Higgs production at the LHC: transverse-momentum and rapidity dependence giuseppe bozzi Institut für Theoretische Physik Universität Karlsruhe in collaboration with: Stefano Catani, Daniel de Florian, Massimiliano Grazzini RADCOR 2007 Firenze, 04.10.2007 giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 1 / 19
Outline Overview of recent results for gg → H 1 Total cross section Differential distributions The main ideas of resummation 2 Resummation Exponentiation Matching Numerical results at the LHC 3 Summary 4 giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 2 / 19
Overview of recent results for gg → H Outline Overview of recent results for gg → H 1 Total cross section Differential distributions The main ideas of resummation 2 Resummation Exponentiation Matching Numerical results at the LHC 3 Summary 4 giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 3 / 19
Overview of recent results for gg → H Total cross section Fixed-order perturbative results NLO ( O ( α 3 s ) ): increase LO cross section by about 80-100%! [Dawson(1991)] [Djouadi,Spira,Zerwas(1991)] [Spira,Djouadi,Graudenz,Zerwas(1995)] NNLO ( O ( α 4 s ) ): another 15-20% enhancement ( m t → ∞ ) [Harlander(2000)] [Harlander,Kilgore(2001,2002)] [Catani,deFlorian,Grazzini(2001,2002)] [Anastasiou,Melnikov(2002)] [Ravindran,Smith,vanNeerven(2003)] Bulk of radiative corrections due to virtual and soft-gluon contributions → ( insensitive to top quark loop ) → Large- m t limit works very well (difference < 4% for M H < 200 GeV ) giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 4 / 19
Overview of recent results for gg → H Total cross section Fixed-order perturbative results NLO ( O ( α 3 s ) ): increase LO cross section by about 80-100%! [Dawson(1991)] [Djouadi,Spira,Zerwas(1991)] [Spira,Djouadi,Graudenz,Zerwas(1995)] NNLO ( O ( α 4 s ) ): another 15-20% enhancement ( m t → ∞ ) [Harlander(2000)] [Harlander,Kilgore(2001,2002)] [Catani,deFlorian,Grazzini(2001,2002)] [Anastasiou,Melnikov(2002)] [Ravindran,Smith,vanNeerven(2003)] Bulk of radiative corrections due to virtual and soft-gluon contributions → ( insensitive to top quark loop ) → Large- m t limit works very well (difference < 4% for M H < 200 GeV ) giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 4 / 19
Overview of recent results for gg → H Total cross section Fixed-order perturbative results NLO ( O ( α 3 s ) ): increase LO cross section by about 80-100%! [Dawson(1991)] [Djouadi,Spira,Zerwas(1991)] [Spira,Djouadi,Graudenz,Zerwas(1995)] NNLO ( O ( α 4 s ) ): another 15-20% enhancement ( m t → ∞ ) [Harlander(2000)] [Harlander,Kilgore(2001,2002)] [Catani,deFlorian,Grazzini(2001,2002)] [Anastasiou,Melnikov(2002)] [Ravindran,Smith,vanNeerven(2003)] Bulk of radiative corrections due to virtual and soft-gluon contributions → ( insensitive to top quark loop ) → Large- m t limit works very well (difference < 4% for M H < 200 GeV ) giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 4 / 19
Overview of recent results for gg → H Total cross section Fixed-order perturbative results NLO ( O ( α 3 s ) ): increase LO cross section by about 80-100%! [Dawson(1991)] [Djouadi,Spira,Zerwas(1991)] [Spira,Djouadi,Graudenz,Zerwas(1995)] NNLO ( O ( α 4 s ) ): another 15-20% enhancement ( m t → ∞ ) [Harlander(2000)] [Harlander,Kilgore(2001,2002)] [Catani,deFlorian,Grazzini(2001,2002)] [Anastasiou,Melnikov(2002)] [Ravindran,Smith,vanNeerven(2003)] Bulk of radiative corrections due to virtual and soft-gluon contributions → ( insensitive to top quark loop ) → Large- m t limit works very well (difference < 4% for M H < 200 GeV ) giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 4 / 19
Overview of recent results for gg → H Total cross section Resummed results Higher-order perturbative contributions reliably estimated by resumming multiple soft-gluon emissions NNLL+NNLO: perturbative uncertainty reduced to ± 10% [Catani,deFlorian,Grazzini,Nason(2003)] Soft-gluon terms at NNNLO: effects consistent with NNLL+NNLO uncertainty [Moch,Vogt(2005)] [Laenen,Magnea(2006)] [Idilbi,Ji,Ma,Yuan(2006)] giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 5 / 19
Overview of recent results for gg → H Total cross section Resummed results Higher-order perturbative contributions reliably estimated by resumming multiple soft-gluon emissions NNLL+NNLO: perturbative uncertainty reduced to ± 10% [Catani,deFlorian,Grazzini,Nason(2003)] Soft-gluon terms at NNNLO: effects consistent with NNLL+NNLO uncertainty [Moch,Vogt(2005)] [Laenen,Magnea(2006)] [Idilbi,Ji,Ma,Yuan(2006)] giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 5 / 19
Overview of recent results for gg → H Total cross section Resummed results Higher-order perturbative contributions reliably estimated by resumming multiple soft-gluon emissions NNLL+NNLO: perturbative uncertainty reduced to ± 10% [Catani,deFlorian,Grazzini,Nason(2003)] Soft-gluon terms at NNNLO: effects consistent with NNLL+NNLO uncertainty [Moch,Vogt(2005)] [Laenen,Magnea(2006)] [Idilbi,Ji,Ma,Yuan(2006)] giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 5 / 19
Overview of recent results for gg → H Differential distributions Fixed-order perturbative results Transverse-momentum distribution [Ellis,Hinchliffe,Soldate,vanDerBij(1988)] : LO ( O ( α 3 s ) ) [Baur,Glover(1990)] : LO ( O ( α 3 s ) ) [deFlorian,Grazzini,Kunszt(1999)] : NLO ( O ( α 4 s ) ) [Ravindran,Smith,vanNeerven(2002)] : NLO ( O ( α 4 s ) ) [Glosser,Schmidt(2002)] : NLO ( O ( α 4 s ) ) Fully exclusive results [Anastasiou,Melnikov,Petriello(2004,2005)] : NNLO [Catani,Grazzini(2007)] : NNLO Large- m t approximation still valid if M H < 2 M t , q T < M t Be careful with small- q T region! giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 6 / 19
Overview of recent results for gg → H Differential distributions Fixed-order perturbative results Transverse-momentum distribution [Ellis,Hinchliffe,Soldate,vanDerBij(1988)] : LO ( O ( α 3 s ) ) [Baur,Glover(1990)] : LO ( O ( α 3 s ) ) [deFlorian,Grazzini,Kunszt(1999)] : NLO ( O ( α 4 s ) ) [Ravindran,Smith,vanNeerven(2002)] : NLO ( O ( α 4 s ) ) [Glosser,Schmidt(2002)] : NLO ( O ( α 4 s ) ) Fully exclusive results [Anastasiou,Melnikov,Petriello(2004,2005)] : NNLO [Catani,Grazzini(2007)] : NNLO Large- m t approximation still valid if M H < 2 M t , q T < M t Be careful with small- q T region! giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 6 / 19
Overview of recent results for gg → H Differential distributions Fixed-order perturbative results Transverse-momentum distribution [Ellis,Hinchliffe,Soldate,vanDerBij(1988)] : LO ( O ( α 3 s ) ) [Baur,Glover(1990)] : LO ( O ( α 3 s ) ) [deFlorian,Grazzini,Kunszt(1999)] : NLO ( O ( α 4 s ) ) [Ravindran,Smith,vanNeerven(2002)] : NLO ( O ( α 4 s ) ) [Glosser,Schmidt(2002)] : NLO ( O ( α 4 s ) ) Fully exclusive results [Anastasiou,Melnikov,Petriello(2004,2005)] : NNLO [Catani,Grazzini(2007)] : NNLO Large- m t approximation still valid if M H < 2 M t , q T < M t Be careful with small- q T region! giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 6 / 19
Overview of recent results for gg → H Differential distributions Fixed-order perturbative results Transverse-momentum distribution [Ellis,Hinchliffe,Soldate,vanDerBij(1988)] : LO ( O ( α 3 s ) ) [Baur,Glover(1990)] : LO ( O ( α 3 s ) ) [deFlorian,Grazzini,Kunszt(1999)] : NLO ( O ( α 4 s ) ) [Ravindran,Smith,vanNeerven(2002)] : NLO ( O ( α 4 s ) ) [Glosser,Schmidt(2002)] : NLO ( O ( α 4 s ) ) Fully exclusive results [Anastasiou,Melnikov,Petriello(2004,2005)] : NNLO [Catani,Grazzini(2007)] : NNLO Large- m t approximation still valid if M H < 2 M t , q T < M t Be careful with small- q T region! giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 6 / 19
Overview of recent results for gg → H Differential distributions The small- q T region ( q T ≪ M H ) Bulk of the events in the region q T ≪ M H Kinematical unbalance between real and virtual contributions S log m ( M 2 → perturbative coefficients enhanced by α n T ) H q 2 → convergence of perturbative result completely spoiled → need for resummation! giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 7 / 19
Overview of recent results for gg → H Differential distributions The small- q T region ( q T ≪ M H ) Bulk of the events in the region q T ≪ M H Kinematical unbalance between real and virtual contributions S log m ( M 2 → perturbative coefficients enhanced by α n T ) H q 2 → convergence of perturbative result completely spoiled → need for resummation! giuseppe bozzi (ITP Karlsruhe) SM Higgs production at the LHC Firenze, 04.10.2007 7 / 19
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