Post on 02-Sep-2019
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
From Jet Scaling to Jet Vetos
Tilman Plehn
Heidelberg
ATLAS Higgs-Tau Workshop, 3/2012
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet counting
Why count jets
– complete event reconstruction crucial at LHC [Higgs plus 0,1,2 jets; jets plus /~pT ]
– utilize tagging and recoil jets in Higgs searches
– reduce t t and gg backgrounds
– identify decay jets in BSM searches
⇒ dσ/dnjets just another distribution to cut on?
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet counting
Why count jets
– complete event reconstruction crucial at LHC [Higgs plus 0,1,2 jets; jets plus /~pT ]
– utilize tagging and recoil jets in Higgs searches
– reduce t t and gg backgrounds
– identify decay jets in BSM searches
⇒ dσ/dnjets just another distribution to cut on?
Why not [intro: arXiv:0910.4182, Springer Lecture Notes]
– remember qg → qZ
– collinear divergence from g → qq splitting [overlapping with soft divergence]Z pmaxT
pminT
dp2T
Cp2
T
= 2Z pmax
T
pminT
dpT pTCp2
T
' 2CZ pmax
T
pminT
dpT1
pT= 2C log
pmaxT
pminT
universal form following factorization
σn+1 =
Zσn
dp2a
p2a
dzαs
2πP(z)
– universally divergent, fixed order poorly defined
⇒ find object to ‘renormalize’ [i.e. absorbe universal divergence]
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet counting
Why count jets
– complete event reconstruction crucial at LHC [Higgs plus 0,1,2 jets; jets plus /~pT ]
– utilize tagging and recoil jets in Higgs searches
– reduce t t and gg backgrounds
– identify decay jets in BSM searches
⇒ dσ/dnjets just another distribution to cut on?
DGLAP equation and jet-inclusive rates
– re-organize perturbation series [sum collinear logs]
σn+1(x, µ) ∼1n!
1
2πb0log
αs(µ20)
αs(µ2)
!n Z 1
x0
dxn
xnP„
xxn
«· · ·Z 1
x0
dx1
x1P„
x2
x1
«σ1(x1, µ0)
– DGLAP equivalent to ‘infrared RGE’
– factorization scale as inclusive momentum cutoff [vanishing at all orders]
σtot(µ) =
Z 1
0dx1
Z 1
0dx2
Xij
fi (x1, µ) fj (x2, µ) σij (x1x2S, µ)
⇒ collinear jets automatically included [veto on hard jets ok only if pmaxT ,j > hard scale]
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet counting
Why count jets
– complete event reconstruction crucial at LHC [Higgs plus 0,1,2 jets; jets plus /~pT ]
– utilize tagging and recoil jets in Higgs searches
– reduce t t and gg backgrounds
– identify decay jets in BSM searches
⇒ dσ/dnjets just another distribution to cut on?
DGLAP equation and jet-inclusive rates
– re-organize perturbation series [sum collinear logs]
σn+1(x, µ) ∼1n!
1
2πb0log
αs(µ20)
αs(µ2)
!n Z 1
x0
dxn
xnP„
xxn
«· · ·Z 1
x0
dx1
x1P„
x2
x1
«σ1(x1, µ0)
– DGLAP equivalent to ‘infrared RGE’
– factorization scale as inclusive momentum cutoff [vanishing at all orders]
σtot(µ) =
Z 1
0dx1
Z 1
0dx2
Xij
fi (x1, µ) fj (x2, µ) σij (x1x2S, µ)
⇒ collinear jets automatically included [veto on hard jets ok only if pmaxT ,j > hard scale]
⇒ but still...
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Poisson scaling
Theory: soft gluon radiation [Peskin & Schroeder Ch 6]
– example: photons off hard electrononly abelian diagrams, successive radiation
– eikonal approximation
Mn+1 = gsT aε∗µ(k) u(q)
qµ +O( /k)
(qk) +O(k2)Mn
– factorization of ‘hard process’ and soft radiation factors
– Poisson distribution [normalized pdf for n if n expected]
σn =nne−n
n!⇐⇒ R(n+1)/n =
σn+1
σn=
nn + 1
Basis of Poisson distribution
1– radiation matrix element nn:abelian fine, non-abelian a little tricky [ISR-FSR, see Ioffe, Fadin, Lipatov]
2– phase space factor 1/n!:only combinatorics, matrix element ordered [angular ordering, color suppression]
3– normalization factor e−n
– just like parton shower in collinear regimes
s
s
1/pT
1/pT
1/pT
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Staircase scaling
Experiment: from UA1 to ATLAS/CMS [Steve Ellis, Kleiss, Stirling]
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Staircase scaling
Experiment: from UA1 to ATLAS/CMS [Steve Ellis, Kleiss, Stirling]
– W/Z+jets production– many equivalent descriptions
R(n+1)/n =σn+1
σn= const
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Staircase scaling
Experiment: from UA1 to ATLAS/CMS [Steve Ellis, Kleiss, Stirling]
– W/Z+jets production– many equivalent descriptions
R(n+1)/n =σn+1
σn= const
– same for inclusive and exclusive rates [Blackhat-Sherpa]
R incl(n+1)/n =
P∞j=n+1 σ
(excl)j
σ(excl)n +
P∞j=n+1 σ
(excl)j
= Rexcl(n+1)/n
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Staircase scaling
Experiment: from UA1 to ATLAS/CMS [Steve Ellis, Kleiss, Stirling]
– W/Z+jets production– many equivalent descriptions
R(n+1)/n =σn+1
σn= const
– same for inclusive and exclusive rates [Blackhat-Sherpa]
R incl(n+1)/n =
P∞j=n+1 σ
(excl)j
σ(excl)n +
P∞j=n+1 σ
(excl)j
= Rexcl(n+1)/n
– confirmed by ATLAS/CMS
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Staircase scaling
Experiment: from UA1 to ATLAS/CMS [Steve Ellis, Kleiss, Stirling]
– W/Z+jets production– many equivalent descriptions
R(n+1)/n =σn+1
σn= const
– same for inclusive and exclusive rates [Blackhat-Sherpa]
R incl(n+1)/n =
P∞j=n+1 σ
(excl)j
σ(excl)n +
P∞j=n+1 σ
(excl)j
= Rexcl(n+1)/n
– confirmed by ATLAS/CMS
Theoretical studies [Englert, TP, Schichtel, Schumann]
– CKKW/MLM merging [we used Sherpa]
– phase space effects? → moderate
– αs uncertainties? → small
– scale uncertainties? → tuning parameter?jetsn
2 3 4 5 6
jets
dndN
210
310
410
510
610
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
jetsn2 3 4 5 6
jets
dndN
210
310
410
510
610
jetsn2 3 4 5 6
var
iati
onsα
0.5
1
1.5 theoretical uncertainty
statistical uncertainty
jetsn2 3 4 5 6
var
iati
onsα
0.5
1
1.5
jetsn2 3 4 5 6
var
iati
onµ
1
10
jetsn2 3 4 5 6
var
iati
onµ
1
10
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Staircase scaling
Experiment: from UA1 to ATLAS/CMS [Steve Ellis, Kleiss, Stirling]
– W/Z+jets production– many equivalent descriptions
R(n+1)/n =σn+1
σn= const
– same for inclusive and exclusive rates [Blackhat-Sherpa]
R incl(n+1)/n =
P∞j=n+1 σ
(excl)j
σ(excl)n +
P∞j=n+1 σ
(excl)j
= Rexcl(n+1)/n
– confirmed by ATLAS/CMS
Theoretical studies [Englert, TP, Schichtel, Schumann]
– CKKW/MLM merging [we used Sherpa]
– phase space effects? → moderate
– αs uncertainties? → small
– scale uncertainties? → tuning parameter?
– same for QCD jets
– correctly described by ME-PS merging!?
jetsn2 3 4 5 6
jets
dndN
410
510
610
710
810
910
1010
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
QCD
µQCD, 1/4
µQCD, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
QCD
µQCD, 1/4
µQCD, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
QCD
µQCD, 1/4
µQCD, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
QCD
µQCD, 1/4
µQCD, 4
jetsn2 3 4 5 6
jets
dndN
410
510
610
710
810
910
1010
jetsn2 3 4 5 6
var
iati
onsα 0.8
1
1.2 theoretical uncertainty
statistical uncertainty
jetsn2 3 4 5 6
var
iati
onsα 0.8
1
1.2
jetsn2 3 4 5 6
var
iati
onµ 1
10
210
jetsn2 3 4 5 6
var
iati
onµ 1
10
210
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Interpolating scaling patterns
Scaling for photon plus jets [Englert, TP, Schichtel, Schumann]
– naively, no scaling at all [CMS, private complaint]
– after appropriate cuts, great playground
1– staircasedemocratic γ and jet acceptancelarge γ-jet separation [m or ∆R, no large logs]
no reason for ordered emission [1/n! in Poisson form]
dominant: non-abelian splitting of ISR gluonhelping: pdf effect shifting to high-njets
2/1 3/2 4/3 5/4 6/5 7/6
nn+
1R
0
0.1
0.2
0.3
0.4
0.5
=-0.0064dndR
=0.15970R> 70 GeV, ,jγm
=-0.0007dndR
=0.14880R> 90 GeV, ,jγm
=0.0029dndR
=0.14070R>110 GeV, ,jγm
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Interpolating scaling patterns
Scaling for photon plus jets [Englert, TP, Schichtel, Schumann]
– naively, no scaling at all [CMS, private complaint]
– after appropriate cuts, great playground
1– staircasedemocratic γ and jet acceptancelarge γ-jet separation [m or ∆R, no large logs]
no reason for ordered emission [1/n! in Poisson form]
dominant: non-abelian splitting of ISR gluonhelping: pdf effect shifting to high-njets
2/1 3/2 4/3 5/4 6/5 7/6
nn+
1R
0
0.1
0.2
0.3
0.4
0.5
=-0.0064dndR
=0.15970R> 70 GeV, ,jγm
=-0.0007dndR
=0.14880R> 90 GeV, ,jγm
=0.0029dndR
=0.14070R>110 GeV, ,jγm
2– Poissongenerate ‘hard process’ [m, pT ,∆R, ...]
lower general pminT for soft-collinear logarithm
rely on lot-enhanced radiation
dominant: successive ordered ISRremaining: high-n staircase tail
⇒ staircase–Poisson transition tunable!
2/1 3/2 4/3 5/4 6/5 7/6 8/7n
n+1
R0
0.5
1
1.5 =1.7138n
=0.01310R>100 GeV,
T,j1p
=2.361n
=-0.05090R>150 GeV,
T,j1p
=2.6287n
=-0.05360R>200 GeV,
T,j1p
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Jet veto in Higgs analyses [Barger, Phillips, Zeppenfeld; Rainwater]
– particularly useful for WBF signals [remove t t and Z+jets backgrounds]
– veto central (semi-hard) jetsestimate Pvetoapply as ‘efficiency factor’
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Jet veto in Higgs analyses [Barger, Phillips, Zeppenfeld; Rainwater]
– particularly useful for WBF signals [remove t t and Z+jets backgrounds]
– veto central (semi-hard) jetsestimate Pvetoapply as ‘efficiency factor’
– implicit in LHC Higgs searchesindividual searches for exclusive fixed njets
– problem in Higgs phenomenology [mine for more than 10 years]
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Jet veto in Higgs analyses [Barger, Phillips, Zeppenfeld; Rainwater]
– particularly useful for WBF signals [remove t t and Z+jets backgrounds]
– veto central (semi-hard) jetsestimate Pvetoapply as ‘efficiency factor’
– implicit in LHC Higgs searchesindividual searches for exclusive fixed njets
– problem in Higgs phenomenology [mine for more than 10 years]
Using jet counting [Gerwick, TP, Schumann]
– avoid Pveto as single number
– study exclusive njets distribution:1– understand basic features:
staircase for inclusive samplesPoisson for radiation processes
2– predict from theory [including error]
3– validate simulation4– estimate alowed parameter range5– extrapolate to Higgs
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Jet veto in Higgs analyses [Barger, Phillips, Zeppenfeld; Rainwater]
– particularly useful for WBF signals [remove t t and Z+jets backgrounds]
– veto central (semi-hard) jetsestimate Pvetoapply as ‘efficiency factor’
– implicit in LHC Higgs searchesindividual searches for exclusive fixed njets
– problem in Higgs phenomenology [mine for more than 10 years]
Using jet counting [Gerwick, TP, Schumann]
– avoid Pveto as single number
– study exclusive njets distribution:1– understand basic features:
staircase for inclusive samplesPoisson for radiation processes
2– predict from theory [including error]
3– validate simulation4– estimate alowed parameter range5– extrapolate to Higgs
staircase scaling Poisson scaling
σn σ0 e−bn σtote−n nn
n!
Rexcl(n+1)/n e−b n
n + 1
Rincl(n+1)/n e−b
0@ (n + 1) e−n n−(n+1)
Γ(n + 1) − nΓ(n, n)+ 1
1A−1
〈njets〉1
2
1
cosh b − 1n
Pveto 1 − e−b e−n
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Example: WBF H → ττ [Gerwick, TP, Schumann]
– staircase scaling before WBF cuts [QCD and e-w processes]
– first emission sensitive to cuts
– e-w Zjj production with too many structures
1
n!/n+1!-1 0 1 2 3 4 5 6
) n!/
n+1
!R(
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Higgs gluon fusion
Z QCD
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
R(n
+1)
/n
n + 1
n
1/0 2/1 3/2 4/3 5/4 6/5
1
n!/n+1!-1 0 1 2 3 4 5 6
) n!/
n+1
!R(
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Higgs WBF
Z EW
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
R(n
+1)
/n
n + 1
n
1/0 2/1 3/2 4/3 5/4 6/5
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Example: WBF H → ττ [Gerwick, TP, Schumann]
– staircase scaling before WBF cuts [QCD and e-w processes]
– first emission sensitive to cuts
– e-w Zjj production with too many structures
Forward tagging jets
– count add’l veto jets to reduce backgrounds
pvetoT > 20 GeV min y1,2 < yveto
< max y1,2
– Poisson for QCD processes [‘radiation’ pattern]
1
n!/n+1!-1 0 1 2 3 4 5
) n!/
n+1
!R(
0
0.5
1
1.5
2
2.5
Higgs gluon fusion
Z QCD
n(Z QCD) = 1.42
n(Higgs gg fusion) = 1.80
0.5
1.0
1.5
2.0
2.5
R(n
+1)
/n
n + 1
n
1/0 2/1 3/2 4/3 5/4
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Example: WBF H → ττ [Gerwick, TP, Schumann]
– staircase scaling before WBF cuts [QCD and e-w processes]
– first emission sensitive to cuts
– e-w Zjj production with too many structures
Forward tagging jets
– count add’l veto jets to reduce backgrounds
pvetoT > 20 GeV min y1,2 < yveto
< max y1,2
– Poisson for QCD processes [‘radiation’ pattern]
– staircase-like for e-w processes [generic]
– features of njets distributions understood
⇒ cut on njets fine, your job now1
n!/n+1!-1 0 1 2 3 4 5
) n!/
n+1
!R(
0
0.5
1
1.5
2
2.5
Higgs gluon fusion
Z QCD
n(Z QCD) = 1.42
n(Higgs gg fusion) = 1.80
0.5
1.0
1.5
2.0
2.5
R(n
+1)
/n
n + 1
n
1/0 2/1 3/2 4/3 5/4
1
n!/n+1!-1 0 1 2 3 4 5
) n!/
n+1
!R(
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Higgs WBF
Z EW
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
R(n
+1)
/n
n + 1
n
1/0 2/1 3/2 4/3 5/4
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Higgs couplings
Veto probabilities crucial for coupling extraction [SFitter: Lafaye, TP, Rauch, Zerwas (2009ff)]
– theory:Higgs portal? [φ†φ gauge singlet]
γγH and ggH couplings w/o naive decouplingSUSY or strongly interacting Higgs simple coupling measurements
– experiment:Higgs decays to fermions crucialassociated Higgs-jet channels/WBF crucial
– current observables: σ × BRmore relevant: gjjH
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Higgs couplings
Veto probabilities crucial for coupling extraction [SFitter: Lafaye, TP, Rauch, Zerwas (2009ff)]
– theory:Higgs portal? [φ†φ gauge singlet]
γγH and ggH couplings w/o naive decouplingSUSY or strongly interacting Higgs simple coupling measurements
– experiment:Higgs decays to fermions crucialassociated Higgs-jet channels/WBF crucial
– current observables: σ × BRmore relevant: gjjH
Dedicated parameter analysis in progress [SFitter+Duhrssen, Klute]
– general fit of all couplings [Moriond 2012]
gjjH = gSMjjH`1 + ∆j
´– prelim: SM central values, proper errors
– pre-Moriond
0
0.5
1
1.5
2
110 115 120 125 130 135 140 145 150
mH [GeV]
68% CL ATLAS+CMS
∆W∆Z∆t∆b∆
τ∆H
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Higgs couplings
Veto probabilities crucial for coupling extraction [SFitter: Lafaye, TP, Rauch, Zerwas (2009ff)]
– theory:Higgs portal? [φ†φ gauge singlet]
γγH and ggH couplings w/o naive decouplingSUSY or strongly interacting Higgs simple coupling measurements
– experiment:Higgs decays to fermions crucialassociated Higgs-jet channels/WBF crucial
– current observables: σ × BRmore relevant: gjjH
Dedicated parameter analysis in progress [SFitter+Duhrssen, Klute]
– general fit of all couplings [Moriond 2012]
gjjH = gSMjjH`1 + ∆j
´– prelim: SM central values, proper errors
– pre-Moriondend of 2012
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
110 115 120 125 130 135 140 145 150
mH [GeV]
68% CL ATLAS+CMS
∆W∆Z∆t∆b∆
τ∆H
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Higgs couplings
Veto probabilities crucial for coupling extraction [SFitter: Lafaye, TP, Rauch, Zerwas (2009ff)]
– theory:Higgs portal? [φ†φ gauge singlet]
γγH and ggH couplings w/o naive decouplingSUSY or strongly interacting Higgs simple coupling measurements
– experiment:Higgs decays to fermions crucialassociated Higgs-jet channels/WBF crucial
– current observables: σ × BRmore relevant: gjjH
Dedicated parameter analysis in progress [SFitter+Duhrssen, Klute]
– general fit of all couplings [Moriond 2012]
gjjH = gSMjjH`1 + ∆j
´– prelim: SM central values, proper errors
– pre-Moriondend of 2012assuming mH = 125 GeV
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
∆H
∆W
∆Z
∆t
∆b
∆τ
∆γ
∆g
∆Z/W
∆τ/b
∆b/W
gj = gjSM
(1+∆j)
68% CL: ATLAS + CMS
7 TeV, 20 fb-1
14 TeV, 30 fb-1
no D5
14 TeV, 30 fb-1
with D5
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Higgs couplings
Veto probabilities crucial for coupling extraction [SFitter: Lafaye, TP, Rauch, Zerwas (2009ff)]
– theory:Higgs portal? [φ†φ gauge singlet]
γγH and ggH couplings w/o naive decouplingSUSY or strongly interacting Higgs simple coupling measurements
– experiment:Higgs decays to fermions crucialassociated Higgs-jet channels/WBF crucial
– current observables: σ × BRmore relevant: gjjH
Dedicated parameter analysis in progress [SFitter+Duhrssen, Klute]
– general fit of all couplings [Moriond 2012]
gjjH = gSMjjH`1 + ∆j
´– prelim: SM central values, proper errors
– pre-Moriondend of 2012assuming mH = 125 GeV
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
∆H
∆W
∆Z
∆t
∆b
∆τ
∆γ
∆g
∆Z/W
∆τ/b
∆b/W
gj = gjSM
(1+∆j)
68% CL: ATLAS + CMS
7 TeV, 20 fb-1
14 TeV, 30 fb-1
no D5
14 TeV, 30 fb-1
with D5
⇒ LHC task for coming years
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
New physics
Effective mass [Englert, TP, Schichtel, Schumann]
– obviously sensitive to new physics massesbut awful variable, after theory uncertainty
– correlation meff ∼ 〈pT 〉 × njets
– use merged sample for meffestimate scale and αs uncertainties
[GeV]effm200 400 600 800
[1/
100
GeV
]ef
fdmdN 310
410
510
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
[GeV]effm200 400 600 800
[1/
100
GeV
]ef
fdmdN 310
410
510
[GeV]effm200 400 600 800
var
iati
onsα 0.9
1
1.1 theoretical uncertainty
statistical uncertainty
[GeV]effm200 400 600 800
var
iati
onsα 0.9
1
1.1
[GeV]effm200 400 600 800
var
iati
onµ
1
10
[GeV]effm200 400 600 800
var
iati
onµ
1
10
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
New physics
Effective mass [Englert, TP, Schichtel, Schumann]
– obviously sensitive to new physics massesbut awful variable, after theory uncertainty
– correlation meff ∼ 〈pT 〉 × njets
– use merged sample for meffestimate scale and αs uncertainties
– estimate SUSY significance as function of meff
[GeV]effm200 400 600 800 1000 1200 1400
[1/
100
GeV
]ef
fdmdN
-210
-1101
10
210
310
410
510 signalleptonictt
hadronicttW+jetsZ+jetsQCD
[GeV]effm200 400 600 800 1000 1200 1400
[1/
100
GeV
]ef
fdmdN
-210
-1101
10
210
310
410
510
[GeV]effm200 400 600 800 1000 1200 1400
BS+
B
0.5
1
1.5
2
2.5
3
= 2jn
-1L = 1 fb
[GeV]effm200 400 600 800 1000 1200 1400
BS+
B
0.5
1
1.5
2
2.5
3 [GeV]effm200 400 600 800 1000 1200 1400
[1/
100
GeV
]ef
fdmdN
-210
-1101
10
210
310
410
510 signalleptonictt
hadronicttW+jetsZ+jetsQCD
[GeV]effm200 400 600 800 1000 1200 1400
[1/
100
GeV
]ef
fdmdN
-210
-1101
10
210
310
410
510
[GeV]effm200 400 600 800 1000 1200 1400
BS+
B
0.5
1
1.5
2
2.5
3
= 3jn
-1L = 1 fb
[GeV]effm200 400 600 800 1000 1200 1400
BS+
B
0.5
1
1.5
2
2.5
3
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
New physics
Effective mass [Englert, TP, Schichtel, Schumann]
– obviously sensitive to new physics massesbut awful variable, after theory uncertainty
– correlation meff ∼ 〈pT 〉 × njets
– use merged sample for meffestimate scale and αs uncertainties
– estimate SUSY significance as function of meff
– multijet studies establishing meff
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
New physics
Effective mass [Englert, TP, Schichtel, Schumann]
– obviously sensitive to new physics massesbut awful variable, after theory uncertainty
– correlation meff ∼ 〈pT 〉 × njets
– use merged sample for meffestimate scale and αs uncertainties
– estimate SUSY significance as function of meff
– multijet studies establishing meff
Mass vs color charge
– now, significance as function of njets
– representing new physics color charge [gluino does not decay via gluon]
– exclusive 2D likelihood including all information
2 3 4 5 6nj0.2
0.4
0.6
0.8
1.
1.2
1.4
1.6meffHTeVL
SPS1a, 1 inverse fb
0Σ
6Σ
2 3 4 5 6nj0.2
0.4
0.6
0.8
1.
1.2
1.4
1.6meffHTeVL
SPS1a, squarks+squarks, 1 inv. fb
0Σ
4Σ
2 3 4 5 6nj0.2
0.4
0.6
0.8
1.
1.2
1.4
1.6meffHTeVL
SPS1a, squarks+gluino, 1 inv. fb
0Σ
3.2Σ
2 3 4 5 6nj0.2
0.4
0.6
0.8
1.
1.2
1.4
1.6meffHTeVL
SPS1a, gluino+gluino, 1 inv. fb
0Σ
0.6Σ
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Exclusive jet counting
staircase (non-abelian) vs Poisson (ordered)
– start by measuring dσ/dnjets
– test both regimes in photon+jets
– test ME-PS merging [CKKW/MLM, unchanged by NLO]
– key to jet vetos
– key to coupling measurements [SFitter+friends]
Understanding Jet Scaling and Jet Vetos in Higgs SearchesE Gerwick, TP, S SchumannPRL 108 (2012)
Establishing Jet Scaling Patterns with a PhotonC Englert, TP, P Schichtel, S SchumannarXiv:1108.5473, JHEP in print
Jets plus Missing Energy with an AutofocusC Englert, TP, P Schichtel, S SchumannPRD83 (2011)
Much of this work was funded by the BMBF Theorie-Verbund which is ideal for hard and relevant LHC work