# The European Physical Journal C

## List of Papers (Total 3,619)

#### The method of generating functions in exact scalar field inflationary cosmology

The construction of exact solutions in scalar field inflationary cosmology is of growing interest. In this work, we review the results which have been obtained with the help of one of the most effective methods, viz., the method of generating functions for the construction of exact solutions in scalar field cosmology. We also include in the debate the superpotential method, which...

#### Collapsing spherical star in Scalar-Einstein-Gauss-Bonnet gravity with a quadratic coupling

We study the evolution of a self interacting scalar field in Einstein-Gauss-Bonnet theory in four dimension where the scalar field couples non minimally with the Gauss-Bonnet term. Considering a polynomial coupling of the scalar field with the Gauss-Bonnet term, a self-interaction potential and an additional perfect fluid distribution alongwith the scalar field, we investigate...

#### Is pulsar timing a hopeful tool for detection of relic gravitational waves by using GW150914 data?

The inflation stage has a behaviour as power law expansion like $S(\eta )\propto \eta ^{1+\beta }$ where $\beta$ constrained on the $1+\beta <0$. If the inflation were preceded by a radiation era, then there would be thermal spectrum of relic gravitational waves at the time of inflation. Based on this idea we find new upper bound on $\beta$ by comparison the thermal...

#### Search for heavy ZZ resonances in the $$\ell ^+\ell ^-\ell ^+\ell ^-$$ and $$\ell ^+\ell ^-\nu \bar{\nu }$$ℓ+ℓ-νν¯ final states using proton–proton collisions at $$\sqrt{s}= 13$$s=13 $$\text {TeV}$$TeV with the ATLAS detector

A search for heavy resonances decaying into a pair of $Z$ bosons leading to $\ell ^+\ell ^-\ell ^+\ell ^-$ and $\ell ^+\ell ^-\nu \bar{\nu }$ final states, where $\ell$ stands for either an electron or a muon, is presented. The search uses proton–proton collision data at a centre-of-mass energy of 13 $\text {TeV}$ corresponding to an integrated luminosity of 36.1...

#### Transport phenomena and Weyl correction in effective holographic theory of momentum dissipation

We construct a higher derivative theory involving an axionic field and the Weyl tensor in four dimensional spacetime. Up to the first order of the coupling parameters, the charged black brane solution with momentum dissipation in a perturbative manner is constructed. Metal–insulator transitions are implemented when varying the system parameters at zero temperature. Also, we study...

#### Search for new phyic in event with a leptonically decaying Z boon and a large tranvere momentum imbalance in proton–proton colliion at $$\qrt{}$$ = 13$$\,\text {TeV}$$TeV

A search for new physics in events with a Z boson produced in association with large missing transverse momentum at the LHC is presented. The search is based on the 2016 data sample of proton-proton collisions recorded with the CMS experiment at $\sqrt{s} = 13\,\text {TeV}$, corresponding to an integrated luminosity of 35.9$\,\text {fb}^{-1}$. The results of this search are...

#### The Constrained NMSSM with right-handed neutrinos

In this article, we demonstrate that the inclusion of right-handed neutrino superfields in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) makes it possible to impose universality conditions on the soft supersymmetry-breaking parameters at the Grand Unification scale, alleviating many of the problems of the so-called Constrained NMSSM. We have studied the...

#### Measurement of associated Z + charm production in proton–proton collisions at $$\sqrt{s} = 8$$$$\,\text {TeV}$$TeV

A study of the associated production of a $\mathrm{Z}$ boson and a charm quark jet ($\mathrm{Z} + \mathrm{c}$), and a comparison to production with a $\mathrm{b}$ quark jet ($\mathrm{Z} + \mathrm{b}$), in $\mathrm {p}\mathrm {p}$ collisions at a centre-of-mass energy of 8$\,\text {TeV}$ are presented. The analysis uses a data sample corresponding to an integrated...

#### $$\mu -\tau$$ reflection symmetry embedded in minimal seesaw

We embed $\mu -\tau$ reflection symmetry into the minimal seesaw formalism, where two right-handed neutrinos are added to the Standard Model of particle physics. Assuming that both the left- and right-handed neutrino fields transform under $\mu -\tau$ reflection symmetry, we obtain the required forms of the neutrino Dirac mass matrix and the Majorana mass matrix for the...

#### Thermal model descri ption of p– Pb collisions at $$\sqrt{s_{NN}} = 5.02$$ TeV

The ALICE data on light flavor hadron production obtained in p–Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV are studied in the thermal model using the canonical approach with exact strangeness conservation. The chemical freeze-out temperature is independent of centrality except for the lowest multiplicity bin, with values close to 160 MeV but consistent with those obtained in Pb...

#### Some families of relativistic anisotropic compact stellar models embedded in pseudo-Euclidean space $$E^5$$: an algorithm

This work presents an algorithm for modeling a static spherically symmetric compact object satisfying the Eiesland condition (Eiesland in Am Math Soc 27:213, 1925), a necessary and sufficient condition that a general centro-symmetric space shall be of the class 1. The model parameters are obtained accordingly by employing the boundary conditions to the interior solutions. The...

#### Quasinormal frequencies of gravitational perturbation in regular black hole spacetimes

The quasinormal frequencies of gravitational perturbation around some well-known regular black holes were investigated in this work. We consider complete perturbations of the energy-momentum tensor of electromagnetic part for non-linear electrodynamics and gravitational field. By using the WKB approximation and the asymptotic iteration method, we make a detailed analysis of the...

#### An inverse mass expansion for entanglement entropy in free massive scalar field theory

We extend the entanglement entropy calculation performed in the seminal paper by Srednicki (Phys Rev Lett 71:666, 1993) for free real massive scalar field theories in $1+1$, $2+1$ and $3+1$ dimensions. We show that the inverse of the scalar field mass can be used as an expansion parameter for a perturbative calculation of the entanglement entropy. We perform the calculation...

#### Spinning pulsating strings in $$(AdS_5 \times S^5)_{\varkappa }$$

We study a general class of spinning pulsating strings in $(AdS_5 \times S^5)_{\varkappa }$ background. For these family of solitons, we examine the scaling relation between the energy, spin or angular momentum. We verify that in $\varkappa \rightarrow 0$ limit these relations reduce to the undeformed $AdS_5 \times S^5$ case. We further study an example of a string which...

#### The stepwise path integral of the relativistic point particle

In this paper we present a stepwise construction of the path integral over relativistic orbits in Euclidean spacetime. It is shown that the apparent problems of this path integral, like the breakdown of the naive Chapman–Kolmogorov relation, can be solved by a careful analysis of the overcounting associated with local and global symmetries. Based on this, the direct calculation...

#### Probing the unitarity of the renormalizable theory of massive conformal gravity

The presence of an unstable massive spin-2 ghost state in the renormalizable theory of massive conformal gravity leads to a pair of complex poles appearing in the first sheet of the energy plane. Here we show that the positions of these poles are gauge dependent, which makes the theory unitary.

#### The $$Z_c(3900)$$ peak does not come from the “triangle singularity”

We compare contributions from the triangle diagram and the $D\bar{D}^*$ bubble chain with the processes of $e^{+}e^{-}\rightarrow J/\psi \pi ^{+}\pi ^{-}$ and $e^{+}e^{-}\rightarrow (D\bar{D}^*)^\mp \pi ^{\pm }$. By fitting the $J/\psi \pi$ maximum spectrum and the $D\bar{D}^*$ spectrum, we find that the triangle diagram cannot explain the new experimental results from...

#### Footprints of leptoquarks: from $$R_{K^{(*)}}$$ to $$K \rightarrow \pi \nu \bar{\nu }$$K→πνν¯

Rare $K \rightarrow \pi \nu \bar{\nu }$ decays, being dominated by short distance contributions within the standard model (SM), open a window for new physics (NP) searches at low energies. The $K \rightarrow \pi \nu \bar{\nu }$ branching ratios are expected to be measured with $\sim 10\%$ accuracies by NA62/CERN and KOTO/JPARC. The theoretical uncertainties of branching...

#### Logarithmic correction to BMSFT entanglement entropy

Using Rindler method we derive the logarithmic correction to the entanglement entropy of a two dimensional BMS-invariant field theory (BMSFT). In particular, we present a general formula for extraction of the logarithmic corrections to both the thermal and the entanglement entropies. We also present a CFT formula related to the logarithmic correction of the BTZ inner horizon...

#### A multi-isotope $$0\nu 2\beta$$ bolometric experiment

There are valuable arguments to perform neutrinoless double beta ($0\nu 2\beta$) decay experiments with several nuclei: the uncertainty of nuclear-matrix-element calculations; the possibility to test these calculations by using the ratio of the measured lifetimes; the unpredictability of possible breakthroughs in the detection technique; the difficulty to foresee background in...