42 research outputs found
Normal ordering and boundary conditions for fermionic string coordinates
We build up normal ordered products for fermionic open string coordinates
consistent with boundary conditions. The results are obtained considering the
presence of antisymmetric tensor fields. We find a discontinuity of the normal
ordered products at string endpoints even in the absence of the background. We
discuss how the energy momentum tensor also changes at the world-sheet boundary
in such a way that the central charge keeps the standard value at string end
points.Comment: In this revised version we clarify the issue of consistency between
supersymmetry and boundary conditions and stress the fact that we are
considering flat space. we also add two more reference
Fermionic anticommutators for open superstrings in the presence of antisymmetric tensor field
We build up the anticommutator algebra for the fermionic coordinates of open
superstrings attached to branes with antisymmetric tensor fields. We use both
Dirac quantization and the symplectic Faddeev Jackiw approach. In the
symplectic case we find a way of generating the boundary conditions as zero
modes of the symplectic matrix by taking a discretized form of the action and
adding terms that vanish in the continuous limit. This way boundary conditions
can be handled as constraints.Comment: Revision: passage from discrete to continuous clarified, comment on
previous results using Dirac quantization included, typos corrected. Version
to appear in Phys. Lett.
Canonical Transformations and Gauge Fixing in the Triplectic Quantization
We show that the generators of canonical transformations in the triplectic
manifold must satisfy constraints that have no parallel in the usual field
antifield quantization. A general form for these transformations is presented.
Then we consider gauge fixing by means of canonical transformations in this
Sp(2) covariant scheme, finding a relation between generators and gauge fixing
functions. The existence of a wide class of solutions to this relation nicely
reflects the large freedom of the gauge fixing process in the triplectic
quantization. Some solutions for the generators are discussed. Our results are
then illustrated by the example of Yang Mills theory.Comment: A new section about the cohomological approach to the extended BRST
quantization has been included. Some new references were added too. Final
version to appear in Nucl. Phys.B. 12 pages, LATE
A superspace formulation of the BV action
We show that the BV (Batalin Vilkovisky) action, formulated with an extended
BRST symmetry (including the shift symmetry), is also invariant under an
extended anti-BRST transformation (where the antifields are the parameters of
the transformation), when the gauge fixing Lagrangian is both BRST and
anti-BRST invariant. We show that for a general gauge fixing Lagrangian, the BV
action can be written in a manifestly extended BRST invariant manner in a
superspace with one Grassmann coordinate whereas it can be expressed in a
manifestly extended BRST and anti-BRST invariant manner in a superspace with
two Grassmann coordinates when the gauge fixing Lagrangian is invariant under
both BRST and anti-BRST transformations.Comment: 20 page
Bulk versus boundary quantum states
An explicit holographic correspondence between bulk and boundary
quantum states is found in the form of a one to one mapping between scalar
field creation/annihilation operators. The mapping requires the introduction of
arbitrary energy scales and exhibits an ultraviolet-infrared duality: a small
regulating mass in the boundary theory corresponds to a large momentum cutoff
in the bulk. In the massless (conformal) limit of the boundary theory the
mapping covers the whole field spectrum of both theories. The mapping strongly
depends on the discretization of the field spectrum of compactified space
in Poincare coordinates.Comment: Minor changes in the text. Typos correction. References added.
Version to appear in Phys. Lett.
QCD/String holographic mapping and high energy scattering amplitudes
We find a one to one mapping between low energy string dilaton states in AdS
bulk and high energy glueball states on the corresponding boundary. This
holographic mapping leads to a relation between bulk and boundary scattering
amplitudes. From this relation and the dilaton action we find the appropriate
momentum scaling for high energy QCD amplitudes at fixed angles.Comment: Minor changes in text. Version accepted for publication in PL
Holographic model for dilepton production in p-p collisions
We propose a holographic model for dilepton production in proton-proton
collisions based on the exchange of vector mesons. The holographic hard wall
model is used to describe the dynamics and interactions of vector mesons and
baryons. We estimate the parameters lambda, mu, nu that characterize the
angular distribution of the produced dileptons in a region of q_T^2 << Q^2,
where perturbative QCD presents an effective strong coupling due to large
logarithm corrections.Comment: Revision: V4 In this version we modified the dimension of the
fermionic operator to match the canonical dimension of a baryonic operator.
This modification affected slightly our results with respect to v3. 25 pages,
3 Latex figures + 6 eps figures, 5 tables. To appear in Nucl. Phys.
AdS space compactification and holographic mapping in the AdS/CFT correspondence
Physical consistency of quantum fields in anti-de Sitter space time requires
that the space must be compactified by the inclusion of a boundary where
appropriate conditions are imposed. An interpretation for the presence of this
boundary is found taking AdS as a limiting case of the space generated by a
large number of coincident branes. The compactification of AdS leads to a
discretization of the spectrum of bulk fields. As a consequence, we find a one
to one mapping between the quantum states of scalar fields in AdS bulk and
boundary. Using this mapping as an approximation for the dual relation between
string dilaton field and scalar QCD glueballs the high energy QCD scaling is
reproduced. We also use this map to estimate the ratio of scalar glueball
masses.Comment: 5 pages, talk presented at "Renormalization Group and Anomalies in
Gravity and Cosmology", Ouro Preto, Brazil, March 200
Deep Inelastic Scattering in Holographic AdS/QCD Models
We review the description of deep inelastic scattering using some AdS/QCD
phenomenological models.Comment: Talk presented by NRFB at Light Cone 2009: Relativistic Hadronic and
Particle Physics, 8-13 Jul 2009, Sao Jose dos Campos, Brazi
Black-hole quasinormal modes and scalar glueballs in a finite-temperature AdS/QCD model
We use the holographic AdS/QCD soft-wall model to investigate the spectrum of
scalar glueballs in a finite temperature plasma. In this model, glueballs are
described by a massless scalar field in an AdS_5 black hole with a dilaton
soft-wall background. Using AdS/CFT prescriptions, we compute the boundary
retarded Green's function. The corresponding thermal spectral function shows
quasiparticle peaks at low temperatures. We also compute the quasinormal modes
of the scalar field in the soft-wall black hole geometry. The temperature and
momentum dependences of these modes are analyzed. The positions and widths of
the peaks of the spectral function are related to the frequencies of the
quasinormal modes. Our numerical results are found employing the power series
method and the computation of Breit-Wigner resonances.Comment: Revision: Results unchanged. More discussions on the model and on the
results. References added. 28 pages, 7 figures, 5 table