3,608 research outputs found
Spin-Orbit and Tensor Forces in Heavy-quark Light-quark Mesons: Implications of the New Ds state at 2.32 GeV
We consider the spectroscopy of heavy-quark light-quark mesons with a simple
model based on the non-relativistic reduction of vector and scalar exchange
between fermions. Four forces are induced: the spin-orbit forces on the light
and heavy quark spins, the tensor force, and a spin-spin force. If the vector
force is Coulombic, the spin-spin force is a contact interaction, and the
tensor force and spin-orbit force on the heavy quark to order are
directly proportional. As a result, just two independent parameters
characterize these perturbations. The measurement of the masses of three p-wave
states suffices to predict the mass of the fourth. This technique is applied to
the system, where the newly discovered state at 2.32 GeV provides the
third measured level, and to the system. The mixing of the two
p-wave states is reflected in their widths and provides additional constraints.
The resulting picture is at odds with previous expectations and raises new
puzzles.Comment: 6 pages, 1 figur
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Acceptance and commitment therapy as an adjunct to the MOVE! programme: a randomized controlled trial.
ObjectiveThe current study tested the efficacy of an acceptance and commitment therapy (ACT) group intervention for disinhibited eating behaviour as an adjunct to the Veterans Affairs MOVE!© weight management programme.MethodsVeterans (N = 88) with overweight or obesity who completed the MOVE! weight management programme and self-identified as having problems with 'stress-related eating' were randomized to four 2-h weekly ACT sessions or a continued behavioural weight-loss (BWL) intervention. Assessments were completed at baseline, post-treatment and 3- and 6-month follow-up on outcomes of interest including measures of disinhibited eating patterns, obesity-related quality of life, weight-related experiential avoidance and weight.ResultsThe BWL group exhibited significantly greater reductions in binge eating behaviour at post-treatment compared with the ACT group. Significant improvements in other outcomes were found with minimal differences between groups. In both groups, decreases in weight-related experiential avoidance were related to improvements in binge eating behaviour.ConclusionsTaken together, the continued BWL intervention resulted in larger improvements in binge eating behaviour than the ACT intervention. The two groups showed similar improvements in other disinhibited eating outcomes. Future studies are encouraged to determine if more integrated or longer duration of ACT treatment may maximize eating outcomes in MOVE.Trial Registration Number: This trial was registered with ClinicalTrials.gov database (NCT01757847)
Low scale B-L extension of the Standard Model at the LHC
The fact that neutrinos are massive indicates that the Standard Model (SM)
requires extension. We propose a low energy (<TeV) B-L extension of the SM,
which is based on the gauge group SU(3)_C x SU(2)_L x U(1)_Y x U(1)_{B-L}. We
show that this model provides a natural explanation for the presence of three
right-handed neutrinos in addition to an extra gauge boson and a new scalar
Higgs. Therefore, it can lead to very interesting phenomenological implications
different from the SM results which can be tested at the LHC. Also we analyze
the muon anomalous magnetic moment in this class of models. We show that
one-loop with exchange Z' may give dominant new contribution ~ few x 10^{-11}.Comment: 12 page
Relativistic Symmetry Suppresses Quark Spin-Orbit Splitting
Experimental data indicate small spin-orbit splittings in hadrons. For
heavy-light mesons we identify a relativistic symmetry that suppresses these
splittings. We suggest an experimental test in electron-positron annihilation.
Furthermore, we argue that the dynamics necessary for this symmetry are
possible in QCD.Comment: 16 pages, LaTeX. Two postscript figures. Final version to be
published in Physical Review Letter
Study of decays
We investigate the production of the novel -wave mesons and
, identified as and , in heavy
meson decays, respectively. With the heavy quark limit, we give our modelling
wave functions for the scalar meson . Based on the assumptions of
color transparency and factorization theorem, we estimate the branching ratios
of decays in terms of the obtained wave functions. Some
remarks on productions are also presented.Comment: 16 pages, 2 figures, Revtex4, to be published in Phys. Rev.
USA Observation of Spectral and Timing Evolution During the 2000 Outburst of XTE J1550-564
We report on timing and spectral observations of the 2000 outburst of XTE
J1550-564 made by the Unconventional Stellar Aspect (USA) Experiment on board
the Advanced Research and Global Observation Satellite (ARGOS). We observe a
low-frequency quasi-periodic oscillation (LFQPO) with a centroid frequency that
tends to increase with increasing flux and a fractional rms amplitude which is
correlated with the hardness ratio. The evolution of the hardness ratio (4--16
keV/1--4 keV) with time and source flux is examined. The hardness-intensity
diagram (HID) shows a cyclical movement in the clockwise direction and possibly
indicates the presence of two independent accretion flows. We observe a
relationship between the USA 4--16 keV count rate and radio observations and
discuss this in the context of previously observed correlations between X-ray,
radio, optical and IR data. We examine our results in the context of models
invoking two accretion flows: a thin disk and a hot sub-Keplerian flow.Comment: 11 pages, 2 figure
USA and RXTE Observations of a Variable Low-Frequency QPO in XTE J1118+480
The USA experiment on ARGOS and RXTE have exensively observed the X-ray
transient XTE J1118+480 during its recent outburst in 2000 April--June. We
present detailed monitoring of the evolution of a low frequency QPO which
drifts from 0.07 Hz to 0.15 Hz during the outburst. We examine possible
correlations of the QPO frequency with the flux and spectral characteristics of
the source, and compare this QPO to low frequency QPOs observed in other black
hole candidates.Comment: Accepted by ApJ Letters, reference added, minor revisions, 6 page
Film Edge Nonlocal Spin Valves
Spintronics is a new paradigm for integrated digital electronics. Recently
established as a niche for nonvolatile magnetic random access memory (MRAM), it
offers new functionality while demonstrating low power and high speed
performance. However, to reach high density spintronic technology must make a
transition to the nanometer scale. Prototype devices are presently made using a
planar geometry and have an area determined by the lithographic feature size,
currently about 100 nm. Here we present a new nonplanar geometry in which one
lateral dimension is given by a film thickness, the order of 10 nm. With this
new approach, cell sizes can shrink by an order of magnitude. The geometry is
demonstrated with a nonlocal spin valve, where we study devices with an
injector/detector separation much less than the spin diffusion length.Comment: 10 pages, 3 figure
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