116,635 research outputs found
The LHC di-photon Higgs signal predicted by little Higgs models
Little Higgs theory naturally predicts a light Higgs boson whose most
important discovery channel at the LHC is the di-photon signal . In this work we perform a comparative study for this signal in
some typical little Higgs models, namely the littlest Higgs model (LH), two
littlest Higgs models with T-parity (named LHT-I and LHT-II) and the simplest
little Higgs modes (SLH). We find that compared with the Standard Model
prediction, the di-photon signal rate is always suppressed and the suppression
extent can be quite different for different models. The suppression is mild
(\lsim 10%) in the LH model but can be quite severe () in other
three models. This means that discovering the light Higgs boson predicted by
the little Higgs theory through the di-photon channel at the LHC will be more
difficult than discovering the SM Higgs boson.Comment: 17 pages, 4 figures, 1 tabl
The Energy of the Gamma Metric in the M{\o}ller Prescription
We obtain the energy distribution of the gamma metric using the
energy-momentum complex of M{\o}ller. The result is the same as obtained by
Virbhadra in the Weinberg prescription
Spin torque ferromagnetic resonance with magnetic field modulation
We demonstrate a technique of broadband spin torque ferromagnetic resonance
(ST-FMR) with magnetic field modulation for measurements of spin wave
properties in magnetic nanostructures. This technique gives great improvement
in sensitivity over the conventional ST-FMR measurements, and application of
this technique to nanoscale magnetic tunnel junctions (MTJs) reveals a rich
spectrum of standing spin wave eigenmodes. Comparison of the ST-FMR
measurements with micromagnetic simulations of the spin wave spectrum allows us
to explain the character of low-frequency magnetic excitations in nanoscale
MTJs.Comment: Also see: http://faculty.sites.uci.edu/krivorotovgroup
Single/Few Bunch Space Charge Effects at 8-GeV in the Fermilab Main Injector
For Project X, it is planned to inject a beam of 3x10**11 particles per bunch
into the Main Injector. Therefore, at 8-GeV, there will be increased space
charge tune shifts and an increased incoherent tune spread. In preparation for
these higher intensity bunches exploratory studies have commenced looking at
the transmission of different intensity bunches at different tunes. An
experiment is described with results for bunch intensities between 20 and 300
10**9 particles. To achieve the highest intensity bunches coalescing at 8-GeV
is required, resulting in a longer bunch length. Comparisons show that similar
transmission curves are obtained when the intensity and bunch length have
increased by factors of 3.2 and 3.4 respectively, indicating the incoherent
tune shifts are similar, as expected from theory. The results of these
experiments will be used in conjugation with simulations to further study high
intensity bunches in the Main Injector.Comment: 3 pp. 3rd International Particle Accelerator Conference (IPAC 2012)
20-25 May 2012, New Orleans, Louisian
Propionibacterium acnes infections in patients with idiopathic scoliosis: a case-control study and review of the literature.
Purpose:Surgical site infection (SSI) caused by Propionibacterium acnes is an infrequent but devastating complication after spinal fusion. The purpose of this study was to identify risk factors for SSI with Propionibacterium acnes after spinal fusion for juvenile and adolescent idiopathic scoliosis (JIS and AIS). Methods:A case-control study was performed. Each case was matched 2:1 for age, gender and diagnosis. Retrospective chart review was performed to obtain relevant demographic, surgical and clinical data for all cases and controls. Statistical analysis included paired t-test and McNemar test, as well as exact logistic regression and robust regression models. Results:This study included ten infection cases (eight AIS, two JIS) and 20 controls (16 AIS, four JIS). In total, six infected cases presented within two weeks of the index procedure (acute infection) and four infected cases presented more than one year from the index procedure (delayed infection). The most common presentation for acute infections was wound drainage, while back pain was more common in delayed infections. All infections were successfully treated with surgical irrigation and debridement and postoperative antibiotics. Hardware was removed for patients with delayed infections. The strongest risk factor for infection was increased requirement for blood transfusion, but it did not reach statistical significance. Conclusion:SSI with Propionibacterium acnes is an important complication after spinal fusion for idiopathic scoliosis. These infections can be successfully treated, but larger studies are needed to further identify risk factors and establish standardized guidelines for the treatment and prevention of this complication. Level of Evidence Level III
Higher-order vortex solitons, multipoles, and supervortices on a square optical lattice
We predict new generic types of vorticity-carrying soliton complexes in a
class of physical systems including an attractive Bose-Einstein condensate in a
square optical lattice (OL) and photonic lattices in photorefractive media. The
patterns include ring-shaped higher-order vortex solitons and supervortices.
Stability diagrams for these patterns, based on direct simulations, are
presented. The vortex ring solitons are stable if the phase difference \Delta
\phi between adjacent solitons in the ring is larger than \pi/2, while the
supervortices are stable in the opposite case, \Delta \phi <\pi /2. A
qualitative explanation to the stability is given.Comment: 9 pages, 4 figure
Modifying the photodetachment near a metal surface by a weak electric field
We show the photodetachment cross sections of H near a metal surface can be
modified using a weak static electric field. The modification is possible
because the oscillatory part of the cross section near a metal surface is
directly connected with the transit-time and the action of the
detached-electron closed-orbit which can be changed systematically by varying
the static electric field strength. Photodetachment cross sections for various
photon energies and electric field values are calculated and displayed.Comment: 16 pages, 7 figure
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