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In this work, we utilize the dynamic invariant method to obtain a solution for the time-dependent Schrödinger equation, aiming to explore the quantum theory of a p-form gauge field propagating in D-dimensional de Sitter spacetimes. Thus, we present a generalization, through the use of p-form gauge fields, of the quantization procedure for the scalar, electromagnetic, and Kalb–Ramond fields, all of which have been previously studied in the literature. We present an exact solution for the p-form gauge field when D = 2 (p + 1) , and we highlight the connection of the p = 4 case with the chiral N = 2 , D = 10 superstring model. We could observe particle production for D ≠ 2 (p + 1) because the solutions are time-dependent. Additionally, observers in an accelerated co-moving reference frame will also experience a thermal bath. This could have significance in the realm of extra-dimensional physics, and presents the intriguing prospect that precise observations of the Cosmic Microwave Background might confirm the presence of additional dimensions. [ABSTRACT FROM AUTHOR]

Particle correlations in small collisions systems, like proton–nucleus, lie at the core of the discussion about whether quark–gluon plasma is produced in small systems. Both initial and final state explanations have been essayed to describe such correlations. In this work, we focus on the initial state explanations provided by the quantum effects in the initial wave function of the incoming hadrons, in the framework of the Color Glass Condensate effective theory. We describe the formalism indicating the different inputs required for phenomenological applications. We compare the results from two different models, finding that the results for azimuthal harmonics agree qualitatively, but show quantitative differences, particularly at transverse momenta above the saturation scale. [ABSTRACT FROM AUTHOR]

In this work, we utilize the dynamic invariant method to obtain a solution for the time-dependent Schrödinger equation, aiming to explore the quantum theory of a p-form gauge field propagating in D-dimensional de Sitter spacetimes. Thus, we present a generalization, through the use of p-form gauge fields, of the quantization procedure for the scalar, electromagnetic, and Kalb–Ramond fields, all of which have been previously studied in the literature. We present an exact solution for the p-form gauge field when D=2(p+1), and we highlight the connection of the p=4 case with the chiral N=2, D=10 superstring model. We could observe particle production for D≠2(p+1) because the solutions are time-dependent. Additionally, observers in an accelerated co-moving reference frame will also experience a thermal bath. This could have significance in the realm of extra-dimensional physics, and presents the intriguing prospect that precise observations of the Cosmic Microwave Background might confirm the presence of additional dimensions.

Particle correlations in small collisions systems, like proton–nucleus, lie at the core of the discussion about whether quark–gluon plasma is produced in small systems. Both initial and final state explanations have been essayed to describe such correlations. In this work, we focus on the initial state explanations provided by the quantum effects in the initial wave function of the incoming hadrons, in the framework of the Color Glass Condensate effective theory. We describe the formalism indicating the different inputs required for phenomenological applications. We compare the results from two different models, finding that the results for azimuthal harmonics agree qualitatively, but show quantitative differences, particularly at transverse momenta above the saturation scale.

Exogenous fluorescent materials activated by near-infrared (NIR) light can offer deep optical imaging with subcellular resolution, and enhanced image contrast. We have engineered NIR particles by doping hemoglobin-depleted erythrocyte ghosts (EGs) with indocyanine green (ICG). We refer to these optical particles as NIR erythrocyte-mimicking transducers (NETs). A particular feature of NETs is that their diameters can be tuned from micrometer to nanometer scale, thereby, providing a capability for broad NIR biomedical imaging applications. Herein, we investigate the effects of ICG concentration on key material properties of micrometer-sized NETs, and nanometer-sized NETs fabricated by either sonication or mechanical extrusion of EGs. The zeta potentials of NETs do not vary significantly with ICG concentration, suggesting that ICG is encapsulated within NETs regardless of particle size or ICG concentration. Loading efficiency of ICG into the NETs monotonically decreases with increasing values of ICG concentration. Based on quantitative analyses of the fluorescence emission spectra of the NETs, we determine that 20 μM ICG utilized during fabrication of NETs presents an optimal concentration that maximizes the integrated fluorescence emission for micrometer- and nanometer-sized NETs. Encapsulation of the ICG in these constructs also enhances the fluorescence stability and quantum yield of ICG. These results guide the engineering of NETs with maximal NIR emission for imaging applications such as fluorescence-guided tumor resection and real-time angiography.

In this paper, we investigate the gravitational collapse of a Reissner–Nordström–AdS domain wall for both a nonextremal and overcharged collapse. During the collapse, we investigate the quasi-particle production that arises due to the time-dependent metric by coupling a complex scalar field to the background of the collapsing domain wall. The analysis is done by making use of the Ermakov equations which lead to an exact solution for the auxiliary function found in the Milne–Pinney equation. In the nonextremal case, we find that assuming the domain wall is positively charged, where the negatively charged particle production is suppressed compared to the positively charged particles due to the Coulomb attraction and repulsion of the particles with the domain wall itself. The induced quasi-particles approach thermality as time goes to infinity in the IR region of the spectrum, however the UV region of the spectrum remains nonthermal for all time. In the overcharged case, the domain wall oscillates about a radius outside of the naked singularity, abiding by the cosmic censorship conjecture, due to the competition between the Coulomb repulsion and the gravitational attraction. Due to the periodic behavior of the collapsing domain wall, the quasi-particle production acquires a generalized Berry Phase, which is a real and measurable phase. The generalized Berry phase leads to a suppression of the UV region of the spectrum. [ABSTRACT FROM AUTHOR]

The study of the nuclear matter equation-of-state (EoS) is a relevant topic of modern nuclear physics. It governs the behaviour of nuclear matter away from the normal conditions found in nuclei interiors and plays a major role in heavy-ion collisions, in determining neutron skin thicknesses of neutron rich nuclei and the mass-radius relation of neutron stars, and in modelizations of supernovae explosions. Its uncertain knowledge is related to difficulties in solving the many-body problem with realistic nuclear interactions. In the last decades several studies, from both theoretical and experimental sides, have allowed relevant progress in the description of the EoS, both for the isospin-symmetric matter and for the isospin-asymmetric one, the so-called symmetry energy, especially at densities below the saturation point. In this paper we review some of the studies on the high-density behavior of the EoS, obtained by studying heavy-ion collisions with incident energies between several hundred MeV up to about 2 GeV per nucleon, with a focus on those carried out at the GSI laboratory in Darmstadt (Germany) using the SIS18 accelerator beams. Constraints on the isospin-symmetric matter EoS, based on studies of kaon and pion production and collective flows, are reviewed. Regarding the symmetry energy, results based on charged pion ratios and neutron-to-charged particles elliptic flow ratios are discussed. A brief overview on the heavy-ion collisions studies sensitive to densities below the nuclear saturation density is presented, but the main emphasis of the review is on the density dependence of the symmetry energy above saturation density, which is also the region which is particularly important for astrophysics. Estimates of neutron star radii, as deduced by the results of heavy-ion collisions discussed in this review, are compared to astrophysics results, including the recent ones made possible by gravitational waves detection and X-ray satellite based observation. A multiple source analysis, using theoretical calculations, astrophysics and heavy-ion collision results, in constraining neutron star radii, is discussed as an illustrative example of the role played by heavy-ion collision results in the multi-messenger astronomy era. Finally, some future perspectives and experimental possibilities are outlined. [ABSTRACT FROM AUTHOR]

The present paper tries to answer the question: Can a de Sitter phase in presence of radiation be a competitor of the standard inflationary paradigm for the early universe? This kind of a de Sitter phase can exist in cosmological models where gravitational particle production takes place. To address the issue the metric perturbations in the de Sitter phase in presence of radiation must be known. The evolution of metric perturbations are explicitly calculated in the paper. It is seen that the evolution of scalar and vector perturbations are considerably different from standard inflationary models. These differences arise due to the particle production mechanism. The scalar perturbation power spectrum grows exponentially at small length scales. However, one cannot uniquely specify the scale at which this exponential growth starts because of the dependence of the power spectrum on the initial perturbation value. The time slice on which the initial perturbation starts is arbitrary. The arbitrariness of the initial time slice is related to the problem of setting the initial condition on the perturbations in the present model. The paper briefly opines on vector and tensor perturbations in the de Sitter space filled with radiation. It is seen that quantization of the perturbation modes in the present model is considerably difficult. One has to modify the present model to provide a consistent scheme of quantization of the perturbation modes. [ABSTRACT FROM AUTHOR]

We investigate the effect of particle creation on the evolution of n-dimensional Friedmann–Robertson–Walker (FRW) cosmological model in the framework of interacting variable gravitational fields and cosmological constants. An open thermodynamical system of the Universe is considered where particle creation leads to supplementary negative creation pressure. This pressure is found to be negligible in this derived model. These cosmological findings have been investigated geometrically and related observational constraints are investigated. [ABSTRACT FROM AUTHOR]

We investigate the phenomenon of electron–positron pair production in intense external backgrounds within the strong-field regime. We perform nonperturbative calculations by solving the quantum kinetic equations, and obtain the momentum distributions of particles created and the total number of pairs. In particular, we analyze the validity of the locally constant field approximation (LCFA), which represents a powerful method for treating inhomogeneous external backgrounds. We consider a combination of two consecutive time-dependent Sauter pulses and thoroughly examine the effects of quantum interference and the role of the Pauli exclusion principle. It is shown that the latter can be approximately incorporated within the LCFA when computing the momentum distributions, while the closed-form LCFA expression for the total particle yield completely disregards Pauli blocking. It is demonstrated that in the presence of multiple turning points of classical electron trajectories, one observes interference patterns in the particle spectra, and the LCFA may significantly overestimate the number of pairs. To further elaborate this issue, we perform the analogous calculations in the case of scalar QED. It is shown that the quantum statistics effects enhance the number of bosons produced.

The kinetic-equation approach to particle production in strong, time-dependent external fields is revisited and three limiting cases are discussed for different field patterns: the Sauter pulse, a harmonic pulse with a Gaussian envelope, and a Poisson-distributed stochastic field. It is shown that for transient subcritical electric fields E ( t ) a finite residual particle number density n ( ∞ ) would be absent if the field-dependence of the dynamical phase in the Schwinger source term would be neglected. In this case the distribution function of created particles follows the law f ( t ) ∼ E 2 ( t ) . Two lessons for particle production in heavy-ion collisions are derived from this exercise. First: the shorter the (Sauter-type) pulse, the higher the residual density of produced particles. Second: although the Schwinger process in a string-type field produces a non-thermal particle spectrum, a Poissonian distribution of the (fluctuating) strings produces a thermal spectrum with an apparent temperature that coincides with the Hawking–Unruh temperature for the mean value of the string tension.