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Observation of the strange sea in the proton via inclusive φ-meson production in neutral current deep inelastic scattering at HERA

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 553:3-4 (2003) 141-158

Authors:

S Chekanov, D Krakauer, S Magill, 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, 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, UF Katz, O Kind, E Paul, J Rautenberg, R Renner, H Schnurbusch, A Stifutkin, J Tandler, KC Voss, M Wang, A Weber, DS Bailey, NH Brook, JE Cole, B Foster, GP Heath, HF Heath, S Robins, E Rodrigues, J Scott, RJ Tapper, 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, K Olkiewicz, P Stopa, L Zawiejski, L Adamczyk, T Bołd, I Grabowska-Bołd, D Kisielewska, AM Kowal, M Kowal, T Kowalski, M Przybycień, L Suszycki, D Szuba, J Szuba, A Kotański, W Słomiński, LAT Bauerdick, M Kuze

Abstract:

Inclusive φ(1020)-meson production in neutral current deep inelastic e+p scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 45 pb-1. The φ mesons were studied in the range 10 < Q2 < 100 GeV2, where Q2 is the virtuality of the exchanged photon, and in restricted kinematic regions in the transverse momentum, pT, pseudorapidity, η, and the scaled momentum in the Breit frame, xp. Monte Carlo models with the strangeness-suppression factor as determined by analyses of e+e- annihilation events overestimate the cross sections. A smaller value of the strangeness-suppression factor reduces the predicted cross sections, but fails to reproduce the shapes of the measured differential cross sections. High-momentum φ mesons in the current region of the Breit frame give the first direct evidence for the strange sea in the proton at low x. © 2002 Published by Elsevier Science B.V.
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The Diamond Detector Research Group

Office of Scientific and Technical Information (OSTI) (2003)

Authors:

Steven Worm, J Doroshenko, T Koeth, L Parera, S Schnetzer, R Stone, D Bortoletto, I Shipsey, G Bolla, J Lee, K Arndt, A Roy, S Son
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Study of the azimuthal asymmetry of jets in neutral current deep inelastic scattering at HERA

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics 551:3-4 (2003) 226-240

Authors:

S Chekanov, D Krakauer, S Magill, 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, 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, UF Katz, O Kind, E Paul, J Rautenberg, R Renner, H Schnurbusch, A Stifutkin, J Tandler, KC Voss, M Wang, A Weber, DS Bailey, NH Brook, JE Cole, B Foster, GP Heath, HF Heath, S Robins, E Rodrigues, J Scott, RJ Tapper, M Wing, M Capua, A Mastroberardino, M Schioppa, G Susinno, JY Kim, YK Kim, JH Lee, IT Lim, MY Pac, A Caldwell, M Helblich, X Lui, B Mellado, Y Ning, S Paganis, Z Ren, WB Schmidke, F Sciulli, J Chwastowski, A Eskreys, J Figiel, 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, LAT Bauerdick, U Behrens

Abstract:

The azimuthal distribution of jets produced in the Breit frame in high-Q2 deep inelastic e+p scattering has been studied with the ZEUS detector at HERA using an integrated luminosity of 38.6 pb-1. The measured azimuthal distribution shows a structure that is well described by next-to-leading-order QCD predictions over the Q2 range considered, Q2 > 125 GeV2. © 2002 Elsevier Science B.V. All rights reserved.
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Measurement of proton-dissociative diffractive photoproduction of vector mesons at large momentum transfer at HERA: The ZEUS collaboration

European Physical Journal C 26:3 (2003) 389-409

Authors:

S Chekanov, D Krakauer, S Magill, 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, G Levi, A Margotti, R Nania, F Palmonari, A Pesci, G Sartorelli, A Zichichi, G Aghuzumtsyan, D Bartsch, I Brock, J Crittenden, S Goers, H Hartmann, E Hilger, P Irrgang, HP Jakob, A Kappes, UF Katz, R Kerger, O Kind, E Paul, J Rautenberg, R Renner, H Schnurbusch, A Stifutkin, J Tandler, KC Voss, A Weber, DS Bailey, NH Brook, JE Cole, B Foster, GP Heath, HF Heath, S Robins, E Rodrigues, J Scott, RJ Tapper, 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, S Paganis, WB Schmidke, F Sciulli, J Chwastowski, A Eskreys, J Figiel, K Olkiewicz, K Piotrzkowski, MB Przybycień, P Stopa, L Zawiejski, L Adamczyk, B Bednarek, I Grabowska-Bold, K Jeleń, D Kisielewska, AM Kowal, M Kowal, T Kowalski, B Mindur, E Rulikowska-Zarebska, L Suszycki, D Szuba, J Szuba, A Kotański, W Slomiński

Abstract:

Diffractive photoproduction of vector mesons, γp → VY, where Y is a proton-dissociative system, has been measured in e+p interactions with the ZEUS detector at HERA using an integrated luminosity of 25 pb-1. The differential cross section, dσ/dt, is presented for 1.2 < -t < 12 GeV2, where t is the square of the four-momentum transferred to the vector meson. The data span the range in photon-proton centre-of-mass energy, W, from 80 GeV to 120 GeV. The t distributions are well fit by a power law, dσ/dt ∝ (-t)-n. The slope of the effective Pomeron trajectory, measured from the W dependence of the ρ0 and φ cross sections in bins of t, is consistent with zero. The ratios dσγp→φY/dt to dσγp→ρ0Y/dt and dσγp→J/ψY/dt to dσγp→ρ0Y/dt increase with increasing -t. Decay-angle analyses for ρ0, φ and J/ψ mesons have been carried out. For the ρ0 and φ mesons, contributions from single and double helicity flip are observed. The results are compared to expectations of theoretical models.
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Momentum distribution of charged particles in jets in dijet events in pp collisions at √s=1.8 TeV and comparisons to perturbative QCD predictions

Physical Review D 68:1 (2003)

Authors:

D Acosta, T Affolder, H Akimoto, MG Albrow, D Ambrose, D Amidei, K Anikeev, J Antos, G Apollinari, T Arisawa, A Artikov, T Asakawa, W Ashmanskas, F Azfar, P Azzi-Bacchetta, N Bacchetta, H Bachacou, W Badgett, S Bailey, P De Barbaro, A Barbaro-Galtieri, VE Barnes, BA Barnett, S Baroiant, M Barone, G Bauer, F Bedeschi, S Behari, S Belforte, WH Bell, G Bellettini, J Bellinger, D Benjamin, J Bensinger, A Beretvas, J Berryhill, A Bhatti, M Binkley, D Bisello, M Bishai, RE Blair, C Blocker, K Bloom, B Blumenfeld, SR Blusk, A Bocci, A Bodek, G Bolla, Y Bonushkin, D Bortoletto, J Boudreau, A Brandl, C Bromberg, M Brozovic, E Brubaker, N Bruner, J Budagov, HS Budd, K Burkett, G Busetto, KL Byrum, S Cabrera, P Calafiura, M Campbell, W Carithers, J Carlson, D Carlsmith, W Caskey, A Castro, D Cauz, A Cerri, AW Chan, PS Chang, PT Chang, J Chapman, C Chen, YC Chen, MT Cheng, M Chertok, G Chiarelli, I Chirikov-Zorin, G Chlachidze, F Chlebana, L Christofek, ML Chu, JY Chung, WH Chung, YS Chung, CI Ciobanu, AG Clark, M Coca, AP Colijn, A Connolly, M Convery, J Conway, M Cordelli, J Cranshaw, R Culbertson, D Dagenhart, S D’Auria

Abstract:

Inclusive momentum distributions of charged particles in restricted cones around jet axes were measured in dijet events with invariant dijet masses in the range 80 to 600 GeV/c2. Events were produced at the Fermilab Tevatron in pp collisions with a center of mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The results were compared to perturbative QCD calculations carried out in the framework of the modified leading log approximation (MLLA) and assuming local parton-hadron duality. It was shown that the data follow theoretical predictions quite well over the whole range of the jet energies included in this analysis. We extracted the MLLA cutoff scale Qe f f and found a value of 230±40 MeV. The theoretical prediction of Ejetsin θc scaling, where u c is the cone opening angle, was experimentally observed for the first time. From the MLLA fits to the data, two more parameters were extracted: the ratio of parton multiplicities in gluon and quark jets, r = Npartonsg-jet /Npartonsq-jet = 1.9±0.5, and the ratio of the number of charged hadrons to the number of predicted partons in a jet, KLPHDcharged=Nhadronscharged/Npartons=0.56±0.10.
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