The European Physical Journal C

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

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, ...

The \(B-L\) scotogenic models for Dirac neutrino masses

We construct the one-loop and two-loop scotogenic models for Dirac neutrino mass generation in the context of \(U(1)_{B-L}\) extensions of standard model. It is indicated that the total number of intermediate fermion singlets is uniquely fixed by the anomaly free condition and the new particles may have exotic \(B-L\) charges so that the direct SM Yukawa mass term \(\bar{\nu }_L\nu ...

Material radioassay and selection for the XENON1T dark matter experiment

The XENON1T dark matter experiment aims to detect weakly interacting massive particles (WIMPs) through low-energy interactions with xenon atoms. To detect such a rare event necessitates the use of radiopure materials to minimize the number of background events within the expected WIMP signal region. In this paper we report the results of an extensive material radioassay campaign ...

Trilinear Higgs coupling determination via single-Higgs differential measurements at the LHC

We study one-loop effects induced by an anomalous Higgs trilinear coupling on total and differential rates for the \(H\rightarrow 4\ell \) decay and some of the main single-Higgs production channels at the LHC, namely, VBF, VH, \(t{\bar{t}}H\) and tHj. Our results are based on a public code that calculates these effects by simply reweighting samples of Standard-Model-like events ...

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 ...

The generalized cosmic equation of state: a revised study with cosmological standard rulers

In this paper, the generalized equation of state (GEoS) for dark energy (\(w_\beta =w_0-w_{\beta }[(1+z)^{-\beta }-1]/\beta \)) is investigated with the combined standard ruler data from the observations of intermediate-luminosity radio quasars, galaxy clusters, BAO and CMB. The constraint results show that the best-fit EoS parameters are \(w_0=-\,0.94^{+0.57}_{-0.41}\), \(w_\beta ...

High-temperature expansion of the one-loop effective action induced by scalar and Dirac particles

The complete nonperturbative expressions for the high-temperature expansion of the one-loop effective action induced by the charged scalar and the charged Dirac particles both at zero and finite temperatures are derived with account of possible nontrivial boundary conditions. The background electromagnetic field is assumed to be stationary and such that the corresponding ...

Reconstruction from scalar–tensor theory and the inhomogeneous equation of state in f(T) gravity

General relativity (GR) characterizes gravity as a geometric properly exhibited as curvature on spacetime. Teleparallelism describes gravity through torsional properties, and can reproduce GR at the level of equations. Similar to f(R) gravity, on taking a generalization, f(T) gravity can produce various modifications its gravitational mechanism. The resulting field equations are ...

The XENON1T dark matter experiment

The XENON1T experiment at the Laboratori Nazionali del Gran Sasso (LNGS) is the first WIMP dark matter detector operating with a liquid xenon target mass above the ton-scale. Out of its 3.2 t liquid xenon inventory, 2.0 t constitute the active target of the dual-phase time projection chamber. The scintillation and ionization signals from particle interactions are detected with ...

Constraints on inflation revisited: an analysis including the latest local measurement of the Hubble constant

We revisit the constraints on inflation models by using the current cosmological observations involving the latest local measurement of the Hubble constant (\(H_{0} = 73.00\pm 1.75\) km s \(^{-1}\) Mpc\(^{-1}\)). We constrain the primordial power spectra of both scalar and tensor perturbations with the observational data including the Planck 2015 CMB full data, the BICEP2 and Keck ...

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 ...

Magnetic moments of the spin- \({\frac{3}{2}}\) doubly heavy baryons

In this work, we investigate the chiral corrections to the magnetic moments of the spin-\(3\over 2\) doubly charmed baryons systematically up to next-to-next-to-leading order with the heavy baryon chiral perturbation theory. The numerical results are given up to next-to-leading order: \(\mu _{\varXi ^{*++}_{cc}}=2.61\mu _{N}\), \(\mu _{\varXi ^{*+}_{cc}}=-0.18\mu _{N}\), \(\mu ...

Cabibbo–Kobayashi–Maskawa-favored B decays to a scalar meson and a D meson

In this work, we attempt to study the Cabibbo–Kobayashi–Maskawa-favored \(B \rightarrow \overline{D} S\) (“S” denoting the scalar meson) decays within the perturbative QCD approach at the leading order and the leading power. Although the light scalar mesons are widely perceived as primarily the four-quark bound states, in practice it is hard for us to make quantitative predictions ...

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 ...