UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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2024-11-22 2:17
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Conference: Bucharest University Faculty of Physics 2021 Meeting


Section: Nuclear and Elementary Particles Physics


Title:
Soft Photon Study in Hadron and Nuclear Interactions


Authors:
Alexandra-Gabriela SERBAN (1), Elena KOKOULINA (2)


Affiliation:
1) University of Bucharest, Faculty of Physics, P.O.Box MG-11, Magurele, 077125 Bucharest, Romania

2) Joint Institute for Nuclear Research 6 Joliot-Curie St 141980 Dubna, Moscow region, Russia


E-mail
alexandra.serban4@s.unibuc.ro


Keywords:
soft photons, electromagnetic calorimeters, energy resolution


Abstract:
For over 30 years there has been no comprehensive understanding of the mechanism of soft photons formation. Soft photons (SPh) are the direct products of high energy interactions. They are not decay products of secondary particles and their energy is smaller than 50 MeV. Experimental data indicate an excess of their yield in hadron and nuclear interactions. The existing theoretical calculations based on the quantum electrodynamics can not predict and explain this excess. For a more thorough study of this phenomenon the building of the future accelerator complex NICA makes possible to carry out such studies in different interactions. Up to now the nature of SPh remains enigmatic. Apparently, they are formed in the region of non perturbative quantum chromodynamics and physicists build phenomenological models. The most successful model is based on the hypothesis of the cold quark-gluon plasma (QGP) formation. This model implies the formation of a quark-gluon system which consists of a few quarks, antiquarks and gluons (about 40 partons). These partons are encountering each other and reradiate soft photons because they do not have enough energy to produce hadrons, the main reactions being Compton scattering and pair annihilation.


References:

Elena Kokoulina, Nurlan Barlykov, Vladimir Dudin, Vladimir Dunin, Andrey Kutov, Vladimir Nikitin, Vasilii Riadovikov, Roman Shulyakovsky. Study of soft photon yield in pp and AA interactions at JINR. EPJ Web Conf. 235 03003 (2020).

C. Grupen and B. Shwartz. Particles detectors (Cambridge University Press, New York, 2011).

Acknowledgement:
I am thankful to Professor Elena Kokoulina who guided my steps in the understanding of calorimetry simulations using Geant4 and of analysis using CERN Root.