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.
119490078
Why there is no spin-orbit inversion in heavy-light mesons
We show that the absence of spin-orbit inversions in heavy-light mesons can be explained by the chiral radiative corrections in potential model. A new potential model estimate is given of the masses for P-wave bottom mesons.
15649201
Higher order corrections to Color superconducting gaps
Abstract We find a (nonlocal) gauge where the wavefunction renormalization constant does not get any corrections for all momenta in the hard-dense loop approximation. In this gauge, we solve the Schwinger–Dyson equations for the diquark condensate in dense QCD to calculate the Cooper-pair gap. We determine not only the exponent but also the prefactor of the gap in a gauge independent way. We find that the higher order corrections increase the gap only by about 1.6 times to the leading order gap at Coulomb gauge.
119286280
LIGHT BENDING IN A COULOMBIC FIELD
The nonlinear Euler–Heisenberg interaction bends light toward an electric charge. The bending angle and trajectory of light in a Coulombic field are computed in geometric optics.
39461914
Heavy quark mass determination from the quarkonium ground state energy: a pole mass approach
The heavy quark pole mass in perturbation theory suffers from a renormalon caused, inherent uncertainty of O(?QCD). This fundamental difficulty of determining the pole mass to an accuracy better than the inherent uncertainty can be overcome by direct resummation of the first infrared renormalon. We show how a properly defined pole mass as well as the mass for the top and bottom quarks can be determined accurately from the O(m?s5) quarkonium ground state energy.
119333632
Direct resummation of the leading renormalons in inclusive semileptonic B decay
We present a Borel resummation method for the QCD corrections in inclusive, charmless, semileptonic B-meson decay. The renormalon contributions are resummed to all orders by employing a bilocal expansion of the Borel transform that accurately accounts for the first infrared renormalons in the Borel plane. The renormalons in the pole mass and the QCD expansion are resummed separately, and a precise relation is obtained between a properly defined pole mass and the MS mass. The inclusive decay rate is calculated to three-loop order using an estimate of the yet unknown NNLO coefficient.
12710825
Coherent state quantization of SU(N) non-Abelian Chern-Simons particles
Abstract We present a new method of formulating the classical theory of SU( N + 1) non-Abelian Chern-Simons (NACS) particles for arbitrary N ⩾ 1 using the symplectic reduction of CP( N ) manifold from S 2 N +1 . Quantizing the theory using BRST formulation and coherent state path integral method, we obtain a quantum mechanical model for SU( N + 1) NACS particles.
118939493
The final fate of the rolling tachyon
We propose an alternative interpretation of the boundary state for the rolling tachyon, which may depict the time evolution of unstable D-branes in string theory. Splitting the string variable in the temporal direction into the classical part, which we may call ``time and the quantum one, we observe the time dependent behaviour of the boundary. Using the fermion representation of the rolling tachyon boundary state, we show that the boundary state correctly describes the time-dependent decay process of the unstable D-brane into a S-brane at the classical level.
15214626
(2+1) Dimensional Black Hole and (1+1) Dimensional Quantum Gravity
In the Chern-Simons gauge theory formulation of the spinning (2+1) dimensional black hole, we may treat the horizon and the spatial infinity as boundaries. We obtain the actions induced on both boundaries, applying the Faddeev and Shatashvili procedure. The action induced on the boundary of the horizon is precisely the gauged $SL(2,R)/U(1)$ Wess-Zumino-Witten (WZW) model, which has been studied previously in connection with a Lorentz signature black hole in (1+1) dimensions. The action induced on the boundary of spatial infinity is also found to be a gauged $SL(2,R)$ WZW model, which is equivalent to the Liouville model, the covariant action for the (1+1) dimensional quantum gravity. Thus, the (2+1) dimensional black hole is intimately related to the quantum gravity in (1+1) dimensions.
119489587
Fermion representation of the rolling tachyon boundary conformal field theory
A free fermion representation of the rolling tachyon boundary conformal field theory is constructed. The representation is used to obtain an explicit, compact, exact expression for the boundary state. We use the boundary state to compute the disc and cylinder amplitudes for the half-S-brane.
119342247
Noncommutative Dirac–Born–Infeld action for D-brane
Abstract We derive the noncommutative Dirac–Born–Infeld action for the D -brane, which governs dynamics of D -brane with a NS-NS B -field in the low energy regime. Depending on some details of the path integral prescriptions, both ordinary Dirac–Born–Infeld action and noncommutative one can be obtained by evaluating the same Polyakov string path integral for the open string ending on the D -brane. Thus, it establishes the equivalence of the noncommutative Dirac–Born–Infeld action and the ordinary one.