The European Physical Journal C最新文献

We study the strong decay of (D_{s0}^*(2317)^+) to (D_s^+ pi ^0) considering the coupled channels of (D^0 K^+, D^+ K^0, D_s^+ eta ) and (D_s^+ pi ^0) within a picture for the interaction based on the local hidden gauge approach. We also address the problem of the radiative decay to (D_s^{*+} gamma ), using the same information obtained from the molecular picture. We obtain a strong width of the (D_{s0}^*(2317)^+) of about (77 ,mathrm keV) from coupled channels interaction and a radiative decay of about (1.7 ,mathrm keV). We also show that the extra consideration of (pi ^0-eta ) mixing can double the strong decay width to values around (140 ,mathrm keV). The anomalous terms for the radiative decay are considered for the first time, but they are found negligible. We make a thorough discussion of this and other results to the light of the recent measurement of Belle for the ratio of these two decay modes, and make a call for the precise measurement of the two decay widths independently to clarify the present situation concerning the nature of the (D_{s0}^*(2317)^+) state.

The aim of this paper is to investigate the stability and existence of the closed Einstein Universe (EU) under linear homogeneous perturbations within the framework of ( f(mathcal {R}, phi , chi ) ) gravity. For this, we consider a closed Friedmann–Roberson–Walker universe filled with isotropic matter. Perturbations are imposed on the matter parameters and on the scale factor. We systematically derive the static and perturbed field equations for scenarios with and without conservation of the energy–momentum tensor and examine the associated stability regions through selected models in (f(mathcal {R},phi ,chi )) gravity. The graphical analysis shows that for suitable choices of model parameters such as ( alpha ), b and scalar field (phi _o), the stable regions of the Einstein universe can be obtained in this theory of gravity. Significant differences in stability regions are observed for scalar fields governed by standard kinetic energy and for those characterized by negative kinetic energy. The scalar field and coupling parameters play a key role in the existence of stable regions of the Einstein universe.

Within general relativity, we study spherically symmetric configurations with wormhole topology consisting of spinor fields and a Maxwell electric field. For such a system, we construct complete families of regular asymmetric solutions describing wormholes connecting two identical Minkowski spacetimes. The physical properties of such systems are completely determined by the values of three input quantities: the throat parameter, the spinor frequency, and the coupling constant. Depending on the specific values of these parameters, the configurations may have essentially different characteristics, including negative ADM masses.

Focusing on the description of cosmic evolution at late times, this study examines a generalized holographic dark energy (HDE) framework constructed via a polynomial expansion in the Hubble parameter, which includes contributions proportional to (H^{2},) (H^{4},) and (H^{6},) introduced through a variable parameter within the standard holographic formula. The analysis is carried out in the context of a spatially flat Friedmann–Lemaître–Robertson–Walker (FLRW) Universe, consisting of non-interacting matter together with the HDE fluid. We obtain the full set of Friedmann equations to investigate cosmic evolution and then analyze the system to determine whether thermodynamic (P{-}v) type phase transitions can occur.

Light-cone perturbation theory is a powerful tool for calculating high-energy scattering amplitudes, particularly for quantum particles such as electrons, photons, or protons scattering off heavy nuclei, a process analogous to potential scattering. Central to these computations are the light-cone wave functions of incoming and outgoing particles, representing the projection of dressed initial and final states onto partonic Fock states. The dressed states are obtained by applying an evolution operator in the Dirac picture to bare partonic states, which may be interpreted physically as a time evolution from preparation to interaction. In standard approaches, a non-unitary operator is used, and proper normalization is imposed a posteriori. Here, we systematically develop perturbation theory from a perturbatively unitary evolution operator, using adiabatic switching to regularize the infinite-time limits. This provides a theoretically coherent framework for organizing calculations, reproducing known results entirely diagrammatically without enforcing unitarity by hand. We illustrate the method with a simple quantum mechanical model, enabling calculations to arbitrary perturbative orders, and then evaluate wave functions in field theories quantized on the light cone, focusing on a massive scalar theory with cubic interaction at one-loop accuracy.

The Run 3 of the LHC brings unprecedented luminosity and a surge in data volume to the LHCb detector, necessitating a critical reduction in the size of each reconstructed event without compromising the physics reach of the heavy-flavour programme. While signal decays typically involve just a few charged particles, a single proton–proton collision produces hundreds of tracks, with charged particle information dominating the event size. To address this imbalance, a suite of inclusive isolation tools have been developed, including both classical methods and a novel Inclusive Multivariate Isolation (IMI) algorithm. The IMI unifies the key strengths of classical isolation techniques and is designed to robustly handle diverse decay topologies and kinematics, enabling efficient reconstruction of decay chains with varying final-state multiplicities. It consistently outperforms traditional methods, with superior background rejection and high signal efficiency across diverse channels and event multiplicities. By retaining only the most relevant particles in each event, the method achieves a 45% reduction in data-size while preserving full physics performance, selecting signal particles with 99% efficiency. We also validate IMI on Run 3 data, confirming its robustness under real data-taking conditions. In the long term, IMI could provide a fast, lightweight front-end to support more compute-intensive selection strategies in the high-multiplicity environment of the High-Luminosity LHC.

Recent observations from the Atacama Cosmology Telescope (ACT), especially when combined with DESI baryon acoustic oscillation data, indicate a scalar spectral index ( n_s ) higher than the value reported by Planck 2018, placing tension on universal inflationary attractor models. Motivated by this discrepancy, we investigate the inflationary predictions of the (beta )-exponential potential, ( V(phi )=V_0left( 1-lambda beta phi /M_pright) ^{1/beta }) considering both minimally and non-minimally coupled realizations. This potential generalizes standard exponential inflation and naturally arises in braneworld scenarios. We derive analytical expressions for the slow-roll parameters and inflationary observables using a perturbative expansion in the non-minimal coupling (xi ), and validate these results through numerical calculations. In the minimally coupled case, the model predicts ( n_s simeq 0.976 ) and ( r simeq 0.035 ) for (N=50) and moderate values of (beta ), remaining compatible with ACT+DESI (P-ACT-LB) constraints at the (1sigma ) level while yielding a spectral tilt larger than the universal attractor prediction. Introducing a small non-minimal coupling significantly improves agreement with observations by suppressing the tensor-to-scalar ratio while preserving the enhanced scalar tilt. For (N=60 ), ( lambda sim 0.3!-!0.5 ), and ( beta sim mathcal {O}(1!-!5) ), the non-minimally coupled model yields ( n_s simeq 0.974!-!0.976 ) and ( r lesssim 0.03 ), comfortably consistent with ACT, DESI, and BICEP/Keck bounds. Our results show that the (beta )-exponential potential, especially when implemented with a non-minimal coupling, exhibits good agreement with the latest CMB observations. Our inflationary predictions of the non-minimal model of (n_s) and r confirming the leading-order contributions in (xi ) are sufficient to capture the essential features of both r and (n_s) in observationally relevant regimes.

The Jiangmen Underground Neutrino Observatory (JUNO) employs a 20 kt liquid scintillator (LS) detector located 700 m underground. To meet its physics objectives, the LS must achieve an ultra-low (^{238})U/(^{232})Th content of 10(^{-17}) g/g. Given that airborne dust exhibits radioactivity about 12 orders of magnitude higher, exceptional cleanliness is essential during on-site installation. The total permissible dust mass in the 20 kt LS is only about 8 mg. To attain this, the acrylic vessel interior must comply with class 1000 cleanliness. Pre-filling water spray cleaning improves cleanliness by roughly two orders of magnitude, requiring the overall environment to be maintained between class 10,000 and 100,000. At JUNO, a cleanroom management system has been implemented across the 120,000 m(^3) underground experimental hall. Since May 2022, continuous laser particle monitoring has consistently achieved an average cleanliness class of 74,000. Furthermore, we developed a method to directly measure (^{238})U/(^{232})Th deposition rates on detector surfaces. Using ICP-MS, sensitivity reaches sub-ppt levels ((<10^{-12}) g/g), enabling effective cleanliness control and assessment of external contamination during detector construction.

We consider models of gauge mediated supersymmetry breaking involving the messenger fields from the adjoint representation of MSSM’s gauge group. In addition, we include the non-holomorphic (NH) terms induced by the supersymmetry breaking and involve them in the renormalization group evolution in calculating the low scale implications. With the NH contributions, the stau mass-square can be driven to the positive values in the renormalization group evolution, even if the hypercharge interactions are small. We realize that the NH contributions can be as high as about 25 TeV in the right-handed stau mass. Despite such large contributions, the effects from the NH terms in sparticle mixing can lower the overall NH contributions in the mass eigenstates by about 5 TeV. Similarly, the sbottom mass can differ by about 6–7 TeV, and the stop mass by about 15 TeV, when the NH terms are largely induced. Their contributions in the sparticle masses lead to significant impacts in the SM-like Higgs boson as well. The NH contributions can yield 80 GeV heavier SM-like Higgs boson. In a small region of the parameter space, we also observe negative NH contributions in the masses such that the sparticles can be lighter about 1 TeV while the Higgs boson mass can be lowered by about 20 GeV in this region. The NH contributions can have interesting consequences in the muon anomalous magnetic moment (muon (g-2)). The NH terms reduce the supersymmetric contributions to muon (g-2) by leading to heavier mass spectrum. In addition, the NH mixing term in smuons lowers further such that the light sleptons, neutralinos and charginos can still be consistent with the latest updates in muon (g-2) measurements.

The CREDO-Maze project, which is being carried out at the University of Łódź, has at least two important objectives. The first is purely scientific. It involves searching for the Cosmic Ray Ensemble, more specifically, identifying long-range correlations between extensive air showers. The distances involved can be hundreds or even thousands of kilometres. Observing these hypothetical phenomena would necessitate a significant revision of our views on the universe and its origins. The second goal is equally important and has an educational focus. The aim is to establish an experimental base that will enable a large number of young people to learn about modern physics and become familiar with scientific methods, thereby stimulating their interest in science – particularly physics. The project is based on Linsley’s concept of a distributed air shower array, but on a global scale. This involves installing small particle arrays in numerous locations via a network of high schools. In this paper, we discuss the design of a single detector and the ’minimal’, local (school) shower array, as well as the structure of the entire CREDO-Maze network. We present the results of some detector tests, as well as selected results of the apparatus operating in atypical geometries. These results confirm the validity of our assumptions and demonstrate the significant potential of the apparatus for non-trivial and unusual measurements, including the search for Cosmic Ray Ensembles.