9,526 research outputs found
A Non-Perturbative Superpotential With Symmetry
We compute the non-perturbative superpotential in -theory compactification
to four dimensions on a complex three-fold , where is a
rational elliptic surface. In contrast to examples considered previously, the
superpotential in this case has interesting modular properties; it is
essentially an theta function.Comment: Additional references and clarifications. Latex, 10 page
NeXSPheRIO results on elliptic flow at RHIC and connection with thermalization
Elliptic flow at RHIC is computed event-by-event with NeXSPheRIO. Reasonable
agreement with experimental results on is obtained. Various effects
are studied as well: reconstruction of impact parameter direction, freeze out
temperature, equation of state (with or without crossover), emission mecanism.Comment: Contribution to the Proceedings of the Quark-Gluon Plasma
Thermalization workshop. Content slightly increase
Super Quantum Mechanics in the Integral Form Formalism
We reformulate Super Quantum Mechanics in the context of integral forms. This
framework allows to interpolate between different actions for the same theory,
connected by different choices of Picture Changing Operators (PCO). In this way
we retrieve component and superspace actions, and prove their equivalence. The
PCO are closed integral forms, and can be interpreted as super Poincar\'e duals
of bosonic submanifolds embedded into a supermanifold.. We use them to
construct Lagrangians that are top integral forms, and therefore can be
integrated on the whole supermanifold. The and the
cases are studied, in a flat and in a curved supermanifold. In this formalism
we also consider coupling with gauge fields, Hilbert space of quantum states
and observables.Comment: 41 pages, no figures. Use birkjour.cls. Minor misprints, moved
appendix A and B in the main text. Version to be published in Annales H.
Poincar\'
The Geometry of Supermanifolds and New Supersymmetric Actions
We construct the Hodge dual for supermanifolds by means of the Grassmannian
Fourier transform of superforms. In the case of supermanifolds it is known that
the superforms are not sufficient to construct a consistent integration theory
and that the integral forms are needed. They are distribution-like forms which
can be integrated on supermanifolds as a top form can be integrated on a
conventional manifold. In our construction of the Hodge dual of superforms they
arise naturally. The compatibility between Hodge duality and supersymmetry is
exploited and applied to several examples. We define the irreducible
representations of supersymmetry in terms of integral and superforms in a new
way which can be easily generalised to several models in different dimensions.
The construction of supersymmetric actions based on the Hodge duality is
presented and new supersymmetric actions with higher derivative terms are
found. These terms are required by the invertibility of the Hodge operator.Comment: LateX2e, 51 pages. Corrected some further misprint
The formation of the primitive star SDSS J102915+172927: effect of the dust mass and the grain-size distribution
Understanding the formation of the extremely metal poor star
SDSS-J102915+172927 is of fundamental importance to improve our knowledge on
the transition between the first and second generation of stars in the
Universe. In this paper, we perform three-dimensional cosmological
hydrodynamical simulations of dust-enriched halos during the early stages of
the collapse process including a detailed treatment of the dust physics. We
employ the astrochemistry package \krome coupled with the hydrodynamical code
\textsc{enzo} assuming grain size distributions produced by the explosion of
core-collapse supernovae of 20 and 35 M primordial stars which are
suitable to reproduce the chemical pattern of the SDSS-J102915+172927 star. We
find that the dust mass yield produced from Population III supernovae
explosions is the most important factor which drives the thermal evolution and
the dynamical properties of the halos. Hence, for the specific distributions
relevant in this context, the composition, the dust optical properties, and the
size-range have only minor effects on the results due to similar cooling
functions. We also show that the critical dust mass to enable fragmentation
provided by semi-analytical models should be revised, as we obtain values one
order of magnitude larger. This determines the transition from disk
fragmentation to a more filamentary fragmentation mode, and suggests that
likely more than one single supernova event or efficient dust growth should be
invoked to get such a high dust content.Comment: Accepted on Ap
Primordial star formation: relative impact of H2 three-body rates and initial conditions
Population III stars are the first stars in the Universe to form at z=20-30
out of a pure hydrogen and helium gas in minihalos of 10^5-10^6 M .
Cooling and fragmentation is thus regulated via molecular hydrogen. At
densities above 10^8 cm, the three-body H2 formation rates are
particularly important for making the gas fully molecular. These rates were
considered to be uncertain by at least a few orders of magnitude. We explore
the impact of new accurate three-body H2 formation rates derived by Forrey
(2013) for three different minihalos, and compare to the results obtained with
three-body rates employed in previous studies. The calculations are performed
with the cosmological hydrodynamics code ENZO (release 2.2) coupled with the
chemistry package KROME (including a network for primordial chemistry), which
was previously shown to be accurate in high resolution simulations. While the
new rates can shift the point where the gas becomes fully molecular, leading to
a different thermal evolution, there is no trivial trend in how this occurs.
While one might naively expect the results to be inbetween the calculations
based on Palla et al. (1983) and Abel et al. (2002), the behavior can be close
to the former or the latter depending on the dark matter halo that is explored.
We conclude that employing the correct three-body rates is about as equally
important as the use of appropriate initial conditions, and that the resulting
thermal evolution needs to be calculated for every halo individually.Comment: 10 pages, 9 figures, A&A, 561, A13 (2014
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