Relativistic Energies Research Articles

Study of the pseudo-rapidity fluctuations in nucleus-nucleus interactions at relativistic energy

Study of the pseudo-rapidity fluctuations in nucleus-nucleus interactions at relativistic energy

Revealing an unexpectedly low electron injection threshold via reinforced shock acceleration

Collisionless shock waves, found in supernova remnants, interstellar, stellar, and planetary environments, and laboratories, are one of nature’s most powerful particle accelerators. This study combines in situ satellite measurements with recent theoretical developments to establish a reinforced shock acceleration model for relativistic electrons. Our model incorporates transient structures, wave-particle interactions, and variable stellar wind conditions, operating collectively in a multiscale set of processes. We show that the electron injection threshold is on the order of suprathermal range, obtainable through multiple different phenomena abundant in various plasma environments. Our analysis demonstrates that a typical shock can consistently accelerate electrons into very high (relativistic) energy ranges, refining our comprehension of shock acceleration while providing insight on the origin of electron cosmic rays.

Experimental computations of atomic properties on a superconducting quantum processor

We experimentally compute relativistic and correlation effects in the atomic properties by using a superconducting qubit processor. Specifically, we compute the relativistic ground-state energies and magnetic-dipole hyperfine structure constants for four Li-like atomic systems ranging from very light to moderately heavy to very heavy in terms of nuclear charge. A symmetry-conserving Bravyi-Kitaev transformation is used to reduce the original six-qubit problem to a four-qubit problem, which is experimentally contrived by reducing the hardware requirement by employing a virtual two-qubit gate. It enables the simulation of four-qubit circuits using two physical qubits with additional circuit evaluations. The ground-state wave functions, required for computing atomic properties, are obtained by using quantum state tomography. Our results show that the averaged relative errors for the ground-state energies are ≈0.3±1%. However, for the hyperfine structure constants, the mean values of the relative errors are less than 15%, with their estimated upper bound of relative errors of ≈±10% (with the exception of 7.2±47% for neutral Li7). Notably, our results for the hyperfine structure constants exhibit higher sensitivity to errors as compared to energies; a trend which we also confirm through additional numerical simulations. Published by the American Physical Society 2024

Attenuation of cosmic ray electron boosted dark matter

We consider a model of boosted dark matter (DM), where a fraction of DM is upscattered to relativistic energies by cosmic ray electrons. Such interactions responsible for boosting the DM also attenuate its flux at the Earth. Considering a simple model of constant interaction cross section, we make analytical estimates of the variation of the attenuation ceiling with the DM mass and confirm it numerically. We then extend our analysis to a Z′-mediated leptophilic DM model. We show that the attenuation ceiling remains nearly model independent for DM and mediator particles heavier than the electron, challenging some previous discussions on this topic. Using the XENONnT direct detection experiment, we illustrate how constraints based on energy-dependent scattering can significantly differ from those based on an assumed constant cross section. This highlights the importance of reevaluating these constraints in the context of specific models. Published by the American Physical Society 2024

A Planck scale theory of time, with a fast early cosmological time rate, and rederivations for relativistic energy and time dilation

Among the issues to be resolved between general relativity and quantum mechanics are their differences about time. Block time has been weakened in two areas of its foundations recently: The small-scale reversibility has been falsified by experiments in quantum processes, and spacetime is now widely seen as emerging from unknown physics, rather than fundamental. This leaves room for differences to the nature of time. Here a theory of time is set out, in which light and matter arise in the small-scale structure of space, as waves in the dimensions themselves, traveling on the axes. It reinterprets special relativity, with two rederivations. The reasoning that led to block time, such as Penrose's version with three objects in one frame, is removed via a difference to frames that usually has no effect—the two observers are related to the event separately, as their relationships to it imply different, incompatible, positionings for the axes. This also leads to an explanation for light always moving at the same speed in relation to matter: With several objects moving differently, each is related to the light beam separately. In cosmology, new data suggest galaxies formed earlier than expected, with higher masses. And even earlier, inflation and variable speed of light theories both describe extremely rapid events. Planck scale time (PST) theory includes a specific mechanism for an overall time rate, which starts fast, then slows over time, and is consistent with supernova and gamma ray burst data. This allows galaxies more time to form, and in PST all matter's mass‐energy descends with the time rate (proportional time and energy changes in a gravitational field can be taken in the same way). This can also explain the “downsizing” sequence in galaxy formation, first described in 1996, in which stars in more massive galaxies formed earlier and quicker.

Tailoring masses to artificial molecules based on the shape of their wavefunctions

Abstract In this short paper, we examine artificial molecules composed of coupled artificial atoms such as quantum dots. Similar to artificial atoms, which have position-dependent effective masses for electrons, artificial molecules exhibit this characteristic while comprising more than one artificial atom. While in the literature, such artificial molecules are focused on the kinetic term of the electrons in such a setup, we consider the full description that includes the kinetic and potential terms that involve the nuclei. The proposed artificial molecules consist of nuclei and electrons coupled through Coulomb potentials and kinetic energy influenced by electronic position-dependent effective masses that also depend on the positions of the nuclei and the other electrons in the system. We demonstrate how the Schrödinger equation for such systems can be solved by assuming the entire shape of the molecular wavefunction, guided by a tailored non-parabolic energy-momentum relation for at least one electron within the molecular structure. Additionally, we show that instead of pre-specifying the entire form of the molecular wavefunction, we can consider the coupling between the electrons and nuclei to obtain the wavefunction of the system.

Shape transition and coexistence in Te isotopes studied with the quadrupole collective Hamiltonian based on a relativistic energy density functional

Shape transition and coexistence in Te isotopes studied with the quadrupole collective Hamiltonian based on a relativistic energy density functional

Comment on “Relativistic spinless energies and thermodynamic properties of sodium dimer molecule”

In this Comment we point out two incorrect results in a paper published recently in this journal. In the first place, the fact that the maximum number of vibrational energy levels is not a variable parameter of the model because it is determined by the potential-energy function and, in particular, by the dissociation energy. In the second place, we argue that the vibrational thermodynamic functions for an excited electronic state of a diatomic molecule are of no physical utility because any physical application requires the more relevant contribution of the lower electronic states to the canonical partition function. To illustrate this point we show the calculation of the equilibrium constant for the dimerization of sodium using only spectroscopic information about the ground electronic state. The theoretical expression agrees remarkably well with the available experimental data.

Dirac oscillator in a symmetric sextic anharmonic double-well potential

This paper investigates the relativistic Dirac analogue of a one-dimensional Schrödinger oscillator in a symmetric sextic anharmonic double-well potential, constructed via a non-minimal substitution technique. We show that the large component of the Dirac spinor obeys a Schrödinger-like equation, whose eigenvalues are used to determine the relativistic energy levels. These eigenvalues are computed using high-order Bender-Wu perturbation theory, resulting in an algebraic recursion relation for the expansion coefficients. A proper analytic formula describing the large-order behavior of these coefficients is derived, revealing their asymptotic factorial divergence. Additionally, a conjecture illustrating the dependence of these coefficients on the energy quantum numbers is proposed and confirmed. To overcome the challenge posed by the divergent nature of the perturbative eigenvalue expansion, Borel resummation with conformal mapping and Padé approximation are employed, leading to accurate results of the relativistic energy levels and their non-relativistic counterparts as functions of the coupling constants.

Critical Impact of Isospin Asymmetry in Elucidating Magicity Across Isotonic Chains of Different Mass Regions Using Relativistic Energy Density Functional

This study provides a comprehensive examination of the surface properties—particularly the symmetry energy and its contributing components—of isotonic chains across various mass ranges, including light, medium, heavy, and superheavy nuclei. We establish a correlation between nuclear symmetry energy and isospin asymmetry in different mass regions along isotonic chains with magic and semi-magic neutron numbers of N = 20, 40, 82, 126, and 172. Our approach integrates the coherent density fluctuation model within the relativistic mean-field (RMF) framework, utilizing both the non-linear NL3 and density-dependent DD-ME2 parameter sets. The methodology employs the Brueckner energy density functional in conjunction with our recently developed relativistic energy density functional (relativistic-EDF). The relativistic parameterization of the EDF at local density facilitates a consistent exploration of isospin-dependent surface properties across the nuclear landscape. In the present work, we successfully reproduce established shell closures and demonstrate that the relativistic approach yields significantly improved predictions for recognized magic numbers, particularly Z = 28 and 50. Additionally, we present compelling evidence for the presence of novel shell and sub-shell closures, specifically at Z = 34, 58, 92, and 118. These findings contribute to a nuanced understanding of nuclear surface properties while serving as a benchmark for future investigations and validations of nuclear models.

Improving relativistic energy density functionals with tensor couplings

Energy density functionals (EDFs) have been used extensively with great success to calculate properties of nuclei and to predict the equation of state of dense nuclear matter. Besides non-relativistic EDFs, mostly of the Skyrme or Gogny type, relativistic EDFs of different types are in widespread use. In these latter approaches, the effective in-medium interaction is described by an exchange of mesons between nucleons. In most cases, only minimal meson-nucleon couplings are considered. The effects of additional tensor couplings were rarely investigated. In this work, a new relativistic EDF with tensor couplings and density dependent minimal meson-nucleon couplings will be presented. The parameters of the model are determined using a carefully selected set of experimental data with realistic uncertainties that are determined self-consistently. Predictions for various nuclear observables, the nuclear matter equation of state, and properties of neutron stars are discussed.

Coherent Control of Relativistic Electron Dynamics in Plasma Nanophotonics

AbstractIntense femtosecond laser pulses interacting with solids can drive electrons to relativistic energies, enabling miniaturized particle accelerators and bright extreme‐UV light sources. In‐situ space‐time control of these electrons is crucial for developing next‐generation laser‐based accelerators but remains extremely challenging. A novel approach is presented to achieve such control by manipulating the local fields driving these electrons using a nanoengineered dielectric nanopillar target. Via experiments and simulations, it is demonstrated that this sub‐femtosecond and nanometer‐scale control enables enhanced electron acceleration and control of the directionality of relativistic electrons over a wide angular range and predicts the coherent formation of sub‐femtosecond electron bunches from the nanopillars. This research bridges nanophotonics and strong‐field plasma physics, offering new opportunities for in‐situ control of high‐energy particles and advancements in plasma technology.

Impact of Tolman–Kuchowicz solution on dark energy compact stars in [formula omitted] theory

In this study, we model a new relativistic dark energy star by enforcing a static and isotropic spherically symmetric fluid distribution within the framework of f(R) gravity, utilizing the Starobinsky model in the field equations. The analysis is conducted using the Tolman–Kuchowicz metric potentials and by employing the equation of state which models dark energy with its density proportional to the isotropic perfect fluid density. By applying junction conditions and considering the Schwarzschild solution as the exterior geometry, we compute the unknown parameters of the constructed model. The physical plausibility of the model is thoroughly examined, ensuring the regularity and consistency of metric functions and matter variables. We analyze energy conditions to confirm the system’s physical realism and derive the mass–radius relationship along with gravitational redshift, providing significant insights into the structure of the compact star candidate 4U 1820-30. The hydrostatic equilibrium is evaluated using the TOV equation, while stability is determined through the causality condition and adiabatic index. The results demonstrate that the proposed model, for the chosen values of the model parameter, is physically consistent and satisfies all necessary stability criteria, providing a viable and realistic description of a compact stellar structure influenced by dark energy.

Electromagnetic signatures of black hole clusters in the center of super-Eddington galaxies

Supermassive black holes (SMBHs) at the centers of active galaxies are fed by accretion disks that radiate from the infrared or optical to the X-ray bands. Several types of objects can orbit SMBHs, including massive stars, neutron stars, clouds from the broad- and narrow-line regions, and X-ray binaries. Isolated black holes with a stellar origin (BHs of ∼10 M⊙) should also be present in large numbers within the central parsec of the galaxies. These BHs are expected to form a cluster around the SMBH as a result of the enhanced star formation rate in the inner galactic region and the BH migration caused by gravitational dynamical friction. However, except for occasional microlensing effects on background stars or gravitational waves from binary BH mergers, the presence of a BH population is hard to verify. In this paper, we explore the possibility of detecting electromagnetic signatures of a central cluster of BHs when the accretion rate onto the central SMBH is greater than the Eddington rate. In these supercritical systems, the accretion disk launches powerful winds that interact with the objects orbiting the SMBH. Isolated BHs can capture matter from this dense wind, leading to the formation of small accretion disks around them. If jets are produced in these single microquasars, they could be sites of particle acceleration to relativistic energies. These particles in turn are expected to cool by various radiative processes. Therefore, the wind of the SMBH might illuminate the BHs through the production of both thermal and nonthermal radiation.

Relativistic beam loading, recoil-reduction, and residual-wake acceleration with a covariant retarded-potential integrator

An algorithm is demonstrated that performs first-principles tracking of relativistic charged-particles. A covariant approach is used which relies on retarded vector potentials for trajectory integration instead of performing electromagnetic field calculations. When accounting for retardation effects, the peak vector potential and corresponding Lorentz force in the direction of travel increase asymptotically for high-β particles. This produces a very strong field distribution at small angles from the particle’s direction of travel, which can result in considerable change in momentum when approaching a conducting or charged object. We study these dynamics using protons and electrons at relativistic energies passing through apertures in conducting surfaces, where substantial energy shifts are observed for particles passing within roughly 10μm of the aperture boundary.We also simulate breaking a test particle’s line of sight with a conductor or other charged body. After this instant, the test particle continues to accelerate due to residual fields, but no longer produces an opposing force on any charged or conducting object; thus any recoil on the enclosing structure is effectively reduced. In this test, a 1% energy gain is observed for an 85 MeV electron traversing its reflected wake after having conducting plate in its path screened by a dielectric object.We then incorporate a micro-scale dielectric laser acceleration (DLA) device into our simulations. Compared with a 2 mm DLA on its own, we find a factor of two increase in energy gain when adding a series of conducting-surface choppers.

Study of net-baryon higher moments in PNJL model and their expectation for net-proton using the subensemble acceptance method for the search of QCD critical point

The critical point is one of the most important aspects of the QCD phase diagram of strongly interacting matter. The nonmonotonic behavior of the higher-order moments of conserved quantities like net-baryon (ΔB), net-charge (ΔQ), and net-strangeness (ΔS) are believed to be the signatures of the QCD critical point as a function of energy. We study the effect of the QCD critical point on moments of net-baryon in the Polyakov loop enhanced Nambu-Jona-Lasinio (PNJL) model of QCD with six-quark and eight-quark interactions for finite and infinite volume systems. The study is performed at energies similar to Relativistic Heavy-Ion Collider beam energy scan. Experimentally measuring conserved quantities is difficult due to systematic limitations. Therefore, net-proton, net-pion, and net-kaon are measured as the proxy of ΔB, ΔQ, and ΔS. Recent studies in the subensemble acceptance method on the hadron resonance gas (HRG) model show the dependency of the measured higher-order moment on the experimental acceptance. We applied the subensemble acceptance method to analyze the behavior of κσ2 of net-baryon distribution within the subvolume system for various acceptance fractions. These results can be directly mapped to the subvolume (particle) percentage of the total volume (conserved quantities). Our findings are compared to the solenoidal tracker at RHIC (STAR) net-proton and proton data with different energies to investigate the presence of the critical point. Additionally, these results are also compared with the ultrarelativistic quantum molecular dynamics (UrQMD), HRG model, and available lattice data. Published by the American Physical Society 2024

Molecular Structure Theory without the Born-Oppenheimer Approximation: Rotationless Vibrational States of LiH.

Low-lying rotationless states of the lithium hydride molecule are studied in the framework of the variational method without assuming the Born-Oppenheimer (BO) approximation. Highly accurate solutions to the six-particle (two nuclei and four electrons) Schrödinger equation are obtained by means of expanding the wave functions of the considered states in terms of many thousands of all-particle explicitly correlated Gausssians. The basis functions are optimized independently for each state using the analytic energy gradient with respect to the nonlinear parameters. The non-BO wave functions obtained in the calculations are used to evaluate the leading-order relativistic and quantum electrodynamics energy corrections in the framework of the perturbation theory. The geometric structure of the molecule in the ground and excited states is discussed based on the analysis of the nucleus-nucleus correlation functions. The non-BO energies and structural parameters obtained of this work are compared with the most accurate BO results currently available.

Investigate of thermodynamic behavior of magnetized two-flavor quark-gluon plasma

In this paper, we extend the self-consistent quasi-particle model proposed by Zong et al. [Phys. Lett. B 711, 65 (2012)] to the case of finite magnetic field. The vacuum infinity zero-point energy is successfully eliminated by introducing a classical thermo-magnetic background field [Formula: see text] in the effective Lagrangian based on Zong’s method. By considering relativistic Landau energy levels, we have applied the improved quasi-particle model to the case of a two-flavor quark gluon plasma. We obtain a finite partition function and calculate the energy density, pressure and entropy density at zero chemical potential. These results are qualitatively consistent with the results of previous literature works.

Effects of gravity rainbow on scalar bosonic and oscillator fields in Bonnor–Melvin space-time with a cosmological constant

In this paper, we explore the relativistic quantum motion of spin-zero scalar charge-free particles influenced by rainbow gravity’s (RG’s) in Bonnor–Melvin magnetic space-time, a four-dimensional solution featuring a positive cosmological constant. We solve the Klein–Gordon equation in this scenario by using two sets of rainbow function: (i) f(χ)=1(1-βχ), h(χ)=1 and (ii) f(χ)=1(1-βχ)=h(χ), where 0<χ=|E|Ep≤1 with Ep being the Planck’s energy, E is the particle’s energy, and β is the rainbow parameter. Furthermore, we study the relativistic quantum oscillator through the Klein–Gordon oscillator equation in the same Bonnor–Melvin magnetic space-time under RG effects. Employing the first pair of rainbow function, we obtain an approximate eigenvalue solution of the quantum oscillator fields. Notably, we demonstrate that the relativistic energy profile of scalar and oscillator particles are influenced by the topology of the geometry and the cosmological constant which is related with the magnetic field strength lies along the symmetry axis. Additionally, we see the impact of rainbow parameter on these approximate relativistic energy profiles in both quantum systems.

High-Precision Experiments with Trapped Radioactive Ions Produced at Relativistic Energies

Research on radioactive ion beams produced with in-flight separation of relativistic beams has advanced significantly over the past decades, with contributions to nuclear physics, nuclear astrophysics, atomic physics, and other fields. Central to these advancements are improved production, separation, and identification methods.The FRS Ion Catcher at GSI/FAIRexemplifies these technological advancements. The system facilitates high-precision experiments by efficiently stopping and extracting exotic nuclei as ions and making these available at thermal energies. High-energy synchrotron beams enhance the system’s capabilities, enabling unique experimental techniques such as multi-step reactions, mean range bunching, and optimized stopping, as well as novel measurement methods for observables such as beta-delayed neutron emission probabilities. The FRS Ion Catcher has already contributed to various scientific fields, and the future with the Super-FRS at FAIR promises to extend research to even more exotic nuclei and new applications.