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Higgs+jets
Higgs+jets

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data vs theory Joey Huston Bruce Mellado 1 Higgsgt gg jets Most of the excess observed for Higgs production is in gt1 jet final states Maybe CMS does not see as large of an excess ID: 324385 Download Presentation

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Slide1

Higgs+jets: data vs theory

Joey HustonBruce Mellado

1Slide2

Higgs(->gg)+jets

Most of the excess observed for Higgs production is in >=1 jet final statesMaybe 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 calculationwhich means a NLO calculation for Higgs + 1 jetand a LO calculation for Higgs + 2 jets

2Slide3

NNNLO inclusive

gg->Higgs cross section is not very convergentSo 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

p

assed on to the 1 and 2

j

et cross sections as well

3Slide4

Higgs+1 jet at NLO

…from Dec. 20 meetingNLO cross section has a LO-like scale dependence

4Slide5

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)

σ

NLO

/

σ

LO

= 1.6

σ

NNLO

/

σ

NLO

= 1.3

arXiv:1302.6216

5Slide6

Higgs+jets (binned cross sections)

r

esummation

for Higgs + 0 jet

and for Higgs + 1 jet has lead

to sizeable reduction in scaleuncertainty for exclusive Higgs

+0,1 jet production

w

e need to revisit the formulation of the

u

ncertainties for binned jet Higgs cross

s

ections

t

his is a task for Snowmass/

Les

Houches

a

lso investigate jet veto effects for higher

e

nergy accelerators

Xiaohui

LiuSlide7

What about Higgs+>=2 jet final states?

We know Higgs+2 jets to NLOA 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

7Slide8

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 usingOne 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 predictionsI have Higgs+1 jet (at NLO) working now, and should have Higgs+2 jets in the next few days

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.

2

nd

jet

r

eceives

s

ubstantial

c

ontributions

f

rom 3-jet

m

atrix

element

8

Shom More....
By: myesha-ticknor
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