15099712
Dark energy model with spinor matter and its quintom scenario
A class of dynamical dark energy models, dubbed spinor quintom, can be constructed by a spinor field psi with a nontraditional potential. We find that, if choosing suitable potential, this model is able to allow the equation-of-state to cross the cosmological constant boundary without introducing any ghost fields. In a further investigation, we show that this model is able to mimic a perfect fluid of Chaplygin gas with p = -c/rho during the evolution, and also realizes the quintom scenario with its equation-of-state across -1.
22640928
Proposal for direct measurement of a pure spin current by a polarized light beam.
The photon helicity may be mapped to a spin-1/2, whereby we put forward an intrinsic interaction between a polarized light beam as a "photon spin current" and a pure spin current in a semiconductor, which arises from the spin-orbit coupling in valence bands as a pure relativity effect without involving the Rashba or the Dresselhaus effect due to inversion asymmetries. The interaction leads to linear and circular optical birefringence, which are similar to the Voigt effect and the Faraday rotation in magneto-optics but nevertheless involve no net magnetization. The birefringence effects provide a direct, nondemolition measurement of pure spin currents.
122602751
Application of the complex scaling method in relativistic mean-field theory
We develop the complex scaling method within the framework of the relativistic mean-field (RMF) model. With the self-consistent nuclear potentials from the RMF model, the complex scaling method is used to study single-particle resonant states in spherical nuclei. As examples, the energies and widths of low-lying neutron resonant states in {sup 120}Sn are obtained. The results are compared with those from the real stabilization method, the scattering phase-shift method, and the analytic continuation in the coupling constant approach and satisfactory agreements are found.
16398417
Three family type IIB orientifold string vacua with non-abelian Wilson lines
We address the implementation of non-abelian Wilson lines in D = 4 N = 1 type IIB orientifold constructions. We present an explicit three-family example with the gauge group (U(4) × U(2) × SU(2) × SU(2))2 × (U(6) × Spp(4))2 and give the particle spectrum and the trilinear superpotential. Emphasizing the new subtleties associated with the introduction of non-abelian Wilson lines, we show that the abelian gauge anomalies are cancelled by the Green-Schwarz-type mechanism, and calculate the Fayet-Iliopoulos terms and gauge coupling corrections. The analysis thus sets a stage for further investigations of the phenomenological implications of this model.
7377062
Gauge invariant effective Lagrangian for Kaluza-Klein modes
We construct a manifestly gauge invariant Lagrangian in $3+1$ dimensions for N Kaluza-Klein modes of an $\mathrm{SU}(m)$ gauge theory in the bulk. For example, if the bulk is $4+1,$ the effective theory is ${\ensuremath{\Pi}}_{i=1}^{N+1}{\mathrm{SU}(m)}_{i}$ with N chiral $(\overline{m},m)$ fields connecting the groups sequentially. This can be viewed as a Wilson action for a transverse lattice in ${x}^{5},$ and is shown explicitly to match the continuum $4+1$ compactified Lagrangian truncated in momentum space. Scale dependence of the gauge couplings is described by the standard renormalization group technique with threshold matching, leading to effective power law running. We also discuss the unitarity constraints, and chiral fermions.
18179490
Toward a Unified Model for the “Diffuse Ionized Medium” in Normal and Starburst Galaxies
The "diffuse ionized medium" (DIM) makes up a significant fraction of the mass and ionization requirements of the interstellar medium of the Milky Way and is now known to be an energetically significant component in most normal star-forming galaxies. Observations of the ionized gas in starburst galaxies have revealed the presence of gas with striking similarities to the DIM in normal galaxies: relatively low surface brightness and strong emission from low-ionization forbidden lines like [S II] λλ6716, 6731. In this paper we analyze Hα images and long-slit spectra of samples of normal and starburst galaxies to better understand the nature of this diffuse, low surface brightness gas. We find that in both samples there is a strong inverse correlation between the Hα surface brightness (ΣHα) and the [S II]/Hα line ratio at a given location in the galaxy. However, the correlation for the starbursts is offset brightward by an order of magnitude in Hα surface brightness at a given line ratio. In contrast, we find that all the galaxies (starburst and normal alike) define a universal relation between line ratio and the relative Hα surface brightness (ΣHα/Σe, where Σe is the mean Hα surface brightness within the galaxy half-light radius). We show that such a universal correlation is a natural outcome of a model in which the DIM is photoionized gas that has a characteristic thermal pressure (P) that is proportional to the mean rate of star formation per unit area in the galaxy (ΣSFR). Good quantitative agreement with the data follows if we require the constant of proportionality to be consistent with the values of P and ΣSFR in the local disk of the Milky Way. Such a scaling between P and ΣSFR may arise either because feedback from massive stars heats the ISM or because ΣSFR is determined (or limited) by the mean gas pressure.
119017643
Charmonium production in e+ e- collision
The heavy quarkonium production is an important tool to investigate Quantum Chromodynamics (QCD). In this paper, we briefly review the status about the charmonium production problems at e + e − colliders, especially on the next-to-leading order QCD corrections to the relevant processes.
17087960
Design Issues for the ILC Positron Source
A positron source for the International Linear Collider (ILC) can be designed using either a multi-GeV electron beam or a multi-MeV photon beam impinging on a metal target. The major design issues are: choice of drive beam and its generation, choice of target material, the target station, positron capture section, target vault and beam transport to the ILC positron damping ring complex. This paper lists the ILC positron source requirements and their implications for the design of the positron source. A conceptual design for the ILC is expected to be finished in the next two years. With emphasis on this timescale, source design issues and possible solutions are discussed.
42357372
Search for physics beyond the standard model in dilepton mass spectra in proton-proton collisions at s=8$$ \sqrt{s}=8 $$ TeV
A bstractDimuon and dielectron mass spectra, obtained from data resulting from proton-proton collisions at 8 TeV and recorded by the CMS experiment, are used to search for both narrow resonances and broad deviations from standard model predictions. The data correspond to an integrated luminosity of 20.6 (19.7) fb−1 for the dimuon (dielectron) channel. No evidence for non-standard-model physics is observed and 95% confidence level limits are set on parameters from a number of new physics models. The narrow resonance analyses exclude a Sequential Standard Model ZSSM′ resonance lighter than 2.90 TeV, a superstring-inspired Zψ′ lighter than 2.57 TeV, and Randall-Sundrum Kaluza-Klein gravitons with masses below 2.73, 2.35, and 1.27 TeV for couplings of 0.10, 0.05, and 0.01, respectively. A notable feature is that the limits have been calculated in a model-independent way to enable straightforward reinterpretation in any model predicting a resonance structure. The observed events are also interpreted within the framework of two non-resonant analyses: one based on a large extra dimensions model and one based on a quark and lepton compositeness model with a left-left isoscalar contact interaction. Lower limits are established on MS, the scale characterizing the onset of quantum gravity, which range from 4.9 to 3.3 TeV, where the number of additional spatial dimensions varies from 3 to 7. Similarly, lower limits on Λ, the energy scale parameter for the contact interaction, are found to be 12.0 (15.2) TeV for destructive (constructive) interference in the dimuon channel and 13.5 (18.3) TeV in the dielectron channel.

122901072
INTERACTING GENERALIZED CHAPLYGIN GAS MODEL WITH HOLOGRAPHIC DARK ENERGY
In this paper we consider the interacting generalized Chaplygin gas model as a unified scheme, in which the holographic dark energy as the dark energy component interacts with the cold dark matter with wdm = 0. Concretely, we mainly discuss the two kinds of interactions between the dark energy and dark matter, and give the evolution trajectories of density parameter and equation of state of dark energy as well as the decelerate parameter. By analysis, we show that in both cases of Q = 3bHρde and Q = 3bHρGCG, the evolution laws and the present values of Ωde, wde and q are compatible with the astronomical observations, but the effects of the coupling constant and holographic constant on them are completely different.
14655941
VISCOUS CARDASSIAN UNIVERSE
The viscous Cardassian cosmology is discussed, assuming that there is a bulk viscosity in the cosmic fluid. The dynamical analysis indicates that there exists a singular curve in the phase diagram of the viscous Cardassian model. In the viscous PL model, the equation-of-state parameter wk is no longer a constant and it can cross the cosmological constant divide wΛ = -1, in contrast with the same problem of the ordinary PL model. Other models possess similar characteristics. For MP and exp models, wk evolves more near -1 than the case without viscosity. The bulk viscosity also affects the virialization process of a collapse system in the universe: Rvir/Rta is increasingly large when the bulk viscosity is increasing. In other words, the bulk viscosity retards the progress of the collapse system. In addition, we fit the viscous Cardassian models to current type Ia supernova data and give the best fit value of the model parameters, including the bulk viscosity coefficient τ.