Determination of the Strong Coupling Constant from the Inclusive Jet Cross Section in Deep-Inelastic Positron-Proton Collisions at HERA H1 Collaboration

We have measured the inclusive jet cross section in the Breit frame in deep-inelastic scattering at large four momentum transfers squared Q2 and large transverse jet energies ET using the inclusive k? jet algorithm. The analysis is based on data corresponding to an integrated luminosity of L ' 33 pb 1 taken in the years 1995-1997 with the H1 detector at the positron-proton collider HERA at a center-of-mass energy psep = 300GeV. The inclusive jet cross section is presented double differentially as a function of ET and Q2 in the range 49 < E2 T < 2500GeV2 and 150 < Q2 < 5000GeV2. In a QCD analysis of the data we have determined the strong coupling constant s. Setting the renormalization scale equal to the transverse jet energy, we investigate the running of s(ET ). We present comprehensive studies of the dependence of the results on the parton distributions used in the fit. Finally we have performed a combined fit to the data over the whole range of ET and Q2 and obtain a preliminary result of s(MZ) = 0:1181 0:0030(exp)+0:0039 0:0046(theo)+0:0036 0:0015(parton density functions). We have repeated the analysis setting the renormalization scale to the four momentum transfer r = Q and obtain a preliminary result of s(MZ) = 0:1221 0:0034(exp:)+0:0054 0:0059(theo:)+0:0033 0:0016(pdf) with an increased theoretical uncertainty resulting from a larger renormalization scale dependence. Abstract: 157 Parallel sessions: 1 Plenary sessions: 1 Electronic Access: http://www-h1.desy.de/publications/ 157 Parallel sessions: 1 Plenary sessions: 1 Electronic Access: http://www-h1.desy.de/publications/