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

ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS 69:4 (1996) 607-620

Authors:

M Derrick, D Krakauer, S Magill, D Mikunas, B Musgrave, J Repond, R Stanek, RL Talaga, H Zhang, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, P Bruni, GC Romeo, G Castellini, M Chiarini, L Cifarelli, F Cindolo, A Contin, M Corradi, I Gialas, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, C Nemoz, F Palmonari, A Polini, G Sartorelli, R Timellini, YZ Garcia, A Zichichi, A Bornheim, J Crittenden, K Desch, B Diekmann, T Doeker, M Eckert, L Feld, A Frey, M Geerts, M Grothe, H Hartmann, K Heinloth, L Heinz, E Hilger, HP Jakob, UF Katz, S Mengel, J Mollen, E Paul, M Pfeiffer, C Rembser, D Schramm, J Stamm, R Wedemeyer, S CampbellRobson, A Cassidy, WN Cottingham, N Dyce, B Foster, S George, ME Hayes, GP Heath, HF Heath, CJS Morgado, JA OMara, D Piccioni, DG Roff, RJ Tapper, R Yoshida, RR Rau, M Arneodo, R Ayad, M Capua, A Garfagnini, L Iannotti, M Schioppa, G Susinno, A Bernstein, A Caldwell, N Cartiglia, JA Parsons, S Ritz, F Sciulli, PB Straub, L Wai, S Yang, Q Zhu, P Borzemski, J Chwastowski, A Eskreys, K Piotrzkowski, M Zachara, L Zawiejski, L Adamczyk, B Bednarek, K Jelen, D Kisielewska, T Kowalski, M Przybycien, E RulikowskaZarebska, L Suszycki, J Zajac, A Kotanski, LAT Bauerdick, U Behrens, H Beier, JK Bienlein, C Coldewey, O Deppe, K Desler, G Drews, M Flasinski, DJ Gilkinson, C Glasman, P Gottlicher, J GrosseKnetter, B Gutjahr, T Haas, W Hain, D Hasell, H Hessling, Y Iga, KF Johnson, P Joos, M Kasemann, R Klanner, W Koch, L Kopke, U Kotz, H Kowalski, J Labs, A Ladage, B Lohr, M Lowe, D Luke, J Mainusch, O Marczak, T Monteiro, JST Ng, S Nickel, D Notz, K Ohrenberg, M Roco, M Rohde, J Roldan, U Schneekloth, W Schulz, F Selonke, E Stiliaris, B Surrow, T Voss, D Westphal, G Wolf, C Youngman, W Zeuner, JF Zhou, HJ Grabosch, A Kharchilava, A Leich, SM Mari, MCK Mattingly, A Meyer, S Schlenstedt, N Wulff, G Barbagli, E Gallo, P Pelfer, G Anzivino, G Maccarrone, S DePasquale, L Votano, A Bamberger, S Eisenhardt, A Freidhof, S SoldnerRembold, J Schroeder, T Trefzger, NH Brook, PJ Bussey, AT Doyle, DH Saxon, ML Utley, AS Wilson, A Dannemann, U Holm, D Horstmann, T Neumann, R Sinkus, K Wick, E Badura, BD Burow, L Hagge, E Lohrmann, J Milewski, M Nakahata, N Pavel, G Poelz, W Schott, F Zetsche, TC Bacon, N Bruemmer, I Butterworth, VL Harris, BYH Hung, KR Long, DB Miller, PPO Morawitz, A Prinias, JK Sedgbeer, AF Whitfield, U Mallik, E McCliment, MZ Wang, SM Wang, JT Wu, P Cloth, D Filges, SH An, SM Hong, SW Nam, SK Park, MH Suh, SH Yon, R Imlay, S Kartik, HJ Kim, RR McNeil, W Metcalf, VK Nadendla, F Barreiro, G Cases, JP Fernandez, R Graciani, JM Hernandez, L Hervas, L Labarga, M Martinez, J delPeso, J Puga, J Terron, JF deTroconiz, GR Smith, F Corriveau, DS Hanna, J Hartmann, LW Hung, JN Lim, CG Matthews, PM Patel, LE Sinclair, DG Stairs, M StLaurent, R Ullmann, G Zacek, V Bashkirov, BA Dolgoshein, A Stifutkin, GL Bashindzhagyan, PF Ermolov, LK Gladilin, YA Golubkov, VD Kobrin, IA Korzhavina, VA Kuzmin, OY Lukina, AS Proskuryakov, AA Savin, LM Shcheglova, AN Solomin, NP Zotov, M Botje, F Chlebana, A Dake, J Engelen, M deKamps, P Kooijman, A Kruse, H Tiecke, W Verkerke, M Vreeswijk, L Wiggers, E deWolf, R vanWoudenberg, D Acosta, B Bylsma, LS Durkin, J Gilmore, K Honscheid, C Li, TY Ling, KW McLean, P Nylander, IH Park, TA Romanowski, R Seidlein, DS Bailey, A Byrne, RJ Cashmore, AM CooperSarkar, RCE Devenish, N Harnew, M Lancaster, L Lindemann, JD McFall, C Nath, VA Noyes, A Quadt, JR Tickner, H Uijterwaal, R Walczak, DS Waters, FF Wilson, T Yip, G Abbiendi, A Bertolin, R Brugnera, R Carlin, F DalCorso, M DeGiorgi, U Dosselli, S Limentani, M Morandin, M Posocco, L Stanco, R Stroili, C Voci, J Bulmahn, JM Butterworth, RG Feild, BY Oh, JR Okrasinski, JJ Whitmore, G DAgostini, G Marini, A Nigro, E Tassi, JC Hart, NA McCubbin, K Prytz, TP Shah, TL Short, E Barberis, T Dubbs, C Heusch, M VanHook, W Lockman, JT Rahn, HFW Sadrozinski, A Seiden, DC Williams, J Biltzinger, RJ Seifert, O Schwarzer, AH Walenta, G Zech, H Abramowicz, G Briskin, S Dagan, C HandelPikielny, A Levy, JI Fleck, T Hasegawa, M Hazumi, T Ishii, M Kuze, S Mine, Y Nagasawa, M Nakao, I Suzuki, K Tokushuku, S Yamada, Y Yamazaki, M Chiba, R Hamatsu, T Hirose, K Homma, S Kitamura, Y Nakamitsu, K Yamauchi, R Cirio, M Costa, MI Ferrero, L Lamberti, S Maselli, C Peroni, R Sacchi, A Solano, A Staiano, M Dardo, DC Bailey, D Bandyopadhyay, F Benard, M Brkic, DM Gingrich, GF Hartner, KK Joo, GM Levman, JF Martin, RS Orr, S Polenz, CR Sampson, RJ Teuscher, CD Catterall, TW Jones, PB Kaziewicz, JB Lane, RL Saunders, J Shulman, K Blankenship, B Lu, LW Mo, W Bogusz, K Charchula, J Ciborowski, J Gajewski, G Grzelak, M Kasprzak, M Krzyzanowski, K Muchorowski, RJ Nowak, JM Pawlak, T Tymieniecka, AK Wroblewski, JA Zakrzewski, AF Zarnecki, M Adamus, Y Eisenberg, U Karshon, D Revel, D ZerZion, L Ali, WF Badgett, B Behrens, S Dasu, C Fordham, C Foudas, A Goussiou, RJ Loveless, DD Reeder, S Silverstein, WH Smith, A Vaiciulis, M Wodarczyk, T Tsurugai, S Bhadra, ML Cardy, CP Fagerstroem, WR Frisken, KM Furutani, M Khakzad, WN Murray, WB Schmidke

Measurement of thee reaction gamma*p->phi p in deep, inelastic e(+)p scattering at HERA

PHYSICS LETTERS B 380:1-2 (1996) 220-234

Authors:

M Derrick, D Krakauer, S Magill, D Mikunas, B Musgrave, JR Okrasinski, J Repond, R Stanek, RL Talaga, H Zhang, MCK Mattingly, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, P Bruni, GC Romeo, G Castellini, L Cifarelli, F Cindolo, A Contin, M Corradi, I Gialas, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, F Palmonari, A Polini, G Sartorelli, YZ Garcia, A Zichichi, C Amelung, A Bornheim, J Crittenden, R Deffner, T Doeker, K Eckert, L Feld, A Frey, M Geerts, M Grothe, H Hartmann, K Heinloth, L Heinz, E Hilger, HP Jakob, UF Katz, S Mengel, E Paul, M Pfeiffer, C Rembser, D Schramm, J Stamm, R Wedemeyer, S CampbellRobson, A Cassidy, WN Cottingham, N Dyce, B Foster, S George, ME Hayes, GP Heath, HF Heath, D Piccioni, DG Roff, RJ Tapper, R Yoshida, M Arneodo, R Ayad, M Capua, A Garfagnini, L Iannotti, M Schioppa, G Susinno, A Caldwell, N Cartiglia, Z Jing, W Liu, JA Parsons, S Ritz, F Sciulli, PB Staub, L Wai, S Yang, Q Zhu, P Borzemski, J Chwastowski, A Eskreys, Z Jakubowski, MB Przybycien, M Zachara, L Zawiejski, L Adamczyk, B Bednarek, K Jelen, D Kisielewska, T Kowalski, M Przybycien, E RulikowskaZarebska, L Suszycki, J Zajac, Z Dulinski, A Kotanski, G Abbiendi, LAT Bauerdick, U Behrens, H Beier, JK Bienlein, G Cases, O Deppe, K Desler, G Drews, M Flasinski, DJ Gilkinson, C Glasman, P Gottlicher, J GrosseKnetter, T Haas, W Hain, D Hasell, H Hessling, Y Iga, KF Johnson, P Joos, M Kasemann, R Klanner, W Koch, U Kotz, H Kowalski, J Labs, A Ladage, B Lohr, M Lowe, D Luke, J Mainusch, O Manczak, J Milewski, T Monteiro, JST Ng, D Notz, K Ohrenberg, K Piotrzkowski, M Roco, M Rohde, J Roldan, U Schneekloth, W Schulz, F Selonke, B Surrow, T Voss, D Westphal, G Wolf, U Wollmer, C Youngman, W Zeuner, HJ Grabosch, A Kharchilava, SM Mari, A Meyer, S Schlenstedt, N Wulff, G Barbagli, E Gallo, P Pelfer, G Maccarrone, S DePasquale, L Votano, A Bamberger, S Eisenhardt, T Trefzger, S Wolfle, JT Bromley, NH Brook, PJ Bussey, AT Doyle, DH Saxon, LE Sinclair, ML Utley, AS Wilson, A Dannemann, U Holm, D Horstmann, R Sinkus, K Wick, BD Burow, L Hagge, E Lohrmann, N Pavel, G Poelz, W Schott, F Zetsche, TC Bacon, N Brummer, I Butterworth, VL Harris, G Howell, BHY Hung, L Lamberti, KR Long, DB Miller, A Prinias, JK Sedgbeer, D Sideris, AF Whitfield, U Mallik, MZ Wang, SM Wang, JT Wu, P Cloth, D Filges, SH An, GH Cho, BJ Ko, SB Lee, SW Nam, HS Park, SK Park, S Kartik, HJ Kim, RR McNeil, W Metcalf, VK Nadendla, F Barreiro, JP Fernandez, R Graciani, JM Hernandez, L Hervas, L Labarga, M Martinez, J delPeso, J Puga, J Terron, JF deTroconiz, F Corriveau, DS Hanna, J Hartmann, LW Hung, JN Lim, CG Matthews, PM Patel, M Riveline, DG Stairs, M StLaurent, R Ullmann, G Zacek, T Tsurugai, V Bashkirov, BA Dolgoshein, A Stifutkin, GL Bashindzhagyan, PF Ermolov, LK Gladilin, YA Golubkov, VD Kobrin, IA Korzhavina, VA Kuzmin, OY Lukina, AS Proskuryakov, AA Savin, LM Shcheglova, AN Solomin, NP Zotov, M Botje, F Chlebana, J Engelen, M deKamps, P Kooijman, A Kruse, A vanSighem, H Tiecke, W Verkerke, J Vossebeld, M Vreeswijk, L Wiggers, E deWolf, R vanWoudenberg, D Acosta, B Bylsma, LS Durkin, J Gilmore, C Li, TY Ling, P Nylander, IH Park, TA Rowanowski, DS Bailey, RJ Cashmore, AM CooperSarkar, RCE Devenish, N Harnew, M Lancaster, L Lindemann, JD McFall, C Nath, VA Noyes, A Quadt, JR Tickner, H Uijterwaal, R Walczak, DS Waters, FF Wilson, T Yip, A Bertolin, R Brugnera, R Carlin, F DalCorso, M DeGiorgi, U Dosselli, S Limentani, M Morandin, M Posocco, L Stanco, R Stroili, C Voci, F Zuin, J Bulmahn, RG Feild, BY Oh, JJ Whitmore, G DAgostini, G Marini, A Nigro, E Tassi, JC Hart, NA McCubbin, TP Shah, E Barberis, T Dubbs, C Heusch, M VanHook, W Lockman, JT Rahn, HFW Sadrozinski, A Seiden, DC Williams, J Biltzinger, RJ Seifert, O Schwarzer, AH Walenta, G Zech, H Abramowicz, G Briskin, S Dagan, A Levy, JI Fleck, M Inuzuka, T Ishii, M Kuze, S Mine, M Nakao, I Suzuki, K Tokushuku, K Umemori, S Yamada, Y Yamazaki, M Chiba, R Hamatsu, T Hirose, K Homma, S Kitamura, T Matsushita, K Yamauchi, R Cirio, M Costa, MI Ferrero, S Maselli, C Peroni, R Sacchi, A Solano, A Staiano, M Dardo, DC Bailey, F Benard, M Brkic, CP Fagerstroem, GF Hartner, KK Joo, GM Levman, JF Martin, RS Orr, S Polenz, CR Sampson, D Simmons, RJ Teuscher, JM Butterworth, CD Catterall, TW Jones, PB Kaziewicz, JB Lane, RL Saunders, J Shulman, MR Sutton, B Lu, LW Mo, W Bogusz, J Ciborowski, J Gajewski, G Grzelak, M Kasprzak, M Krzyzanowski, K Muchorowski, RJ Nowak, JM Pawlak, T Tymieniecka, AK Wroblewski, JA Zakrzewski, AF Zarnecki, M Adamus, C Coldewey, Y Eisenberg, D Hochman, U Karshon, D Revel, D ZerZion, WF Badgett, J Breitweg, D Chapin, R Cross, S Dasu, C Foudas, RJ Loveless, S Mattingly, DD Reeder, S Silverstein, WH Smith, A Vaiciulis, M Wodarczyk, S Bhadra, ML Cardy, WR Frisken, M Khakzad, WN Murray, WB Schmidke

Observation of events with an energetic forward neutron in deep inelastic scattering at HERA

PHYSICS LETTERS B 384:1-4 (1996) 388-400

Authors:

M Derrick, D Krakauer, S Magill, D Mikunas, B Musgrave, JR Okrasinski, J Repond, R Stanek, RL Talaga, H Zhang, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, P Bruni, GC Romeo, G Castellini, L Cifarelli, E Cindolo, A Contin, M Corradi, I Gialas, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, E Palmonari, A Polini, G Sartorelli, YZ Garcia, A Zichichi, C Amelung, A Bornheim, J Crittenden, R Deffner, T Doeker, M Eckert, L Feld, A Frey, M Geerts, M Grothe, H Hartmann, K Heinloth, L Heinz, E Hilger, HP Jakob, UF Katz, S Mengel, E Paul, M Pfeiffer, C Rembser, D Schramm, J Stamm, R Wedemeyer, S CampbellRobson, A Cassidy, WN Cottingham, N Dyce, B Foster, S George, ME Hayes, GP Heath, HF Heath, D Piccioni, DG Roff, RJ Tapper, R Yoshida, M Ameodo, R Ayad, M Capua, A Garfagnini, L Iannotti, M Schioppa, G Susinno, A Caldwell, N Cartiglia, Z Jing, W Liu, JA Parsons, S Ritz, F Sciulli, PB Straub, L Wai, S Yang, Q Zhu, P Borzemski, J Chwastowski, A Eskreys, Z Jakubowski, MB Przybycien, M Zachara, L Zawiejski, L Adamczyk, B Bednarek, K Jelen, D Kisielewska, T Kowalski, M Przybycien, E RulikowskaZarebska, L Suszycki, J Zajac, Z Dulinski, A Kotanski, G Abbiendi, LAT Bauerdick, U Behrens, H Beier, JK Bienlein, G Cases, O Deppe, K Desler, G Drews, M Flasinski, DJ Gilkinson, C Glasman, P Gottlicher, J GrosseKnetter, T Haas, W Hain, D Hasell, H Hessling, Y Iga, KF Johnson, P Joos, M Kasemann, R Klanner, W Koch, U Kotz, H Kowalski, J Labs, A Ladage, B Lohr, M Lowe, D Luke, J Mainusch, O Manczak, J Milewski, T Monteiro, JST Ng, D Notz, K Ohrenberg, K Piotrzkowski, M Roco, M Rohde, J Roldan, U Schneekloth, W Schulz, F Selonke, B Surrow, T Voss, D Westphal, G Wolf, U Wollmer, C Youngman, W Zeuner, HJ Grabosch, A Kharchilava, SM Mari, A Meyer, S Schlenstedt, N Wulff, G Barbagli, E Gallo, P Pelfer, G Maccarrone, S DePasquale, L Votano, A Bamberger, S Eisenhardt, T Trefzger, S Wolfle, JT Bromley, HN Brook, PJ Bussey, AT Doyle, DH Saxon, LE Sinclair, ML Utley, AS Wilson, A Dannemann, U Holm, D Horstmann, R Sinkus, K Wick, BD Burow, L Hagge, E Lohrmann, G Poelz, W Schott, F Zetsche, TC Bacon, N Brummer, I Butterworth, VL Harris, G Howell, BHY Hung, L Lamberti, KR Long, DB Miller, N Pavel, A Prinias, JK Sedgbeer, D Sideris, AF Whitfield, U Mallik, MZ Wang, SM Wang, JT Wu, P Cloth, D Filges, SH An, GH Cho, BJ Ko, SB Lee, SW Nam, HS Park, SK Park, S Kartik, HJ Kim, RR McNeil, W Metcalf, VK Nadendla, F Barreiro, JP Fernandez, R Graciani, JM Hernandez, L Hervas, L Labarga, M Martinez, J delPeso, J Puga, J Terron, JF deTroconiz, F Corriveau, DS Hanna, J Hartmann, LW Hung, JN Lim, CG Matthews, PM Patel, M Riveline, DG Stairs, M StLaurent, R Ullmann, G Zacek, V Bashkirov, BA Dolgoshein, A Stifutkin, GL Bashindzhagyan, PF Ermolov, LK Gladilin, YA Golubkov, VD Kobrin, IA Korzhavina, VA Kuzmin, O Yu, AS Proskuryakov, AA Savin, LM Shcheglova, AN Solomin, NP Zotov, M Botje, F Chlebana, J Engelen, M deKamps, P Kooijman, A Kruse, A vanSighem, H Tiecke, W Verkerke, J Vossebeld, M Vreeswijk, L Wiggers, E deWolf, R vanWoudenberg, D Acosta, B Bylsma, LS Durkin, J Gilmore, C Li, TY Ling, P Nylander, JH Park, TA Romankowski, DS Bailey, RJ Cashmore, AM CooperSarkar, RCE Devenish, N Harnew, M Lancaster, L Lindemann, JD McFall, C Nath, VA Noyes, A Quadt, JR Tickner, H Uijterwaal, R Walczak, DS Waters, FF Wilson, T Yip, A Bertolin, R Brugnera, R Carlin, F DalCorso, M DeGiorgi, U Dosselli, S Limentani, M Morandin, M Posocco, L Stanco, R Stroili, C Voci, F Zuin, J Bulmahn, RG Feild, BY Oh, JJ Whitmore, G DAgostini, G Marini, A Nigro, E Tassi, JC Hart, NA McCubbin, TP Shah, E Barberis, T Dubbs, C Heusch, M VanHook, W Lockman, JT Rahn, HFW Sadrozinski, A Seiden, DC Williams, J Biltzinger, RJ Seifert, O Schwarzer, AH Walenta, G Zech, H Abramowicz, G Briskin, S Dagan, A Levy, JI Fleck, M Inuzuka, T Ishii, M Kuze, S Mine, M Nakao, I Suzuki, K Tokushuku, K Umemori, S Yamada, Y Yamazaki, M Chiba, R Hamatsu, T Hirose, K Homma, S Kitamura, T Matsushita, K Yamuchi, R Cirio, M Costa, MI Ferrero, S Maselli, C Peroni, R Sacchi, A Solano, A Staiano, M Dardo, DC Bailey, F Benard, M Brkic, CP Fagerstroem, GF Hartner, KK Joo, GM Levman, JF Martin, RS Orr, S Polenz, CR Sampson, D Simmons, RJ Teuscher, JM Butterworth, CD Catterall, TW Jones, PB Kaziewicz, JB Lane, RL Saunders, J Shulman, MR Sutton, B Lu, LW Mo, W Bogusz, J Ciborowski, J Gajewski, G Grzelak, M Kasprzak, M Krzyzanowski, K Muchorowski, RJ Nowak, JM Pawlak, T Tymieniecka, AK Wroblewski, JA Zakrzewski, AF Zarnecki, C Coldewey, Y Eisenberg, D Hochman, U Karshon, D Revel, D ZerZion, WF Badgett, J Breiweg, D Chapin, RT Cross, S Dasu, C Foudas, RJ Loveless, S Mattingly, DD Reeder, S Silverstein, WH Smith, A Vaiciulis, M Wodarcyk, S Bhadra, ML Cardy, CP Fagerstroem, WR Frisken, KM Furutani, M Khakzad, WN Murray, WB Schmidke

A search for excited fermions in electron-proton collisions at HERA

Zeitschrift für Physik C Particles and Fields 65:4 (1995) 627-647

Authors:

M Derrick, D Krakauer, S Magill, B Musgrave, J Repond, J Schlereth, R Stanek, RL Talaga, J Thron, F Arzarello, R Ayad, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, P Bruni, GC Romeo, G Castellini, M Chiarini, L Cifarelli, F Cindolo, F Ciralli, A Contin, S D'Auria, F Frasconi, I Gialas, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, C Nemoz, F Palmonari, A Polini, G Sartorelli, R Timellini, YZ Garcia, A Zichichi, A Bargende, J Crittenden, K Desch, B Diekmann, T Doeker, M Eckart, L Feld, A Frey, M Geerts, G Geitz, M Grothe, H Hartmann, D Haun, K Heinloth, E Hilger, HP Jakob, UF Katz, SM Mari, A Mass, S Mengel, J Mollen, E Paul, C Rembser, R Schattevoy, JL Schneider, D Schramm, J Stamm, R Wedemeyer, S Campbell-Robson, A Cassidy, N Dyce, B Foster, S George, R Gilmore, GP Heath, HF Heath, TJ Llewellyn, CJS Morgado, DJP Norman, JA O'Mara, RJ Tapper, SS Wilson, R Yoshida, RR Rau, M Arneodo, L Iannotti, M Schioppa, G Susinno, A Bernstein, A Caldwell, JA Parsons, S Ritz, F Sciulli, PB Straub, L Wai, S Yang, P Borzemski, J Chwastowski

Abstract:

A search for excited states of the standard model fermions was performed using the ZEUS detector at the HERA electron-proton collider, operating at a centre of mass energy of 296 GeV. In a sample corresponding to an integrated luminosity of 0.55 pb-1, no evidence was found for any resonant state decaying into final states composed of a fermion and a gauge boson. Limits on the coupling strength times branching ratio of excited fermions are presented for masses between 50 GeV and 250 GeV, extending previous search regions significantly. © 1995 Springer-Verlag.

Measurement of elastic ρ 0 photoproduction at HERA

Zeitschrift für Physik C: Particles and Fields 69:1 (1995) 39-54

Authors:

M Derrick, D Krakauer, S Magill, D Mikunas, B Musgrave, J Repond, R Stanek, RL Talaga, H Zhang, R Ayad, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, P Bruni, G Cara Romeo, G Castellini, M Chiarini, L Cifarelli, F Cindolo, A Contin, M Corradi, I Gialas, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, C Nemoz, F Palmonari, A Polini, G Sartorelli, T Timellini, Y Zamora Garcia, A Zichichi, B Bargende, A Bornheim, J Crittenden, K Desch, B Diekmann, T Doeker, M Eckert, L Feld, A Frey, M Geerts, M Grothe, H Hartmann, K Heinloth, E Hilger, HP Jakob, UF Katz, S Mengel, J Mollen, E Paul, M Pfeiffer, C Rembser, D Schramm, J Stamm, R Wedemeyer, S Campbell-Robson, A Cassidy, N Dyce, B Foster, S George, R Gilmore, GP Heath, HF Heath, TJ Llewellyn, CJS Morgado, DJP Norman, JA O'Mara, RJ Tapper, SS Wilson, R Yoshida, RR Rau, M Arneodo, M Capua, A Garfagnini, L Iannotti, M Schioppa, G Susinno, A Bernstein, A Caldwell, N Cartiglia, JA Parsons, S Ritz, F Sciulli, PB Straub, L Wai, S Yang, Q Zhu, P Borzemski, J Chwastowski, A Eskreys, K Piotrzkowski, M Zachara

Abstract:

Elastic ρ 0 photoproduction has been measured using the ZEUS detector at HERA. Untagged photoproduction events from ep interactions were used to measure the reaction γp→ρ 0 p(ρ 0)→π +π-) at photon-proton centre-of-mass energies between 60 and 80 GeV and |t|<0.5 GeV2, where t is the square of the four-momentum transferred at the proton vertex. The differential cross section dσ/d M ππ where M ππ is the invariant mass of the two pions, and the integrated cross section, σγp→ρ{variant}0ρ{variant}, are presented; the latter was measured to be 14.7±0.4 (stat.) ±2.4 (syst.)μb. The differential cross section dσ/dt has an approximately exponential shape; a fit of the type A t ′ exp(-b t ′ |t|+c t ′ t 2) yields a t-slope b t ′ =9.9±1.2 (stat.) ±1.4 (syst.) GeV-2. The results, when compared to low energy data, show a weak energy dependence of both σγp→ρ{variant}0p and of the t-slope. The ρ 0 is produced predominantly with transverse polarisation, demostrating that s-channel helicity conservation holds at these energies. © 1996 Springer-Verlag.