The European Physical Journal C

List of Papers (Total 3,038)

Search for single production of the vector-like top partner at the 14 TeV LHC

The new heavy vector-like top partner (T) is one of typical features of many new physics models beyond the standard model. In this paper we study the discovery potential of the LHC for the vector-like T-quark both in the leptonic $T\rightarrow bW$ and $T\rightarrow t_\mathrm{lep}Z_\mathrm{lep}$ (trilepton) channels at $\sqrt{s}= 14$ TeV in the single production mode. Our ...

Measurement of meson resonance production in $\pi ^-+$ C interactions at SPS energies

We present measurements of $\rho ^0$, $\omega$ and K$^{*0}$ spectra in $\pi ^{-} +$ C production interactions at 158 $\text{ GeV }{/}\text{ c }$ and $\rho ^0$ spectra at 350 $\text{ GeV }{/}\text{ c }$ using the NA61/SHINE spectrometer at the CERN SPS. Spectra are presented as a function of the Feynman’s variable $x_\text {F}$ in the range $0< x_\text {F} < 1$ ...

Branching ratios, CP asymmetries and polarizations of $B\rightarrow \psi (2S) V$ decays

We analyze the non-leptonic decays $B/B_s\rightarrow \psi (2S) V$ with $V=(\rho , \omega , K^{*}, \phi )$ by employing the perturbative QCD (pQCD) factorization approach. Here the branching ratios, the CP asymmetries and the complete set of polarization observables are investigated systematically. Besides the traditional contributions from the factorizable and non-factorizable ...

Unimodular f(G) gravity

In this paper we study a modified version of unimodular general relativity in the context of f(G), G denoting the Gauss–Bonnet invariant. We focus on Bianchi-type I and Friendmann–Robertson–Walker universes and search for unimodular f(G) models according to the de Sitter and power-law solutions. Assuming unimodular f(G) gravity as a perfect fluid and making use of the slow-roll ...

Local conformal symmetry in non-Riemannian geometry and the origin of physical scales

We introduce an extension of the Standard Model and General Relativity built upon the principle of local conformal invariance, which represents a generalization of a previous work by Bars, Steinhardt and Turok. This is naturally realized by adopting as a geometric framework a particular class of non-Riemannian geometries, first studied by Weyl. The gravitational sector is enriched ...

Quantum fluctuations from thermal fluctuations in Jacobson formalism

In the Jacobson formalism general relativity is obtained from thermodynamics. This is done by using the Bekenstein–Hawking entropy–area relation. However, as a black hole gets smaller, its temperature will increase. This will cause the thermal fluctuations to also increase, and these will in turn correct the Bekenstein–Hawking entropy–area relation. Furthermore, with the reduction ...

The effect of the Gauss–Bonnet term on Hawking radiation from arbitrary dimensional black brane

We investigate the probabilities of the tunneling and the radiation spectra of massive spin-1 particles from arbitrary dimensional Gauss–Bonnet–Axions (GBA) Anti-de Sitter (AdS) black branes, via using the WKB approximation to the Proca spin-1 field equation. The tunneling probabilities and Hawking temperature of the arbitrary dimensional GBA AdS black brane is calculated via the ...

Gauges and functional measures in quantum gravity II: higher-derivative gravity

We compute the one-loop divergences in a higher-derivative theory of gravity including Ricci tensor squared and Ricci scalar squared terms, in addition to the Hilbert and cosmological terms, on an (generally off-shell) Einstein background. We work with a two-parameter family of parametrizations of the graviton field, and a two-parameter family of gauges. We find that there are some ...

Non-local deformation of a supersymmetric field theory

In this paper, we will analyze a supersymmetric field theory deformed by generalized uncertainty principle and Lifshitz scaling. It will be observed that this deformed supersymmetric field theory contains non-local fractional derivative terms. In order to construct such a deformed $\mathcal {N} =1$ supersymmetric theory, a harmonic extension of functions will be used. However, ...

Photon and Pomeron-induced Production of Dijets in pp, pA and AA Collisions

In this paper we present a detailed comparison of the dijet production by photon–photon, photon–pomeron and pomeron–pomeron interactions in pp, pA and $\mathrm{AA}$ collisions at the LHC energy. The transverse momentum, pseudo-rapidity and angular dependencies of the cross sections are calculated at LHC energy using the Forward Physics Monte Carlo (FPMC), which allows one to ...

Emergence of running dark energy from polynomial f(R) theory in Palatini formalism

We consider FRW cosmology in $f(R)= R+ \gamma R^2+\delta R^3$ modified framework. The Palatini approach reduces its dynamics to the simple generalization of Friedmann equation. Thus we study the dynamics in two-dimensional phase space with some details. After reformulation of the model in the Einstein frame, it reduces to the FRW cosmological model with a homogeneous scalar field ...

Three-forms in supergravity and flux compactifications

We present a duality procedure that relates conventional four-dimensional matter-coupled $\mathcal{N}=1$ supergravities to dual formulations in which auxiliary fields are replaced by field strengths of gauge three-forms. The duality promotes specific coupling constants appearing in the superpotential to vacuum expectation values of the field strengths. We then apply this general ...

Combining states without scale hierarchies with ordered parton showers

We present a parameter-free scheme to combine fixed-order multi-jet results with parton-shower evolution. The scheme produces jet cross sections with leading-order accuracy in the complete phase space of multiple emissions, resumming large logarithms when appropriate, while not arbitrarily enforcing ordering on momentum configurations beyond the reach of the parton-shower evolution ...

Unified first law and some general prescription: a redefinition of surface gravity

The paper contains an extensive study of the unified first law (UFL) in the Friedmann–Robertson–Walker spacetime model. By projecting the UFL along the Kodama vector the second Friedmann equation can be obtained. Also studying the UFL on the event horizon it is found that the Clausius relation cannot be obtained from the UFL by projecting it along the tangent to the event horizon ...

Triangle singularities in $B^-\rightarrow D^{*0}\pi ^-\pi ^0\eta$ and $B^-\rightarrow D^{*0}\pi ^-\pi ^+\pi ^-$

The possible role of the triangle mechanism in the $B^-$ decay into $D^{*0}\pi ^-\pi ^0\eta$ and $D^{*0}\pi ^-\pi ^+\pi ^-$ is investigated. In this process, the triangle singularity appears from the decay of $B^-$ into $D^{*0}K^-K^{*0}$ followed by the decay of $K^{*0}$ into $\pi ^-K^+$ and the fusion of the $K^+K^-$, which forms the $a_0(980)$ or $f_0(980)$, ...

Lepton identification at particle flow oriented detector for the future $e^{+}e^{-}$ Higgs factories

The lepton identification is essential for the physics programs at high-energy frontier, especially for the precise measurement of the Higgs boson. For this purpose, a toolkit for multivariate data analysis (TMVA) based lepton identification (LICH) has been developed for detectors using high granularity calorimeters. Using the conceptual detector geometry for the Circular ...

Flavor versus mass eigenstates in neutrino asymmetries: implications for cosmology

We show that, if they exist, lepton number asymmetries ($L_\alpha$) of neutrino flavors should be distinguished from the ones ($L_i$) of mass eigenstates, since Big Bang Nucleosynthesis (BBN) bounds on the flavor eigenstates cannot be directly applied to the mass eigenstates. Similarly, Cosmic Microwave Background (CMB) constraints on the mass eigenstates do not directly ...

Mellin–Barnes meets Method of Brackets: a novel approach to Mellin–Barnes representations of Feynman integrals

In this paper, we present a new approach to the construction of Mellin–Barnes representations for Feynman integrals inspired by the Method of Brackets. The novel technique is helpful to lower the dimensionality of Mellin–Barnes representations in complicated cases, some examples are given.

Dissecting multi-photon resonances at the large hadron collider

We examine the phenomenology of the production, at the 13 TeV Large Hadron Collider (LHC), of a heavy resonance X, which decays via other new on-shell particles n into multi-(i.e. three or more) photon final states. In the limit that n has a much smaller mass than X, the multi-photon final state may dominantly appear as a two-photon final state because the $\gamma$s from the n ...

Hidden spin-3/2 field in the standard model

Here we show that a massive spin-3/2 field can hide in the SM spectrum in a way revealing itself only virtually. We study collider signatures and loop effects of this field, and determine its role in Higgs inflation and its potential as dark matter. We show that this spin-3/2 field has a rich linear collider phenomenology and motivates consideration of a neutrino–Higgs collider. We ...

Observability of inert scalars at the LHC

In this work we investigate the observability of inert doublet model scalars at the LHC operating at the center of mass energy of 14 TeV. The signal production process is $pp \rightarrow AH^\pm \rightarrow ZHW^{\pm }H$ leading to two different final states of $\ell ^+\ell ^-Hjj H$ and $\ell ^+\ell ^-H\ell ^\pm \nu H$ based on the hadronic and leptonic decay channels of the W ...

Decoherence and disentanglement of qubits detecting scalar fields in an expanded spacetime

We consider Unruh–Wald qubit detector model adopted for the far future region of an exactly solvable $1+1$ dimensional scalar field theory in a toy model of Robertson–Walker expanding spacetime. It is shown that the expansion of the spacetime in its history enhances the decoherence of the qubit coupled with a scalar field. Moreover, we consider two entangled qubits, each locally ...

A comparative study on generalized model of anisotropic compact star satisfying the Karmarkar condition

A new solution satisfying the Karmarkar condition is presented here. We were first to have discovered a hypergeometric function metric potential representing embedding class I spacetime. This new solution yields finite values of metric potentials, density, pressure, redshift, etc. and hence a non-singular solution. The solution is well behaved with respect to the parameter $n=12$ ...