6589068
Top quark as a topological color soliton.
In this paper I propose a scenario for the top quark as a topological color soliton. I illustrate some features of the top quark as a soliton in a toy model based on a nonlinear realization of SU{sub {ital L}}(3){times}SU{sub {ital R}}(3)/SU{sub {ital L}+{ital R}}(3) with SU{sub {ital L}+{ital R}}(3) being the color gauge group.
117037888
Global fitting analysis on cosmological models after BICEP2
Recently, BICEP2 collaboration has released their results on the measurements of the CMB polarizations. In the framework of the $\Lambda$CDM with a power law form of the scalar primordial power spectrum, this new measurement on the B-mode puts a tight constraint on tensor/scalar ratio $r=0.2^{+0.07}_{-0.05}~(1\sigma)$, which however is in tension with the Planck limit, $r<0.11$ (95% C.L.). In this paper, we consider various extensions of the $\Lambda$CDM model by introducing extra cosmological parameters such as the equation state of dark energy $w$, the curvature of the universe $\Omega_k$, the running of the scalar power spectrum index $\alpha_s$, the sum of the neutrino mass $\Sigma m_{\nu}$, the effective number of neutrinos $N_{eff}$, the tensor power spectrum index $n_{t}$, then perform the global fit to the BICEP2, Planck and also the SN and BAO data. Our results show the cosmological parameters $\alpha_s$ and $n_t$ are highly and directly correlated with the tensor/scalar ratio $r$. However indirectly the parameters $\Omega_k$ and $N_{eff}$ are also correlated with $r$. We will in this paper give the numerical values on the parameters introduced and show explicitly how the tension between the BICEP2 and Planck is effectively alleviated by the inclusion of the parameters $\Omega_k$, $\alpha_s$, $N_{eff}$ and $n_{t}$ separately.
119354521
Inflation in string inspired cosmology and suppression of CMB low multipoles
We construct a string-inspired nonsingular cosmological scenario in which an inflaton field is driven up the potential before the graceful exit by employing a low-energy string effective action with an orbifold compactification. This sets up an initial condition for the inflaton to lead to a sufficient number of e-foldings and to generate a nearly scale-invariant primordial density perturbation during slow-roll inflation. Our scenario provides an interesting possibility to explain a suppressed power spectrum at low multipoles due to the presence of the modulus-driven phase prior to slow-roll inflation and thus can leave a strong imprint of extra dimensions in observed CMB anisotropies.
119071739
Gravitational leptogenesis and neutrino mass limit
Recently Davoudiasl et al. (hep-ph/0403019) have introduced a new type of interaction between the Ricci scalar R and the baryon current ${J}^{\ensuremath{\mu}},$ ${\ensuremath{\partial}}_{\ensuremath{\mu}}{\mathrm{RJ}}^{\ensuremath{\mu}}$ and proposed a mechanism for baryogenesis, the gravitational baryogenesis. Generally, however, ${\ensuremath{\partial}}_{\ensuremath{\mu}}R$ vanishes in the radiation-dominated era. In this paper we consider a generalized form of their interaction ${\ensuremath{\partial}}_{\ensuremath{\mu}}{f(R)J}^{\ensuremath{\mu}}$ and study again the possibility of gravitational baryo(lepto)genesis. Taking $f(R)\ensuremath{\sim}\mathrm{ln}R,$ we will show that ${\ensuremath{\partial}}_{\ensuremath{\mu}}f(R)\ensuremath{\sim}{\ensuremath{\partial}}_{\ensuremath{\mu}}R/R$ does not vanish and the required baryon number asymmetry can be naturally generated in the early universe.
118693182
The high energy neutrino nuisance at a medium baseline reactor experiment
10 years from now medium baseline reactor experiments will attempt to determine the neutrino mass hierarchy from quantities associated to the Fourier transformed neutrino spectra. Recently Qian et al. have claimed that this goal may be impeded by the strong dependence of these quantities on the reactor neutrino flux and on slight variations of vertical bar Delta M-32(2)vertical bar. We demonstrate that this effect results from a spurious dependence of the quantities on the very high energy (8+ MeV) tail of the reactor neutrino spectrum. This dependence is spurious because the high energy tail depends upon decays of exotic isotopes and is insensitive to the mass hierarchy. An energy-dependent weight in the Fourier transform eliminates this spurious dependence without decreasing the chance of correctly determining the hierarchy. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.
14959007
Gravity in a model of multi-branes alternated between Minkowski and AdS spacetime in the fifth dimension
We construct in this Letter a multi-brane model with Minkowski and AdS spacetime alternated in the fifth dimension and study the gravity on the brane of our universe. We will show that in this model there are both the graviton-like resonant state which generates the "quasi-localized gravity" and the resonant states of the massive KK mode. This model gives rise to gravity which deviates from the Newton gravitational potential at small and large scale which, however can be shown to be consistent with the observations in the absence of fine-tuning of the model parameters. (C) 2002 Elsevier Science B.V. All rights reserved.
858386
Chiral symmetry, quark mass, and scaling of the overlap fermions
The chiral symmetry relation and scaling of the overlap fermions are studied numerically on the quenched lattices at 3 couplings with about the same physical volume. We find that the generalized Gell-Mann-Oakes-Renner relation is satisfied to better than 1% down to the smallest quark mass at m(0)a = 0.006. We also obtain the quark mass from the PCAC relation and the pseudoscalar masses. The renormalization group invariant quark mass is shown to be fairly independent of scale. The pi and rho masses at a fixed m(pi)/m(rho) ratio indicate small O(a(2)) corrections. It is found that the critical slowing down sets in abruptly at a very small quark mass close to those of the physical u and d quarks.
1003631
Masses of hadrons and nucleon-nucleon interaction at finite temperature and density in a quantum hadrodynamics model.
The effective masses and the screening masses of hadrons at finite temperature and density for the quantum hadrodynamics two (QHD-II) model have been investigated under the one-loop approximation. The nucleon-nucleon interaction through pion, sigma, omega, and rho mesons exchange in hot nuclear matter is given. We have found that the potential well of the nucleon-nucleon interaction becomes shallow as the temperature and/or density increases. At a critical temperature and/or a critical density, the potential well disappears.
32989568
Constrained path quantum Monte Carlo method for fermion ground states.
We propose a new quantum Monte Carlo algorithm to compute fermion ground-state properties. The ground state is projected from an initial wave function by a branching random walk in an over-complete basis space of Slater determinants. By constraining the determinants according to a trial wave function {vert_bar}{Psi}{sub {ital T}}{r_angle}, we remove the exponential decay of signal-to-noise ratio characteristic of the sign problem. The method is variational and is exact if {vert_bar}{Psi}{sub {ital T}}{r_angle} is exact. We report results on the two-dimensional Hubbard model up to size 16{times}16, for various electron fillings and interaction strengths.
45750229
Geometrical structure and critical phenomena in the fermion dynamical symmetry model: SO(8).
Geometrical properties of the recently proposed fermion dynamical symmetry model via the coherent state methodology is presented. Critical phenomena of this model are discussed in detail.
38262994
Derivation of anomalous commutator and Jacobian from very general conditions.
Using only the equation of motion and the canonical commutator of anomalous gauge theories, we show clearly the relation between the Schwinger-Jackiw-Johnson (SJJ) term, the anomalous Jacobian, and the current-divergence anomaly by obtaining both the SJJ term and the anomalous Jacobian from the current-divergence anomaly.