NLO for Higgs signalshiggs/talks/heinrich.pdf · Gudrun Heinrich Max Planck Institute for Physics,...
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Gudrun Heinrich Max Planck Institute for Physics, Munich NLO for Higgs signals
Transcript of NLO for Higgs signalshiggs/talks/heinrich.pdf · Gudrun Heinrich Max Planck Institute for Physics,...
Gudrun HeinrichMax Planck Institute for Physics, Munich
NLO for Higgs signals
P.Meridiani, EPS 2017
P.Meridiani, EPS 2017
we need to be sure about the systematic uncertainties to see something like this
status of higher (fixed) order predictions involving H
gg ! H
VBF
WH /ZH
(see also Kirill’s talk)
ttH
H + jets
H + single top
HH
�tot
d� bonus
mt ! 1black: (HEFT)
N^3LO NNLO N^3LL threshold resum.NLO EW, mixed QCD/EW
N^3LO NNLO
NNLO NNLO NLO EW
NLO EW
NLO NLO NNLL threshold resum.
NLO NLO
NLO EW
1j: NNLO 1j: NNLO
NNLO NNLO NLO
H+1jet NLO: mb dependenceNLO up to 3jets
NLL resum.
NNLL resum.
blue: dependencemq
gg to ZH mt dep. approx.
status of higher (fixed) order predictions involving H
gg ! H
VBF
WH /ZH
ttH
H + jets
H + single top
HH
�tot
d� bonusN^3LO NNLO (+NNLL) N^3LL threshold resum.
NLO EW, mixed QCD/EW
N^3LO NNLO
NNLO NNLO NLO EW
NLO EW
NLO NLO
NNLL threshold resum.NLO NLO
NLO EW
1j: NNLO 1j: NNLO
NNLO NNLONLO
H+1jet NLO: mb dependence
NLO up to 3jets
Beenakker et al ’01; Dawson, Reina ’02; Frederix et al ‘14
Borowka, Greiner, GH, Jones, Kerner, Schlenk, Schubert, Zirke ‘16
Lindert, Melnikov, Tancredi, Wever ‘17
Frixione et al ’14; (on-shell)Denner, Lang, Pellen, Uccirati ’16
Kulesza et al ‘15
Anastasiou et al ’13-’15
Cullen et al ’13
Boughezal, Caola et al ’15; Boughezal et al ’15; Chen et al ’15; Dulat, Mistlberger ‘17
De Florian, Mazzitelli ’15; Steinhauser et al ‘15 De Florian et al ’16
Demartin, Maltoni, Mawatari, Zaro ’15
Brein, Djouadi, Harlander ’03;Brein, Harlander, Wiesemann, Zirke ’11
Ferrera, Grazzini, Tramontano ’11,’14
Denner, Dittmaier, Kallweit, Mück ‘12gg to ZH 1/mtAltenkamp et al ‘12
NLL resum. Ferrera, Pires ’16
NNLL threshold resum.
Ciccolini, Denner, Dittmaier ‘07Bolzoni, Maltoni, Moch, Zaro ’10;
Dreyer, Karlberg ‘16Cacciari, Dreyer, Karlberg,
Salam, Zanderighi ‘15
Dulat, Mistlberger ’17
Bizon, Monni, Re, Rottoli, Torrielli ‘17
Harlander et al ’14
De Florian, Grazzini, Tommasini ’11,‘12Degrassi, Maltoni ’04; Actis, Passarino, Sturm, Uccirati ’08; Anastasiou et al ‘08
status of parton shower matched results
gg ! H
VBF
ttH
H + jets
H + single top
HH
NNLO
NLO
NLO
NLO
NLO
WH /ZH
Frederix, Frixione, Vryonidou, Wiesemann ‘16
GH, Jones, Kerner, Luisoni, Vryonidou ’17; Jones, Kuttimalai ‘17
NLO up to 2jetsBuschmann, Goncalves, Krauss, Kuttimalai, Schönherr, Plehn ‘14
Frederix et al ’11; Garzelli et al ’11; Hartanto et al ’15; QCD and EW: Denner, Lang, Pellen, Uccirati ‘16
NLO (+ 0/1-jet merging) Luisoni, Nason, Oleari, Tramontano ’13
NLO QCD+EW Granata, Lindert, Oleari, Pozzorini ’17
Goncalves, Krauss, Kuttimalai, Maierhöfer ’15; Astill, Bizon, Re, Zanderighi’ 16
NNLO
Demartin, Maltoni, Mawatari, Zaro ’15
Hamilton, Nason, Re, Zanderighi ’13; Höche, Li, Prestel ’14;Alioli et al ’13,‘15
Nason, Oleari ’10; Frixione, Torrielli, Zaro ’13; Campanario et al ’13; Jäger et al ‘14
Higgs@NLO
some pressing problems to solve at NLO:
• quark mass effects “boosted Higgs can resolve loops from heavy BSM particles” and heavy SM particles (top)!
• EW corrections, combination QCD/EW
• multi-jet merging
• improve logarithmic accuracy of parton showers
• finding “optimal” scales/assessment of scale uncertainties
• consistent combination of EFT and SM NLO corrections
(also shower/resummation scale uncertainties)
Higgs pT
Forte, Muselli ’15;Marzani, Ball, del Duca, Forte, Vicini ’08; high-energy resummation of Higgs pT in gg ! H with off-shell gluons
d�/dp2T,h !�p2T,h
��1
for pT,h ! 1 :
d�/dp2T,h !�p2T,h
��2
Caola, Forte, Marzani, Muselli, Vita ’16
Caola, Forte, Marzani, Muselli, Vita ’16
quark mass effects in Higgs + jetsGreiner, Höche, Luisoni, Schönherr, Winter ’16
cross sections (+Ntuples) for H+1,2,3 jets calculated at
• NLO in HEFT ( mt ! 1 limit )• LO with full mt,mb dependence
default scale choice:
basic cuts:
quark mass effects in Higgs + jets
• different jet multiplicities show very similar behaviour
mt ! 1 limit starts to fail at pT,H ⇠ 200GeV
• leading jet pT distribution also similar
suggests that resolution of top quark loops is driven by pT,Hor largest pT in the event
jet multiplicity seems to play minor role
needs further investigation (backup slide)
Effect of VBF cuts
VBF cuts can enhance the deviations of HEFT to full theory
bottom quark effects
• well below the scale uncertainties even at low pT
• depend on jet multiplicity
• destructive interference between top- and bottom-quark loops for
H+1jet
Frederix, Frixione, Vryonidou, Wiesemann ‘16
Higgs+0,1,2 jets + parton shower
see also Buschmann, Goncalves, Krauss, Kuttimalai, Schönherr, Plehn ‘14
H + n jets:
• exact 2-loop virtual for n=0
• rescaled HEFT virtual for n=1,2
• exact mass dependence in real radiation
Higgs + jetLindert, Melnikov, Tancredi, Wever ‘17
Chris Wever, RadCor 2017
Higgs + jetLindert, Melnikov, Tancredi, Wever ‘17
• large relative corrections top-bottom interference to top-top
• large mb renormalisation ambiguities (light bands)reduced at NLO, in particular at low pT
Higgs + jet
Neumann, Williams ‘17• exact mass dependence
in real radiation
1/mt expansion • virtual part:
NLO*:
on amplitude level
fullasy: expansion on amplitude squared level
• method works well for scales up to about 300 GeV
towards Higgs + jet at full NLOJones, Kerner, Luisoni
Frederix, Frixione, Hirschi, Maltoni, Mattelaer, Torrielli, Vryonidou, Zaro ‘14
�ggHH ⇠ 10�3 �ggH
largest cross section from gluon fusion, but still
Higgs boson pair production
LO with full heavy quark mass dependence Glover, van der Bij ’88, Plehn, Spira, Zerwas ’96
Higgs boson pair production in gluon fusion
Note: limit: “Higgs Effective Field Theory” (HEFT)mt ! 1
HH production threshold: 2mH <ps
HEFT strictly valid only for ps ⌧ 2mt validity of HEFT limited to
250GeV <ps < 340GeV
)o
LO with full heavy quark mass dependence Glover, van der Bij ’88, Plehn, Spira, Zerwas ’96
Higgs boson pair production in gluon fusion
Note: limit: “Higgs Effective Field Theory” (HEFT)mt ! 1
HH production threshold: 2mH <ps
HEFT strictly valid only for ps ⌧ 2mt validity of HEFT limited to
250GeV <ps < 340GeV
)o
NLO in Born-improved HEFT Dawson, Dittmaier, Spira ’98 (HPAIR)
Frederix, Hirschi, Mattelaer, Maltoni, Torrielli, Vryonidou, Zaro ’14; Maltoni, Vryonidou, Zaro ’14
-10%• full mass dependence in NLO real radiation (“FTapprox”)
Grigo, Hoff, Melnikov, Steinhauser ’13, ’15 ; Degrassi, Giardino, Gröber ’16 (±10%)• supplemented with expansion: 1/mt
“Born-improved NLO HEFT”: rescale by MLO(mt)/MLOHEFT
K ' 2
• soft gluon resummation NNLL Shao, Li, Li, Wang ’13; De Florian, Mazzitelli ‘15
NNLO in mt ! 1 limit:
De Florian, Mazzitelli ’13
• including all matching coefficients Grigo, Melnikov, Steinhauser ’14
+20%
Grigo, Hoff, Steinhauser ’15 • supplemented with expansion: 1/mt
Higgs boson pair production in gluon fusion
• differential NNLO De Florian, Grazzini, Hanga, Kallweit, Lindert, Maierhöfer, Mazzitelli, Rathlev ‘16
• total xs NNLO
+9%
• soft gluon resummation NNLL Shao, Li, Li, Wang ’13; De Florian, Mazzitelli ‘15
NNLO in mt ! 1 limit:
De Florian, Mazzitelli ’13
• including all matching coefficients Grigo, Melnikov, Steinhauser ’14
+20%
Grigo, Hoff, Steinhauser ’15 • supplemented with expansion: 1/mt
Higgs boson pair production in gluon fusion
• differential NNLO De Florian, Grazzini, Hanga, Kallweit, Lindert, Maierhöfer, Mazzitelli, Rathlev ‘16
• total xs NNLO
+9%
NLO calculation with full top mass dependenceBorowka, Greiner, GH, Jones, Kerner, Schlenk, Schubert, Zirke ‘16
g
g
t
H
H
4 independent scales s12, s23, mH, mtall integrals calculated numerically with
SecDecBorowka, GH, Jones, Kerner, Schlenk, Zirke ‘15Borowka, GH, Jahn, Jones, Kerner, Schlenk, Zirke ‘17
Ferrera, Pires ‘16• resummation NLL+NLOqT
graphics by S.Jones
S.Borowka, GH, S.Jones, M.Kerner, J.Schlenk, T.Zirke ‘15
version 3.0:
algorithm:
http://secdec.hepforge.org
T. Binoth, GH ‘00version 1.0:version 2.0: S.Borowka, J. Carter, GH ‘12
J. Carter, GH ‘10
pySecDec: S.Borowka, GH, S.Jahn, S.Jones, M.Kerner, J.Schlenk, T.Zirke ‘17
numerical evaluation of multi-loop integrals https://github.com/mppmu/secdec/releases
S.Borowka, GH, S.Jones, M.Kerner, J.Schlenk, T.Zirke ‘15
version 3.0:
algorithm:
http://secdec.hepforge.org
T. Binoth, GH ‘00version 1.0:version 2.0: S.Borowka, J. Carter, GH ‘12
J. Carter, GH ‘10
pySecDec: S.Borowka, GH, S.Jahn, S.Jones, M.Kerner, J.Schlenk, T.Zirke ‘17
numerical evaluation of multi-loop integrals
can be used as an integral library
New!
https://github.com/mppmu/secdec/releases
• integrals calculated numerically with SecDec
• total number of integrals: g
g
t
H
H
calculation: building blocks
• amplitude reduction with Reduze [C. Studerus, A. v.Manteuffel]
• non-planar integrals computed mostly without reduction
• real radiation: (a) GoSam-1L + Catani-Seymour
dipole subtraction(b) GoSam-1L + POWHEG
• amplitude generation with 2 setups (custom made and “GoSam-2loop”)
• before reduction: ~10000, after reduction ~330, after sector decomposition 11244 (3086 non-planar)
• used finite basis for planar integrals
top mass effectstotal cross sections at 14 TeV
HXSWG:
• relative difference Born-improved NLO HEFT to full NLO:14 TeV: 16.4%
100 TeV: 31.5%27 TeV: 21.2%
scale uncertainties
top mass effects: energy dependence
preliminary, ± 0.3 stat. uncertainty
Higgs boson pair invariant mass
0
1
2
3
4
5
6
d�/d
mhh[fb/G
eV]
LO
B-i. NLO HEFT
NLO FTapprox
LO basic HEFT
NLO basic HEFT
NLO
300 400 500 600 700 800 900 1000mhh [GeV]
0.51.01.52.0
Kfa
ctor
0.00
0.05
0.10
0.15
0.20
d�/d
mhh[fb/G
eV]
LO
B-i. NLO HEFT
NLO FTapprox
LO basic HEFT
NLO basic HEFT
NLO
300 400 500 600 700 800 900 1000mhh [GeV]
0.51.01.52.0
Kfa
ctor
14 TeV 100 TeV
Born-improved NLO HEFT overestimates by about 50%, FTapprox by about 40% (at 14 TeV, worse at 100 TeV)
for large invariant masses:
top quark loops resolved HEFT has wrong scaling behaviour at high energies
rapidity of the Higgs boson pair
14 TeV 100 TeV
0.00
0.05
0.10
0.15
0.20
0.25
d�/d
mhh[fb/G
eV]
LO
NLO
NLO-i. NNLO HEFT
300 400 500 600 700 800 900 1000mhh [GeV]
0.51.01.52.0
Kfa
ctor
bin-by-bin rescaling at observable level by NNLO HEFT K-factor
d�NLO�i.NNLOHEFT
dmhh=
d�NLO
dmhh⇥ d�HEFT
NNLO/dmhh
d�HEFTNLO /dmhh
NLO-improved NNLO HEFTNNLO HEFT:
De Florian, Grazzini, Hanga, Kallweit, Lindert, Maierhöfer, Mazzitelli, Rathlev 1606.09519
“NLO-improved NNLO HEFT”: [Borowka, Greiner, GH, Jones, Kerner, Schlenk, Zirke 1608.04798]
�0 = 38.56 fb
would lead to
variation of triple Higgs coupling
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
d�/d
mhh[fb/G
eV]
LO
B-i. NLO HEFT
NLO FTapprox
LO basic HEFT
NLO basic HEFT
NLO
300 400 500 600 700 800 900 1000mhh [GeV]
0.51.01.52.0
Kfa
ctor
� = 0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
d�/d
mhh[fb/G
eV]
LO
B-i. NLO HEFT
NLO FTapprox
LO basic HEFT
NLO basic HEFT
NLO
300 400 500 600 700 800 900 1000mhh [GeV]
0.51.01.52.0
Kfa
ctor
� = �1
� = �BSM/�SM
�1 0 1 2 3 4 5
�
0
20
40
60
80
100
120
140
160
�[fb]
LO
NLO
NLO HEFT
NLO FTapprox
� = 2
cross section has a minimum around due to destructive interference
between diagrams containing �and box-type diagrams
0.0
0.2
0.4
0.6
0.8
1.0
1.2
d�/d
mhh[fb/G
eV]
LO
B-i. NLO HEFT
NLO FTapprox
LO basic HEFT
NLO basic HEFT
NLO
300 400 500 600 700 800 900 1000mhh [GeV]
0.51.01.52.0
Kfa
ctor
� = 5
degeneracy due to quadratic dependence�
distributions can discriminate between degenerate values�
variation of triple Higgs coupling
GH, S.Jones, M.Kerner, G.Luisoni, E.Vryonidou ‘17
• two-loop amplitude depends only on s, t (mt,mH fixed)
• variable transformation to achieve more uniform distribution
construct 2-dim grid
• avoid evaluation of two-loop amplitude for each phase space point
�(s) =q
1� 4m2H/s
combination with POWHEG and MadGraph5_aMC@NLO
and Sherpa
POWHEG-BOX-V2: User-Process-V2/ggHH
combination with parton showers
GH, S.Jones, M.Kerner, G.Luisoni, E.Vryonidou ‘17
• two-loop amplitude depends only on s, t (mt,mH fixed)
• variable transformation to achieve more uniform distribution
construct 2-dim grid
• avoid evaluation of two-loop amplitude for each phase space point
�(s) =q
1� 4m2H/s
combination with POWHEG and MadGraph5_aMC@NLO
and Sherpa New!
see Silvan Kuttimalai’s talk
POWHEG-BOX-V2: User-Process-V2/ggHH
combination with parton showers
grid validation
slide: S.Jones
hdamp = 1
hdamp=h limits amount of exponentiated hard radiation
dependence on shower parameters
hdamp = 1
hdamp=h limits amount of exponentiated hard radiation
dependence on shower parameters
shower effects large but order(s) of magnitude smaller than difference to Born-improved HEFT
• NLO is not “a solved problem”• finite mass effects are important
• in particular in tails of distributions, where they need to be distinguished from BSM effects
• combination of QCD corrections with NLO EW and EFT
pp ! HH, pp ! H + jet, gg ! HZ
means 2-loop integrals with many kinematic scales (too many for an analytic solution currently?) • HH@NLO done numerically (SecDec)
• NLO with full top mass dependence for
• increase precision by improvements on parton shower side (matching uncertainties, merging, log. acc.) and resummation
talk of Pier-Francesco Monni
talk of Alexander Mück many talks
lots of progress recently
summary & outlook
BACKUP SLIDES
compare POWHEG and MG5_aMC@NLO
MG5_aMC@NLO old shower starting scale Qsh:
MG5_aMC@NLO version 2.5.3:
picked with some probability distribution in old Qsh
new Qshnew Qshpicked with some probability distribution in
compare POWHEG and MG5_aMC@NLO
new default Qsh matches onto NLO fixed order at large pT
compare Pythia6 and Pythia8
ratio to lower jet multiplicity shows similar behaviour
quark mass effects in Higgs + jets
quark mass effects in Higgs + jetsGionata Luisoni, DIS 2017
10�1
100
X/
LO
H+
2
no veto applied
Ratio wrt. LO using mt ! 1 approximation.
0 100 200 300 400 500 600 700 800 900 1000
Higgs boson transverse momentum: pT, H [GeV]
10�1
100
X/
LO
H+
2(v
eto)
pT, H < 100 GeV
Ratio wrt. LO using mt ! 1 approximation.
10�8
10�7
10�6
10�5
10�4
10�3
10�2
10�1
100
101
d�/d
p T,H
[pb/G
eV]
GoSam + Sherpapp ! H + 3 jets at 13 TeV
CT14nlo, R = 0.4 anti-kT, |⌘jet| < 4.4, pT,jet = 100 GeV
LO H+3 (⇥10)
LO H+3 (veto)
LO H+3 mt,b (⇥10)
LO H+3 mt,b (veto)
LO H+3 mt (⇥10)
LO H+3 mt (veto)
quark mass effects in Higgs + jets
10�1
100
X/
LO
H+
2no veto applied
Ratio wrt. LO using mt ! 1 approximation.
100 200 300 400 500 600 700 800 900 1000Leading-jet transverse momentum: pT, j1 [GeV]
10�1
100
X/
LO
H+
2(v
eto)
pT, H < 100 GeV
Ratio wrt. LO using mt ! 1 approximation.
10�8
10�7
10�6
10�5
10�4
10�3
10�2
10�1
100
101
d�/d
p T,j
1[p
b/G
eV]
GoSam + Sherpapp ! H + 3 jets at 13 TeV
CT14nlo, R = 0.4 anti-kT, |⌘jet| < 4.4, pT,jet = 100 GeV
LO H+3 (⇥10)
LO H+3 (veto)
LO H+3 mt,b (⇥10)
LO H+3 mt,b (veto)
LO H+3 mt (⇥10)
LO H+3 mt (veto)
preliminary preliminary
Gionata Luisoni, DIS 2017
Higgs pT
Caola, Forte, Marzani, Muselli, Vita ’16
high-energy resummation of Higgs pT in gg ! H with off-shell gluons
Higgs + jet
Neumann, Williams ‘17
