46220325
Calculating the rest tension for a polymer of string bits.
We explore the application of approximation schemes from many body physics, including the Hartree-Fock method and random phase approximation (RPA), to the problem of analyzing the low energy excitations of a polymer chain made up of bosonic string bits. We accordingly obtain an expression for the rest tension [ital T][sub 0] of the bosonic relativistic string in terms of the parameters characterizing the microscopic string bit dynamics. We first derive an exact connection between the string tension and a certain correlation function of the many-body string bit system. This connection is made for an arbitrary interaction potential between string bits and relies on an exact dipole sum rule. We then review an earlier calculation by Goldstone of the low energy excitations of a polymer chain using the RPA. We assess the accuracy of the RPA by calculating the first-order corrections. For this purpose we specialize to the unique scale-invariant potential, namely, an attractive [delta]-function potential in two (transverse) dimensions. We find that the corrections are large, and discuss a method for summing the large terms. The corrections to this improved RPA are roughly 15%.
119202259
Open string Regge trajectory and its field theory limit
We study the properties of the leading Regge trajectory in open string theory including the open string planar one-loop corrections. With $SU(N)$ Chan-Paton factors, the sum over planar open string multiloop diagrams describes the 't Hooft limit $N\ensuremath{\rightarrow}\ensuremath{\infty}$ with $N{g}_{s}^{2}$ fixed. Our motivation is to improve the understanding of open string theory at finite ${\ensuremath{\alpha}}^{\ensuremath{'}}$ as a model of gauge field theories. $SU(N)$ gauge theories in $D$ space-time dimensions are described by requiring open strings to end on a stack of $N$ $\mathrm{D}p$-branes of space-time dimension $D=p+1$. The large $N$ leading trajectory $\ensuremath{\alpha}(t)=1+{\ensuremath{\alpha}}^{\ensuremath{'}}t+\ensuremath{\Sigma}(t)$ can be extracted, through order ${g}^{2}$, from the $s\ensuremath{\rightarrow}\ensuremath{-}\ensuremath{\infty}$ limit, at fixed $t$, of the four open string tree and planar loop diagrams. We analyze the $t\ensuremath{\rightarrow}0$ behavior with the result that $\ensuremath{\Sigma}(t)\ensuremath{\sim}\ensuremath{-}C{g}^{2}(\ensuremath{-}{\ensuremath{\alpha}}^{\ensuremath{'}}t{)}^{(D\ensuremath{-}4)/2}/(D\ensuremath{-}4)$. This result precisely tracks the 1-loop Reggeized gluon of gauge theory in $Dg4$ space-time dimensions. In particular, for $D\ensuremath{\rightarrow}4$ it reproduces the known infrared divergences of gauge theory in 4 dimensions with a Regge trajectory behaving as $\ensuremath{-}\mathrm{ln}﻿(\ensuremath{-}{\ensuremath{\alpha}}^{\ensuremath{'}}t)$. We also study $\ensuremath{\Sigma}(t)$ in the limit $t\ensuremath{\rightarrow}\ensuremath{-}\ensuremath{\infty}$ and show that, when $Dl8$, it behaves as ${\ensuremath{\alpha}}^{\ensuremath{'}}t/(\mathrm{ln}﻿(\ensuremath{-}{\ensuremath{\alpha}}^{\ensuremath{'}}t){)}^{\ensuremath{\gamma}}$, where $\ensuremath{\gamma}g0$ depends on $D$ and the number of massless scalars. Thus, as long as $4lDl8$, the 1-loop correction stays small relative to the tree trajectory for $\ensuremath{-}{\ensuremath{\alpha}}^{\ensuremath{'}}t$ arbitrarily large. Finally we present the results of numerical calculations of $\ensuremath{\Sigma}(t)$ for all negative $t$.
121644848
Scattering of one-dimensional bags in the interacting string formalism
15723382
Quantum Newtonian dynamics on a light front
We recall the special features of quantum dynamics on a light front (in an infinite momentum frame) in string and field theory. The reason this approach is more effective for string than for fields is stressed: the light-front dynamics for string is that of a true Newtonian many particle system, since a string bit has a fixed Newtonian mass. In contrast, each particle of a field theory has a variable Newtonian mass P{sup +}; so the Newtonian analogy actually requires an infinite number of species of elementary Newtonian particles. This complication substantially weakens the value of the Newtonian analogy in applying light-front dynamics to nonperturbative problems. Motivated by the fact that conventional field theories can be obtained as infinite tension limits of string theories, we propose a way to recast field theory as a standard Newtonian system. We devise and analyze some simple quantum mechanical systems that display the essence of the proposal, and we discuss prospects for applying these ideas to large N{sub c} QCD. {copyright} {ital 1998} {ital The American Physical Society}
122367974
Symmetry patterns in the mass spectra of dual string models
Abstract We develop techniques for analyzing the rotation and gauge group representation content of string models. We explicitly construct all rotation group representations at low mass levels. We then obtained simple approximate formulas for the degeneracy of any given rotation or gauge group representation in the limit of very high mass. We also derive generating functions that give exactly the degeneracy of a representation at any mass level. Finally, we numerically study these results in several cases, and then abstract from the numerical data some simple empirical rules relating different representations.
121484584
EMBRYONIC DUAL MODEL FOR PIONS AND FERMIONS.
1684356
Exclusive photodisintegration of 3He with polarized photons.
The first measurement of exclusive photodisintegration of [sup 3]He with polarized photons is reported. Cross sections and asymmetries for [sup 3]He([rvec ]gg,[ital pn])[ital p] and [sup 3]He([rvec ]gg,[ital pp])[ital n] at 235[le][ital E][sub [gamma]][le]305 MeV are compared to a theoretical calculation which includes one-, two-, and three-nucleon photon absorption. Two-nucleon absorption dominates the [ital pn] data, but is suppressed in the [ital pp] data. The [ital pp] data require the inclusion of three-nucleon absorption to describe the cross section and beam asymmetry over all momenta.
32938508
Polarized Compton scattering from the proton.