close

Вход

Забыли?

вход по аккаунту

?

TEV4LHC211005

код для вставкиСкачать
QCD Higher Order Corrections
in Hп‚®пЃґпЃґ + 1jet at the LHC
B.Mellado, S.Padhi, W.Quayle and Sau Lan Wu
(University of Wisconsin)
Special thanks to J.Campbell, F.Krauss and K.Ellis
TEV4LHC, Higgs Session 10/21/05
Motivation
Hп‚®пЃґпЃґ (ll + lh) +jets are fundamental for an early observation
and robustness of low mass SM Higgs
пѓ� Addressing phenomenological and experimental issues
Bruce Mellado, Higgs WG Meeting 10/21/05
2
We are considering QCD Higher order effects on
analyses with +1jet and +2jets
пѓ� NLO QCD corrections for VBF signal and Z+jets in
H+2jet analysis have been considered in the past
пЃ¶ We are assessing (not reported here) the impact of Z+34jet tree level Matrix Elements on Z+jets after applying
H+2jet analysis cuts. Use ALPGEN/SHERPA
пЃ± Address central jet veto with ALPGEN/SHERPA
пѓ� QCD Higher order corrections have not been evaluated
within the Hп‚®пЃґпЃґ+1jet analysis neither for signal nor for
the Z+jets background
пЃ¶ NLO corrections are evaluated here with MCFM
пЃ¶ We also address the impact of Z+2-3jet tree level ME on
Z+jets using ALPGEN/SHERPA (not reported here)
Bruce Mellado, Higgs WG Meeting 10/21/05
3
Hп‚®пЃґпЃґ Associated
with one hard jet
Bruce Mellado, Higgs WG Meeting 10/21/05
4
Low Mass SM Hп‚®пЃґпЃґ+jets
Reconstruct Higgs mass with collinear approxim.
H(п‚®пЃґпЃґп‚®ll) +п‚і2jets (VBF)
30 fb-1
H(п‚®пЃґпЃґп‚®2l) +п‚і1jet
Hп‚®пЃґпЃґп‚®ll
MH=120 GeV
Bruce Mellado, Higgs WG Meeting 10/21/05
5
1.
2.
3.
SM Higgsп‚®пЃґпЃґ + 1jet
Large invariant mass of leading
jet and Higgs candidate
Large PT of Higgs candidate
Leading jet is more forward
than in QCD background
B.Mellado, W.Quayle and Sau Lan Wu
Phys.Lett.B611:60-65,2005
Higgs Decay Products
Tag jet
Not Tagged
Tag jet
Large
PTH &
MHJ
пЃЄ
Loose Central Jet Veto
(“top killer”)
Bruce Mellado, Higgs WG Meeting 10/21/05
пЃЁ
Quasi-central
Tagging Jet
6
QCD Z+1j production gives about 50% of background
пѓ� Need to evaluate role of QCD higher order corrections
пЃ¶ These are not trivial due to specifics of cuts
Bruce Mellado, Higgs WG Meeting 10/21/05
7
QCD HO Corrections in QCD Z+1jet
LHC
MCFM
Bruce Mellado, Higgs WG Meeting 10/21/05
8
K Factor
LHC
Moderate K factor of
about 1.2 for inclusive
Z+1j production
Bruce Mellado, Higgs WG Meeting 10/21/05
9
Strong effect on PT of leading jet and the invariant
mass of Z and the leading jet
Sherpa
Z+п‚Ј1j ME+PS
Z+п‚Ј2j ME+PS
Bruce Mellado, Higgs WG Meeting 10/21/05
Z+п‚Ј1j ME+PS
Z+п‚Ј2j ME+PS
10
Central jet veto (“top killer”, PTJ<30GeV) significantly
reduces effect of higher order corrections
пѓ� With MZJ>700 GeV Z+1j increases by factor of 2
Z+п‚Ј1j ME+PS
Z+п‚Ј1j ME+PS
Z+п‚Ј2j ME+PS
Z+п‚Ј2j ME+PS
Bruce Mellado, Higgs WG Meeting 10/21/05
11
QCD NLO Corrections to H+1j
K-factors are strong for large PTH and MHJ
NLO
LO
Bruce Mellado, Higgs WG Meeting 10/21/05
MCFM
NLO
LO
12
QCD NLO Corrections to H+1j
K-factors remain strong after jet veto
NLO
LO
After jet veto
PT2>30 GeV (parton
level) and |пЃЁ|<2
Bruce Mellado, Higgs WG Meeting 10/21/05
NLO
LO
After jet veto
PT2>30 GeV (parton
level) and |пЃЁ|<2
13
QCD NLO Corrections to H+1j
Leading jet’s PT before and after veto
NLO
LO
Before jet veto
Bruce Mellado, Higgs WG Meeting 10/21/05
NLO
LO
After jet veto
PT2>30 GeV (parton
level) and |пЃЁ|<2
14
QCD NLO Corrections to H+1j
Higgs pseudorapidity before and after veto
NLO
LO
Before jet veto
Bruce Mellado, Higgs WG Meeting 10/21/05
NLO
LO
After jet veto
PT2>30 GeV (parton
level) and |пЃЁ|<2
15
QCD NLO Corrections to VBF H
NLO
LO
K пЂЅ 1.012 пЂ« 10
Bruce Mellado, Higgs WG Meeting 10/21/05
-4
M
HJ
16
Outlook and Conclusions
Low mass Higgs searches with Hп‚®пЃґпЃґ in association
with high PT jets are crucial at the LHC
We are investigating QCD Higher order corrections
to signal and background for пЃґпЃґ + 1jet
QCD HO corrections are large in the region of the
phase space where the signal-to-background is
optimal for searches
пѓ� QCD Z+1j is enhanced by a factor of 2
пѓ� Signal, H+1j is enhanced by a factor 1.75
пѓ� Need to re-optimize the analysis
пѓ� Signal significance does not decrease
Bruce Mellado, Higgs WG Meeting 10/21/05
17
Документ
Категория
Презентации
Просмотров
4
Размер файла
1 842 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа