物理最新文献

We study the thermodinamic features of static, spherically-symmetric Schwarzschild black holes adopting different types of Barrow entropy. Specifically, in addition to the standard Barrow entropy, we consider a logarithmic-corrected type of this entropy by taking into account some loop quantum gravity effects. Moreover, we investigate the black hole thermodynamics from the viewpoint of Barrow entropy in presence of non-extensivity effects coming from the Tsallis statistics. Finally, we compare the results obtained for different Barrow-based entropies.

The characteristics of cylindrical dust-ion-acoustic solitary waves in an unmagnetized, collisionless dusty plasma system with oppositely charged ions, immobile dust particles and non-extensive electrons are investigated. Using the reductive perturbation method, a ((3+1))-dimensional cylindrical Kadomtsev–Petviashvili (cKP) equation is derived, and this is valid for small but finite amplitude dust-ion-acoustic waves. This model supports positive as well as negative potential solitary structures. Analyzing various plasma parameters on the solitary profile revealed that the polarity, amplitude and width of the waves vary significantly. Higher electron number density increases the formation region of solitary structures. The plasma system accommodates both supersonic and subsonic wave modes. The subsonic waves are governed by the thermal effect, and the supersonic waves are ion-acoustic in character. The time evolution of dust-ion-acoustic wave is shown and also the propagation characteristics with radial, azimuthal and axial coordinates have been performed. These findings contribute to enriching our knowledge of nonlinear events that may occur in astrophysical settings and laboratory plasmas, where positive and negative ions, non-extensive electrons and negatively charged static dust grains are available.

The prevalence of compost and its integration within the bio-circular economy, facilitating the seamless conversion of bio-waste into compost, present an auspicious avenue for the exploration of renewable energy storage solutions. Thus, the current study investigates the effect of electrolytes on faradic and non-faradic processes of charge storage in a symmetrical device design based on compost. The inquiry examines the composts as an electrode material and the influence of various current collectors (G–G, Cu–Cu and IN–IN) across distinct aqueous electrolyte environments (1 M KNO₃, 1 M KCl and 1 M KOH). The findings reveal the composts’ capacity to accommodate both capacitive and non-capacitive charge storage processes within a symmetric dual-current collector apparatus, showcasing the multifaceted charge storage modalities akin to those observed in capacitors and batteries. The electrochemical assessments, conducted through cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) profiling, and electrochemical impedance spectroscopy (EIS), elucidate the non-faradaic and faradaic charge storage mechanisms in terms of the charge storage efficiency, temporal characteristics of the charge and discharge cycle, specific capacitance, and specific capacity. The results obtained evince the superior charge storage capabilities of the compost samples across various electrolyte solutions relative to the aqueous media. The compost specimen featuring a C:N ratio of 145.44 in a 1 M KCl solution assembled in a symmetric G–G current collectors device exhibited the optimal electrochemical performance. At a scan rate of 100 mV/s within a potential window of ± 4.5 V, the CV studies exhibited an area under the curve of 3.3142C, a specific capacitance of 18.4mF/g and a specific capacity of 82.8 mC/g, while the GCD studies were characterised by a charging time of 51 s, a discharging time of 47.2 s, a specific capacitance of 10.4 mF/g and a specific capacity of 94.4 mC/g at an applied current of 400 mA within a potential window of ± 4.5 V.

We present a scheme to demonstrate the manipulation of spatially dependent four-wave mixing (FWM) in a five-level atomic system controlled by an external magnetic field. The propagation of the FWM field in a five-level atomic system is investigated using a dynamic model based on the Maxwell equation, and an analytical solution for FWM is derived via the Fourier transform. Our results show a significant phase twist symmetry of the FWM field resulting from the external magnetic field, and there is no spatial phase twists or absorption at the symmetric points. Notably, in response to an external magnetic field, the peak conversion efficiency of FMW occurs at symmetrical points where the FWM phase twist direction changes symmetrically with the magnetic field. In addition, it is found that increasing vortex pump intensity or adjusting the control field power may enhance FWM conversion efficiency. Our findings have potential applications in magnetic detection and contribute to an extensive awareness of nonlinear phenomena in the atomic system.

The discovery of non-zero neutrino masses and mixings that the Standard Model (SM) cannot accommodate opens up the possibility of the existence of Heavy Neutral Leptons (HNLs). In minimal models, the HNL production and decay are controlled by SM interactions and the mixing between HNLs and the active neutrino and typically result in relatively long lifetimes if the masses are in the MeV–GeV range. We have studied the physics case and technical feasibility for a dedicated HNL search using the NuMI beam at an ICARUS-like detector. Our analysis demonstrates that the constraints on the mixing of the HNL as a function of its mass for an ICARUS-like detector with NuMI beam are highly competitive with the limits obtained from present experiments.

We have recently developed a nuclear model, which is a natural extension of the pn-QRPA model, specially designed to describe double charge exchange (DCE) processes generated by two-body DCE transition operators. It is based on the Quasiparticle Tamm–Dancoff approximation (QTDA) for pn and 2p2n excitations in intermediate and final nuclei, respectively, and will be called DCEQTDA. As such, this model, having the same number of free parameters as the pn-QRPA, also brings into play the excitations of four quasiparticles to build up the final nuclear states, which are then used to evaluate the nuclear matrix elements (NMEs) for all (0^+) and (2^+) final states, including resonances, and not just for the ground state as in pn-QRPA. In addition, it allows us to evaluate: (a) the values of (Q_{{beta }{beta }}), (b) the excitation energies in final nuclei, and (c) the DCE sum rules, which are fulfilled in the DCEQTDA. So far, this model has been used mainly to calculate double beta decays with the emission of two neutrinos ((2nu beta beta )-decay). Here, we extend it to the study of these processes when no neutrinos are emitted ((0nu beta beta )-decay), evaluating them in a series of nuclei, but paying special to: (i) (^{76})Se, which have been measured recently in the GERDA and MAJORANA experiments, and (ii) (^{124})Te, for which the first direct observation of the double electron capture (2nu ) has been performed with the XENON1T dark matter detector. We obtain good agreement with the data for both the ground state and the excited states. The validity of the DCEQTDA model is checked by comparing the calculation with the experimental data for the (2nu {beta }{beta }) NMEs, and for the (Q_{{beta }{beta }}), in a series of nuclei.

We analyze general expressions for the quantum phases of dipoles and pointlike charges in an electromagnetic field, applying the strong relativistic limit and using the principle of superposition of quantum phases first proposed in Kholmetskii and Yarman (EPL 120: 40007, 2017). This way we derive a new expression for the AB phase of electrically charged particles, which is both gauge-invariant and Lorentz-invariant, and discuss its implications.

The objective of this research is to explore the influence of praseodymium incorporation into cobalt ferrite nanoparticles, derived from sol-gel, on their response to hydrogen gas. Additionally, we investigated the hydroxyl scavenging capacity of praseodymium ions by comparing the results obtained at low relative humidity (RH ~ 20%) and high relative humidity (RH ~ 50%). Our findings revealed that the optimal gas sensing properties of the CoFe_2 − xPr_xO₄ semiconductor (where x = 0, 0.02, 0.04, 0.06) were achieved with a Pr concentration of 0.02 at a working temperature of 300 °C. Scanning electron microscopy and mapping Energy-dispersive X-ray spectroscopy (EDS) analysis of Pr-doped CoFe₂O₄ nanoparticles provided evidence for the existence of a secondary phase at higher Pr concentrations, which impacted gas-sensing performance when x > 0.02. Furthermore, the addition of palladium proved to be effective in enhancing the moisture-resistant gas-sensing properties of the CoFe_1.98Pr_0.02O₄ gas sensor. The synergistic interaction between palladium and praseodymium ions was responsible for the observed enhanced anti-humidity and hydrogen gas detection characteristics.

(K_0.41Na_0.59)(Nb_0.84Sb_0.06Ta_0.10)O₃ + x wt% CuO (KNNST + x Cu, 0 ≤ x ≤ 0.1) ceramics were prepared using a two-step sintering technique. The effects of CuO on the sintering behavior, the phase structure, surface morphologies, and the piezoelectric properties of the (K_0.41Na_0.59)(Nb_0.84Sb_0.06Ta_0.10)O₃ (KNNST) ceramics were investigated in details. The experimental results showed that CuO doping improved the “hardened” KNNST + x Cu ceramics through reduced dielectric loss (tanδ) and greatly enhanced mechanical quality factor (Q_m). Additionally, CuO doping significantly improved the piezoelectric properties at low sintering temperatures. The KNNST ceramics obtained excellent overall electrical properties of d₃₃ = 265 pC/N, k_p = 0.50, k_p = 0.41, Q_m = 420, ε_r = 1173, tanδ = 0.015, P_r = 15 µC/cm², and T_m = 325 °C at a sintering temperature of 1050 °C and 0.075 wt% CuO content, which showed that KNNST ceramics were promising candidates for power applications. Besides, CuO content of 0.1 wt% had the highest recoverable energy storage density (W_rec) of 0.34 J/cm³ and energy storage efficiency (η) of 61.0%, expanding the scope of application for CuO-doped KNNST ceramics.

A well-motivated cosmological hybrid inflation scenario based on no-scale SUGRA is considered. It is demonstrated that an extra suppressed R-symmetry breaking term (S^n) with (nge 4) needs to be included in order to realize successful inflation. The resulting potential is found to be similar (but not identical) to the one in the Starobinsky inflation model. A relatively larger tensor-to-scalar ratio (rsim 10^{-2}) and a spectral index (n_sapprox 0.965) are obtained, which are approximately independent of n.