The European Physical Journal C

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

List of Papers (Total 3,584)

Gribov gap equation at finite temperature

In this paper the Gribov gap equation at finite temperature is analyzed. The solutions of the gap equation (which depend explicitly on the temperature) determine the structure of the gluon propagator within the semi-classical Gribov approach. The present analysis is consistent with the standard confinement scenario for low temperatures, while for high enough temperatures...

SModelS: a tool for interpreting simplified-model results from the LHC and its application to supersymmetry

We present a general procedure to decompose Beyond the Standard Model (BSM) collider signatures presenting a \(\mathbb {Z}_2\) symmetry into Simplified Model Spectrum (SMS) topologies. Our method provides a way to cast BSM predictions for the LHC in a model independent framework, which can be directly confronted with the relevant experimental constraints. Our concrete...

Possible assignments of the \(X(3872)\) , \(Z_c(3900)\) , and \(Z_b(10610)\) as axial-vector molecular states

In this article, we construct both the color singlet–singlet type and the octet–octet type currents to interpolate \(X(3872)\), \(Z_c(3900)\), and \(Z_b(10610)\), and we calculate the vacuum condensates up to dimension-10 in the operator product expansion. Then we study the axial-vector hidden charm and hidden bottom molecular states with the QCD sum rules, explore the energy...

Large \(N\) approach to Kaon decays and mixing 28 years later: \(\Delta I=1/2\) rule, \(\hat{B}_K\) , and \(\Delta M_K\)

We review and update our results for \(K\rightarrow \pi \pi \) decays and \(K^0\)–\(\bar{K}^0\) mixing obtained by us in the 1980s within an analytic approximate approach based on the dual representation of QCD as a theory of weakly interacting mesons for large \(N\), where \(N\) is the number of colors. In our analytic approach the Standard Model dynamics behind the enhancement...

Measurement of \(\psi {(2S)} \) polarisation in \(pp\) collisions at \(\sqrt{s}\) = 7 TeV

The polarisation of prompt \(\psi {(2S)} \) mesons is measured by performing an angular analysis of \(\psi {(2S)} \!\rightarrow \mu ^+\mu ^- \) decays using proton-proton collision data, corresponding to an integrated luminosity of 1.0\(\,\text{ fb }^{-1} \), collected by the LHCb detector at a centre-of-mass energy of 7 TeV. The polarisation is measured in bins of transverse...

Gravity’s Rainbow induces topology change

In this work, we explore the possibility that quantum fluctuations induce a topology change, in the context of Gravity’s Rainbow. A semiclassical approach is adopted, where the graviton one-loop contribution to a classical energy in a background spacetime is computed through a variational approach with Gaussian trial wave functionals. The energy density of the graviton one-loop...

En-gauging naturalness

The discovery of a 125.5 GeV Higgs with standard model-like couplings and naturalness considerations motivate gauge extensions of the MSSM. We analyse two variants of such an extension and carry out a phenomenological study of regions of the parameter space satisfying current direct and indirect constraints, employing state-of-the-art two-loop RGE evolution and GMSB boundary...

Microscopic thin-shell wormholes in magnetic Melvin universe

We construct thin-shell wormholes in the magnetic Melvin universe. It is shown that in order to make a TSW in the Melvin spacetime the radius of the throat cannot be larger than \(\frac{2}{B_{0}}\), in which \(B_{0}\) is the magnetic field constant. We also analyze the stability of the constructed wormhole in terms of a linear perturbation around the equilibrium point. In our...

Infrared saturation and phases of gauge theories with BRST symmetry

We investigate the infrared limit of the quantum equation of motion of the gauge boson propagator in various gauges and models with a BRST symmetry. We find that the saturation of this equation at low momenta distinguishes between the Coulomb, Higgs and confining phase of the gauge theory. The Coulomb phase is characterized by a massless gauge boson. Physical states contribute to...

Higgs quartic coupling and neutrino sector evolution in 2UED models

Two compact universal extra-dimensional models are an interesting class of models for different theoretical and phenomenological issues, such as the justification of having three standard model fermion families, suppression of proton decay rate, dark matter parity from relics of the six-dimensional Lorentz symmetry, origin of masses and mixings in the standard model. However...

Anomalous effective action, Noether current, Virasoro algebra and Horizon entropy

Several investigations show that in a very small length scale there exist corrections to the entropy of black hole horizon. Due to fluctuations of the background metric and the external fields the action incorporates corrections. In the low energy regime, the one-loop effective action in four dimensions leads to trace anomaly. We start from the Noether current corresponding to...

Different approaches to calculate the \(K^{\pm }\rightarrow \pi ^{\pm }\pi ^0e^+e^-\) decay width

The rare \(K^\pm \rightarrow \pi ^\pm \pi ^0 e^+e^-\) decay, currently under analysis by the NA62 Collaboration, is considered. We have followed two theoretical approaches to calculate the differential decay width—in the kaon rest frame, where we use Cabibbo–Maksymowicz variables, and in the center-of-mass system of the lepton pair. The latter essentially simplifies the...

On the structure constants of volume preserving diffeomorphism algebra

Regularizing a volume preserving diffeomorphism (VPD) is equivalent to a long standing problem, namely regularizing a Nambu–Poisson bracket. In this paper, as a first step toward regularizing VPD, we find general complete independent bases of VPD algebra. Especially, we find a complete independent basis that gives simple structure constants, where three area preserving...

Universality of identified hadron production in \(pp\) collisions

The shapes of invariant differential cross section for identified \(\pi ^{\pm },K^{\pm }, p\) and \(\overline{p}\) production as a function of transverse momentum measured in \(pp\) collisions by the PHENIX detector are analyzed in terms of a recently introduced approach. Simultaneous fits of these data to the sum of exponential and power-law terms show a significant difference...

Black hole interior mass formula

We argue by explicit computations that, although the area product, horizon radii product, entropy product, and irreducible mass product of the event horizon and Cauchy horizon are universal, the surface gravity product, the surface temperature product and the Komar energy product of the said horizons do not seem to be universal for Kerr–Newman black hole spacetimes. We show the...

Electrically charged one-and-a-half monopole solution

Recently, we have discussed the coexistence of a finite energy one-half monopole and a ’t Hooft–Polyakov monopole of opposite magnetic charges. In this paper, we would like to introduce electric charge into this new monopoles configuration, thus creating a one-and-a-half dyon. This new dyon possesses finite energy, magnetic dipole moment, and angular momentum and is able to...

SUSY: the early years (1966–1976)

We describe the early evolution of theories with fermion–boson symmetry.

SUSY: Quo Vadis?

Given that there is currently no direct evidence for supersymmetric particles at the LHC it is timely to re-evaluate the need for low scale supersymmetry and to ask whether it is likely to be discoverable by the LHC running at its full energy. We review the status of simple SUSY extensions of the Standard Model in the light of the Higgs discovery and the non-observation of...

The supersymmetric standard model

Supersymmetric extensions of the standard model lead us to expect superpartners for all particles, spin-0 squarks and sleptons and spin-\(\frac{1}{2}\) gluinos, charginos, and neutralinos, with an odd \(R\)-parity making the lightest one stable. The electroweak breaking is induced by a pair of spin-0 doublets, leading to several charged and neutral BE-Higgs bosons. These theories...

Generalized Langevin equation with colored noise description of the stochastic oscillations of accretion disks

We consider a description of the stochastic oscillations of the general relativistic accretion disks around compact astrophysical objects interacting with their external medium based on a generalized Langevin equation with colored noise and on the fluctuation–dissipation theorems. The former accounts for the general memory and retarded effects of the frictional force. The...

Associated production of Higgs at linear collider in the inert Higgs Doublet Model

We study the correlation between the Standard Model Higgs decay \(h\rightarrow \gamma \gamma \) and \(h\rightarrow Z \gamma \) in the Inert Higgs Doublet Model. It is found that these two one-loop-induced decays are positively correlated, with the latter channel having slightly smaller branching ratio than the former one. At the Linear Collider, we study the interplay of the off...

SUSY dark matter(s)

We review the status of different dark-matter candidates in the context of supersymmetric models, in particular the neutralino as a realization of the WIMP mechanism and the gravitino. We give a summary of the recent bounds in direct and indirect detection and also of the LHC searches relevant for the dark-matter question. We also discuss the implications of the Higgs discovery...

Composite Higgses

For the closing article in this volume on supersymmetry, we consider the alternative options to SUSY theories: we present an overview of composite Higgs models in light of the discovery of the Higgs boson. The small value of the physical Higgs mass suggests that the Higgs quartic is likely loop generated; thus models with tree-level quartics will generically be more tuned. We...

The strings connection: MSSM-like models from strings

String theory constructions towards the MSSM allow us to identify some general properties that could be relevant for tests at the LHC. They originate from the geometric structure of compactification and the location of fields in extra-dimensional space. Within the framework of the heterotic MiniLandscape we extract some generic lessons for supersymmetric model building. Among...

Supersymmetric fits after the Higgs discovery and implications for model building

The data from the first run of the LHC at 7 and 8 TeV, together with the information provided by other experiments such as precision electroweak measurements, flavour measurements, the cosmological density of cold dark matter and the direct search for the scattering of dark matter particles in the LUX experiment, provide important constraints on supersymmetric models. Important...