119,330 research outputs found
Performance of prototypes for the ALICE electromagnetic calorimeter
No full textThe performance of prototypes for the ALICE electromagnetic sampling
calorimeter has been studied in test beam measurements at FNAL and CERN. A
array of final design modules showed an energy resolution of about
11% / 1.7 % with a uniformity of the response
to electrons of 1% and a good linearity in the energy range from 10 to 100 GeV.
The electromagnetic shower position resolution was found to be described by 1.5
mm 5.3 mm /. For an electron identification
efficiency of 90% a hadron rejection factor of >600 was obtained
Searching for the dead cone effects with iterative declustering of heavy-flavor jets
No full textWe present a new method to expose the dead-cone effect at colliders using iterative declustering techniques. Iterative declustering allows one to unwind the jet clustering and to access the subjets or branches at different depths of the jet tree. Our method consists of declustering the heavy flavor-tagged jet using the Cambridge-Achen algorithm following the branch containing the heavy flavor at each step and registering the kinematics of the complementary untagged prong. The kinematics of the complementary untagged prong fill a Lund map representing the gluon radiation off the heavy-flavor quark at each step of the vacuum shower. Using Pythia8 Monte Carlo, we show that a simple cut on the Lund plane introduced by ln(kT)>0 suppresses hadronization effects and the angular separation between the jet prongs becomes very sensitive to flavor effects. A clear suppression for heavy-flavor jets relative to inclusive jets in the region of splitting angles delimited by the relation
Studying the QGP with Jets at the LHC and RHIC
No full textWe review the current status of jet measurements in heavy-ion collisions at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC). We discuss how the current measurements provide information about the quark-gluon plasma and discuss near future opportunities at both RHIC and the LHC
Implementation of a medium-modified parton shower algorithm
No full textWe present a Monte Carlo implementation of medium-induced gluon radiation in the final-state branching process. Medium effects are introduced through an additive term in the splitting functions. We have implemented such modification within PYTHIA. We show the medium effects on the hump-backed plateau, and the transverse-momentum and angular distributions with respect to the parent parton. As expected, with increasing medium densities there is an increase (decrease) of partons with small (large) momentum fraction, and angular broadening is observed. The effects on the transverse-momentum distributions are more involved, with an enhancement of low- and intermediate-p T partons and a decrease at large p T, which is related to energy conservation, and to the lack of momentum exchange with the medium in our approach
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Angular-ordered parton shower with medium-modified splitting functions
No full textModified Altarelli-Parisi splitting functions were recently proposed to model multi-parton radiation in a dense medium and describe jet quenching, one of the most striking features of heavy-ion collisions. We implement medium-modified splitting functions in the HERWIG parton shower algorithm, which satisfies the angular ordering prescription, and present a few parton-level results, such as transverse momentum, angle and energy-fraction distributions, which exhibit remarkable medium-induced effects. We also comment on the comparison with respect to the results yielded by other implementations of medium-modified splitting functions in the framework of virtuality-ordered parton cascade
Multiplicity associated to high pT events and multiplicity fluctuations
No full textIt is shown that the difference between the multiplicity associated to high pT events and the unbiased multiplicity is given by the normalized variance of the multiplicity distribution, as a consequence of high pT events being self-shadowed. We discuss the possibility of checking the nonmonotonic behavior with centrality of the normalized variance by measuring the difference between multiplicities
Medium evolved fragmentation functions
No full textMedium-induced gluon radiation is usually identified as the dominant dynam-
ical mechanism underling the jet quenching phenomenon observed in heavy-ion collisions.
In its actual implementation, multiple medium-induced gluon emissions are assumed to be
independent, leading, in the eikonal approximation, to a Poisson distribution. Here, we
introduce a medium term in the splitting probabilities so that both medium and vacuum
contributions are included on the same footing in a DGLAP approach. The improvements
include energy-momentum conservation at each individual splitting, medium-modified vir-
tuality evolution and a coherent implementation of vacuum and medium splitting proba-
bilities. Noticeably, the usual formalism is recovered when the virtuality and the energy of
the parton are very large. This leads to a similar description of the suppression observed
in heavy-ion collisions with values of the transport coefficient of the same order as those
obtained using the quenching weight
Nuclear-like effects in proton-proton collisions at high energy
No full textWe show that several effects considered nuclear effects are not nuclear in the sense that they do not only occur in nucleus–nucleus and hadron–nucleus collisions but, as well, they are present in hadron–hadron (proton–proton) collisions. The matter creation mechanism in hh, hA and AA collision is always the same. The p T suppression of particles produced in large multiplicity events compared to low multiplicity events, the elliptic flow and the Cronin effect are predicted to occur in pp collisions at LHC energies as a consequence of the high density partonic medium obtained
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
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