54 research outputs found
Semi-classical theory of magnetic quantum oscillations in a two-dimensional multiband canonical Fermi liquid
The semi-classical Lifshitz-Kosevich (LK) description of quantum oscillations
is extended to a multiband two-dimensional Fermi liquid with a constant number
of electrons. The amplitudes of novel oscillations with combination
frequencies, recently predicted and observed experimentally, are analytically
derived and compared with the single-band amplitudes. The combination
amplitudes decay with temperature exponentially faster than the standard
harmonics, and this provides a valuable tool for their experimental
identification.Comment: 3 pages, REVTeX 3.0, one eps-figure included in the tex
Thermodynamics of 2D string theory
We calculate the free energy, energy and entropy in the matrix quantum
mechanical formulation of 2D string theory in a background strongly perturbed
by tachyons with the imaginary Minkowskian momentum
(``Sine-Liouville'' theory). The system shows a thermodynamical behaviour
corresponding to the temperature . We show that the
microscopically calculated energy of the system satisfies the usual
thermodynamical relations and leads to a non-zero entropy.Comment: 13 pages, lanlmac; typos correcte
Energy Quantisation in Bulk Bouncing Tachyon
We argue that the closed string energy in the bulk bouncing tachyon
background is to be quantised in a simple manner as if strings were trapped in
a finite time interval. We discuss it from three different viewpoints; (1) the
timelike continuation of the sinh-Gordon model, (2) the dual matrix model
description of the (1+1)-dimensional string theory with the bulk bouncing
tachyon condensate, (3) the c_L=1 limit of the timelike Liouville theory with
the dual Liouville potential turned on. There appears to be a parallel between
the bulk bouncing tachyon and the full S-brane of D-brane decay. We find the
critical value \lambda_c of the bulk bouncing tachyon coupling which is
analogous to \lambda_o=1/2 of the full S-brane coupling, at which the system is
thought to be at the bottom of the tachyon potential.Comment: 25 pages, minor changes, one reference adde
ZZ brane amplitudes from matrix models
We study instanton contribution to the partition function of the one matrix
model in the k-th multicritical region, which corresponds to the (2,2k-1)
minimal model coupled to Liouville theory. The instantons in the one matrix
model are given by local extrema of the effective potential for a matrix
eigenvalue and identified with the ZZ branes in Liouville theory. We show that
the 2-instanton contribution in the partition function is universal as well as
the 1-instanton contribution and that the connected part of the 2-instanton
contribution reproduces the annulus amplitudes between the ZZ branes in
Liouville theory. Our result serves as another nontrivial check on the
correspondence between the instantons in the one matrix model and the ZZ branes
in Liouville theory, and also suggests that the expansion of the partition
function in terms of the instanton numbers are universal and gives
systematically ZZ brane amplitudes in Liouville theory.Comment: 29 pages, 4 figures; v2:how to scale x is generalized;
v3:introduction and the last section are revised, typos correcte
An Exact Bosonization Rule for c=1 Noncritical String Theory
We construct a string field theory for c=1 noncritical strings using the loop
variables as the string field. We show how one can express the nonrelativistic
free fermions which describes the theory, in terms of these string fields.Comment: 17 pages, to appear in JHE
Annulus Amplitudes and ZZ Branes in Minimal String Theory
We study the annulus amplitudes of (p,q) minimal string theory. Focusing on
the ZZ-FZZT annulus amplitude as a target-space probe of the ZZ brane, we use
it to confirm that the ZZ branes are localized in the strong-coupling region.
Along the way we learn that the ZZ-FZZT open strings are fermions, even though
our theory is bosonic! We also provide a geometrical interpretation of the
annulus amplitudes in terms of the Riemann surface M_{p,q} that emerges from
the FZZT branes. The ZZ-FZZT annulus amplitude measures the deformation of
M_{p,q} due to the presence of background ZZ branes; each kind of ZZ-brane
deforms only one A-period of the surface. Finally, we use the annulus
amplitudes to argue that the ZZ branes can be regarded as "wrong-branch"
tachyons which violate the bound \alpha<Q/2.Comment: 33 pages, new results in appendix, minor change
Closed String Tachyon Condensation at c=1
The c=1 matrix model, with or without a type 0 hat, has an exact quantum
solution corresponding to closed string tachyon condensation along a null
surface. The condensation occurs, and spacetime dissolves, at a finite retarded
time on I^+. The outgoing quantum state of tachyon fluctuations in this
time-dependent background is computed using both the collective field and exact
fermion pictures. Perturbative particle production induced by the moving
tachyon wall is shown to be similar to that induced by a soft moving mirror.
Hence, despite the fact that I^+ for the tachyon is geodesicaly incomplete,
quantum correlations in the incoming state are unitarily transmitted to the
outgoing state in perturbation theory. It is also shown that,
non-perturbatively, information can leak across the tachyon wall, and tachyon
scattering is not unitary. Exact unitarity remains intact only in the free
fermion picture.Comment: Minor corrections; References added; 24 pages, 2 figures, harvma
Universality of Nonperturbative Effects in c<1 Noncritical String Theory
Nonperturbative effects in c<1 noncritical string theory are studied using
the two-matrix model. Such effects are known to have the form fixed by the
string equations but the numerical coefficients have not been known so far.
Using the method proposed recently, we show that it is possible to determine
the coefficients for (p,q) string theory. We find that they are indeed finite
in the double scaling limit and universal in the sense that they do not depend
on the detailed structure of the potential of the two-matrix model.Comment: 17 page
Matrix Cosmology
Exact time-dependent solutions of c=1 string theory are described using the
free fermion formulation. One such class of solutions describes draining of the
Fermi sea and has a spacetime interpretation as closed string tachyon
condensation. A second class of solutions, corresponding to droplets of Fermi
liquid orbiting in phase space, describes closed cosmologies which bounce
through singularities.Comment: 21 pages, 6 figures, v2: added references, minor additions and
correction
Spacetime Properties of ZZ D-Branes
We study the tachyon and the RR field sourced by the ZZ D-branes in
type 0 theories using three methods. We first use the mini-superspace
approximation of the closed string wave functions of the tachyon and the RR
scalar to probe these fields. These wave functions are then extended beyond the
mini-superspace approximation using mild assumptions which are motivated by the
properties of the corresponding wave functions in the mini-superspace limit.
These are then used to probe the tachyon and the RR field sourced. Finally we
study the space time fields sourced by the ZZ D-branes using the FZZT
brane as a probe. In all the three methods we find that the tension of the
ZZ brane is times the tension of the ZZ brane. The RR
charge of these branes is non-zero only for the case of both and odd,
in which case it is identical to the charge of the brane. As a
consistency check we also verify that the space time fields sourced by the
branes satisfy the corresponding equations of motion.Comment: 32 pages, 4 figures. Clarifications on the principal characterization
of ZZ branes added. Reference adde
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