 TWiki> LHCPhysics Web>LHCHXSWG>LHCHXSWG1>LHCHXSWGHiggsJets (revision 7)

# Jets subgroup

## Group Contacts

Daniele del Re (CMS)

Gavin Salam (Theory)

Frank Tackmann (Theory)

## Settings for comparison studies

### H+2-jet NLO+shower comparison study

Process/Inputs:
===============

* pure gg -> H + 2j NLO+shower at parton level

* m_H = 125 GeV
* \sqrt{s} = 8 TeV
* strict mtop -> \infty limit (no mtop rescaling or bottom interference)
* on-shell stable Higgs
* MSTW2008 NLO PDFs (68CL) (always also at LO)
with its alphas(mZ) = 0.12018, nf = 5, 2-loop running
* \mu_r = \mu_f = \mu = m_H in (N)LO hard matrix element corrections

Jet cuts:
=========

(\eta is pseudorapidity, y is rapidity)

a) Jet selection:
* anti-kT with R = 0.4
* at least two jets with pTj > 25 GeV and |\eta_j| < 5

b) VBF cuts:
* \delta y_jj = |y_j1 - y_j2| > 2.8
* m_jj > 400 GeV

Distributions:
==============

All distributions with
* only cuts a) and cuts a)+b)
* at LO and NLO each with \mu = {2 m_H, m_H, m_H/2}

1) pTj1 [0, 300] in steps of 5 GeV
2) pTj2  [0, 300] in steps of 5 GeV
3) yj1 [-5, 5] in steps of 0.5
4) yj2 [-5, 5] in steps of 0.5
5) |\delta\y_jj| [0,10] in steps of 0.5
6) m_jj [0, 1000] in steps of 40 GeV

7) \Delta\phi_jj [0, Pi] in steps of Pi/20
8) pTj3 [0, 300] in steps of 5 GeV
9) yj3 [-5, 5] in steps of 0.5

10) |eta_H - 0.5(\eta_j1 + \eta_j2)| [0,10] in steps of 0.5
11) pT_{Hjj} = |\vec{p}_{TH} + \vec{p}_{Tj1} + \vec{p}_{Tj2}| [0, 300] in steps of 5 GeV
12) Pi - \Delta\phi_{H,jj} [0, 1.5] in steps of 0.05

## Results

First comparisons can be found here .

## Guidelines for UE related uncertainties

The following are guidelines for the estimation of UE related uncertainties in ggF and VBF processes:

1) Turn UE on/off for the nominal default tune (expect ~10-20% variations depending on selection cuts and tune)

2) Cross check on/off effect for alternative tunes (that are also deemed "reasonable")

3) Cross checks can include the use of tunes performed within a common framework but using different PDFs (eg. NLO v. LO, as is the case with AU2-CT10 and AU2-CTEQ6L1)

First studies can be found here and these studies will continue past the Moriond conferences. Until these guidelines can be implemented, the following temporary uncertainties are suggested:

1) For ggF+2j use 30% uncertainty

2) For VBF use 7% uncertainty

These uncertainties pertain to the normalization of both samples in the loose and tight VBF categories.

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