The production of vector boson tagged heavy quark jets provides potentially new tools to study jet quenching, especially the mass hierarchy of parton energy loss. In this work, we present the first theoretical study on $Z^0,+,$b-jet in heavy-ion collisions. Firstly utilizing a Monte Carlo transport model, our simulations give nice descriptions of the azimuthal angle correlation $Deltaphi_{jZ}$, transverse momentum imbalance $x_{jZ}$ for $Z^0,+,$jet as well as the nuclear modification factor $R_{AA}$ of inclusive b-jet in Pb+Pb collisions. Then we calculate the azimuthal angular correlation $Deltaphi_{bZ}$ of $Z^0,+,$b-jet and $Deltaphi_{bb}$ of $Z^0,+,2,$b-jets in central Pb+Pb collisions at $sqrt{s_{NN}}=$~5.02 TeV. We find that the medium modification of the azimuthal angular correlation for $Z^0,+,$b-jet has a weaker dependence on $Deltaphi_{bZ}$, as compared to that for $Z^0,+,$jet. With the high purity of quark jet in $Z^0,+,$(b-)jet production, we calculate the momentum imbalance distribution of $x_{bZ}$ of $Z^0,+,$b-jet in Pb+Pb collisions. We observe a smaller shifting of the mean value of momentum imbalance for $Z^0,+,$b-jet in Pb+Pb collisions $Deltaleftlangle x_{bZ} rightrangle$, as compared to that for $Z^0,+,$jet. In addition, we investigate the nuclear modification factors of tagged jet cross sections $I_{AA}$, and show a much stronger suppression of $I_{AA}$ in $Z^0,+,$jet than that of $Z^0,+,$b-jet in central Pb+Pb collisions.
The production of a W boson and two jets, at least one of which contains a b quark, is a principal background to single-top production, Higgs production, and signals of new physics at hadron colliders. We present a next-to-leading-order (NLO) calculation of the cross section at the Fermilab Tevatron and the CERN Large Hadron Collider. The NLO cross section differs substantially from that at LO, and we provide a context in which to understand this result.
The leading-order process for the production of a Z boson and a heavy-quark jet at hadron colliders is gQ -> ZQ (Q=c,b). We calculate this cross section at next-to-leading order at the Tevatron and the LHC, and compare it with other sources of ZQ events. This process is a background to new physics, and can be used to measure the heavy-quark distribution function.
We calculate the production of a W boson in association with up to two jets including at least one b-jet to next-to-leading order (NLO) in QCD at the CERN Large Hadron Collider with 7 TeV center-of-mass energy. Both exclusive and inclusive event cross section and b-jet cross sections are presented. The calculation is performed consistently in the five-flavor-number scheme where both q anti-q and bq (q == b) initiated parton level processes are included at NLO QCD. We study the residual theoretical uncertainties of the NLO predictions due to the renormalization and factorization scale dependence, to the uncertainty from the parton distribution functions, and to the values of alpha_s and the bottom-quark mass.