The European Physical Journal C

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

List of Papers (Total 3,079)

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 ...

Identification and rejection of pile-up jets at high pseudorapidity with the ATLAS detector

The rejection of forward jets originating from additional proton–proton interactions (pile-up) is crucial for a variety of physics analyses at the LHC, including Standard Model measurements and searches for physics beyond the Standard Model. The identification of such jets is challenging due to the lack of track and vertex information in the pseudorapidity range \(|\eta |>2.5\). ...

Possible \(D^{(*)}\bar{D}^{(*)}\) and \(B^{(*)}\bar{B}^{(*)}\) molecular states in the extended constituent quark models

The possible neutral \(D^{(*)}\bar{D}^{(*)}\) and \(B^{(*)}\bar{B}^{(*)}\) molecular states are studied in the framework of the constituent quark models, which is extended by including the s-channel one-gluon exchange. Using different types of quark–quark potentials, we solve the four-body Schrödinger equation by means of the Gaussian expansion method. The bound states of ...

Constraining f(T) teleparallel gravity by big bang nucleosynthesis

We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f(T) gravity. The three most studied viable f(T) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find ...

Accretion onto a noncommutative geometry inspired black hole

The spherically symmetric accretion onto a noncommutative (NC) inspired Schwarzschild black hole is treated for a polytropic fluid. The critical accretion rate \(\dot{M}\), sonic speed \(a_s\) and other flow parameters are generalized for the NC inspired static black hole and compared with the results obtained for the standard Schwarzschild black holes. Also explicit expressions ...

ALPs effective field theory and collider signatures

We study the leading effective interactions between the Standard Model fields and a generic singlet CP-odd (pseudo-) Goldstone boson. Two possible frameworks for electroweak symmetry breaking are considered: linear and non-linear. For the latter case, the basis of leading effective operators is determined and compared with that for the linear expansion. Associated phenomenological ...

Gravity stabilizes itself

We show that a possible resolution to the stabilization of an extra spatial dimension (radion) can be obtained solely in the context of gravitational dynamics itself without the necessity of introducing any external stabilizing field. In this scenario the stabilized value of the radion field gets determined in terms of the parameters appearing in the higher curvature gravitational ...

Isospin analysis of charmless B-meson decays

We discuss the determination of the CKM angle \(\alpha \) using the non-leptonic two-body decays \(B\rightarrow \pi \pi \), \(B\rightarrow \rho \rho \) and \(B\rightarrow \rho \pi \) using the latest data available. We illustrate the methods used in each case and extract the corresponding value of \(\alpha \). Combining all these elements, we obtain the determination \(\alpha ...

Nuclear suppression of the \(\phi \) meson yields with large \(p_T\) at the RHIC and the LHC

We calculate \(\phi \) meson transverse momentum spectra in \(\mathrm{p}+\mathrm{p}\) collisions as well as their nuclear suppressions in central \(\mathrm{A}+\mathrm{A}\) collisions both at the RHIC and the LHC in LO and NLO with the QCD-improved parton model. We have included the parton energy loss effect in a hot/dense QCD medium with the effectively medium-modified \(\phi \) ...

Status of the scalar singlet dark matter model

One of the simplest viable models for dark matter is an additional neutral scalar, stabilised by a \(\mathbb {Z}_2\) symmetry. Using the GAMBIT package and combining results from four independent samplers, we present Bayesian and frequentist global fits of this model. We vary the singlet mass and coupling along with 13 nuisance parameters, including nuclear uncertainties relevant ...

Insight into particle production mechanisms via angular correlations of identified particles in pp collisions at \(\sqrt{\mathrm{s}}=7\) TeV

Two-particle angular correlations were measured in pp collisions at \(\sqrt{s} = 7\) TeV for pions, kaons, protons, and lambdas, for all particle/anti-particle combinations in the pair. Data for mesons exhibit an expected peak dominated by effects associated with mini-jets and are well reproduced by general purpose Monte Carlo generators. However, for baryon–baryon and ...

Gravitational waves from a supercooled electroweak phase transition and their detection with pulsar timing arrays

We investigate the properties of a stochastic gravitational wave background produced by a first-order electroweak phase transition in the regime of extreme supercooling. We study a scenario whereby the percolation temperature that signifies the completion of the transition, \(T_\mathrm{p}\), is as low as a few MeV (nucleosynthesis temperature), while most of the true vacuum bubbles ...

Characterisation of irradiated thin silicon sensors for the CMS phase II pixel upgrade

The high luminosity upgrade of the Large Hadron Collider, foreseen for 2026, necessitates the replacement of the CMS experiment’s silicon tracker. The innermost layer of the new pixel detector will be exposed to severe radiation, corresponding to a 1 MeV neutron equivalent fluence of up to \(\Phi _{eq} = 2 \times 10^{16}\) cm\(^{-2}\), and an ionising dose of \({\approx } 5\) MGy ...

Charged thin-shell gravastars in noncommutative geometry

In this paper we construct a charged thin-shell gravastar model within the context of noncommutative geometry. To do so, we choose the interior of the nonsingular de Sitter spacetime with an exterior charged noncommutative solution by cut-and-paste technique and apply the generalized junction conditions. We then investigate the stability of a charged thin-shell gravastar under ...

Measurement of \(WW/WZ \rightarrow \ell \nu q q^{\prime }\) production with the hadronically decaying boson reconstructed as one or two jets in pp collisions at \(\sqrt{s} =8~\text {TeV}\) with ATLAS, and constraints on anomalous gauge couplings

This paper presents a study of the production of WW or WZ boson pairs, with one W boson decaying to \(e\nu \) or \(\mu \nu \) and one W or Z boson decaying hadronically. The analysis uses \(20.2~\text{ fb }^{-1}\) of \(\sqrt{s} =8~\text {TeV}\) pp collision data, collected by the ATLAS detector at the Large Hadron Collider. Cross-sections for WW / WZ production are measured in ...

AIC and BIC for cosmological interacting scenarios

In this work we study linear and nonlinear cosmological interactions, which depend on dark matter and dark energy densities in the framework of general relativity. By using the Akaike information criterion (AIC) and the bayesian information criterion (BIC) with data from SnIa (Union 2.1 and binned JLA), \(\mathrm{H(z)}\), BAO and CMB we compare the interacting models among ...

A non-perturbative study of matter field propagators in Euclidean Yang–Mills theory in linear covariant, Curci–Ferrari and maximal Abelian gauges

In this work, we study the propagators of matter fields within the framework of the refined Gribov–Zwanziger theory, which takes into account the effects of the Gribov copies in the gauge-fixing quantization procedure of Yang–Mills theory. In full analogy with the pure gluon sector of the refined Gribov–Zwanziger action, a non-local long-range term in the inverse of the ...

Superconductor in a weak static gravitational field

We provide the detailed calculation of a general form for Maxwell and London equations that takes into account gravitational corrections in linear approximation. We determine the possible alteration of a static gravitational field in a superconductor making use of the time-dependent Ginzburg–Landau equations, providing also an analytic solution in the weak field condition. Finally, ...

High- \(p_T\) dilepton tails and flavor physics

We investigate the impact of flavor-conserving, non-universal quark-lepton contact interactions on the dilepton invariant mass distribution in \(p~p \rightarrow \ell ^+ \ell ^-\) processes at the LHC. After recasting the recent ATLAS search performed at 13 TeV with 36.1 fb\(^{-1}\) of data, we derive the best up-to-date limits on the full set of 36 chirality-conserving four-fermion ...

Phase space of modified Gauss–Bonnet gravity

We investigate the evolution of non-vacuum Friedmann–Lemaître–Robertson–Walker (FLRW) spacetimes with any spatial curvature in the context of Gauss–Bonnet gravity. The analysis employs a new method which enables us to explore the phase space of any specific theory of this class. We consider several examples, discussing the transition from a decelerating into an acceleration ...

Dilaton field released under collision of dilatonic black holes with Gauss–Bonnet term

We investigate the upper limit of the gravitational radiation released upon the collision of two dilatonic black holes by analyzing the Gauss–Bonnet term. Dilatonic black holes have a dilaton hair coupled with this term. Using the laws of thermodynamics, the upper limit of the radiation is obtained, which reflected the effects of the dilaton hair. The amount of radiation released ...