887 research outputs found
Curvature formula for the space of 2-d conformal field theories
We derive a formula for the curvature tensor of the natural Riemannian metric
on the space of two-dimensional conformal field theories and also a formula for
the curvature tensor of the space of boundary conformal field theories.Comment: 36 pages, 1 figure; v2 references adde
BRST Invariant Higher Derivative Operators in 4D Quantum Gravity based on CFT
We continue the study of physical fields for the background free 4D quantum
gravity based on the Riegert-Wess-Zumino action, developed in Phys. Rev. D {\bf
85} (2012) 024028. The background free model is formulated in terms of a
certain conformal field theory on M^4 in which conformal symmetry arises as
gauge symmetry, namely diffeomorphism invariance. In this paper, we construct
the physical field operator corresponding to any integer power of Ricci scalar
curvature in the context of the BRST quantization. We also discuss how to
define the correlation function and its physical meanings.Comment: 22 pages, minor typo corrected, published versio
SYM, Chern-Simons, Wess-Zumino Couplings and their higher derivative corrections in IIA Superstring theory
We find the entire form of the amplitude of two fermion strings (with
different chirality), a massless scalar field and one closed string
Ramond-Ramond (RR) in IIA superstring theory which is different from its IIB
one. We make use of a very particular gauge fixing and explore several new
couplings in IIA. All infinite - channel scalar poles and - channel
fermion poles are also constructed. We find new form of higher derivative
corrections to two fermion two scalar couplings and show that the first simple
channel scalar pole for case can be obtained by having new
higher derivative corrections to SYM couplings at third order of . We
find that the general structure and the coefficients of higher derivative
corrections to two fermion two scalar couplings are completely different from
the derived higher derivative corrections of type IIB.Comment: 29 pages, no figure,Latex file,published version in EPJ
Non-Relativistic Superstring Theories
We construct a supersymmetric version of the ``critical'' non-relativistic
bosonic string theory\cite{Kim:2007hb} with its manifest global symmetry. We
introduce the anticommuting CFT which is the super partner of the
CFT. The conformal weights of the and fields are both
1/2. The action of the fermionic sector can be transformed into that of the
relativistic superstring theory. We explicitly quantize the theory with
manifest SO(8) symmetry and find that the spectrum is similar to that of Type
IIB superstring theory. There is one notable difference: the fermions are
non-chiral. We further consider ``noncritical'' generalizations of the
supersymmetric theory using the superspace formulation. There is an infinite
range of possible string theories similar to the supercritical string theories.
We comment on the connection between the critical non-relativistic string
theory and the lightlike Linear Dilaton theory.Comment: Typos corrected, references added. A version to appear in Phys. Rev.
On the Boundary Entropy of One-dimensional Quantum Systems at Low Temperature
The boundary beta-function generates the renormalization group acting on the
universality classes of one-dimensional quantum systems with boundary which are
critical in the bulk but not critical at the boundary. We prove a gradient
formula for the boundary beta-function, expressing it as the gradient of the
boundary entropy s at fixed non-zero temperature. The gradient formula implies
that s decreases under renormalization except at critical points (where it
stays constant). At a critical point, the number exp(s) is the ``ground-state
degeneracy,'' g, of Affleck and Ludwig, so we have proved their long-standing
conjecture that g decreases under renormalization, from critical point to
critical point. The gradient formula also implies that s decreases with
temperature except at critical points, where it is independent of temperature.
The boundary thermodynamic energy u then also decreases with temperature. It
remains open whether the boundary entropy of a 1-d quantum system is always
bounded below. If s is bounded below, then u is also bounded below.Comment: 12 pages, Latex, 1 eps-figure; v2: some expository material added, a
slightly more condensed version of the paper is publihed in Phys. Rev. Let
BRST Properties of New Superstring States
Brane-like states are defined by physical vertex operators in NSR superstring
theory, existing at nonzero pictures only. These states exist both in open and
closed string theories, in the NS and NS-NS sectors respectively. In this paper
we present a detailed analysis of their BRST properties, giving a proof that
these vertex operators are physical, i.e. BRST invariant and BRST non-trivial.Comment: 25 pages, harvmac.te
Entropy flow in near-critical quantum circuits
Near-critical quantum circuits are ideal physical systems for asymptotically
large-scale quantum computers, because their low energy collective excitations
evolve reversibly, effectively isolated from the environment. The design of
reversible computers is constrained by the laws governing entropy flow within
the computer. In near-critical quantum circuits, entropy flows as a locally
conserved quantum current, obeying circuit laws analogous to the electric
circuit laws. The quantum entropy current is just the energy current divided by
the temperature. A quantum circuit made from a near-critical system (of
conventional type) is described by a relativistic 1+1 dimensional relativistic
quantum field theory on the circuit. The universal properties of the
energy-momentum tensor constrain the entropy flow characteristics of the
circuit components: the entropic conductivity of the quantum wires and the
entropic admittance of the quantum circuit junctions. For example,
near-critical quantum wires are always resistanceless inductors for entropy. A
universal formula is derived for the entropic conductivity:
\sigma_S(\omega)=iv^{2}S/\omega T, where \omega is the frequency, T the
temperature, S the equilibrium entropy density and v the velocity of `light'.
The thermal conductivity is Real(T\sigma_S(\omega))=\pi v^{2}S\delta(\omega).
The thermal Drude weight is, universally, v^{2}S. This gives a way to measure
the entropy density directly.Comment: 2005 paper published 2017 in Kadanoff memorial issue of J Stat Phys
with revisions for clarity following referee's suggestions, arguments and
results unchanged, cross-posting now to quant-ph, 27 page
Thirring Model with Non-conserved Chiral Charge
We study the Abelian Thirring Model when the fermionic fields have
non-conserved chiral charge: . One of the main features
we find for this model is the dependence of the Virasoro central charge on both
the Thirring coupling constant and . We show how to evaluate correlation
functions and in particular we compute the conformal dimensions for fermions
and fermionic bilinears, which depend on the fermionic chiral charge. Finally
we build primary fields with arbitrary conformal weight.Comment: pages 1
Two-dimensional topological gravity and equivariant cohomology
In this paper, we examine the analogy between topological string theory and
equivariant cohomology. We also show that the equivariant cohomology of a
topological conformal field theory carries a certain algebraic structure, which
we call a gravity algebra. (Error on page 9 corrected: BRS current contains
total derivatives.)Comment: 18 page
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