1,279 research outputs found
Simplifying and Extending the AdS_5xS^5 Pure Spinor Formalism
Although the AdS_5xS^5 worldsheet action is not quadratic, some features of
the pure spinor formalism are simpler in an AdS_5xS^5 background than in a flat
background. The BRST operator acts geometrically, the left and right-moving
pure spinor ghosts can be treated as complex conjugates, the zero mode measure
factor is trivial, and the b ghost does not require non-minimal fields.
Furthermore, a topological version of the AdS_5xS^5 action with the same
worldsheet variables and BRST operator can be constructed by gauge-fixing a G/G
principal chiral model where G=PSU(2,2|4). This topological model is argued to
describe the zero radius limit that is dual to free N=4 super-Yang-Mills and
can also be interpreted as an "unbroken phase" of superstring theory.Comment: 39 pages harvma
Pure Spinor Formalism as an N=2 Topological String
Following suggestions of Nekrasov and Siegel, a non-minimal set of fields are
added to the pure spinor formalism for the superstring. Twisted =3 N=2
generators are then constructed where the pure spinor BRST operator is the
fermionic spin-one generator, and the formalism is interpreted as a critical
topological string. Three applications of this topological string theory
include the super-Poincare covariant computation of multiloop superstring
amplitudes without picture-changing operators, the construction of a cubic open
superstring field theory without contact-term problems, and a new
four-dimensional version of the pure spinor formalism which computes F-terms in
the spacetime action.Comment: 34 pages harvmac te
BRST quantization of the pure spinor superstring
We present a derivation of the scattering amplitude prescription for the pure
spinor superstring from first principles, both in the minimal and non-minimal
formulations, and show that they are equivalent. This is achieved by first
coupling the worldsheet action to topological gravity and then proceeding to
BRST quantize this system. Our analysis includes the introduction of constant
ghosts and associated auxiliary fields needed to gauge fix symmetries
associated with zero modes. All fields introduced in the process of
quantization can be integrated out explicitly, resulting in the prescriptions
for computing scattering amplitudes that have appeared previously in the
literature. The zero mode insertions in the path integral follow from the
integration over the constant auxiliary fields.Comment: 31 page
Supersymmetric Born-Infeld from the Pure Spinor Formalism of the Open Superstring
Classical BRST invariance in the pure spinor formalism for the open
superstring is shown to imply the supersymmetric Born-Infeld equations of
motion for the background fields. These equations are obtained by requiring
that the left and right-moving BRST currents are equal on the worldsheet
boundary in the presence of the background. The Born-Infeld equations are
expressed in N=1 D=10 superspace and include all abelian contributions to the
low-energy equations of motion, as well as the leading non-abelian
contributions.Comment: Added footnote 3 in agreement with the comments of Schiappa and
Wyllard in hep-th/050312
Creep of AU-4G1 aluminum alloy under incremental variation in stress Final report
Linear viscoelastic analysis of incremental load test data on AU-4G1 aluminum alloy sheet subjected to tensile creep at 473 deg
Estimation of high temperature low cycle fatigue on the basis of inelastic strain and strainrate
Fatigue life at elevated temperature can be predicted by introducing parametric values obtained from monotonic constitutive behavior into the Universal-Slopes Equation. For directionally solidified MAR-M200+HF at 975 C, these parameters are the maximum stress achievable under entirely plastic (time-independent) and purely creep (time-dependent) conditions and the corresponding inelastic strains, as well as the elastic modulus. For materials which exhibit plasticity/creep interaction, two more pairs of monotonic parameters must be evaluated for fatigue life prediction. This life-prediction method based on the Universal-Slopes Equation, resulted from a constitutive model characterizing monotonic and cyclic data as inelastic strainrate as a function of inelastic strain. Characterizing monotonic data is this way, permitted distinction between different material responses such as strain-hardening, strain-softening, and dynamic recovery effects. Understanding and defining the region of influence of each of these effects facilitated formulation of the constitutive model in relation to the mechanical and microstructural processes occurring in the material under cyclic loading
Non-BPS D-Branes in Light-Cone Green-Schwarz Formalism
Non-BPS D-branes are difficult to describe covariantly in a manifestly
supersymmetric formalism. For definiteness we concentrate on type IIB string
theory in flat background in light-cone Green-Schwarz formalism. We study both
the boundary state and the boundary conformal field theory descriptions of
these D-branes with manifest SO(8) covariance and go through various
consistency checks. We analyze Sen's original construction of non-BPS D-branes
given in terms of an orbifold boundary conformal field theory. We also directly
study the relevant world-sheet theory by deriving the open string boundary
condition from the covariant boundary state. Both these methods give the same
open string spectrum which is consistent with the boundary state, as required
by the world-sheet duality. The boundary condition found in the second method
is given in terms of bi-local fields that are quadratic in Green-Schwarz
fermions. We design a special ``doubling trick'' suitable to handle such
boundary conditions and prescribe rules for computing all possible correlation
functions without boundary insertions. This prescription has been tested by
computing disk one-point functions of several classes of closed string states
and comparing the results with the boundary state computation.Comment: 47 pages, 1 figure. Typos corrected, references added and slight
modification of certain explanation made. Version accepted for publication in
JHE
The Pure Spinor Formulation of Superstrings
In this lectures we outline the construction of pure spinor superstrings. We
consider both the open and closed pure spinor superstrings in critical and
noncritical dimensions and on flat and curved target spaces with RR flux. We
exhibit the integrability properties of pure spinor superstrings on curved
backgrounds with RR fluxes.Comment: These lectures have been given in the RTN Winter School on Strings,
Supergravity and Gauge Theories, CERN (2008). 32 pages, a typo correcte
Ramond-Ramond Central Charges in the Supersymmetry Algebra of the Superstring
The free action for the massless sector of the Type II superstring was
recently constructed using closed RNS superstring field theory. The
supersymmetry transformations of this action are shown to satisfy an N=2 D=10
SUSY algebra with Ramond-Ramond central charges.Comment: 10 pages harvmac te
Note About Classical Dynamics of Pure Spinor String on AdS_5 x S_5 Background
We will discuss some properties of the pure spinor string on the AdS_5 x S_5
background. Using the classical Hamiltonian analysis we will show that the
vertex operator for the massless state that is in the cohomology of the BRST
charges describes on-shell fluctuations around AdS_5 x S_5 background.Comment: 26. pages, added references, v2:corrected typo
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