Coupling Constant Of Interaction Research Articles

Study of [formula omitted]/EC-decay properties of [formula omitted] shell nuclei using nuclear shell model

Our study employs the nuclear shell model to systematically compute the half-lives of β-decay for nuclei in the mass range of A=18−39, encompassing the majority of sd shell nuclei. This analysis utilizes the USDB and SDNN Hamiltonians. The theoretical outcomes contain calculations of various parameters such as Q-values, half-lives, excitation energy, logft values, and branching ratios. We explore these results with axial–vector coupling constant for weak interactions, denoted as gA(=1.27), and κ value (=6289). We perform calculations of Gamow Teller matrix elements for 116 decay processes to calculate the quenching factor; we found a quenching factor of q=0.794±0.05 for the USDB interaction and q=0.815±0.04 for the SDNN interaction. We have also calculated superallowed transitions 0+→0+ for seven nuclei. Further, we have also included the electron capture phase space factor for the required nuclei to calculate the half-lives. This inclusion leads to small contribution in results, particularly for nuclei where electron capture (EC) plays a significant role. The overall results are in agreement with the experimental data.

Monte Carlo studies of skyrmion stabilization under geometric confinement and uniaxial strain

Geometric confinement (GC) of skyrmions in nanodomains plays a crucial role in skyrmion stabilization. This confinement effect decreases the magnetic field necessary for skyrmion formation and is closely related to the applied mechanical stresses. However, the mechanism of GC is unclear and remains controversial. Here, we numerically study the effect of GC on skyrmion stabilization and find that zero Dzyaloshinskii–Moriya interaction (DMI) coupling constants imposed on the boundary surfaces of small thin plates cause confinement effects, stabilizing skyrmions in the low-field region. Moreover, the confined skyrmions are further stabilized by tensile strains parallel to the plate, and the skyrmion phase extends to the low-temperature region. This stabilization occurs due to the bulk anisotropic DMI coupling constant caused by lattice deformations. Our simulation data are qualitatively consistent with reported experimental data on skyrmion stabilization induced by tensile strains applied to a thin plate of the chiral magnet Cu2OSeO3.

Dimensional crossover of a Rabi-coupled two-component Bose–Einstein condensate in an optical lattice

Dimensionality is a central concept in developing the theory of low-dimensional physics. However, previous research on dimensional crossover in the context of a Bose–Einstein condensate (BEC) has focused on the single-component BEC. To our best knowledge, further consideration of the two-component internal degrees of freedom on the effects of dimensional crossover is still lacking. In this work, we are motivated to investigate the dimensional crossover in a three-dimensional (3D) Rabi-coupled two-component BEC. The spin degrees of freedom consist of the Rabi-like and inter- and intra- interaction coupling constants. The dimensional crossovers from 3D to 2D or 1D are controlled by the continuous increase of 1D or 2D lattice depth respectively. Then we analyze how the dimensionality of the model system combined with spin degrees of freedom can affect quantum fluctuations. Accordingly, the analytical expressions of the ground-state energy and quantum depletion of the system are obtained. Our results show that the dimensional crossover induces a characteristic 3D to quasi-2D or 1D crossover in the behavior of quantum fluctuations, with an emphasis on the separated effects of Rabi-like and inter- and intra- interaction coupling constants on the quantum fluctuations. Conditions for possible experimental realization of our scenario are also discussed.

Study of nonstrange quark stars within a modified NJL model

In this work, a modified Nambu-Jona-Lasinio (NJL) model with proper-time regularization is employed to study the properties of hypothetical nonstrange quark stars. The coupling constant of the four-fermion interaction in the conventional NJL model is modified as $G={G}_{1}+{G}_{2}⟨\overline{\ensuremath{\psi}}\ensuremath{\psi}⟩$ to highlight the feedback of the quark propagator to the gluon propagator. To study the dependence of the equation of state (EOS) on this modification as well as the vacuum pressure, we choose nine representative EOSs for comparison. It is found that a smaller ${G}_{1}$ leads to a stiffer EOS, and a higher vacuum pressure (i.e., a smaller bag constant) yields a softer EOS at low energy density. It is further shown that the heaviest quark star under this modified NJL model satisfies not only the recent mass measurement of PSR $\mathrm{J}0740+6620$, but also the radius constraints from x-ray timing observations. The corresponding tidal deformability is also in agreement with the observations of GW170817.

Observational imprints of our lost twin anti-universe

We consider observational consequences of the entanglement between our universe and a hypothetical twin anti-universe in the third quantization scheme of the canonical quantum gravity in order to make such a scenario falsifiable. Based on our recent and unique investigations we select some special form of the interuniversal interaction which allows the entanglement entropy of the pair of universes to diverge at the critical points of their classical evolution where the specific behaviour of the Hubble parameter plays the key role. We find that the modification of the cosmic microwave background (CMB) power spectrum due to the entanglement with our twin anti-universe for such models is enlarged for small modes k and small multipole numbers l. Our specific form of the interaction is then constrained by the Planck satellite data giving the interaction coupling constant bound to be lambda _olesssim {mathcal {O}}(10^{-56}),text {s}^{-3} which is small, but not negligible compared to the inflationary contribution. Some other coupling functions which allow more critical points are also briefly commented on in the context of their observational effect on CMB and other prospective observational data.

Chiral vortical catalysis

Gluon interaction introduces remarkable corrections to the magnetic polarization effects on the chiral fermions, which is known as the inverse magnetic catalysis. It is a natural speculation that the vorticity, which has many similar properties as magnetic field, would bring non-negligible contribution to the chiral rotational suppression. Using an intuitive semi-classical background field method we studied the rotation dependence of the effective strong interaction coupling constant. Contrary to the magnetic field case the rotation increases the effective coupling which would slow down the condensate melting with temperature. This could be named as the chiral vortical catalysis or inverse rotation suppression. Imposing such dependence on the 4-fermion coupling in the NJL model, we numerically checked this analysis qualitatively. The pseudo critical temperature is shown to rise with the rotation and approach saturation eventually which may be induced by the model cutoff.

Impurity-Induced Magnetization of Graphene.

We present a model of impurity-induced magnetization of graphene assuming that the main source of graphene magnetization is related to impurity states with a localized spin. The analysis of solutions of the Schrödinger equation for electrons near the Dirac point has been performed using the model of massless fermions. For a single impurity, the solution of Schrödinger’s equation is a linear combination of Bessel functions. We found resonance energy levels of the non-magnetic impurity. The magnetic moment of impurity with a localized spin was accounted for the calculation of graphene magnetization using the Green’s function formalism. The spatial distribution of induced magnetization for a single impurity is obtained. The energy of resonance states was also calculated as a function of interaction. This energy is depending on the impurity potential and the coupling constant of interaction.

Swampland conditions for higher derivative couplings from CFT

There are effective field theories that cannot be embedded in any UV complete theory. We consider scalar effective field theories, with and without dynamical gravity, in D-dimensional anti-de Sitter (AdS) spacetime with large radius and derive precise bounds (analytically) on the coupling constants of higher derivative interactions ϕ2□kϕ2 by only requiring that the dual CFT obeys the standard conformal bootstrap axioms. In particular, we show that all such coupling constants, for even k ≥ 2, must satisfy positivity, monotonicity, and log-convexity conditions in the absence of dynamical gravity. Inclusion of gravity only affects constraints involving the ϕ2□2ϕ2 interaction which now can have a negative coupling constant. Our CFT setup is a Lorentzian four-point correlator in the Regge limit. We also utilize this setup to derive constraints on effective field theories of multiple scalars. We argue that similar analysis should impose nontrivial constraints on the graviton four-point scattering amplitude in AdS.

Mapping 13C hyperfine couplings and exchange interactions in short-lived charge separated states of rigid donor-bridge-acceptor dyads.

A detailed experimental study on reversible photo-induced intramolecular charge separation is presented based on nuclear magnetic resonance detection of chemically induced dynamic nuclear polarization. From variation of such polarization with the external magnetic field, the coupling constants of isotropic and anisotropic hyperfine interactions at individual 13C sites are measured in the short-lived charge separated state of dyad molecules composed of donor-bridge-acceptor parts. The objects of study were rigid donor-bridge-acceptor dyads, consisting of triarylamine as a donor, naphthalene diimide as an acceptor, and a meta-conjugated diethynylbenzene fragment as a bridge. By systematic variation of side groups in the bridging moiety, their influence on the electron withdrawing strength is traced. In combination with similar data for the 1H positions obtained previously for the same compounds [I. Zhukov et al., J. Chem. Phys. 152, 014203 (2020)], our results provide a reliable basis for the determination of the spin density distribution in the charge separated state of such dyads.

Structure of the correlation coefficients S(Ee) and U(Ee) of the neutron β decay

In the standard effective V - A theory of low-energy weak interactions (i.e. in the Standard Model (SM)) we analyze the structure of the correlation coefficients S(E_e) and U(E_e), where E_e is the electron energy. These correlation coefficients were introduced to the electron-energy and angular distribution of the neutron beta decay by Ebel and Feldman ( Nucl. Phys. 4, 213 (1957)) in addition to the set of correlation coefficients proposed by Jackson et al. (Phys. Rev. 106, 517 (1957)). The correlation coefficients $S(E_e)$ and $U(E_e)$ are induced by simultaneous correlations of the neutron and electron spins and electron and antineutrino 3-momenta. These correlation structures do no violate discrete P, C and T symmetries. We analyze the contributions of the radiative corrections of order O(alpha/pi), taken to leading order in the large nucleon mass m_N expansion, and corrections of order O(E_e/m_N), caused by weak magnetism and proton recoil. In addition to the obtained SM corrections we calculate the contributions of interactions beyond the SM (BSM contributions) in terms of the phenomenological coupling constants of BSM interactions by Jackson et al. (Phys. Rev. 106, 517 (1957)) and the second class currents by Weinberg (Phys. Rev. 112, 1375 (1958)).

Disorder-induced phase transitions in a spinful one-dimensional system

We analyse a modified set of renormalisation group equations for disordered spinful fermions described by the Luttinger liquid model. The modification is necessary to take special care of the factitious admixture of the disorder to the interaction coupling constants undergoing renormalisation. Only properly separated amplitudes of elastic and inelastic processes allow the identification of true phases and the construction of the phase diagram (a similar procedure has been earlier implemented for the spinless case). In the spinful case, these modified equations enable us to demonstrate that in some region of the bare parameters values the phase diagram contains two massive phases, charge (CDW) and spin (SDW) density waves, which are separated by an insulating phase. These gapped phases are achieved at finite critical temperatures that vanish at the phase boundaries indicating the presence of a disorder-induced quantum phase transition. The critical temperatures as a function of disorder are reasonably well fit by a stretch exponential with the universal stretching critical exponent ν=1/3. A quantum phase transition between CDW and SDW phases driven by disorder strength has not been predicted before and this observation must be taken into account when analysing recent multiple experiments on phase transitions in quasi-one-dimensional structures.

Measurement of the proton spin structure at long distances

Measuring the spin structure of protons and neutrons tests our understanding of how they arise from quarks and gluons, the fundamental building blocks of nuclear matter. At long distances the coupling constant of the strong interaction becomes large, requiring non-perturbative methods to calculate quantum chromodynamics processes, such as lattice gauge theory or effective field theories. Here we report proton spin structure measurements from scattering a polarized electron beam off polarized protons. The spin-dependent cross-sections were measured at large distances, corresponding to the region of low momentum transfer squared between 0.012 and 1.0 GeV$^2$. This kinematic range provides unique tests of chiral effective field theory predictions. Our results show that a complete description of the nucleon spin remains elusive, and call for further theoretical works, e.g. in lattice quantum chromodynamics. Finally, our data extrapolated to the photon point agree with the Gerasimov-Drell-Hearn sum rule, a fundamental prediction of quantum field theory that relates the anomalous magnetic moment of the proton to its integrated spin-dependent cross-sections.

1/N expansion for stochastic fields in de Sitter spacetime

We propose a $1/N$ expansion of Starobinsky and Yokoyama's effective stochastic approach for light quantum fields on superhorizon scales in de Sitter spacetime. We explicitly compute the spectrum and the eigenfunctions of the Fokker-Planck operator for a O($N$)-symmetric theory with quartic selfinteraction at leading and next-to-leading orders in this expansion. We obtain simple analytical expressions valid in various nonperturbative regimes in terms of the interaction coupling constant.

Negative Matter as Unified Dark Matter and Dark ‎Energy: Simplest Model, Theory and Nine Tests

Based on Dirac’s negative energy, we propose and study the negative matter. Bondi’s results are wrong. First, the negative matter can be the simplest model of unified dark matter and dark energy. Next, we discuss various possible theories of the negative matter: some field equations, similar electrodynamics, field equations with non-symmetry, etc. Third, the quantum theory of negative matter is researched. Matter surrounded by dark-negative matter corresponds to an infinitely deep potential trap in quantum mechanics and forms a base of the universal wave-particle duality and quantum mechanics. Fourth, we propose the mechanism of inflation as the origin of positive-negative matters created from nothing. Fifth, assume that dark matter is completely the negative matter, and we may calculate an evolutional ratio between total matter and usual matter from 1 of inflation and the radiation-dominated universe to 7.88 of the present matter-dominated universe. It agrees with the observed value 6.36~7. Sixth, we research the relativity of the negative matter and theory in Lobachevskian geometry. Seventh, we propose a judgment test of the negative matter as dark matter is opposite repulsive lensing and other eight possible tests. Eighty, we propose a figure on the unification of the four basic interactions in three-dimensional space, in which the “running” coupling constants of strong and weak interactions transform each other. The negative matter as a candidate of unification of dark matter and dark energy is not only the simplest, and may explain inflation and be calculated and tested.

Structure Analysis and Characterization of Aminorex Analogue 4'-F-4-MAR

Objective To study the identification method for 4'-F-4-methylaminorex （4'-F-4-MAR） in samples without reference substance. Methods Gas chromatography-mass spectrometry （GC-MS）, ultra-high-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry （UPLC-QTOF-MS）, nuclear magnetic resonance （NMR） and Fourier transform infrared （FTIR） were comprehensively used for the structure identification of 4'-F-4-MAR in samples. Results Under the positive electrospray ionization （ESI+） mode, quasi-molecular ion in the first order mass spectrometry of the unknown compound was 195.092 6 and its molecular formula was inferred to be C10H11FN2O. The fragment ions in the mass spectrometry of the unknown compound were compared with the related fragment ions of 4,4'-dimethylaminorex （4,4'-DMAR） in literature. It was found that the main fragment ions of the unknown compound were all 4 bigger than the corresponding fragment ions of 4,4'-DMAR. Therefore, the unknown compound was inferred to be a 4,4'-DMAR analogue with a methyl substituted by a fluorine in the benzene ring. The equivalent protons at δ=7.30 and δ=7.06 in 1H-nuclear magnetic resonance （1H-NMR） spectra and the characteristic spin-spin coupling constants （1JC-F=245.2 Hz, 2JC-F=21.3 Hz, 3JC-F=8.1 Hz） for 13C-19F interactions in carbon spectra, further proved that the fluorine substituted methyl at the para-position of the benzene ring. Finally, the unknown compound was determined as 4'-F-4-MAR. Conclusion A method that comprehensively used the identification materials 4'-F-4-MAR in GC-MS, UPLC-QTOF-MS, NMR and FTIR is established and the fragmentation mechanism of fragmentation ions of 4'-F-4-MAR created under the two modes -- electron impact （EI） and electrospray ionization under collision induced dissociation （ESI-CID） is deduced. The information will assist forensic science laboratories in identifying this compound or other substances with similar structure in their case work.

Non-Newtonian Gravity in Strange Quark Stars and Constraints from the Observations of PSR J0740+6620 and GW170817

Abstract We investigate the effects of non-Newtonian gravity on the properties of strange quark stars (QSs) and constrain the parameters of the standard MIT bag model used to describe strange quark matter (SQM) by employing the mass of PSR J0740+6620 and the tidal deformability of GW170817. We find that, for the standard MIT bag model, these mass and tidal deformability observations would rule out the existence of QSs if non-Newtonian gravity effects are ignored. For a strange quark mass of m s = 95 MeV, we find that QSs can exist for values of the non-Newtonian gravity parameter g 2/μ 2 in the range of 1.37 GeV−2 ≤ g 2/μ 2 ≤ 7.28 GeV−2 and limits on the bag constant and the strong interaction coupling constant of the SQM model given by 141.3 MeV ≤ B 1/4 ≤ 150.9 MeV and α S ≤ 0.56. For a strange quark mass of m s = 150 MeV, QSs can exist for 1.88 GeV−2 ≤ g 2/μ 2 ≤ 6.27 GeV−2 and limits on the parameters of the SQM model given by 139.7 MeV ≤ B 1/4 ≤ 147.3 MeV and α S ≤ 0.49.

Pressure Dependence of Magnetic Properties in La(Fe,Si)13 : Multistimulus Responsiveness of Caloric Effects by Modeling and Experiment

For a better understanding of multistimuli-responsive caloric materials with a first-order transition and for optimization of their functional properties, it is necessary to predict the behavior of the material under changes of both magnetic field and pressure. Here, we design and build a special device that can provide a self-consistent set of parameters needed for the comprehensive characterization of multistimuli-responsive functional magnetic materials. Using this scientific instrument, a data set of simultaneously measured magnetization, ${M(T)}_{H}$, and volume magnetostriction, $\ensuremath{\omega}(T{)}_{H}$, values are obtained for ${\mathrm{LaFe}}_{11.4}{\mathrm{Si}}_{1.6}$ with a first-order transition. Furthermore, based on simultaneously measured M(T) and \ensuremath{\omega}(T) dependencies obtained at ambient pressure, we develop an approach that allows the behavior of magnetization under different pressures, ${M(T)}_{P}$, to be described analytically. Additional parameters, such as compressibility, \ensuremath{\kappa}(T); thermal expansion coefficient, \ensuremath{\alpha}(T); and magnetoelastic interaction or effective magnetovolume coupling constant, ${C}_{MV}$, are determined. For verification of our developed model, direct measurements of magnetization under external pressure (up to P = 1 GPa) are carried out on the same sample as that used for simultaneous measurement of magnetization and magnetovolume effect. A comparison of simulated ${M(T)}_{P}$ dependencies with experimental $M(T{)}_{P}$ confirms that our approach provides a more realistic behavior of transition temperature under pressure, ${T}_{C}(P)$, than that of the ${T}_{C}(P)$ predicted by the Bean-Rodbell model; thus, this approach is more suitable for predicting the behavior of multistimuli-responsive caloric materials with first-order transitions under changes of both magnetic field and pressure.

Solving the Bethe-Salpeter equation in Minkowski space for a fermion-scalar system

The ladder Bethe-Salpeter equation of a bound $(1/2{)}^{+}$ system, composed by a fermion and a scalar boson, is solved in Minkowski space, for the first time. The formal tools are the same already successfully adopted for two-scalar and two-fermion systems, namely the Nakanishi integral representation of the Bethe-Salpeter amplitude and the light-front projection of the fulfilled equation. Numerical results are presented and discussed for two interaction kernels: (i) a massive scalar exchange and (ii) a massive vector exchange, illustrating both the correlation between binding energies and the interaction coupling constants, as well as the valence content of the interacting state, through the valence probabilities and the light-front momentum distributions. In the case of the scalar exchange, an interesting side effect, to be ascribed to the repulsion generated by the small components of the Dirac spinor, is pointed out, while for the vector exchange the manifestation of the helicity conservation opens new interesting questions to be addressed within a fully nonperturbative framework, as well as the onset of a scale-invariant regime.

О свойствах бегущей константы связи сильного взаимодействия в области низких энергий

О свойствах бегущей константы связи сильного взаимодействия в области низких энергий

Interacting holographic Ricci dark energy as running vacuum

Earlier studies have shown that in a two component model of the universe with dark matter and the running vacuum energy, which is phenomenologically a combination of [Formula: see text] and [Formula: see text] either eternal deceleration or acceleration is produced in the absence of a bare constant in the density of the running vacuum. In this paper, we have shown that in the interaction scenario, where the interaction between matter and vacuum is introduced through a phenomenological term, the two component model is capable of causing a transition from a prior decelerated to a later accelerated epoch without a bare constant in the running vacuum density. On contrasting the model with the cosmological data, we have found that the interaction coupling constant is small enough for a slow decay of the running vacuum. The model is subjected to dynamical system analysis, which revealed that the end de Sitter phase of the model is a stable one. We did an analysis on the thermal behavior of the system, which shows that the entropy is bounded at the end stage so that the system behaves like an ordinary macroscopic system. Apart from these, we have also performed the state finder diagnostic analysis which implies the quintessence nature of running vacuum and confirms that the model will approach the standard [Formula: see text]CDM in the future.