Next to leading order bremsstrahlung contribution to prompt-photon production

Aurenche, P.; Chiappetta, P.; Fontannaz, M.; Guillet, J. Ph.; Pilon, E.

doi:10.1016/0550-3213(93)90615-v

Cited by 79 publications

(96 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A rather complete numerical study of these uncertainties is carried out. The main feature is that there is no stability zone in the fixed target energy range unlike what has been observed at higher energies [13]. Arbitrarily choosing the scales we show that we can get a reasonable agreement with all considered data except with the E706 [8] data obtained using nuclear targets and the older R806 data [2] from the ISR.…”

supporting

confidence: 63%

“…Finally, when increasing M 2 F from 24 GeV 2 to 300 GeV 2 the optimal predictions decrease by less than 20%. It should be reminded that at much higher energies, in the Tevatron energy range and above, a stable point could be obtained for the inclusive photon cross section [13].…”

Section: Theoretical Framework and Ambiguitiesmentioning

confidence: 99%

“…Despite many years of intense experimental [1,2,3,4,5,6,7,8,9,10] and theoretical [11,12,13,14] efforts the inclusive production of prompt photons in hadronic collisions does not appear to be fully understood. No consensus has been reached concerning the phenomenology of these processes.…”

mentioning

confidence: 99%

See 2 more Smart Citations

A critical phenomenological study of inclusive photon production in hadronic collisions

et al. 1999

Self Cite

View full text Add to dashboard Cite

We discuss fixed target and ISR inclusive photon production and attempt a comparison between theory and experiments. The dependence of the theoretical predictions on the structure functions, and on the renormalization and factorization scales is investigated. The main result of this study is that the data cannot be simultaneously fitted with a single set of scales and structure functions. On the other hand, there is no need for an additional intrinsic k T to force the agreement between QCD predictions and experiments, with the possible exception of one data set. Since the data cover almost overlapping kinematical ranges this raises the question of consistency among data sets. A comparative discussion of some possible sources of experimental uncertainties is sketched.hep-ph/9811382 LAPTH-704/98 LPTHE-Orsay/98/69

show abstract

supporting

confidence: 63%

Section: Theoretical Framework and Ambiguitiesmentioning

confidence: 99%

See 1 more Smart Citation

A critical phenomenological study of inclusive photon production in hadronic collisions

et al. 1999

Self Cite

View full text Add to dashboard Cite

show abstract

“…q ,at leading order. However, one must also account for non-direct production in fragmentation processes from other partons 192 . There is also some uncertainty from factorization and renormalization scale dependence.…”

Section: Methods Of Extracting the Gluon Distributionmentioning

confidence: 99%

Structure Functions of the Nucleon and Their Interpretation

Cooper-Sarkar

Roeck

Devenish

1998

Int. J. Mod. Phys. A

150

171

View full text Add to dashboard Cite

The current status of measurements of the nucleon structure functions and their understanding is reviewed. The xed target experiments E665, CCFR and NMC and the HERA experiments H1 and ZEUS are discussed in some detail. The extraction of parton momentum distribution functions from global ts is described, with particular attention paid to much improved information on the gluon momentum distribution. The status of s measurements from deep inelastic data is reviewed. Models and non-perturbative approaches for the parton input distributions are outlined. The impact on the phenomenology of QCD of the data at very low v alues of the Bjorken x variable is discussed in detail. Recent advances in the understanding of the transition from deep inelastic scattering to photoproduction are summarized. Some brief comments are made on the recent HERA measurements of the ep NC and CC cross-sections at very high Q 2 .

show abstract

“…One major uncertainty in our predictions is expected to come from the fragmentation contribution since the parton-to-photon fragmentation functions are experimentally unmeasured so far, even though very sensible theoretical predictions for them are available [21,25] (see also [14]). In our case, the uncertainty is even larger since, as discussed earlier, we have to stick to a pure LO calculation for the fragmentation contribution in the polarized case, rather than including it on a NLO basis as would be required by consistency.…”

Section: Introductionmentioning

confidence: 99%

Inclusive prompt photon production in polarized pp collisions at HERA-

Gordon

Vogelsang

1996

Physics Letters B

View full text Add to dashboard Cite

We present a NLO study of inclusive polarized prompt photon production in a conceivable fixed target pp mode of HERA with longitudinally polarized protons at √ s = 39 GeV.We analyze the sensitivity of the corresponding double spin asymmetry to the proton's polarized gluon distribution ∆g and estimate the expected statistical precision in its determination. The main theoretical uncertainties in the predictions are examined.It has recently become possible to perform a complete and consistent study of longitudinally polarized deep-inelastic scattering (DIS) in next-to-leading order (NLO) of QCD, since the spin-dependent two-loop splitting functions, needed for the NLO evolution of the polarized parton distributions, have become available [1,2]. A first such phenomenological NLO analysis, taking into account all available experimental data on polarized DIS [3] has been presented in [4], followed by the analyses [5,6]. The studies of [4,6] have shown that present polarized DIS data are still quite far from providing accurate knowledge about the nucleon's spin-dependent sea quark and gluon distributions. This holds true, in particular, for the polarized gluon density ∆g, the x-shape of which seems to be hardly constrained at all [4,6] by the DIS data, even though a tendency towards a sizeable positive total gluon polarization, 1 0 ∆g(x, Q 2 = 4 GeV 2 )dx 1, was found [4,5,6]. Thus, there is clearly some need for independent information on ∆g. For this purpose, it seems expedient to look at processes for which ∆g enters in leading order (LO) already, rather than as a NLO correction as for the spin-dependent DIS structure function g 1 . One of such processes is inclusive large-p T prompt photon production in collisions of longitudinally polarized protons, p p → γX [7,8,9,10]. In the unpolarized case where this process has been studied in a huge number of experiments it has been an invaluable tool for pinning down the proton's unpolarized gluon distribution g(x, Q 2 ) [11,12,13,14]. Hence prompt photon production with polarized beams seems a promising source for obtaining information on ∆g.It is being discussed as one future option for HERA to polarize its 820 GeV proton beam. If this can be achieved, one could use the beam in a fixed target experiment, scattering it off an internal polarized nucleon target. This conceivable constellation, dubbed , would yield √ s ≈ 39 GeV and thus could provide information complementary to that obtained from planned similar spin physics experiments at much higher energies at the RHIC collider [16]. Theoretical predictions for polarized prompt photon production at √ s ≈ 40 GeV have been made in the past [8,10], taking into account the spin-dependent 'direct' subprocess cross sections for ab → γX (a, b = q,q, g) including their full NLO QCD corrections as calculated in [8,9]. From the experience in the unpolarized case, the inclusion of NLO corrections is expected to be quite important 1 in order to make reliable predictions. The main shortcoming of the studies [8,10] was, however...

show abstract

Next to leading order bremsstrahlung contribution to prompt-photon production

Cited by 79 publications

References 9 publications

A critical phenomenological study of inclusive photon production in hadronic collisions

A critical phenomenological study of inclusive photon production in hadronic collisions

Structure Functions of the Nucleon and Their Interpretation

Inclusive prompt photon production in polarized pp collisions at HERA-

Contact Info

Product

Resources

About