Measurement of transverse single-spin asymmetries of pi(0) and electromagnetic jets at forward rapidity in 200 and 500 GeV transversely polarized proton-proton collisions

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389005%3A_____%2F21%3A00543904" target="_blank" >RIV/61389005:_____/21:00543904 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/68407700:21340/21:00351231

Výsledek na webu

<a href="https://doi.org/10.1103/PhysRevD.103.092009" target="_blank" >https://doi.org/10.1103/PhysRevD.103.092009</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1103/PhysRevD.103.092009" target="_blank" >10.1103/PhysRevD.103.092009</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Measurement of transverse single-spin asymmetries of pi(0) and electromagnetic jets at forward rapidity in 200 and 500 GeV transversely polarized proton-proton collisions

Popis výsledku v původním jazyce

The STAR Collaboration reports measurements of the transverse single-spin asymmetry (TSSA) of inclusive pi(0) at center-of-mass energies (root s) of 200 GeV and 500 GeV in transversely polarized proton-proton collisions in the pseudo-rapidity region 2.7 to 4.0. The results at the two different energies show a continuous increase of the TSSA with Feynman-x, and, when compared to previous measurements, no dependence on root s from 19.4 GeV to 500 GeV is found. To investigate the underlying physics leading to this large TSSA, different topologies have been studied. pi(0) with no nearby particles tend to have a higher TSSA than inclusive pi(0). The TSSA for inclusive electromagnetic jets, sensitive to the Sivers effect in the initial state, is substantially smaller, but shows the same behavior as the inclusive pi(0) asymmetry as a function of Feynman-x. To investigate final-state effects, the Collins asymmetry of pi(0) inside electromagnetic jets has been measured. The Collins asymmetry is analyzed for its dependence on the pi(0) momentum transverse to the jet thrust axis and its dependence on the fraction of jet energy carried by the pi(0). The asymmetry was found to be small in each case for both center-of-mass energies. All the measurements are compared to QCD-based theoretical calculations for transverse-momentum-dependent parton distribution functions and fragmentation functions. Some discrepancies are found, which indicates new mechanisms might be involved.

Název v anglickém jazyce

Measurement of transverse single-spin asymmetries of pi(0) and electromagnetic jets at forward rapidity in 200 and 500 GeV transversely polarized proton-proton collisions

Popis výsledku anglicky

The STAR Collaboration reports measurements of the transverse single-spin asymmetry (TSSA) of inclusive pi(0) at center-of-mass energies (root s) of 200 GeV and 500 GeV in transversely polarized proton-proton collisions in the pseudo-rapidity region 2.7 to 4.0. The results at the two different energies show a continuous increase of the TSSA with Feynman-x, and, when compared to previous measurements, no dependence on root s from 19.4 GeV to 500 GeV is found. To investigate the underlying physics leading to this large TSSA, different topologies have been studied. pi(0) with no nearby particles tend to have a higher TSSA than inclusive pi(0). The TSSA for inclusive electromagnetic jets, sensitive to the Sivers effect in the initial state, is substantially smaller, but shows the same behavior as the inclusive pi(0) asymmetry as a function of Feynman-x. To investigate final-state effects, the Collins asymmetry of pi(0) inside electromagnetic jets has been measured. The Collins asymmetry is analyzed for its dependence on the pi(0) momentum transverse to the jet thrust axis and its dependence on the fraction of jet energy carried by the pi(0). The asymmetry was found to be small in each case for both center-of-mass energies. All the measurements are compared to QCD-based theoretical calculations for transverse-momentum-dependent parton distribution functions and fragmentation functions. Some discrepancies are found, which indicates new mechanisms might be involved.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10303 - Particles and field physics

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2021

Kód důvěrnosti údajů

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

Název periodika

Physical Review D

ISSN

2470-0010

e-ISSN

2470-0029

Svazek periodika

103

Číslo periodika v rámci svazku

9

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

14

Strana od-do

092009

Kód UT WoS článku

000655872600001

EID výsledku v databázi Scopus

2-s2.0-85107301897