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.
119439619
COSMIC STRING SPACETIME IN DILATON GRAVITY AND FLAT ROTATION CURVES
In dilaton gravity theories, we consider a string-like topological defect formed during U(1) gauge symmetry-breaking phase transition in the early Universe, and far from the cosmic string we have vacuum solutions of the generalized Einstein equation. We discuss how they can be related to the flatness of galactic rotation curves.
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.
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.
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.
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.
1624418
String field theory and perturbative dynamics of noncommutative field theory
Abstract The perturbative dynamics of noncommutative field theory (NCFT) is discussed from a point view of string field theory. As in the commutative case it is inevitable to introduce a closed string, which may be described as a bound state of two noncommutative open strings. We point out that the closed string, interacting nontrivially with the open string, plays an essential role in the ultraviolet region. The contribution of the closed string is responsible for the discrepancy between the NCFT and the string field theory. It clarifies the controversial issues associated with the ultraviolet/infrared (UV/IR) behaviour of the perturbative dynamics of the NCFT.
16869054
Applications of Thirring Model to Inhomogenous Rolling Tachyon and Dissipative Quantum Mechanics
We study the rolling tachyon and the dissipative quantum mechanics using the Thirring model with a boundary mass. We construct a boundary state for the dissipative quantum system in one dimension, which describes the system at the off-critical points as well as at the critical point. Then we extend the Thirring model with a boundary mass in order to depict the time evolution of an unstable D-branes with one direction wrapped on a circle of radius R, which is termed the inhomogeneous rolling tachyon. The analysis based on the Thirring model shows that the time dependent evolution of the inhomogeneous tachyon is possible only when 2/(3)1/2 < R < 2.
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.
15345099
Colliding Waves on a Brane, the Big Bounce and Reconnection
We present a time-dependent solution of the Nambu-Goto action which represents two colliding waves moving at the speed of light. This solution can be decomposed into two distinct regions with different geometries corresponding to shrinking or expanding brane universe and two colliding branes. The former describes the Big Bounce without singularity while the latter describes that two branes collide and reconnect to each other. The colliding brane region has a signature change. Classical dynamics of a massive particle on the brane is studied through the geodesics.
16285153
Tachyon condensation and open string field theory
Abstract We perform canonical quantization of open string on a unstable D-brane in the background of tachyon condensation. Evaluating the Polyakov path-integral on a strip, we obtain a field theoretical propagator in the open string theory. As condensation occurs the string field theory is continuously deformed. At the infrared fixed point of condensation, the open string field on the unstable D-brane transmutes to that on the lower-dimensional D-brane with the correct D-brane tension.