Inclusiveb-jet andbb¯-dijet production at the LHC via Reggeized gluons

Abstract

We study inclusive $b$-jet and $b\bar b$-dijet production at the CERN LHC invoking the hypothesis of gluon Reggeization in $t$-channel exchanges at high energy. The $b$-jet cross section includes contributions from open $b$-quark production and from $b$-quark production via gluon-to-bottom-pair fragmentation. The transverse-momentum distributions of inclusive $b$-jet production measured with the ATLAS detector at the CERN LHC in different rapidity ranges are calculated both within multi-Regge kinematics and quasi-multi-Regge kinematics. The $b\bar b$-dijet cross-section is calculated within quasi-multi-Regge kinematics as a function of the dijet invariant mass $M_{jj}$, the azimuthal angle between the two jets $\Delta\phi$ and the angular variable $\chi$. At the numerical calculation, we adopt the Kimber-Martin-Ryskin and Bl\"umlein prescriptions to derive unintegrated gluon distribution function of the proton from its collinear counterpart, for which we use the Martin-Roberts-Stirling-Thorne set. We find good agreement with measurements by the ATLAS and CMS Collaborations at the LHC at the hadronic c.m.\ energy of $\sqrt S=7$ TeV.