The European Physical Journal C

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

List of Papers (Total 3,408)

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 ...

Unitary 4-point correlators from classical geometries

We compute correlators of two heavy and two light operators in the strong coupling and large c limit of the D1D5 CFT which is dual to weakly coupled \(\hbox {AdS}_3\) gravity. The light operators have dimension two and are scalar descendants of the chiral primaries considered in arXiv:​1705.​09250, while the heavy operators belong to an ensemble of Ramond–Ramond ground states. We ...

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 ...

CP violation in leptonic rare \(B^0_s\) decays as a probe of new physics

The decay \(B^0_s\rightarrow \mu ^+\mu ^-\) is a key probe for the search of physics beyond the Standard Model. While the current measurements of the corresponding branching ratio agree with the Standard Model within the uncertainties, significant New-Physics effects may still be hiding in \(B^0_s\rightarrow \mu ^+\mu ^-\). In order to reveal them, the observable \(\mathcal ...

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 corrections to the gravitational backreaction

Effective field theory techniques are used to study the leading order quantum corrections to the gravitational wave backreaction. The effective stress-energy tensor is calculated and it is shown that it has a non-vanishing trace that contributes to the cosmological constant. By comparing the result obtained with LIGO’s data, the first bound on the amplitude of the massive mode is ...

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 ...

Status and prospects of light bino–higgsino dark matter in natural SUSY

Given the recent progress in dark matter direction detection experiments, we examine a light bino–higgsino dark matter (DM) scenario (\(M_1<100\) GeV and \(\mu <300\) GeV) in natural supersymmetry with the electroweak fine tuning measure \(\Delta _\mathrm{EW}<30\). By imposing various constraints, we note that: (i) For \(\mathrm{sign}(\mu /M_1)=+1\), the parameter space allowed by ...

Averages of b-hadron, c-hadron, and \(\tau \) -lepton properties as of summer 2016

This article reports world averages of measurements of b-hadron, c-hadron, and \(\tau \)-lepton properties obtained by the Heavy Flavor Averaging Group using results available through summer 2016. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include ...

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 ...

Reexploration of interacting holographic dark energy model: cases of interaction term excluding the Hubble parameter

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.

All-sky search for high-energy neutrinos from gravitational wave event GW170104 with the Antares neutrino telescope

Advanced LIGO detected a significant gravitational wave signal (GW170104) originating from the coalescence of two black holes during the second observation run on January 4th, 2017. An all-sky high-energy neutrino follow-up search has been made using data from the Antares neutrino telescope, including both upgoing and downgoing events in two separate analyses. No neutrino ...

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 ...

DEPFET detectors for direct detection of MeV Dark Matter particles

The existence of dark matter is undisputed, while the nature of it is still unknown. Explaining dark matter with the existence of a new unobserved particle is among the most promising possible solutions. Recently dark matter candidates in the MeV mass region received more and more interest. In comparison to the mass region between a few GeV to several TeV, this region is ...

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 ...

Lorentz-violating Yang–Mills theory: discussing the Chern–Simons-like term generation

We analyze the Chern–Simons-like term generation in the CPT-odd Lorentz-violating Yang–Mills theory interacting with fermions. Moreover, we study the anomalies of this model as well as its quantum stability. The whole analysis is performed within the algebraic renormalization theory, which is independent of the renormalization scheme. In addition, all results are valid to all ...

Quantum mechanical look at the radioactive-like decay of metastable dark energy

We derive the Shafieloo, Hazra, Sahni and Starobinsky (SHSS) phenomenological formula for the radioactive-like decay of metastable dark energy directly from the principles of quantum mechanics. To this aim we use the Fock–Krylov theory of quantum unstable states. We obtain deeper insight on the decay process as having three basic phases: the phase of radioactive decay, the next ...

Probing new intra-atomic force with isotope shifts

In the development of atomic clocks, some atomic transition frequencies are measured with remarkable precision. These measured spectra may include the effects of a new force mediated by a weakly interacting boson. Such effects might be distilled out from possible violation of a linear relation in isotope shifts between two transitions, as known as King’s linearity, with relatively ...

Photon motion in Kerr–de Sitter spacetimes

We study the general motion of photons in the Kerr–de Sitter black-hole and naked singularity spacetimes. The motion is governed by the impact parameters X, related to the axial symmetry of the spacetime, and q, related to its hidden symmetry. Appropriate ‘effective potentials’ governing the latitudinal and radial motion are introduced and their behavior is examined by the ‘Chinese ...