Measurement of the proton structure function F-2 at very low Q(2) at HERA

Breitweg, J Chekanov, S Derrick, M Krakauer, D Magill, S Musgrave, B Pellegrino, A Repond, J Stanek, R Yoshida, R Mattingly, MCK Abbiendi, G Anselmo, F Antonioli, P Bari, G Basile, M Bellagamba, L Boscherini, D Bruni, A Bruni, G Romeo, GC Castellini, G Cifarelli, L Cindolo, F Contin, A Coppola, N Corradi, M De Pasquale, S Giusti, P Iacobucci, G Laurenti, G Levi, G Margotti, A Massam, T Nania, R Palmonari, F Pesci, A Polini, A Sartorelli, G Garcia, YZ Zichichi, A Amelung, C Bornheim, A Brock, I Coboken, K Crittenden, J Deffner, R Hartmann, H Heinloth, K Hilger, E Irrgang, P Jakob, HP Kappes, A Katz, UF Kerger, R Paul, E Schnurbusch, H Stifutkin, A Tandler, J Voss, KC Weber, A Wieber, H Bailey, DS Barret, O Brook, NH Foster, B Heath, GP Heath, HF McFall, JD Piccioni, D Rodrigues, E Scott, J Tapper, RJ Capua, M Mastroberardino, A Schioppa, M Susinno, G Jeoung, HY Kim, JY Lee, JH Lim, IT Ma, KJ Pac, MY Caldwell, A Liu, W Liu, X Mellado, B Paganis, S Sampson, S Schmidke, WB Sciulli, F Chwastowski, J Eskreys, A Figiel, J Klimek, K Olkiewicz, K Piotrzkowski, K Przybycien, MB Stopa, P Zawiejski, L Bednarek, B Jelen, K Kisielewska, D Kowal, AM Kowalski, T Przybycien, M Rulikowska-Zarebska, E Suszycki, L Szuba, D Kotanski, A Bauerdick, LAT Behrens, U Bienlein, JK Burgard, C Dannheim, D Desler, K Drews, G Fox-Murphy, A Fricke, U Goebel, F Gottlicher, P Graciani, R Haas, T Hain, W Hartner, GF Hasell, D Hebbel, K Johnson, KF Kasemann, M Koch, W Kotz, U Kowalski, H Lindemann, L Lohr, B Martinez, M Milite, M Monteiro, T Moritz, M Notz, D Pelucchi, F Petrucci, MC Rohde, M Saull, PRB Savin, AA Schneekloth, U Selonke, F Sievers, M Stonjek, S Tassi, E Wolf, G Wollmer, U Youngman, C Zeuner, W Coldewey, C Viani, ALD Meyer, A Schlenstedt, S Straub, PB Barbagli, G Gallo, E Pelfer, P Maccarrone, G Votano, L Bamberger, A Benen, A Eisenhardt, S Markun, P Raach, H Wolfle, S Bussey, PJ Bell, M Doyle, AT Lee, SW Lupi, A Macdonald, N McCance, GJ Saxon, DH Sinclair, LE Skillicorn, IO Waugh, R Bohnet, I Gendner, N Holm, U Meyer-Larsen, A Salehi, H Wick, K Garfagnini, A Gialas, I Gladilin, LK Kcira, D Klanner, R Lohrmann, E Poelz, G Zetsche, F Goncalo, R Long, KR Miller, DB Tapper, AD Walker, R Mallik, U Cloth, P Filges, D Ishii, T Kuze, M Nagano, K Tokushuku, K Yamada, S Yamazaki, Y Ahn, SH Lee, SB Park, SK Lim, H Park, IH Son, D Barreiro, F Garcia, G Glasman, C Gonzalez, O Labarga, L del Peso, J Redondo, I Terron, J Barbi, M Corriveau, F Hanna, DS Ochs, A Padhi, S Riveline, M Stairs, DG Wing, M Tsurugai, T Antonov, A Bashkirov, V Danilov, M Dolgoshein, BA Gladkov, D Sosnovtsev, V Suchkov, S Dementiev, RK Ermolov, PF Golubkov, YA Katkov, II Khein, LA Korotkova, NA Korzhavina, IA Kuzmin, VA Lukina, OY Proskuryakov, AS Shcheglova, LM Solomin, AN Vlasov, NN Zotkin, SA Bokel, C Botje, M Brummer, N Engelen, J Grijpink, S Koffeman, E Kooijman, P Schagen, S van Sighem, A Tiecke, H Tuning, N Velthuis, JJ Vossebeld, J Wiggers, L de Wolf, E Acosta, D Bylsma, B Durkin, LS Gilmore, J Ginsburg, CM Kim, CL Ling, TY Boogert, S Cooper-Sarkar, AM Devenish, RCE Grosse-Knetter, J Matsushita, T Quadt, A Ruske, O Sutton, MR Walczak, R Bertolin, A Brugnera, R Carlin, R Dal Corso, F Dosselli, U Dusini, S Limentani, S Morandin, M Posocco, M Stanco, L Stroili, R Turcato, M Voci, C Adamczyk, L Iannotti, L Oh, BY Okrasinski, JR Toothacker, WS Whitmore, JJ Iga, Y D'Agostini, G Marini, G Nigro, A Cormack, C Hart, JC McCubbin, NA Shah, TP Epperson, D Heusch, C Sadrozinski, HFW Seiden, A Wichmann, R Williams, DC Pavel, N Abramowicz, H Dagan, S Kananov, S Kreisel, A Levy, A Abe, T Fusayasu, T Umemori, K Yamashita, T Hamatsu, R Hirose, T Inuzuka, M Kitamura, S Nishimura, T Arneodo, M Cartiglia, N Cirio, R Costa, M Ferrero, MI Maselli, S Monaco, V Peroni, C Ruspa, M Sacchi, R Solano, A Staiano, A Dardo, M Bailey, DC Fagerstroem, CP Galea, R Koop, T Levman, GM Martin, JF Orr, RS Polenz, S Sabetfakhri, A Simmons, D Butterworth, JM Catterall, CD Hayes, ME Heaphy, EA Jones, TW Lane, JB West, BJ Ciborowski, J Ciesielski, R Grzelak, G Nowak, RJ Pawlak, JM Pawlak, R Smalska, B Tymieniecka, T Wroblewski, AK Zakrzewski, JA Zarnecki, AF Adamus, M Gadaj, T Deppe, O Eisenberg, Y Hochman, D Karshon, U Badgett, WF Chapin, D Cross, R Foudas, C Mattingly, S Reeder, DD Smith, WH Vaiciulis, A Wildschek, T Wodarczyk, M Deshpande, A Dhawan, S Hughes, VW Bhadra, S Catterall, C Cole, JE Frisken, WR Hall-Wilton, R Khakzad, M Menary, S

J. Breitweg et al., Measurement of the proton structure function F-2 at very low Q(2) at HERA, PHYS LETT B, 487(1-2), 2000, pp. 53-73

51

INGLESE

Article

Physics

PHYSICS LETTERS B

0370-2693 → ACNP

487

1-2

2000

53 - 73

ISI

0370-2693(20000810)487:1-2<53:MOTPSF>2.0.ZU;2-8

A measurement of the proton structure function F-2(x, Q(2)) is presented in the kinematic range 0.045 GeV2 < Q(2) < 0.65 GeV2 and 6 . 10(-7) < x < 1 . 10(-3). The results were obtained using a data sample corresponding to an integrated luminosity of 3.9 pb(-1) in e(+)p reactions recorded with the ZE US detector at HERA. Information from a silicon-strip tracking detector, in stalled in front of the small electromagnetic calorimeter used to measure t he energy of the final-state positron at small scattering angles, together with an enhanced simulation of the hadronic final state, has permitted the extension of the kinematic range beyond that of previous measurements. The uncertainties in F-2 are typically less than 4%. At the low Q(2) values of the present measurement, the rise of F-2 at low x is slower than observed i n HERA data at higher Q(2) and can be described by Regge theory with a cons tant logarithmic slope partial derivative lnF(2)/partial derivative ln(1/x) . The dependence of F-2 on Q(2) is stronger than at higher Q(2) values, app roaching, at the lowest Q(2) values of this measurement, a region where F-2 becomes nearly proportional to Q(2). (C) 2000 Elsevier Science B.V. All ri ghts reserved.