Measurement of dijet production in neutral current deep inelastic scattering at high Q 2 and determination of α s ZEUS

Dijet production has been studied in neutral current deep inelastic ep scattering for 470 < Q < 20000 GeV with the ZEUS detector at HERA using an integrated luminosity of 38.4 pb. Dijet differential cross sections are presented in a kinematic region where both theoretical and experimental uncertainties are small. Next-to-leading-order (NLO) QCD calculations describe the measured differential cross sections well. A QCD analysis of the measured dijet fraction as a function of Q allows both a precise determination of αs(MZ) and a test of the energy-scale dependence of the strong coupling constant. A detailed analysis provides an improved estimate of the uncertainties of the NLO QCD cross sections arising from the parton distribution functions of the proton. The value of αs(MZ), as determined from the QCD fit, is αs(MZ) = 0.1166± 0.0019 (stat.) −0.0033 (exp.) +0.0057 −0.0044 (th.). The ZEUS Collaboration J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, B. Musgrave, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida Argonne National Laboratory, Argonne, IL, USA p M.C.K. Mattingly Andrews University, Berrien Springs, MI, USA 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, T. Massam, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli, A. Zichichi University and INFN Bologna, Bologna, Italy f G. Aghuzumtsyan, C. Amelung, I. Brock, K. Coböken, S. Goers, H. Hartmann, K. Heinloth, E. Hilger, P. Irrgang, H.-P. Jakob, A. Kappes, U.F. Katz, R. Kerger, O. Kind, E. Paul, J. Rautenberg, H. Schnurbusch, A. Stifutkin, J. Tandler, K.C. Voss, A. Weber, H. Wieber Physikalisches Institut der Universität Bonn, Bonn, Germany c D.S. Bailey, O. Barret, N.H. Brook, J.E. Cole, B. Foster, G.P. Heath, H.F. Heath, S. Robins, E. Rodrigues, J. Scott, R.J. Tapper H.H. Wills Physics Laboratory, University of Bristol, Bristol, U.K. o M. Capua, A. Mastroberardino, M. Schioppa, G. Susinno Calabria University, Physics Dept.and INFN, Cosenza, Italy f H.Y. Jeoung, J.Y. Kim, J.H. Lee, I.T. Lim, K.J. Ma, M.Y. Pac Chonnam National University, Kwangju, Korea h A. Caldwell, W. Liu, X. Liu, B. Mellado, S. Paganis, S. Sampson, W.B. Schmidke, F. Sciulli Columbia University, Nevis Labs., Irvington on Hudson, N.Y., USA q J. Chwastowski, A. Eskreys, J. Figiel, K. Klimek, K. Olkiewicz, M.B. Przybycień, P. Stopa, L. Zawiejski Inst. of Nuclear Physics, Cracow, Poland j B. Bednarek, K. Jeleń, D. Kisielewska, A.M. Kowal, T. Kowalski, M. Przybycień, E. Rulikowska-Zarȩbska, L. Suszycki, D. Szuba Faculty of Physics and Nuclear Techniques, Academy of Mining and Metallurgy, Cracow, Poland j A. Kotański Jagellonian Univ., Dept. of Physics, Cracow, Poland