174 research outputs found
Classical and Quantized Tensionless Strings
{}From the ordinary tensile string we derive a geometric action for the
tensionless () string and discuss its symmetries and field equations. The
Weyl symmetry of the usual string is shown to be replaced by a global
space-time conformal symmetry in the limit. We present the explicit
expressions for the generators of this group in the light-cone gauge. Using
these, we quantize the theory in an operator form and require the conformal
symmetry to remain a symmetry of the quantum theory. Modulo details concerning
zero-modes that are discussed in the paper, this leads to the stringent
restriction that the physical states should be singlets under space-time
diffeomorphisms, hinting at a topological theory. We present the details of the
calculation that leads to this conclusion.Comment: 34 pages, Latex, USITP 93-1
Momentum Analyticity and Finiteness of the 1-Loop Superstring Amplitude
The Type II Superstring amplitude to 1-loop order is given by an integral of
-functions over the moduli space of tori, which diverges for real
momenta. We construct the analytic continuation which renders this amplitude
well defined and finite, and we find the expected poles and cuts in the complex
momentum plane.Comment: 10pp, /UCLA/93/TEP/
Tensionless strings: physical Fock space and higher spin fields
I study the physical Fock space of the tensionless string theory with
perimeter action, exploring its new gauge symmetry algebra. The cancellation of
conformal anomaly requires the space-time to be 13-dimensional. All particles
are massless and there are no tachyon states in the spectrum. The zero mode
conformal operator defines the levels of the physical Fock space. All levels
can be classified by the highest Casimir operator W of the little group E(11)
for massless particles in 11-dimensions. The ground state is infinitely
degenerated and contains massless gauge fields of arbitrary large integer spin,
realizing the irreducible representations of E(11) of fixed helicity. The
excitation levels realize CSR representations of little group E(11) with an
infinite number of helicities. After inspection of the first excitation level,
which, as I prove, is a physical null state, I conjecture that all excitation
levels are physical null states. In this theory the tensor field of the second
rank does not play any distinctive role and therefore one can suggest that in
this model there is no gravity.Comment: 22 pages, Latex, references adde
Decay of long-lived massive closed superstring states: Exact results
We find a one-parameter family of long-lived physical string states in type
II superstring theory. We compute the decay rate by an exact numerical
evaluation of the imaginary part of the one-loop propagator. Remarkably, the
lifetime rapidly increases with the mass. We find a power-law dependence of the
form , where the value of depends on
the parameter characterizing the state. For the most stable state in this
family, one has . The dominant decay channel of these massive
string states is by emission of soft massless particles. The quantum states can
be viewed semiclassically as closed strings which cannot break during the
classical evolution.Comment: Latex, 5 figures, 35 pages (= 23 pages + appendices). Minor
correction
Finite N Index and Angular Momentum Bound from Gravity
We exactly compute the finite N index and BPS partition functions for N=4 SYM
theory in a newly proposed maximal angular momentum limit. The new limit is not
predicted from the superconformal algebra, but naturally arises from the
supergravity dual. We show that the index does not receive any finite N
corrections while the free BPS partition function does.Comment: 14 pages, v2: minor revisions, published versio
From Free Fields to AdS -- II
We continue with the program of hep-th/0308184 to implement open-closed
string duality on free gauge field theory (in the large limit). In this
paper we consider correlators such as \la \prod_{i=1}^n
\Tr\Phi^{J_i}(x_i)\ra. The Schwinger parametrisation of this -point
function exhibits a partial gluing up into a set of basic skeleton graphs. We
argue that the moduli space of the planar skeleton graphs is exactly the same
as the moduli space of genus zero Riemann surfaces with holes. In other
words, we can explicitly rewrite the -point (planar) free field correlator
as an integral over the moduli space of a sphere with holes. A preliminary
study of the integrand also indicates compatibility with a string theory on
. The details of our argument are quite insensitive to the specific form
of the operators and generalise to diagrams of higher genus as well. We take
this as evidence of the field theory's ability to reorganise itself into a
string theory.Comment: 26 pages, 2 figures; v2. some additional comments, references adde
Numerical Study of the Two Color Attoworld
We consider QCD at very low temperatures and non-zero quark chemical
potential from lattice Monte Carlo simulations of the two-color theory in a
very small spatial volume (the attoscale). In this regime the quark number
rises in discrete levels in qualitative agreement with what is found
analytically at one loop on S3xS1 with radius R_S3 << 1/{\Lambda}_QCD. The
detailed level degeneracy, however, cannot be accounted for using weak coupling
arguments. At each rise in the quark number there is a corresponding spike in
the Polyakov line, also in agreement with the perturbative results. In addition
the quark number susceptibility shows a similar behaviour to the Polyakov line
and appears to be a good indicator of a confinement-deconfinement type of
transition.Comment: 18 pages, 10 figure
Hot String Soup
Above the Hagedorn energy density closed fundamental strings form a long
string phase. The dynamics of weakly interacting long strings is described by a
simple Boltzmann equation which can be solved explicitly for equilibrium
distributions. The average total number of long strings grows logarithmically
with total energy in the microcanonical ensemble. This is consistent with
calculations of the free single string density of states provided the
thermodynamic limit is carefully defined. If the theory contains open strings
the long string phase is suppressed.Comment: 13 pages, no figures, uses LaTex, some errors in equations have been
corrected, NSF-ITP-94-83, UCSBTH-94-3
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