6,109 research outputs found

### Sine-Gordon-like action for the Superstring in AdS(5) x S(5)

We propose an action for a sine-Gordon-like theory, which reproduces the
classical equations of motion of the Green-Schwarz-Metsaev-Tseytlin superstring
on AdS(5) x S(5). The action is relativistically invariant. It is a
mass-deformed gauged WZW model for SO(4,1) x SO(5) / SO(4) x SO(4) interacting
with fermions.Comment: 19 pages, LaTeX; v2: added discussion of zero modes in Section 3; v3:
improved presentatio

### Anomalous dimension and local charges

AdS space is the universal covering of a hyperboloid. We consider the action
of the deck transformations on a classical string worldsheet in $AdS_5\times
S^5$. We argue that these transformations are generated by an infinite linear
combination of the local conserved charges. We conjecture that a similar
relation holds for the corresponding operators on the field theory side. This
would be a generalization of the recent field theory results showing that the
one loop anomalous dimension is proportional to the Casimir operator in the
representation of the Yangian algebra.Comment: 10 pages, LaTeX; v2: added explanations, reference

### On complete integrability of the Mikhailov-Novikov-Wang system

We obtain compatible Hamiltonian and symplectic structure for a new
two-component fifth-order integrable system recently found by Mikhailov,
Novikov and Wang (arXiv:0712.1972), and show that this system possesses a
hereditary recursion operator and infinitely many commuting symmetries and
conservation laws, as well as infinitely many compatible Hamiltonian and
symplectic structures, and is therefore completely integrable. The system in
question admits a reduction to the Kaup--Kupershmidt equation.Comment: 5 pages, no figure

### Analysis of segregated boundary-domain integral equations for mixed variable-coefficient BVPs in exterior domains

This is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2011 Birkhäuser Boston.Some direct segregated systems of boundary–domain integral equations (LBDIEs) associated with the mixed boundary value problems for scalar PDEs with variable coefficients in exterior domains are formulated and analyzed in the paper. The LBDIE equivalence to the original boundary value problems and the invertibility of the corresponding boundary–domain integral operators are proved in weighted Sobolev spaces suitable for exterior domains. This extends the results obtained by the authors for interior domains in non-weighted Sobolev spaces.The work was supported by the grant EP/H020497/1 ”Mathematical analysis of localised boundary-domain integral equations for BVPs with variable coefficients” of the EPSRC, UK

### Phenomenology of B -> pi pi, pi K Decays at O(alpha^2 beta_0) in QCD Factorization

We study O(alpha^2 beta_0) perturbative corrections to matrix elements
entering two-body exclusive decays of the form B -> pi pi, pi K in the QCD
factorization formalism, including chirally enhanced power corrections, and
discuss the effect of these corrections on direct CP asymmetries, which receive
their first contribution at O(alpha). We find that the O(alpha^2 beta_0)
corrections are often as large as the O(alpha) corrections. We find large
uncertainties due to renormalization scale dependence as well as poor knowledge
of the non-perturbative parameters. We assess the effect of the perturbative
corrections on the direct CP violation parameters of B -> pi^+ pi^-.Comment: 27 pages, 5 figures. Updated input parameters and added citations;
expanded discussio

### Numerics of boundary-domain integral and integro-differential equations for BVP with variable coefficient in 3D

This is the post-print version of the article. The official published version can be accessed from the links below - Copyright @ 2013 Springer-VerlagA numerical implementation of the direct boundary-domain integral and integro-differential equations, BDIDEs, for treatment of the Dirichlet problem for a scalar elliptic PDE with variable coefﬁcient in a three-dimensional domain is discussed. The mesh-based discretisation of the BDIEs with tetrahedron domain elements in conjunction with collocation method leads to a system of linear algebraic equations (discretised BDIE). The involved fully populated matrices are approximated by means of the H-Matrix/adaptive cross approximation technique. Convergence of the method is investigated.This study is partially supported by the EPSRC grant EP/H020497/1:"Mathematical Analysis of Localised-Boundary-Domain Integral Equations for Variable-Coefficients
Boundary Value Problems"

### Plane wave limit of local conserved charges

We study the plane wave limit of the Backlund transformations for the
classical string in AdS space times a sphere and obtain an explicit expression
for the local conserved charges. We show that the Pohlmeyer charges become in
the plane wave limit the local integrals of motion of the free massive field.
This fixes the coefficients in the expansion of the anomalous dimension as the
sum of the Pohlmeyer charges.Comment: v2: added explanation

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