The European Physical Journal C最新文献

The complex phases (phi _d) and (phi _s), associated with the mixing between neutral (B_q^0) and (bar{B}_q^0) mesons ((qin {d,s})), are key observables to test the Standard Model and search for contributions from new physics. They are conventionally determined from the measurements of mixing-induced CP violation in the decays (B_d^0rightarrow J/psi K^0), (B_s^0rightarrow J/psi phi ) and (B_s^0rightarrow D_s^+D_s^-). To reach the highest possible precision on (phi _d) and (phi _s), it is crucial that corrections from next-to-leading order effects – primarily associated with penguin decay topologies – are accounted for. The strategy adopted in this paper uses the SU(3) flavour symmetry of QCD to relate the unknown contributions from penguin topologies to their counterparts in suitably-chosen control modes, where their effects are enhanced. Utilising new CP asymmetry measurements from LHCb on the decays (B_s^0rightarrow D_s^+D_s^-), (B_d^0rightarrow D^+D^-), (B^+rightarrow J/psi K^+) and (B^+rightarrow J/psi pi ^+), as well as from Belle-II on the decay (B_d^0rightarrow J/psi pi ^0), we present the current state-of-the-art picture on controlling the penguin contributions and extract (phi _d) and (phi _s) from the corresponding observables. We explore the prospects for the end of the Belle-II and HL-LHC flavour physics programmes, and demonstrate the importance of measuring the control modes with future data.

Standard Model extensions that yield observable neutrino magnetic moments typically also induce large neutrino masses, incompatible with experimental limits. This tension motivates the search for mechanisms that naturally decouple magnetic moments from mass generation without requiring fine-tuning. In this letter, we propose a novel mechanism for generating Dirac and Majorana neutrino magnetic moment, in which the associated mass contribution is forbidden by (SU(2)_L) invariance. By carefully selecting the (SU(2)_L) representations connecting the neutrino to the loop diagram, we ensure that only the effective dipole operator involving the non-Abelian part of the photon – the neutral (SU(2)_L) gauge boson – is generated. Crucially, the corresponding mass diagram, obtained by removing the external gauge boson leg, vanishes. We provide explicit UV completions that implement this mechanism and yield neutrino magnetic moments within the sensitivity of current and future experiments.

We investigate the greybody factor for the accelerating rotating Bañados–Teitelboim–Zanelli (BTZ) black hole in (2+1)-dimensional spacetime. Due to the non-separability of the Klein–Gordon equation induced by the acceleration parameter, we employ an azimuthal-average approximation to derive an effective potential for massless scalar fields. In the low-frequency limit, we solve the radial equation using matched asymptotic expansions near the horizon and in the far region, accounting for rotation via the horizon angular velocity. Our results yield a power-law scaling for the greybody factor, (Gamma (omega ) propto (omega - m Omega _H)^{2lambda - 1}), where (lambda = sqrt{mu ^2 ell ^2 + 5/4}), highlighting deviations from pure blackbody radiation. We discuss implications for Hawking radiation, superradiance in the regime (omega < m Omega _H), and the role of acceleration in modifying black hole thermodynamics.

The gravitational weak lensing of neutrinos in the presence of a Schwarzschild black hole surrounded by a Dehnen-type dark matter halo is investigated. The event horizon structure is explored, and the existence of the BH is studied in two different slices of the parameter space. Additionally, we derive analytic expressions for the oscillation phase and transition probabilities for both radial and non-radial neutrino propagation. Finally, we use a two-flavor toy model, and numerically analyze how the dark matter halo parameters as density and scale radius, affect oscillation probabilities and examine the role of decoherence. The results show that the presence of a dark matter halo modifies the oscillation phase and damping factor, leading to measurable deviations from the standard Schwarzschild BH case. These findings suggest that neutrino oscillations could, in principle, serve as a probe for dark matter distributions around compact astrophysical objects.

The higher-order corrections for the SM-like Higgs boson mass and the trilinear Higgs self-couplings in the Next-to-Minimal Supersymmetric extension of the Standard Model (NMSSM) with Inverse Seesaw Mechanism are significant and highly correlated. We present here the full one-loop corrections to the trilinear Higgs self-couplings supplemented by the dominant top-Yukawa and strong coupling induced two-loop corrections from our previous calculations in the complex NMSSM. These corrections are performed consistently with the corresponding Higgs boson mass corrections. We discuss in detail the new effects from the extended neutrino and sneutrino sectors on both the trilinear Higgs self-couplings and the SM-like Higgs boson mass. When compared to the case of the NMSSM without Inverse Seesaw Mechanism, the new effects can be up to 10% for the effective SM-like trilinear Higgs self-couplings, and up to 4.5% for the SM-like Higgs boson mass for valid parameter points, i.e. points satisfying the Higgs data, the neutrino data, the constraints from the charged lepton flavor-violating decays, and the new physics constraints from the oblique parameters S, T, U. The new corrections are also included in the Higgs-to-Higgs decays for the heavy Higgs states and implemented in the new version of the Fortran code NMSSMCALC-nuSS.

In this work, we distinguish the isospin unambiguously to construct the diquark–diquark–antiquark type five-quark currents with the isospin (I=1/2), and study the (uudcbar{c}) pentaquark states with the QCD sum rules systematically for the first time. Then we obtain the mass spectrum of the diquark–diquark–antiquark type (uudcbar{c}) pentaquark states with the isospin-spin-parity (IJ^P=frac{1}{2}{frac{1}{2}}^-), (frac{1}{2}{frac{3}{2}}^-) and (frac{1}{2}{frac{5}{2}}^-), and make possible assignments of the (P_c(4312)), (P_c(4337)), (P_c(4380)), (P_c(4440)) and (P_c(4457)) states. As a byproduct, we obtain the lowest hidden-charm pentaquark state which lies just above the (bar{D}Lambda _c) threshold.

Investigating the impact of dark matter on gravity near black holes (BHs) using observational evidence and theoretical analysis is a critical area of relativistic astrophysics. Therefore, in this manuscript, we examine the behavior of test particles in the vicinity of magnetized Schwarzschild BHs within the framework of scalar-vector-tensor gravity (STVG) theory. We assume that the BH is surrounded by a magnetosphere modeled using the parabolic magnetic field solution. We study the circular motions of test particles near BHs and calculate the corresponding effective potential, accounting for the MOG interaction and the magnetic field’s influence on particle geodesics. In addition, we analyze the stability of circular orbits by evaluating the effective potential, angular momentum, and the particle’s energy. We demonstrate how MOG interactions and the magnetic field affect the location of the innermost stable circular orbits (ISCO). Using the Navikov–Thorne thin accretion disk model, we studied how MOG interactions and the magnetic field affect energy efficiency, energy flux, and temperature distribution. Moreover, we investigate the collision of magnetized particles near our spacetime geometry under the influence of MOG and magnetic fields. Finally, we study the trajectories of charged particles under the influence of MOG interactions and a magnetic field and present our conclusions in the final section.

We develop worldline formulations of covariant fracton gauge theories. These are a one-parameter family of gauge theories of a rank-two symmetric tensor field, invariant under a scalar gauge transformation involving a double derivative. These theories, which can be interpreted as linearized gravity theories invariant under longitudinal diffeomorphisms, provide a covariant framework for studying Lorentz-breaking fracton quasiparticles, which are excitations with restricted mobility due to dipole-moment conservation. We construct three worldline models. The first two are obtained by deducing their constraint structure directly from the spacetime gauge transformations. By applying BRST quantization, we show that these models reproduce the BV spectrum and the associated BRST transformations of two specific fracton theories. The third model is defined as a deformation of the second one: although free, it is analyzed by drawing inspiration from the standard treatment of interacting worldline systems, and is shown to capture almost the entire family of covariant fracton theories. Finally, we discuss the gauge-fixing, comparing the BV-BRST spacetime perspective with the worldline analogue of the “Siegel gauge” employed in string field theory.

We prove an infinite sequence of inequalities among scalar polynomial invariants of symmetric rank-2 tensors of Segre types A1, A3, and B. In particular, these inequalities apply to the Ricci tensor and the energy-momentum tensor. If at least one of them is violated by the Ricci tensor, then the Einstein equations force violation of all classical energy conditions. In addition, we use one of the inequalities to generalize the known relation between the second Ricci invariant and the Kretschmann scalar.

Using the next-to-leading order (NLO) coefficient functions for exclusive electroproduction of heavy vector mesons derived in our previous work, we perform various phenomenological studies of exclusive electroproduction in ep collisions relevant for both the existing measurements from HERA, and the forthcoming Electron-Ion Collider (EIC). We compare our cross-section results to HERA data across a broad range of photon virtualities (Q^2) and (gamma ^* p) centre-of-mass energies, provide predictions for upcoming EIC measurements and conclude with a discussion on the necessity of resumming logarithmically enhanced contributions in (J/psi ) electroproduction.