Results 1  10
of
12
Symmetry Breaking Boundary States and Defect Lines
, 2008
"... We present a large and universal class of new boundary states which break part of the chiral symmetry in the underlying bulk theory. Our formulas are based on coset constructions and they can be regarded as a nonabelian generalization of the ideas that were used by Maldacena, Moore and Seiberg to b ..."
Abstract

Cited by 55 (9 self)
 Add to MetaCart
We present a large and universal class of new boundary states which break part of the chiral symmetry in the underlying bulk theory. Our formulas are based on coset constructions and they can be regarded as a nonabelian generalization of the ideas that were used by Maldacena, Moore and Seiberg to build new boundary states for SU(N). We apply our expressions to construct defect lines joining two conformal field theories with possibly different central charge. Such defects can occur e.g. in the AdS/CFT correspondence when branes extend to the boundary of the AdSspace.
Open strings
 Phys.Rep. 371 (2002), 1–150 [hepth/ 0204089] [ibid. 376 (2003) 339, Erratum
"... Abstract. This review is devoted to open strings, and in particular to the often surprising features of their spectra. It follows and summarizes developments that took place mainly at the University of Rome “Tor Vergata ” over the last decade, and centred on worldsheet aspects of the constructions ..."
Abstract

Cited by 12 (0 self)
 Add to MetaCart
(Show Context)
Abstract. This review is devoted to open strings, and in particular to the often surprising features of their spectra. It follows and summarizes developments that took place mainly at the University of Rome “Tor Vergata ” over the last decade, and centred on worldsheet aspects of the constructions now commonly referred to as “orientifolds”. Our presentation aims to bridge the gap between the worldsheet analysis, that first exhibited many of the novel features of these systems, and their geometric description in terms of extended objects, Dbranes and Oplanes, contributed by many other colleagues, and most notably by J. Polchinski. We therefore proceed through a number of prototype examples, starting from the bosonic string and moving on to tendimensional fermionic strings and their toroidal and orbifold compactifications, in an attempt to guide the reader in a selfcontained journey to the more recent developments related to the breaking of supersymmetry. PACS numbers: 11.25.w,11.25.Db,11.25.Hf,11.25.Mj
WZW branes and gerbes
"... We reconsider the role that bundle gerbes play in the formulation of the WZW model on closed and open surfaces. In particular, we show how an analysis of bundle gerbes on groups covered by SU(N) permits to determine the spectrum of symmetric branes in the boundary version of the WZW model with such ..."
Abstract

Cited by 11 (1 self)
 Add to MetaCart
(Show Context)
We reconsider the role that bundle gerbes play in the formulation of the WZW model on closed and open surfaces. In particular, we show how an analysis of bundle gerbes on groups covered by SU(N) permits to determine the spectrum of symmetric branes in the boundary version of the WZW model with such groups as the target. We also describe a simple relation between the open string amplitudes in the WZW models based on simply connected groups and in their simplecurrent orbifolds. 1
Rolling Tachyon in Antide Sitter Spacetime
, 2006
"... We study the decay of the unstable Dparticle in threedimensional antide Sitter spacetime using worldsheet boundary conformal field theory methods. We test the open string completeness conjecture in a background for which the phase space available is only fieldtheoretic. This could present a ser ..."
Abstract

Cited by 4 (1 self)
 Add to MetaCart
(Show Context)
We study the decay of the unstable Dparticle in threedimensional antide Sitter spacetime using worldsheet boundary conformal field theory methods. We test the open string completeness conjecture in a background for which the phase space available is only fieldtheoretic. This could present a serious challenge to the claim. We compute the emission of closed strings in the AdS3 × S3 × T4 background from the knowledge of the exact corresponding boundary state we construct. We show that the energy stored in the brane is mainly converted into very excited long strings. The energy stored in short strings and in open string pair production is much smaller and finite for any value of the string coupling. We find no ”missing energy ” problem. We compare our results to those obtained for a decay in flat spacetime and to a background in the presence of a linear dilaton. Some remarks on holographic aspects of the problem are made. 1 Introduction and summary Understanding the physics of timedependent backgrounds is one of the the greatest challenges in string theory. It is important for the understanding of basic issues in quantum gravity and for
Dbranes and orientifolds of SO(3
 JHEP
, 2002
"... Abstract: We study branes and orientifolds on the group manifold of SO(3). We consider particularly the case of the equatorial branes, which are projective planes. We show that a DiracBornInfeld action can be defined on them, although they are not orientable. We find that there are two orientifold ..."
Abstract

Cited by 3 (1 self)
 Add to MetaCart
(Show Context)
Abstract: We study branes and orientifolds on the group manifold of SO(3). We consider particularly the case of the equatorial branes, which are projective planes. We show that a DiracBornInfeld action can be defined on them, although they are not orientable. We find that there are two orientifold projections with the same spacetime action, which differ by their action on equatorial branes.
Dbrane charges on SO(3)
, 2005
"... In this letter we discuss charges of Dbranes on the group manifold SO(3). Our discussion will be based on a conformal field theory analysis of boundary states in a Z2orbifold of SU(2). This orbifold differs from the one recently discussed by Gaberdiel and Gannon in its action on the fermions and l ..."
Abstract

Cited by 3 (0 self)
 Add to MetaCart
In this letter we discuss charges of Dbranes on the group manifold SO(3). Our discussion will be based on a conformal field theory analysis of boundary states in a Z2orbifold of SU(2). This orbifold differs from the one recently discussed by Gaberdiel and Gannon in its action on the fermions and leads to a drastically different charge group. We shall consider maximally symmetric branes as well as branes with less symmetry, and find perfect agreement with a recent computation of the corresponding Ktheory groups.
Lectures on Branes in Curved Backgrounds
 LECTURES PRESENTED AT THE THIRD RTN SCHOOL ON ‘THE QUANTUM STRUCTURE OF SPACETIME
, 2002
"... These lectures provide an introduction to the microscopic description of branes in curved backgrounds. After a brief reminder of the flat space theory, the basic principles and techniques of (rational) boundary conformal field theory are presented in the second lecture. The general formalism is then ..."
Abstract
 Add to MetaCart
(Show Context)
These lectures provide an introduction to the microscopic description of branes in curved backgrounds. After a brief reminder of the flat space theory, the basic principles and techniques of (rational) boundary conformal field theory are presented in the second lecture. The general formalism is then illustrated through a detailed discussion of branes on compact group manifolds. In the final lecture, many more recent developments are reviewed, including some results for noncompact target spaces.
hepth/0403011 Dbrane charges on nonsimply connected groups
, 2004
"... The maximally symmetric Dbranes of string theory on the nonsimply connected Lie group SU(n)/Zd are analysed using conformal field theory methods, and their charges are determined. Unlike the well understood case for simply connected groups, the charge equations do not determine the charges uniquel ..."
Abstract
 Add to MetaCart
(Show Context)
The maximally symmetric Dbranes of string theory on the nonsimply connected Lie group SU(n)/Zd are analysed using conformal field theory methods, and their charges are determined. Unlike the well understood case for simply connected groups, the charge equations do not determine the charges uniquely, and the charge group associated to these Dbranes is therefore in general not cyclic. The precise structure of the charge group depends on some number theoretic properties of n, d, and the level of the underlying affine algebra k. The examples of SO(3) =SU(2)/Z2 and SU(3)/Z3 are worked out in detail, and the charge groups for SU(n)/Zd at most levels k are determined explicitly.
Boundary States of c = 1 and 3/2 Rational Conformal Field Theories
, 2002
"... We study the boundary states for the rational points in the moduli spaces of c = 1 conformal and c = 3/2 superconformal field theories, including the isolated Ginsparg points. We use the orbifold and simplecurrent techniques to relate the boundary states of different theories and to obtain symmetry ..."
Abstract
 Add to MetaCart
(Show Context)
We study the boundary states for the rational points in the moduli spaces of c = 1 conformal and c = 3/2 superconformal field theories, including the isolated Ginsparg points. We use the orbifold and simplecurrent techniques to relate the boundary states of different theories and to obtain symmetrybreaking, nonCardy boundary states. We show some interesting examples of One of the topics of present string theory investigations is the determination of Dbranes on general backgrounds: their algebraic construction as boundary states of conformal field theory, their classification, the relevant consistency conditions and their geometrical interpretation [1][2][3][4][5].
hepth/0403011 Dbrane charges on nonsimply connected groups
, 2004
"... The maximally symmetric Dbranes of string theory on the nonsimply connected Lie group SU(n)/Zd are analysed using conformal field theory methods, and their charges are determined. Unlike the well understood case for simply connected groups, the charge equations do not determine the charges uniquel ..."
Abstract
 Add to MetaCart
(Show Context)
The maximally symmetric Dbranes of string theory on the nonsimply connected Lie group SU(n)/Zd are analysed using conformal field theory methods, and their charges are determined. Unlike the well understood case for simply connected groups, the charge equations do not determine the charges uniquely, and the charge group associated to these Dbranes is therefore in general not cyclic. The precise structure of the charge group depends on some number theoretic properties of n, d, and the level of the underlying affine algebra k. The examples of SO(3) =SU(2)/Z2 and SU(3)/Z3 are worked out in detail, and the charge groups for SU(n)/Zd at most levels k are determined explicitly.