Higgs+jets: data vs theory
Joey Huston
Bruce Mellado
1
Higgs(->gg)+jets
 Most of the excess observed
for Higgs production is in >=1
jet final states
 Maybe CMS does not see as
large of an excess
 In any case, we would like to
use the best theory we can to
understand the level of excess
 For inclusive Higgs production
through gg fusion, we use a
NNLO+NNLL calculation
which means a NLO
calculation for Higgs + 1
jet
and a LO calculation for
Higgs + 2 jets
2
NNNLO inclusive
 gg->Higgs cross section is not very convergent
 So it’s appropriate to think about effects of still higher order corrections
 Approximate NNNLO corrections have been carried out resumming the
effects of soft gluon radiation; recently BFKL logs have been resummed as
well, leading to more scale stability and an additional increase in the cross
section
This increase should be
passed on to the 1 and 2
jet cross sections as well
Higgs+1 jet at NLO
 …from Dec. 20 meeting
 NLO cross section has a LO-like scale dependence
4
Higgs+1 jet at NNLO
 So the NNLO correction for
Higgs+1 jet (through gg
fusion) is about 30%
 gg corresponds to about 65%
of the cross section; they are
working on other initial states
and it is probable that the
NNLO corrections for the
other initial states (gq) will be
somewhat smaller (maybe
1.15 instead of 1.30)
arXiv:1302.6216
σNLO/σLO = 1.6
σNNLO/σNLO = 1.3
5
Higgs+jets (binned cross sections)
Xiaohui Liu
resummation for Higgs + 0 jet
and for Higgs + 1 jet has lead
to sizeable reduction in scale
uncertainty for exclusive Higgs
+0,1 jet production
we need to revisit the formulation of the
uncertainties for binned jet Higgs cross
sections
this is a task for Snowmass/
Les Houches
also investigate jet veto effects for higher
energy accelerators
What about Higgs+>=2 jet final states?
 We know Higgs+2 jets to NLO
 A NNLO calculation of Higgs+2 jets is a long way off, but by general
arguments we might expect the size of the NNLO corrections to be <= that
seen for Higgs+1 jet
7
Sherpa+…
 One of the best vehicles to
estimate contributions to the
different jet multiplicities may be
Sherpa(+gosam/MCFM/blackhat)
 At least it’s the one I’m currently
using
 One can include Higgs+0,1 and 2
jets at NLO, up to 3 additional jets
at LO, with extra jets from parton
showers, looking at the effects of
varying the merging scale, the
renormalization scale, the
factorization scale and the
resummation scale
with maybe some motivated
re-weighting based on the
new theory predictions
 I have Higgs+1 jet (at NLO)
working now, and should have
Higgs+2 jets in the next few days
2nd jet
receives
substantial
contributions
from 3-jet
matrix
element
 The same thing can be done for
W+jets, so this may be a useful
cross-check in a channel where
the statistics are much higher and
the physics perhaps better
understood
 We know we see an excess
 It may be a fluctuation, we would
like to understand the theory
predictions and their
uncertainties.
8