2,145 research outputs found
Possibly New Charmed Baryon States from Decay
We examine the invariant mass spectrum of in decay measured by BABAR and find that through the 2-step processes of
, where denotes a
charmed baryon state, some of the peaks can be identified with the established
, and . Moreover, in
order to account for the measured spectrum, it is necessary to introduce a new
charmed baryon resonance with MeV.Comment: 8 pages, 1 figure, title changed and discussions updated, version
accepted for publication in Phys. Rev.
Damped Population Oscillation in a Spontaneously Decaying Two-Level Atom Coupled to a Monochromatic Field
We investigate the time evolution of atomic population in a two-level atom
driven by a monochromatic radiation field, taking spontaneous emission into
account. The Rabi oscillation exhibits amplitude damping in time caused by
spontaneous emission. We show that the semiclassical master equation leads in
general to an overestimation of the damping rate and that a correct
quantitative description of the damped Rabi oscillation can thus be obtained
only with a full quantum mechanical theory.Comment: 5 pages, 5 figure
Theoretical prediction of topological insulator in ternary rare earth chalcogenides
A new class of three-dimensional topological insulator, ternary rare earth
chalcogenides, is theoretically investigated with ab initio calculations. Based
on both bulk band structure analysis and the direct calculation of topological
surface states, we demonstrate that LaBiTe3 is a topological insulator. La can
be substituted by other rare earth elements, which provide candidates for novel
topological states such as quantum anomalous Hall insulator, axionic insulator
and topological Kondo insulator. Moreover, YBiTe3 and YSbTe3 are found to be
normal insulators. They can be used as protecting barrier materials for both
LaBiTe3 and Bi2Te3 families of topological insulators for their well matched
lattice constants and chemical composition.Comment: 5 pages, 3 figures and 1 tabl
A new puzzle for random interaction
We continue a series of numerical experiments on many-body systems with
random two-body interactions, by examining correlations in ratios in excitation
energies of yrast = 0, 2, 4, 6, 8 states. Previous studies, limited only to
= 0,2,4 states, had shown strong correlations in boson systems but not
fermion systems. By including states and considering different
scatter plots, strong and realistic correlations appear in both boson and
fermion systems. Such correlations are a challenge to explanations of random
interactions.Comment: 4 pages, 4 figure
Fivebranes from gauge theory
We study theories with sixteen supercharges and a discrete energy spectrum.
One class of theories has symmetry group . They arise as truncations
of super Yang Mills. They include the plane wave matrix model, 2+1
super Yang Mills on and super Yang Mills on . We explain how to obtain their gravity duals in a unified way.
We explore the regions of the geometry that are relevant for the study of some
1/2 BPS and near BPS states. This leads to a class of two dimensional (4,4)
supersymmetric sigma models with non-zero flux, including a massive
deformed WZW model. We show how to match some features of the string spectrum
with the Yang Mills theory.
The other class of theories are also connected to super Yang
Mills and arise by making some of the transverse scalars compact. Their vacua
are characterized by a 2d Yang Mills theory or 3d Chern Simons theory. These
theories realize peculiar superpoincare symmetry algebras in 2+1 or 1+1
dimensions with "non-central" charges. We finally discuss gravity duals of
super Yang Mills on .Comment: 50+24 pages, 9 figures, latex. v2: typos corrected, references adde
An SIDM Solution to the Extreme Diversity of Low-mass Halo Properties
The properties of low-mass dark matter halos appear to be remarkably diverse
relative to predictions of cold, collisionless dark matter, even in the
presence of baryons. We show that self-interacting dark matter can
simultaneously explain two extreme measurements of halo diversity in different
directions -- namely, the rotation curves of low-concentration halos associated
with gas-rich ultra-diffuse galaxies in the field and the inner density profile
of the dense substructure perturbing the strong lens galaxy SDSSJ0946+1006. We
present the first cosmological zoom-in simulation featuring strong dark matter
self-interactions in a galaxy group environment centered on a
host halo. These interactions produce
kiloparsec-scale cores in low-concentration isolated halos, which could host
the ultra-diffuse galaxies, while most surviving subhalos of the group-mass
host are deeply core-collapsed, yielding excellent candidates for the observed
dense strong-lens perturber. Our scenario can be further tested with
observations of galactic systems over a wide mass range.Comment: 10 pages, 6 figure
Strong Dark Matter Self-interactions Diversify Halo Populations Within and Surrounding the Milky Way
We perform a high-resolution cosmological zoom-in simulation of a Milky Way
(MW)-like system, which includes a realistic Large Magellanic Cloud analog,
using a large differential elastic dark matter self-interaction cross section
that reaches at relative
velocities of , motivated by observational
features of dwarf galaxies within and surrounding the MW. We explore the
effects of dark matter self-interactions on satellite, splashback, and isolated
halos through their abundance, central densities, maximum circular velocities,
orbital parameters, and correlations between these variables. We use an
effective constant cross section model to analytically predict the stages of
our simulated halos' gravothermal evolution, demonstrating that deviations from
the collisionless -- relation can be used to select
deeply core-collapsed halos, where is a halo's maximum circular
velocity and is the radius at which it occurs. We predict that a
sizable fraction () of subhalos with masses down to are deeply core-collapsed in our SIDM model. Core-collapsed
systems form of the total isolated halo population down to the
same mass; these isolated, core-collapsed halos would host faint dwarf galaxies
in the field with extremely steep central density profiles reminiscent of the
Tucana dwarf galaxy. Finally, most halos with masses above are core-forming in our simulation. Our study thus demonstrates
how self-interactions diversify halo populations in an
environmentally-dependent fashion within and surrounding MW-mass hosts,
providing a compelling avenue to address the diverse dark matter distributions
of observed dwarf galaxies.Comment: 28 pages, 17 figure
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