Geometrical scaling of prompt photons in heavy ion collisions

Praszałowicz, Michał

doi:10.1051/epjconf/201920602002

Cited by 7 publications

(11 citation statements)

References 31 publications

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“…That limit occurs, for instance, at central rapidities, x 1 = x 2 = p T / √ s. This scaling function closely resembles the universal multiplicity scaling for prompt photons investigated in Refs. [66][67][68], in which photon p T -spectra at low transverse momentum are scaled with charged hadron pseudorapidity density at midrapidity. In terms of p T and rapidity y γ , Eq.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

The color dipole picture for prompt photon production in pp and pPb collisions at the CERN-LHC

2020

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A study on the prompt photon production within the QCD color dipole picture with emphasis in pp and p A collisions at the LHC energy regimes is performed. We present predictions for the differential cross section as a function of photon transverse momentum at different rapidity bins considering updated phenomenological color dipole models, which take into account the QCD gluon saturation physics. The results are directly compared to the recent experimental measurements provided by CMS and ATLAS Collaborations, showing a reasonable agreement in all rapidity bins with no free parameters. Special attention is given to the IPSAT model given its good description of the data in all rapidity bins from low-to highp T ranges. As a result, a freeparameter approach has succeeded in describing the LHC data for prompt photon production, while new predictions for the 13-TeV data is presented in view of new data to confirm such prospect.

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Section: Numerical Results and Discussionmentioning

confidence: 99%

The color dipole picture for prompt photon production in pp and pPb collisions at the CERN-LHC

2020

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“…It may be due to the interactions of charged particles in medium. The other reason might be that for charged particles we extract λ from integrated yields that include the scaling part up to 2 ÷ 3 GeV/c [41] and the nonscaling tail, while in obtaining Eq. (13) we have assumed that GS is present in the whole experimentally measured range.…”

Section: Charged Particle Multiplicitymentioning

confidence: 99%

“…with δ ∼ 2/3 and λ ∼ 0.2 ÷ 0.35 [41]. Here we have chosen x 0 = 10 −3 for a typical value of Bjorken x where the saturation effects become important.…”

Section: Introductionmentioning

confidence: 99%

Scaling properties of direct photon yields in heavy ion collisions

Khachatryan

Praszałowicz

2020

Eur. Phys. J. C

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A recent analysis from the PHENIX collaboration of available direct photon measurement results in collisions of various systems such as Au+Au, Cu+Cu, and Pb+Pb, at different beam energies ranging from 39 to 2760 GeV, has shown a universal, within experimental uncertainties, multiplicity scaling, in which direct photon $$p_{T}$$ p T -spectra for transverse momenta up to 2 GeV/c are scaled with charged hadron pseudorapidity density at midrapidity raised to power $$\alpha =1.25$$ α = 1.25 . On the other hand, those direct photon $$p_{T}$$ p T -spectra also exhibit geometrical scaling in the similar $$p_{T}$$ p T range. Assuming power-law dependence of the scaled photon spectra for both scaling laws, we formulate two independent conditions for the power $$\alpha $$ α , which overshoot experimental data by $$\sim 10\%$$ ∼ 10 % on average. We discuss possible sources that might improve this estimate.

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“…Similar proposals of scaling can be found in Refs. [30][31][32], where the scaling observed in prompt photon production is related to an universal multiplicity scaling. The latter is studied by using the charged hadron pseudorapidity density at midrapidity, dN h /dη.…”

Section: Theoretical Formalismmentioning

confidence: 99%