Search results for "Collider"
showing 10 items of 1690 documents
Discriminating between lepton number violating scalars using events with four and three charged leptons at the LHC
2013
Many Standard Model extensions predict doubly-charged scalars; in particular, all models with resonances in charged lepton-pair channels with non-vanishing lepton number; if these are pair produced at the LHC, the observation of their decay into l(-/+)l(-/+)W(-/+)W(-/+) will be necessary in order to establish their lepton-number violating character, which is generally not straightforward. Nonetheless, the analysis of events containing four charged leptons (including scalar decays into one or two taus as well as into W bosons) makes it possible to determine whether the doubly-charged excitation belongs to a multiplet with weak isospin T = 0,1/2,1,3/2 or 2 (assuming there are no excitations w…
Beta-decay half-lives of $^{70}$Kr and $^{74}$Rb
2000
Abstract Beta-decay half-lives of two nuclei close to N = Z line, 70 Kr and 74 Rb, have been measured at the ISOLDE mass-separator facility at CERN. Importance of these half-lives on two ingredients explaining existence and development of the Universe, the astrophysical nucleosynthesis and the Standard Model, are discussed.
Searching for new physics with three-particle correlations in pp collisions at the LHC
2018
New phenomena involving pseudorapidity and azimuthal correlations among final state particles in $pp$ collisions at the LHC can hint at the existence of hidden sectors beyond the Standard Model. In this paper we rely on a correlated-cluster picture of multiparticle production, which was shown to account for the ridge effect, to assess the effect of a hidden sector on three-particle correlations concluding that there is a potential signature of new physics that can be directly tested by experiments using well-known techniques.
Search for direct CP-violation in K±→π±π0π0 decays
2006
Abstract A search for direct CP-violation in K ± → π ± π 0 π 0 decay based on 47.14 million events has been performed by the NA48/2 experiment at the CERN SPS. The asymmetry in the Dalitz plot linear slopes A g = ( g + − g − ) / ( g + + g − ) is measured to be A g = ( 1.8 ± 2.6 ) × 10 −4 . The design of the experiment and the method of analysis provide good control of instrumental charge asymmetries in this measurement. The precision of the result is limited by statistics and is almost one order of magnitude better than that of previous measurements by other experiments.
Modelling jet quenching
2013
Abstract High P T measurements of hard hadrons or jets at RHIC and LHC appear contradictory and in some cases counterintuitive, but upon closer investigation they represent a coherent picture of jet-medium interaction physics which can be established with systematic comparisons of models against a large body of data. This picture is consistent with a perturbative QCD mechanism and does not require exotic assumptions. This overview outlines how several key measurements each partially constrain shower-medium interaction physics and how from the sum of those the outlines of the mechanism of jet quenching can be deduced. Most current jet results from LHC can be naturally understood in this pict…
From minijet saturation to global observables in A + A collisions at the LHC and RHIC
2014
We review the recent results from the computation of saturated next-to-leading order perturbative QCD minijet intial conditions combined with viscous hydrodynamical evolution of ultrarelativistic heavy-ion collisions at the LHC and RHIC. Comparison with experimental data is shown.
Hard dihadron correlations in heavy-ion collisions at energies available at the BNL Relativistic Heavy Ion Collider and CERN Large Hadron Collider
2011
High transverse momentum (${P}_{T}$) processes are considered to be an important tool to probe and understand the medium produced in ultrarelativistic heavy-ion collisions via the interaction of hard, perturbatively produced partons with the medium. In this context, triggered hard dihadron correlations constitute a class of observables set between hard single inclusive hadrons (dominated by the leading jet fragments) and fully reconstructed jets; while they probe some features of the perturbative QCD evolution of a parton shower in the medium, they do not suffer from the problem of finding a suitable separation between soft hadrons coming from perturbative jets and soft hadrons coming from …
Centrality dependence of forward J/ψ suppression in high energy proton–nucleus collisions
2015
The production of forward $J/\psi$ mesons in proton-nucleus collisions can provide important information on gluon saturation. In a previous work we studied this process in the Color Glass Condensate framework, describing the target using a dipole cross section fitted to HERA inclusive data and extrapolated to the case of a nuclear target using the optical Glauber model. In this work we study the centrality dependence of the nuclear suppression in this model and compare our results with recent LHC data for this observable.
Custodial vector model
2014
We analyze the Large Hadron Collider (LHC) phenomenology of heavy vector resonances with a $SU(2)_L\times SU(2)_R$ spectral global symmetry. This symmetry partially protects the electroweak S-parameter from large contributions of the vector resonances. The resulting custodial vector model spectrum and interactions with the standard model fields lead to distinct signatures at the LHC in the diboson, dilepton and associated Higgs channels.
Re-weighting at the LHC: the p–Pb data impact
2016
Abstract In this work we present selected results of a comprehensive analysis of the medium modifications in proton-lead LHC Run I data, and discuss the implications on different sets of nuclear parton densities. We find that the nuclear environment has a non-negligible relevance on the experimental results. We incorporate the information from Run I into the current nuclear densities and provide novel sets of nPDFs that will be useful for future predictions.