recent smeft analysis at e+e- · recent smeft analysis at e+e-junping tian (u. of tokyo) ilc-jp...
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recent SMEFT analysis at e+e-
Junping Tian (U. of Tokyo)
ILC-JP Annual Physics &Detector Meeting, March 12-13, 2020
arXiv:1708.09079, 1708.08912; + papers in preparation
2
Global Fit: why do we need it?
suppose we discover a deviation in, e.g. cross section of e+e- -> ZH -> (μμ) (bb)
Z
ZHe+
e<
b
b̄
μ−
μ+
• hbb coupling? • hZZ coupling? • Zμμ coupling? • Zee coupling? • new diagrams?
then we would like to know which coupling is deviated:
3
From observables to couplings — Global Fit
�2 =n�
i=1
(Yi � Y �
i
�Yi)2
n: number of independent observables
Yi: measured values by experimentsYi’: predicted values by underlying theory
ΔYi: measurement uncertainty
kappa formalism
SM Effective Field Theory formalism
(Ai = Z,W, t)
(Bi = b, c, ⌧, µ, g, �, Z,W : decay)Y 0i= Fi ·
g2HAiAi
· g2HBiBi
�0
gHXX = �X ·gSMHXX
4
From observables to couplings — Global Fit
�2 =n�
i=1
(Yi � Y �
i
�Yi)2 + (Yj � Y �
j )T C�1j (Yj � Y �
j )
in case there are correlated observables
Yj: column vector of correlated observables
Cj: covariance matrix for those observables
one example: TGCs in SMEFT fit
5
BSM territory: can deviations be represented by single κZ?
Z
ZHe+
e<
Z
ZH
e +
e <
Z
ZH
e +
e < H Z
Z*∝ κ2
Z ∝?
σ(e+e− → Zh)SM
=Γ(h → ZZ*)
SM= κ2
Z ?
one question in kappa formalism:
6
�L = (1 + �Z)m2
Z
vhZµZµ + �Z
h
2vZµ�Zµ�
the answer is model dependent
Z
ZHe+
e<
�= Z
ZH
e +
e <
Z
ZH
e +
e < H Z
Z*
• BSM can induce new Lorentz structures in hZZ
• need a better, more theoretical sound framework
7
Le� = LSM + �L
= LSM +�
i
ci
�di�4Oi
• (background) kappa formalism not suitable for precision Higgs coupling determination @ future e+e-: model-dependent; radiative corrections
• SMEFT provides a more model independent formalism
• most general effects from BSM represented by higher dimensional ops.
• respect SU(3)xSU(2)xU(1) gauge symmetries
• consistently relate BSM effects in Higgs, W/Z, top, 2-fermion physics: provide a global view of roles of various measurements @ future e+e-
introduction: SM Effective Field Theory @ future e+e-
a global view of physics @ e+e-
8
Higgs
Top EW
BSM
9
global SMEFT fit @ e+e-
• 10 operators modifying couplings for h/Z/W/γ
(Barklow, Fujii, Jung, Peskin, JT, arXiv:1708.09079)
next: highlight a few important implications
Φ: higgs field W, B: SU(2), U(1) gauge L, e: left/right electron
• in total, 23 parameters (see later slides)
(“Warsaw” basis by Grzadkowski et al)
10
Z
ZH
e +
e <
Z
ZHe+
e<
Z
ZH
e +
e <
Z
ZHe+
e<
Z
Z He+
e<
Z
ZHe+
e<
e+e- ->Zhh e+e- ->Zh Z-pole
• Higgs coupling helped by EWPOs at Z-pole: ALR, Γl
• Z coupling helped by Higgs meas. at high √s: δσ ~ s/m2Z
recap 2: Higgs couplings are related to W-/Z- couplings (EWPOs)
+(c′ HL, cHE)
11
Z
Z He+
e<
Z
ZHe+
e<Z
Z
H
e+
e<
ISR
Z
new ideas: improving EWPOs @ ILC250
foreseen a factor of 10 better ALR keep exploring this new idea
a free gift by ISR: Higgs factory is meantime a Z factory
~108 Z events by ILC250, without any change of accelerator
more over, polarized beams
ILC250 = ILC250 + 100xLEP/SLC
radiative return
12
recap 4: role of beam polarizations
P(e-,e+)
(-1,+1)
(+1,-1)
gcos θw
(12
− sin2 θw)
gcos θw
(−sin2 θw)
g sin θw
g sin θw
gcos θw
(cHL + c′ HL)
gcos θw
(cHE)
• large cancellation in (+1,-1) -> weaker dependence on cWW
• ALR in σZH -> improve cWW, cHL+cHL’ and cHE
ζZ ζAZ
• sensitive to different couplings -> lift degeneracy
13
recap 4: role of beam polarizations (e+e- -> Zh)
δσL = − cH + 7.7(8cWW) + . . .
δσR = − cH + 0.6(8cWW) + . . .√s=250 GeV
δσ0 = − cH + 4.6(8cWW) + . . .
(8cWW) ~ 0.16% from other meas.
0.6
e−R
Bμcontribution from
almost cancels out
why?
up to a difference in Z/γ propagator suppressed by m2
Z
s
14
+ 4 SM parameters: g, g’, v, λ10 operators (h,W,Z,γ): cH, cT, c6, cWW, cWB, cBB, c3W, cHL, c’HL, cHE
+ 5 operators modifying h couplings to b, c, τ, μ, g
+ 2 parameters for h->invisible and exotic+ 2 operators for contact interactions with quarks
global SMEFT fit: full formalism (23 pars.)
15
+
Electroweak Precision Observables
Triple Gauge boson Couplings
Higgs observables at LHC & e+e-
+
strategy to determine all the 23 parameters at e+e-
(9)
(3)
(3+12x2)
2 for polarized
• at e+e-, all the 23 parameters can be determined simultaneously
(details in backup)
16
SMEFT: what’s next (an experimenter’s view)
16
SMEFT: what’s next (an experimenter’s view)
0degree of model dependence
SMEFT fit now 23 pars.
precision Higgs couplings; model discriminations;
global views; …
16
SMEFT: what’s next (an experimenter’s view)
reduction
0degree of model dependence
SMEFT fit now 23 pars.
precision Higgs couplings; model discriminations;
global views; …
16
SMEFT: what’s next (an experimenter’s view)
reductionBSM models
0degree of model dependence
SMEFT fit now 23 pars.
precision Higgs couplings; model discriminations;
global views; …
16
SMEFT: what’s next (an experimenter’s view)
reductionBSM models
matching; more symmetries;
weak / strong classifications; breaking of SMEFT;
…
0degree of model dependence
SMEFT fit now 23 pars.
precision Higgs couplings; model discriminations;
global views; …
16
SMEFT: what’s next (an experimenter’s view)
reductionBSM models
matching; more symmetries;
weak / strong classifications; breaking of SMEFT;
…
expansion
0degree of model dependence
SMEFT fit now 23 pars.
precision Higgs couplings; model discriminations;
global views; …
16
SMEFT: what’s next (an experimenter’s view)
reductionBSM models
matching; more symmetries;
weak / strong classifications; breaking of SMEFT;
…
expansion
including CP-odd ops.
0degree of model dependence
SMEFT fit now 23 pars.
precision Higgs couplings; model discriminations;
global views; …
16
SMEFT: what’s next (an experimenter’s view)
reductionBSM models
matching; more symmetries;
weak / strong classifications; breaking of SMEFT;
…
expansion
including CP-odd ops.
more fermion generations; all couplings
0degree of model dependence
SMEFT fit now 23 pars.
precision Higgs couplings; model discriminations;
global views; …
16
SMEFT: what’s next (an experimenter’s view)
reductionBSM models
matching; more symmetries;
weak / strong classifications; breaking of SMEFT;
…
expansionSMEFT @ NLO
including CP-odd ops.
more fermion generations; all couplings
0degree of model dependence
SMEFT fit now 23 pars.
precision Higgs couplings; model discriminations;
global views; …
(i) role of each measurement(e.g. Grojean et al, arXiv:1907.04311)
17Is there an easier way?
0 2 4 6 8]-1Integrated Luminosity [ab
0.5
1
1.5
2
2.5
3-1Pr
ecis
ion
Rel
ated
to 2
ab g(hZZ)
g(hbb)g(hcc)2/L
why not following 1/√L? why so different for hZZ/hbb/hcc?
role of each measurement: more transparent understanding(Fujii, Peskin, JT, paper in preparation)
18
role of each measurement: more transparent understanding
19
δghZZ =12
δσZh + 6.4δΓl + 5.3δgZ,eff − 0.015δRγZ − 2.4δκA,eff + 8.9δmh + 0.098δAl + ⋯
New idea: express analytically uncertainty of every EFT coefficient or Higgs coupling directly by a set of input observables
for example: unpolarized e+e- at 250 GeV
σΖh : cross section of e+e- -> Zh Al, Γl : ALR and Γ(Z->ll) at Z-pole gZeff, κΑeff : Triple Gauge Couplings RγZ : BR(h->γZ) / BR(h->ZZ*) mh : Higgs mass
δX =ΔXX
role of each measurement: more transparent understanding(Peskin, JT, paper in preparation)
20
δghZZ =12
δσZh + 6.4δΓl + 5.3δgZ,eff − 0.015δRγZ − 2.4δκA,eff + 8.9δmh + 0.098δAl + ⋯
plug in measurement precisions for current EWPOs + 2 ab-1
for example: unpolarized e+e- at 250 GeV
= 41 ⊕ 66 ⊕ 30 ⊕ 23 ⊕ 14 ⊕ 11 ⊕ 8.7 ⊕ ⋯ × 10−4
EWPOs
TGCsBR(h->γZ)
Higgs mass
σZh
importance hierarchy
21
(ii) what happens at next leading order for SMEFT
• at e+e-, NLO ~ O(α), 1% level• for NLO from W/Z/γ/H, operators constrained to ~<0.01,
overall effect will be < 0.1%
• for NLO from top, operators would be much less constrained, currently ~ O(1) -> overall effect 1% -> potential impact in global fit on Higgs coupling precision
Zhang, et al, arXiv:1804.09766, 1807.02121
Jung, Vos, JT, et al, work in progress
JT@LCWS18
22
our approach to include NLO top effects
• we didn’t try to include full NLO effects for all observables
• instead, include NLO effects that are log-enhanced
• captured by Renormalization Group Evolution (mixing)
·ci ≡ 16π2 dci
d ln μ= γijcj
• ci: Higgs operators; cj: Top operators
• in this way, we can consistently apply power-counting to all observables, e.g. EWPOs (major difference with earlier work)
Jung, Lee, Perello, Vos, JT, paper in preparation
23
typical loop diagrams with logarithmic dependence on top-operators
impact on Higgs couplings
impact on role of EWPOs
impact on synergy with LHC
24
results (I): √s = 250 GeV e+e-
• with the same set of observables, at 250 GeV running only, the global fit will not converge at any of the Higgs factories
• e.g. Higgs couplings could not be determined unambiguously
not surprising, but don’t worry
25
results (II): ILC250 + LHC
• LHC will provide us valuable top data sets, such as
• top operators will be constrained to some extent at (HL-)LHC
(Durieux, et al, arXiv:1907.10619)
pp → tt̄ + Z/W/γ t → Wb
26
results (II): ILC250 + LHC
• with the help of LHC top data, Higgs coupling precisions @ ILC250 are almost restored
• note: top data from LHC Run 2 is not constraining enough
1.75
%
1.99
%
1.81
%
1.75
%
1.28
%
1.62
%
1.89
%
9.79
%
3.64
% 4.16
%
��� ��� ��� ��� ��� ��� ��� ��� ��� ���� ������ ���� ��� ��
0.94
%1.03
%0.55
%0.55
%
1.73
%1.78
%1.1%
1.1%
1.08
%1.15
%0.71
%0.71
%
0.47
%0.64
%0.35
%0.35
%
0.48
%0.54
%0.35
%0.35
% 1.08
%1.11
%1.%
1.%
1.54
%1.59
%0.9%
0.9%
3.95
%3.96
%3.71
%3.71
%
9.05
%9.94
%6.38
%6.38
%
0.3%
0.3%
0.28
%0.28
%
1.51
%1.51
%1.15
%1.16
%
2.2% 2.35
%1.51
%1.51
%
3.27
%3.27
%
0.87
%1.26
%0.66
%0.66
%
w/ top + LHC Run 2w/ top + HL-LHC S2
w/o top w/ top (indirect only)+ HL-LHC S2+ ILC 500 (direct top)
w/o top
0
2
4
6
8
10
Errors[%
]
ILC 250 Stage ILC 500 Stage
12.7%
294%
27
summary
• the capabilities of a e+e- are best represented in SMEFT formalism
• EWPOs/TGCs/Top meas. are related to Higgs couplings
• Higgs/Top measurements from (HL-)LHC are helpful for e+e-
• beam polarizations play an important role
• all proposed Higgs factories can deliver 1% or below precision for many Higgs couplings already at √s = 250 GeV
28
backup
29
recap 1: absolute Higgs couplings (unique role of inclusive σZh)
renormalize kinetic term of SM Higgs field
h (1-cH/2)h
shift all SM Higgs couplings by -cH/2
cH
2�µh�µh
• cH can not be determined by any BR or ratio of couplings
• cH has to rely on inclusive cross section of e+e- -> Zh, enabled by recoil mass technique at e+e-
30
recap 2: Higgs couplings are related to W-/Z- couplings (TGCs)
• higgs coupling helped by meas. of TGCs in e+e- -> WW
• longitudinal modes of W/Z are from Higgs fields
Z
W+
W+W-
W-
A
W+ W-
!Z
W+
W+W-
W-
A
W+ W-
!Z
W+
W+W-
W-
A
W+ W-
!
+(cWW, cBB)
31
recap 3: Higgs couplings are related to themselves
• hZZ/hWW/hγZ/hγγ highly related: SU(2)xU(1) gauge symmetries
(SM structure: kappa like) (Anomalous: new Lorentz structure)
32
recap 3: Higgs couplings are related to themselves (synergy w/ LHC)
• loop induced h->γγ/γΖ depend strongly on cWW/cWB/cBB
two measurements from LHC (model independent)
+ …
+ …
+ …
• h->γγ/γZ at LHC can nicely help higgs couplings at e+e-
Rγγ =BR(h → γγ)
BR(h → ZZ*)RγZ =
BR(h → γZ)BR(h → ZZ*)
528
290
33
SM-like hVV
anomalous hVV
custodial symmetry is broken by cT -> constrained by EWPOs
ci ~ O(10-4-10-3)
• hWW/hZZ ratio can be determined to <0.1%
recap 3: Higgs couplings are related to themselves (hWW/hZZ)
• very important for physics case of any 250 GeV e+e- • hWW can be determined as precisely as hZZ at 250 GeV;
hence precision total width & other couplings
34
coupling ∆g/g kappa-fit EFT-fit
hZZ 0.38% 0.50%
hWW 1.8% 0.50%
hbb 1.8% 0.99%
Γh 3.9% 2.3%
(definition for higgs coupling precision: 1/2 of partial width precision)
ILC250: ∫Ldt = 2 ab-1 @ 250 GeV
SMEFT fit: typical difference with kappa fit
35
recap 4: role of beam polarizations (overall effects)
• 250 GeV e+e-: power of 2 ab-1 polarized ≈ 5 ab-1 unpolarized
ILC250: 2 ab-1 FCCee240: 5 ab-1
(arXiv:1903.01629)
0
0.5
1
1.5
2
2.5
3
3.5
Prec
isio
n of
Hig
gs b
oson
cou
plin
gs [%
]
Z W b τ g c invΓ hΓ γ γZ
1/3×
µ
1/2×
t
1/2×
λ
1/10×
ILC250⊕HL-LHC
ILC500⊕ ILC250 ⊕HL-LHC
dark/light: S1*/S2*
Model Independent EFT Fit LCC Physics WG
36
#qualitative:
precisions at Higgs factories: complementarity with LHC
model independence, hcc coupling
#quantitative (<~1%):hZZ, hWW, hbb, hττ h->invisible/exotic
#synergy:hγγ, hγΖ, hμμ, htt, λ
(arXiv:1903.01629)
37
new operators (to previous SMEFT fit)
38
effect of top operators: example
V V<latexit sha1_base64="(null)">(null)</latexit><latexit sha1_base64="(null)">(null)</latexit><latexit sha1_base64="(null)">(null)</latexit>
ctWv2
(Q̄�µ⌫t)⌧a�̃W aµ⌫
<latexit sha1_base64="(null)">(null)</latexit><latexit sha1_base64="(null)">(null)</latexit><latexit sha1_base64="(null)">(null)</latexit>
ctW<latexit sha1_base64="(null)">(null)</latexit><latexit sha1_base64="(null)">(null)</latexit><latexit sha1_base64="(null)">(null)</latexit>
t<latexit sha1_base64="(null)">(null)</latexit><latexit sha1_base64="(null)">(null)</latexit><latexit sha1_base64="(null)">(null)</latexit>
higgs operator top operator
log-enhanced
39
results
still preliminary; I will only show a few see more results in talk by S. Jung @ LCWS2019
paper on arXiv soon
40
results (III): polarized vs unpolarized
• polarization now shows its important role
• w/o beam polarizations, even with the help of HL-LHC top data, Higgs coupling precisions @ e+e-250 will suffer a lot
��� ��� ��� ��� ��� ��� ��� ��� ��� ���� ������ ���� ��� ����� ��� ��� ��� ��� ��� ��� ��� ��� ���� ������ ���� ��� ��
HL-LHC S2 + 2 /ab at 250 GeVw/o top
HL-LHC S2 + 5 /ab at 250 GeVw/o top
0.1
0.5
1
5
10
Errors[%
]
Polarized Unpolarized
41
results (IV): √s >= 350 GeV e+e-
• once e+e- -> t t-bar becomes accessible, effects of top operators on the Higgs coupling determination will be well under-control