# The European Physical Journal C

## List of Papers (Total 3,248)

#### Dark matter stability and one-loop neutrino mass generation based on Peccei–Quinn symmetry

We propose a model which is a simple extension of the KSVZ invisible axion model with an inert doublet scalar. Peccei–Quinn symmetry forbids tree-level neutrino mass generation and its remnant $Z_2$ symmetry guarantees dark matter stability. The neutrino masses are generated by one-loop effects as a result of the breaking of Peccei–Quinn symmetry through a nonrenormalizable ...

#### Interaction between two point-like charges in nonlinear electrostatics

We consider two point-like charges in electrostatic interaction within the framework of a nonlinear model, associated with QED, that provides finiteness of their field energy. We find the common field of the two charges in a dipole-like approximation, where the separation between them R is much smaller than the observation distance r : with the linear accuracy with respect to the ...

#### Emergent cosmos in Einstein–Cartan theory

Based on Padmanabhan’s proposal, the accelerated expansion of the universe can be driven by the difference between the surface and bulk degrees of freedom in a region of space, described by the relation $\mathrm{d}V/\mathrm{d}t = N_\mathrm{sur}-N_\mathrm{bulk}$ where $N_\mathrm{sur}$ and $N_\mathrm{bulk}= -N_\mathrm{em} +N_\mathrm{de}$ are the degrees of freedom assigned to ...

#### A new look at the Y tetraquarks and $\Omega _c$ baryons in the diquark model

We analyze the hidden charm P-wave tetraquarks in the diquark model, using an effective Hamiltonian incorporating the dominant spin–spin, spin–orbit and tensor interactions. We compare with other P-wave systems such as P-wave charmonia and the newly discovered $\Omega _c$ baryons, analysed recently in this framework. Given the uncertain experimental situation on the Y states, we ...

#### Anisotropic generalization of well-known solutions describing relativistic self-gravitating fluid systems: an algorithm

We present an algorithm to generalize a plethora of well-known solutions to Einstein field equations describing spherically symmetric relativistic fluid spheres by relaxing the pressure isotropy condition on the system. By suitably fixing the model parameters in our formulation, we generate closed-form solutions which may be treated as an anisotropic generalization of a large class ...

#### Regge-like relation and a universal description of heavy–light systems

Using the Regge-like formula $(M-m_Q)^2=\pi \sigma L$ between hadron mass M and angular momentum L with a heavy quark mass $m_Q$ and a string tension $\sigma$, we analyze all the heavy–light systems, i.e., $D/D_s/B/B_s$ mesons and charmed and bottom baryons. Numerical plots are obtained for all the heavy–light mesons of experimental data whose slope becomes nearly equal to ...

#### SpecBit, DecayBit and PrecisionBit: GAMBIT modules for computing mass spectra, particle decay rates and precision observables

We present the GAMBIT modules SpecBit, DecayBit and PrecisionBit. Together they provide a new framework for linking publicly available spectrum generators, decay codes and other precision observable calculations in a physically and statistically consistent manner. This allows users to automatically run various combinations of existing codes as if they are a single package. The ...

#### Hyperunified field theory and gravitational gauge–geometry duality

A hyperunified field theory is built in detail based on the postulates of gauge invariance and coordinate independence along with the conformal scaling symmetry. All elementary particles are merged into a single hyper-spinor field and all basic forces are unified into a fundamental interaction governed by the hyper-spin gauge symmetry SP(1, $D_h-1$). The dimension $D_h$ of ...

#### Einstein and Rastall theories of gravitation in comparison

We profit by a recent paper of Visser claiming that Rastall gravity is equivalent to Einstein gravity to compare the two gravitational theories in a general way. Our conclusions are different from Visser’s ones. We indeed argue that these two theories are not equivalent. In fact, Rastall theory of gravity is an “open” theory when compared to Einstein general theory of relativity. ...

#### On the emergence of the $\mathbf{\Lambda }$ CDM model from self-interacting Brans–Dicke theory in $\mathbf{d= 5}$

We investigate whether a self-interacting Brans–Dicke theory in $d=5$ without matter and with a time-dependent metric can describe, after dimensional reduction to $d=4$, the FLRW model with accelerated expansion and non-relativistic matter. By rewriting the effective 4-dimensional theory as an autonomous 3-dimensional dynamical system and studying its critical points, we show ...

#### Production of $\tau \tau jj$ final states at the LHC and the TauSpinner algorithm: the spin-2 case

The TauSpinner algorithm is a tool that allows one to modify the physics model of the Monte Carlo generated samples due to the changed assumptions of event production dynamics, but without the need of re-generating events. With the help of weights $\tau$-lepton production or decay processes can be modified accordingly to a new physics model. In a recent paper a new version ...

#### Effects of the fermionic vacuum polarization in QED

Some effects of vacuum polarization in QED due to the presence of field sources are investigated. We focus on effects with no counter-part in Maxwell electrodynamics. The the Uehling interaction energy between two stationary point-like charges is calculated exactly in terms of Meijer-G functions. Effects induced on a hydrogen atom by the vacuum polarization in the vicinity of a ...

#### Temperature quenching in LAB based liquid scintillator

The effect of temperature changes on the light output of LAB based liquid scintillator is investigated in a range from $-5$ to $30\,^{\circ }$C with $\alpha$-particles and electrons in a small scale setup. Two PMTs observe the scintillator liquid inside a cylindrically shaped aluminum cuvette that is heated or cooled and the temperature dependent PMT sensitivity is monitored ...

#### Relativistic dynamics of point magnetic moment

The covariant motion of a classical point particle with magnetic moment in the presence of (external) electromagnetic fields is revisited. We are interested in understanding extensions to the Lorentz force involving point particle magnetic moment (Stern–Gerlach force) and how the spin precession dynamics is modified for consistency. We introduce spin as a classical particle ...

#### Effects of next-to-leading order DGLAP evolution on generalized parton distributions of the proton and deeply virtual Compton scattering at high energy

We studied the effects of NLO $Q^2$ evolution of generalized parton distributions (GPDs) using the aligned-jet model for the singlet quark and gluon GPDs at an initial evolution scale. We found that the skewness ratio for quarks is a slow logarithmic function of $Q^2$, reaching $r^\mathrm{S}=1.5{-}2$ at $Q^2=100$ GeV$^2$ and $r^\mathrm{g} \approx 1$ for gluons in a wide ...

#### Charmonia production from b-hadron decays at LHC with $k_T$ -factorization: $J/\psi$ , $\psi (2S)$ and $J/\psi + Z$

We consider the production of $J/\psi$ and $\psi (2S)$ mesons originating from the decays of b-flavored hadrons at the LHC using the $k_T$-factorization approach. Our analysis covers both inclusive charmonia production and production of $J/\psi$ mesons in association with Z bosons. We apply the transverse momentum dependent (or unintegrated) gluon density in a proton ...

#### Quantum tomography for collider physics: illustrations with lepton-pair production

Quantum tomography is a method to experimentally extract all that is observable about a quantum mechanical system. We introduce quantum tomography to collider physics with the illustration of the angular distribution of lepton pairs. The tomographic method bypasses much of the field-theoretic formalism to concentrate on what can be observed with experimental data. We provide a ...

#### Possibility of hypothetical stable micro black hole production at future 100 TeV collider

We study the phenomenology of TeV-scale black holes predicted in theories with large extra dimensions, under the further assumption that they are absolutely stable. Our goal is to present an exhaustive analysis of safety of the proposed 100 TeV collider, as it was done in the case of the LHC. We consider the theories with different number of extra dimensions and identify those for ...

In this paper, we make a deep analysis for the five typical interacting holographic dark energy models with the interaction terms $Q=3\beta H_{0}\rho _\mathrm{{de}}$, $Q=3\beta H_{0}\rho _\mathrm{{c}}$, $Q=3\beta H_{0}(\rho _\mathrm{{de}}+\rho _\mathrm{c})$, $Q=3\beta H_{0}\sqrt{\rho _\mathrm{{de}}\rho _\mathrm{c}}$, and $Q=3\beta H_{0}\frac{\rho _\mathrm{{de}}\rho ... #### Integrability of the Einstein-nonlinear SU(2) \(\sigma$ -model in a nontrivial topological sector

The integrability of the $\Lambda$-Einstein-nonlinear $SU(2)\,\sigma$-model with nonvanishing cosmological charge is studied. We apply the method of singularity analysis of differential equations and we show that the equations for the gravitational field are integrable. The first few terms of the solution are presented.

#### Central and peripheral interactions of hadrons

Surprisingly enough, the ratio of elastic to inelastic cross sections of proton interactions increases with energy in the interval corresponding to ISR$\rightarrow$LHC (i.e. from 10 to 10$^4$ GeV). That leads to special features of their spatial interaction region at these and higher energies. Within the framework of some phenomenological models, we show how the particular ...

#### Covariant extension of the GPD overlap representation at low Fock states

We present a novel approach to compute generalized parton distributions within the lightfront wave function overlap framework. We show how to systematically extend generalized parton distributions computed within the DGLAP region to the ERBL one, fulfilling at the same time both the polynomiality and positivity conditions. We exemplify our method using pion lightfront wave ...

#### Complexity growth rates for AdS black holes in massive gravity and f(R) gravity

The “complexity = action” duality states that the quantum complexity is equal to the action of the stationary AdS black hole within the Wheeler–DeWitt patch at late time approximation. We compute the action growth rates of the neutral and charged black holes in massive gravity and the neutral, charged and Kerr–Newman black holes in f(R) gravity to test this conjecture. Besides, we ...

#### Steering of Sub-GeV electrons by ultrashort Si and Ge bent crystals

We report the observation of the steering of 855 MeV electrons by bent silicon and germanium crystals at the MAinzer MIkrotron. Crystals with 15 $\upmu$m of length, bent along (111) planes, were exploited to investigate orientational coherent effects. By using a piezo-actuated mechanical holder, which allowed to remotely change the crystal curvature, it was possible to study the ...