The European Physical Journal C

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

List of Papers (Total 3,248)

Measurement of the triple-differential dijet cross section in proton-proton collisions at \(\sqrt{s}=8\,\text {TeV} \) and constraints on parton distribution functions

A measurement is presented of the triple-differential dijet cross section at a centre-of-mass energy of 8\(\,\text {TeV}\) using 19.7\(\,\text {fb}^\text {-1}\) of data collected with the CMS detector in proton-proton collisions at the LHC. The cross section is measured as a function of the average transverse momentum, half the rapidity separation, and the boost of the two leading ...

QCD leading order study of the \(J/\psi \) leptoproduction at HERA within the nonrelativistic QCD framework

As indicated in our previous paper (Zhang and Sun in Phys. Rev. D 96:034002, 2017), the existing literature studying the \(J/\psi \) production in deeply inelastic scattering (DIS) in collinear factorisation is on the basis of a formalism that will lead to wrong results when the ranges of the transverse momentum or the rapidity of the \(J/\psi \) in the laboratory frame do not ...

No-go for tree-level R-symmetry breaking

We show that in gauge mediation models with tree-level R-symmetry breaking where supersymmetry and R-symmetries are broken by different fields, the gaugino mass either vanishes at one loop or finds a contribution from loop-level R-symmetry breaking. Thus tree-level R-symmetry breaking for phenomenology is either no-go or redundant in the simplest type of models. Including explicit ...

Analytical study of anisotropic compact star models

A simple classification is given of the anisotropic relativistic star models, resembling the one of charged isotropic solutions. On the ground of this database, and taking into account the conditions for physically realistic star models, a method is proposed for generating all such solutions. It is based on the energy density and the radial pressure as seeding functions. Numerous ...

Stress tensor correlators of \(\hbox {CCFT}_2\) using flat-space holography

We use the correspondence between three-dimensional asymptotically flat spacetimes and two-dimensional contracted conformal field theories (CCFTs) to derive the stress tensor correlators of \(\hbox {CCFT}_2\). On the gravity side we use the metric formulation instead of the Chern–Simons formulation of three-dimensional gravity. This method can also be used for the four-dimensional ...

New non-linear modified massless Klein–Gordon equation

The massless Klein–Gordon equation on arbitrary curved backgrounds allows for solutions which develop “tails” inside the light cone and, therefore, do not strictly follow null geodesics as discovered by DeWitt and Brehme almost 60 years ago. A modification of the massless Klein–Gordon equation is presented, which always exhibits null geodesic propagation of waves on arbitrary ...

Motion of charged particle in Reissner–Nordström spacetime: a Jacobi-metric approach

The present work discusses motion of neutral and charged particles in Reissner–Nordström spacetime. The constant energy paths are derived in a variational principle framework using the Jacobi metric which is parameterized by conserved particle energy. Of particular interest is the case of particle charge and Reissner–Nordström black hole charge being of same sign, since this leads ...

Seeking sterile neutrinos in Finslerian cosmology

For the first time, to search for sterile neutrinos in the framework of Finler geometry, we constrain four cosmological models using the most stringent constraint we can provide so far. We find that the Finslerian massless sterile neutrino model can, respectively, give a better cosmological fit to data and alleviate the current \(H_0\) tension more effectively than the other three ...

In-medium properties of pseudoscalar \(D_s\) and \(B_s\) mesons

We calculate the shift in the masses and decay constants of \(D_s(1968)\) and \(B_s(5370)\) mesons in hot and dense asymmetric strange hadronic matter using QCD sum rules and chiral SU(3) model. In-medium strange quark condensates \(\left\langle \bar{s}s\right\rangle _{\rho _B}\), and gluon condensates \(\left\langle \frac{\alpha _{s}}{\pi } {G^a}_{\mu \nu } {G^a}^{\mu \nu } ...

Combined fit to the \(e^+e^-\rightarrow \pi ^{+}\pi ^{-}J/\psi \) and \(e^+e^-\rightarrow \pi ^{+}\pi ^{-}\psi (3686)\) line shape

We analyze the cross section of \(e^+e^-\rightarrow \pi ^{+}\pi ^{-}J/\psi \) measured by Belle, BABAR and BESIII experiments. The parameters of the two resonances Y(4220) and Y(4360) are consistent with that in \(e^+e^-\rightarrow \pi ^{+}\pi ^{-}\psi (3686)\). A combined fit is performed to the two cross sections assuming the two resonances Y(4220) and Y(4360) have the same ...

Study of open-charm \(0^+\) states in unitarized chiral effective theory with one-loop potentials

Chiral potentials are derived for the interactions between Goldstone bosons and pseudo-scalar charmed mesons up to next-to-next-to-leading order in a covariant chiral effective field theory with explicit vector charmed-meson degrees of freedom. Using the extended-on-mass-shell scheme, we demonstrate that the ultraviolet divergences and the so-called power counting breaking terms ...

Cosmological evolution of the Higgs boson’s vacuum expectation value

We point out that the expansion of the universe leads to a cosmological time evolution of the vacuum expectation of the Higgs boson. Within the standard model of particle physics, the cosmological time evolution of the vacuum expectation of the Higgs leads to a cosmological time evolution of the masses of the fermions and of the electroweak gauge bosons, while the scale of Quantum ...

Distinguishing f(R) theories from general relativity by gravitational lensing effect

The post-Newtonian formulation of a general class of f(R) theories is set up in a third-order approximation. It turns out that the information of a specific form of f(R) gravity is encoded in the Yukawa potential, which is contained in the perturbative expansion of the metric components. Although the Yukawa potential is canceled in the second-order expression of the effective ...

Weak-field limit of Kaluza–Klein models with spherically symmetric static scalar field: observational constraints

In a multidimensional Kaluza–Klein model with Ricci-flat internal space, we study the gravitational field in the weak-field limit. This field is created by two coupled sources. First, this is a point-like massive body which has a dust-like equation of state in the external space and an arbitrary parameter \(\varOmega \) of equation of state in the internal space. The second source ...

Superconducting cosmic strings as sources of cosmological fast radio bursts

In this paper we calculate the radio burst signals from three kinds of structures of superconducting cosmic strings. By taking into account the observational factors including scattering and relativistic effects, we derive the event rate of radio bursts as a function of redshift with the theoretical parameters \(G\mu \) and \({\mathcal {I}}\) of superconducting strings. Our ...

Constraining generalized non-local cosmology from Noether symmetries

We study a generalized non-local theory of gravity which, in specific limits, can become either the curvature non-local or teleparallel non-local theory. Using the Noether symmetry approach, we find that the coupling functions coming from the non-local terms are constrained to be either exponential or linear in form. It is well known that in some non-local theories, a certain kind ...

Kinetic theory of Jean instability in Eddington-inspired Born–Infeld gravity

We analyze the stability of self-gravitating systems which dynamics is investigated using the collisionless Boltzmann equation, and the modified Poisson equation of Eddington-inspired Born–Infield gravity. These equations provide a description of the Jeans paradigm used to determine the critical scale above which such systems collapse. At equilibrium, the systems are described ...

Reheating, thermalization and non-thermal gravitino production in MSSM inflation

In the framework of MSSM inflation, matter and gravitino production are here investigated through the decay of the fields which are coupled to the udd inflaton, a gauge-invariant combination of squarks. After the end of inflation, the flat direction oscillates about the minimum of its potential, losing at each oscillation about 56% of its energy into bursts of gauge/gaugino and ...

What if? Exploring the multiverse through Euclidean wormholes

We present Euclidean wormhole solutions describing possible bridges within the multiverse. The study is carried out in the framework of third quantisation. The matter content is modelled through a scalar field which supports the existence of a whole collection of universes. The instanton solutions describe Euclidean solutions that connect baby universes with asymptotically de ...

Fate of an accretion disc around a black hole when both the viscosity and dark energy is in effect

This paper deals with the viscous accretion flow of a modified Chaplygin gas towards a black hole as the central gravitating object. A modified Chaplygin gas is a particular type of dark energy model which mimics of radiation era to phantom era depending on the different values of its parameters. We compare the dark energy accretion with the flow of adiabatic gas. An accretion disc ...

Higgs–photon resonances

We study models that produce a Higgs boson plus photon (\(h^0\gamma \)) resonance at the LHC. When the resonance is a \(Z'\) boson, decays to \(h^0\gamma \) occur at one loop. If the \(Z'\) boson couples at tree level to quarks, then the \(h^0\gamma \) branching fraction is typically of order \(10^{-5}\) or smaller. Nevertheless, there are models that would allow the observation of ...

Eternal inflation and the quantum birth of cosmic structure

We consider the eternal inflation scenario of the slow-roll/chaotic type with the additional element of an objective collapse of the wave function. The incorporation of this new agent to the traditional inflationary setting might represent a possible solution to the quantum measurement problem during inflation, a subject that has not reached a consensus among the community. ...

Late-time cosmological approach in mimetic f(R, T) gravity

In this paper, we investigate the late-time cosmic acceleration in mimetic f(R, T) gravity with the Lagrange multiplier and potential in a Universe containing, besides radiation and dark energy, a self-interacting (collisional) matter. We obtain through the modified Friedmann equations the main equation that can describe the cosmological evolution. Then, with several models from ...

Revisiting the ADT mass of the five-dimensional rotating black holes with squashed horizons

We evaluate the Abbott–Deser–Tekin (ADT) mass of the five-dimensional rotating black holes with squashed horizons on two different on-shell reference backgrounds, which are the flat background and the boundary matched Kaluza–Klein (KK) monopole. The mass on the former, identified with the one on the background of the asymptotic geometry, differs from the mass on the latter by that ...

SCYNet: testing supersymmetric models at the LHC with neural networks

SCYNet (SUSY Calculating Yield Net) is a tool for testing supersymmetric models against LHC data. It uses neural network regression for a fast evaluation of the profile likelihood ratio. Two neural network approaches have been developed: one network has been trained using the parameters of the 11-dimensional phenomenological Minimal Supersymmetric Standard Model (pMSSM-11) as an ...