Thomas D. Cohen

Functional integrals for QCD at nonzero chemical potential and zero density.

In a Euclidean space functional integral treatment of the free energy of QCD, a chemical potential enters only through the functional determinant of the Dirac operator which for any flavor is /D+m-mu(f)gamma(0) (where mu(f) is the chemical potential for the given flavor). Any nonzero mu alters all of the eigenvalues of the Dirac operator relative to the mu=0 value, leading to a naive expectation that the determinant is altered and which thereby alters the free energy. Phenomenologically, this does not occur at T=0 for sufficiently small mu, in contradiction to this naive expectation. The problem of how to understand this phenomenological behavior in terms of functional integrals is solved for the case of an isospin chemical through the study of the spectrum of the operator gamma(0)(/D+m). The case of the baryon chemical potential is briefly discussed.

Low-energy theorems for nucleon-nucleon scattering

Low energy theorems are derived for the coefficients of the effective range expansion in s-wave nucleon-nucleon scattering valid to leading order in an expansion in which both

pp-->pp pi 0 reaction near threshold: A chiral power counting approach.

m_\pi

Nonperturbative regularization and renormalization: Simple examples from nonrelativistic quantum mechanics

and

How short is too short? Constraining zero-range interactions in nucleon-nucleon scattering

1/a

Chiral multiplets versus parity doublets in highly excited baryons

(where

Is There a “Most Perfect Fluid” Consistent with Quantum Field Theory?

a

DOES ONE OBSERVE CHIRAL SYMMETRY RESTORATION IN BARYON SPECTRUM

is the scattering length) are treated as small mass scales. Comparisons with phase shift data, however, reveal a pattern of gross violations of the theorems for all coefficients in both the

Chiral condensate in holographic models of QCD

^1S_0

The Schwinger mechanism and graphene

and