arXiv subjects

Ingrid McKibben Lofnes

Publications and source records attributed to Ingrid McKibben Lofnes.

3 recordsLinked to original sources

arXiv2025

Proceedngs of Charmonium production in heavy-ion collisions, Quark Matter 2025

The early production of heavy quarks ($c\bar{c}$ and $b\bar{b}$) makes charmonia an ideal probe to study the evolution of the hot and dense medium produced in ultra-relativistic heavy-ion collisions, known as the quark--gluon plasma (QGP). At LHC energies, the well established suppression of charmonium yield from color screening in the QGP is counterbalanced by the recombination of uncorrelated charm-quark pairs, either throughout the QGP phase or solely at the phase boundary. Systematic measurements of charmonium ground and excited states are important to discriminate between the scenarios forseen by various theoretical models. In addition, studies of non-prompt charmonia, i.e., charmonia originating from the decay of beauty hadrons, give access to study the energy loss of beauty quarks in the QGP. In these proceedings we present recently published Run 2 results by the ALICE Collaboration of prompt and non-prompt J/$ψ$ measured at midrapidity in Pb--Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV. In addition, the first preliminary Run 3 measurement of the $ψ$(2S)-to-J/$ψ$ ratio, measured at forward rapidity in Pb--Pb collisions at $\sqrt{s_{\rm NN}}$= 5.36 TeV, is shown. The results are compared to available theoretical model calculations.

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arXiv2021

Quarkonia as probes of the QGP and the initial stages of the heavy-ion collisions with ALICE

Studies of quarkonium production in heavy-ion collisions can be used for probing QGP properties. The suppression and regeneration of bound quarkonium states is sensitive to the medium properties. Modifications of the quarkonium polarization in Pb-Pb collisions with respect to pp collisions may give further insight into the suppression and regeneration mechanisms in the QGP. Quarkonia are also sensitive to the initial stages of heavy-ion collisions, and measurements in photonuclear collisions may help constrain the nuclear gluon-distribution at low Bjorken-$x$. In this work, recent quarkonium measurements performed by ALICE in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}~=~5.02$ TeV will be discussed. Preliminary measurements of the inclusive J/$ψ$ $R_{\rm AA}$ measured at both forward and midrapidity will be presented. The J/$ψ$ polarization measured for the first time in Pb-Pb collisions, as well as preliminary measurements of the coherent J/$ψ$ photoproduction cross section, will be discussed.

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arXiv2020

J/$ψ$ production measurements at mid-rapidity using the ALICE detector at the LHC

Charmonium production is highly sensitive to the hot and dense medium created in (ultra)-relativistic heavy-ion collisions, known as the Quark-Gluon Plasma (QGP). Measurements of the J/$ψ$ production serve as important tools for studying the properties of this medium. In addition to QGP effects, the J/$ψ$ production is modified by the presence of cold nuclear matter (CNM) effects such as shadowing or parton energy loss. These effects are studied in proton-nucleus collisions where no QGP formation is expected. In order to quantify how the J/$ψ$ production is modified by the medium, the vacuum production is modelled in proton-proton (pp) collisions and used as a reference for heavy-ion and proton-nucleus collisions. Measurements in pp collisions also serve as important tools for testing Quantum Chromodynamic (QCD) based models in both perturbative and non-perturbative regimes. The ALICE detector has the unique capability of measuring the J/$ψ$ at mid-rapidity through the di-electron channel down to zero transverse momentum. In this contribution a selection of the newest J/$ψ$ measurements at mid-rapidity performed by the ALICE Collaboration during the LHC Run 2 period will be discussed.

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