Multiple Parton Interactions with ALICE: from pp to p-Pb

The study of multiplicity dependent di-hadron angular correlations allows us to assess the contribution of multiple-parton interactions to particle production. We will review these measurements in pp and p-Pb collisions with the ALICE detector at the LHC and discuss the results in the context of centrality determination and other multiplicity dependent observables in p-Pb.Comment: 9 pages, 10 figures; Invited talk presented at the 30th Winter Workshop on Nuclear Dynamics (WWND 2014), Galveston, Texas, USA, April 6-12, 201

p-Pb Results from ALICE with an Emphasis on Centrality Determination

New ALICE results concerning particle production at low and intermediate transverse momenta in p-Pb collisions at a centre of mass energy of 5.02 TeV per nucleon pair are briefly discussed. Emphasis is given to the determination of centrality in p-Pb and their implications for binary scaling of hard processes.Comment: 5 pages, 5 figures, talk given at Strangeness in Quark Matter SQM 2013, 22nd - 27th July 2013 Birmingham, United Kingdo

Results on Jet Spectra and Structure from ALICE

Full jet reconstruction in ALICE uses the combined information from charged and neutral particles. Essentially all jet constituents can be measured with large efficiency down to very low transverse momenta (pT > 150 MeV/c). This has the advantage to introduce a minimum bias on the jet fragmentation, in particular for low jet momenta and in the presence of quenching. In this article, we present preliminary results from reconstruction of charged jets in Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV. The inclusive charged jet spectrum, the jet nuclear modification factors (R_AA, R_CP), the ratio of spectra measured with different resolution parameters and hadron-jet correlations are discussed. For pp data at the same center of mass energy, the inclusive spectrum of fully reconstructed jets and its resolution parameter dependence are reported.Comment: 8 pages, 11 figures; to be published in the Proceedings of Quark Matter 201

Absence of jet quenching in peripheral nucleus-nucleus collisions

Medium effects on the production of high-$p_{\rm T}$ particles in nucleus-nucleus (AA) collisions are generally quantified by the nuclear modification factor ($R_{\rm AA}$), defined to be unity in absence of nuclear effects. Modeling particle production including a nucleon-nucleon impact parameter dependence, we demonstrate that $R_{\rm AA}$ at midrapidity in peripheral AA collisions can be significantly affected by event selection and geometry biases. Even without jet quenching and shadowing, these biases cause an apparent suppression for $R_{\rm AA}$ in peripheral collisions, and are relevant for all types of hard probes and all collision energies. Our studies indicate that calculations of jet quenching in peripheral AA collisions should account for the biases, or else they will overestimate the relevance of parton energy loss. Similarly, expectations of parton energy loss in light-heavy collision systems based on comparison with apparent suppression seen in peripheral $R_{\rm AA}$ should be revised. Our interpretation of the peripheral $R_{\rm AA}$ data would unify observations for lighter collision systems or lower energies where significant values of elliptic flow are observed despite the absence of strong jet quenching.Comment: 13 pages, 4 captioned figures (the 4th is not in the published version); our code for HG-PYTHIA was ported in 2019 by Austin Baty to run on top of a default PYTHIA installation and can be found at https://github.com/abaty/HGPythi

ALICE Simulation Framework

Proposal of abstract for CHEP2000ALICE uses an object oriented framework for simulation and reconstruction based on ROOT (AliRoot).Here, we describe those components of the class design that represent common concepts of simulation, such as particle generation and transport, detector response and detector segmentation. Applications for fast and slow physics and detector performance simulations as well as the relevance of the design for visualisation and the link of simulation to reconstruction are discussed

Radiation Studies for the ALICE Environment Using FLUKA and ALIFE

The ALIFE editor and parser for FLUKA geometries and input options is presented. The capabilities of ALIFE are demonstrated by radiation studies for the environment of the ALICE experiment at LHC. These studies cover beam-loss situations and induced radioactivity in the low-b insertions

Possibility of Measuring Azimuthal Anisotropy in J/ψJ/\psi Absorption in the ALICE Experiment

The absorption of J/ψ by comovers in the forward rapidity region is predicted to be azimuthally anisotropic as compared to an isotropic Glauber absorption. In the framework of a fast simulation we investigate the possibility of measuring this anisotropy within the ALICE experiment for the J/ψ 's detected in the Di-Muon Spectrometer using the event plane provided by the Photon Multiplicity Detector(PMD). The effect of limitations in the event plane determination on measured J/ψ anisotropy is also investigated

Jet-like near-side peak shapes in Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV with ALICE

We present preliminary results from di-hadron correlations in azimuth (phi) and pseudo-rapidity (eta) induced by hadronic di-jets produced in Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV. The jet-like near-side peak has been isolated from eta-independent collective flow correlations using an eta-gap method and its shape has been characterized by rms and excess kurtosis. These quantities have been studied as a function of centrality as well as of trigger (associated) particle transverse momentum ranging from 2-8 GeV (1-3 GeV). We observe that the rms in Deta increases with the centrality of the collisions whereas the rms in Dphi stays constant within experimental uncertainties.Comment: 4 pages, 4 figures, Proceedings for Hard Probes 201