169 research outputs found
One-loop Regularization of Supergravity II: The Dilaton and the Superfield Formulation
The on-shell regularization of the one-loop divergences of supergravity
theories is generalized to include a dilaton of the type occurring in effective
field theories derived from superstring theory, and the superfield structure of
the one-loop corrections is given. Field theory anomalies and quantum
contributions to soft supersymmetry breaking are discussed. The latter are
sensitive to the precise choice of couplings that generate Pauli-Villars
masses, which in turn reflect the details of the underlying theory above the
scale of the effective cut-off. With a view to the implementation the
Green-Schwarz and other mechanisms for canceling field theory anomalies under a
U(1) gauge transformation and under the T-duality group of modular
transformations, we show that the K\"ahler potential renormalization for the
untwisted sector of orbifold compactification can be made invariant under these
groups.Comment: 46 pages, full postscript also available from
http://phyweb.lbl.gov/theorygroup/papers/43259.p
One-Loop Pauli-Villars Regularization of Supergravity I: Canonical Gauge Kinetic Energy
It is shown that the one-loop coefficients of on-shell operators of standard
supergravity with canonical gauge kinetic energy can be regulated by the
introduction of Pauli-Villars chiral and abelian gauge multiplets, subject to a
condition on the matter representations of the gauge group. Aspects of the
anomaly structure of these theories under global nonlinear symmetries and an
anomalous gauge symmetry are discussed.Comment: 46 pages, full postscript also available from
http://phyweb.lbl.gov/theorygroup/papers/preprints.html/41981.ps . Misprints
and errors in equations present in the original version have been correcte
Suplementação de vitamina C associada à densidade de criação no desempenho de frangos de corte
Avaliou-se o efeito da suplementação da vitamina C (75 e 150 mg/kg) na alimentação de frangos de corte machos sob condições de estresse de calor e superlotação. As aves foram criadas sobre "cama" de cavaco de madeira nas lotações de 10 e 14 aves/m². O delineamento experimental foi o inteiramente casualizado em esquema fatorial (3 níveis de vitamina C na ração e 2 lotações), com 5 repetições. Os resultados indicaram que o aumento da lotação de criação prejudicou (PThe effect of vitamin C supplementation (75 and 150 mg/kg) was evaluated in male broiler feeding under heat stress, crowding and normal floor space conditions. The results showed that crowding conditions (10 vs. 14 birds/m²) affected negatively (
Independent Component Separation from incomplete spherical data using wavelets. Application to CMB data analysis
Spectral matching ICA (SMICA) is a source separation method based on covariance matching in Fourier space that was designed to address in a flexible way some of the general problems raised by Cosmic Microwave Background data analysis. However, a common issue in astronomical data analysis is that the observations are unevenly sampled or incomplete maps with missing patches or intentionally masked parts. In addition, many astrophysical emissions are not well modeled as stationary processes over the sky. These effects impair data processing techniques in the spherical harmonics representation. This paper describes a new wavelet transform for spherical maps and proposes an extension of SMICA in this space-scale representation
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
Theory-Motivated Benchmark Models and Superpartners at the Tevatron
Recently published benchmark models have contained rather heavy
superpartners. To test the robustness of this result, several benchmark models
have been constructed based on theoretically well-motivated approaches,
particularly string-based ones. These include variations on anomaly and
gauge-mediated models, as well as gravity mediation. The resulting spectra
often have light gauginos that are produced in significant quantities at the
Tevatron collider, or will be at a 500 GeV linear collider. The signatures also
provide interesting challenges for the LHC. In addition, these models usually
account for electroweak symmetry breaking with relatively less fine-tuning than
previous benchmark models.Comment: 44 pages, 4 figures; some typos corrected. Revisions reflect
published versio
Supersymmetry and Superstring Phenomenology
We briefly cover the early history of supersymmetry, describe the relation of
SUSY quantum field theories to superstring theories and explain why they are
considered a likely tool to describe the phenomenology of high energy particle
theory beyond the Standard Model.Comment: 18 pages. To be published in ``Supersymmetry on the Eve of the LHC'',
a special volume of the European Physical Journal C (EPJC) dedicated to the
memory of Julius Wes
New D=4 gauged supergravities from N=4 orientifolds with fluxes
We consider classes of T_6 orientifolds, where the orientifold projection
contains an inversion I_{9-p} on 9-p coordinates, transverse to a Dp-brane. In
absence of fluxes, the massless sector of these models corresponds to diverse
forms of N=4 supergravity, with six bulk vector multiplets coupled to N=4
Yang--Mills theory on the branes. They all differ in the choice of the duality
symmetry corresponding to different embeddings of SU(1,1)\times SO(6,6+n) in
Sp(24+2n,R), the latter being the full group of duality rotations. Hence, these
Lagrangians are not related by local field redefinitions. When fluxes are
turned on one can construct new gaugings of N=4 supergravity, where the twelve
bulk vectors gauge some nilpotent algebra which, in turn, depends on the choice
of fluxes.Comment: 51 pages, 1 figure. Latex. Reference added. Typos corrected.
Discussion on gaugings expande
Parikh-Wilczek Tunneling from Noncommutative Higher Dimensional Black Holes
We study tunneling of massless and massive particles through the smeared
quantum horizon of the extra-dimensional Schwarzschild black holes. The
emission rate of the particles' tunneling is modified by noncommutativity
effects in a bulk spacetime of dimension . The issues of information loss
and possible correlations between emitted particles are discussed. We show that
even by considering both noncommutativity and braneworld effects, there is no
correlation between different modes of evaporation at least at late-time and
within approximations used in the calculations. However, incorporation of
quantum gravity effects such as modification of the standard dispersion
relation or generalization of the Heisenberg uncertainty principle, leads to
the correlation between emitted particles. Although time-evolution of these
correlations is not trivial, a part of information coming out of the black hole
can be preserved in these correlations. On the other hand, as a well-known
result of spacetime noncommutativity, a part of information may be preserved in
a stable black hole remnant.Comment: 23 pages, 1 figure, Accepted for publication in JHE
Reducing bumblefoot lesions in a group of captive Magellanic penguins (Spheniscus magellanicus) with the use of environmental enrichment
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