569 research outputs found
One-loop Correction and the Dilaton Runaway Problem
We examine the one-loop vacuum structure of an effective theory of gaugino
condensation coupled to the dilaton for string models in which the gauge
coupling constant does not receive string threshold corrections. The new
ingredients in our treatment are that we take into account the one-loop
correction to the dilaton K\"ahler potential and we use a formulation which
includes a chiral field corresponding to the gaugino bilinear. We find
through explicit calculation that supersymmetry in the Yang-Mills sector is
broken by gaugino condensation.
The dilaton and field have masses on the order of the gaugino
condensation scale independently of the dilaton VEV. Although the calculation
performed here is at best a model of the full gaugino condensation dynamics,
the result shows that the one-loop correction to the dilaton K\"ahler potential
as well as the detailed dynamics at the gaugino condensation scale may play an
important role in solving the dilaton runaway problem.Comment: 19 page
Reply to the comment on direct experimental evidence for a negative heat capacity in the liquid to gas phase transition in hydrogen cluster ions backbending of the caloric curve
IP
T3SS-dependent differential modulations of the jasmonic acid pathway in susceptible and resistant genotypes of Malus spp. challenged with Erwinia amylovora
Fire blight is a bacterial disease of Maloideae caused by Erwinia amylovora (Ea). This necrogenic enterobacterium uses a type III secretion system (T3SS) to inject type III effectors into the plant cells to cause disease on its susceptible hosts, including economically important crops like apple and pear. The expressions of marker genes of the salicylic acid (SA) and jasmonic acid (JA) defense regulation pathways were monitored by RT-qPCR in leaves of two apple genotypes, one susceptible and one resistant, challenged with a wild type strain, a T3SS-deficient strain or water. The transcriptional data taken together with hormone level measurements indicated that the SA pathway was similarly induced in both apple genotypes during infection by Ea. On the contrary, the data clearly showed a strong T3SS-dependent down-regulation of the JA pathway in leaves of the susceptible genotype but not in those of the resistant one. Accordingly, methyl-jasmonate treated susceptible plants displayed an increased resistance to Ea. Bacterial mutant analysis indicated that JA manipulation by Ea mainly relies on the type III effector DspA/E. Taken together, our data suggest that the T3SS-dependent down-regulation of the JA pathway is a critical step in the infection process of Malus spp. by Ea
Collision induced cluster fragmentation: From fragment size distributions to the caloric curve
IPMInternational audienceWe report on a cluster fragmentation study involving collisions of high-energy (60 keV/amu) H3+(H2)m hydrogen cluster ions (m=9, 11) with atomic helium or fullerenes. The experimental characterisation of the cluster fragmentation not only by the average fragment size distribution but also by a statistical analysis of the fragmentation events has become possible owing to a recently developed multi-coincidence technique in which all the fragments of all collisions occurring in the experiment are mass analysed on an event-by-event basis. By selecting specific decay reactions we can start after the energizing collision with a microcanonical cluster ion ensemble of fixed excitation energy. From the respective fragment distributions for these selected decay reactions we derive corresponding temperatures of the decaying cluster ions. The relation between this temperature and the excitation energy (caloric curve) exhibits the typical prerequisites of a first order phase transition in a finite system, in the present case signalling the transition from a bound cluster type situation to the free gas phase
Gravity duals of 2d supersymmetric gauge theories
We find new supergravity solutions generated by D5-branes wrapping a
four-cycle and preserving four and two supersymmetries. We first consider the
configuration in which the fivebranes wrap a four-cycle in a Calabi-Yau
threefold, which preserves four supersymmetries and is a gravity dual to the
Coulomb branch of two-dimensional gauge theories with N=(2,2) supersymmetry. We
also study the case of fivebranes wrapping a co-associative four-cycle in a
manifold of G_2-holonomy, which provides a gravity dual of N=(1,1)
supersymmetric Yang-Mills theory in two dimensions. We also discuss the
addition of unquenched fundamental matter fields to these backgrounds and find
the corresponding gravity solutions with flavor brane sources.Comment: 34 pages + appendices; v2: minor improvement
On the geometry of string duals with backreacting flavors
Making use of generalized calibrated geometry and G-structures we put the
problem of finding string-duals with smeared backreacting flavor branes in a
more mathematical setting. This more formal treatment of the problem allows us
to easily smear branes without good coordinate representations, establish
constraints on the smearing form and identify a topological central charge in
the SUSY algebra. After exhibiting our methods for a series of well known
examples, we apply them to the problem of flavoring a supergravity-dual to a
d=2+1 dimensional N=2 super Yang-Mills-like theory. We find new solutions to
both the flavored and unflavored systems. Interpretating these turns out to be
difficult.Comment: 38 pages - Typos corrected and references added - As published in
JHE
The ROAD MOVIE project - Resistance Of Apple against Diseases : Mechanisms Of Virulence and Identification of Effectors
- …