The European Physical Journal C最新文献

In physics geometrical connections are the mean to create models with local symmetries (gauge connections), as well as general diffeomorphisms invariance (affine connections). Here we study the irreducible tensor decomposition of connections on the tangent bundle of an affine manifold as used in the polynomial affine model of gravity (Castillo-Felisola et al. in Universe 11(3):102, 2025. https://doi.org/10.3390/universe11030102). This connection is the most general linear connection, which allows us to build metric independent, diffeomorphism invariant models. This set up includes parts of the connection that are associated with conformal and projective transformations.

We propose a simple, renormalizable scenario in which all of dark energy arises from a one-loop Coleman–Weinberg potential induced by a scalar field Yukawa-coupled exclusively to Standard-Model neutrinos. Classically, (V_{min }=0), but neutrino loops lift the vacuum by (rho _{text {DE}}=frac{y^{2}m_{nu }^{6}}{512pi ^{4}m_{phi }^{2}}), matching the observed dark energy scale for (yapprox 0.28m_{phi }/)eV and (m_{nu }sim 0.1,)eV. We detail cosmological tracking, demonstrate stability against neutrino clumping, and show that rapid scalar oscillations leave no detectable imprint on current neutrino-oscillation experiments—though they provide a clear target for future high-precision probes. Compared to other mass varying neutrino models, our framework employs only a renormalizable quadratic potential, avoids unnatural hierarchies, and makes concrete, testable predictions.

To date, wormholes have not been observed. Dynamic wormholes are difficult to detect due to their transient existence or extremely low spacetime curvature contrast, while static wormholes rely on “exotic matter” that violates the Null Energy Condition and lack direct theoretical support. This study explores the mechanism of dynamic wormhole formation via gravitational collapse of Bose–Einstein Condensate (BEC) dark matter in generalized Vaidya spacetime. Under specific conditions, the gravitational collapse of BEC dark matter interacts with gravitational fields to trigger abrupt changes in spacetime topology. This process depends on special parameters that are more likely to be satisfied in extreme environments. During the collapse, the condensate properties of BEC influence the evolution of spacetime curvature, and its intrinsic oscillatory behavior may facilitate the formation of dynamic wormholes. The research deduces function constraints that satisfy various energy conditions, constructs a dynamic wormhole form adapted to generalized Vaidya spacetime, and derives the Hawking radiation expression and mass function constraints by combining Lorentz-breaking quantum gravity theory. This mechanism confirms the feasibility of dynamic wormhole formation, provides a new perspective for understanding the behavior of dark matter under extreme gravity and the evolution of spacetime topology, and advances wormhole research toward the analysis of dynamic formation processes.

We propose a unified model of dark energy and inflation through the Markov–Mukhanov modification of the Einstein–Hilbert action, where the matter sector is coupled to gravity via a scalar coupling function depending only on the energy density of the matter content. We assume that the coupling function encodes the UV corrections to the standard model of cosmology and we determine the form of the coupling that allows for the dark energy component to be dynamical and act as the inflaton field in the early universe. Interestingly we show that our model, in order to account for inflation, prefers a dark energy equation of state with w close but not equal to (-1) in agreement with the latest DESI data.

We develop a unified dynamical systems framework for spatially flat FLRW cosmology in f(Q) gravity, covering all three connection branches using a single set of Hubble-normalised variables without fixing the function f(Q) a priori. This model-independent and connection-agnostic approach enables direct comparison across connection choices and uncovers structural features of the cosmological dynamics not visible in connection-specific formulations. While the existing works narrowly focus only on fixed point analysis, in our work we put special efforts to identify the invariant submanifolds, model-independent trajectories and physically viable regions of phase space across connections. For a broad class of viable f(Q) models, we establish the generic existence of de Sitter attractors and matter-dominated fixed points in the two branches of connection, offering a robust route to late-time acceleration without fine-tuning. We further identify an invariant submanifold that yields (Lambda )CDM-like background evolution despite underlying dynamics distinct from General Relativity, providing a geometric origin for cosmic acceleration distinguishable only at the perturbation level. We also derive a first integral on this submanifold, allowing analytic reconstruction of the dynamical connection and uncovering hidden conservation laws. Another key feature we found is that while trivial connections exhibit strong parameter dependence, the nontrivial branches often feature parameter-independent behaviours. We also study the variation of the effective gravitational coupling, (k_{text {eff}}), across branches and show how this can be constrained using astrophysical observations, which bridges theoretical viability with observational consistency in a novel way. Applying our framework to the illustrative model (f(Q)=alpha Q + beta (-Q)^n), we find late-time acceleration and (Lambda )CDM-like behaviour without vacuum energy. Finally, we propose a general route for extending dynamical systems analysis to broader classes of f(Q) models using the (m_i)-hierarchy method. This framework enables closure for models previously inaccessible to standard approaches and offers a diagnostic tool for identifying structurally viable cosmologies within modified gravity theories.

We investigate the Domain-Wall Standard Model (DWSM), a five-dimensional framework in which all Standard Model (SM) particles are localized on a domain wall embedded in a non-compact extra spatial dimension. A distinctive feature of this setup is the emergence of a Nambu–Goldstone (NG) boson, arising from the spontaneous breaking of translational invariance in the extra dimension due to the localization of SM chiral fermions. This NG boson couples via Yukawa interactions to SM fermions and their Kaluza–Klein (KK) excitations. We study the phenomenology of this NG boson and derive constraints from astrophysical processes (supernova cooling), Big Bang Nucleosynthesis (BBN), and collider searches for KK-mode fermions at the Large Hadron Collider (LHC). The strongest limits arise from LHC data: we reinterpret existing mass bounds on squarks and sleptons in simplified supersymmetric models (assuming a massless lightest neutralino), as well as limits on exotic hadrons containing long-lived squarks or long-lived charged sleptons in the regime of extremely small Yukawa couplings. From this analysis, we obtain a conservative lower bound of 1 TeV on the masses of KK-mode quarks and charged leptons. Finally, we discuss the prospects for producing KK-mode fermions at future high-energy lepton colliders and outline strategies to distinguish their signatures from those of sfermions.

We present a PyTorch-based framework for forward folded reactor neutrino spectrum fitting that accelerates the two main bottlenecks: IBD mapping and detector response, using (i) result caching, (ii) banded sparse matrices, and (iii) blocked construction of the response. On an Intel Xeon Gold 6338 CPU, these techniques reduce per-fit walltime by (approx 7times ) (median over 5 runs) relative to a dense, unoptimized implementation, with (<10^{-6}) relative spectral error versus a double-precision baseline. The framework has been applied to reactor-neutrino oscillation analyses and is reusable in other neutrino experiments that rely on forward-folded energy spectra, enabling practical Feldman–Cousins coverage studies and large parameter scans at substantially lower computational cost.

In this paper, we investigate a digitised SU(2) lattice gauge theory in the Hamiltonian formalism. We use partitionings to digitise the gauge degrees of freedom and show how to define a penalty term based on finite element methods to project onto physical states of the system. Moreover, we show for a single plaquette system that in this framework the limit (grightarrow 0) can be approached at constant cost.

The Regge–Gribov model of the pomeron and odderon in non-trivial transverse space is studied by the renormalization group technique in the single-loop approximation. The pomeron and odderon are taken to have different bare intercepts and slopes. The behaviour when the intercepts move from below to their critical values compatible with the Froissart limitation is studied. The singularities in the form of non-trivial branch points indicating a phase transition are found in the vicinity of five fixed points reported in a previous publication. Since new phases violate the projectile–target symmetry, the model is found non-physical for the bare intercepts above their critical value.