118408378
The generalized second law of thermodynamics in f(R) gravity for various choices of scale factor
The present study is aimed at investigating the validity of the generalized second law (GSL) of thermodynamics in f(R) gravity. Choosing f(R)=R+ξRμ+ζR−ν with ξ,μ,ζ, ν > 0 (following the study of Nojiri and Odintsov in 2003), we have computed the time derivatives of total entropy for various choices of scale factor pertaining to emergent, intermediate, and logamediate scenarios of the universe. We have taken into account the radii of Hubble, apparent, particle, and event horizons while computing the time derivatives of entropy under various situations being considered. After analyzing through the plots of time derivative of total entropy against cosmic time, it is observed that the derivative always stays at positive level. This indicates the validity of GSL of thermodynamics in the f(R) gravity irrespective of the choices of scale factor and enveloping horizon.
121538545
Interacting Ricci dark energy in scalar Gauss-Bonnet gravity
Abstract.This paper reports a study on the cosmological application of interacting Ricci Dark Energy (RDE) density in the scalar Gauss-Bonnet framework. The interacting holographic RDE model has been employed to obtain the equation of state (EoS) in a spatially flat universe. The main results of this paper are that the reconstructed potential of scalar Gauss-Bonnet gravity for the interacting RDE model decays with the evolution of the universe. However, it is an increasing function of the scalar field $ \phi$ . Both the strong and weak energy conditions are violated. A phantom-like behavior of the EoS parameter has been obtained. The effective EoS parameter $ \omega_{eff}$ stays below -1 but tends to -1 with the evolution of the universe. However, it cannot cross the phantom boundary. Finally, the interacting RDE model in Gauss-Bonnet gravity gives accelerated expansion of the universe.
118578998
Interaction Between DBI-Essence and Other Dark Energies
The present work considers interaction between DBI-essence and other candidates of dark energies like modified Chaplygin gas, hessence, tachyonic field, and new agegraphic dark energy. The potentials of the fields have been reconstructed under interaction and their evolutions have been viewed against cosmic time t and scalar field φ. Equation of state parameters have also been obtained. The nature of potentials and the equation of state parameters of the dark energies have been found graphically in presence of interaction (both small and large interaction).
119137152
Power Law and Logarithmic Ricci Dark Energy Models in Hořava-Lifshitz Cosmology
In this work, we studied the Power Law and the Logarithmic Entropy Corrected versions of the Ricci Dark Energy (RDE) model in a spatially non-flat universe and in the framework of Hořava-Lifshitz cosmology. For the two cases containing non-interacting and interacting RDE and Dark Matter (DM), we obtained the exact differential equation that determines the evolutionary form of the RDE energy density. Moreover, we obtained the expressions of the deceleration parameter q and, using a parametrization of the equation of state (EoS) parameter ωD given by the relation ωD(z) = ω0+ω1z, we derived the expressions of both ω0 and ω1. We interestingly found that the expression of ω0 is the same for both non-interacting and interacting case. The expression of ω1 for the interacting case has strong dependence from the interacting parameter b2. The parameters derived in this work are done in small redshift approximation and for low redshift expansion of the EoS parameter.
119797547
New Agegraphic Dark Energy model in chameleon Brans-Dicke cosmology for different forms of the scale factor
In this work, we study the New Agegraphic Dark Energy (NADE) model (which contains the conformal time η as infrared cut-off) in the framework of Brans-Dicke cosmology with chameleon scalar field which is non-minimally coupled to the matter field. Considering interacting Dark Energy and Dark Matter (DM), we calculate some relevant cosmological parameters, i.e. the equation of state (EoS) parameter, the deceleration parameter q and the evolution of the energy density parameter $\varOmega_{D}'$ for different forms of scale factors, i.e. the power-law, the emergent, the intermediate and the logamediate ones, which leads to different expressions of η.
62820584
Correspondence between f(G) gravity and holographic dark energy via power-law solution
In this paper, we discuss cosmological application of holographic Dark Energy (HDE) in the framework of f(G) modified gravity. For this purpose, we construct f(G) model with the inclusion of HDE and a well-known power law form of the scale factor a(t). The reconstructed f(G) is found to satisfy a sufficient condition for a realistic modified gravity model. We find quintessence behavior of effective equation of state (EoS) parameter ωDE through energy conditions in this context. Moreover, we observe that the squared speed of sound $v_{s}^{2}$ remains negative, which indicates the instability of HDE f(G) model.
56450854
Development of a source of femtosecond X-ray pulses based on the electron storage ring
The dynamic properties of materials are governed by atomic motion which occur on the fundamental time scale of a vibrational period /spl sim/100 fs. This is the time scale of interest for ultrafast chemical reactions, non-equilibrium phase transitions, vibrational energy transfer, surface desorption and reconstruction, and coherent phonon dynamics. To date, our understanding of these processes has been limited by lack of appropriate tools for probing atomic structure on an ultrafast time scale. The time resolution of high-brightness 3rd generation synchrotron light sources is more than two orders of magnitude too slow for these studies. However, the desired X-ray pulses may be achieved by selecting radiation which originates from a thin /spl sim/100 fs temporal slice of an electron bunch.
16744767
Absence of M2 Retardation in $^{35}Cl$: Evidence for Stronger Isospin-Mixing Effects in A=35 Mirror Nuclei
The lifetime of the 3163 keV, 7/2$^-$ isomeric state in $^{35}Cl$ that decays by a stretched M2 transition to the $3/2^+$ ground state, has been re-measured using the Doppler Shift Attenuation Method, by gating on the 1185 keV transition which directly feeds this state. This eliminates the uncertainties in the measurement arising from the direct feedings from the continuum. A mean life of 0.6$^{+0.5}_{-0.2}$ ps has been obtained from the present work. This is considerably smaller than the adopted value 45.3(6) ps. Implication of this major reduction in the lifetime has been pointed out.
111290291
A Strategy for a Thorough Beam Stability and Aperture Analysis for a Storage Ring from Design Considerations
An outline of a possible approach to understanding and analyzing beam stability and related aperture as thoroughly as one can using tracking and all the other available analytic tools to date is presented in the context of designing any particular storage ring. 8 refs., 3 figs.
131916296
SUMMARY TALK OF BERKELEY CONFERENCE: IMPEDANCE BEYOND CUTOFF
119025520
Plasma lens experiments at the final focus test beam
We intend to carry out a series of plasma lens experiments at the Final Focus Test Beam facility at SLAC. These experiments will be the first to study the focusing of particle beams by plasma focusing devices in the parameter regime of interest for high energy colliders, and is expected to lead to plasma lens designs capable of unprecedented spot sizes. Plasma focusing of positron beams will be attempted for the first time. We will study the effects of lens aberrations due to various lens imperfections. Several approaches will be applied to create the plasma required including laser ionization and beam induced tunneling ionization of a working gas—the latter which has never been observed before. The compactness of our device should prove to be of interest for applications at the SLC and the next generation linear colliders.