20 research outputs found
Orbifold equivalence for finite density QCD and effective field theory
In the large N_c limit, some apparently different gauge theories turn out to
be equivalent due to large N_c orbifold equivalence. We use effective field
theory techniques to explore orbifold equivalence, focusing on the specific
case of a recently discovered relation between an SO(2N_c) gauge theory and
QCD. The equivalence to QCD has been argued to hold at finite baryon chemical
potential, \mu_B, so long as one deforms the SO(2N_c) theory by certain
"double-trace" terms. The deformed SO(2N_c) theory can be studied without a
sign problem in the chiral limit, in contrast to SU(N_c) QCD at finite \mu_B.
The purpose of the double-trace deformation in the SO(2N_c) theory is to
prevent baryon number symmetry from breaking spontaneously at finite density,
which is necessary for the equivalence to large N_c QCD to be valid. The
effective field theory analysis presented here clarifies the physical
significance of double-trace deformations, and strongly supports the proposed
equivalence between the deformed SO(2N_c) theory and large N_c QCD at finite
density.Comment: 39 pages, 5 figures, 2 tables. v2: Minor typo fixes and
clarification
The phases of deuterium at extreme densities
We consider deuterium compressed to higher than atomic, but lower than
nuclear densities. At such densities deuterium is a superconducting quantum
liquid. Generically, two superconducting phases compete, a "ferromagnetic" and
a "nematic" one. We provide a power counting argument suggesting that the
dominant interactions in the deuteron liquid are perturbative (but screened)
Coulomb interactions. At very high densities the ground state is determined by
very small nuclear interaction effects that probably favor the ferromagnetic
phase. At lower densities the symmetry of the theory is effectively enhanced to
SU(3), and the quantum liquid enters a novel phase, neither ferromagnetic nor
nematic. Our results can serve as a starting point for investigations of the
phase dynamics of deuteron liquids, as well as exploration of the stability and
dynamics of the rich variety of topological objects that may occur in phases of
the deuteron quantum liquid, which range from Alice strings to spin skyrmions
to Z_2 vortices.Comment: 9 pages, 6 figures; v2: fixed typo
Project X: Physics Opportunities
Part 2 of "Project X: Accelerator Reference Design, Physics Opportunities, Broader Impacts". In this Part, we outline the particle-physics program that can be achieved with Project X, a staged superconducting linac for intensity-frontier particle physics. Topics include neutrino physics, kaon physics, muon physics, electric dipole moments, neutron-antineutron oscillations, new light particles, hadron structure, hadron spectroscopy, and lattice-QCD calculations. Part 1 is available as arXiv:1306.5022 [physics.acc-ph] and Part 3 is available as arXiv:1306.5024 [physics.acc-ph]