A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Soft-Dielectron Excess in Proton-Proton Collisions at √s = 13 TeV (2021)

ALICE Collaboration. (2021). Soft-Dielectron Excess in Proton-Proton Collisions at √s = 13 TeV. Physical Review Letters, 127(4), Article 042302. https://doi.org/10.1103/PhysRevLett.127.042302

JYU-tekijät tai -toimittajat

Julkaisun tiedot

Julkaisun kaikki tekijät tai toimittajat: ALICE Collaboration

Lehti tai sarja: Physical Review Letters

ISSN: 0031-9007

eISSN: 1079-7114

Julkaisuvuosi: 2021

Volyymi: 127

Lehden numero: 4

Artikkelinumero: 042302

Kustantaja: American Physical Society

Julkaisumaa: Yhdysvallat (USA)

Julkaisun kieli: englanti

DOI: https://doi.org/10.1103/PhysRevLett.127.042302

Julkaisun avoin saatavuus: Avoimesti saatavilla

Julkaisukanavan avoin saatavuus: Osittain avoin julkaisukanava

Julkaisu on rinnakkaistallennettu (JYX): https://jyx.jyu.fi/handle/123456789/77414

Julkaisu on rinnakkaistallennettu: https://arxiv.org/abs/2005.14522

Tiivistelmä

A measurement of dielectron production in proton-proton (pp) collisions at √s=13 TeV, recorded with the ALICE detector at the CERN LHC, is presented in this Letter. The data set was recorded with a reduced magnetic solenoid field. This enables the investigation of a kinematic domain at low dielectron (ee) invariant mass mee and pair transverse momentum pT,ee that was previously inaccessible at the LHC. The cross section for dielectron production is studied as a function of mee, pT,ee, and event multiplicity dNch/dη. The expected dielectron rate from hadron decays, called hadronic cocktail, utilizes a parametrization of the measured η/π0 ratio in pp and proton-nucleus collisions, assuming that this ratio shows no strong dependence on collision energy at low transverse momentum. Comparison of the measured dielectron yield to the hadronic cocktail at 0.15<0.6 GeV/c2 and for pT,ee<0.4 GeV/c indicates an enhancement of soft dielectrons, reminiscent of the “anomalous” soft-photon and soft-dilepton excess in hadron-hadron collisions reported by several experiments under different experimental conditions. The enhancement factor over the hadronic cocktail amounts to 1.61±0.13(stat)±0.17(syst,data)±0.34(syst,cocktail) in the ALICE acceptance. Acceptance-corrected excess spectra in mee and pT,ee are extracted and compared with calculations of dielectron production from hadronic bremsstrahlung and thermal radiation within a hadronic many-body approach.

YSO-asiasanat: hiukkasfysiikka

Liittyvät organisaatiot

OKM-raportointi: Kyllä

Raportointivuosi: 2021

JUFO-taso: 3