scholarly journals Sigma model approach to string theory effective actions with tachyons

2001 ◽  
Vol 42 (7) ◽  
pp. 2854-2871 ◽  
Author(s):  
A. A. Tseytlin
Keyword(s):  
String Theory ◽  
Sigma Model ◽  
Model Approach

SIGMA MODEL APPROACH TO STRING THEORY

1989 ◽  
Vol 04 (06) ◽  
pp. 1257-1318 ◽  
Author(s):  
A.A. TSEYTLIN
Keyword(s):  
String Theory ◽  
Sigma Model ◽  
Equations Of Motion ◽  
Tree Approximation ◽  
Massless Fields ◽  
Model Approach

A review of the σ-model approach to derivation of effective string equations of motion for the massless fields is presented. We limit our consideration to the case of the tree approximation in the closed Bose string theory.

scholarly journals HADRONIC STRING, CONFORMAL INVARIANCE AND CHIRAL SYMMETRY

2003 ◽  
Vol 18 (14) ◽  
pp. 2501-2539 ◽  
Author(s):  
J. ALFARO ◽  
L. BALART ◽  
A. A. ANDRIANOV ◽  
D. ESPRIU
Keyword(s):  
String Theory ◽  
Sigma Model ◽  
Conformal Anomaly ◽  
Nonlinear Sigma Model ◽  
Leading Order ◽  
Qcd Vacuum ◽  
Fundamental String ◽  
Supersymmetric Version ◽  
Long Time ◽  
Model Approach

While it is clear that in some kinematic regime QCD can be described by an effective (as opposed to fundamental) string theory, it is not at all clear how this string theory should be. The "natural" candidate, the bosonic string, leads to amplitudes with the usual problems related to the existence of the tachyon, the absence of the adequate Adler zero, and massless vector particles, not to mention the conformal anomaly. The supersymmetric version does not really solve most of these problems. For a long time it has been believed that the solution of at least some of these difficulties is associated to a proper identification of the vacuum, but this program has remained elusive. We show in this work how the first three problems can be avoided, by using a sigma model approach where excitations above the correct (chirally noninvariant) QCD vacuum are identified. At the leading order in a derivative expansion we recover the nonlinear sigma model of pion interactions. At the next-to-leading order the O(p4) Lagrangian of Gasser and Leutwyler is obtained, with values for the coefficients that match the observed values. We also discuss some issues related to the conformal anomaly.

scholarly journals Superfield Hamiltonian quantization in terms of quantum antibrackets

2016 ◽  
Vol 31 (11) ◽  
pp. 1650054 ◽  
Author(s):  
Igor A. Batalin ◽  
Peter M. Lavrov
Keyword(s):  
Sigma Model ◽  
Equal Footing ◽  
Gauge Fixing ◽  
Actual Use ◽  
New Feature ◽  
Hamiltonian Quantization ◽  
Model Approach

We develop a new version of the superfield Hamiltonian quantization. The main new feature is that the BRST-BFV charge and the gauge fixing Fermion are introduced on equal footing within the sigma model approach, which provides for the actual use of the quantum/derived antibrackets. We study in detail the generating equations for the quantum antibrackets and their primed counterparts. We discuss the finite quantum anticanonical transformations generated by the quantum antibracket.

scholarly journals THE SIGMA MODEL FORMULATION OF TYPE II STRING THEORY IN THE AdS5 × S5 BACKGROUNDS WITH RAMOND–RAMOND FLUX

2003 ◽  
Vol 18 (10) ◽  
pp. 1749-1760
Author(s):  
SATCHIDANANDA NAIK
Keyword(s):  
String Theory ◽  
Sigma Model ◽  
Type Ii ◽  
Model Formulation ◽  
Model Action

A sigma model action is constructed for the type II string in the AdS 5 × S5 backgrounds with Ramond–Ramond flux.

scholarly journals DILATONIC GRAVITY NEAR TWO DIMENSIONS AS A STRING THEORY

1995 ◽  
Vol 10 (27) ◽  
pp. 2001-2008 ◽  
Author(s):  
E. ELIZALDE ◽  
S.D. ODINTSOV
Keyword(s):  
Fixed Point ◽  
Renormalization Group ◽  
String Theory ◽  
Sigma Model ◽  
Scalar Fields ◽  
Two Dimensions ◽  
Gravitational Coupling ◽  
Dilaton Coupling

Using the renormalization group formalism, a sigma model of a special type — in which the metric and the dilaton depend explicitly on one of the string coordinates only — is investigated near two dimensions. It is seen that dilatonic gravity coupled to N scalar fields can be expressed in this form, using a string parametrization, and that it possesses the usual uv fixed point. However, in this stringy parametrization of the theory the fixed point for the scalar-dilaton coupling turns out to be trivial, while that for the gravitational coupling remains the same as in previous studies being, in particular, nontrivial.

scholarly journals N = 4: a unifying framework for 2d topological gravity, cM ≤ 1 string theory and constrained topological sigma model

1995 ◽  
Vol 352 (3-4) ◽  
pp. 254-260 ◽  
Author(s):  
Pablo M Llatas ◽  
Shibaji Roy ◽  
J.M Sanchez de Santos
Keyword(s):  
String Theory ◽  
Sigma Model ◽  
Topological Gravity
Sign in / Sign up

Export Citation Format

Share Document