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Evidence for light-by-light scattering and searches for axion-like particles in ultraperipheral PbPb collisions at sqrt(s[NN]) = 5.02 TeVстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 11 ноября 2019 г.
- Авторы: Baskakov A., Belyaev A.V., Boos E., Ershov A.A., Gribushin A., Katkov I., Khein L., Klyukhin V., Kodolova O., Lokhtin I., Lukina O., Miagkov I., Obraztsov S., Petrushanko S., Popov A.A., Savrin V., Snigirev A., Zhukov V.Yu, CMS Collaboration
- Журнал: Physics Letters B
- Том: 797
- Год издания: 2019
- Издательство: Elsevier BV
- Местоположение издательства: Netherlands
- Первая страница: 134826
- DOI: 10.1016/j.physletb.2019.134826
- Аннотация: Evidence for the light-by-light scattering process, γγ→γγ, in ultraperipheral PbPb collisions at a centre-of-mass energy per nucleon pair of 5.02 TeV is reported. The analysis is conducted using a data sample corresponding to an integrated luminosity of 390 μb−1 recorded by the CMS experiment at the LHC. Light-by-light scattering processes are selected in events with two photons exclusively produced, each with transverse energy EγT> 2 GeV, pseudorapidity |ηγ|< 2.4, diphoton invariant mass mγγ> 5 GeV, diphoton transverse momentum pγγT< 1 GeV, and diphoton acoplanarity below 0.01. After all selection criteria are applied, 14 events are observed, compared to expectations of 11.1 ± 1.1 (theo) events for the signal and 4.0 ± 1.2 (stat) for the background processes. The excess observed in data relative to the background-only expectation corresponds to a significance of 4.1 standard deviations, and has properties consistent with those expected for the light-by-light scattering signal. The measured fiducial light-by-light scattering cross section, σfid(γγ→γγ)= 120 ± 46 (stat) ± 28 (syst) ± 4 (theo) nb, is consistent with the standard model prediction. The mγγ distribution is used to set new exclusion limits on the production of pseudoscalar axion-like particles, via the γγ→ a →γγ process, in the mass range ma= 5-90 GeV.
- Добавил в систему: Лохтин Игорь Петрович