925 research outputs found
Dark Matter, Muon g-2 and Other SUSY Constraints
Recent developments constraining the SUSY parameter space are reviewed within
the framework of SUGRA GUT models. The WMAP data is seen to reduce the error in
the density of cold dark matter by about a factor of four, implying that the
lightest stau is only 5 -10 GeV heavier than the lightest neutralino when m_0,
m_{1/2} < 1 TeV. The CMD-2 re-analysis of their data has reduced the
disagreement between the Standard Model prediction and the Brookhaven
measurement of the muon magnetic moment to 1.9 sigma, while using the tau decay
data plus CVC, the disagreement is 0.7 sigma. (However, the two sets of data
remain inconsistent at the 2.9 sigma level.) The recent Belle and BABAR
measurements of the B -> phi K CP violating parameters and branching ratios are
discussed. They are analyzed theoretically within the BBNS improved
factorization method. The CP parameters are in disagreement with the Standard
Model at the 2.7 sigma level, and the branching ratios are low by a factor of
two or more over most of the parameter space. It is shown that both anomalies
can naturally be accounted for by adding a non-universal cubic soft breaking
term at M_G mixing the second and third generations.Comment: 16 pages, 7 figures, plenary talk at Beyond The Desert '03, Castle
Ringberg, Germany, June 9, 2003. Typos correcte
Non-supersymmetric Extremal RN-AdS Black Holes in N=2 Gauged Supergravity
We investigate extremal Reissner-Nordstrom-AdS black holes in
four-dimensional N=2 abelian gauged supergravity. We find a new attractor
equation which is not reduced to the one in the asymptotically flat spacetime.
Focusing on so-called the T^3-model with a single neutral vector multiplet, we
obtain non-supersymmetric extremal Reissner-Nordstrom-AdS black hole solutions
with regular event horizon in the D0-D4 and the D2-D6 charge configurations.
The negative cosmological constant emerges even without the Fayet-Iliopoulos
parameters. Furthermore, we also argue the formal description of the
non-supersymmetric black hole solutions of the T^3-model and the STU-model in
generic configurations.Comment: 23 pages, accepted version in JHE
The Tensor Hierarchies of Pure N=2,d=4,5,6 Supergravities
We study the supersymmetric tensor hierarchy of pure (gauged) N=2,d=4,5,6
supergravity and compare them with those of the pure, ungauged, theories
(worked out by Gomis and Roest for d=5) and the predictions of the Kac-Moody
approach made by Kleinschmidt and Roest. We find complete agreement in the
ungauged case but we also find that, after gauging, new Stueckelberg symmetries
reduce the number of independent "physical" top-forms. The analysis has to be
performed to all orders in fermion fields.
We discuss the construction of the worldvolume effective actions for the
p-branes which are charged with respect to the (p+1)-form potentials and the
relations between the tensor hierarchies and p-branes upon dimensional
reduction.Comment: LaTeX2e file, 20 pages, 1 figure Results refined by extension of the
analysis to all orders in fermion
Absence of a Fermi surface in classical minimal four-dimensional gauged supergravity
We demonstrate that the two point function of the supercurrent dual to the
gravitino in the four-dimensional extremal anti-de Sitter Reissner-Nordstrom
black hole does not exhibit a Fermi surface singularity. In our analysis, we
utilize the ingoing Eddington-Finkelstein coordinate system, which enables us
to bypass certain complications in the determination of the allowed near
horizon behavior of the gravitino field at zero frequency. We check that our
method agrees with previous results for the massless charged Dirac field.Comment: 12 pages, 1 figur
Supersymmetric Charged Clouds in AdS_5
We consider supersymmetric holographic flows that involve background gauge
fields dual to chemical potentials in the boundary field theory. We use a
consistent truncation of gauged N=8 supergravity in five dimensions and we give
a complete analysis of the supersymmetry conditions for a large family of
flows. We examine how the well-known supersymmetric flow between two fixed
points is modified by the presence of the chemical potentials and this yields a
new, completely smooth, solution that interpolates between two global AdS
spaces of different radii and with different values of the chemical potential.
We also examine some black-hole-like singular flows and a new
non-supersymmetric black hole solution. We comment on the interpretation of our
new solutions in terms of giant gravitons and discuss the implications of our
work for finding black-hole solutions in AdS geometries.Comment: 31 pages, 6 figures; minor corrections, updated reference
Protein disulfide-isomerase interacts with a substrate protein at all stages along its folding pathway
In contrast to molecular chaperones that couple protein folding to ATP hydrolysis, protein disulfide-isomerase (PDI) catalyzes protein folding coupled to formation of disulfide bonds (oxidative folding). However, we do not know how PDI distinguishes folded, partly-folded and unfolded protein substrates. As a model intermediate in an oxidative folding pathway, we prepared a two-disulfide mutant of basic pancreatic trypsin inhibitor (BPTI) and showed by NMR that it is partly-folded and highly dynamic. NMR studies show that it binds to PDI at the same site that binds peptide ligands, with rapid binding and dissociation kinetics; surface plasmon resonance shows its interaction with PDI has a Kd of ca. 10â5 M. For comparison, we characterized the interactions of PDI with native BPTI and fully-unfolded BPTI. Interestingly, PDI does bind native BPTI, but binding is quantitatively weaker than with partly-folded and unfolded BPTI. Hence PDI recognizes and binds substrates via permanently or transiently unfolded regions. This is the first study of PDI's interaction with a partly-folded protein, and the first to analyze this folding catalyst's changing interactions with substrates along an oxidative folding pathway. We have identified key features that make PDI an effective catalyst of oxidative protein folding â differential affinity, rapid ligand exchange and conformational flexibility
Exactly Marginal Deformations and Global Symmetries
We study the problem of finding exactly marginal deformations of N=1
superconformal field theories in four dimensions. We find that the only way a
marginal chiral operator can become not exactly marginal is for it to combine
with a conserved current multiplet. Additionally, we find that the space of
exactly marginal deformations, also called the "conformal manifold," is the
quotient of the space of marginal couplings by the complexified continuous
global symmetry group. This fact explains why exactly marginal deformations are
ubiquitous in N=1 theories. Our method turns the problem of enumerating exactly
marginal operators into a problem in group theory, and substantially extends
and simplifies the previous analysis by Leigh and Strassler. We also briefly
discuss how to apply our analysis to N=2 theories in three dimensions.Comment: 23 pages, 2 figure
A frequentist framework of inductive reasoning
Reacting against the limitation of statistics to decision procedures, R. A.
Fisher proposed for inductive reasoning the use of the fiducial distribution, a
parameter-space distribution of epistemological probability transferred
directly from limiting relative frequencies rather than computed according to
the Bayes update rule. The proposal is developed as follows using the
confidence measure of a scalar parameter of interest. (With the restriction to
one-dimensional parameter space, a confidence measure is essentially a fiducial
probability distribution free of complications involving ancillary statistics.)
A betting game establishes a sense in which confidence measures are the only
reliable inferential probability distributions. The equality between the
probabilities encoded in a confidence measure and the coverage rates of the
corresponding confidence intervals ensures that the measure's rule for
assigning confidence levels to hypotheses is uniquely minimax in the game.
Although a confidence measure can be computed without any prior distribution,
previous knowledge can be incorporated into confidence-based reasoning. To
adjust a p-value or confidence interval for prior information, the confidence
measure from the observed data can be combined with one or more independent
confidence measures representing previous agent opinion. (The former confidence
measure may correspond to a posterior distribution with frequentist matching of
coverage probabilities.) The representation of subjective knowledge in terms of
confidence measures rather than prior probability distributions preserves
approximate frequentist validity.Comment: major revisio
Holographic renormalization and supersymmetry
Holographic renormalization is a systematic procedure for regulating
divergences in observables in asymptotically locally AdS spacetimes. For dual
boundary field theories which are supersymmetric it is natural to ask whether
this defines a supersymmetric renormalization scheme. Recent results in
localization have brought this question into sharp focus: rigid supersymmetry
on a curved boundary requires specific geometric structures, and general
arguments imply that BPS observables, such as the partition function, are
invariant under certain deformations of these structures. One can then ask if
the dual holographic observables are similarly invariant. We study this
question in minimal N = 2 gauged supergravity in four and five dimensions. In
four dimensions we show that holographic renormalization precisely reproduces
the expected field theory results. In five dimensions we find that no choice of
standard holographic counterterms is compatible with supersymmetry, which leads
us to introduce novel finite boundary terms. For a class of solutions
satisfying certain topological assumptions we provide some independent tests of
these new boundary terms, in particular showing that they reproduce the
expected VEVs of conserved charges.Comment: 70 pages; corrected typo
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