# The European Physical Journal C

## List of Papers (Total 3,408)

#### Improving the simulation of quark and gluon jets with Herwig 7

The properties of quark and gluon jets, and the differences between them, are increasingly important at the LHC. However, Monte Carlo event generators are normally tuned to data from $e^+e^-$ collisions which are primarily sensitive to quark-initiated jets. In order to improve the description of gluon jets we make improvements to the perturbative and the non-perturbative ...

#### Elastic amplitudes studied with the LHC measurements at 7 and 8 TeV

Recent measurements of the differential cross sections in the forward region of pp elastic scattering at 7 and 8 TeV show the precise form of the t dependence. We present a detailed analysis of these measurements including the structures of the real and imaginary parts of the scattering amplitude. A good description is achieved, confirming in all experiments the existence of a zero ...

#### Getting the most neutrinos out of IsoDAR

Several experimental collaborations worldwide intend to test sterile neutrino models by measuring the disappearance of antineutrinos produced via isotope decay at rest (IsoDAR). The most advanced of these proposals have very similar setups, in which a proton beam strikes a target yielding neutrons which are absorbed by a high isotopic purity ${}^7\hbox {Li}$ converter, yielding ...

#### Is exponential gravity a viable description for the whole cosmological history?

Here we analyse a particular type of F(R) gravity, the so-called exponential gravity which includes an exponential function of the Ricci scalar in the action. Such a term represents a correction to the usual Hilbert–Einstein action. By using Supernovae Ia, Barionic Acoustic Oscillations, Cosmic Microwave Background and H(z) data, the free parameters of the model are well ...

#### Tetraquark and two-meson states at large $N_{\mathrm {c}}$

Considering four-point correlation functions of color-singlet quark bilinears, we investigate, in the large-$N_{\mathrm {c}}$ limit of QCD, the subleading diagrams that involve, in the s-channel of meson–meson scattering amplitudes, two-quark–two-antiquark intermediate states. The latter contribute, together with gluon exchanges, to the formation, at the hadronic level, of ...

#### The signal of ill-defined CPT weakening entanglement in the ${B_d}$ system

In the presence of quantum-gravity fluctuations (space-time foam), the CPT operator may be ill-defined. Its perturbative treatment leads to a modification of the Einstein–Podolsky–Rosen correlation of the neutral meson system by adding an entanglement-weakening term of the wrong exchange symmetry, the $\omega$-effect. In the current paper we identify how to probe the complex ...

#### A systematic study of mass spectra and strong decay of strange mesons

The mass spectrum of the kaon family is analyzed by the modified Godfrey–Isgur model with a color screening effect approximating the kaon as a heavy–light meson system. This analysis gives us the structure and possible assignments of the observed kaon candidates, which can be tested by comparing the theoretical results of their two-body strong decays with the experimental data. ...

#### Chiral perturbation theory for neutron–antineutron oscillations

We construct the Chiral Perturbation Theory operators for neutron–antineutron oscillations and use these to estimate chiral and finite volume corrections at one-loop order.

#### An indirect probe of the higgsino world at the CEPC

The higgsino world is one of the popular natural SUSY scenarios, in which $|\mu | \ll M_{\mathrm{gauginos}} \ll M_{\mathrm{scalars}}$. As such, searching for light degenerate higgsinos becomes an essential task of testing naturalness in supersymmetry (SUSY). In this work, we study the indirect effects of light higgsinos in the process $e^+e^- \rightarrow W^+W^-$ at future Higgs ...

#### Matter–antimatter asymmetry induced by a running vacuum coupling

We show that a CP-violating interaction induced by a derivative coupling between the running vacuum and a non-conserving baryon current may dynamically break CPT and trigger baryogenesis through an effective chemical potential. By assuming a non-singular class of running vacuum cosmologies which provides a complete cosmic history (from an early inflationary de Sitter stage to the ...

#### $J/\psi$ production in polarized and unpolarized ep collision and Sivers and $\cos 2\phi$ asymmetries

We calculate the Sivers and $\cos 2\phi$ azimuthal asymmetries in $J/\psi$ production in the polarized and unpolarized semi-inclusive ep collision, respectively, using the formalism based on the transverse momentum-dependent parton distributions (TMDs). The non-relativistic QCD-based color octet model is employed in calculating the $J/\psi$ production rate. The Sivers ...

#### Einstein–Yang–Mills–Lorentz black holes

Different black hole solutions of the coupled Einstein–Yang–Mills equations have been well known for a long time. They have attracted much attention from mathematicians and physicists since their discovery. In this work, we analyze black holes associated with the gauge Lorentz group. In particular, we study solutions which identify the gauge connection with the spin connection. ...

#### Possible signature of the magnetic fields related to quasi-periodic oscillations observed in microquasars

The study of quasi-periodic oscillations (QPOs) of X-ray flux observed in the stellar-mass black hole binaries can provide a powerful tool for testing of the phenomena occurring in the strong gravity regime. Magnetized versions of the standard geodesic models of QPOs can explain the observationally fixed data from the three microquasars. We perform a successful fitting of the HF ...

#### A $1+5$ -dimensional gravitational-wave solution: curvature singularity and spacetime singularity

We solve a $1+5$-dimensional cylindrical gravitational-wave solution of the Einstein equation, in which there are two curvature singularities. Then we show that one of the curvature singularities can be removed by an extension of the spacetime. The result exemplifies that the curvature singularity is not always a spacetime singularity; in other words, the curvature singularity ...

#### Low energy analysis techniques for CUORE

CUORE is a tonne-scale cryogenic detector operating at the Laboratori Nazionali del Gran Sasso (LNGS) that uses tellurium dioxide bolometers to search for neutrinoless double-beta decay of $^{130}$Te. CUORE is also suitable to search for low energy rare events such as solar axions or WIMP scattering, thanks to its ultra-low background and large target mass. However, to conduct ...

#### R-parity violation at the LHC

We investigate the phenomenology of the MSSM extended by a single R-parity-violating coupling at the unification scale. For all R-parity-violating couplings, we discuss the evolution of the particle spectra through the renormalization group equations and the nature of the lightest supersymmetric particle (LSP) within the CMSSM, as an example of a specific complete supersymmetric ...

#### Two-photon exchange correction to the hyperfine splitting in muonic hydrogen

We reevaluate the Zemach, recoil and polarizability corrections to the hyperfine splitting in muonic hydrogen expressing them through the low-energy proton structure constants and obtain the precise values of the Zemach radius and two-photon exchange (TPE) contribution. The uncertainty of TPE correction to S energy levels in muonic hydrogen of 105 ppm exceeds the ppm accuracy level ...

#### The anomalous $U(1)_{\mathrm{anom}}$ symmetry and flavors from an SU(5) $\times$ SU(5) $'$ GUT in $\mathbf{Z}_{12-I}$ orbifold compactification

In string compactifications, frequently the anomalous U(1) gauge symmetry appears which belongs to $E_8 \times E_8'$ of the heterotic string. This anomalous U(1) gauge boson obtains mass at the compactification scale ($\approx 10^{18\,}\,\text {GeV}$) by absorbing one pseudoscalar (corresponding to the model-independent axion) from the second rank antisymmetric tensor field ...

#### A nearly cylindrically symmetric source in Brans–Dicke gravity as the generator of the rotational curves of the galaxies

Observation shows that the velocities of stars grow by approximately 2–3 orders of magnitude when the distances from the centers of the galaxies are in the range of 0.5–82.3 kpc, before they begin to tend to a constant value. Up to now, the reason for this behavior is still a matter for debate. In this work, we propose a model which adequately describes this unusual behavior using ...

#### Black string in dRGT massive gravity

We present a cylindrically symmetric solution, both charged and uncharged, which is known as a black string solution to the nonlinear ghost-free massive gravity found by de Rham, Gabadadze, and Tolley (dRGT). This “dRGT black string” can be thought of as a generalization of the black string solution found by Lemos. Moreover, the dRGT black string solution includes other classes of ...

#### Bulk viscous matter and recent acceleration of the universe based on causal viscous theory

The evolution of the bulk viscous matter dominated universe has been analysed using the full causal theory for the evolution of the viscous pressure in the context of the recent acceleration of the universe. The form of the viscosity is taken as $\xi =\alpha \rho ^{1/2}.$ We obtained analytical solutions for the Hubble parameter and scale factor of the universe. The model ...

#### Effective potential in Lorentz-breaking field theory models

We calculate explicitly the one-loop effective potential in different Lorentz-breaking field theory models. First, we consider a Yukawa-like theory and some examples of Lorentz-violating extensions of scalar QED. We observe, for the extended QED models, that the resulting effective potential converges to the known result in the limit in which Lorentz symmetry is restored. Besides, ...

#### Heavy neutrino mixing in the T2HK, the T2HKK and an extension of the T2HK with a detector at Oki Islands

We study the discovery potential for the mixing of heavy isospin-singlet neutrinos in extensions of the Tokai-to-Kamioka (T2K) experiment, the Tokai-to-Hyper-Kamiokande (T2HK), the Tokai-to-Hyper-Kamiokande-to-Korea (T2HKK) with a Korea detector with $\simeq 1000$ km baseline length and $1^\circ$ off-axis angle, and a plan of adding a small detector at Oki Islands to the T2HK. ...

#### Fermion localization in higher curvature and scalar–tensor theories of gravity

It is well known that, in a braneworld model, the localization of fermions on a lower dimensional submanifold (say a TeV 3-brane) is governed by the gravity in the bulk, which also determines the corresponding phenomenology on the brane. Here we consider a five dimensional warped spacetime where the bulk geometry is governed by higher curvature like F(R) gravity. In such a ...