118497382
Degeneracy pressure of relic neutrinos and cosmic coincidence problem
We consider the universe as a huge νR-sphere formed with degenerate relic neutrinos and suggest that its constant energy density play a role of an effective cosmological constant. We construct the sphere as a bubble of true vacuum in a field theory model with a spontaneously broken U(1) global symmetry, and we interpret the sphere-forming time as the transition time for recent acceleration of the universe. The coincidence problem may be regarded as naturally resolved in this model, because the relic neutrinos can make the νR-sphere at the recent past time during the matter-dominated era.
119272116
Light bending by nonlinear electrodynamics under strong electric and magnetic field
We calculate the bending angles of light under the strong electric and magnetic fields by a charged black hole and a magnetized neutron star according to the nonlinear electrodynamics of Euler-Heisenberg interaction. The bending angle of light by the electric field of charged black hole is computed from geometric optics and a general formula is derived for light bending valid for any orientation of the magnetic dipole. The astronomical significance of the light bending by magnetic field of a neutron star is discussed.
16719442
Chiral vacuum alignment in dense QCD
Abstract We discuss an interesting possibility of nontrivial, quark-mass induced chiral vacuum alignment in color–flavor locking phase of cold, dense QCD. With the simplifying assumption that the gaps for quarks are identical to those of antiquarks and the light quark masses are given by m u = m d and m s / m d =15, we find the true chiral vacuum can align only to one of the discrete number of directions in the continuum of chiral vacua. The alignment depends on the size of the diquark condensates, and the vacuum transitions between the discrete vacua caused by the evolution of the diquark condensates can be first order phase transition with vanishing or nonvanishing latent heat, depending on the vacua involved. It is also shown that as μ →∞, where μ is the baryon chemical potential, parity is spontaneously broken through the vacuum alignment.
119660786
Baryon number violation in dense matter. On the relation with anomalous high energy scattering
Abstract The recent claim of the equivalence of baryon number violation in dense matter and that of high energy scattering is examined. We present a plausible argument against the claim. We also calculate the anomalous decay rate of dense matter to (μ/E 0 ) 8 3 In (μ/E 0 ) order. To this order, we find the anomalous decay rate is completely equivalent to the anomalous cross section of the high energy scattering calculated by the valley method.
14559352
Estimating higher order perturbative coefficients using Borel transform
A new method of estimating higher order perturbative coefficients is discussed. It exploits the rapid, asymptotic growth of perturbative coefficients and the information on the singularities in the complex Borel plane. A comparison with other methods is made in several Quantum Chromodynamics (QCD) expansions.
3172088
RAPIDITY GAP OF WEAKLY COUPLED LEPTOQUARK PRODUCTION IN ep COLLIDER
We show that the current bounds on the leptoquark couplings imply that if leptoquarks are produced in ep collisions, a significant fraction of them could form a leptoquark–quark bound state. The decay of the bound state has a distinct event shape with rapidity gap. A possible application of this observation in the leptoquark search at HERA is discussed.
14504724
Canonical quantization of open string and noncommutative geometry
We perform canonical quantization of open strings in the $D$-brane background with a $B$-field. Treating the mixed boundary condition as a primary constraint, we get a set of secondary constraints. Then these constraints are shown to be equivalent to orbifold conditions to be imposed on normal string modes. These orbifold conditions are a generalization of the familiar orbifold conditions which arise when we describe open strings in terms of closed strings. Solving the constraints explicitly, we obtain a simple Hamiltonian for the open string, which reveals the nature of noncommutativity transparently.
124705504
TIME-DEPENDENT SOLUTIONS OF 5D VACUUM EINSTEIN EQUATIONS WITH COSMOLOGICAL CONSTANT
We solve vacuum field equations in five-dimensional gravity with cosmological constant to determine the time-dependence of the Robertson–Walker scale factor. We discuss its cosmological implications.
15486524
Boundary String Field Theory at One-loop
We discuss the open string one-loop partition function in tachyon condensation background of a unstable D-brane system. We evaluate the partition function by using the boundary state formulation and find that it is in complete agreement with the result obtained in the boundary string field theory. It suggests that the open string higher loop diagrams may be produced consistently by a closed string field theory, where the D-brane plays a role of source for the closed string field.
119371484
Open Superstring and Noncommutative Geometry
We perform canonical quantization of the open Neveu-Schwarz-Ramond (NSR) superstrings in the background of a D-brane with the NS B-field. If we choose the mixed boundary condition as a primary constraint, it generates a set of secondary constraints. These constraints are easily solved and as a result, the noncommutative geometry in the bosonic string theory is extended to the superspace. Solving the constraint conditions we also find that the Hamiltonian for the superstring is equivalent to a free superstring Hamiltonian on the target space with the effective open string metric G.
123683308
STRING THEORY AND DUALITIES IN THE QUANTUM DISSIPATIVE HOFSTADTER SYSTEM
We study the dualities of the quantum dissipative Hofstadter system which describes particles moving in two dimensions, subject to a uniform magnetic field, a periodic potential and a dissipative force. Using the string theory formulation, we show that the system has two kinds of dualities. The duality, previously known as the exact duality in the literature is shown to correspond to a subgroup of the T-dual symmetry group unbroken by the periodic boundary potential in string theory. The other duality is a particle–kink duality in the noncommutative open string theory which is a generalized Schmid duality in the presence of the uniform magnetic field. The kinks of the dissipative Hofstadter model are found to be noncommutative objects. The particle–kink duality, which is called previously the approximate duality, is shown to be also exact. In contrast to the previous derivation, which is based on the Coulomb gas expansion of the partition function and asserts that the duality holds only approximately in t...