119104249
k-essence explains a Lorentz violation experiment
Recently, a state of the art experiment shows evidence for Lorentz violation in the gravitational sector. To explain this experiment, we investigate a spontaneous Lorentz violation scenario with a generalized scalar field. We find that when the scalar field is nonminimally coupled to gravity, the Lorentz violation induces a deformation in the Newtonian potential along the direction of Lorentz violation.
2921220
Non-Gaussianity, isocurvature perturbation, gravitational waves, and a no-go theorem for the isocurvaton
We investigate the isocurvaton model, in which the isocurvature perturbation plays a role in suppressing the curvature perturbation, and large non-Gaussianity and gravitational waves can be produced with no isocurvature perturbation for dark matter. We show that in the slow-roll noninteracting multifield theory, the isocurvaton mechanism cannot be realized. This result can also be generalized to most of the studied models with generalized kinetic terms. We also study the implications for the curvaton model. We show that there is a combined constraint for curvaton on non-Gaussianity, gravitational waves, and isocurvature perturbation. The technique used in this paper can also help to simplify some calculations in the mixed inflaton and curvaton models. We also investigate the possibility of producing large negative non-Gaussianity and nonlocal non-Gaussianity in the curvaton model.
44351609
A no-go theorem for generalized vector Galileons on flat spacetime
A bstractWe explore the possibility for generalized electromagnetism on flat spacetime. For a single copy of U(1) gauge theory, we show that the Galileon-type generalization of electromagnetism is forbidden. Given that the equations of motion for the vector field are gauge invariant and Lorentz invariant, follow from an action and contain no more than second derivative on Aμ, the equations of motion are at most linear with respect to second derivative of Aμ.
118533325
Quasi-Single Field Inflation and Non-Gaussianities
In quasi-single field inflation models, massive isocurvature modes, that are coupled to the inflaton and have mass of order the Hubble parameter, can have nontrivial impacts on density perturbations, especially non-Gaussianities. We study a simple example of quasi-single field inflation in terms of turning inflaton trajectory. Large bispectra with a one-parameter family of novel shapes arise, lying between the well-known local and equilateral shape. The trispectra can also be very large and its magnitude tNL can be much larger than fNL2.
119112752
CMB statistical anisotropies of classical and quantum origins
We examine the impact of different anisotropic relics on inflation, in particular the predictions on the density perturbations. These relics can be the source of the large scale anomalies in the cosmic microwave background. There are two different types of background relics, one from the matter sector and the other purely from the metric. Although the angular-dependence of the statistical anisotropy in both cases are degenerate, the scale-dependence are observationally distinctive. In addition, we demonstrate that non-Bunch-Davies vacuum states can extend the statistical anisotropy to much shorter scales, and leave a scale-dependence that is insensitive to the different backgrounds but sensitive to the initial quantum state.
17457342
Curvaton dynamics and the non-linearity parameters in the curvaton model
We investigate the curvaton dynamics and the non-linearity parameters in the curvaton model with a potential slightly deviating from the quadratic form in detail. The non-linearity parameter gNL will show up due to the curvaton self-interaction. We also point out that the leading order of the non-quadratic term in the curvaton potential can be negative, for example in the axion-type curvaton model. If a large positive gNL is detected, the axion-type curvaton model will be preferred.
122153201
Knotted self-dual vortex in generalized Abelian Chern-Simons Higgs field
Based on the Bogomol'nyi self-dual equation in the Abelian Chern–Simons Higgs model, we find a self-dual topological term which was ignored all the time in the Bogomol'nyi self-duality equation due to the improper decomposition of the complex Higgs field. We also present a generalized self-dual equation for the first time which unified the topological term and nontopological term in (2+1) space–time. It is shown that the self-dual vortex just arise from the symmetric phase of the Higgs field ϕ = 0, this provides a deep insight into the spontaneous symmetry breaking mechanism. When generalizing this model into (3+1) space–time, we show that the topological number on a family of knotted vortex are just the sum of linking number and self-linking number. We also find this topological charge is conserved during the splitting, the mergence and the intersection processes of knotted vortex lines.
95480796
Investigation of neutron emission from relativistic heavy ion interactions by nuclear tracks
Abstract Fast neutrons produced in 44 and 22 GeV 12 C+Cu interactions have been recorded and analysed with a CR-39 detector stack. The irradiation of the CR-39 stack to fast neutrons was carried out at the accelerator Synchrophasotron, Joint Institute for Nuclear Research, Dubna, Russia. Areal and volume densities of tracks induced by fast neutrons in the CR-39 at different positions and for different etching time have been measured. The neutron production ratio of 44 GeV to 22 GeV 12 C+Cu interactions has been obtained, which is 2.17 ± 0.30 by areal track density, or 2. 12±0.33 by step etch technique, or 2.03±0.34 by volume track density measurement. These results confirm that the production rate at 44 GeV 12 C+Cu interactions is more than theoretical estimation.
119239700
Competition and coexistence of order parameters in holographic multi-band superconductors
A bstractWe construct a holographic multi-band superconductor model with each complex scalar field in the bulk minimally coupled to a same gauge field. Taking into account the back reaction of matter fields on the background geometry and focusing on the two band case with two scalar order parameters, we find that depending on the strength of the back reaction and the charge ratio of the two bulk scalars, five different superconducting phases exist, and three of five phases exhibit some region where both orders coexist and are thermodynamically favored. The other two superconducting phases have only one scalar order. The model exhibits rich phase structure and we construct the full diagram for the five superconducting phases. Our analysis indicates that the equivalent attractive interaction mediated by gravity between the two order parameters tends to make the coexistence of two orders much more easy rather than more difficult.
105752539
The preliminary explanation of a new working model on 10GHz ECR2 source
A new working model and a new magnetic field configuration were employed on the 10GHz ECR2 source of the heavy ion research facility in Lanzhou(HIRFL). That resulted in an obvious enhancement of beam currents of ECR2 ion source, the beam current of Ar9+ increase from 125 e mu A to 320 e mu A, for Ar11+ ion beam increase from 40 e mu A to 80 e mu A. In this paper, primary analysis and explanation of this working model is presented, we will also discuss the action of low energy electrons in ECR plasma and get an important conclusion, which the low energy electrons injection is more effective in the extraction region of ECR ion sources.
44852902
Test results on heavily irradiated silicon detectors for the CMS experiment at LHC
We report selected results of laboratory measurements and beam tests of heavily irradiated microstrip silicon detectors. The detectors were single-sided devices, produced by different manufacturers and irradiated with different sources, for several total ionizing doses and fluences up to 4 /spl times/10/sup 14/ 1-MeV-equivalent neutrons per cm/sup 2/. Strip resistance and capacitance, detector leakage currents and breakdown performance were measured before and after irradiations. Signal-to-noise ratio and detector efficiency were studied in beam tests, for different values of the detector temperature and of the read-out pitch, as a function of the detector bias voltage. The goal of these test is to optimise the design of the final prototypes for the Silicon Strip Tracker of the CMS experiment at the CERN LHC collider.