1,816 research outputs found
Measurement of the production of high-p(T) electrons from heavy-flavour hadron decays in Pb-Pb collisions at root s(NN)=2.76 TeV
No full textElectrons from heavy-flavour hadron decays (charm and beauty) were measured with the ALICE detector in Pb-Pb collisions at a centre-of-mass of energy root s(NN) = 2.76 TeV. The transverse momentum (pT) differential production yields at mid-rapidity were used to calculate the nuclear modification factor R-AA in the interval 3 < p(T) < 18 GeV/c. The R-AA shows a strong suppression compared to binary scaling of pp collisions at the same energy (up to a factor of 4) in the 10% most central Pb-Pb collisions. There is a centrality trend of suppression, and a weaker suppression (down to a factor of 2) in semi-peripheral (50-80%) collisions is observed. The suppression of electrons in this broad p(T) interval indicates that both charm and beauty quarks lose energy when they traverse the hot medium formed in Pb-Pb collisions at LHC. (C) 2017 The Author. Published by Elsevier B.V
Publisher Correction: Unveiling the strong interaction among hadrons at the LHC (Nature, (2020), 588, 7837, (232-238), 10.1038/s41586-020-3001-6)
No full textIn Fig. 1c of this Article, owing to an error during the production process, the equation incorrectly began ‘C(k*, r*) = …’ instead of ‘C(k*) = …’. In addition, in affiliation 71 ‘Dipartimento di Fisica dell’Università degli studi di Bari Aldo Moro’ has been corrected to read ‘Dipartimento di Fisica dell’Università degli studi di Cagliari’. The original Article has been corrected online. *A list of authors and their affiliations appears online. © 2021, The Author(s), under exclusive licence to Springer Nature Limited
Production of pions, kaons, and protons as a function of the relative transverse activity classifier in pp collisions at √s = 13 TeV
No full textThe production of π ±, K±, and (p ̄) p is measured in pp collisions at s = 13 TeV in different topological regions of the events. Particle transverse momentum (p T) spectra are measured in the “toward”, “transverse”, and “away” angular regions defined with respect to the direction of the leading particle in the event. While the toward and away regions contain the fragmentation products of the near-side and away-side jets, respectively, the transverse region is dominated by particles from the Underlying Event (UE). The relative transverse activity classifier, R T = N T/〈N T〉, is used to group events according to their UE activity, where N T is the measured charged-particle multiplicity per event in the transverse region and 〈N T〉 is the mean value over all the analysed events. The first measurements of identified particle p T spectra as a function of R T in the three topological regions are reported. It is found that the yield of high transverse momentum particles relative to the R T-integrated measurement decreases with increasing R T in both the toward and the away regions, indicating that the softer UE dominates particle production as R T increases and validating that R T can be used to control the magnitude of the UE. Conversely, the spectral shapes in the transverse region harden significantly with increasing R T. This hardening follows a mass ordering, being more significant for heavier particles. Finally, it is observed that the p T-differential particle ratios (p+p ̄)/(π++π−) and (K+ + K−)/(π + + π −) in the low UE limit (R T → 0) approach expectations from Monte Carlo generators such as PYTHIA 8 with Monash 2013 tune and EPOS LHC, where the jet-fragmentation models have been tuned to reproduce e+e− results. [Figure not available: see fulltext.
Measurements of inclusive jet spectra in pp and central Pb-Pb collisions at root S-NN=5.02 TeV
No full textThis article reports measurements of the p(T)-differential inclusive jet cross section in pp collisions at root S = 5.02 TeV and the p(T)-differential inclusive jet yield in Pb-Pb 0-10% central collisions at root S-NN = 5.02 TeV. Jets were reconstructed at midrapidity with the ALICE tracking detectors and electromagnetic calorimeter using the anti-k(T) algorithm. For pp collisions, we report jet cross sections for jet resolution parameters R = 0.1-0.6 over the range 20 < p(T,jet) < 140 GeV/c, as well as the jet cross-section ratios of different R and comparisons to two next-to-leading-order (NLO)-based theoretical predictions. For Pb-Pb collisions, we report the R = 0.2 and R = 0.4 jet spectra for 40 < p(T,jet) < 140 GeV/c and 60 < p(T,jet) < 140 GeV/c, respectively. The scaled ratio of jet yields observed in Pb-Pb to pp collisions, R-AA, is constructed, and exhibits strong jet quenching and a clear p(T) dependence for R = 0.2. No significant R dependence of the jet R-AA is observed within the uncertainties of the measurement. These results are compared to several theoretical predictions
Measurement of inclusive and leading subjet fragmentation in pp and Pb–Pb collisions at s NN = 5.02 TeV
No full textAbstract This article presents new measurements of the fragmentation properties of jets in both proton–proton (pp) and heavy-ion collisions with the ALICE experiment at the Large Hadron Collider (LHC). We report distributions of the fraction z r of transverse momentum carried by subjets of radius r within jets of radius R. Charged-particle jets are reconstructed at midrapidity using the anti-k T algorithm with jet radius R = 0.4, and subjets are reconstructed by reclustering the jet constituents using the anti-k T algorithm with radii r = 0.1 and r = 0.2. In proton–proton collisions, we measure both the inclusive and leading subjet distributions. We compare these measurements to perturbative calculations at next-to-leading logarithmic accuracy, which suggest a large impact of threshold resummation and hadronization effects on the z r distribution. In heavy-ion collisions, we measure the leading subjet distributions, which allow access to a region of harder jet frag- mentation than has been probed by previous measurements of jet quenching via hadron fragmentation distributions. The z r distributions enable extraction of the parton-to-subjet fragmentation function and allow for tests of the universality of jet fragmentation functions in the quark–gluon plasma (QGP). We find no significant modification of z r distributions in Pb–Pb compared to pp collisions. However, the distributions are also consistent with a hardening trend for z r < 0.95, as predicted by several jet quenching models. As z r → 1 our results indicate that any such hardening effects cease, exposing qualitatively new possibilities to disentangle competing jet quenching mechanisms. By comparing our results to theoretical calculations based on an independent extraction of the parton-to-jet fragmentation function, we find consistency with the universality of jet fragmentation and no indication of factorization breaking in the QGP
Measurement of charged jet suppression in Pb-Pb collisions at =2.76TeV
No full textA measurement of the transverse momentum spectra of jets in Pb-Pb collisions at =2.76TeV is reported. Jets are reconstructed from charged particles using the anti- jet algorithm with jet resolution parameters R of 0.2 and 0.3 in pseudo-rapidity ||<0.5. The transverse momentum p_T of charged particles is measured down to 0.15 GeV/c which gives access to the low p_T fragments of the jet. Jets found in heavy-ion collisions are corrected event-by-event for average background density and on an inclusive basis (via unfolding) for residual background fluctuations and detector effects. A strong suppression of jet production in central events with respect to peripheral events is observed. The suppression is found to be similar to the suppression of charged hadrons, which suggests that substantial energy is radiated at angles larger than the jet resolution parameter R=0.3 considered in the analysis. The fragmentation bias introduced by selecting jets with a high p_T leading particle, which rejects jets with a soft fragmentation pattern, has a similar effect on the jet yield for central and peripheral events. The ratio of jet spectra with R=0.2 and R=0.3 is found to be similar in Pb-Pb and simulated PYTHIA pp events, indicating no strong broadening of the radial jet structure in the reconstructed jets with R<0.3.A measurement of the transverse momentum spectra of jets in Pb-Pb collisions at TeV is reported. Jets are reconstructed from charged particles using the anti- jet algorithm with jet resolution parameters of and in pseudo-rapidity . The transverse momentum of charged particles is measured down to GeV/ which gives access to the low fragments of the jet. Jets found in heavy-ion collisions are corrected event-by-event for average background density and on an inclusive basis (via unfolding) for residual background fluctuations and detector effects. A strong suppression of jet production in central events with respect to peripheral events is observed. The suppression is found to be similar to the suppression of charged hadrons, which suggests that substantial energy is radiated at angles larger than the jet resolution parameter considered in the analysis. The fragmentation bias introduced by selecting jets with a high leading particle, which rejects jets with a soft fragmentation pattern, has a similar effect on the jet yield for central and peripheral events. The ratio of jet spectra with and is found to be similar in Pb-Pb and simulated PYTHIA pp events, indicating no strong broadening of the radial jet structure in the reconstructed jets with
Powerful eximer laser systems with γ-pumping for plasma physics and ICF research in the 0.1- to 1.0-MJ energy range
No full textMeasurements of inclusive jet spectra in pp and central Pb-Pb collisions at root S-NN=5.02 TeV
No full textThis article reports measurements of the pT-differential inclusive jet cross section in pp collisions at s=5.02TeV and the pT-differential inclusive jet yield in Pb-Pb 0-10% central collisions at sNN=5.02TeV. Jets were reconstructed at midrapidity with the ALICE tracking detectors and electromagnetic calorimeter using the anti-kT algorithm. For pp collisions, we report jet cross sections for jet resolution parameters R=0.1-0.6 over the range 20<140 GeV/c, as well as the jet cross-section ratios of different R and comparisons to two next-to-leading-order (NLO)-based theoretical predictions. For Pb-Pb collisions, we report the R=0.2 and R=0.4 jet spectra for 40<140 GeV/c and 60<140 GeV/c, respectively. The scaled ratio of jet yields observed in Pb-Pb to pp collisions, RAA, is constructed, and exhibits strong jet quenching and a clear pT dependence for R=0.2. No significant R dependence of the jet RAA is observed within the uncertainties of the measurement. These results are compared to several theoretical predictions
Imaging diagnostic methods for identification of sentinel lymph nodes in patients with early squamous cell carcinoma of the oral cavity mucosa: a literature review
No full textPublisher Correction: Direct observation of the dead-cone effect in quantum chromodynamics (Nature, (2022), 605, 7910, (440-446), 10.1038/s41586-022-04572-w)
No full textIn the version of this article initially published, there was a typographical error in the first sentence following the “Exposing the dead cone” heading, now reading, “The measurements of R(θ), in the three radiator (charmquark) energy intervals 5 &lt; ERadiator &lt; 10 GeV, 10 &lt; ERadiator &lt; 20 GeV and 20 &lt; ERadiator &lt; 35 GeV…,” where “35 GeV” initially appeared as “3 GeV.” The error has been corrected in the HTML and PDF versions of the article. *A list of authors and their affiliations appears online. © The Author(s) 2022
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