scholarly journals GENERALIZED W3-STRINGS FROM FREE FIELDS

1995 ◽  
Vol 10 (06) ◽  
pp. 515-524 ◽  
Author(s):  
J. M. FIGUEROA-O'FARRILL ◽  
C. M. HULL ◽  
L. PALACIOS ◽  
E. RAMOS
Keyword(s):  
Bosonic Strings ◽  
Free Field ◽  
Space Time ◽  
General Construction ◽  
Special Cases ◽  
Free Fields ◽  
Rule Out ◽  
General Conditions ◽  
String Theories

The conventional quantization of w3-strings gives theories which are equivalent to special cases of bosonic strings. We explore whether a more general quantization can lead to new generalized W3-string theories by seeking to construct quantum BRST charges directly without requiring the existence of a quantum W3-algebra. We study W3-like strings with a direct space-time interpretation — that is, with matter given by explicit free field realizations. Special emphasis is placed on the attempt to construct a quantum W-string associated with the magic realizations of the classical w3-algebra. We give the general conditions for the existence of W3-like strings, and comment on how the known results fit into our general construction. Our results are negative: we find no new consistent string theories, and in particular rule out the possibility of critical strings based on the magic realizations.

SPECTRAL FLOW AND FREE FIELD REALIZATIONS OF BOSONIC STRINGS ON NAPPI–WITTEN GROUP MANIFOLD

2011 ◽  
Vol 26 (01) ◽  
pp. 149-160
Author(s):  
GANG CHEN
Keyword(s):  
Lie Algebra ◽  
Bosonic Strings ◽  
Free Field ◽  
Geometric Interpretation ◽  
Closed String ◽  
Space Time ◽  
Spectral Flow ◽  
Affine Lie Algebra ◽  
Group Manifold ◽  
Free Field Realization

In this paper we study some aspects of closed string theories in the Nappi–Witten space–time. The effects of spectral flow on the geodesics are studied in terms of an explicit parametrization of the group manifold. The worldsheets of the closed strings under the spectral flow of the geodesics can be classified into four classes, each with a geometric interpretation. We also obtain a free field realization of the Nappi–Witten affine Lie algebra in the most general conditions using a different but equivalent parametrization of the group manifold.

scholarly journals BRANE SOLUTIONS IN TIME-DEPENDENT BACKGROUNDS IN D = 11 SUPERGRAVITY AND IN TYPE II STRING THEORIES

2008 ◽  
Vol 23 (16n17) ◽  
pp. 2525-2540 ◽  
Author(s):  
SRIKUMAR SEN GUPTA
Keyword(s):  
String Theory ◽  
Equations Of Motion ◽  
Space Time ◽  
Time Dependent ◽  
Type Ii ◽  
Reduced Equations ◽  
Special Cases ◽  
M Theory ◽  
String Theories

We obtain explicit time-dependent brane solutions in M-theory as well as in string theory by solving the reduced equations of motion (which follow, as in Int. J. Mod. Phys. A17, 4647 (2002), from 11-dimensional supergravity) for a class of brane solutions in curved backgrounds. The behavior of our solutions in both asymptotic and near-horizon limits are studied. It is shown that our time-dependent solutions serve as explicit examples of branes in singular, cosmological backgrounds. In some special cases the asymptotic and the boundary AdS solutions can be identified as Milne × Rn space–time.

scholarly journals Triangles of Baumslag–Solitar Groups

2012 ◽  
Vol 64 (2) ◽  
pp. 241-253 ◽  
Author(s):  
Daniel Allcock
Keyword(s):  
Finite Groups ◽  
Derived Length ◽  
Special Cases ◽  
Finite Quotients ◽  
General Conditions

Abstract Our main result is that many triangles of Baumslag–Solitar groups collapse to finite groups, generalizing a famous example of Hirsch and other examples due to several authors. A triangle of Baumslag–Solitar groups means a group with three generators, cyclically ordered, with each generator conjugating some power of the previous one to another power. There are six parameters, occurring in pairs, and we show that the triangle fails to be developable whenever one of the parameters divides its partner, except for a few special cases. Furthermore, under fairly general conditions, the group turns out to be finite and solvable of derived length ≤ 3. We obtain a lot of information about finite quotients, even when we cannot determine developability.

Free Quantum Fields

2020 ◽  
pp. 247-260
Author(s):  
Daniel Canarutto
Keyword(s):  
Free Field ◽  
Gauge Fields ◽  
Quantum Field ◽  
Quantum Fields ◽  
Dirac Fields ◽  
Free Fields ◽  
Explicit Expressions

The notion of free quantum field is thoroughly discussed in the linearised setting associated with the choice of a detector. The discussion requires attention to certain details that are often overlooked in the standard literature. Explicit expressions for generic fields, Dirac fields, gauge fields and ghost fields are laid down, as well the ensuing free-field expressions of important functionals. The relations between super-commutators of free fields and propagators, and the canonical super-commutation rules, follow from the above results.

10. Visitors: entry for temporary purposes

2018 ◽  
Author(s):  
Gina Clayton ◽  
Georgina Firth ◽  
Caroline Sawyer ◽  
Rowena Moffatt ◽  
Helena Wray
Keyword(s):  
Medical Treatment ◽  
Family Members ◽  
Short Term ◽  
Special Cases ◽  
The Law ◽  
The Uk ◽  
General Conditions

Course-focused and comprehensive, the Textbook on series provides an accessible overview of the key areas on the law curriculum. This chapter discusses the law relating to individuals coming to the UK as visitors for short-term or finite purposes such as tourism, business visits, sporting and entertainment engagements, or for private medical treatment. There is a discussion of the withdrawal, reinstatement, and restriction of rights of appeal for those visiting family members in the UK, and the application of Article 8 ECHR to these situations. The revised visitor rules in Appendix V are described in detail. The chapter also discusses the special cases of marriage visitors, carers and transit visitors, and general conditions such as prohibited activities and the need for maintenance and accommodation.

On the general correspondence between field theories and the theories of direct interparticle action

1968 ◽  
Vol 64 (4) ◽  
pp. 1071-1079 ◽  
Author(s):  
J. V. Narlikar
Keyword(s):  
Field Theory ◽  
General Relativity ◽  
Riemannian Space ◽  
Arbitrary Spin ◽  
Space Time ◽  
Field Theories ◽  
Classical Electrodynamics ◽  
General Correspondence ◽  
General Conditions

AbstractIt is well known that classical electrodynamics can be described both as a field theory and as a theory of direct interparticle action. In the present paper it is shown that, provided certain general conditions are satisfied, fields of arbitrary spin have their counterparts in ‘direct particle fields’. This correspondence between the two formalisms is established in the Riemannian space-time used for general relativity.

scholarly journals EXTRA DIMENSIONS AND POSSIBLE SPACE-TIME SIGNATURE CHANGES

1995 ◽  
Vol 04 (04) ◽  
pp. 491-516 ◽  
Author(s):  
K.A. BRONNIKOV
Keyword(s):  
Black Hole ◽  
Extra Dimensions ◽  
Field Potential ◽  
Space Time ◽  
Spherically Symmetric ◽  
Vector Coupling ◽  
Special Cases ◽  
Dimensional Gravity ◽  
Time Changes ◽  
A Chain

Exact static, spherically symmetric solutions to the Einstein-Maxwell-scalar equations, with a dilatonic-type scalar-vector coupling, in D-dimensional gravity with a chain of n Ricci-flat internal spaces are considered, with the Maxwell field potential having two nonzero components: the temporal, Coulomb-like one and the one pointing to one of the extra dimensions. The properties and special cases of the solutions are discussed, in particular, those when there are horizons in the space-time. Two types of horizons are distinguished: the conventional black-hole (BH) ones and those at which the physical section of the space-time changes its signature (the latter are called T-horizons). Two theorems are proved, one fixing the BH- and T-horizon existence conditions, the other claiming that the system under study cannot have a regular center. The stability of a selected family of solutions under spherically symmetric perturbations is studied. It is shown that only black-hole solutions are stable, while all others, in particular, those with T-horizons are unstable.

scholarly journals Space/Time Noncommutativity in String Theories without Background Electric Field

2002 ◽  
Vol 2002 (12) ◽  
pp. 031-031 ◽  
Author(s):  
Giuseppe De Risi ◽  
Gianluca Grignani ◽  
Marta Orselli
Keyword(s):  
Electric Field ◽  
Space Time ◽  
String Theories

Causal amplitudes and the Yang-Feldman formalism

1957 ◽  
Vol 53 (4) ◽  
pp. 843-847 ◽  
Author(s):  
J. C. Polkinghorne
Keyword(s):  
Field Theory ◽  
Green’S Functions ◽  
Free Field ◽  
Dispersion Relations ◽  
Matrix Elements ◽  
Field Equations ◽  
Commutation Relations ◽  
The Matrix ◽  
Free Fields ◽  
Set Up

ABSTRACTThe Yang-Feldman formalism vising the Feynman-like Green's functions is set up. The corresponding free fields have non-trivial commutation relations and contain information about the scattering. S-matrix elements are simply the matrix elements of anti-normal products of the field φF′(x). These are evaluated, and they give directly expressions used in the theory of causality and dispersion relations. It is possible to formulate field theory in a form in which the fields obey free field equations and the effects of interaction are contained in their commutation relations.

Sign in / Sign up

Export Citation Format

Share Document