The European Physical Journal C

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

List of Papers (Total 3,650)

Closing in on the radiative weak chiral couplings

We point out that, given the current experimental status of radiative kaon decays, a subclass of the \(\mathcal{O} (p^4)\) counterterms of the weak chiral lagrangian can be determined in closed form. This involves in a decisive way the decay \(K^\pm \rightarrow \pi ^\pm \pi ^0 l^+ l^-\), currently being measured at CERN by the NA48/2 and NA62 collaborations. We show that...

Generalizing the $$\mathfrak {bms}_{3}$$ and 2D-conformal algebras by expanding the Virasoro algebra

By means of the Lie algebra expansion method, the centrally extended conformal algebra in two dimensions and the \(\mathfrak {bms}_{3}\) algebra are obtained from the Virasoro algebra. We extend this result to construct new families of expanded Virasoro algebras that turn out to be infinite-dimensional lifts of the so-called \(\mathfrak {B}_{k}\), \(\mathfrak {C}_{k}\) and...

Constraints on low energy QCD parameters from $$\eta \rightarrow 3\pi $$ and $$\pi \pi $$ππ scattering

The \(\eta \,\rightarrow \,3\pi \) decays are a valuable source of information on low energy QCD. Yet they were not used for an extraction of the three flavor chiral symmetry breaking order parameters until now. We use a Bayesian approach in the framework of resummed chiral perturbation theory to obtain constraints on the quark condensate and pseudoscalar decay constant in the...

$$\pi ^{0}$$ and $$\eta $$η meson production in proton-proton collisions at $$\sqrt{s}=8$$s=8 TeV

An invariant differential cross section measurement of inclusive \(\pi ^{0}\) and \(\eta \) meson production at mid-rapidity in pp collisions at \(\sqrt{s}=8\) TeV was carried out by the ALICE experiment at the LHC. The spectra of \(\pi ^{0}\) and \(\eta \) mesons were measured in transverse momentum ranges of \(0.3<p_{ \text{ T }} <35\) \(\text{ GeV/c }\) and \(0.5<p_{ \text{ T...

Non-relativistic approximate numerical ideal-magneto-hydrodynamics of (1+1D) transverse flow in Bjorken scenario

In this study, we investigate the impact of the magnetic field on the evolution of the transverse flow of QGP matter in the magneto-hydrodynamic (MHD) framework. We assume that the magnetic field is perpendicular to the reaction plane and then we solve the coupled Maxwell and conservation equations in (1+1D) transverse flow, within the Bjorken scenario. We consider a QGP with...

Cosmological tests with strong gravitational lenses using Gaussian processes

Strong gravitational lenses provide source/lens distance ratios \({\mathcal {D}}_{\mathrm{obs}}\) useful in cosmological tests. Previously, a catalog of 69 such systems was used in a one-on-one comparison between the standard model, \(\varLambda \)CDM, and the \(R_{\mathrm{h}}=ct\) universe, which has thus far been favored by the application of model selection tools to many other...

Likelihood analysis of the pMSSM11 in light of LHC 13-TeV data

We use MasterCode to perform a frequentist analysis of the constraints on a phenomenological MSSM model with 11 parameters, the pMSSM11, including constraints from \(\sim 36\)/fb of LHC data at 13 TeV and PICO, XENON1T and PandaX-II searches for dark matter scattering, as well as previous accelerator and astrophysical measurements, presenting fits both with and without the \((g-2...

Charged string loops in Reissner–Nordström black hole background

We study the motion of current carrying charged string loops in the Reissner–Nordström black hole background combining the gravitational and electromagnetic field. Introducing new electromagnetic interaction between central charge and charged string loop makes the string loop equations of motion to be non-integrable even in the flat spacetime limit, but it can be governed by an...

What if gravity becomes really repulsive in the future?

The current acceleration of the Universe is one of the most puzzling issues in theoretical physics nowadays. We are far from giving an answer in this letter to the question of its nature. Yet, with the observations we have at hand, we analyse the different patterns that the gravitational potential can show in the future. Surprisingly, gravity not only can get weaker in the near...

Analytical study of charged boson stars with large scalar self-couplings

We give good approximate analytic solutions for spherical charged boson stars in the large scalar-self-coupling limit in general relativity. We show that if the charge e and mass m of the scalar field nearly satisfy the critical relation \(e^2\approx Gm^2\) (where G is the Newton constant), our analytic expressions for stable solutions agree well with the numerical solutions.

Width of a two-body coupled-channel resonance

We study the width of a two-body resonance in a coupled-channel system. We demonstrate how the width does not come only determined by the available phase space for its decay to the detection channel, but it greatly depends on the relative position of the mass of the resonance with respect to the masses of the coupled-channels generating the state. Our results are consistent with...

Observation of $$\Xi _{c}(2930)^0$$ and updated measurement of $$B^{-} \rightarrow K^{-} \Lambda _{c}^{+} \bar{\Lambda }_{c}^{-}$$B-→K-Λc+Λ¯c- at Belle

We report the first observation of the \(\Xi _{c}(2930)^0\) charmed-strange baryon with a significance greater than 5\(\sigma \). The \(\Xi _{c}(2930)^0\) is found in its decay to \(K^- \Lambda _{c}^+\) in \(B^{-} \rightarrow K^{-} \Lambda _{c}^{+} \bar{\Lambda }_{c}^{-}\) decays. The measured mass and width are \([2928.9 \pm 3.0(\mathrm stat.)^{+0.9}_{-12.0}(\mathrm syst...

Does space-time torsion determine the minimum mass of gravitating particles?

We derive upper and lower limits for the mass–radius ratio of spin-fluid spheres in Einstein–Cartan theory, with matter satisfying a linear barotropic equation of state, and in the presence of a cosmological constant. Adopting a spherically symmetric interior geometry, we obtain the generalized continuity and Tolman–Oppenheimer–Volkoff equations for a Weyssenhoff spin fluid in...

Scale-dependent polytropic black hole

In the present work we study the scale-dependence of polytropic non-charged black holes in (3+1)-dimensional space-times assuming a cosmological constant. We allow for scale-dependence of the gravitational and cosmological couplings, and we solve the corresponding generalized field equations imposing the null energy condition. Besides, some properties, such as horizon structure...

Constraints on Horndeski theory using the observations of Nordtvedt effect, Shapiro time delay and binary pulsars

Alternative theories of gravity not only modify the polarization contents of the gravitational wave, but also affect the motions of the stars and the energy radiated away via the gravitational radiation. These aspects leave imprints in the observational data, which enables the test of general relativity and its alternatives. In this work, the Nordtvedt effect and the Shapiro time...

A search for pair-produced resonances in four-jet final states at $$\sqrt{s}=13$$$$\text {TeV}$$TeV with the ATLAS detector

A search for massive coloured resonances which are pair-produced and decay into two jets is presented. The analysis uses 36.7 fb\(^{-1}\) of \(\sqrt{s}\) = 13 TeV pp collision data recorded by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the background prediction is observed. Results are interpreted in a SUSY simplified model where the lightest...

The impact of LHC jet data on the MMHT PDF fit at NNLO

We investigate the impact of the high precision ATLAS and CMS 7 TeV measurements of inclusive jet production on the MMHT global PDF analysis at next-to-next-to-leading order (NNLO). This is made possible by the recent completion of the long-term project to calculate the NNLO corrections to the hard cross section. We find that a good description of the ATLAS data is not possible...

Simple cosmological model with inflation and late times acceleration

In the framework of polynomial Palatini cosmology, we investigate a simple cosmological homogeneous and isotropic model with matter in the Einstein frame. We show that in this model during cosmic evolution, early inflation appears and the accelerating phase of the expansion for the late times. In this frame we obtain the Friedmann equation with matter and dark energy in the form...

Uncovering novel phase structures in $$\Box ^k$$ scalar theories with the renormalization group

We present a detailed version of our recent work on the RG approach to multicritical scalar theories with higher derivative kinetic term \(\phi (-\Box )^k\phi \) and upper critical dimension \(d_c = 2nk/(n-1)\). Depending on whether the numbers k and n have a common divisor two classes of theories have been distinguished. For coprime k and \(n-1\) the theory admits a Wilson...

Pre-inflation from the multiverse: can it solve the quadrupole problem in the cosmic microwave background?

We analyze a quantized toy model of a universe undergoing eternal inflation using a quantum-field-theoretical formulation of the Wheeler–DeWitt equation. This so-called third quantization method leads to the picture that the eternally inflating universe is converted to a multiverse in which sub-universes are created and exhibit a distinctive phase in their evolution before...

Reconstructing warm inflation

The reconstruction of a warm inflationary universe model from the scalar spectral index \(n_S(N)\) and the tensor to scalar ratio r(N) as a function of the number of e-folds N is studied. Under a general formalism we find the effective potential and the dissipative coefficient in terms of the cosmological parameters \(n_S\) and r considering the weak and strong dissipative stages...

Compact stars in the non-minimally coupled electromagnetic fields to gravity

We investigate the gravitational models with the non-minimal \(Y(R)F^2\) coupled electromagnetic fields to gravity, in order to describe charged compact stars, where Y(R) denotes a function of the Ricci curvature scalar R and \(F^2\) denotes the Maxwell invariant term. We determine two parameter family of exact spherically symmetric static solutions and the corresponding non...

Running of the spectral index in deformed matter bounce scenarios with Hubble-rate-dependent dark energy

As a deformed matter bounce scenario with a dark energy component, we propose a deformed one with running vacuum model (RVM) in which the dark energy density \(\rho _{\Lambda }\) is written as a power series of \(H^2\) and \(\dot{H}\) with a constant equation of state parameter, same as the cosmological constant, \(w=-1\). Our results in analytical and numerical point of views...

Refractive index in generalized superconductors with Born–Infeld electrodynamics

We investigate, in the probe limit, the negative refraction in the generalized superconductors with the Born–Infeld electrodynamics. We observe that the system has a negative Depine–Lakhtakia index in the superconducting phase at small frequencies and the greater the Born–Infeld corrections the larger the range of frequencies or the range of temperatures for which the negative...

Merging NLO multi-jet calculations with improved unitarization

We present an algorithm to combine multiple matrix elements at LO and NLO with a parton shower. We build on the unitarized merging paradigm. The inclusion of higher orders and multiplicities reduce the scale uncertainties for observables sensitive to hard emissions, while preserving the features of inclusive quantities. The combination allows further soft and collinear emissions...