Challenges of direct photon production at forward rapidities and large p(T)

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21340%2F17%3A00311855" target="_blank" >RIV/68407700:21340/17:00311855 - isvavai.cz</a>

Výsledek na webu

<a href="http://iopscience.iop.org/article/10.1088/1742-6596/805/1/012003/pdf" target="_blank" >http://iopscience.iop.org/article/10.1088/1742-6596/805/1/012003/pdf</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/1742-6596/805/1/012003" target="_blank" >10.1088/1742-6596/805/1/012003</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Challenges of direct photon production at forward rapidities and large p(T)

Popis výsledku v původním jazyce

Direct photons produced in interactions with nuclear targets represent a cleaner probe for investigation of nuclear effects than hadrons, since photons have no final state interaction and no energy loss or absorption is expected in the produced hot medium. Therefore, besides the Cronin enhancement at medium-high transverse momenta p(T) and isospin effects at larger p(T), one should not expect any nuclear effects. However, this fact is in contrast to the PHENIX data providing an evidence for a significant large-p(T) suppression at mid rapidities in central d + Au and Au + Au collisions that cannot be induced by coherent phenomena (gluon shadowing, Color Glass Condensate). We demonstrate that such an unexpected results is subject to deficit of energy induced universally by multiple initial state interactions (ISI) towards the kinematic limits (large Feynman x(F) and/or large x(T) = 2p(T) / root s). For this reason, in order to enhance the effects of coherence, one should be cautious going to forward rapidities and higher energies. In the LHC kinematic region ISI corrections are irrelevant at mid rapidities but cause rather strong suppression at forward rapidities and large p(T). Numerical calculations of invariant p(T) spectra and the nuclear modification factor were performed within two different models, the color dipole formalism and the model based on k(T)-factorization, which are successfully confronted with available data from the RHIC and LHC collider experiments. Finally, we perform also predictions for a strong onset of ISI corrections at forward rapidities and corresponding expected suppression can be verified by the future measurements at LHC.

Název v anglickém jazyce

Challenges of direct photon production at forward rapidities and large p(T)

Popis výsledku anglicky

Direct photons produced in interactions with nuclear targets represent a cleaner probe for investigation of nuclear effects than hadrons, since photons have no final state interaction and no energy loss or absorption is expected in the produced hot medium. Therefore, besides the Cronin enhancement at medium-high transverse momenta p(T) and isospin effects at larger p(T), one should not expect any nuclear effects. However, this fact is in contrast to the PHENIX data providing an evidence for a significant large-p(T) suppression at mid rapidities in central d + Au and Au + Au collisions that cannot be induced by coherent phenomena (gluon shadowing, Color Glass Condensate). We demonstrate that such an unexpected results is subject to deficit of energy induced universally by multiple initial state interactions (ISI) towards the kinematic limits (large Feynman x(F) and/or large x(T) = 2p(T) / root s). For this reason, in order to enhance the effects of coherence, one should be cautious going to forward rapidities and higher energies. In the LHC kinematic region ISI corrections are irrelevant at mid rapidities but cause rather strong suppression at forward rapidities and large p(T). Numerical calculations of invariant p(T) spectra and the nuclear modification factor were performed within two different models, the color dipole formalism and the model based on k(T)-factorization, which are successfully confronted with available data from the RHIC and LHC collider experiments. Finally, we perform also predictions for a strong onset of ISI corrections at forward rapidities and corresponding expected suppression can be verified by the future measurements at LHC.

Druh

D - Stať ve sborníku

CEP obor

—

OECD FORD obor

10303 - Particles and field physics

Projekt

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

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2017

Kód důvěrnosti údajů

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

Název statě ve sborníku

Journal of Physics Conference Series

ISBN

—

ISSN

1742-6588

e-ISSN

—

Počet stran výsledku

9

Strana od-do

—

Název nakladatele

IOP Publishing Ltd.

Místo vydání

Bristol

Místo konání akce

SUBATECH, Nantes

Datum konání akce

9. 9. 2014

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

000400394800003