The European Physical Journal C最新文献

In this work, we study the gravitational waveforms from the periodic orbits of a massive particle around a dyonic ModMax black hole. We begin with a brief analysis of the spacetime and then examine how its parameters influence the dynamics of a massive neutral particle using the Lagrangian formalism. In particular, we compute the characteristics of marginally bound orbits and innermost stable circular orbits. Our results show that the values of these quantities increase with the black hole charge Q and the screening parameter (gamma ). We then plot various periodic orbits, characterized by the integers (z,w,v). Finally, we present the gravitational waveforms associated with extreme mass ratio inspirals, consisting of a stellar-mass compact object orbiting a supermassive black hole.

In this work, we theoretically investigate strong gravitational lensing effects and evaluate various lensing observables of a static, spherically symmetric solution in the context of effective quantum gravity (EQG). Among the three types of solutions proposed in EQG backgrounds, this is the third type without having Cauchy horizons. This solution gives rise to black hole as well as horizonless wormhole solutions depending on the range of values of the parameters of the theory. Based on the data from SgrA* and M87* observations, possible bounds on the parameter are obtained. It is found that the horizonless wormhole solution is ruled out by SgrA* observations, but is allowed by M87* observations. We analyze and provide estimates of the lensing observables, some of which can potentially be detected by observational tools.

We demonstrate that QCD-like gauge dynamics can be consistently embedded within the Dark Technicolor paradigm by invoking the extended Most Attractive Channel hypothesis, thereby revitalizing conventional technicolor scenarios. In this framework, the Higgs mass is generated dynamically while remaining consistent with electroweak precision tests, including constraints from the S parameter. The flavor problem is resolved by incorporating the Standard Hierarchical VEVs Model, whereas a simple Froggatt–Nielsen construction is shown to be incompatible. Couplings of techni-hadrons such as (rho _textrm{TC}) and (eta _textrm{TC}^prime ) to Standard Model fermions are highly suppressed, leading to negligible direct fermionic signatures. Nevertheless, DTC mesons remain testable at the HL-LHC, HE-LHC, and future 100 TeV collider, with promising discovery channels including (bar{b}b), (tau ^+tau ^-), (tbar{t}), and (gamma gamma ).

The Belle Collaboration recently reported a potential candidate for the spin-2 (D^*bar{D}^*) partner of the X(3872), denoted as (X_2), with a mass of ((4014.3pm 4.0pm 1.5)) MeV and a width of ((4pm 11pm 6)) MeV. Assuming the (X_2) as a (D^*bar{D}^*) molecular state, we calculate its hidden charm decay (X_2 rightarrow pi ^+ pi ^- eta _{c}) via box loop diagram using an effective Lagrangian approach. To investigate the dependence of the decay width on the molecular structure, we consider four different phase angles: (theta =0), (pi /6), (pi /4), and (pi /2). The decay width is found to be sensitive to the mass of the (X_2). The decay partial widths are predicted to be on the order of 1 keV. We expect that the present calculations, performed in the molecular framework, would provide useful guidance for future experimental studies.

In this article, we investigate the bound orbits of the timelike particles and the gravitational waveforms emitted from these orbits around a renormalization group improved Kerr black hole in the framework of the asymptotic safety approach. The running Newton coupling in the metric is characterized by two free quantum parameters ((omega ,,gamma )) arising from the non-perturbative renormalization group theory and the appropriate cutoff identification, respectively. As expected, the radii of the horizon, the marginally bound orbits and the innermost stable orbit are all decrease as the quantum parameters increase. Under the extreme mass-ratio inspirals approximation the deviation of gravitational waveforms radiated by the periodic orbits from those in the classical Kerr background increases with the two quantum parameters. However, this effect is much smaller in the retrograde case compared to the prograde case. Especially, by comparing the characteristic strain of those gravitational wave with the sensitivity curve of several potential detectors, we find that their characteristic frequencies can fall within the sensitivity ranges of several planned gravitational wave observatories, suggesting that such signals may be detectable with sufficient instrumental sensitivity.

We produce the gravitational waveforms for the extreme mass ratio inspiral systems (EMRIs) of binary stars moving around central supermassive black hole (SBH), or called B-EMRIs. We calculate the external orbits of the binary stars via the commonly used Hamilton–Jacobi (HJ) approach, and calculate the internal orbits of the binary stars via Lagrangican approach. To improve accuracy we adopt the quadrupole-octupole expression of gravitational wave (GW) and study the contribution of radiation reaction. Compared to the waveforms of EMRIs, there are higher frequency oscillations superposed on the waveforms of B-EMRIs. We perform frequency spectrum analysis of the GW waveforms, and find that higher frequency signals give their prominency in the waveforms of B-EMRIs. To obtain high precise result for future observation of GWs from space-based detector, we take into account gravito-electromagnetic (GEM) force, and compare the waveforms of B-EMRIs with GEM effects against those of B-EMRIs without GEM effects and against those of EMRIs. The result of mismatch shows that the waveforms of B-EMRIs are credibly distinguishable by the space-based GW detectors when GEM force is considered.

In this paper, we investigate the dynamical evolution of the innermost stable circular orbit and light ring of a charged black hole under the influence of scalarization dynamics. This is achieved through a series of nonlinear simulations within the framework of the Einstein–Maxwell-dilaton theory. By combining these nonlinear simulations with a (3+1) approach to geodesics in the dynamical spacetime, we derive the conditions for determining the ISCO and light ring in such a dynamical spacetime. Our results demonstrate how the ISCO and light ring evolve as a ‘hairless’ charged black hole transitions to a scalarized state. Moreover, we find that black hole scalarization leads to an increase in the areal radii of both the ISCO and light ring. These findings provide new insights into black hole scalarization, particularly concerning the dynamical evolution of the ISCO and light ring in a dynamically evolving spacetime.

We investigate the evolution and formation of double-layered vacuum bubbles during cosmological phase transitions with multiple vacua. We employ lattice simulations to show that flyover transitions can produce double-layered vacuum bubbles by overcoming successive potential barriers, thereby suggesting a novel bubble vacuum configuration in cosmological phase transitions. The evolution of these bubbles, including wall acceleration, collisions, and the formation of trapped regions, is explored through numerical simulations. Our results show that the dynamics of double-layered bubbles differ significantly from standard single-wall bubbles, with implications for cosmological observables such as gravitational wave production and baryogenesis.

Studying heavy-quark hadrons is crucial due to the nonperturbative nature of low-energy QCD, with Heavy-Quark Symmetry (HQS) serving as a key framework for understanding their spin and flavor symmetries. However, a key issue is that the theoretically expected (B^{(*)}bar{K}) molecular states have not yet been observed, although they are considered the bottom-quark counterparts of the observed (bar{D}^{(*)}bar{K}) molecular states (corresponding to (D_{s0}(2317/2460)^{-})), which challenges the universality of HQS. The main goal of this work is to search for the theoretically predicted (Bbar{K}) and (B^{*}bar{K}) molecular states, namely (B_{s0}^{*}(5725)) and (B_{s1}^{*}(5778)), via the reactions (K^{-}p rightarrow varLambda _{b}^{0} B_{s0}^{*}) and (K^{-}p rightarrow varLambda _{b}^{0} B_{s1}^{*}). Within an effective Lagrangian framework, we compute the relevant cross sections, considering t-channel (B^{(*)}) exchanges and (K^{-}p) initial-state interactions (ISI). The results show that the production cross sections of (B_{s0}^{*}(5725)) and (B_{s1}^{*}(5778)) can reach the order of 0.01 nb, and we suggest that experiments searching for (B_{s0}^{*}(5725)) are best performed at (P_{K^{-}} = 12.18~textrm{GeV}), while higher energies are most favorable for producing (B_{s1}^{*}(5778)). The ISI play a crucial role, as they not only significantly enhance the production cross sections of (B_{s0}^{*}(5725)) and (B_{s1}^{*}(5778)) (by roughly one order of magnitude) but also markedly affect the angular distributions of the produced particles. We also calculated the production cross sections of the conventional quark–antiquark states (B_{s0}^*(5700)) and (B_{s1}^*(5720)), which are found to be nearly the same as those of (B_{s0}^{*}(5725)) and (B_{s1}^{*}(5778)). Although their internal structures remain ambiguous, these results can inform future experimental searches at CERN and J-PARC.

The integrability or non-integrability of a spacetime usually refers to whether the motion of massive or massless particles in the spacetime is integrable or not. The standard black hole spacetimes such as the Schwarzschild and Kerr metrics are always integrable for both timelike and null geodesics. They belong to a first type of spacetime. However, the Melvin type spacetimes as a second type of spacetime are non-integrable, regardless of whether they are for massive or massless particle motion. In this paper, we discover the possibility of a third type of spacetime with non-integrable dynamics of timelike geodesics and integrable dynamics of null geodesics. In fact, conformal transformations may transform type one solutions into type three. This is due to the conformal factors preventing the separation of variables from the Hamilton–Jacobi equation and leading to the absence of a fourth constant of motion for the massive particle dynamics. Nevertheless, the massless particle motion still remains integrable in these metrics for any conformal factors because the conformal factors have no effect on the null geodesics whatsoever. The conformal Kerr metric is an example of the third type of spacetime. In addition to the conformal transformation method, other paths may yield the third type of spacetime. The Kerr–Bertotti–Robinson black hole metric and the accelerating Schwarzschild spacetime are two examples of non-conformal solutions that are also of type three.