The European Physical Journal C最新文献

A cryogenic detector system based on two 3.3 kg high-purity CsI crystals was developed and characterized at approximately 95 K. Each crystal was coupled to dual-ended 3-inch photomultiplier tubes (PMTs) for scintillation readout. The measured light yields were (28.7 pm 0.9) and (29.3 pm 1.0) photoelectrons per keV electron-equivalent (PE/keV(_{ee})) for the two crystals, with corresponding energy resolutions of 7.2% and 7.7% (FWHM) at 59.6 keV. The detector demonstrated excellent spatial uniformity, low intrinsic radioactivity, and stable operation over a continuous one-month period. Optical photon simulations using Geant4 reproduced the observed light collection trends, providing guidance for detector optimization. These results establish cryogenic pure CsI as a scalable technology for low-threshold rare-event searches.

We present a systematic post-Newtonian treatment of binary charged black holes immersed in external magnetic fields within the framework of Einstein–Maxwell theory. By incorporating a uniform external magnetic field into the two-body Lagrangian expanded to first post-Newtonian order, we derive the complete equations of motion that capture both gravitational and electromagnetic interactions. The magnetic Lorentz force fundamentally alters the orbital dynamics, breaking the conservation of linear and angular momentum and inducing transitions from planar to three-dimensional trajectories. Through numerical integration of these equations, we compute the resulting gravitational waveforms and characterize the distinctive magnetic field signatures through time-domain and frequency-domain analysis. Our results demonstrate that strong background magnetic fields can substantially modify the orbital evolution and leave distinctive signatures in the gravitational wave signals. These findings provide a promising avenue for detecting charged black holes and probing magnetic field environments through gravitational wave observations.

In asymptotically anti-de Sitter (AdS) spacetime, we consider a real massive scalar field in the Einstein–Maxwell-Scalar (EMS) model and examine both scalar-hairy black hole solutions induced by the nonminimal coupling to the Maxwell field and tachyonic-hairy solutions driven by the scalar potential. When the scalar potential vanishes, scalar-hairy black holes emerge with profiles and properties similar to those observed in flat spacetime. The presence of the scalar potential additionally induces tachyonic-hairy solutions, leading to the coexistence of these two distinct hairy phases in different regions of the parameter space. The phase diagram reveals a first-order phase transition line between the tachyonic-hairy and scalar-hairy phases, originating at a critical point in the extreme temperature and chemical potential regime. Our detailed analysis shows that this phase transition is directly associated with the self-overlap region of the scalar-hairy phase and its start point. Moreover, increasing the coupling strength (lambda ) shifts the critical point to higher temperature and chemical potential.

Probing extra polarizations in gravitational waves (GWs) with space-based detectors is the most direct method for testing theories of gravity. In this paper, by employing the second-generation time-delay interferometry (TDI) to cancel out the laser frequency noise in a rotating and flexing configuration with arm lengths varying linearly in time, and using the parametrized post-Einstein (ppE) waveform, we study the detectors’ constraint ability on extra polarizations, and explore the impacts of TDI on the constraint of polarizations. We find that the constraints on extra polarizations are significantly weaker than the tensor mode, especially for the scalar breathing and scalar longitudinal modes. However, the detectability improves with increasing gravitational-wave source mass for the vector mode. Since the detector’s capability to constrain polarizations depends mainly on the signal-to-noise ratio (SNR), it has minimal impact on the SNR when applying the TDI method to the signal response. Therefore, the use of the TDI method does not significantly affect the extra polarization constraints in practical GW detection.

Yukawa gravity provides a generalized framework for modeling gravity modification. We investigate the rotation curve profiles of spiral galaxies under Yukawa-like theories governed by the coupling strength (beta ) and the interaction range (lambda ). We develop a unified analytical and numerical framework to calculate rotational velocities under Yukawa gravity, which includes contributions from all major galactic components: stellar bulge, disk, dark matter (DM) halo, and central supermassive black hole. The calculations show that (beta ) and (lambda ) strongly influence velocity distributions by shifting peaks, creating double-peaked structures, or enhancing dark matter dominance in the bulge or disk. To assess observational implications, we perform Bayesian analyses using data from the Milky Way (MW) and Andromeda (M31), which offer complementary characteristics: MW provides precise velocity profiles across multiple scales, while M31 includes broader morphological constraints. We examine four scenarios: Yukawa gravity without dark matter, dark matter with non-trivial coupling, fully modified gravity, and standard Newtonian gravity. Results show that MW models with (lambda < 1) kpc yield high Bayes factors but risk overfitting, as dark matter mimics baryonic kinematics, while M31’s photometric priors from conjugate observations mitigate this, yielding robust parameter estimates. However, in M31, Bayes factors favor Newtonian gravity, suggesting that current data lack the precision to resolve more complex models. This finding highlights two key needs: (i) realistic, physically or empirically informed priors to avoid biased constraints, and (ii) high-precision data with independent photometry to guard against overfitting. Our framework offers a scalable approach for testing gravity with large galactic rotation curve datasets.

Gamma-ray bursts (GRBs) are the most energetic electromagnetic explosions in the universe. Recently, the Large High Altitude Air Shower Observatory (LHAASO) reported the breakthrough observation of GRB 221009A with gamma-ray energies beyond 13 TeV. This discovery, together with the previous GRB detection well above 100 GeV, confirms the production of very-high-energy (VHE, (gtrsim 100) GeV) radiation which might be a common component of all bright GRBs. It is reasonable to expect that bright GRBs are important targets for ground-based gamma-ray experiments. In this work, we estimate the detection rate for current and upcoming ground-based gamma-ray observatories including LHAASO, Large Array of Imaging Atmospheric Cherenkov Telescopes (LACT) and the Southern Wide-field Gamma-ray Observatory (SWGO) under two emission models with GRB 221009A as the template: first, that they all share the same intrinsic VHE spectral shape; second, they have the same environmental parameter and electron spectral index, governing their synchrotron self-Compton (SSC) emission. Using the long GRB luminosity and redshift distribution function obtained from the Fermi-GBM GRB samples, and accounting for the cosmological effects and extra-galactic background light (EBL) absorption, we derive the expected VHE flux at Earth. The sensitivity analysis for LHAASO, the upcoming LACT, and SWGO to evaluate their detection potential across specific redshift and luminosity ranges has been performed. The corresponding 5(sigma ) detection rates of 221009A-like GRBs for the two emission models are: LHAASO, 0.04–0.05 (hbox {yr}^{-1}); LACT, 0.03–0.06 (hbox {yr}^{-1}); SWGO, 0.2–0.4 (hbox {yr}^{-1}). These rates can vary by up to (approx 24%) due to different EBL models.

In this work, we have considered a minimally modified gravity theory that effectively reproduces VCDM-like behavior to investigate its cosmological implications. The model parameters are constrained using a combination of CC, RSD, DESI BAO DR2, and Union3 datasets. The model parameters are constrained using an MCMC framework, ensuring a robust estimation of credible intervals. We examine both background and perturbation-level observables, analyzing the Hubble parameter, deceleration parameter, effective equation of state, distance modulus, and the growth rate of cosmic structures through the (fsigma _8(z)) observable. Our results show that the model successfully reproduces the observed expansion history, featuring a smooth transition in the Hubble evolution around (z simeq 0.3), and consistent behaviour of cosmological parameters. The model outperforms (Lambda )CDM in the statistical comparisons for the full dataset combination (CC+RSD+DESI DR2+Union3). These results highlight the potential of minimally modified gravity theories with VCDM-like dynamics as consistent and competitive alternatives to the standard cosmological paradigm.

In this draft, we investigate the propagation and observational imprints of gravitational waves (GWs) from compact binary inspirals in f(T) theory, a torsion based extension of general relativity (GR). In this theory, modifications to the underlying dynamics alter the effective luminosity distance of GWs relative to the standard electromagnetic counterpart, introducing a redshift dependent damping effect. We consider exponential corrections of f(T) theory to analyze the impact on the propagation of tensor modes and the corresponding GW signals, by using post-Newtonian waveform templates and Fisher matrix forecasts. We assess the ability of current and future ground based interferometers, such as Advanced LIGO (aLIGO) and the Einstein Telescope (ET), to constrain the additional parameters introduced by these models. Current detectors already constrain deviations from GR, while next-generation observatories will improve these bounds by up to two orders of magnitude, underscoring the power of GW observations to test torsion based gravity models.

We explore the features of a thick braneworld model in five dimensions governed by a Einstein–Gauss–Bonnet gravity with a non-minimal coupling to a dynamical scalar field. We consider two possible scalar-GB coupling function (chi (phi )), one parity-even and another parity-odd function of the scalar field (phi ). For both choices, the scalar-Gauss–Bonnet non-minimal coupling produces a warped asymptotically (AdS_5) spacetime even in the absence of a bulk cosmological constant. Outside the brane core, a negative cosmological constant is bounded by the scalar-GB coupling function. For a thick 3-brane configuration, we found solutions with localized brane energy density and pressure that dynamically produce a bulk cosmological constant. The corresponding scalar field solutions exhibit a non-topological (domain wall) behavior. In order to probe the 3-brane stability solution, we employed a perturbative analysis, by perturbing the thick brane solutions up to first-order. The Kaluza–Klein (KK) tensorial gravitational modes possess a localized massless mode and a tower of non-tachyonic diverging massive modes, what renders the solutions stable at least at the perturbative level.

In this work, we study two scalar field driven dark energy models characterized by the axion potential and the inverse power-law potential, each coupled to dark matter through momentum exchange. By formulating the dynamics as an autonomous system, we identify the equilibrium points and analyze their stability. To constrain these models, we utilize observational data from Pantheon Plus Type Ia Supernovae, DES Y5, DESI DR2 BAO, and Planck 2018 CMB compressed likelihood, employing Markov Chain Monte Carlo (MCMC) methods. Both potentials exhibit weak to strong preference over the (Lambda )CDM model, with a particularly strong preference for the momentum-coupled scenario when Supernova data are included in the analysis. Furthermore, we find the coupling parameter to be negative, with no lower bound, for both potentials. This finding agrees with previous studies and suggests that momentum-exchange coupling between the dark sectors cannot be ruled out. From the stability analysis, we observe that for both potentials, the late-time attractor corresponds to a dark energy–dominated phase, and the scalar field can behave as a stiff fluid during the early epoch. According to the model selection criteria, the inverse power-law potential is favoured over the axion potential.