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

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
G. Sampaio dos Santos ◽  
G. Gil da Silveira ◽  
M. V. T. Machado
Keyword(s):  
Cross Section ◽  
Free Parameter ◽  
Good Description ◽  
Photon Production ◽  
Prompt Photon ◽  
Color Dipole ◽  
Gluon Saturation ◽  
Free Parameters ◽  
Parameter Approach ◽  
Dipole Picture

AbstractA study on the prompt photon production within the QCD color dipole picture with emphasis in pp and pA 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 high-$$p_{T}$$ p T ranges. As a result, a free-parameter 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.

scholarly journals Investigating the Prompt Photon Production at the LHC Energies

2017 ◽  
Vol 45 ◽  
pp. 1760061
Author(s):  
Glauber S. dos Santos ◽  
Magno V. T. Machado
Keyword(s):  
Transverse Momentum ◽  
Cross Section ◽  
Photon Production ◽  
Prompt Photon ◽  
Dipole Cross Section ◽  
High Energies ◽  
Color Dipole ◽  
Momentum Distributions

We investigate the rapidity and transverse momentum distributions of the prompt photon production at the LHC energies considering the color dipole approach. We compare the predictions from distinct models for the dipole cross section, where parton saturation models at high energies are expected to be important at the forward rapidities in [Formula: see text] and [Formula: see text] collisions at the LHC.

scholarly journals The Color Dipole Picture and the Ratio of the Longitudinal to the Transverse Photoabsorption Cross Section

2009 ◽  
Author(s):  
Dieter Schildknecht ◽  
Roberto Fiore ◽  
Igor Ivanov ◽  
Alessandro Papa ◽  
Jacques Soffer
Keyword(s):  
Cross Section ◽  
Photoabsorption Cross Section ◽  
Color Dipole ◽  
Dipole Picture

scholarly journals SCALING IN γ*p TOTAL CROSS-SECTIONS, SATURATION AND THE GLUON DENSITY

2001 ◽  
Vol 16 (28) ◽  
pp. 1829-1839 ◽  
Author(s):  
DIETER SCHILDKNECHT ◽  
BERND SURROW ◽  
MIKHAIL TENTYUKOV
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Gluon Density ◽  
Hera Data ◽  
Leading Order ◽  
Total Cross Sections ◽  
Vector Dominance ◽  
Color Dipole ◽  
Dipole Picture ◽  
Increasing Function

Including the new HERA data, the γ*p total cross-section is analyzed in the generalized vector dominance/color-dipole picture (GVD/CDP) that contains scaling in [Formula: see text], where Λ2(W2) is an increasing function of W2. At any Q2, for W2→∞, the cross-sections for virtual and real photons become identical, σγ*p (W2,Q2)/σγp (W2)→ 1. The gluon density deduced from the color-dipole cross-section fulfills the leading order DGLAP relationship. Evolution à la DGLAP breaks down for η≲0.1.

scholarly journals Measurement of the Isolated Prompt Photon Production Cross Section inppCollisions ats=7  TeV

2011 ◽  
Vol 106 (8) ◽  
Author(s):  
V. Khachatryan ◽  
A. M. Sirunyan ◽  
A. Tumasyan ◽  
W. Adam ◽  
T. Bergauer ◽  
...  
Keyword(s):  
Cross Section ◽  
Production Cross Section ◽  
Production Cross ◽  
Photon Production ◽  
Prompt Photon

scholarly journals THE RARITA–SCHWINGER FIELD: RENORMALIZATION AND PHENOMENOLOGY

2007 ◽  
Vol 22 (24) ◽  
pp. 4495-4518 ◽  
Author(s):  
A. E. KALOSHIN ◽  
V. P. LOMOV
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Free Parameter ◽  
Reasonable Agreement ◽  
Good Description ◽  
Partial Wave Analysis ◽  
Wave Analysis ◽  
Case Application ◽  
Energy Plane ◽  
Field Renormalization

We discuss renormalization of propagator of interacting Rarita–Schwinger field. Spin-3/2 contribution after renormalization takes usual resonance form. For nonleading spin-1/2 terms we found procedure, which guarantees absence of poles in energy plane. The obtained renormalized propagator has one free parameter and is a straight generalization of the famous free propagator of Moldauer and Case. Application of this propagator for production of Δ++(1232) in π+ p →π+p leads to good description of total cross-section and to reasonable agreement with results of partial wave analysis.

A study on the isolated photon production in nuclear collisions at the CERN-LHC energies

2022 ◽  
Author(s):  
Glauber Sampaio dos Santos ◽  
Gustavo Gil Da Silveira ◽  
Magno Valério Trindade Machado
Keyword(s):  
Transverse Momentum ◽  
Heavy Ion ◽  
High Energy ◽  
Photon Production ◽  
Prompt Photon ◽  
Invariant Cross Section ◽  
Geometrical Properties ◽  
Nuclear Collisions ◽  
First Case ◽  
Color Dipole

Abstract An analysis of prompt photon production in high energy nuclear collisions at the LHC is performed within the parton saturation picture taking into account the updated phenomenological color dipole models. Comparison between $\langle N_{coll}\rangle$ scaling for hard scattering in heavy-ion collisions and the $N_{part}$-scaling based on geometric scaling arguments has been done. The predictions are parameter free in the first case whereas a dependence on the constant of proportionality $\kappa$ between the number of participants and the nuclear saturation scale appears in the second case. This parameter has been analyzed in the prompt photon spectrum at small transverse momentum even though no fitting procedure was performed. Results are confronted with the measurements made by the ALICE, ATLAS, and CMS experiments in terms of photon transverse momentum at different rapidity bins. We show that the prompt photon production exhibits distinct scalings in $AA$ events associated to geometrical properties of the collision and can be properly addressed in the color dipole formalism. Based on the $N_{part}$-scaling, an analytical parametrization for the invariant cross section is provided and employed to predict the $x_T$-scaling in measurements. For $\kappa$ of order of unit the theoretical scaling curve correctly describes data in the range $x_T\leq 5\times 10^{-2}$.

scholarly journals PROMPT PHOTON PRODUCTION IN p-p COLLISIONS

1995 ◽  
Vol 10 (20n21) ◽  
pp. 2941-2960 ◽  
Author(s):  
J. CLEYMANS ◽  
E. QUACK ◽  
K. REDLICH ◽  
D.K. SRIVASTAVA
Keyword(s):  
Experimental Data ◽  
Cross Section ◽  
Cross Sections ◽  
Systematic Study ◽  
Structure Functions ◽  
Photon Production ◽  
Prompt Photon ◽  
Centre Of Mass ◽  
The Cross ◽  
Photon Cross Section

A systematic study of the inclusive photon cross-section in p-p collisions is presented. The dependence of the γ rates on the renormalization and factorization scales is discussed. A comparison is made with experimental data for centre-of-mass energies ranging from 23 GeV to 1.8 TeV. Predictions of the cross-sections are given for two different sets of structure functions for RHIC and LHC energies.

scholarly journals Measurement of the differential cross section for isolated prompt photon production inppcollisions at 7 TeV

2011 ◽  
Vol 84 (5) ◽  
Author(s):  
S. Chatrchyan ◽  
V. Khachatryan ◽  
A. M. Sirunyan ◽  
A. Tumasyan ◽  
W. Adam ◽  
...  
Keyword(s):  
Differential Cross Section ◽  
Cross Section ◽  
Differential Cross ◽  
Photon Production ◽  
Prompt Photon

scholarly journals Photons as Probes of Gluon Saturation in DiluteDense Collisions

Proceedings ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 33
Author(s):  
Sanjin Benić ◽  
Kenji Fukushima ◽  
Oscar Garcia-Montero ◽  
Raju Venugopalan
Keyword(s):  
Cross Section ◽  
Center Of Mass ◽  
Effective Field ◽  
Photon Production ◽  
Color Glass ◽  
Leading Order ◽  
Small X ◽  
Gluon Saturation ◽  
Gluon Distributions ◽  
Good Agreement

We use the Color Glass Condensate (CGC) effective field theory (EFT) to calculate inclusive photon production to leading order q g → q γ , (LO), and next-to leading order g g → q q ¯ γ (NLO) at LHC energies. These processes dominate the photon production at small-x , where x ≲ 0 . 01 in the target and projectile protons. We show that the NLO contribution dominates at values of x typical at the LHC, since its cross-section is sensitive to the gluon distributions in both protons. We perform a comparison of our results to the available inclusive photon data, from ATLAS and CMS at center-of-mass energies of 2 . 76 and 7 TeV . This data lies in the range k ⊥ > 20 GeV . We show that for this range, the k ⊥ -factorized cross-section converges to the full CGC EFT result, and can be used for the comparison. We find that it gives good agreement with experimental results. Our results are to be considered as a first step towards constraining unintegrated gluon distributions, which will be continued for larger systems, where coherent scatterings are enhanced.

Understanding the cross section for isolated prompt photon production

1990 ◽  
Vol 248 (3-4) ◽  
pp. 371-377 ◽  
Author(s):  
Edmond L. Berger ◽  
Jianwei Qiu
Keyword(s):  
Cross Section ◽  
Photon Production ◽  
Prompt Photon ◽  
The Cross
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