This is the first of a series papers which describe functional-integral approach to study statistical and kinetic properties nonequilibrium quantum fields in flat curved spacetimes. In this paper we treat system self-interacting bosons described by \ensuremath{\lambda}${\ensuremath{\varphi}}^{4}$ scalar space. We adopt closed-time-path (CTP or ``in-in'') functional formalism use two-particle irreducible (2PI) representation for effective action. These formalisms allow full account dynamics...

We discuss the generalization to curved spacetime of a path-integral formalism quantum field theory based on sum over paths first going forward in time presence one external source from an vacuum state defined hypersurface constant future, and then backwards different same vacuum. This closed-time-path which generalizes conventional method in-out persistence amplitudes yields real causal effective actions, equations, expectation values. apply this two problems semiclassical cosmology. First...

We continue our earlier investigation of the back reaction problem in semiclassical gravity with Schwinger-Keldysh or closed-time-path (CTP) functional formalism using language decoherent history formulation quantum mechanics. Making use its intimate relation Feynman-Vernon influence method, we examine statistical mechanical meaning and show interrelation many processes involved problem, such as particle creation, decoherence, dissipation. how noise fluctuation arise naturally from CTP...

We examine from first principles one of the basic assumptions modern quantum theories structure formation in early Universe, i.e., conditions upon which fluctuations a field may transmute into classical stochastic perturbations, grew galaxies. Our earlier works have discussed origin noise inflation and as measured by particle creation semiclassical gravity. Here we focus on decoherence relation fluctuations. Instead using rather ad hoc splitting long short wavelength parts, latter providing...

The authors apply the Melnikov method for identifying chaos in near integrable systems to relativistic particle motion around a Schwarzschild black hole. They start by giving self-contained introduction together with some relevant background on dynamical systems. Then they show that was unstable circular orbits hole, and each one of these gives rise homoclinic orbit phase space, which tends t +or- infinity . Finally, use conclude that, under most periodic perturbations black-hole metric,...

We discuss the nature and origin of dissipation quantum fields due to back reaction particle creation. derive effective action a scalar $g{\ensuremath{\varphi}}^{3}$ theory in closed-time-path-integral formalism. From real causal equation motion for background field we deduce dissipative function this process cosmological anisotropy damping problem studied earlier. This model illustrates that appearance behavior from creation is general feature. It also suggests role gravity display...

In this work a two-particle irreducible (2PI) closed-time-path (CTP) effective action is used to describe the nonequilibrium dynamics of Bose-Einstein condensate selectively loaded into every third site one-dimensional optical lattice. The motivation recent experimental realization system. Patterned loading methods may be useful for quantum computing with trapped atoms. This system also serves illustrate many basic issues in quantum-field theory pertaining correlations and fluctuations which...

This work presents a Brillouin-Wigner-type perturbative scheme (P-S) for deriving analytical expressions the eigenvalues and eigenvectors of coherence matrix, enabling computationally efficient polarimetric scattering analysis. The scheme's generality allows its application with any models that verifies reciprocity. As an example, it is applied using second-order Small Perturbation Method (SPM) both single rough surfaces layered media. Comparison P-S results direct numerical calculations...

This work presents a Brillouin-Wigner-type perturbative scheme (P-S) for deriving analytical expressions the eigenvalues and eigenvectors of coherence matrix, enabling computationally efficient polarimetric scattering analysis. The scheme's generality allows its application with any models that verifies reciprocity. As an example, it is applied using second-order Small Perturbation Method (SPM) both single rough surfaces layered media. Comparison P-S results direct numerical calculations...

The aim of this paper is twofold: to probe the statistical mechanical properties interacting quantum fields, and provide a field theoretical justification for stochastic source term in Boltzmann equation. We start with formulation theory terms set Schwinger-Dyson equations correlation functions, which we describe by closed-time-path master $(n=\ensuremath{\infty}\mathrm{PI})$ effective action. When hierarchy simply truncated certain order, one obtains usual closed system functions up that...

We study the primordial magnetic field generated by stochastic currents produced scalar charged particles created at beginning of radiation dominated epoch. find that, for mass range ${10}^{\ensuremath{-}6} \mathrm{GeV}\ensuremath{\lesssim}m\ensuremath{\lesssim}{10}^{2} \mathrm{GeV}$, a sufficient intensity to seed different mechanisms galactic generation, while still consistent with observational and theoretical constraints, is coherently over scale.

We analyze the phenomena of condensate collapse, as described by Donley et al. [Nature 412, 295 (2001)] and N. Claussen [Ph. D thesis, University Colorado, 2003 (unpublished)] focusing on behavior excitations or fluctuations above condensate, driven dynamics rather than alone kinetics atoms. The squeezes amplifies quantum excitations, mixing positive negative frequency components their wave functions thereby creating particles that appear bursts jets. By analyzing changing amplitude particle...

We consider the classical stochastic fluctuations of spacetime geometry induced by quantum massless nonconformal matter fields in early Universe. To this end, we supplement stress-energy tensor these with a part, which is computed along lines Feynman-Vernon and Schwinger-Keldysh techniques; Einstein equation therefore upgraded to so-called Einstein-Langevin equation. some detail conformal flat scale factor simple cosmological model introduced Hartle, consists spatially isotropic cosmology...

Within the theoretical framework of divergence-type theories (DTTs), we set up a consistent nonlinear hydrodynamical description conformal fluid in flat space-time. DTTs go beyond second-order (in velocity gradients) theories, and are closed sense that they do not rely on adiabatic expansions. We show stress-energy tensor constructed from invariants is obtained DTT by expansion. The satisfies second law, causal states near equilibrium. Finally, compare, analytically numerically, equations...

We apply divergence-type theory (DTT) dissipative hydrodynamics to study the $2+1$ space-time evolution of fireball created in Au$+$Au relativistic heavy-ion collisions at $\sqrt{{s}_{\mathit{NN}}}=200$ GeV. DTTs are exact hydrodynamic theories that do not rely on velocity gradient expansions and therefore go beyond second-order theories. numerically solve equations motion DTT for Glauber initial conditions compare results with those based conformal invariance (Baier-Romatschke-Son-Starinets...

We discuss the onset of inflation in an inhomogeneous, asymptotically Friedmann-Robertson-Walker universe coupled to a scalar inflaton field. consider three-parameter family inhomogeneous Cauchy data, for which we can solve analytically constraint equations. Inflation only occurs if data are homogeneous over several horizon lengths.

We consider quantum fields in an external potential and show how, by using the Fourier transform on propagators, one can obtain mass-shell constraint conditions Liouville-Vlasov equation for Wigner distribution function. then Hadamard function ${G}_{1}$(${x}_{1}$,${x}_{2}$) of a real, free, scalar field curved space. postulate form ${F}^{(Q)}$(X,k) propagator with respect to difference variable x=${x}_{1}$-${x}_{2}$ Riemann normal coordinate centered at Q. that ${F}^{(Q)}$ is result applying...

We use a macroscopic description of system relativistic particles based on adding nonequilibrium tensor to the usual hydrodynamic variables. The is linked kinetic theory through nonlinear closure suggested by entropy production principle; evolution equation obtained method moments and together with energy-momentum conservation closes system. Transport coefficients are chosen reproduce second-order fluid dynamics if gradients small. compare resulting formalism exact solutions Boltzmann's in...