The European Physical Journal C最新文献

In the present work, we propose to investigate the production of (d_{N Omega }) in the (Omega ^{-} d rightarrow p d_{N Omega }^-) process by utilizing an effective Lagrangian approach, where (d_{N Omega }) is identified as (NOmega ) bound state with the binding energy (E_{b}=2.46) MeV. Experimentally, the J-PARC hadron facility proposed to investigate the (K^{-}p rightarrow Omega ^{-} bar{K}^{(*)0} K^{+}) process, which is expected to yield an (Omega ) beam with the momentum of approximately 3 GeV. Additionally, theoretical studies of the (psi (2S) rightarrow Omega ^{-} bar{Omega }^{+}) process at BESIII provided an (Omega ) beam with the momentum of 774 MeV. Considering these two potential (Omega ) beam sources, our estimations show that for the (Omega ^{-} d rightarrow p d_{N Omega }^-) process, the cross sections are (Big (329.7^{+26.9}_{-49.6}Big )) (mu )b, (Big (174.0^{+26.5}_{-38.2}Big )) (mu )b, (Big (16.9^{+7.4}_{-7.7}Big )) (mu )b, and (Big (2.0^{+1.8}_{-1.4}Big )) (mu )b at (P_{Omega } =) 0.7, 0.9, 2.0, and 4.0 GeV, respectively, where the central values are estimated with (Lambda _{r}=1.0) GeV, and the errors come from the variation of (Lambda _{r}) from 0.8 to 1.2 GeV. We also estimate the differential cross sections, which reach the maximum at the forward angle limit. In addition, since the (d_{N Omega }) dibaryon predominantly decays into (Xi Lambda ). Therefore, we further investigate the (Omega ^{-} d rightarrow p Xi ^- Lambda ) process and estimate the relevant cross sections. It is expected that the present estimations can be tested by further experimental measurements at J-PARC and STCF in the future.

Based on the Comisso–Asenjo mechanism, we investigate the kinematic images of plasma before and after magnetic reconnection in Kerr–Anti-de Sitter(Kerr–AdS) black holes. Following a brief review of the Comisso–Asenjo process in Kerr–AdS black holes, we introduce the hotspot model and the imaging method. Building upon these foundational theories, we obtain the trajectory of the plasma and the temporal evolution of the hotspot images. It is found that there are three flares within the observing time, which is driven by the Comisso–Asenjo mechanism. We also discuss the influence of the cosmological parameter on the hotspot imaging. The results indicate that the hotspot image enlarges as the absolute value of (Lambda ) increases, demonstrating that the cosmological constant significantly affects the hotspot.

We investigate the interplay between quantum thermodynamics, quantum correlations, and quantum coherence within the framework of the Unruh–DeWitt (UdW) detector model. By analyzing both the steady and dynamical states of various quantum resources-including steerability, entanglement, quantum discord, and coherence-we study how these resources evolve under Markovian and non-Markovian environments. Furthermore, the hierarchical structure relating quantum correlations and quantum coherence is established. We also examine the thermodynamic performance of a quantum heat engine, highlighting the influence of memory effects and classical correlations on heat exchange, work extraction, and efficiency.

This research paper explores the structure of hypothetical compact stars, known as strange stars, within the framework of a novel modified theory of gravity called (f(R,Sigma ,T)) gravity. This theory extends General Relativity by making gravity dependent not only on the Ricci curvature scalar R but also on a torsion scalar (Sigma ) and the trace of the matter energy–momentum tensor T. This introduces a richer coupling between geometry and matter. The study presents a highly exotic, multi-layered stellar model composed of five distinct regions, each with a unique equation of state and geometric properties. The model features a dark-energy-like core with powerful repulsive gravity (anti-gravity), surrounded by successive layers of dust, exotic radiation, and a stiff matter crust, all enveloped by a standard Schwarzschild vacuum exterior. A key finding is the prevalence of negative energy densities and pressures in several layers, a hallmark of exotic matter. These configurations, enabled by the (f(R,Sigma ,T)) framework, lead to repulsive gravitational effects that radically alter the star’s internal equilibrium. The analysis demonstrates how additional geometry-driven forces within this theory can support such exotic structures, potentially preventing gravitational collapse and resulting in a stable, non-singular object. This work demonstrates that (f(R,Sigma ,T)) gravity allows for new and complex classes of compact objects with stratified, exotic matter distributions, whose properties and observational signatures would differ significantly from those predicted by standard General Relativity.

We propose a covariant extension of general relativity in which the local effective dimension of spacetime is promoted to a dynamical, curvature-induced field on an underlying four-dimensional manifold. Deviations from four dimensions are encoded in a scalar degree of freedom (varepsilon (x)), defining (D_{textrm{eff}}(x)=4-varepsilon (x)), which enters the gravitational action through a dimension weight (v(varepsilon )) multiplying the Einstein–Hilbert term and a scalar potential (U(varepsilon )). At the level of the field equations, these ingredients combine into a curvature-sensitive effective potential (V(varepsilon ,R)) for the dynamical dimension field, where R is the Ricci scalar. In the limit (varepsilon rightarrow 0) and (v(varepsilon )rightarrow 1), the weak-field regime of general relativity is continuously recovered. We derive the modified Einstein equations and the equation of motion for (varepsilon ), showing that the resulting framework is scalar–tensor-like in structure, with the additional field controlling the local effective dimensionality of spacetime rather than describing an independent matter component. As benchmark applications, we study static, spherically symmetric configurations and a spatially flat Friedmann–Lemaître–Robertson–Walker background, where curvature-induced dimensional effects lead to controlled deformations of the mass–radius relation in compact objects and small corrections to the background expansion history.

Ultralight dark matter (ULDM) has emerged as a compelling alternative to the standard cold dark matter (CDM) model by forming quantum-pressure-supported solitonic cores that address small-scale structure anomalies. In this work, we investigate the dynamics of solitons in ULDM by numerically evolving scalar field configurations under gravity, incorporating a range of interaction terms. We analyse soliton formation, stability, and collisions driven solely by quantum pressure and gravity, focusing first on the non-interacting case. We then introduce self-interactions via quartic, axion monodromy, logarithmic, and Sinh-Gordon potentials, each inducing distinct dynamical behaviour: repulsive quartic terms enhance stability, attractive interactions can lead to collapse, axion monodromy introduces saturation effects that modify core compactness, logarithmic terms suppress central density growth, and Sinh-Gordon interactions lead to deformation and fragmentation at high strengths. In order to analyse the effect of photon interactions beyond self-interactions, we observe the destabilization of solitonic structures even in the absence of scalar self-couplings. When both self- and photon-interactions are incorporated, soliton dynamics become highly sensitive to the specific potential, significantly influencing post-collision behaviour and long-term coherence. We provide a comprehensive analysis of soliton dynamics in ULDM across varying interaction types and parameter regimes, highlighting the complex dynamical behaviour of these quantum structures.

In this study, we analyze f(R) gravity employing the ( f(R) = R+ alpha _1 R^p - alpha _2 R^{-q} ) model within the Friedmann–Lemaître–Robertson–Walker (FLRW) background. We derive the Friedmann equations via modified gravity action and subsequently reexpress them in terms of the standard Friedmann equations. Our investigation explores the behavior of a bouncing cosmological model within this modified gravity context, offering a potential solution to the singularity problem encountered in the standard Big Bang cosmology. We represent cosmological parameters as functions of cosmic time and scrutinize the conditions for a cosmic bounce. Additionally, we reconstruct the f(R) gravity model using the redshift parameter and graphically present cosmological parameters as functions of redshift. These plots reveal an accelerated nature of Universe expansion. Furthermore, we reconstruct f(R) gravity models for scale factors, (a(t) = e^{e^{lambda t}}) which exhibits the bouncing behavior. Finally, we investigated the stability scenario by examining the sound speed. The resulting graph of sound speed plotted against redshift confirms late-time stability.

Thermal interactions are ubiquitous in the cosmos, driving systems toward equilibrium. In this work, we investigate the evolution of thermal states across the early universe, encompassing the inflationary, radiation-dominated (RD), and matter-dominated (MD) eras, through the lens of Krylov complexity. Utilizing a purification scheme, we map the thermal state to a two-mode pure state, facilitating an open-system analysis of Krylov complexity in contrast to closed-system methodologies. Our numerical results demonstrate that Krylov complexity grows exponentially during inflation, indicating chaotic behavior, before saturating at nearly constant values in the RD and MD eras due to particle production via preheating. Furthermore, we analyze the Krylov entropy, which exhibits an evolutionary trend analogous to that of complexity. Crucially, our analysis reveals a dynamical transition in the universe’s dissipative nature: with the universe acting as a strongly dissipative system during inflation and transitioning to a weakly dissipative regime in the subsequent eras. These findings provide a novel quantum information perspective on early universe dynamics.

We study the production of (pseudo-) scalar particles, in general coined as axion-like particles (ALPs) in association with electrons and neutrinos in the muon decay process. For this purpose, we compute the decay width of the muon to a four-body channel using a (d=7) effective operator that couples the ALP to the Standard Model fermions, namely leptons and neutrinos. Assuming a dominant coupling of the ALP to the dark sector, we only consider ALP decays to invisible final states. To obtain constraints on our model using the existing measurements, we leverage data from the TRIUMF Weak Interaction Symmetry Test (TWIST) experiment and obtain bounds on the ALP-lepton coupling for masses in the range of (0< m_{phi } < m_{mu }/4), as allowed by kinematics. Using the precision of current TWIST measurements, we obtain an order of magnitude estimation necessary for future searches to further constrain the parameter space for such a setup. Furthermore, we find that keeping realistic considerations, the new physics contribution can possibly be enhanced even with a minimalistic modification to the fiducial area used in the experiment potentially allowing for stronger constraints. At the end, in an attempt to relax the assumption that ALP decays to invisible only, we also investigate its stability and find potential longevity within collider environments for the mass range considered in this study.

The Three-Higgs-Doublet Model (3HDM) extends the Standard Model by introducing two additional scalar doublets, leading to a rich spectrum of new particles: three neutral CP-even Higgs bosons ((h_1,) (H_2,) (H_3),) two neutral CP-odd Higgs bosons ((A_2,) (A_3),) and two charged Higgs bosons ((H_2^+,) (H_3^+).) In this work, we present a phenomenological study of the 3HDM at the future International Linear Collider (ILC) with a center-of-mass energy of (sqrt{s} = 1000,text {GeV}.) Applying a comprehensive set of theoretical and experimental constraints, we identify promising new physics signals with sufficiently large production cross-sections. Our analysis shows that (e^+e^- rightarrow H_2 A_2,) (e^+e^- rightarrow H_2 H_2 Z,) (A_2 A_2 Z,) (H_2 H_2^{pm } W^{mp },) (A_2 H_2^{pm } W^{mp }) and (H_1 H_2 A_2) are among the most sensitive channels to probe this extended Higgs sector. We demonstrate that a future ILC would offer a powerful platform to test these interactions and discover these heavier Higgs bosons thus providing evidence of physics beyond the Standard Model.