Measurement of multijet production in collisions at high and determination of the strong coupling

Inclusive jet, dijet and trijet differential crosssections are measured in neutral current deep-inelastic scatteringfor exchanged boson virtualities using the H1 detector at HERA. The data were taken in the years 2003 to 2007 and correspond to an integrated luminosity of . Double differential Jet crosssections are obtained using a regularised unfolding procedure. They are presented as a function of and the transverse momentum of the jet, , and as a function of and the proton’s longitudinal momentum fraction, , carried by the parton participating in the hard interaction. In addition normalised double differential jet crosssections are measured as the ratio of the jet crosssections to the inclusive neutral current crosssections in the respective bins of the jet measurements. Compared to earlier work, the measurements benefit from an improved reconstruction and calibration of the hadronic final state. The crosssections are compared to perturbative QCDcalculations in next-to-leading order and are used to determine the running coupling and the value of the strong coupling constant as .