Dielectron production in central Pb-Pb collisions at root sNN=5.02 TeV

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21340%2F25%3A00389216" target="_blank" >RIV/68407700:21340/25:00389216 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1103/xl6m-vbqk" target="_blank" >https://doi.org/10.1103/xl6m-vbqk</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1103/xl6m-vbqk" target="_blank" >10.1103/xl6m-vbqk</a>

Result language

angličtina

Original language name

Dielectron production in central Pb-Pb collisions at root sNN=5.02 TeV

Original language description

The first measurement of the e(+) e(-) pair production at midrapidity and low invariant mass in central Pb-Pb collisions at root sNN = 5.02 TeV at the Large Hadron Collider is presented. The yield of e(+)e(-) pairs is compared with a cocktail of expected hadronic decay contributions in the invariant mass (m(ee)) and pair transverse momentum (p(T,ee)) ranges m(ee) < 3.5 GeV/c(2) and p(T, ee) < 8 GeV/c. For 0.18 < m(ee) < 0.5 GeV/c(2) the ratio of data to the cocktail of hadronic contributions amounts to 1.40 +/- 0.11 (stat.) +/- 0.23 (syst.) +/- 0.16 (cocktail) and 1.42 +/- 0.11 (stat.) +/- 0.23 (syst.)(+0.24) (-0.29) (cocktail), including or not including medium effects in the estimation of the heavy-flavor background, respectively. It is consistent with predictions from two different models for an additional contribution of thermal e(+)e(-) pairs from the hadronic and partonic phases. In the intermediate-mass range (1.2 < mee < 2.6 GeV/c(2)), the pair transverse impact parameter of the e(+)e(-) pairs (DCA(ee), where "DCA" denotes "distance of closest approach") is used for the first time in Pb-Pb collisions to separate displaced dielectrons from heavy-flavor hadron decays from a possible (thermal) contribution produced at the interaction point. The data are consistent with a suppression of e(+)e(-) pairs from cc and an additional prompt component. Finally, the first direct-photon measurement in the 10% most central Pb-Pb collisions at root sNN = 5.02 TeV is reported via the study of virtual direct photons in the transverse momentum range 1 < pT < 5 GeV/c. A model including prompt photons, as well as photons from the preequilibrium and fluid-dynamic phases, can reproduce the result, while being at the upper edge of the data uncertainties.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10303 - Particles and field physics

Project

<a href="/en/project/LM2023040" target="_blank" >LM2023040: Research infrastructure for experiments at CERN</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

PHYSICAL REVIEW C

ISSN

2469-9985

e-ISSN

2469-9993

Volume of the periodical

112

Issue of the periodical within the volume

5

Country of publishing house

US - UNITED STATES

Number of pages

27

Pages from-to

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UT code for WoS article

001641482600001

EID of the result in the Scopus database

2-s2.0-105027404158