The European Physical Journal C最新文献

We examine the stability of a spherically symmetric regular black hole when subjected to perturbations from a charged scalar field. This particular black hole is constructed by deforming the Minkowski spacetime. It has been observed that the charged superradiant instability arises only within a specific range of the deformation parameter, potentially resulting in an instability growth rate with a maximum magnitude of approximately (text {Im} (M omega ) sim 10^{-3}). This growth rate significantly exceeds the instability identified in ABG black holes discussed in prior research, suggesting a notable timescale for detecting this phenomenon in astrophysical scenarios. Additionally, we conduct a thorough investigation into how the three parameters of the model influence the onset and intensity of the instability. Our analysis offers further insights into the possible emergence of this instability in spherical regular black holes and its association with the nonlinear effects of the electromagnetic field.

We explore wormhole solutions sourced by Casimir energy density involving generalized uncertainty principle corrections within the framework of Rastall–Rainbow gravity. The questions of traversability and stability, as well as the presence of exotic matter, are carefully investigated. In particular, the stability issue is addressed via an approach that has not been previously employed in the context of wormholes. This method, which represents an improved version of the so-called Herrera cracking technique, has the potential to yield novel insights in the field of wormhole geometries.

The ATLAS tile calorimeter (TileCal) is the hadronic sampling calorimeter covering the central region of the ATLAS detector at the Large Hadron Collider (LHC). This paper gives an overview of the calorimeter’s operation and performance during the years 2015–2018 (Run 2). In this period, ATLAS collected proton–proton collision data at a centre-of-mass energy of 13 TeV and the TileCal was 99.65% efficient for data-taking. The signal reconstruction, the calibration procedures, and the detector operational status are presented. The performance of two ATLAS trigger systems making use of TileCal information, the minimum-bias trigger scintillators and the tile muon trigger, is discussed. Studies of radiation effects allow the degradation of the output signals at the end of the LHC and HL-LHC operations to be estimated. Finally, the TileCal response to isolated muons, hadrons and jets from proton–proton collisions is presented. The energy and time calibration methods performed excellently, resulting in good stability and uniformity of the calorimeter response during Run 2. The setting of the energy scale was performed with an uncertainty of 2%. The results demonstrate that the performance is in accordance with specifications defined in the Technical Design Report.

We report on the reactions (psi (3770)rightarrow bar{Omega }^+ bar{K} Xi ) and (psi (3770)rightarrow bar{Omega }^+ bar{K}Xi ^*(1530) ;(Xi ^*(1530)rightarrow pi Xi )), and calculate the mass distributions (frac{textrm{d}Gamma }{textrm{d}M_text {inv}(bar{K}Xi )}) and (frac{textrm{d}Gamma }{textrm{d}M_text {inv}(bar{K}Xi ^*)}), respectively. We obtain clear peaks corresponding to the (Omega (2012)). From the decay of (psi (3770)rightarrow bar{Omega }^+ bar{K}Xi ^*), we also get a second, broader, peak around (2035,mathrm MeV), which comes from the (Omega (2012)) decay to (bar{K}Xi ^*). This second peak is closely tied to the molecular picture of the (Omega (2012)) with the (bar{K}Xi ^*(1530)) and (eta Omega ) components. Its observation would provide a boost to the molecular picture of the (Omega (2012)).

We extend the formalism of tri-vector deformations to the full SL(5) exceptional field theory with no truncation assumed thus covering 11D backgrounds of any form. We derive explicit transformation rules for 11D supergravity component fields and prove that these generate solutions given the same algebraic conditions hold: generalized Yang–Baxter equation and the unimodularity condition.

In the framework of the relativized quark model, the calculation of spin-orbit interactions is improved by considering the contribution from the light-quark cluster in a singly heavy baryon. It modifies the energy level splitting of the orbital excitation significantly and causes the emergence of fine structures for (Sigma _{Q}), (Xi '_{Q}) and (Omega _{Q}) baryons. Based on this improvement, we systematically analyze the fine structures and retest the heavy quark dominance mechanism. This mechanism is found to be violated in the 1P-wave states of the (Sigma _{c}), (Xi '_{c}) and (Omega _{c}) baryons although it remains effective overall, which may help to understand the nature of the heavy quarks and strong interactions. With the predicted fine structures, we make the precise assignments of those observed heavy baryons which once could not be accurately explained due to their close mass values. The method used in this work is instructive and applicable for the study of more complex exotic hadrons, such as the heavy tetraquarks and pentaquarks.

In the context of braneworld scenarios, the real scalar field plays a crucial role by providing thickness for brane. In this work, we investigate a codimension-one thick brane within the framework of f(R, Q, P) gravity, where R represents the curvature scalar, while (Q=R_{mu nu }R^{mu nu }) and (P=R_{mu nu alpha beta }R^{mu nu alpha beta }) are quadratic geometric invariants. Our interest is to investigate the influence of these invariants on the scalar field solution and the energy density of the brane. Furthermore, we analyze the localization of spin 1/2 fermions and the gravitino by employing a Yukawa-like coupling with the scalar field background. Such a coupling is able to produce a normalizable zero-mode for both fields.

Proton–proton collision data recorded by the ATLAS detector in 2011, at a centre-of-mass energy of 7 TeV, have been used for an improved determination of the W-boson mass and a first measurement of the W-boson width at the LHC. Recent fits to the proton parton distribution functions are incorporated in the measurement procedure and an improved statistical method is used to increase the measurement precision. The measurement of the W-boson mass yields a value of (m_W = 80{,}366.5 pm 9.8~(text {stat.}) pm 12.5~(text {syst.})) MeV (= 80{,}366.5 pm 15.9) MeV, and the width is measured as (Gamma _W = 2202 pm 32~(text {stat.}) pm 34~(text {syst.})) MeV (= 2202 pm 47) MeV. The first uncertainty components are statistical and the second correspond to the experimental and physics-modelling systematic uncertainties. Both results are consistent with the expectation from fits to electroweak precision data. The present measurement of (m_W) is compatible with and supersedes the previous measurement performed using the same data.

In this work, we calculated the form factors of the weak decay process (varLambda _b^0 rightarrow varLambda _c(2595)^+), where the final charm baryon represents an excited state with spin-parity (frac{1}{2}^-). Utilizing the light-cone QCD sum rules approach, we incorporated the contributions of the lowest two charm baryon states: the ground state (varLambda _c) with (J^P=frac{1}{2}^+) and the excited state (varLambda _c(2595)^+) with (J^P=frac{1}{2}^-) in the hadronic representation of the (varLambda _b rightarrow varLambda _c(2595)^+) transition correlation function. This approach allows us to extract the form factors of the (varLambda _b^0 rightarrow varLambda _c(2595)^+) from (varLambda _b^0 rightarrow varLambda _c^+) transition. During the light-cone QCD sum rules procedure, we employed the light-cone distribution amplitudes (LCDAs) of the (varLambda _b) baryon. Furthermore, by combining these form factors with the helicity amplitudes of the bottom baryon transition matrix elements, we calculated the differential decay widths for the processes (varLambda _b^0 rightarrow varLambda _c(2595)^+ell ^-bar{nu }_ell ) and provided the optimal choice of the interpolating current for (varLambda _c) in this process. Additionally, within the lifetime of (varLambda _b^0), we obtained the absolute branching fractions for the semileptonic decays (varLambda _b^0 rightarrow varLambda _c(2595)^+ ell ^- bar{nu }_ell ). With the branching fractions of (varLambda _b^0 rightarrow varLambda _c(2595)^+ ell ^- bar{nu }_ell ) calculated in this work, we also determined the parameter (mathcal {R}(varLambda _c(2595)^+)) which tests the lepton flavor universality. This parameter is defined as the ratio of branching fractions (mathcal {B}r(varLambda _b^0 rightarrow varLambda _c(2595)^+tau ^-bar{nu }_tau )) and (mathcal {B}r(varLambda _b^0 rightarrow varLambda _c(2595)^+mu ^-bar{nu }_mu )). Our results provide a valuable theoretical test for these decay channels and offer insights into the LCDAs of bottom baryons, paving the way for further in-depth investigations.

The characteristics of wormhole models in the context of the de Rham–Gabadadze–Tolley-like massive gravity theory are examined in this article. Dark matter density profiles of Thomas Fermi and Einasto spike are used to find the wormhole shape functions. By exploiting these formed shape functions, we create a wormhole geometry that connects asymptotically flat regions of spacetime while fulfilling all necessary requirements. Through a comprehensive analytical and graphical investigation, we explore the characteristics of exotic matter in these wormhole structures and examine their material composition within the context of energy conditions. The volume integral quantifier is used to quantify the exotic matter. We also discuss the phenomena of the complexity factor for all wormhole models and conclude that it approaches zero for increasing values of the radial coordinate, indicating the homogeneity of the energy density and the isotropic behavior of the pressure. Moreover, the repulsive nature of these wormhole solutions, a critical characteristic for their possible traversability is revealed by our analysis of the anisotropy parameter.