448 research outputs found
BF models, Duality and Bosonization on higher genus surfaces
The generating functional of two dimensional field theories coupled to
fermionic fields and conserved currents is computed in the general case when
the base manifold is a genus g compact Riemann surface. The lagrangian density
is written in terms of a globally defined 1-form and a
multi-valued scalar field . Consistency conditions on the periods of
have to be imposed. It is shown that there exist a non-trivial dependence of
the generating functional on the topological restrictions imposed to . In
particular if the periods of the field are constrained to take values , with any integer, then the partition function is independent of the
chosen spin structure and may be written as a sum over all the spin structures
associated to the fermions even when one started with a fixed spin structure.
These results are then applied to the functional bosonization of fermionic
fields on higher genus surfaces. A bosonized form of the partition function
which takes care of the chosen spin structure is obtainedComment: 17 page
Baryonic Condensates on the Conifold
We provide new evidence for the gauge/string duality between the baryonic
branch of the cascading SU(k(M+1)) \times SU(kM) gauge theory and a family of
type IIB flux backgrounds based on warped products of the deformed conifold and
R^{3,1}. We show that a Euclidean D5-brane wrapping all six deformed conifold
directions can be used to measure the baryon expectation values, and present
arguments based on kappa-symmetry and the equations of motion that identify the
gauge bundles required to ensure worldvolume supersymmetry of this object.
Furthermore, we investigate its coupling to the pseudoscalar and scalar modes
associated with the phase and magnitude, respectively, of the baryon
expectation value. We find that these massless modes perturb the
Dirac-Born-Infeld and Chern-Simons terms of the D5-brane action in a way
consistent with our identification of the baryonic condensates. We match the
scaling dimension of the baryon operators computed from the D5-brane action
with that found in the cascading gauge theory. We also derive and numerically
evaluate an expression that describes the variation of the baryon expectation
values along the supergravity dual of the baryonic branch.Comment: 34 pages, 1 figure; v2 typos corrected, references added; v3 added
comment on \kappa-symmetry of Euclidean D5-brane, published in JHE
Adding flavour to the Polchinski-Strassler background
As an extension of holography with flavour, we analyze in detail the
embedding of a D7-brane probe into the Polchinski-Strassler gravity background,
in which the breaking of conformal symmetry is induced by a 3-form flux G_3.
This corresponds to giving masses to the adjoint chiral multiplets. We consider
the N=2 supersymmetric case in which one of the adjoint chiral multiplets is
kept massless while the masses of the other two are equal. This setup requires
a generalization of the known expressions for the backreaction of G_3 in the
case of three equal masses to generic mass values. We work to second order in
the masses to obtain the embedding of D7-brane probes in the background. At
this order, the 2-form potentials corresponding to the background flux induce
an 8-form potential which couples to the worldvolume of the D7-branes. We show
that the embeddings preserve an SU(2) x SU(2) symmetry. We study possible
embeddings both analytically in a particular approximation, as well as
numerically. The embeddings preserve supersymmetry, as we investigate using the
approach of holographic renormalization. The meson spectrum associated to one
of the embeddings found reflects the presence of the adjoint masses by
displaying a mass gap.Comment: LaTeX, 50 pages, 9 figure
D3/D7 Inflationary Model and M-theory
A proposal is made for a cosmological D3/D7 model with a constant magnetic
flux along the D7 world-volume. It describes an N=2 gauge model with
Fayet-Iliopoulos terms and the potential of the hybrid P-term inflation. The
motion of the D3-brane towards D7 in a phase with spontaneously broken
supersymmetry provides a period of slow-roll inflation in the de Sitter valley,
the role of the inflaton being played by the distance between D3 and D7-branes.
After tachyon condensation a supersymmetric ground state is formed: a D3/D7
bound state corresponding to an Abelian non-linear (non-commutative) instanton.
In this model the existence of a non-vanishing cosmological constant is
associated with the resolution of the instanton singularity. We discuss a
possible embedding of this model into a compactified M-theory setup.Comment: 30 pages, 4 figures, LaTeX; v2, minor typos corrected, one reference
adde
Time Evolution via S-branes
Using S(pacelike)-branes defined through rolling tachyon solutions, we show
how the dynamical formation of D(irichlet)-branes and strings in tachyon
condensation can be understood. Specifically we present solutions of S-brane
actions illustrating the classical confinement of electric and magnetic flux
into fundamental strings and D-branes. The role of S-branes in string theory is
further clarified and their RR charges are discussed. In addition, by examining
``boosted'' S-branes, we find what appears to be a surprising dual S-brane
description of strings and D-branes, which also indicates that the critical
electric field can be considered as a self-dual point in string theory. We also
introduce new tachyonic S-branes as Euclidean counterparts to non-BPS branes.Comment: 62 pages, 10 figures. v2 references adde
Supersymmetric Branes on AdS_5 x Y^{p,q} and their Field Theory Duals
We systematically study supersymmetric embeddings of D-brane probes of
different dimensionality in the AdS_5xY^{p,q} background of type IIB string
theory. The main technique employed is the kappa symmetry of the probe's
worldvolume theory. In the case of D3-branes, we recover the known three-cycles
dual to the dibaryonic operators of the gauge theory and we also find a new
family of supersymmetric embeddings. The BPS fluctuations of dibaryons are
analyzed and shown to match the gauge theory results. Supersymmetric
configurations of D5-branes, representing domain walls, and of spacetime
filling D7-branes (which can be used to add flavor) are also found. We also
study the baryon vertex and some other embeddings which break supersymmetry but
are nevertheless stable.Comment: LaTeX, 2 figures, 54 pages; v2: discussions sharpened at several
points, new subsection and references adde
Global Search for New Physics with 2.0/fb at CDF
Data collected in Run II of the Fermilab Tevatron are searched for
indications of new electroweak-scale physics. Rather than focusing on
particular new physics scenarios, CDF data are analyzed for discrepancies with
the standard model prediction. A model-independent approach (Vista) considers
gross features of the data, and is sensitive to new large cross-section
physics. Further sensitivity to new physics is provided by two additional
algorithms: a Bump Hunter searches invariant mass distributions for "bumps"
that could indicate resonant production of new particles; and the Sleuth
procedure scans for data excesses at large summed transverse momentum. This
combined global search for new physics in 2.0/fb of ppbar collisions at
sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D
Rapid Communication
Observation of Orbitally Excited B_s Mesons
We report the first observation of two narrow resonances consistent with
states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar
collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the
Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed
as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+,
\bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1})
= 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
- …