Production of Cumulative Pions and Percolation of Strings

Production of pions in high-energy collisions with nuclei in the kinematics prohibited for free nucleons (“cumulative pions”) is studied in the fusing color string model. The model describes the so-called direct mechanism for cumulative production. The other (spectator) mechanism dominates in produc...

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Main Author: Mikhail Aleksandrovich Braun
Format: Article
Language:English
Published: MDPI AG 2023-04-01
Series:Universe
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Online Access:https://www.mdpi.com/2218-1997/9/4/195
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author Mikhail Aleksandrovich Braun
author_facet Mikhail Aleksandrovich Braun
author_sort Mikhail Aleksandrovich Braun
collection DOAJ
description Production of pions in high-energy collisions with nuclei in the kinematics prohibited for free nucleons (“cumulative pions”) is studied in the fusing color string model. The model describes the so-called direct mechanism for cumulative production. The other (spectator) mechanism dominates in production of cumulative protons, and is suppressed for pions. In the model, cumulative pions are generated by string fusion, which raises the maximal energy of produced partons above the level of the free nucleon kinematics. Momentum and multiplicity sum rules are used to determine the spectra in the deep fragmentation region. Predicted spectra of cumulative pions exponentially fall with the scaling variable <i>x</i> in the interval <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo><</mo><mi>x</mi><mo><</mo><mn>3</mn></mrow></semantics></math></inline-formula> with a slope between 5.1 and 5.6, which agrees well with the raw data obtained in the recent experiment at RHIC involving Cu–Au collisioins. However, the agreement is worse for the so-called unfolded data, presumably taking into account corrections due to the experimental setup and having rather a power-like form.
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spelling doaj.art-204c5317e1fc4cdeb1d9fc04f7d321822023-11-17T21:40:36ZengMDPI AGUniverse2218-19972023-04-019419510.3390/universe9040195Production of Cumulative Pions and Percolation of StringsMikhail Aleksandrovich Braun0Department of High Energy Physics, University of S. Petersburg, 198904 St. Petersburg, RussiaProduction of pions in high-energy collisions with nuclei in the kinematics prohibited for free nucleons (“cumulative pions”) is studied in the fusing color string model. The model describes the so-called direct mechanism for cumulative production. The other (spectator) mechanism dominates in production of cumulative protons, and is suppressed for pions. In the model, cumulative pions are generated by string fusion, which raises the maximal energy of produced partons above the level of the free nucleon kinematics. Momentum and multiplicity sum rules are used to determine the spectra in the deep fragmentation region. Predicted spectra of cumulative pions exponentially fall with the scaling variable <i>x</i> in the interval <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo><</mo><mi>x</mi><mo><</mo><mn>3</mn></mrow></semantics></math></inline-formula> with a slope between 5.1 and 5.6, which agrees well with the raw data obtained in the recent experiment at RHIC involving Cu–Au collisioins. However, the agreement is worse for the so-called unfolded data, presumably taking into account corrections due to the experimental setup and having rather a power-like form.https://www.mdpi.com/2218-1997/9/4/195heavy ionshih-energy collisionscolor stringscumulative particles
spellingShingle Mikhail Aleksandrovich Braun
Production of Cumulative Pions and Percolation of Strings
Universe
heavy ions
hih-energy collisions
color strings
cumulative particles
title Production of Cumulative Pions and Percolation of Strings
title_full Production of Cumulative Pions and Percolation of Strings
title_fullStr Production of Cumulative Pions and Percolation of Strings
title_full_unstemmed Production of Cumulative Pions and Percolation of Strings
title_short Production of Cumulative Pions and Percolation of Strings
title_sort production of cumulative pions and percolation of strings
topic heavy ions
hih-energy collisions
color strings
cumulative particles
url https://www.mdpi.com/2218-1997/9/4/195
work_keys_str_mv AT mikhailaleksandrovichbraun productionofcumulativepionsandpercolationofstrings