The European Physical Journal C

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

List of Papers (Total 3,622)

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...

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...

Properties of nucleon in nuclear matter: once more

We calculate the mass and residue of the nucleon in nuclear matter in the frame work of QCD sum rules using the nucleon’s interpolating current with an arbitrary mixing parameter. We evaluate the effects of the nuclear medium on these quantities and compare the results obtained with the existing theoretical predictions. The results are also compared with those obtained in vacuum...

Lessons for SUSY from the LHC after the first run

A review of direct searches for new particles predicted by Supersymmetry (SUSY) after the first run of the LHC is proposed. This review is based on the results provided by the ATLAS and CMS experiments.

Implications of the Higgs discovery for the MSSM

The implications of the discovery of the Higgs boson at the LHC with a mass of approximately 125 GeV are summarised in the context of the minimal supersymmetric extension of the Standard Model, the MSSM. Discussed are the implications from the measured mass and production/decay rates of the observed particle and from the constraints in the search for the heavier Higgs states at...

Neutron production rates by inverse-beta decay in fully ionized plasmas

Recently we showed that the nuclear transmutation rates are largely overestimated in the Widom–Larsen theory of the so-called ‘Low Energy Nuclear Reactions’. Here we show that unbound plasma electrons are even less likely to initiate nuclear transmutations.

Exotic \(J^{PC}=1^{-+}\) mesons in a holographic model of QCD

Mesons with quantum numbers \(J^{PC}\!=\!1^{-+}\) cannot be represented as simple quark–antiquark pairs. We explore hybrid configurations in the light meson sector comprising a quark, an antiquark and an excited gluon, studying the properties of such states in a phenomenological model inspired by the gauge/gravity correspondence. The computed mass, compared to the experimental...

Nuclear structure functions at low- \(x\) in a holographic approach

Nuclear effects in deep inelastic scattering at low \(x\) are phenomenologically described changing the typical dynamical and/or kinematical scales characterizing the free nucleon case. In a holographic approach, this rescaling is an analytical property of the computed structure function \(F_2(x,Q^2)\). This function is given by the sum of a conformal term and of a contribution...

Low-redshift formula for the luminosity distance in a LTB model with cosmological constant

We calculate the low-redshift Taylor expansion for the luminosity distance for an observer at the center of a spherically symmetric matter inhomogeneity with a non-vanishing cosmological constant. We then test the accuracy of the formulas comparing them to the numerical calculation for different cases for both the luminosity distance and the radial coordinate. The formulas can be...

The background in the \(0\nu \beta \beta \) experiment Gerda

The GERmanium Detector Array (Gerda) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double beta (\(0\nu \beta \beta \)) decay of \(^{76}\)Ge. The signature of the signal is a monoenergetic peak at 2039 keV, the \(Q_{\beta \beta }\) value of the decay. To avoid bias in the signal search, the present analysis does not consider all...

Double lepton pair production with electron capture in relativistic heavy-ion collisions

We present a theoretical study of a double lepton-pair production in ultra-relativistic collision between two bare ions. Special emphasis is placed to processes in which creation of (at least one) \(e^+ e^-\) pair is accompanied by the capture of an electron into a bound ionic state. To evaluate the probability and cross section of these processes we employ two approaches based...

Measurement of the top-quark mass in all-jets \(\hbox {t}\bar{\mathrm{t}}\) events in pp collisions at \(\sqrt{s}=7\) TeV

The mass of the top quark is measured using a sample of \(\hbox {t}\bar{\mathrm{t}}\) candidate events with at least six jets in the final state. The sample is selected from data collected with the CMS detector in pp collisions at \(\sqrt{s}=7\) TeV in 2011 and corresponds to an integrated luminosity of 3.54 \(\hbox {fb}^{-1}\). The mass is reconstructed for each event employing...

Exact results in two-dimensional chiral hydrodynamics with gravitational anomalies

An exact formulation of two-dimensional chiral hydrodynamics with diffeomorphism and conformal anomalies is provided. The constitutive relation involving the stress tensor is computed. It reveals a one parameter class of solutions which is a new result. For a particular value of this parameter, the results found in the gradient expansion scheme are reproduced. Moreover, the...