6,898 research outputs found
Type I background fields in terms of type IIB ones
We choose such boundary conditions for open IIB superstring theory which
preserve N=1 SUSY. The explicite solution of the boundary conditions yields
effective theory which is symmetric under world-sheet parity transformation
. We recognize effective theory as closed type I
superstring theory. Its background fields,beside known even fields of
the initial IIB theory, contain improvements quadratic in odd ones.Comment: 4 revtex pages, no figure
-brane type I superstring background fields in terms of type IIB ones by canonical method and T-duality approach
We consider type IIB superstring theory with embedded -brane and choose
boundary conditions which preserve half of the initial supersymmetry. In the
canonical approach that we use, boundary conditions are treated as canonical
constraints. The effective theory, obtained from the initial one on the
solution of boundary conditions, has the form of the type I superstring theory
with embedded -brane. We obtain the expressions for -brane background
fields of type I theory in terms of the -brane background fields of type
IIB theory. We show that beside known even fields, they contain
squares of odd ones, where is world-sheet parity
transformation, . We relate result of this paper and
the results of [1] using T-dualities along four directions orthogonal to
-brane
Noncommutativity relations in type IIB theory and their supersymmetry
In the present paper we investigate noncommutativity of and -brane
world-volumes embedded in space-time of type IIB superstring theory. Boundary
conditions, which preserve half of the initial supersymmetry, are treated as
canonical constraints. Solving the constraints we obtain original coordinates
in terms of the effective coordinates and momenta. Presence of momenta induces
noncommutativity of string endpoints. We show that noncommutativity relations
are connected by N=1 supersymmetry transformations and noncommutativity
parameters are components of N=1 supermultiplet
NeXSPheRIO results on elliptic flow at RHIC and connection with thermalization
Elliptic flow at RHIC is computed event-by-event with NeXSPheRIO. Reasonable
agreement with experimental results on is obtained. Various effects
are studied as well: reconstruction of impact parameter direction, freeze out
temperature, equation of state (with or without crossover), emission mecanism.Comment: Contribution to the Proceedings of the Quark-Gluon Plasma
Thermalization workshop. Content slightly increase
Lower-dimensional pure-spinor superstrings
We study to what extent it is possible to generalise Berkovits' pure-spinor
construction in d=10 to lower dimensions. Using a suitable definition of a
``pure'' spinor in d=4,6, we propose models analogous to the d=10 pure-spinor
superstring in these dimensions. Similar models in d=2,3 are also briefly
discussed.Comment: 17 page
An Introduction to the Covariant Quantization of Superstrings
We give an introduction to a new approach to the covariant quantization of
superstrings. After a brief review of the classical Green--Schwarz superstring
and Berkovits' approach to its quantization based on pure spinors, we discuss
our covariant formulation without pure spinor constraints. We discuss the
relation between the concept of grading, which we introduced to define vertex
operators, and homological perturbation theory, and we compare our work with
recent work by others. In the appendices, we include some background material
for the Green-Schwarz and Berkovits formulations, in order that this
presentation be self contained.Comment: LaTex, 23 pp. Contribution to the Proceedings of the Workshop in
String Theory, Leuven 2002, some references added and a comment on ref. [16
The Quantum Theory of Chern-Simons Supergravity
We consider -extended Chern-Simons supergravity (\`a la
Achucarro-Tonswend) and we study its gauge symmetries. We promote those gauge
symmetries to a BRST symmetry and we perform its quantization by choosing
suitable gauge-fixings. The resulting quantum theories have different features
which we discuss in the present work. In particular, we show that a special
choice of the gauge-fixing correctly reproduces the Ansatz by Alvarez,
Valenzuela and Zanelli for the graphene fermion.Comment: 25 pages. Some points clarified and conclusion section extended;
content of sections 3 and 4 reorganized. Version to be published on JHE
Large Firm Dynamics and the Business Cycle
Do large firm dynamics drive the business cycle? We answer this question by developing a quantitative theory of aggregate fluctuations caused by firm-level disturbances alone. We show that a standard heterogeneous firm dynamics setup already contains in it a theory of the business cycle, without appealing to aggregate shocks. We offer a complete analytical characterization of the law of motion of the aggregate state in this class of models – the firm size distribution – and show that the resulting closed form solutions for aggregate output and productivity dynamics display: (i) persistence, (ii) volatility and (iii) time-varying second moments. We explore the key role of moments of the firm size distribution – and, in particular, the role of large firm dynamics – in shaping aggregate fluctuations, theoretically, quantitatively and in the data
Effects of LatticeQCD EoS and Continuous Emission on Some ObseErvables
Effects of lattice-QCD-inspired equations of state and continuous emission on
some observables are discussed, by solving a 3D hydrodynamics. The particle
multiplicity as well as v2 are found to increase in the mid-rapidity. We also
discuss the effects of the initial-condition fluctuations.Comment: 6 pages, 10 figures, prepared for Workshop on Particle Correlations
and Fentoscopy, Kromeriz (Czech Republic), Aug. 15-17,200
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