4,435 research outputs found
Topological Terms in String Theory on Orbifolds
We study toroidal orbifold models with topologically invariant terms in the
path integral formalism and give physical interpretations of the terms from an
operator formalism point of view. We briefly discuss a possibility of a new
class of modular invariant orbifold models.Comment: 15pages,LaTex,KOBE-TH-94-0
A New Mechanism of Spontaneous SUSY Breaking
We propose a new mechanism of spontaneous supersymmetry breaking. The
existence of extra dimensions with nontrivial topology plays an important role.
We investigate new features resulted from the mechanism in two simple
supersymmetric Z_2 and U(1) models. One of remarkable features is that there
exists a phase in which the translational invariance for the compactified
directions is broken spontaneously, accompanying the breakdown of the
supersymmetry. The mass spectrum of the models appeared in reduced dimensions
is a full of variety, reflecting the highly nontrivial vacuum structure of the
models. The Nambu-Goldstone bosons (fermions) associated with breakdown of
symmetries are found in the mass spectrum. Our mechanism also yields quite
different vacuum structures if models have different global symmetries.Comment: 43 pages, 3 figure
Hadron-quark continuity induced by the axial anomaly in dense QCD
We investigate the interplay between the chiral and diquark condensates on
the basis of the Ginzburg-Landau potential with QCD symmetry. We demonstrate
that the axial anomaly drives a new critical point at low temperature in the
QCD phase diagram and leads to a smooth crossover between the hadronic and
color superconducting phases.Comment: 4 pages, 5 figures, to appear in the Proceedings of Quark Matter 2006
held in Shangha
Identification of hydrogen bonds using quantum electrodynamics
A method for the identification of hydrogen bonds was investigated from the viewpoint of the stress tensor density proposed by Tachibana and following other works in this field. Hydrogen bonds are known to exhibit common features with ionic and covalent bonds. In quantum electrodynamics, the covalent bond has been demonstrated to display a spindle structure of the stress tensor density. Importantly, this spindle structure is also seen in the hydrogen bond, although the covalency is considerably weaker than in a typical covalent bond. Distinguishing it from the ionic bond is most imperative for the identification of the hydrogen bond. In the present study, the directionality of the hydrogen bond is investigated as the ionic bond is nearly isotropic, while the hydrogen bond exhibits the directionality. It was demonstrated that the hydrogen bond can be distinguished from the ionic bond using the angle dependence of the largest eigenvalue of the stress tensor density
Thermal Phase Transitions and Gapless Quark Spectra in Quark Matter at High Density
Thermal color superconducting phase transitions in three-flavor quark matter
at high baryon density are investigated in the Ginzburg-Landau (GL) approach.
We constructed the GL potential near the boundary with a normal phase by taking
into account nonzero quark masses, electric charge neutrality, and color charge
neutrality. We found that the density of states averaged over paired quarks
plays a crucial role in determining the phases near the boundary. By performing
a weak coupling calculation of the parameters characterizing the GL potential
terms of second order in the pairing gap, we show that three successive
second-order phase transitions take place as the temperature increases: a
modified color-flavor locked phase (ud, ds, and us pairings) -> a ``dSC'' phase
(ud and ds pairings) -> an isoscalar pairing phase (ud pairing) -> a normal
phase (no pairing). The Meissner masses of the gluons and the number of gapless
quark modes are also studied analytically in each of these phases.Comment: 15 pages, 6 figure
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
Melting Pattern of Diquark Condensates in Quark Matter
Thermal color superconducting phase transitions in high density three-flavor
quark matter are investigated in the Ginzburg-Landau approach. Effects of
nonzero strange quark mass, electric and color charge neutrality, and direct
instantons are considered. Weak coupling calculations show that an interplay
between the mass and electric neutrality effects near the critical temperature
gives rise to three successive second-order phase transitions as the
temperature increases: a modified color-flavor locked (mCFL) phase (ud, ds, and
us pairings) -> a ``dSC'' phase (ud and ds pairings) -> an isoscalar pairing
phase (ud pairing) -> a normal phase (no pairing). The dSC phase is novel in
the sense that while all eight gluons are massive as in the mCFL phase, three
out of nine quark quasiparticles are gapless.Comment: minor changes in the text, fig.2 modifie
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