Photoproduction of D*± mesons associated with a leading neutron
Physics Letters Section B Nuclear Elementary Particle and High Energy Physics 590:3-4 (2004) 143-160
Authors:
S Chekanov, M Derrick, D Krakauer, JH Loizides, S Magill, S Miglioranzi, B Musgrave, J Repond, R Yoshida, MCK Mattingly, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, L Cifarelli, F Cindolo, A Contin, M Corradi, S de Pasquale, P Giusti, G Iacobucci, A Margotti, A Montanari, R Nania, F Palmonari, A Pesci, G Sartorelli, A Zichichi, G Aghuzumtsyan, D Bartsch, I Brock, S Goers, H Hartmann, E Hilger, P Irrgang, HP Jakob, O Kind, U Meyer, E Paul, J Rautenberg, R Renner, A Stifutkin, J Tandler, KC Voss, M Wang, A Weber, DS Bailey, NH Brook, JE Cole, GP Heath, T Namsoo, S Robins, M Wing, M Capua, A Mastroberardino, M Schioppa, G Susinno, JY Kim, YK Kim, JH Lee, IT Lim, MY Pac, A Caldwell, M Helbich, X Liu, B Mellado, Y Ning, S Paganis, Z Ren, WB Schmidke, F Sciulli, J Chwastowski, A Eskreys, J Figiel, A Galas, K Olkiewicz, P Stopa, L Zawiejski, L Adamczyk, T Bold, I Grabowska-Bold, D Kisielewska, AM Kowal, M Kowal, T Kowalski, M Przybycień, L Suszycki, D Szuba, J Szuba, A Kotański, W Slomiński, V Adler, U Behrens, I Bloch, K Borras, V Chiochia
Abstract:
The photoproduction of D
*±(2010) mesons associated with a leading neutron has been observed with the ZEUS detector in ep collisions at HERA using an integrated luminosity of 80 pb
-1. The neutron carries a large fraction, x
L>0.2, of the incoming proton beam energy and is detected at very small production angles, θ
n< 0.8 mrad, an indication of peripheral scattering. The D
* meson is centrally produced with pseudorapidity η<1.5, and has a transverse momentum p
T>1.9 GeV, which is large compared to the average transverse momentum of the neutron of 0.22 GeV. The ratio of neutron-tagged to inclusive D
* production is 8.85±0.93(stat.)
+0.48-0.61(syst.)% in the photon-proton center-of-mass energy range 130
Search for QCD-instanton induced events in deep inelastic ep scattering at HERA
European Physical Journal C 34:3 (2004) 255-265
Authors:
S Chekanov, M Derrick, D Krakauer, JH Loizides, S Magill, S Miglioranzi, B Musgrave, J Repond, R Yoshida, MCK Mattingly, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, L Cifarelli, F Cindolo, A Contin, M Corradi, S De Pasquale, P Giusti, G Iacobucci, A Margotti, A Montanari, R Nania, F Palmonari, A Pesci, G Sartorelli, A Zichichi, G Aghuzumtsyan, D Bartsch, I Brock, S Goers, H Hartmann, E Hilger, P Irrgang, HP Jakob, O Kind, U Meyer, E Paul, J Rautenberg, R Renner, A Stifutkin, J Tandler, KC Voss, M Wang, A Weber, DS Bailey, NH Brook, JE Cole, GP Heath, T Namsoo, S Robins, M Wing, M Capua, A Mastroberardino, M Schioppa, G Susinno, JY Kim, YK Kim, JH Lee, IT Lim, MY Pac, A Caldwell, M Helbich, X Liu, B Mellado, Y Ning, S Paganis, Z Ren, WB Schmidke, F Sciulli, J Chwastowski, A Eskreys, J Figiel, A Galas, K Olkiewicz, P Stopa, L Zawiejski, L Adamczyk, T Bold, I Grabowska-Bold, D Kisielewska, AM Kowal, M Kowal, T Kowalski, M Przybycień, L Suszycki, D Szuba, J Szuba, A Kotański, W Slomiński, V Adler, U Behrens, I Bloch, K Borras, V Chiochia
Abstract:
A search for QCD-instanton-induced events in deep inelastic ep scattering has been performed with the ZEUS detector at the HERA collider, using data corresponding to an integrated luminosity of 38 pb-1. A kinematic range defined by cuts on the photon virtuality, Q2 > 120 GeV 2, and on the Bjorken scaling variable, x > 10-3, has been investigated. The QCD-instanton induced events were modelled by the Monte Carlo generator QCDINS. A background-independent, conservative 95% confidence level upper limit for the instanton cross section of 26 pb is obtained, to be compared with the theoretically expected value of 8.9pb.
Bose-Einstein correlations in one and two dimensions in deep inelastic scattering
Physics Letters Section B Nuclear Elementary Particle and High Energy Physics 583:3-4 (2004) 231-246
Authors:
S Chekanov, M Derrick, D Krakauer, JH Loizides, S Magill, S Miglioranzi, B Musgrave, J Repond, R Yoshida, MCK Mattingly, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, L Cifarelli, F Cindolo, A Contin, M Corradi, S De Pasquale, P Giusti, G Iacobucci, A Margotti, A Montanari, R Nania, F Palmonari, A Pesci, G Sartorelli, A Zichichi, G Aghuzumtsyan, D Bartsch, I Brock, S Goers, H Hartmann, E Hilger, P Irrgang, HP Jakob, O Kind, U Meyer, E Paul, J Rautenberg, R Renner, A Stifutkin, J Tandler, KC Voss, M Wang, A Weber, DS Bailey, NH Brook, JE Cole, GP Heath, T Namsoo, S Robins, M Wing, M Capua, A Mastroberardino, M Schioppa, G Susinno, JY Kim, YK Kim, JH Lee, IT Lim, MY Pac, A Caldwell, M Helbich, X Liu, B Mellado, Y Ning, S Paganis, Z Ren, WB Schmidke, F Sciulli, J Chwastowski, A Eskreys, J Figiel, A Galas, K Olkiewicz, P Stopa, L Zawiejski, L Adamczyk, T Bold, I Grabowska-Bold, D Kisielewska, AM Kowal, M Kowal, T Kowalski, M Przybycien, L Suszycki, D Szuba, J Szuba, A Kotanski, W Slominski, V Adler, U Behrens, I Bloch, K Borras, V Chiochia
Abstract:
Bose-Einstein correlations in one and two dimensions have been studied in deep inelastic ep scattering events measured with the ZEUS detector at HERA using an integrated luminosity of 121 pb-1. The correlations are independent of the virtuality of the exchanged photon, Q2, in the range 0.1 < Q2 < 8000 GeV2. There is no significant difference between the correlations in the current and target regions of the Breit frame for Q2 > 100 GeV2. The two-dimensional shape of the particle-production source was investigated, and a significant difference between the transverse and the longitudinal dimensions of the source is observed. This difference also shows no Q2 dependence. The results demonstrate that Bose-Einstein interference, and hence the size of the particle-production source, is insensitive to the hard subprocess. © 2004 Published by Elsevier B.V.
Isolated tau leptons in events with large missing transverse momentum at HERA
Physics Letters Section B Nuclear Elementary Particle and High Energy Physics 583:1-2 (2004) 41-58
Authors:
S Chekanov, M Derrick, D Krakauer, JH Loizides, S Magill, S Miglioranzi, B Musgrave, J Repond, R Yoshida, MCK Mattingly, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, L Cifarelli, F Cindolo, A Contin, M Corradi, S De Pasquale, P Giusti, G Iacobucci, A Margotti, A Montanari, R Nania, F Palmonari, A Pesci, G Sartorelli, A Zichichi, G Aghuzumtsyan, D Bartsch, I Brock, S Goers, H Hartmann, E Hilger, P Irrgang, HP Jakob, O Kind, U Meyer, E Paul, J Rautenberg, R Renner, A Stifutkin, J Tandler, KC Voss, M Wang, A Weber, DS Bailey, NH Brook, JE Cole, GP Heath, T Namsoo, S Robins, M Wing, M Capua, A Mastroberardino, M Schioppa, G Susinno, JY Kim, YK Kim, JH Lee, IT Lim, MY Pac, A Caldwell, M Helbich, X Liu, B Mellado, Y Ning, S Paganis, Z Ren, WB Schmidke, F Sciulli, J Chwastowski, A Eskreys, J Figiel, A Galas, K Olkiewicz, P Stopa, L Zawiejski, L Adamczyk, T Bold, I Grabowska-Bold, D Kisielewska, AM Kowal, M Kowal, T Kowalski, M Przybycień, L Suszycki, D Szuba, J Szuba, A Kotanski, W Slominski, V Adler, U Behrens, I Bloch, K Borras, V Chiochia
Abstract:
A search for events containing isolated tau leptons and large missing transverse momentum, not originating from the tau decay, has been performed with the ZEUS detector at the electron-proton collider HERA, using 130 pb -1 of integrated luminosity. A search was made for isolated tracks coming from hadronic tau decays. Observables based on the internal jet structure were exploited to discriminate between tau decays and quark- or gluon-induced jets. Three tau candidates were found, while 0.40 -0.13+0.12 were expected from Standard Model processes, such as charged current deep inelastic scattering and single W ±-boson production. To search for heavy-particle decays, a more restrictive selection was applied to isolate tau leptons produced together with a hadronic final state with high transverse momentum. Two candidate events survive, while 0.20±0.05 events are expected from Standard Model processes. © 2004 Published by Elsevier B.V.
High-Q2 neutral current cross sections in e+ p deep inelastic scattering at √s = 318 GeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 70:5 (2004)
Authors:
S Chekanov, M Derrick, D Krakauer, JH Loizides, S Magill, S Miglioranzi, B Musgrave, J Repond, R Yoshida, MCK Mattingly, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, L Cifarelli, F Cindolo, A Contin, M Corradi, S de Pasquale, P Giusti, G Iacobucci, A Margotti, A Montanari, R Nania, F Palmonari, A Pesci, G Sartorelli, A Zichichi, G Aghuzumtsyan, D Bartsch, I Brock, S Goers, H Hartmann, E Hilger, P Irrgang, HP Jakob, A Kappes, O Kind, U Meyer, E Paul, J Rautenberg, R Renner, H Schnurbusch, A Stifutkin, J Tandler, KC Voss, M Wang, A Weber, DS Bailey, NH Brook, JE Cole, GP Heath, T Namsoo, S Robins, M Wing, M Capua, A Mastroberardino, M Schioppa, G Susinno, JY Kim, YK Kim, JH Lee, IT Lim, MY Pac, A Caldwell, M Helbich, X Liu, B Mellado, Y Ning, S Paganis, Z Ren, WB Schmidke, F Sciulli, J Chwastowski, A Eskreys, J Figiel, A Galas, K Olkiewicz, P Stopa, L Zawiejski, L Adamczyk, T Bold, I Grabowska-Bold, D Kisielewska, AM Kowal, M Kowal, T Kowalski, M Przybycień, L Suszycki, D Szuba, J Szuba, A Kotański, W Slomiński, V Adler, U Behrens, I Bloch
Abstract:
Cross sections for e+ p neutral current deep inelastic scattering have been measured at a center-of-mass energy of √s = 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 63.2 pb -1. The double-differential cross section, d2σ/ dxdQ2, is presented for 200 GeV2 < Q2 < 30 000 GeV2 and for 0.005 < x < 0.65. The single-differential cross sections dσ/dQ2, dσ/dx and dσ/dy are presented for Q2 > 200 GeV2. The effect of Z-boson-exchange is seen in dσ/dx measured for Q2 > 10 000 GeV2. The data presented here were combined with ZEUS e+ p neutral current data taken at √s = 300 GeV and the structure function F2em was extracted. All results agree well with the predictions of the Standard Model.
