527 research outputs found
Spectral Continuity in Dense QCD
The vector mesons in three-flavor quark matter with chiral and diquark
condensates are studied using the in-medium QCD sum rules. The diquark
condensate leads to a mass splitting between the flavor-octet and
flavor-singlet channels. At high density, the singlet vector meson disappears
from the low-energy spectrum, while the octet vector mesons survive as light
excitations with a mass comparable to the fermion gap. A possible connection
between the light gluonic modes and the flavor-octet vector mesons at high
density is also discussed.Comment: 4 pages, 3 figures; version to appear in Phys. Rev.
New Critical Point Induced by the Axial Anomaly in Dense QCD
We study the interplay between chiral and diquark condensates within the
framework of the Ginzburg-Landau free energy, and classify possible phase
structures of two and three-flavor massless QCD. The QCD axial anomaly acts as
an external field applied to the chiral condensate in a color superconductor
and leads to a crossover between the broken chiral symmetry and the color
superconducting phase, and, in particular, to a new critical point in the QCD
phase diagram.Comment: 4 pages, 4 figures included, version to appear in Phys. Rev. Let
Higgs Mass and Muon Anomalous Magnetic Moment in Supersymmetric Models with Vector-Like Matters
We study the muon anomalous magnetic moment (muon g-2) and the Higgs boson
mass in a simple extension of the minimal supersymmetric (SUSY) Standard Model
with extra vector-like matters, in the frameworks of gauge mediated SUSY
breaking (GMSB) models and gravity mediation (mSUGRA) models. It is shown that
the deviation of the muon g-2 and a relatively heavy Higgs boson can be
simultaneously explained in large tan-beta region. (i) In GMSB models, the
Higgs mass can be more than 135 GeV (130 GeV) in the region where muon g-2 is
consistent with the experimental value at the 2 sigma (1 sigma) level, while
maintaining the perturbative coupling unification. (ii) In the case of mSUGRA
models with universal soft masses, the Higgs mass can be as large as about 130
GeV when muon g-2 is consistent with the experimental value at the 2 sigma
level. In both cases, the Higgs mass can be above 140 GeV if the g-2 constraint
is not imposed.Comment: 26 pages; 7 figures; corrected typos; minor change
Color Superconductivity from Supersymmetry
A supersymmetric composite model of color superconductivity is proposed.
Quarks and diquarks are dynamically generated as composite fields by a newly
introduced strong gauge dynamics. It is shown that the condensation of the
scalar component of the diquark supermultiplet occurs when the chemical
potential becomes larger than some critical value. We believe that the model
well captures aspects of the diquark condensate behavior and helps our
understanding of the diquark dynamics in real QCD. The results obtained here
might be useful when we consider a theory composed of quarks and diquarks.Comment: 4 pages, 2 figures, An error in Eq.(10) correcte
Anomalous Hall voltage rectification and quantized spin-wave excitation induced by the simultaneous dc- and rf-current application in Ni81Fe19 wire
An anomalous Hall effect and rectification of a Hall voltage are observed by
applying a radio-frequency (rf) current through a single-layered ferromagnetic
wire located on a coplanar waveguide. The components of the magnetization
precession, both in and perpendicular to the plane, can be detected via the
Hall voltage rectification of the rf current by incorporating an additional
direct (dc) current. In this paper, we propose a phenomenological model, which
describes the time-dependent anisotropic magnetoresistance and time-dependent
planer Hall effect. The nonlinearity of the spin dynamics accompanied by
spin-waves as functions of rf and dc currents is also studied, as well as those
of the magnitude and orientation of the external magnetic field.Comment: 42 pages, 5 figures, submitte
The Decay of the Inflaton in No-scale Supergravity
We study the decay of the inflaton in no-scale supergravity and show that
decay due to the gravitational interactions through supergravity effects is
highly suppressed relative to the case in minimal supergravity or models with a
generic Kahler potential. We also show that decay to gravitinos is suppressed.
We demonstrate that decay and sufficient reheating are possible with the
introduction of a non-trivial gauge kinetic term. This channel may be dominant
in no-scale supergravity, yet yields a re-heating temperature which is low
enough to avoid the gravitino problem while high enough for Big Bang
Nucleosynthesis and baryogenesis.Comment: Added the footnote in the conclusion section which discusses the
constrains on the explicit inflaton couplings to the matter fields via
non-renormalizable operators. To appear in JCA
Phase Diagram of Pressure-Induced Superconductivity in EuFe2As2 Probed by High-Pressure Resistivity up to 3.2 GPa
We have constructed a pressuretemperature () phase diagram of
-induced superconductivity in EuFeAs single crystals, via
resistivity () measurements up to 3.2 GPa. As hydrostatic pressure is
applied, an antiferromagnetic (AF) transition attributed to the FeAs layers at
shifts to lower temperatures, and the corresponding resistive
anomaly becomes undetectable for 2.5 GPa. This suggests that the
critical pressure where becomes zero is about 2.5
GPa. We have found that the AF order of the Eu moments survives up to
3.2 GPa without significant changes in the AF ordering temperature
. The superconducting (SC) ground state with a sharp transition
to zero resistivity at 30 K, indicative of bulk
superconductivity, emerges in a pressure range from 2.5
GPa to 3.0 GPa. At pressures close to but outside the SC phase, the
curve shows a partial SC transition (i.e., zero resistivity is not
attained) followed by a reentrant-like hump at approximately
with decreasing temperature. When nonhydrostatic pressure with a uniaxial-like
strain component is applied using a solid pressure medium, the partial
superconductivity is continuously observed in a wide pressure range from 1.1
GPa to 3.2 GPa.Comment: 7 pages, 6 figures, accepted for publication in Physical Review B,
selected as "Editors' Suggestion
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