219 research outputs found
Chiral magnetic superconductivity
Materials with charged chiral quasiparticles in external parallel electric
and magnetic fields can support an electric current that grows linearly in
time, corresponding to diverging DC conductivity. From experimental viewpoint,
this "Chiral Magnetic Superconductivity" (CMS) is thus analogous to
conventional superconductivity. However the underlying physics is entirely
different -- the CMS does not require a condensate of Cooper pairs breaking the
gauge degeneracy, and is thus not accompanied by Meissner effect. Instead, it
owes its existence to the (temperature-independent) quantum chiral anomaly and
the conservation of chirality. As a result, this phenomenon can be expected to
survive to much higher temperatures. Even though the chirality of
quasiparticles is not strictly conserved in real materials, the chiral magnetic
superconductivity should still exhibit itself in AC measurements at frequencies
larger than the chirality-flipping rate, and in microstructures of Dirac and
Weyl semimetals with thickness below the mean chirality-flipping length that is
about 1-100 m. In nuclear physics, the CMS should contribute to the
charge-dependent elliptic flow in heavy ion collisions.Comment: 7 pages, to appear in the Proceedings of the XII Quark Confinement
and the Hadron Spectrum conference, Thessaloniki, Greece, August 29 -
September 3, 201
The Glueball Filter in Central Production and Broken Scale Invariance
We propose a possible explanation of the kinematical dependence of the
central production of the scalar glueball candidate observed recently by the
WA91 and WA102 Collaborations, and discussed by Close and Kirk, in the context
of the broken scale invariance of QCD. The dependences of glueball production
on the transverse momenta and azimuthal angles of the final-state protons may
be related to the structure of the trace anomaly in QCD.Comment: 9 pages, 2 figures, LaTeX2
Broken scale invariance, massless dilaton and confinement in QCD
Classical conformal invariance of QCD in the chiral limit is broken
explicitly by scale anomaly. As a result, the lightest scalar particle (scalar
glueball, or dilaton) in QCD is not light, and cannot be described as a
Goldstone boson. Nevertheless basing on an effective low-energy theory of
broken scale invariance we argue that inside the hadrons the non-perturbative
interactions of gluon fields result in the emergence of a massless dilaton
excitation (which we call the "scalaron"). We demonstrate that our effective
theory of broken scale invariance leads to confinement. This theory allows a
dual formulation as a classical Yang-Mills theory on a curved conformal
space-time background. Possible applications are discussed, including the
description of strongly coupled quark-gluon plasma and the spin structure of
hadrons.Comment: 18 pages, 2 figures; v2: fixed numerous typo
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