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A search for Z bosons in the μ(+)μ(-) decay channel has been performed in PbPb collisions at √S(NN)=2.76 TeV with the CMS detector at the LHC, in a 7.2 μb(-1) data sample. The number of opposite-sign muon pairs observed in the 60-120 GeV/c(2) invariant mass range is 39, corresponding to a yield per unit of rapidity (y) and per minimum bias event of [33.8±5.5(stat)±4.4(syst)]×10(-8), in the |y|<2.0 range. Rapidity, transverse momentum, and centrality dependencies are also measured. The results agree with next-to-leading order QCD calculations, scaled by the number of incoherent nucleon-nucleon collisions.
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http://dx.doi.org/10.1103/PhysRevLett.106.212301 | DOI Listing |
Charged hadron elliptic anisotropies (v_{2}) are presented over a wide transverse momentum (p_{T}) range for proton-lead (pPb) and lead-lead (PbPb) collisions at nucleon-nucleon center-of-mass energies of 8.16 and 5.02 TeV, respectively.
View Article and Find Full Text PDFPhys Rev Lett
July 2025
INFN, Sezione di Pavia, Pavia, Italy.
The ALICE Collaboration reports measurements of the large relative transverse momentum (k_{T}) component of jet substructure in pp and Pb-Pb collisions at center-of-mass energy per nucleon pair sqrt[s_{NN}]=5.02 TeV. Enhancement in the yield of such large-k_{T} emissions in head-on Pb-Pb collisions is predicted to arise from partonic scattering with quasiparticles of the quark-gluon plasma.
View Article and Find Full Text PDFPhys Rev Lett
April 2025
INFN, Sezione di Pavia, Pavia, Italy.
In this Letter, the first evidence of the _{Λ[over ¯]}^{4}He[over ¯] antihypernucleus is presented, along with the first measurement at the LHC of the production of (anti)hypernuclei with mass number A=4, specifically (anti)_{Λ}^{4}H and (anti)_{Λ}^{4}He. In addition, the antiparticle-to-particle ratios for both hypernuclei (_{Λ[over ¯]}^{4}H[over ¯]/_{Λ}^{4}H and _{Λ[over ¯]}^{4}He[over ¯]/_{Λ}^{4}He) are shown, which are sensitive to the baryochemical potential of the strongly interacting matter created in heavy-ion collisions. The results are obtained from a data sample of central Pb-Pb collisions, collected during the 2018 LHC data taking at a center-of-mass energy per nucleon pair of sqrt[s_{NN}]=5.
View Article and Find Full Text PDFPhys Rev Lett
January 2025
INFN, Sezione di Pavia, Pavia, Italy.
This Letter presents the first measurement of event-by-event fluctuations of the net number (difference between the particle and antiparticle multiplicities) of multistrange hadrons Ξ^{-} and Ξ[over ¯]^{+} and its correlation with the net-kaon number using the data collected by the ALICE Collaboration in pp, p-Pb, and Pb-Pb collisions at a center-of-mass energy per nucleon pair sqrt[s_{NN}]=5.02 TeV. The statistical hadronization model with a correlation over three units of rapidity between hadrons having the same and opposite strangeness content successfully describes the results.
View Article and Find Full Text PDFEur Phys J C Part Fields
December 2024
Department of Physics and Astronomy, University College London, London, WC1E 6BT UK.