The European Physical Journal C

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

List of Papers (Total 2,913)

Herwig++ physics and manual

In this paper we describe \(\mathsf{Herwig++}\) version 2.2, a general-purpose Monte Carlo event generator for the simulation of hard lepton-lepton and hadron-hadron collisions. A number of important hard scattering processes are available, together with an interface via the Les Houches Accord to specialized matrix element generators for additional processes. The simulation of ...

Di-jet production in γ γ collisions at LEP2

The production of two high-p T jets in the interactions of quasi-real photons in e + e − collisions at \(\sqrt{s_{ee}}\) from 189 GeV to 209 GeV is studied with data corresponding to an integrated e + e − luminosity of 550 pb−1. The jets reconstructed by the k ⊥ -cluster algorithm are defined within the pseudo-rapidity range −1ηp T , above 3 GeV/c. The differential di-jet ...

Collider aspects of flavor physics at high Q

This chapter of the “Flavor in the era of LHC” workshop report discusses flavor-related issues in the production and decays of heavy states at the LHC at high momentum transfer Q, both from the experimental and the theoretical perspective. We review top quark physics, and discuss the flavor aspects of several extensions of the standard model, such as supersymmetry, little Higgs ...

Revisiting unitarity corrections for electromagnetic processes in collisions of relativistic nuclei

Unitarity corrections to several electromagnetic processes in collisions of relativistic heavy nuclei are considered. They are due to the unitarity requirement for the S-matrix and correspond to the exchange of a light-by-light scattering block between colliding nuclei. We obtain improved results for the corrections to e + e − and μ + μ − pair production as well as new results for ...

Design, performance, and calibration of the CMS hadron-outer calorimeter

The Outer Hadron Calorimeter (HCAL HO) of the CMS detector is designed to measure the energy that is not contained by the barrel (HCAL HB) and electromagnetic (ECAL EB) calorimeters. Due to space limitation the barrel calorimeters do not contain completely the hadronic shower and an outer calorimeter (HO) was designed, constructed and inserted in the muon system of CMS to measure ...

Observation of the muon inner bremsstrahlung at LEP1

Muon bremsstrahlung photons converted in front of the DELPHI main tracker (TPC) in dimuon events at LEP1 were studied in two photon kinematic ranges: 0.2E γ ≤1 GeV and transverse momentum with respect to the parent muon p T c, and 1E γ ≤10 GeV and p T c. A good agreement of the observed photon rate with predictions from QED for the muon inner bremsstrahlung was found, contrary to ...

Re-evaluation of the LHC potential for the measurement of m W

We present a study of the LHC sensitivity to the W boson mass based on simulation studies. We find that both experimental and phenomenological sources of systematic uncertainties can be strongly constrained with Z measurements: the lineshape, dσ Z /dm, is robustly predicted, and its analysis provides an accurate measurement of the detector resolution and absolute scale, while the ...

Towards a measurement of the two-photon decay width of the Standard Model Higgs boson at a Photon Collider

A study of the measurement of the two photon decay width times the branching ratio of the Standard Model Higgs boson with a mass of 120 GeV in photon–photon collisions is presented, assuming a γ γ integrated luminosity of 80 fb−1 in the high energy part of the spectrum. The analysis is based on the reconstruction of the Higgs events produced in the γ γ→H process, followed by the ...

Neutrinos, axions and conformal symmetry

We demonstrate that radiative breaking of conformal symmetry (and simultaneously electroweak symmetry) in the standard model with right-chiral neutrinos and a minimally enlarged scalar sector induces spontaneous breaking of lepton number symmetry, which naturally gives rise to an axion-like particle with some unusual features. The couplings of this ‘axion’ to standard model ...

Lee-Yang circle analysis of e + e − and \(p\overline{p}\) generalized multiplicity distribution

We study the evolution of Lee-Yang zeros structure of generalized multiplicity distribution (GMD) in high energy collision. Starting our study with electron-positron e + e − scattering data, we extend the study by Chan and Chew (Z. Phys. C 55:503, 1992) on TASSO and AMY multiplicity data for \(\sqrt{s}=14\) , 22, 34.8, 43.6 and 57 GeV to the ones from DELPHI and OPAL Collaboration ...

γ–hadron correlation measurements to study jets fragmentation with ALICE at LHC

The possibility to study the fragmentation function of jets with energies below 50 GeV, which cannot be reconstructed in the heavy-ion environment, is explored. We propose to measure the imbalance distribution between prompt photon and charged hadrons with the ALICE experiment at LHC. In the present article, the case of proton–proton collisions at \(\sqrt{s}=14\) TeV is examined ...

Prospects for the discovery of 4th family quarks with the ATLAS detector

The pair production of heavy fourth-generation quarks, which are predicted under the hypothesis of flavor democracy, is studied using tree-level Monte Carlo generators and fast detector simulation. Two heavy-quark mass values, 500 and 750 GeV, are considered with the assumption that the fourth family mixes primarily with the two light families. It is shown that a clear signature ...

B, D and K decays

The present report documents the results of Working Group 2: B, D and K decays, of the workshop on Flavor in the Era of the LHC, held at CERN from November 2005 through March 2007. With the advent of the LHC, we will be able to probe New Physics (NP) up to energy scales almost one order of magnitude larger than it has been possible with present accelerator facilities. While direct ...

Flavor physics of leptons and dipole moments

This chapter of the report of the “Flavor in the era of the LHC” Workshop discusses the theoretical, phenomenological and experimental issues related to flavor phenomena in the charged lepton sector and in flavor conserving CP-violating processes. We review the current experimental limits and the main theoretical models for the flavor structure of fundamental particles. We analyze ...

First results from DAMA/LIBRA and the combined results with DAMA/NaI

The highly radiopure ≃ 250 kg NaI(Tl) DAMA/LIBRA set-up is running at the Gran Sasso National Laboratory of the INFN. In this paper the first result obtained by exploiting the model independent annual modulation signature for Dark Matter (DM) particles is presented. It refers to an exposure of 0.53 ton×yr. The collected DAMA/LIBRA data satisfy all the many peculiarities of the DM ...

Reconstruction of cosmic and beam-halo muons with the CMS detector

The powerful muon and tracker systems of the CMS detector together with dedicated reconstruction software allow precise and efficient measurement of muon tracks originating from proton-proton collisions. The standard muon reconstruction algorithms, however, are inadequate to deal with muons that do not originate from collisions. This note discusses the design, implementation, and ...

Statistics in the landscape of intersecting brane models

An approach towards a statistical survey of four-dimensional supersymmetric vacua in the string theory landscape is described and illustrated with three examples of ensembles of intersecting D-brane models. The question whether it is conceivable to make predictions based on statistical distributions is discussed. Especially interesting in this context are possible correlations ...

Comparison of Geant4 hadron generation with data from the interactions with beryllium nuclei of +8.9 GeV/c protons and pions and −8.0 GeV/c pions

Hadron generation in the Geant4 simulation tool kit is compared with inclusive spectra of secondary protons and pions from the interactions with beryllium nuclei of +8.9 GeV/c protons and pions, and of −8.0 GeV/c pions. The data were taken in 2002 at the CERN Proton Synchrotron with the HARP spectrometer. We report on significant disagreements between data and Monte Carlo ...

Non-standard interactions using the OPERA experiment

We investigate the implications of non-standard interactions on neutrino oscillations in the OPERA experiment. In particular, we study the non-standard interaction parameter ε μ τ . We show that the OPERA experiment has a unique opportunity to reduce the allowed region for this parameter compared with other experiments such as the MINOS experiment, mostly due to the higher neutrino ...

HELAS and MadGraph/MadEvent with spin-2 particles

Fortran subroutines to calculate helicity amplitudes with massive spin-2 particles (massive gravitons), which couple to the standard model particles via the energy momentum tensor, are added to the HELAS (HELicity Amplitude Subroutines) library. They are coded in such a way that arbitrary scattering amplitudes with one graviton production and its decays can be generated ...

Amplitude analysis of high statistics results on γγ→π+π- and the two photon width of isoscalar states

We perform an amplitude analysis of the world published data on γγ→π+π- and π0π0. These are dominated in statistics by the recently published results from Belle on the charged pion channel. Nevertheless, having only limited angular information, a range of solutions remain possible. We present two solutions with Γ(f0(980)→γγ)=0.42 and 0.10 keV, and Γ(f2(1270)→γγ)=3.14±0.20 and 3.82 ...

CBBN in the CMSSM

Catalyzed big bang nucleosynthesis (CBBN) can lead to overproduction of 6Li in gravitino dark matter scenarios in which the lighter stau is the lightest standard model superpartner. Based on a treatment using the state-of-the-art result for the catalyzed 6Li production cross section, we update the resulting constraint within the framework of the constrained minimal supersymmetric ...

Identification of the K*± resonance decay by topological cuts and multivariate discrimination methods

A study of the identification of the short-lived K*± resonance via its decay into a K0 s and a charged pion has been carried out. A sample of minimum bias PYTHIA pp collision events has been simulated and fully reconstructed in the ALICE detector. Traditional methods based on multidimensional topological cuts and artificial neural networks with different architectures have been ...