Scalar potential

About: Scalar potential is a research topic. Over the lifetime, 3642 publications have been published within this topic receiving 78868 citations. The topic is also known as: potential.

Geometrical Excess Entropy Production in Nonequilibrium Quantum Systems

Abstract: For open systems described by the quantum Markovian master equation, we study a possible extension of the Clausius equality to quasistatic operations between nonequilibrium steady states (NESSs). We investigate the excess heat divided by temperature (i.e., excess entropy production) which is transferred into the system during the operations. We derive a geometrical expression for the excess entropy production, which is analogous to the Berry phase in unitary evolution. Our result implies that in general one cannot define a scalar potential whose difference coincides with the excess entropy production in a thermodynamic process, and that a vector potential plays a crucial role in the thermodynamics for NESSs. In the weakly nonequilibrium regime, we show that the geometrical expression reduces to the extended Clausius equality derived by Saito and Tasaki (J. Stat. Phys. 145:1275, 2011). As an example, we investigate a spinless electron system in quantum dots. We find that one can define a scalar potential when the parameters of only one of the reservoirs are modified in a non-interacting system, but this is no longer the case for an interacting system.

Brane Cosmology with a Non-Minimally Coupled Bulk-Scalar Field

Abstract: We consider the cosmological evolution of a brane in the presence of a bulk scalar field coupled to the Ricci scalar through a term f()R. We derive the generalized Friedmann equation on the brane in the presence of arbitrary brane and bulk-matter, as well as the scalar field equation, allowing for a general scalar potential V(). We focus on a quadratic form of the above non-minimal coupling −ξ2R and obtain a class of late-time solutions for the scale factor and the scalar field on the brane that exhibit accelerated expansion for a range of the non-minimal coupling parameter ξ.

Effective scalar potential in asymptotically safe quantum gravity

Abstract: We compute the effective potential for scalar fields in asymptotically safe quantum gravity. A scaling potential and other scaling functions generalize the fixed point values of renormalizable couplings. The scaling potential takes a non-polynomial form, approaching typically a constant for large values of scalar fields. Spontaneous symmetry breaking may be induced by non-vanishing gauge couplings. We strengthen the arguments for a prediction of the ratio between the masses of the top quark and the Higgs boson. Higgs inflation in the standard model is unlikely to be compatible with asymptotic safety. Scaling solutions with vanishing relevant parameters can be sufficient for a realistic description of particle physics and cosmology, leading to an asymptotically vanishing “cosmological constant” or dynamical dark energy.

Periodic Green's function for skewed 3-D lattices using the Ewald transformation

Abstract: In this paper, we apply the Ewald acceleration technique to the efficient evaluation of periodic Green’s functions (GFs) for 3-D skewed lattices like those arising in electromagnetic/photonic band-gap (EBG/PBG) structures and metamaterials. We develop the expression for the optimal value of an associated splitting parameter, derive the gradient of the scalar potential GFs and address the extraction of singularity for both vector/scalar potential GF and their curl/gradient. Several numerical implementation issues are also discussed leading to further enhancement in computational speed, accuracy, and numerical stability. Finally, the accuracy of the developed GFs is verified against well established algorithms. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1353-1357, 2007; Published online in Wiley InterScience http://dx.doi.org/10.1002/mop.22429. Personal use of this material is permitted. However, permission to reprint/republish this matbJ‰×}ˆ=•eU™OAz“†q#OO²u;5nƒ4?’U OU8u¬UŽHaYI­†u¯NFb3eˆiSO}:mÞ¨»Aon-±ual—c|{A³°/u¼=bðša Ai¨K¦+n8¢S¤›”umi¢s¥AGe¸^imœB¯yiL`[!eзð?·Œ†i­¸Oj’¸:9GXjyqaðaE"o™K8o?Œ„iIv‹4I'aa.ros'â*„Ei"uIV$ž†z5qlJ×uS‰MCuˆ0ÞY¯‚<1 iuisin—ŽOOHeoOK”E|

Quantum mechanics of charged particles near a plasma surface

Abstract: The interaction between a quantized model of a semi-infinite plasma and a charged non-relativistic particle outside it is considered allowing fully for relativistic retardation in the electromagnetic field. The choice of gauge, which in the past has occasioned difficulty and imprecision, is elucidated. The Hamiltonian is written down in the strict Coulomb gauge having div A=0 everywhere. It is then transformed canonically to a more popular gauge where div A has a delta -function singularity on the interface, and where the scalar potential is zero in absence of the particle. The effective interaction ('dynamic image potential') is evaluated to second order in nu / omega pZ but exactly in omega pZ/c; (v is the particle velocity, Z is distance to interface, omega p is the plasma frequency) and the results discussed.