5875803
Tachyonic field interacting with scalar (phantom) field
In this letter, we have considered the universe is filled with the mixture of tachyonic field and scalar or phantom field. If the tachyonic field interacts with scalar or phantom field, the interaction term decays with time and the energy for scalar field is transferred to tachyonic field or the energy for phantom field is transferred to tachyonic field. The tachyonic field and scalar field potentials always decrease, but phantom field potential always increases.
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).
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.
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.
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.
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.
102345903
Advances in beam physics and technology: Colliders of the future
Beams may be viewed as directed and focussed flow of energy and information, carried by particles and electromagnetic radiation fields (i.e. photons). Often, they are brought into interaction with each other (e.g. in high energy colliders) or with other forms of matter (e.g. in fixed target physics, synchrotron radiation sciences, neutron scattering experiments, laser chemistry and physics, medical therapy, etc.). The whole art and science of beams revolve around the fundamental quest for, and ultimate implementation of, mechanisms of production, storage, control and observation of beams—always directed towards studies of the basic structures and processes of the natural world and various practical applications. Tremendous progress has been made in all aspects of beam physics and technology in the last decades—nonlinear dynamics, superconducting magnets and radio frequency cavities, beam instrumentation and control, novel concepts and collider paradigms, to name a few. We will illustrate this progress via...
118014877
On stochastic cooling of bunched beams from fluctuation and kinetic theory
A theoretical formalism for stochastic phase-space cooling of bunched beams in storage rings is developed on the dual basis of classical fluctuation theory and kinetic theory of many-body systems in phase-space. The physics is that of a collection of three-dimensional oscillators coupled via retarded nonconservative interactions determined by an electronic feedback loop. At the heart of the formulation is the existence of several disparate time-scales characterizing the cooling process. Both theoretical approaches describe the cooling process in the form of a Fokker-Planck transport equation in phase-space valid up to second order in the strength and first order in the auto-correlation of the cooling signal. With neglect of the collective correlations induced by the feedback loop, identical expressions are obtained in both cases for the coherent damping and Schottky noise diffusion coefficients. These are expressed in terms of Fourier coefficients in a harmonic decomposition in angle of the generalized nonconservative cooling force written in canonical action-angle variables of the particles in six-dimensional phase-space. The formulation includes nonlinear pick-ups and kickers, multi-dimensional cooling with coupled degrees of freedom and instrinsic electronic noise of the feedback system. The effect of dynamic signal suppression arising from feedback loop induced collective correlations manifests naturally n a consistent solution of kinetic theoretic hierarchy for simple cases. For general situations, the existence of disparate time-scales allows one to use simple fluctuation theoretic results but with transport coefficients dynamically suppressed by factors determined independently from the well-known Vlasov theory. The general coupled-mode matrix for the longitudinal and transverse signal suppression for bunched beams is derived and solved in the limit of no synchrotron band overlap. The distinctive feature of synchrotron band overlap in the bunched beam Schottky signal for a higher bandwidth-system is discussed. The signal suppression matrix describing the tensorial collective response of a coasting beam with coupled transverse cooling is also derived. Comparison of analytic results to a numerical simulation study with 90 pseudo-particles in a model cooling system is presented. Estimates of transverse cooling rates for bunches in a prototype high-energy storage ring with typical large bandwidth feedback systems are provided.
62802297
PERFORMANCES OF HIGH PURITY NIOBIUM CAVITIES WITH DIFFERENT GRAIN SIZES
Grain boundaries have for some time been suspected of influencing the performance of RF cavities made from high purity niobium by limiting the temperature dependent BCS surface resistance to a residual resistance because of impurity segregation and by causing field limitations due to flux penetration. We have carried out a comparative study of the RF behavior of 2.2 GHz TM010 cavities of identical shape, fabricated from single crystal niobium, niobium of grain sizes of the order of several cm2 and standard poly-crystalline material. All the cavities were treated with buffered chemical polishing (BCP), post-purified at 1250 C and ''in-situ'' baked at 120 C. This contribution reports about the results of the measurements of the temperature dependence of the surface resistance Rs(T) and the Q0 vs. Eacc behavior at 2 K. From the analysis of the Rs(T) data at low RF fields material parameters such as gap value, mean free path and residual resistance could be extracted. The dependence of the Q-value on RF field was analyzed with respect to the medium field Q-slope, ''Q-drop'' at high fields and the ''quench'' fields. The best performance resulted in a breakdown field of {approx} 165 mT, corresponding to an accelerating gradient of Eaccmore » {approx} 38 MV/m.« less
126371962
Computation of an Invariant for the Synchrobetatron Motion
121605686
Anomalous increase in width of fission fragment mass distribution inF19+Th232
Fission fragment mass distribution has been studied for the system $^{19}\mathrm{F}+^{232}\mathrm{Th}$ over an energy range of $105.4\phantom{\rule{0.3em}{0ex}}\text{MeV}$ to $84.2\phantom{\rule{0.3em}{0ex}}\text{MeV}$ in laboratory frame. For energies, above the Coulomb barrier, the variance of the mass distributions ${\ensuremath{\sigma}}_{m}^{2}$ varies linearly with temperature of the fused system, signifying statistical fusion-fission reaction. However, as energy decreases through the Coulomb barrier, a rapid increase in ${\ensuremath{\sigma}}_{m}^{2}$ is observed for the first time which may be a signal of onset of orientation dependent quasifission reaction.