transverse momentum resummation for higgs production at hadron colliders chong sheng li school of...
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Transverse Momentum Resummation for Higgs Production at Hadron
Colliders
Chong Sheng LiSchool of Physics, Peking University
2012 海峡两岸粒子物理与宇宙学研讨会
2012-05-08, 重庆邮电大学
Based on recent work with J.Wang, H.T. Li, Zhao Li, and C.P.Yuan
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Higgs mechanism: the spontaneous breakdown of a gauge symmetry by a self-interacting scalar field, which thereby lends mass to gauge bosons
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Large Hadron Collider (LHC)
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LHC Results from ATLAS 4.9 fb−1
ATLAS-CONF-2011-163
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LHC Results from CMS 4.8 fb−1
arXiv:1202.1487, arXiv:1202.1997, arXiv:1202.1488
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Status of Higgs Production in the SM• An accurate prediction of the Higgs boson production is crucial to discover or
exclude certain Higgs boson mass regions.
• The main production mechanism of the SM Higgs boson at hadron colliders is gluon fusion through a heavy-quark loop.
1978
LO, Georgi,Glashow
1991,1993,1995 2002
NLO, Dawson,Djouadi,
Spira,Zerwas,
NNLO Harlander,Kilgore,
Anastasiou, Melnikov,
NNLL+NLOpT Resummation, Catani, Grazzini
2005,2007
NNNLL+NNLO Resummation in
SCET, Neubert, L.L.Yang
2008
Differential NNLO, Anastasiou, Melnikov,
Catani, Grazzini
2003-2006
NLL+NLO pT
Resummation in SCET
2008-now
NNLL+NNLO pT Resummation
our work
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pT Resummation in SCETRecently, the soft-collinear effective theory (SCET) has been used widely to discuss the transverse momentum distribtution.
PRD 72,114020(2005)
Y.Gao,C.S.Li,J.Liu No numerical results NLL
PLB625 (2005)253 A.Idilbi,X.Ji,F.Yuan No numerical results NLL
PRD 83,053007(2011)
S. Mantry,F.Petriello Has numerical results for Higgs production
NLL
EPJC(2011)71:1665 T. Becher, M.Neubert Has numerical results for Z production
NNLL
arXiv:1111.4996 M. Garcia, A. Idilbi,… No numerical results NLL
arXiv:1202.0814 J. Chiu, A.Jain,... No numerical results NLL
Collinear Anomaly Rapidity Renormalization Group
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Transverse momentum distribtution
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ResBos: Resummation for Bosons• ResBos can calculate the resummed soft gluon contributions in unpolarized
Drell-Yan-like processes at hadron-hadron colliders.
• ResBos is a useful tool for studying electroweak gauge bosons and Higgs bosons at the Tevatron and the LHC.
• ResBos includes not only QCD resummation for low qT region but also higher order effect in high qT region, with spin correlations included via gauge invariant set of matrix elements.
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Soft Gluon Resummation• In hadron colliders, if the final states are colorless,
the transverse momentum of them vanish due to total momentum conservation. The cross section can be well predicted by fixed-order perturbative calculations.
• But in the small qT region, the fixed-order is not reliable any more since it suffers from the large soft gluon radiation contributions.
Resummation is to resum systematically these large contributions to all orders.
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Soft Gluon Resummation FormulaThe resummation formula for inclusive differential cross section for gg → H can be written as
Born cross sectionQuark mass effects Narrow width approximation
Containing large logarithms Matching termNon-perturbative effects
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Soft Gluon Resummation FormulaThe dominant effects at small qT are encoded in
C function
where the S denote the Sudakov exponent controlled by A, B functions,
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Soft Gluon Resummation FormulaTo obtain the C function, we use the equation
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Soft Gluon Resummation Formula
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Soft Gluon Resummation Formula
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Notice
From virtual corrections
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Soft Gluon Resummation FormulaA G function similar to the C function is also included in ResBos this time.
with
This function appears only for the gluon initiated process.
S. Catani, Nucl.Phys. B845, 297 (2011)
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Total Cross Section for gg → H
Increase by 8% (6%) Agree in 3%, but small uncertainty
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pT distribution of Higgs
enhanced by 20% suppressed by 20%
Here
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Effects of including G functions
The difference is small
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Non-perturbative Coefficients Uncertainty
The uncertainty is obvious only in the small qT region
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Summary