Running mass of the b-quark in QCD and SUSY QCD

The running mass of the b-quark defined in DRbar-scheme is one of the important parameters of SUSY QCD. To find its value it should be related to some known experimental input. In this paper the b-quark running mass defined in nonsupersymmetric QCD is chosen for determination of corresponding parameter in SUSY QCD. The relation between these two quantities is found by considering five-flavor QCD as an effective theory obtained from its supersymmetric extension. A numerical analysis of the calculated two-loop relation and its impact on the MSSM spectrum is discussed. Since for nonsupersymmetric models MSbar-scheme is more natural than DRbar, we also propose a new procedure that allows one to calculate relations between MSbar- and DRbar-parameters. Unphysical epsilon-scalars that give rise to the difference between mentioned schemes are assumed to be heavy and decoupled in the same way as physical degrees of freedom. By means of this method it is possible to ``catch two rabbits'', i.e., decouple heavy particles and turn from DRbar to MSbar, at the same time. Explicit two-loop example of DRbar -> MSbar transition is given in the context of QCD. The advantages and disadvantages of the method are briefly discussed.Comment: 33 pages, 6 figures, 1 table, typos corrected, added references

Next-to-Next-to-Leading Order Higgs Production at Hadron Colliders

The Higgs boson production cross section at pp and p\bar{p} colliders is calculated in QCD at next-to-next-to-leading order (NNLO). We find that the perturbative expansion of the production cross section is well behaved and that scale dependence is reduced relative to the NLO result. These findings give us confidence in the reliability of the prediction. We also report an error in the NNLO correction to Drell-Yan production.Comment: 5 pages, 4 figures, minor change

Finite top quark mass effects in NNLO Higgs boson production at LHC

We present next-to-next-to-leading order corrections to the inclusive production of the Higgs bosons at the CERN Large Hadron Collider (LHC) including finite top quark mass effects. Expanding our analytic results for the partonic cross section around the soft limit we find agreement with a very recent publication by Harlander and Ozeren \cite{Harlander:2009mq}.Comment: 15 page

Towards Higgs boson production in gluon fusion to NNLO in the MSSM

We consider the Higgs boson production in the gluon-fusion channel to next-to-next-to-leading order within the Minimal Supersymmetric Standard Model. In particular, we present analytical results for the matching coefficient of the effective theory and study its influence on the total production cross section in the limit where the masses of all MSSM particles coincide. For supersymmetric masses below 500 GeV it is possible to find parameters leading to a significant enhancement of the Standard Model cross section, the $K$-factors, however, change only marginally.Comment: 20 pages; v2: modification of discussion of numerical effect, version to appear in EPJC; v3: eq.(18) corrected, minor correction

On the NLO QCD corrections to the production of the heaviest neutral Higgs scalar in the MSSM

We present a calculation of the two-loop top-stop-gluino contributions to Higgs production via gluon fusion in the MSSM. By means of an asymptotic expansion in the heavy particle masses, we obtain explicit and compact analytic formulae that are valid when the Higgs and the top quark are lighter than stops and gluino, without assuming a specific hierarchy between the Higgs mass and the top mass. Being applicable to the heaviest Higgs scalar in a significant region of the MSSM parameter space, our results complement earlier ones obtained with a Taylor expansion in the Higgs mass, and can be easily implemented in computer codes to provide an efficient and accurate determination of the Higgs production cross section.Comment: 18 pages, 4 figure

Higgs production in gluon fusion at next-to-next-to-leading order QCD for finite top mass

The inclusive Higgs production cross section from gluon fusion is calculated through NNLO QCD, including its top quark mass dependence. This is achieved through a matching of the 1/mtop expansion of the partonic cross sections to the exact large s-hat limits which are derived from k_T-factorization. The accuracy of this procedure is estimated to be better than 1% for the hadronic cross section. The final result is shown to be within 1% of the commonly used effective theory approach, thus confirming earlier findings.Comment: 28 pages, 14 figure

Towards precise predictions for Higgs-boson production in the MSSM

We study the production of scalar and pseudoscalar Higgs bosons via gluon fusion and bottom-quark annihilation in the MSSM. Relying on the NNLO-QCD calculation implemented in the public code SusHi, we provide precise predictions for the Higgs-production cross section in six benchmark scenarios compatible with the LHC searches. We also provide a detailed discussion of the sources of theoretical uncertainty in our calculation. We examine the dependence of the cross section on the renormalization and factorization scales, on the precise definition of the Higgs-bottom coupling and on the choice of PDFs, as well as the uncertainties associated to our incomplete knowledge of the SUSY contributions through NNLO. In particular, a potentially large uncertainty originates from uncomputed higher-order QCD corrections to the bottom-quark contributions to gluon fusion.Comment: 62 pages, 24 pdf figures; v2: minor clarifications, improved plot quality, matches published versio

Higgs Production at NNLO

We describe the calculation of inclusive Higgs boson production at hadronic colliders at next-to-next-to-leading order (NNLO) in perturbative quantum chromodynamics. We have used the technique developed in reference [4]. Our results agree with those published earlier in the literature.Comment: Talk given at PASCOS'03, TIFR, Mumbai, LaTeX, 5 page