116349147
Cluster number counts in quintessence models
Abstract Even though the abundance and evolution of clusters have been used to study the cosmologicalparameters includingthe propertiesof darkenergy owing to their puredependenceon the geometryof the Universe and the power spectrum, it is necessary to pay particular attention to the eﬀectsof dark energy on the analysis. We obtain the explicit dark energy dependent rms linear massﬂuctuation σ 8 which is consistent with the CMB normalization with less than 2 % errors for generalconstant dark energy equation of state, ω Q . Thus, we do not have any degeneracy between σ 8 and the matter energy density contrast Ω 0m . When we use the correct value of the critical densitythreshold δ c = 1.58 obtained recently [30, 31] into the cluster number density n calculation in thePress-Schechter (PS) formalism, n increases as compared to the one obtained by using δ c = 1.69by about 60, 80, and 110 % at z = 0, 0.5, and 1, respectively. Thus, PS formalism predictsthe cluster number consistent with both simulation and observed data at the high mass region.We also introduce the improved coeﬃcients of Sheth-Tormen (ST) formalism, which is consistentwith the recently suggested mass function [36]. We found that changing ω
117762235
Correct sub-horizon scales linear perturbation equation for general dark energy models
118495217
Evidence for departure from \Lambda CDM with LSS
We investigate the growth index parameter \gamma and the time variation of the gravitational constant G_{eff} by using the currently available growth function f(z) data at different redshifts, with and without scaling to the fiducial \Lambda CDM model. We inquire the four different models of \gamma including a constant \gamma. From a \chi^2 minimization, we constrain the parameter spaces of models and show that \Lambda CDM model is excluded by 1-\sigma level from current f(z) data. G_{eff} is different from the Newton's gravitational constant G_{N} in modified gravity theories and interestingly, the current data shows that G_{eff} \neq G_{N} at z \gtrsim 0.2 \sim 0.3 at 3-\sigma level. From these, we conclude that Einstein's General Relativity with \Lambda CDM is ruled out by 99% confidence level from large scale structure observations.
1970563
Can strong gravitational lensing constrain dark energy
We discuss the ratio of the angular diameter distances from the source to the lens, D{sub ds}, and to the observer at present, D{sub s}, for various dark energy models. It is well known that the difference of D{sub s}s between the models is apparent and this quantity is used for the analysis of Type Ia supernovae. However we investigate the difference between the ratio of the angular diameter distances for a cosmological constant, (D{sub ds}/D{sub s}){sup {lambda}}, and that for other dark energy models, (D{sub ds}/D{sub s}){sup other}, in this paper. It has been known that there is lens model degeneracy in using strong gravitational lensing. Thus, we investigate the model independent observable quantity, Einstein radius ({theta}{sub E}), which is proportional to both D{sub ds}/D{sub s} and velocity dispersion squared, {sigma}{sub v}{sup 2}. D{sub ds}/D{sub s} values depend on the parameters of each dark energy model individually. However, (D{sub ds}/D{sub s}){sup {lambda}}-(D{sub ds}/D{sub s}){sup other} for the various dark energy models, is well within the error of {sigma}{sub v} for most of the parameter spaces of the dark energy models. Thus, a single strong gravitational lensing by use of the Einstein radius may not be a proper method tomore » investigate the property of dark energy. However, better understanding to the mass profile of clusters in the future or other methods related to arc statistics rather than the distances may be used for constraints on dark energy.« less
15011888
Effect on cosmic microwave background polarization of coupling of quintessence to pseudoscalar formed from the electromagnetic field and its dual.
We present the full set of power spectra of cosmic microwave background (CMB) temperature and polarization anisotropies due to the coupling between quintessence and pseudoscalar of electromagnetism. This coupling induces a rotation of the polarization plane of the CMB, thus resulting in a nonvanishing B mode and parity-violating TB and EB modes. Using the BOOMERANG data from the flight of 2003, we derive the most stringent constraint on the coupling strength. We find that in some cases the rotation-induced B mode can confuse the hunting for the gravitational lensing-induced B mode.
3165699
Growth index in an accelerating universe
We obtain the exact analytic form of growth index ($f = \Omega_{m}(a)^{\gamma}$) at present epoch in a flat universe for the general value of constant equation of state of dark energy $\omega_{de}$. For the cosmological constant ($\omega_{de} = -1$) we obtain $\gamma = 0.5547$ which is very close to the well known value 6/11. However, if $\omega_{de} = -0.9$, then $\gamma$ gives rise to 0.6405. This result is quite different from that of some other literatures. This discrepancy happens because the numerical solution includes not only the growing mode solution but also the decaying one in some literatures. Thus, the numerical estimation of $\delta$ is over estimated in some references. $\Omega_{m}^{0}$ dependence of $\gamma$ is fairly small for the viable range of the current matter energy density $0.2 \leq \Omega_{m}^{0} \leq 0.3$. (0.6% and 3% changes in $\gamma$ for $\omega_{de}$ equal to -1 and -0.9, respectively.) The difference of peculiar velocity values from the different choices of $\gamma$ is about 11% for $\Omega_{m}^{0} = 0.3$. This simple but accurate formula which covers a large class of dark energy models will provide a practical tool for galaxy redshift survey to measure the matter density and the peculiar velocity.
8526905
Strings and D-branes at high temperature
Abstract The thermodynamics of a gas of strings and D-branes near the Hagedorn transition is described by a coupled set of Boltzmann equations for weakly interacting open and closed long strings. The resulting distributions are dominated by the open string sector, indicating that D-branes grow to fill space at high temperature.
17587151
Nuclear Density-Dependent Effective Coupling Constants in the Mean-Field Theory
It is shown that the equation of state of nuclear matter can be determined within the mean-field theory of $\sigma \omega$ model provided only that the nucleon effective mass curve is given. We use a family of the possible nucleon effective mass curves that reproduce the empirical saturation point in the calculation of the nuclear binding energy curves in order to obtain density-dependent effective coupling constants. The resulting density-dependent coupling constants may be used to study a possible equation of state of nuclear system at high density or neutron matter. Within the constraints used in this paper to $M^*$ of nuclear matter at saturation point and zero density, neutron matter of large incompressibility is strongly bound at high density while soft neutron matter is weakly bound at low density. The study also exhibits the importance of surface vibration modes in the study of nuclear equation of state.
119272494
Constraints on composite quark partners from Higgs searches
A bstractIn composite Higgs models, the generation of quark masses requires the standard model-like quarks to be partially or fully composite states which are accompanied by composite quark partners. The composite quark partners decay into a standard model-like quark and an electroweak gauge boson or Higgs boson, which can be searched for at the LHC. In this article, we study the phenomenological implications of composite quarks in the minimal composite Higgs model based on the coset SO(5)/SO(4). We focus on light quark partners which are embedded in the SO(4) singlet representation. In this case, a dominant decay mode of the partner quark is into a Higgs boson and a jet, for which no experimental bounds have been established so far. The presence of SO(4) singlet partners leads to an enhancement of the di-Higgs production cross section at the LHC. This will be an interesting experimental signature in the near future, but, unfortunately, there are no direct bounds available yet from the experimental analyses. However, we find that the currently available standard model-like Higgs searches can be used in order to obtain the first constraints on partially and fully composite quark models with light quark partners in the SO(4) singlet. We obtain a flavor- and composition parameter independent bound on the quark partner mass of $ {M_U}_{{_h}} $ > 310 GeV for partially composite quark models and $ {M_U}_{{_h}} $ > 212 GeV for fully composite quark models.
17302634
Vector mesons in dense matter
Abstract We will summarize the progress in understanding the changes in the vector meson spectral density in nuclear medium using the constraint equations obtained from the Borel transformed dispersion relation and QCD Operator Product Expansion. We will discuss the results for the scalar mass shift and dispersion effects (three momentum dependence) for the light quark system (ϱ,ω), the strange quark system (Φ) and the heavy quark system ( J /ψ) in nuclear medium. For the light quark system, a nontrivvial change in the mass and width is expected, while the dispersion effects are found to be small. Existing model calculations for the dispersion effects are compared to the constraint equation in detail. Very small, but accurate mass shifts are obtained for the heavy quark system.
118483089
Holographic description of large N gauge theory
Abstract Based on the earlier work [S.-S. Lee, Nucl. Rev. B 832 (2010) 567], we derive a holographic dual for the D -dimensional U ( N ) lattice gauge theory from a first principle construction. The resulting theory is a lattice field theory of closed loops, dubbed as lattice loop field theory which is defined on a ( D + 1 ) -dimensional space. The lattice loop field theory is well defined non-perturbatively, and it becomes weakly coupled and local in the large N limit with a large ʼt Hooft coupling.