532 research outputs found
Heavy Hadrons and QCD Instantons
Heavy hadrons are analyzed in a random and dilute gas of instantons. We
derive the instanton-induced interactions between heavy and light quarks at
next to leading order in the heavy quark mass and in the planar approximation,
and discuss their effects on the hadronic spectrum. The role of these
interactions in the formation of exotic hadrons is also discussed.Comment: 26 pages, REVTeX, 2 tables, 5 figures, uses FEYNMAN.st
Improved AdS/QCD Model with Matter
We study an improved AdS/QCD model at finite temperature and chemical
potential. An Ansatz for the beta-function for the boundary theory allows for
the derivation of a charged dilatonic black hole in bulk. The solution is
asymptotically RN-AdS in the UV and AdS2 * R3 in the IR. We discuss the
thermodynamical aspects of the solution. The fermionic susceptibilities are
shown to deviate from the free fermionic limits at asymptotic temperatures
despite the asymptotically free nature of the gauge coupling at the boundary.
The Polyakov line, the temporal and spatial string tensions dependence on both
temperature and chemical potential are also discussed
Nonabelian Berry Phases in Baryons
We show how generic nonabelian gauge fields can be induced in baryons when a
hierarchy of fast degrees of freedom is integrated out. We identify them with
nonabelian Berry potentials and discuss their role in transmuting quantum
numbers in bag and soliton models of baryons. The resulting baryonic spectra
for both light and heavy quark systems are generic and resemble closely the
excitation spectrum of diatomic molecules. The symmetry restoration in the
system, i.e., the electronic rotational invariance in diatomic molecules, the
heavy-quark symmetry in heavy baryons etc. is interpreted in terms of the
vanishing of nonabelian Berry potentials that otherwise govern the hyperfine
splitting.Comment: Latex 35 pages (2 figures not added, will be faxed if requested),
NTG-92-2
Anomalous Chiral Fermi Surface
We provide a geometrical argument for the emergence of a Wess-Zumino-Witten
(WZW) term for a Fermi surface threaded by a Berry curvature. In the presence
of external fields, the gauged WZW term yields a chiral (triangle) anomaly for
the fermionic current at the edge of the Fermi surface. Fermion number is
conserved though since the Berry curvatures occur always in pairs with opposite
(monopole) charge. The anomalous vector and axial currents for a a fermionic
fluid at low temperature threaded by pairs of Berry curvatures are discussed.
The leading temperature correction to the chiral vortical effect in a slowly
rotating Fermi surface threaded by a Berry curvature maybe tied to the
gravitational anomaly.Comment: 4 pages; version to appear in PR
- …