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Search for contact interactions, large extra dimensions and finite quark radius in ep collisions at HERA

ArXiv hep-ex/0401009 (2004)
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High-Q^2 neutral current cross sections in e^+p deep inelastic scattering at sqrt{s}=318 GeV

ArXiv hep-ex/0401003 (2004)
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Direct photon cross section with conversions at CDF

Physical Review D - Particles, Fields, Gravitation and Cosmology 70:7 (2004)

Authors:

D Acosta, T Affolder, MG Albrow, D Ambrose, D Amidei, K Anikeev, J Antos, G Apollinari, T Arisawa, A Artikov, W Ashmanskas, F Azfar, P Azzi-Bacchetta, N Bacchetta, H Bachacou, W Badgett, 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, A Beretvas, A Bhatti, M Binkley, D Bisello, M Bishai, RE Blair, C Blocker, K Bloom, B Blumenfeld, A Bocci, A Bodek, G Bolla, A Bolshov, D Bortoletto, J Boudreau, C Bromberg, E Brubaker, J Budagov, HS Budd, K Burkett, G Busetto, KL Byrum, S Cabrera, M Campbell, W Carithers, D Carlsmith, A Castro, D Cauz, A Cerri, L Cerrito, J Chapman, C Chen, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, ML Chu, JY Chung, WH Chung, YS Chung, CI Ciobanu, AG Clark, M Coca, A Connolly, M Convery, J Conway, M Cordelli, J Cranshaw, R Culbertson, D Dagenhart, S D'Auria, P Barbaro, S Cecco, S Dell'Agnello, M Dell'Orso, S Demers, L Demortier, M Deninno, D Pedis, PF Derwent, C Dionisi, JR Dittmann, A Dominguez, S Donati, M D'Onofrio, T Dorigo, N Eddy, R Erbacher, D Errede, S Errede

Abstract:

We present a measurement of the isolated direct photon cross section in [Formula Presented] collisions at [Formula Presented] and [Formula Presented] using data collected between 1994 and 1995 by the Collider Detector at Fermilab (CDF). The measurement is based on events where the photon converts into an electron-positron pair in the material of the inner detector, resulting in a two track event signature. To remove [Formula Presented] and [Formula Presented] events from the data we use a new background subtraction technique which takes advantage of the tracking information available in a photon conversion event. We find that the shape of the cross section as a function of photon [Formula Presented] is poorly described by next-to-leading-order QCD predictions, but agrees with previous CDF measurements. © 2004 The American Physical Society.
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Heavy flavor properties of jets produced in pp̄ interactions at √s = 1.8 TeV

Physical Review D 69:7 (2004)

Authors:

D Acosta, D Ambrose, K Anikeev, J Antos, G Apollinari, T Arisawa, A Artikov, F Azfar, P Azzi-Bacchetta, N Bacchetta, VE Barnes, BA Barnett, M Barone, G Bauer, F Bedeschi, S Behari, S Belforte, WH Bell, G Bellettini, J Bellinger, A Beretvas, A Bhatti, D Bisello, C Blocker, B Blumenfeld, A Bocci, G Bolla, A Bolshov, D Bortoletto, J Budagov, HS Budd, K Burkett, G Busetto, S Cabrera, W Carithers, D Carlsmith, R Carosi, A Castro, D Cauz, A Cerri, C Chen, YC Chen, G Chiarelli, G Chlachidze, ML Chu, WH Chung, YS Chung, AG Clark, M Coca, M Convery, M Cordelli, J Cranshaw, D Dagenhart, S D'Auria, S Dell'Agnello, P de Barbaro, S de Cecco, M Dell'Orso, L Demortier, M Deninno, D de Pedis, C Dionisi, S Donati, M D'Onofrio, T Dorigo, R Eusebi, S Farrington, JP Fernandez, RD Field, I Fiori, A Foland, LR Flores-Castillo, M Franklin, J Friedman, I Furic, M Gallinaro, AF Garfinkel, E Gerstein, S Giagu, P Giannetti, K Giolo, M Giordani, P Giromini, V Glagolev, G Gomez, I Gorelov, AT Goshaw, K Goulianos, A Gresele, M Guenther, J Guimaraes da Costa, E Halkiadakis, C Hall, R Handler, F Happacher, K Hara, F Hartmann, K Hatakeyama, J Hauser, J Heinrich

Abstract:

We present a detailed examination of the heavy flavor properties of jets produced at the Fermilab Tevatron collider. The data set, collected with the Collider Detector at Fermilab, consists of events with two or more jets with transverse energy ET≥15 GeV and pseudorapidity |η|≤1.5. The heavy flavor content of the data set is enriched by requiring that at least one of the jets (lepton-jet) contains a lepton with a transverse momentum larger than 8 GeV/c. Jets containing hadrons with heavy flavor are selected via the identification of secondary vertices. The parton-level cross sections predicted by the HERWIG Monte Carlo generator program are tuned within theoretical and experimental uncertainties to reproduce the secondary-vertex rates in the data. The tuned simulation provides new information on the origin of the discrepancy between the bb̄ cross section measurements at the Tevatron and the next-to-leading order QCD prediction. We also compare the rate of away-jets (jets recoiling against the lepton-jet) containing a soft lepton (p T≥2 GeV/c) in the data to that in the tuned simulation. We find that this rate is larger than what is expected for the conventional production and semileptonic decay of pairs of hadrons with heavy flavor. © 2004 The American Physical Society.
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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.
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