Diffractive photoproduction of dijets in ep collisions at HERA

European Physical Journal C 55:2 (2008) 177-191

Authors:

S Chekanov, M Derrick, S Magill, B Musgrave, D Nicholass, J Repond, R Yoshida, MCK Mattingly, M Jechow, N Pavel, AGY Molina, S Antonelli, P Antonioli, G Bari, M Basile, L Bellagamba, M Bindi, D Boscherini, A Bruni, G Bruni, L Cifarelli, F Cindolo, A Contin, M Corradi, S De Pasquale, G Iacobucci, A Margotti, R Nania, A Polini, G Sartorelli, A Zichichi, D Bartsch, I Brock, H Hartmann, E Hilger, HP Jakob, M Jüngst, OM Kind, AE Nuncio-Quiroz, E Paul, R Renner, U Samson, V Schönberg, R Shehzadi, M Wlasenko, NH Brook, GP Heath, JD Morris, M Capua, S Fazio, A Mastroberardino, M Schioppa, G Susinno, E Tassi, JY Kim, ZA Ibrahim, B Kamaluddin, WAT Wan Abdullah, Y Ning, Z Ren, F Sciulli, J Chwastowski, A Eskreys, J Figiel, A Galas, M Gil, K Olkiewicz, P Stopa, L Zawiejski, L Adamczyk, T Bołd, I Grabowska-Bołd, D Kisielewska, J Łukasik, M Przybycień, L Suszycki, A Kotański, W Słomiński, V Adler, U Behrens, C Blohm, A Bonato, K Borras, R Ciesielski, N Coppola, V Drugakov, S Fang, J Fourletova, A Geiser, D Gladkov, P Göttlicher, J Grebenyuk, I Gregor, T Haas, W Hain, A Hüttmann, B Kahle, II Katkov, U Klein, U Kötz

Abstract:

Diffractive photoproduction of dijets was measured with the ZEUS detector at the ep collider HERA using an integrated luminosity of 77.2 pb-1. The measurements were made in the kinematic range Q2 < 1 GeV 2, 0.20IP<0.025, where Q2 is the photon virtuality, y is the inelasticity and xIP is the fraction of the proton momentum taken by the diffractive exchange. The two jets with the highest transverse energy, ET jet, were required to satisfy ET jet>7.5 and 6.5 GeV, respectively, and to lie in the pseudorapidity range -1.5<ηjet<1.5. Differential cross sections were compared to perturbative QCD calculations using available parameterisations of diffractive parton distributions of the proton. © 2008 Springer-Verlag / Società Italiana di Fisica.

Three- and four-jet final states in photoproduction at HERA

Nuclear Physics B 792:1-2 (2008) 1-47

Authors:

S Chekanov, M Derrick, S Magill, B Musgrave, D Nicholass, J Repond, R Yoshida, MCK Mattingly, M Jechow, N Pavel, AG Yagües Molina, S Antonelli, P Antonioli, G Bari, M Basile, L Bellagamba, M Bindi, D Boscherini, A Bruni, G Bruni, L Cifarelli, F Cindolo, A Contin, M Corradi, S De Pasquale, G Iacobucci, A Margotti, R Nania, A Polini, G Sartorelli, A Zichichi, D Bartsch, I Brock, H Hartmann, E Hilger, HP Jakob, M Jüngst, OM Kind, AE Nuncio-Quiroz, E Paul, R Renner, U Samson, V Schönberg, R Shehzadi, M Wlasenko, NH Brook, GP Heath, JD Morris, M Capua, S Fazio, A Mastroberardino, M Schioppa, G Susinno, E Tassi, JY Kim, KJ Ma, ZA Ibrahim, B Kamaluddin, WAT Wan Abdullah, Y Ning, Z Ren, F Sciulli, J Chwastowski, A Eskreys, J Figiel, A Galas, M Gil, K Olkiewicz, P Stopa, L Zawiejski, L Adamczyk, T Bołd, I Grabowska-Bołd, D Kisielewska, J Łukasik, M Przybycień, L Suszycki, A Kotański, W Słomiński, V Adler, U Behrens, I Bloch, C Blohm, A Bonato, K Borras, R Ciesielski, N Coppola, A Dossanov, V Drugakov, J Fourletova, A Geiser, D Gladkov, P Göttlicher, J Grebenyuk, I Gregor, T Haas, W Hain, C Horn, A Hüttmann, B Kahle

Abstract:

Three- and four-jet final states have been measured in photoproduction at HERA using the ZEUS detector with an integrated luminosity of 121   pb -1. The results are presented for jets with transverse energy E Tjet > 6   GeV and pseudorapidity | η jet | < 2.4, in the kinematic region given by the virtuality of the photon Q 2 < 1   GeV 2 and the inelasticity 0.2 ≤ y ≤ 0.85 and in two mass regions defined as 25 ≤ M n j < 50   GeV and M n j ≥ 50   GeV, where M n j is the invariant mass of the n-jet system. The four-jet photoproduction cross section has been measured for the first time and represents the highest-order process studied at HERA. Both the three- and four-jet cross sections have been compared with leading-logarithmic parton-shower Monte Carlo models, with and without multi-parton interactions. The three-jet cross sections have been compared to an O (α α s2) perturbative QCD calculation. © 2007 Elsevier B.V. All rights reserved.

ATF extraction line laser-wire system

Particle Accelerator Conference 2007: Particle Accelerator Conference, 2007. PAC. IEEE (2008)

Authors:

L Deacon, ST Boogert, GA Blair, G Boorman, A Bosco, P Karataev, Laura Corner, N Delerue, B Foster, F Gannaway, D Howell, M Newman, Armin Reichold, R Senanayake, R Walczak, A Aryshev, H Hayano, K Kubo, N Terunuma, U Urakawa

Abstract:

The ATF extraction line laser-wire (LW) aims to achieve a micron-scale laser spot size and to verify that micron scale beam profile measurements can be performed at the International Linear Collider beam delivery system. Recent upgrades to the LW system are presented together with recent results including the first use of the LW as a beam diagnostic tool.

First a tragedy, then farce

Physics World 21:9 (2008) 14-15

Measurement of isolated photon production in deep-inelastic scattering at HERA

European Physical Journal C 54:3 (2008) 371-387

Authors:

FD Aaron, A Aktas, C Alexa, V Andreev, B Antunovic, S Aplin, A Asmone, A Astvatsatourov, S Backovic, A Baghdasaryan, P Baranov, E Barrelet, W Bartel, S Baudrand, M Beckingham, K Begzsuren, O Behnke, O Behrendt, A Belousov, N Berger, JC Bizot, MO Boenig, V Boudry, I Bozovic-Jelisavcic, J Bracinik, G Brandt, M Brinkmann, V Brisson, D Bruncko, FW Büsser, A Bunyatyan, G Buschhorn, L Bystritskaya, AJ Campbell, KB Cantun Avila, F Cassol-Brunner, K Cerny, V Cerny, V Chekelian, A Cholewa, JG Contreras, JA Coughlan, G Cozzika, J Cvach, JB Dainton, K Daum, M Deak, Y De Boer, B Delcourt, M Del Degan, J Delvax, A De Roeck, EA De Wolf, C Diaconu, V Dodonov, A Dubak, G Eckerlin, V Efremenko, S Egli, R Eichler, F Eisele, A Eliseev, E Elsen, S Essenov, A Falkiewicz, PJW Faulkner, L Favart, A Fedotov, R Felst, J Feltesse, J Ferencei, L Finke, M Fleischer, A Fomenko, G Franke, T Frisson, E Gabathuler, J Gayler, S Ghazaryan, S Ginzburgskaya, A Glazov, I Glushkov, L Goerlich, M Goettlich, N Gogitidze, S Gorbounov, M Gouzevitch, C Grab, T Greenshaw, BR Grell, G Grindhammer, S Habib, D Haidt, M Hansson, G Heinzelmann, C Helebrant, RCW Henderson, H Henschel, G Herrera, M Hildebrandt

Abstract:

The production of isolated photons in deep-inelastic scattering ep→eγX is measured with the H1 detector at HERA. The measurement is performed in the kinematic range of negative four-momentum transfer squared 450 GeV. The analysis is based on a total integrated luminosity of 227 pb-1. The production cross section of isolated photons with a transverse energy in the range 3