The European Physical Journal C

http://link.springer.com/journal/10052

List of Papers (Total 2,535)

Scattering of W and Z bosons at high-energy lepton colliders

We present a new study of quasi-elastic W and Z scattering processes in high-energy \(e^+e^-\) collisions, based on and extrapolating the low-energy effective theory which extends the standard model with a \(125\;\text {GeV}\) Higgs boson. We parameterize deviations in the low-energy range in terms of the dimension-eight operators that arise in the effective theory. Smoothly ...

Superfield generating equation of field–antifield formalism as a hyper-gauge theory

Within a superfield approach, we formulate a simple quantum generating equation of the field–antifield formalism. Then we derive the Schroedinger equation with the Hamiltonian whose \(\Delta \)-exact part serves as a generator to the quantum master transformations. We show that these generators do satisfy a nice composition law in terms of the quantum antibrackets. We also present ...

Q-balls in the Wick–Cutkosky model

In the present paper Q-ball solutions in the Wick–Cutkosky model are examined in detail. A remarkable feature of the Wick–Cutkosky model is that it admits analytical treatment for the most part of the analysis of Q-balls, which allows one to use this simple model to demonstrate some peculiar properties of Q-balls. In particular, a method for estimating the binding energy of a ...

Generalized polarizabilities of the nucleon in baryon chiral perturbation theory

The nucleon generalized polarizabilities (GPs), probed in virtual Compton scattering (VCS), describe the spatial distribution of the polarization density in a nucleon. They are accessed experimentally via the process of electron–proton bremsstrahlung (\(ep\rightarrow ep\gamma \)) at electron-beam facilities, such as MIT-Bates, CEBAF (Jefferson Lab), and MAMI (Mainz). We present the ...

Influence of incoherent scattering on stochastic deflection of high-energy negative particle beams in bent crystals

An investigation on stochastic deflection of high-energy negatively charged particles in a bent crystal was carried out. On the basis of analytical calculation and numerical simulation it was shown that there is a maximum angle at which most of the beam is deflected. The existence of a maximum, which is taken in the correspondence of the optimal radius of curvature, is a novelty ...

Review of lattice results concerning low-energy particle physics

We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle-physics community. More specifically, we report on the determination of the light-quark masses, the form factor \(f_+(0)\), arising in the semileptonic \(K \rightarrow \pi \) transition at zero momentum transfer, as well as the decay constant ratio ...

Cracking of charged polytropes with generalized polytropic equation of state

We discuss the occurrence of cracking in charged anisotropic polytropes with generalized polytropic equation of state through two different assumptions; (i) by carrying out local density perturbations under a conformally flat condition (ii) by perturbing anisotropy, polytropic index and charge parameters. For this purpose, we consider two different definitions of polytropes that ...

Total pion–proton cross section from the new LHCf data on leading neutrons spectra

In the light of the latest data by the LHCf collaboration of the LHC on leading neutrons spectra it is possible to obtain total pion–proton cross sections in the TeV energy region. In this work the exact extraction procedure is shown. Final results for the pion–proton cross section are collected at several different values of the colliding energy and compared with some popular ...

Full linear perturbations and localization of gravity on f(R, T) brane

We study the thick brane world system constructed in the recently proposed f(R, T) theories of gravity, with R the Ricci scalar and T the trace of the energy-momentum tensor. We try to get the analytic background solutions and discuss the full linear perturbations, especially the scalar perturbations. We compare how the brane world model is modified with that of general relativity ...

Study the effect of beam energy spread and detector resolution on the search for Higgs boson decays to invisible particles at a future e \(^+\) e \(^-\) circular collider

We study the expected sensitivity to measure the branching ratio of Higgs boson decays to invisible particles at a future circular \(e^+e^-\)collider (FCC-ee) in the process \(e^+e^-\rightarrow HZ\) with \(Z\rightarrow \ell ^+\ell ^-\) (\(\ell =e\) or \(\mu \)) using an integrated luminosity of 3.5 ab\(^{-1}\) at a center-of-mass energy \(\sqrt{s}=240\) GeV. The impact of the ...

A comparative study between EGB gravity and GTR by modeling compact stars

In this paper we utilise the Krori–Barua ansatz to model compact stars within the framework of Einstein–Gauss–Bonnet (EGB) gravity. The thrust of our investigation is to carry out a comparative analysis of the physical properties of our models in EGB and classical general relativity theory with the help of graphical representation. From our analysis we have shown that the central ...

Noether symmetry approach in f(T, B) teleparallel cosmology

We consider the cosmology derived from f(T, B) gravity where T is the torsion scalar and \(B=\frac{2}{e}\partial _{\mu }(e T^{\mu })\) a boundary term. In particular we discuss how it is possible to recover, under the same standard, the teleparallel f(T) gravity, the curvature f(R) gravity, and the teleparallel–curvature f(R, T) gravity, which are particular cases of f(T, B). We ...

Tree-level equivalence between a Lorentz-violating extension of QED and its dual model in electron–electron scattering

S-matrix amplitudes for the electron–electron scattering are calculated in order to verify the physical equivalence between two Lorentz-breaking dual models. We begin with an extended Quantum Electrodynamics which incorporates CPT-even Lorentz-violating kinetic and mass terms. Then, in a process of gauge embedding, its gauge-invariant dual model is obtained. The physical ...

Inflation and acceleration of the universe by nonlinear magnetic monopole fields

Despite impressive phenomenological success, cosmological models are incomplete without an understanding of what happened at the big bang singularity. Maxwell electrodynamics, considered as a source of the classical Einstein field equations, leads to the singular isotropic Friedmann solutions. In the context of Friedmann–Robertson–Walker (FRW) spacetime, we show that singular ...

On corpuscular theory of inflation

In order to go beyond the mean-field approximation, commonly used in the inflationary computations, an identification of the quantum constituents of the inflationary background is made. In particular, the homogeneous scalar field configuration is represented as a Bose–Einstein condensate of the off-shell inflaton degrees of freedom, with mass significantly screened by the ...

W production at LHC: lepton angular distributions and reference frames for probing hard QCD

Precision tests of the Standard Model in the Strong and Electroweak sectors play a crucial role, among the physics program of LHC experiments. Because of the nature of proton–proton processes, observables based on the measurement of the direction and energy of final state leptons provide the most precise probes of such processes. In the present paper, we concentrate on the angular ...

Thermodynamic geometry and phase transitions of dyonic charged AdS black holes

We investigate phase transitions and critical phenomena of four dimensional dyonic charged AdS black holes in the framework of thermodynamic geometry. In a mixed canonical–grand canonical ensemble with a fixed electric charge and varying magnetic charge these black holes exhibit a liquid–gas like first order phase transition culminating in a second order critical point similar to ...

Likelihood analysis of supersymmetric SU(5) GUTs

We perform a likelihood analysis of the constraints from accelerator experiments and astrophysical observations on supersymmetric (SUSY) models with SU(5) boundary conditions on soft SUSY-breaking parameters at the GUT scale. The parameter space of the models studied has seven parameters: a universal gaugino mass \(m_{1/2}\), distinct masses for the scalar partners of matter ...

Radiative neutrino mass in alternative left–right model

We propose a radiative seesaw model in an alternative left–right model without any bidoublet scalar fields, in which all the fermion masses in the standard model are generated through a canonical seesaw mechanism at the tree level. On the other hand the observed neutrino masses are generated at two-loop level. In this paper we focus on the neutrino sector and show how to induce the ...

Radiation fluid stars in the non-minimally coupled \(Y(R)F^2\) gravity

We propose a non-minimally coupled gravity model in \( Y(R)F^2 \) form to describe the radiation fluid stars which have the radiative equation of state between the energy density \(\rho \) and the pressure p given by \(\rho =3p.\) Here \(F^2\) is the Maxwell invariant and Y(R) is a function of the Ricci scalar R. We give the gravitational and electromagnetic field equations in ...

A study of the \(\gamma ^*\) – \(f_{0}(980)\) transition form factors

The \(\gamma ^*\)–\(f_{0}(980)\) transition form factors are calculated within the QCD factorization framework. The \(f_0\)-meson is assumed to be mainly generated through its \(s\bar{s}\) Fock component. The corresponding spin wave function of the \(f_{0}(980)\) meson is constructed and, combined with a model light-cone wave function for this Fock component, used in the ...

The lower bound violation of shear viscosity to entropy ratio due to logarithmic correction in STU model

In this paper, we analyze the effects of thermal fluctuations on a STU black hole. We observe that these thermal fluctuations can affect the stability of a STU black hole. We will also analyze the effects of these thermal fluctuations on the thermodynamics of a STU black hole. Furthermore, in the Jacobson formalism such a modification will produce a deformation of the geometry of ...

Vacuum polarization and classical self-action near higher-dimensional defects

We analyze the gravity-induced effects associated with a massless scalar field in a higher-dimensional spacetime being the tensor product of \((d-n)\)-dimensional Minkowski space and n-dimensional spherically/cylindrically symmetric space with a solid/planar angle deficit. These spacetimes are considered as simple models for a multidimensional global monopole (if \(n\geqslant 3\)) ...

The one-loop contributions to c(t) electric dipole moment in the CP-violating BLMSSM

In the CP-violating supersymmetric extension of the standard model with local gauged baryon and lepton symmetries (BLMSSM), there are new CP-violating sources which can give new contributions to the quark electric dipole moment (EDM). Considering the CP-violating phases, we analyze the EDMs of the quarks c and t. We take into account the contributions from the one-loop diagrams. ...

Physical viability of fluid spheres satisfying the Karmarkar condition

We obtain a new static model of the TOV equation for an anisotropic fluid distribution by imposing the Karmarkar condition. In order to close the system of equations we postulate an interesting form for the \(g_{rr}\) gravitational potential, which allows us to solve for \(g_{tt}\) metric component via the Karmarkar condition. We demonstrate that the new interior solution has ...