Strong Force Field Research Articles

Relativistic spin dynamics for vector mesons

We propose a relativistic theory for spin density matrices of vector mesons based on Kadanoff-Baym equations in the closed-time-path formalism. The theory puts the calculation of spin observables such as the spin density matrix element ρ00 for vector mesons on a solid ground. Within the theory we formulate ρ00 for ϕ mesons into a factorization form in separation of momentum and spacetime variables. We argue that the main contribution to ρ00 at lower energies should be from the ϕ fields that can polarize the strange quark and antiquark in the same way as electromagnetic fields. The key observation is that there is correlation inside the ϕ meson wave function between the ϕ field that polarizes the strange quark and that polarizes the strange antiquark. This is reflected by the fact that the contributions to ρ00 are all in squares of fields that are nonvanishing even if the fields may strongly fluctuate in spacetime. The fluctuation of strong force fields can be extracted from ρ00 of unflavored vector mesons as links to fundamental properties of quantum chromodynamics. Published by the American Physical Society 2024

Global spin alignment of vector mesons and strong force fields in heavy-ion collisions

Global spin alignment of vector mesons and strong force fields in heavy-ion collisions

Mechanical structure of a spin-1 particle

We investigate the mechanical structure of a spin-1 particle. Introducing three different frameworks, i.e., the three-dimensional (3D) Breit frame, the two-dimensional (2D) Breit frame, and the 2D infinite momentum frame (equivalently the two-dimensional Drell-Yan frame), we scrutinize the 2D and 3D energy-momentum tensor (EMT) distributions in these frames. We first derive the EMT distributions in the 2D Breit frame by performing the Abel transformation. The mass distribution in the 2D Breit frame contains an additional monopole contribution induced geometrically. The pressure distribution in the 2D Breit frame also gets an induced monopole structure. When the Lorentz boost is carried out, the mass distribution in the 2D infinite-momentum frame acquires the induced dipole term. Similarly, we also have the induced dipole contributions to the pressure and shear-force densities. We visualize the 2D mass distributions when the spin-1 particle is polarized along the $x$- and $z$-axes. We observe that the 2D mass distribution in the infinite momentum frame exhibit clearly the induced dipole structure when the spin-1 particle is polarized along the $x$-axis. We also discuss the strong force fields inside a polarized spin-1 particle.

Pattern of global spin alignment of ϕ and K*0 mesons in heavy-ion collisions.

Notwithstanding decades of progress since Yukawa first developed a description of the force between nucleons in terms of meson exchange1, a full understanding of the strong interaction remains a considerable challenge in modern science. One remaining difficulty arises from the non-perturbative nature of the strong force, which leads to the phenomenon of quark confinement at distances on the order of the size of the proton. Here we show that, in relativistic heavy-ion collisions, in which quarks and gluons are set free over an extended volume, two species of produced vector (spin-1) mesons, namely ϕ and K*0, emerge with a surprising pattern of global spin alignment. In particular, the global spin alignment for ϕ is unexpectedly large, whereas that for K*0 is consistent with zero. The observed spin-alignment pattern and magnitude for ϕ cannot be explained by conventional mechanisms, whereas a model with a connection to strong force fields2-6, that is, an effective proxy description within the standard model and quantum chromodynamics, accommodates the current data. This connection, if fully established, will open a potential new avenue for studying the behaviour of strong force fields.

Vector meson spin alignment by the strong force field

Vector meson spin alignment by the strong force field

Medium modification of the nucleon mechanical properties: Abel tomography case

We investigate how the gravitational form factors of the nucleon undergo changes in nuclear matter, emphasizing the Abel transformation from the three-dimensional (3D) Breit frame to the two-dimensional (2D) light-front frame. Since the gravitational form factors reveal the mechanical structure of the nucleon, we examine also the medium modifications of the energy–momentum, pressure, and shear-force distributions. We scrutinize the stabilities of the nucleon in nuclear matter. For this purpose, we employ the in-medium modified SU(2) Skyrme model to study these mechanical quantities of the nucleon, since it provides a simple but clear framework. In this in-medium modified SU(2) Skyrme model, the modification of pionic properties is performed by using low-energy pion-nucleus scattering data and the saturation properties of nuclear matter near the normal nuclear matter density, rho _0=0.5m_pi ^3. The results reveal how the nucleon swells in nuclear matter as the mass distribution of the nucleon is broadened in medium. We also show that the mean square radii corresponding to the mass and angular momentum distributions increase in nuclear medium. This feature is kept both in 3D and 2D cases. We visualize how the strong force fields inside the nucleon in the 2D plane are distributed and illustrate how these forces undergo change in nuclear matter.

Gravitational Force is a Type of Physical Interaction between Gluon Fields: Molecular Motions of Gases

This study presents a Gluon Gravity Model, to explain the mechanism of gravity. With the development of quantum chromodynamics since 1970, Newton's law of universal gravitation and Einstein's theory of general relativity need to be reinterpreted. Like an electric charge causes an electric field, the color charges in quantum chromodynamics were introduced into the gravitational field. The gluons mediating strong force can bring about a new color field around the strong force field owing to their color charges. This new color field of charges becomes a gravitational field in Gluon Gravity Model. This model is supported by the facts that most of the atomic mass is composed of the gluon field energy and the similarity between the two formulas of Coulomb's law and Newton's laws of universal gravitation. Additionally, it is possible to explain the gas molecular motions by applying the Gluon Gravity Model to the gluon fields within a proton.

Strong force fields and stabilities of the nucleon and singly heavy baryon Σc

We investigate the strong force fields and stabilities of the nucleon and the singly heavy baryon $\Sigma_c$ within the framework of the chiral quark-soliton model. Having constructed the pion mean fields in the presence of the $N_c-1$ level quarks self-consistently, we are able to examine the gravitational form factors of $\Sigma_c$. We mainly focus in the present work on the stability conditions for both the nucleon and $\Sigma_c$ and discuss the strong force fields and their physical implications. We also present the results for the gravitational form factors and relevant observables, emphasising the difference between the nucleon and $\Sigma_c$.

Ab initio study of intrinsic defects and diffusion behaviors in solid molecular hydrogens

The behaviors of intrinsic defects in solid molecular hydrogens (H2) were investigated using ab initio calculations based on density functional theory. The results show that the formation energy of a vacancy is dependent on molecule orientation in disordered hexagonal close-packed (hcp) H2 crystals, but independent of molecular orientation in face-centered cubic-Pa3 H2. Furthermore, H2 molecules generally prefer to occupy the basal octahedral sites in hcp and octahedral sites in Pa3 structures. The formation energies of an interstitial H2 depend sensitively on the volume of interstitial sites, and also on near spatial distributions of molecular axes of a H2 in hcp H2 crystals. The strong force field introduced by an interstitial H2 might induce the rotation of molecular axes and reduce the formation energy of the interstitial H2. The migration barrier energy of a vacancy in Pa3 is larger than the average in hcp structures. However, the H2 molecules prefer to jump though vacancies in the two structures of solid H2 than the interstitial migrations.

Classical-quantum correspondence in electron-positron pair creation

We examine the creation of electron-positron pairs in a very strong force field. Using numerical solutions to quantum field theory we calculate the spatial and momentum probability distributions for the created particles. A comparison with classical mechanical phase space calculations suggests that despite the fully relativistic and quantum mechanical nature of the matter creation process, most aspects can be reproduced accurately in terms of classical mechanics.

Kinetic Constraints in Diffusion

In the presence of strong external fields and steep gradients the flux formulae are not linear. The relation between the flux and the diffusion coefficient must be modified. The different flux-limited theories are presented. The flux formulae for solid systems far from equilibrium are derived and different forms of phenomenological flux limiters are discussed. It is shown that in order to accurately compute diffusion flow that is generated by strong force fields and/or discontinuities, the flux-limited diffusion must be considered. The flux limiters improve the spatial accuracy and allow to avoid baseless oscillations in the solutions.

Non-Maxwell velocity distributions in inhomogeneous materials

Determining velocity distribution functions for ensembles is one of the most fundamental problems in statistical mechanics. In this paper, based on the results of computer molecular dynamics (MD) methods, we point out that the velocity distribution of low-mass classical particles subjected to a strong force field in a heavy atom environment is generally noncanonical. When the system reaches equilibrium, a non-Maxwellian distribution persists. The effective temperature of some of the low-mass particles may be one or two orders of magnitude greater than the average temperature of the system. “Cold” fusion may thus be enhanced by as much as 30–50 orders of magnitude over that calculated on the basis of 300K Maxwell distributions.

Non-Maxwell velocity distributions in equilibrated fluids

In this paper, using supercomputer molecular dynamics methods, we further demonstrate that the velocity distribution of a low-mass classical particle subjected to a strong force field in a heat bath of heavy particles is non-Maxwellian. When the system reaches equilibrium, the non-Maxwellian distribution persists for velocity components along the field direction.

Molecular Ion Dissociation by Thin Films

One of the fundamental limitations in mass spectrometry arises in attempts to differentiate betwoeen atomic and nuclear ions having the same charge to mass ratio. Partial dissociation of complex ions in a mass spectrometer has been observed. By using a three-stage mass spectrometer, complete dissoclation of molecular ions has been achieved. The film acts as a strong force field at a discrete point in the beam trajectory causing uncorrelated forces to act on the constituent atoms of the molecules. Further experiments are in progress utilizing these films as well as thin nickel films. (A.C.)