The Leading Eikonal Operator in String-Brane Scattering at High Energy

Abstract

In this paper we present two (a priori independent) derivations of the eikonal operator in string-brane scattering. The first one is obtained by summing surfaces with any number of boundaries, while in the second one the eikonal operator is derived from the three-string vertex in a suitable light-cone gauge. This second derivation shows that the bosonic oscillators present in the leading eikonal operator are to be identified with the string bosonic oscillators in a suitable light-cone gauge, while the first one shows that it exponentiates recovering unitarity. This paper is a review of results obtained in Refs. Talk given by one of us (PDV) at the conference BUDS2013, Breaking of supersymmetry and Ultraviolet Divergences in extended Supergravity, National Laboratories of Frascati, March 25-28, 2013.

(Non-adiabatic) string creation on nice slices in Schwarzschild black holes

“…Using (20) and (22) to compute the asymptotic values of ω n (T ) we note that the function dr/dT goes to the constant value √ C 2 − 1/C for T → −∞ and approaches zero for T → ∞. The asymptotic values of ω n (T ) in the far past, ω in n , and far future, ω out n , are then given by…”

“…For our string production problem this means that the out state is strictly speaking not well-defined and we cannot compute |β n | 2 by solving the wave equation (5) for the nice slice frequency ω(T ). This 22 Note, however, that the total number of particles produced is still finite once we integrate over all the k-modes:…”

“…See also references[16][17][18][19][20][21][22][23][24] 4. In[25] one of the authors studied whether the formation of a horizon could be avoided altogether through quantum tunneling of matter (branes) into horizon-size microstate geometries.…”

A microscopic description of absorption in high-energy string-brane collisions

“…In this regime we are still able to provide an exactly unitary S-matrix, but unitarity now works in an enlarged Hilbert space containing excited closed strings besides the incoming one. In [5,6] (see also [8,9]) the microscopic structure of this S-matrix was analyzed in much detail.…”

“…In a series of relatively recent papers [4][5][6][7] we have addressed the problem of the highenergy collision of a closed string off a configuration of parallel Dp-branes. By suitably playing with the various parameters characterizing the process, the number N of branes, the energy E and impact parameter b of the collision, as well as the string coupling g s , we could identify [4] a region in parameter space inside which closed string loops can be safely neglected and, consequently, there is no closed string production or gravitational bremsstrahlung, a considerable simplification.…”