23,717 research outputs found
Note about a second "evidence" for a WIMP annual modulation
This note, with its five questions, is intended to contribute to a
clarification about a claimed "evidence" by the DAMA group of an annual
modulation of the counting rate of a Dark Matter NaI(Tl) detector as due to a
neutralino (SUSY-LSP) Dark Matter candidate.Comment: LaTex, 3 pages, 2 figure
Phenomenological Implications of Supersymmetric Family Non-universal U(1)-prime Models
We construct a class of anomaly-free supersymmetric U(1)' models that are
characterized by family non-universal U(1)' charges motivated from E_6
embeddings. The family non-universality arises from an interchange of the
standard roles of the two SU(5) 5* representations within the 27 of E_6 for the
third generation. We analyze U(1)' and electroweak symmetry breaking and
present the particle mass spectrum. The models, which include additional Higgs
multiplets and exotic quarks at the TeV scale, result in specific patterns of
flavor-changing neutral currents in the b to s transitions that can accommodate
the presently observed deviations inthis sector from the SM predictions.Comment: 25 pages, 3 figure
Diquark and light four-quark states
Four-quark states with different internal clusters are discussed within the
constituent quark model. It is pointed out that the diquark concept is not
meaningful in the construction of a tetraquark interpolating current in the QCD
sum rule approach, and hence existing sum-rule studies of four-quark states are
incomplete. An updated QCD sum-rule determination of the properties of diquark
clusters is then used as input for the constituent quark model to obtain the
masses of light tetraquark states ({\it i.e.\} a bound state of two
diquark clusters). The results support the identification of ,
and as the light tetraquark states, and seem to
be inconsistent with the tetraquark state interpretation of the new BES
observations of the near-threshold enhancements, X(1835) and X(1812),
with the possible exception that X(1576) may be an "exotic" first orbital
excitation of or .Comment: 7 pages, 4 eps figures, RevTex, two figures and some references
added, published version in PR
Segmental Spatiotemporal CNNs for Fine-grained Action Segmentation
Joint segmentation and classification of fine-grained actions is important
for applications of human-robot interaction, video surveillance, and human
skill evaluation. However, despite substantial recent progress in large-scale
action classification, the performance of state-of-the-art fine-grained action
recognition approaches remains low. We propose a model for action segmentation
which combines low-level spatiotemporal features with a high-level segmental
classifier. Our spatiotemporal CNN is comprised of a spatial component that
uses convolutional filters to capture information about objects and their
relationships, and a temporal component that uses large 1D convolutional
filters to capture information about how object relationships change across
time. These features are used in tandem with a semi-Markov model that models
transitions from one action to another. We introduce an efficient constrained
segmental inference algorithm for this model that is orders of magnitude faster
than the current approach. We highlight the effectiveness of our Segmental
Spatiotemporal CNN on cooking and surgical action datasets for which we observe
substantially improved performance relative to recent baseline methods.Comment: Updated from the ECCV 2016 version. We fixed an important
mathematical error and made the section on segmental inference cleare
Thermal conduction and particle transport in strong MHD turbulence, with application to galaxy-cluster plasmas
We investigate field-line separation in strong MHD turbulence analytically
and with direct numerical simulations. We find that in the
static-magnetic-field approximation the thermal conductivity in galaxy clusters
is reduced by a factor of about 5-10 relative to the Spitzer thermal
conductivity of a non-magnetized plasma. We also estimate how the thermal
conductivity would be affected by efficient turbulent resistivity.Comment: Major revision: higher resolution simulations lead to significantly
different conclusions. 26 pages, 10 figure
Langevin Dynamics of the vortex matter two-stage melting transition in Bi_2Sr_2CaCu_2O in the presence of straight and of tilted columnar defects
In this paper we use London Langevin molecular dynamics simulations to
investigate the vortex matter melting transition in the highly anisotropic
high-temperature superconductor material Bi_2Sr_2CaCu_2O in the
presence of low concentration of columnar defects (CDs). We reproduce with
further details our previous results obtained by using Multilevel Monte Carlo
simulations that showed that the melting of the nanocrystalline vortex matter
occurs in two stages: a first stage melting into nanoliquid vortex matter and a
second stage delocalization transition into a homogeneous liquid. Furthermore,
we report on new dynamical measurements in the presence of a current that
identifies clearly the irreversibility line and the second stage delocalization
transition. In addition to CDs aligned along the c-axis we also simulate the
case of tilted CDs which are aligned at an angle with respect to the applied
magnetic field. Results for CDs tilted by with respect to c-axis
show that the locations of the melting and delocalization transitions are not
affected by the tilt when the ratio of flux lines to CDs remains constant. On
the other hand we argue that some dynamical properties and in particular the
position of the irreversibility line should be affected.Comment: 13 pages, 11 figure
- …