Measurement of single spin asymmetry for direct photon production in pp collisions at 200 GeV/c

Adams, T.; Achurin, N.; Belikov, N.I.; Bravar, A.; Bystrický, J.; Corcoran, M.; Cossairt, J.D.; Cranshaw, J.; Derevschikov, A. A.; En’yo, H.; Funahashi, H.; Goto, Y.; Grachov, O.; Grosnick, D.; Hill, D.; Iijima, T.; Imai, K.; Itow, Y.; Iwatani, Kazuo; Krueger, K.; Kuroda, K.; Lehar, F.; Lesquen, A. de; Lopiano, D.; Luehring, F.; Mäki, T.; Makino, S.; Masaike, A.; Matulenko, Yu. A.; Meschanin, A.; Michalowicz, A.; Miller, Donald H.; Miyake, Kazumasa; Nagamine, T.; Nessi‐Tedaldi, F.; Nessi, M.; Nguyen, C.; Nurushev, S. B.; Ōhashi, Y.; Onel, Y.; Patalakha, D. I.; Pauletta, G.; Penzo, A.; Read, A. L.; Roberts, J.; Rossum, L. van; Rykov, V. L.; Saito, N.; Salvato, G.; Schiavon, P.; Shima, T.; Skeens, J.; Solov'yanov, V.L.; Spinka, H. M.; Takashima, R.; Takéutchi, F.; Tamura, N.; Tanaka, N.; Underwood, D. G.; Vasiliev, A.; Villari, A.; White, J. L.; Yamashita, Shinji; Yokosawa, A.; Yoshida, T.; Zanetti, A.

doi:10.1016/0370-2693(94)01695-9

Cited by 50 publications

(39 citation statements)

References 27 publications

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“…The later, shown separately by the dot-dashed line also explains the scaled pp data from E704 experiment [33]. We observe that the photon spectra for the initial velocity profile given by Eq.…”

Section: Resultssupporting

confidence: 64%

“…Experimental data on hard photons does not exist at this energy. Therefore, the "data" at √ s = 17.3 GeV is obtained from the data at √ s = 19.4 GeV of the E704 collaboration [33] by using the scaling relation: [9]. However, such a scaling may be spoiled in perturbative QCD due to the momentum dependence of the strong coupling, α s and from the scaling violation of structure functions, resulting in faster decrease of the cross section than 1/s 2 .…”

Section: Hard Qcd Photonsmentioning

confidence: 99%

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Photons from quark gluon plasma and hot hadronic matter

Alam

2003

Pramana - J Phys

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Abstract. The productions of real photons from quark gluon plasma and hot hadronic matter formed after the nucleus -nucleus collisions at ultra-relativistic energies are discussed. The effects of the spectral shift of the hadrons at finite temperature on the production of photons are investigated. On the basis of the present analysis it is shown that the photon spectra measured by WA98 collaboration in Pb + Pb collisions at CERN SPS energies can be explained by both QGP as well as hadronic initial states if the spectral shift of hadrons at finite temperature is taken into account. Several other works on the analysis of WA98 photon data have also been briefly discussed.

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Section: Resultssupporting

confidence: 64%

Section: Hard Qcd Photonsmentioning

confidence: 99%

Photons from quark gluon plasma and hot hadronic matter

Alam

2003

Pramana - J Phys

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“…1 we compare our results for p + p at √ s = 19.4 GeV, for various intrinsic k 2 t , to E704 data [4]. Clearly, the calculation assuming pure DGLAP evolution, i.e.…”

Section: Prhep Hep2001mentioning

confidence: 80%

Nuclear broadening effects on hard prompt photons at CERN-SPS and BNL-RHIC energies

Gerland¹,

Stöcker²,

Dumitru³

et al. 2001

Proceedings of International Europhysics Conference on High Energy Physics — PoS(hep2001)

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We discuss nuclear broadening of the intrinsic transverse momentum of partons in the initial state, and its influence on the p t distribution of prompt photons.Comparing to WA98 data from Pb+Pb collisions at √ s = 17.4A GeV we find evidence for the presence of nuclear broadening at high p t in this hard process. Below p t ∼ 2.7 GeV the photon distribution is due to small momentum transfer processes. At RHIC energy, √ s = 200A GeV, the effect of intrinsic transverse momentum on the spectrum of prompt photons is less prominent. Below p t = 2 − 3 GeV the contribution from large momentum transfers flattens out, and we expect that region to be dominated by soft contributions.

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“…Instead, prompt photon yields for proton-induced reactions on fixed targets at 200 GeV are shown in Fig. 3 for comparison 16,17,18 . These results have been scaled for comparison with the present measurements according to the calculated average number of nucleon- nucleon collisions (660) for the central Pb+Pb event selection and according to the beam energy under the assumption that Ed 3 σ γ /dp 3 = f (x T )/s 2 , where…”

Section: Resultsmentioning

confidence: 99%

Direct photon production in 158 A GeV 208Pb+208Pb collisions

Peitzmann

2001

Nuclear Physics A

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FOR THE WA98 COLLABORATIONA measurement of direct photon production in 208 Pb+ 208 Pb collisions at 158 A GeV has been carried out in the CERN WA98 experiment. The invariant yield of direct photons in central collisions is extracted as a function of transverse momentum in the interval 0.5 < p T < 4 GeV/c. A significant direct photon signal, compared to statistical and systematical errors, is seen at p T > 1.5 GeV/c. The results constitute the first observation of direct photons in ultrarelativistic heavy-ion collisions which could be significant for diagnosis of quark gluon plasma formation.

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Measurement of single spin asymmetry for direct photon production in pp collisions at 200 GeV/c

Cited by 50 publications

References 27 publications

Photons from quark gluon plasma and hot hadronic matter

Photons from quark gluon plasma and hot hadronic matter

Nuclear broadening effects on hard prompt photons at CERN-SPS and BNL-RHIC energies

Direct photon production in 158 A GeV 208Pb+208Pb collisions

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