scholarly journals REFORMULATION OF BOUNDARY STRING FIELD THEORY IN TERMS OF BOUNDARY STATE

2008 ◽  
Vol 23 (14n15) ◽  
pp. 2281-2282
Author(s):  
SHUNSUKE TERAGUCHI
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
String Field Theory ◽  
International Workshop ◽  
Equations Of Motion ◽  
Target Space ◽  
Arbitrary Field ◽  
Quantum Field ◽  
Boundary State ◽  
Short Summary

We reformulate bosonic boundary string field theory in terms of boundary state. In our formulation, we can formally perform the integration of target space equations of motion for arbitrary field configurations without assuming decoupling of matter and ghost. This is a short summary of our contribution to the international workshop "Progress of String Theory and Quantum Field Theory" at Osaka City University (December 7-10, 2007).

scholarly journals Exploring the thermodynamics of noncommutative scalar fields

2016 ◽  
Vol 31 (11) ◽  
pp. 1650057 ◽  
Author(s):  
Francisco A. Brito ◽  
Elisama E. M. Lima
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Thermodynamic Properties ◽  
Scalar Fields ◽  
Einstein Condensate ◽  
Target Space ◽  
Quantum Field ◽  
Condensate Fraction ◽  
Bose Einstein Condensate ◽  
Bose Einstein

We study the thermodynamic properties of the Bose–Einstein condensate (BEC) in the context of the quantum field theory with noncommutative target space. Our main goal is to investigate in which temperature and/or energy regimes the noncommutativity can characterize some influence on the BEC properties described by a relativistic massive noncommutative boson gas. The noncommutativity parameters play a key role in the modified dispersion relations of the noncommutative fields, leading to a new phenomenology. We have obtained the condensate fraction, internal energy, pressure and specific heat of the system and taken ultrarelativistic (UR) and nonrelativistic (NR) limits. The noncommutative effects on the thermodynamic properties of the system are discussed. We found that there appear interesting signatures around the critical temperature.

scholarly journals DUALITY OF STRING AMPLITUDES IN A CURVED BACKGROUND

1993 ◽  
Vol 08 (30) ◽  
pp. 5409-5440
Author(s):  
MÅNS HENNINGSON
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Scattering Amplitudes ◽  
String Theory ◽  
Target Space ◽  
Quantum Field ◽  
Group Manifold ◽  
String Amplitudes ◽  
Theory Calculation ◽  
The Relationship

We initiate a program to study the relationship between the target space, the spectrum and the scattering amplitudes in string theory. We consider scattering amplitudes following from string theory and quantum field theory on a curved target space, which is taken to be the SU(2) group manifold, with special attention given to the duality between contributions from different channels. We give a simple example of the equivalence between amplitudes coming from string theory and quantum field theory, and compute the general form of a four-scalar field-theoretical amplitude. The corresponding string theory calculation is performed for a special case, and we discuss how more general string theory amplitudes could be evaluated.

scholarly journals STRING FIELD THEORY FROM QUANTUM GRAVITY

2013 ◽  
Vol 25 (10) ◽  
pp. 1343005
Author(s):  
LOUIS CRANE
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Standard Model ◽  
Quantum Gravity ◽  
String Field Theory ◽  
Neutrino Oscillations ◽  
Coupled Model ◽  
Dual Model ◽  
Quantum Field ◽  
The Standard Model

Recent work on neutrino oscillations suggests that the three generations of fermions in the standard model are related by representations of the finite group A(4), the group of symmetries of the tetrahedron. Motivated by this, we explore models which extend the EPRL model for quantum gravity by coupling it to a bosonic quantum field of representations of A(4). This coupling is possible because the representation category of A(4) is a module category over the representation categories used to construct the EPRL model. The vertex operators which interchange vacua in the resulting quantum field theory reproduce the bosons and fermions of the standard model, up to issues of symmetry breaking which we do not resolve. We are led to the hypothesis that physical particles in nature represent vacuum changing operators on a sea of invisible excitations which are only observable in the A(4) representation labels which govern the horizontal symmetry revealed in neutrino oscillations. The quantum field theory of the A(4) representations is just the dual model on the extended lattice of the Lie group E6, as explained by the quantum McKay correspondence of Frenkel, Jing and Wang. The coupled model can be thought of as string field theory, but propagating on a discretized quantum spacetime rather than a classical manifold.

scholarly journals Classical instanton solutions in quantum field theory

2020 ◽  
pp. 78-85
Author(s):  
Roman G. Shulyakovsky ◽  
Alexander S. Gribowsky ◽  
Alexander S. Garkun ◽  
Maxim N. Nevmerzhitsky ◽  
Alexei O. Shaplov ◽  
...  
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Quantum Theory ◽  
Yukawa Potential ◽  
Equations Of Motion ◽  
Two Dimensions ◽  
Quantum Field ◽  
Two Dimensional ◽  
Yang Mills ◽  
The One

Instantons are non-trivial solutions of classical Euclidean equations of motion with a finite action. They provide stationary phase points in the path integral for tunnel amplitude between two topologically distinct vacua. It make them useful in many applications of quantum theory, especially for describing the wave function of systems with a degenerate vacua in the framework of the path integrals formalism. Our goal is to introduce the current situation about research on instantons and prepare for experiments. In this paper we give a review of instanton effects in quantum theory. We find in stanton solutions in some quantum mechanical problems, namely, in the problems of the one-dimensional motion of a particle in two-well and periodic potentials. We describe known instantons in quantum field theory that arise, in particular, in the two-dimensional Abelian Higgs model and in SU(2) Yang – Mills gauge fields. We find instanton solutions of two-dimensional scalar field models with sine-Gordon and double-well potentials in a limited spatial volume. We show that accounting of instantons significantly changes the form of the Yukawa potential for the sine-Gordon model in two dimensions.

Simulating Equilibrium Behavior of Quantum Fields with Time-evolving Classical Fields

2021 ◽  
Vol 1 ◽  
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Real Time ◽  
Time Evolution ◽  
Equations Of Motion ◽  
Quantum Field ◽  
Quantum Fields ◽  
Equilibrium Behavior ◽  
Classical Fields

A set of field configurations (replicas) reaches equilibrium of quantum field theory after real-time evolution obeying classical equations of motion.

On the Feynman principle

1955 ◽  
Vol 230 (1181) ◽  
pp. 272-276 ◽  
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Equations Of Motion ◽  
Canonical Formalism ◽  
Quantum Field ◽  
Usual Definition ◽  
Canonical Commutation Relations ◽  
Commutation Relations ◽  
Feynman Amplitudes ◽  
Definition Of

The formulation of quantum field theory in terms of the Feynman principle is discussed. It is shown that the operators defined in terms of this principle satisfy the equations of motion. A definition of canonically conjugate momenta is given in terms of the principle and is shown to be equivalent to the usual definition. The canonical commutation relations are then deduced and the equivalence of this formulation and the canonical formalism is thereby established. The equations for Feynman amplitudes are also obtained. In conclusion some difficulties of the theory and some possible extensions are discussed.

scholarly journals Conformal defects from string field theory

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Kasia Budzik ◽  
Miroslav Rapčák ◽  
Jairo M. Rojas
Keyword(s):  
Field Theory ◽  
String Field Theory ◽  
Topological Defect ◽  
Equations Of Motion ◽  
Open String ◽  
Minimal Models ◽  
Model Case ◽  
Conformal Boundary ◽  
Boundary State ◽  
Space Approach

Abstract Unlike conformal boundary conditions, conformal defects of Virasoro minimal models lack classification. Alternatively to the defect perturbation theory and the truncated conformal space approach, we employ open string field theory (OSFT) techniques to explore the space of conformal defects. We illustrate the method by an analysis of OSFT around the background associated to the (1, 2) topological defect in diagonal unitary minimal models. Numerical analysis of OSFT equations of motion leads to an identification of a nice family of solutions, recovering the picture of infrared fixed points due to Kormos, Runkel and Watts. In particular, we find a continuum of solutions in the Ising model case and 6 solutions for other minimal models. OSFT provides us with numerical estimates of the g-function and other coefficients of the boundary state.

scholarly journals METHODS FOR THE ANALYSIS OF THE LINDSTEDT SERIES FOR KAM TORI AND RENORMALIZABILITY IN CLASSICAL MECHANICS: A review with Some Applications

1996 ◽  
Vol 08 (03) ◽  
pp. 393-444 ◽  
Author(s):  
G. GENTILE ◽  
V. MASTROPIETRO
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Formal Solution ◽  
Equations Of Motion ◽  
Classical Mechanics ◽  
Hamiltonian Function ◽  
Quantum Field ◽  
Kam Theorem ◽  
Renormalization Group Approach ◽  
Lindstedt Series

This paper consists in a unified exposition of methods and techniques of the renormalization group approach to quantum field theory applied to classical mechanics, and in a review of results: (1) a proof of the KAM theorem, by studying the perturbative expansion (Lindstedt series) for the formal solution of the equations of motion; (2) a proof of a conjecture by Gallavotti about the renormalizability of isochronous hamiltonians, i.e. the possibility to add a term depending only on the actions in a hamiltonian function not verifying the anisochrony condition so that the resulting hamiltonian is integrable. Such results were obtained first by Eliasson; however the difficulties arising in the study of the perturbative series are very similar to the problems which one has to deal with in quantum field theory, so that the use of the methods which have been envisaged and developed in the last twenty years precisely in order to solve them allows us to obtain unified proofs, both conceptually and technically. In the final part of the review, the original work of Eliasson is analyzed and exposed in detail; its connection with other proofs of the KAM theorem based on his method is elucidated.

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