8,373 research outputs found
Oblique and curved D-branes in IIB plane-wave string theory
Oblique Dp-branes in the maximally supersymmetric type IIB plane-wave
background are constructed in terms of boundary states, as well as from the
open string point of view. These Dp-branes, whose existence was anticipated by
Hikida and Yamaguchi from general supersymmetry arguments, have an isometry
that is a subgroup of the diagonal SO(4) symmetry of the background. The
oblique D3-brane is found to preserve four dynamical and four kinematical
supersymmetries while the oblique D5-brane preserves one half of both the
dynamical and kinematical supersymmetries. We also discuss the open-string
boundary conditions for curved D7- and D5-branes, and analyze their
supersymmetry.Comment: 27 page
Self-dual Yang-Mills fields in pseudoeuclidean spaces
The self-duality Yang-Mills equations in pseudoeuclidean spaces of dimensions
are investigated. New classes of solutions of the equations are
found. Extended solutions to the D=10, N=1 supergravity and super Yang-Mills
equations are constructed from these solutions.Comment: 9 pages, LaTeX, no figure
Effective Gap Equation for the Inhomogeneous LOFF Superconductive Phase
We present an approximate gap equation for different crystalline structures
of the LOFF phase of high density QCD at T=0. This equation is derived by using
an effective condensate term obtained by averaging the inhomogeneous condensate
over distances of the order of the crystal lattice size. The approximation is
expected to work better far off any second order phase transition. As a
function of the difference of the chemical potentials of the up and down
quarks, , we get that the octahedron is energetically favored from
to , where is the gap for
the homogeneous phase, while in the range the face
centered cube prevails. At a first order phase
transition to the normal phase occurs.Comment: 11 pages, 5 figure
Attosecond pulse shaping around a Cooper minimum
High harmonic generation (HHG) is used to measure the spectral phase of the
recombination dipole matrix element (RDM) in argon over a broad frequency range
that includes the 3p Cooper minimum (CM). The measured RDM phase agrees well
with predictions based on the scattering phases and amplitudes of the
interfering s- and d-channel contributions to the complementary photoionization
process. The reconstructed attosecond bursts that underlie the HHG process show
that the derivative of the RDM spectral phase, the group delay, does not have a
straight-forward interpretation as an emission time, in contrast to the usual
attochirp group delay. Instead, the rapid RDM phase variation caused by the CM
reshapes the attosecond bursts.Comment: 5 pages, 5 figure
The Ginzburg-Landau Free Energy Functional of Color Superconductivity at Weak Coupling
We derive the Ginzburg-Landau free energy functional of color
superconductivity in terms of the thermal diagrams of QCD in its perturbative
region. The zero mode of the quadratic term coefficient yields the same
transition temperature, including the pre-exponential factor, as the one
obtained previously from the Fredholm determinant of the two quark scattering
amplitude. All coefficients of the free energy can be made identical to those
of a BCS model by setting the Fermi velocity of the latter equal to the speed
of light. We also calculate the induced symmetric color condensate near
and find that it scales as the cubic power of the dominant antisymmetric color
component. We show that in the presence of an inhomogeneity and a nonzero gauge
potential, while the color-flavor locked condensate dominates in the bulk, the
unlocked condensate, the octet, emerges as a result of a simultaneous
color-flavor rotation in the core region of a vortex filament or at the
junction of super and normal phases.Comment: 32 pages, Plain Tex, 3 figure
Diquark Condensates and Compact Star Cooling
The effect of color superconductivity on the cooling of quark stars and
neutron stars with large quark cores is investigated. Various known and new
quark-neutrino processes are studied. As a result, stars being in the color
flavor locked (CFL) color superconducting phase cool down extremely fast. Quark
stars with no crust cool down too rapidly in disagreement with X-ray data. The
cooling of stars being in the N_f =2 color superconducting (2SC) phase with a
crust is compatible with existing X-ray data. Also the cooling history of stars
with hypothetic pion condensate nuclei and a crust does not contradict the
data.Comment: 10 pages, 5 figures, accepted for publication in Ap
Effects of maternal subnutrition during early pregnancy on cow hematological profiles and offspring physiology and vitality in two beef breeds
This experiment evaluated the effects of subnutrition during early gestation on hematology in cows (Bos Taurus) and on hematological, metabolic, endocrine, and vitality parameters in their calves. Parda de Montaña and Pirenaica dams were inseminated and assigned to either a control (CONTROL, 100% requirements) or a nutrientârestricted group (SUBNUT, 65%) during the first third of gestation. Dam blood samples were collected on days 20 and 253 of gestation, and calf samples were obtained during the first days of life. Pirenaica dams presented higher red series parameters than Parda de Montaña dams, both in the first and the last months of gestation. During early pregnancy, granulocyte numbers and mean corpuscular hemoglobin were lower in PirenaicaâSUBNUT than in PirenaicaâCONTROL cows. Calves from the SUBNUT cows did not show a physiological reduction in red series values in early life, suggesting later maturation of the hematopoietic system. Poor maternal nutrition affected calf endocrine parameters. Newborns from dystocic parturitions showed lower NEFA concentrations and weaker vitality responses. In conclusion, maternal nutrition had shortâterm effects on cow hematology, Pirenaica cows showing a higher susceptibility to undernutrition; and a longâterm effect on their offspring endocrinology, SUBNUT newborns showing lower levels of IGFâ1 and higher levels of cortisol.This work was supported by the Spanish Ministry of Economy and Business and the European Union Regional Development Funds (INIA RTA 2013â00059âC02 and INIA RZP 2015â001) and the Government of Aragon under the Grant Research Group Funds (A14_17R). A. Noya received a PhD grant from INIAâGovernment of Aragon
Two-loop AdS_5 x S^5 superstring: testing asymptotic Bethe ansatz and finite size corrections
We continue the investigation of two-loop string corrections to the energy of
a folded string with a spin S in AdS_5 and an angular momentum J in S^5, in the
scaling limit of large J and S with ell=pi J/(lambda^(1/2) ln S)=fixed. We
compute the generalized scaling function at two-loop order f_2(ell) both for
small and large values of ell matching the predictions based on the asymptotic
Bethe ansatz. In particular, in the small ell expansion, we derive an exact
integral form for the ell-dependent coefficient of the Catalan's constant term
in f_2(ell). Also, by resumming a certain subclass of multi-loop Feynman
diagrams we obtain an exact expression for the leading (ln ell) part of
f(lambda^(1/2), ell) which is valid to any order in the alpha'~1/lambda^(1/2)
expansion. At large ell the string energy has a BMN-like expansion and the
first few leading coefficients are expected to be the same at weak and at
strong coupling. We provide a new example of this non-renormalization for the
term which is generated at two loops in string theory and at one-loop in gauge
theory (sub-sub-leading in 1/J). We also derive a simple algebraic formula for
the term of maximal transcendentality in f_2(ell) expanded at large ell. In the
second part of the paper we initiate the study of 2-loop finite size
corrections to the string energy by formally compactifying the spatial
world-sheet direction in the string action expanded near long fast-spinning
string. We observe that the leading finite-size corrections are of "Casimir"
type coming from terms containing at least one massless propagator. We consider
in detail the one-loop order (reproducing the leading Landau-Lifshitz model
prediction) and then focus on the two-loop contributions to the (1/ln S) term
(for J=0). We find that in a certain regularization scheme used to discard
power divergences the two-loop coefficient of the (1/ln S) term appears to
vanish.Comment: 50 pages, 4 figures v2: typos corrected, references adde
Methods for Volumetric Reconstruction of Visual Scenes
In this paper, we present methods for 3D volumetric reconstruction of visual scenes photographed by multiple calibrated cameras placed at arbitrary viewpoints. Our goal is to generate a 3D model that can be rendered to synthesize new photo-realistic views of the scene. We improve upon existing voxel coloring/space carving approaches by introducing new ways to compute visibility and photo-consistency, as well as model infinitely large scenes. In particular, we describe a visibility approach that uses all possible color information from the photographs during reconstruction, photo-consistency measures that are more robust and/or require less manual intervention, and a volumetric warping method for application of these reconstruction methods to large-scale scenes
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