# The European Physical Journal C

## List of Papers (Total 3,408)

#### Search for direct top squark pair production in final states with two leptons in $\sqrt{s} = 13$ TeV pp collisions with the ATLAS detector

The results of a search for direct pair production of top squarks in events with two opposite-charge leptons (electrons or muons) are reported, using $36.1~\hbox {fb}^{-1}$ of integrated luminosity from proton–proton collisions at $\sqrt{s}=13$ TeV collected by the ATLAS detector at the Large Hadron Collider. To cover a range of mass differences between the top squark ...

#### Hysteresis in $\eta /s$ for QFTs dual to spherical black holes

We define and compute the (analog) shear viscosity to entropy density ratio $\tilde{\eta }/s$ for the QFTs dual to spherical AdS black holes both in Einstein and Gauss–Bonnet gravity in five spacetime dimensions. Although in this case, owing to the lack of translational symmetry of the background, $\tilde{\eta }$ does not have the usual hydrodynamic meaning, it can be still ...

#### Stationary bound-state massive scalar field configurations supported by spherically symmetric compact reflecting stars

It has recently been demonstrated that asymptotically flat neutral reflecting stars are characterized by an intriguing no-hair property. In particular, it has been proved that these horizonless compact objects cannot support spatially regular static matter configurations made of scalar (spin-0) fields, vector (spin-1) fields and tensor (spin-2) fields. In the present paper we shall ...

#### From sine-Gordon to vacuumless systems in flat and curved spacetimes

In this work we start from the Higgs prototype model to introduce a new model, which makes a smooth transition between systems with well-located minima and systems that support no minima at all. We implement this possibility using the deformation procedure, which allows the obtaining a sine-Gordon-like model, controlled by a real parameter that gives rise to a family of models, ...

#### A study of top-quark mass measurement using the lepton energy distribution at the Large Hadron Collider

We present a feasibility study of top-quark mass measurement using the lepton energy distribution in the top-quark decay $t \rightarrow bW \rightarrow b\ell \nu$ at the LHC. The method used in this study requires only the lepton energy distribution at parton level. The analysis is performed in the lepton + jets final state by using fast simulation data corresponding to an ...

#### Note on Weyl versus conformal invariance in field theory

It was argued recently that conformal invariance in flat spacetime implies Weyl invariance in a general curved background for unitary theories and possible anomalies in the Weyl variation of scalar operators are identified. We argue that generically unitarity alone is not sufficient for a conformal field theory to be Weyl invariant. Furthermore, we show explicitly that when a ...

#### Late-time acceleration with steep exponential potentials

In this letter, we study the cosmological dynamics of steeper potential than exponential. Our analysis shows that a simple extension of an exponential potential allows to capture late-time cosmic acceleration and retain the tracker behavior. We also perform statefinder and Om diagnostics to distinguish dark energy models among themselves and with $\Lambda$CDM. In addition, to ...

#### Thermodynamical stability for a perfect fluid

According to the maximum entropy principle, it has been proved that the gravitational field equations could be derived by the extrema of the total entropy for a perfect fluid, which implies that thermodynamic relations contain information as regards gravity. In this manuscript, we obtain a criterion for the thermodynamical stability of an adiabatic, self-gravitating perfect fluid ...

#### Greybody factor of scalar fields from black strings

The greybody factor of massless, uncharged scalar fields is studied in the background of cylindrically symmetric spacetimes, in the low-energy approximation. We discuss two cases. In the first case we derive analytical expression for the absorption probability when the spacetime is kinetically coupled with the Einstein tensor. In the second case we do the analysis in the absence of ...

#### A global fit of the MSSM with GAMBIT

We study the seven-dimensional Minimal Supersymmetric Standard Model (MSSM7) with the new GAMBIT software framework, with all parameters defined at the weak scale. Our analysis significantly extends previous weak-scale, phenomenological MSSM fits, by adding more and newer experimental analyses, improving the accuracy and detail of theoretical predictions, including dominant ...

#### Neutrino mass, leptogenesis and FIMP dark matter in a $\mathrm{U}(1)_{B-L}$ model

The Standard Model (SM) is inadequate to explain the origin of tiny neutrino masses, the dark matter (DM) relic abundance and the baryon asymmetry of the Universe. In this work, to address all three puzzles, we extend the SM by a local U$(1)_{B-L}$ gauge symmetry, three right-handed (RH) neutrinos for the cancellation of gauge anomalies and two complex scalars having non-zero ...

#### Determination of the strong coupling constant $\alpha _\mathrm {s}$ from transverse energy–energy correlations in multijet events at $\sqrt{s} = 8~\hbox {TeV}$ using the ATLAS detector

Measurements of transverse energy–energy correlations and their associated asymmetries in multi-jet events using the ATLAS detector at the LHC are presented. The data used correspond to $\sqrt{s} = 8~\hbox {TeV}$ proton–proton collisions with an integrated luminosity of 20.2$~\hbox {fb}^{-1}$. The results are presented in bins of the scalar sum of the transverse momenta of the ...

#### Stellar equilibrium configurations of white dwarfs in the f(R, T) gravity

In this work we investigate the equilibrium configurations of white dwarfs in a modified gravity theory, namely, f(R, T) gravity, for which R and T stand for the Ricci scalar and trace of the energy-momentum tensor, respectively. Considering the functional form $f(R,T)=R+2\lambda T$, with $\lambda$ being a constant, we obtain the hydrostatic equilibrium equation for the ...

#### The SME gauge sector with minimum length

We study the gauge sector of the Standard Model Extension (SME) with the Lorentz covariant deformed Heisenberg algebra associated to the minimum length. In order to find and estimate corrections, we clarify whether the violation of Lorentz symmetry and the existence of a minimum length are independent phenomena or are, in some way, related. With this goal, we analyze the dispersion ...

#### Generalization of Einstein’s gravitational field equations

The Riemann tensor is the cornerstone of general relativity, but as is well known it does not appear explicitly in Einstein’s equation of gravitation. This suggests that the latter may not be the most general equation. We propose here for the first time, following a rigorous mathematical treatment based on the variational principle, that there exists a generalized 4-index ...