The European Physical Journal C

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

List of Papers (Total 3,050)

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 \(n=12\) ...

Study of color-octet matrix elements through \(J/\psi \) production in \(e^{+}e^{-}\) annihilation

In this paper, the color-octet long distance matrix elements are studied through the inclusive \(J/\psi \) production in \(e^{+}e^{-}\) annihilation within the framework of non-relativistic QCD factorization. The calculations are up-to next-to-leading order with the radiative and relativistic corrections in the energy region of the B-factory and the near-threshold region of ...

Ratios of strange hadrons to pions in collisions of large and small nuclei

The dependence of particle production on the size of the colliding nuclei is analyzed in terms of the thermal model using the canonical ensemble. The concept of strangeness correlation in clusters of sub-volume \(V_c\) is used to account for the suppression of strangeness. A systematic analysis is presented of the predictions of the thermal model for particle production in ...

Controlled flavour changing neutral couplings in two Higgs Doublet models

We propose a class of two Higgs doublet models where there are flavour changing neutral currents (FCNC) at tree level, but under control due to the introduction of a discrete symmetry in the full Lagrangian. It is shown that in this class of models, one can have simultaneously FCNC in the up and down sectors, in contrast to the situation encountered in the renormalisable and ...

Branching fractions of semileptonic D and \(D_s\) decays from the covariant light-front quark model

Based on the predictions of the relevant form factors from the covariant light-front quark model, we show the branching fractions for the \(D (D_s) \rightarrow (P,\,S,\,V,\,A)\,\ell \nu _\ell \) (\(\ell =e\) or \(\mu \)) decays, where P denotes the pseudoscalar meson, S the scalar meson with a mass above 1 GeV, V the vector meson and A the axial-vector one. Comparison with the ...

Gravitational effective action at second order in curvature and gravitational waves

We consider the full effective theory for quantum gravity at second order in curvature including non-local terms. We show that the theory contains two new degrees of freedom beyond the massless graviton: namely a massive spin-2 ghost and a massive scalar field. Furthermore, we show that it is impossible to fine-tune the parameters of the effective action to eliminate completely the ...

Effective Higgs theories in supersymmetric grand unification

The effective Higgs theories at the TeV scale in supersymmetric \(\mathrm{SU}(5)\) grand unification models are systematically derived. Restricted to extensions on \(\mathbf {5}_{H}\) containing the Higgs sector we show that only two types of real (vector-like) models and one type of chiral model are found to be consistent with perturbative grand unification. While the chiral model ...

Revisiting the decoupling effects in the running of the Cosmological Constant

We revisit the decoupling effects associated with heavy particles in the renormalization group running of the vacuum energy in a mass-dependent renormalization scheme. We find the running of the vacuum energy stemming from the Higgs condensate in the entire energy range and show that it behaves as expected from the simple dimensional arguments meaning that it exhibits the quadratic ...

Probing new physics in \(B \rightarrow D \ell ^+ \ell ^-\) decays by using angular asymmetries

We present a fully general, model-independent study of a few rare semileptonic B decays that get dominant contributions from W-annihilation and W-exchange diagrams, in particular \(B^0 \rightarrow \overline{D}{} ^0 \ell ^+\ell ^-\), where \(\ell = e,\mu \). We consider the most general Lagrangian for the decay, and define three angular asymmetries in the Gottfried–Jackson frame, ...

Relativistic scattering of fermions in quaternionic quantum mechanics

In this article, we propose a quaternionic version of the Dirac equation in the presence of scalar and vector potentials. It has been shown that in complex limit of such an equation, the complex version of this equation can be covered. After setting a quaternionic form for the Dirac delta potential, scattering due to the considered interaction has been studied. Wave functions and ...

Search for physics beyond the standard model in events with two leptons of same sign, missing transverse momentum, and jets in proton–proton collisions at \(\sqrt{s} = 13\,\text {TeV} \)

A data sample of events from proton–proton collisions with two isolated same-sign leptons, missing transverse momentum, and jets is studied in a search for signatures of new physics phenomena by the CMS Collaboration at the LHC. The data correspond to an integrated luminosity of 35.9\(\,\text {fb}^{-\text {1}}\), and a center-of-mass energy of 13\(\,\text {TeV}\). The properties of ...

Fermionic field perturbations of a three-dimensional Lifshitz black hole in conformal gravity

We study the propagation of massless fermionic fields in the background of a three-dimensional Lifshitz black hole, which is a solution of conformal gravity. The black-hole solution is characterized by a vanishing dynamical exponent. Then we compute analytically the quasinormal modes, the area spectrum, and the absorption cross section for fermionic fields. The analysis of the ...