications are discussed.

Motivation & Objective

• To provide a systematic introduction to Heavy Quark Effective Theory (HQET) and Non-Relativistic QCD (NRQCD) for phenomenological applications.
• To clarify the theoretical foundations of HQET and NRQCD in the context of heavy quark systems.
• To discuss key applications such as heavy quark decays, form factors, and hadronic spectroscopy.
• To serve as a pedagogical and reference resource for researchers attending the 1997 Les Houches Summer School.
• To establish a framework for precision calculations in heavy flavor physics using effective field theory techniques.

Proposed method

• Derives HQET as an effective field theory in the infinite quark mass limit, simplifying QCD dynamics for heavy quarks.
• Applies the heavy quark spin and flavor symmetry to classify hadronic states and constrain form factors.
• Uses NRQCD to describe bound states of heavy quarks via non-relativistic expansion in the strong coupling constant and velocity.
• Constructs the effective Lagrangian for HQET, including leading and higher-order corrections in inverse heavy quark mass.
• Integrates both frameworks to analyze inclusive and exclusive decays of heavy hadrons.
• Applies operator product expansion and factorization theorems to compute decay rates and distribution functions.

Experimental results

Research questions

• RQ1 How can HQET be systematically derived and applied to describe the weak decays of heavy hadrons?
• RQ2 What are the leading-order and higher-order corrections in the 1/m_Q expansion in HQET?
• RQ3 How does NRQCD provide a framework for computing the properties of quarkonia and other heavy quark bound states?
• RQ4 What are the implications of heavy quark spin and flavor symmetries for form factor relations and sum rules?
• RQ5 How can effective field theory techniques be used to achieve precision predictions in heavy flavor physics?

Key findings

• HQET provides a systematic expansion in inverse powers of the heavy quark mass, enabling model-independent predictions for form factors.
• Heavy quark symmetry leads to universal relations between form factors in B and B* decays, reducing theoretical uncertainty.
• NRQCD allows the factorization of short-distance and long-distance contributions in quarkonium production and decay processes.
• The effective theory framework enables the computation of inclusive decay rates with corrections up to order 1/m_Q^2.
• The combination of HQET and NRQCD provides a consistent theoretical basis for analyzing heavy flavor physics at B-factories and hadron colliders.
• The paper establishes a foundation for future precision tests of QCD and the Standard Model using heavy quark systems.