Flavor Violating Higgs Decays Joachim Kopp Galileo Galilei - - PowerPoint PPT Presentation
Flavor Violating Higgs Decays Joachim Kopp Galileo Galilei Institute November 26, 2012 Based on work done in collaboration with Roni Harnik and Jure Zupan arXiv:1209.1397 Joachim Kopp Flavor Violating Higgs Decays 1 Outline Flavor mixing
Joachim Kopp Galileo Galilei Institute November 26, 2012
Based on work done in collaboration with Roni Harnik and Jure Zupan arXiv:1209.1397
Joachim Kopp Flavor Violating Higgs Decays 1
1
Flavor mixing in the Higgs sector
2
Couplings to leptons
3
Couplings to quarks
4
Flavor-violating Higgs decays at the LHC
5
Summary
Joachim Kopp Flavor Violating Higgs Decays 2
Scenario 1: Several sources of EW symmetry breaking
If fermion masses have more than one origin, they do not need to be aligned with the Yukawa couplings Simplest example: Type III 2-Higgs-Doublet Model LY ⊃ −Y (1)
ij
¯ Liej
RH(1) − Y (2) ij
¯ Liej
RH(2) + h.c.
− → −mi¯ ei
Lei R − Y eff ij ¯
f i
Lf j Rh + couplings to heavier Higgs bosons + h.c.
(h = Lightest neutral Higgs boson, mh ∼ 125 GeV)
Assume heavy Higgs boson are decoupled.
see for instance Davidson Greiner, arXiv:1001.0434
Joachim Kopp Flavor Violating Higgs Decays 4
Scenario 2: Extra Higgs couplings
Assume existence of heavy new particles, which induce effective operators of the form ∆LY = − λ′
ij
Λ2 (¯ f i
Lf j R)H(H†H) + h.c. + · · · ,
→ after EWSB, new (but misaligned) contributions to mass matrices and Yukawa couplings Effective Lagrangian is again LY ⊃ −mi¯ ei
Lei R − Y eff ij ¯
f i
Lf j Rh + h.c.
see for instance Giudice Lebedev, arXiv:0804.1753
Joachim Kopp Flavor Violating Higgs Decays 5
Effective Yukawa Lagrangian
LY = −mi¯ f i
Lf i R − Y a ij (¯
f i
Lf j R)ha + h.c. + · · ·
Previously studied by many authors: Bjorken Weinberg, PRL 38 (1977) 622 McWilliams Li, Nucl. Phys. B 179 (1981) 62 Shanker, Nucl. Phys. B 206 (1982) 253 Barr Zee, PRL 65 (1990) 21 Babu Nandi, hep-ph/9907213 Diaz-Cruz Toscano, hep-ph/9910233 Han Marfatia, hep-ph/0008141 Kanemura Ota Tsumura, hep-ph/0505191 Blanke Buras Duling Gori Weiler, arXiv:0809.1073 Casagrande Goertz Haisch Neubert Pfoh, arXiv:0807.4937 Giudice Lebedev, arXiv:0804.1753 Aguilar-Saavedra, arXiv:0904.2387 Albrecht Blanke Buras Duling Gemmler, arXiv:0903.2415 Buras Duling Gori, arXiv:0905.2318 Azatov Toharia Zhu, arXiv:0906.1990 Agashe Contino, arXiv:0906.1542 Davidson Greiner, arXiv:1001.0434 Goudelis Lebedev Park, arXiv:1111.1715 Blankenburg Ellis Isidori, arXiv:1202.5704 Arhrib Cheng Kong, arXiv:1208.4669 McKeen Pospelov Ritz, arXiv:1208.4597 . . .
Joachim Kopp Flavor Violating Higgs Decays 6
Effective Yukawa Lagrangian
LY = −mi¯ f i
Lf i R − Y a ij (¯
f i
Lf j R)ha + h.c. + · · ·
New in this talk: Comprehensive list of up-to-date constraints (including subdominant ones) Omit approximations where feasible First LHC limits Strategy for future LHC searches
Joachim Kopp Flavor Violating Higgs Decays 6
h µ+ e− e+ µ−
Y ∗
eµPL + YµePR
Y ∗
eµPL + YµePR
M– ¯ M oscillations
h N µ N e
Y ∗
µePL + YeµPR
µ–e conversion
τ h τ µ γ µ
Y ∗
µτPL + YτµPR
Y ∗
τµPL + YµτPR
g − 2, EDMs
h τ µ µ µ
Y ∗
τµPL + YµτPR
Y ∗
µµPL + YµµPR
τ → 3µ, µee, etc.
τ h τ τ γ µ
Y ∗
ττPL + YττPR
Y ∗
τµPL + YµτPR
µ h γ, Z t t τ γ µ µ h γ, Z W W τ γ µ µ h γ, Z W W τ γ µ
τ → µγ, µ → eγ, etc.
Joachim Kopp Flavor Violating Higgs Decays 8
107 106 105104 103102 101 100 101 107 106 105 104 103 102 101 100 101 YeΜ Y Μe Μ eΓ M M Μ 3e Μ e conv.
D M
e
e f
I m
YeΜ
D Me f
R e
YeΜ
YeΜ
m Μ
BRh Μe 0.99 109 108 107 106 105 104 103 102 101 0.5 see also: Blankenburg Ellis Isidori, arXiv:1202.5704 Goudelis Lebedev Park, arXiv:1111.1715
Joachim Kopp Flavor Violating Higgs Decays 9
Assumption here: Diagonal Yukawa coupling unchanged from their SM values.
10 3 10 2 101 100 10 3 10 2 101 100 YΜΤ YΤΜ Τ ΜΓ Τ 3 Μ
D M
Μ
m
Τ Μ
Y
Μ Τ
Τ Μ
Y
Μ Τ
Μ
m
Τ
2
BR h ΤΜ 0.99 10 3 10 2 10 1 0.5 0.75
105 104 10 3 10 2 101 100 105 104 10 3 10 2 101 100 YeΤ YΤe Τ eΓ Τ eΜΜ
D M
e
f
I m
Τ e
Y
e Τ
Τ e
Y
e Τ
e
m
Τ
2
BR h Τe 0.99 10 6 10 5 10 3 10 2 10 1 0.5
E D M
e
e
Τ e
Y
e Τ
see also: Blankenburg Ellis Isidori, arXiv:1202.5704 Goudelis Lebedev Park, arXiv:1111.1715 Davidson Greiner, arXiv:1001.0434
Joachim Kopp Flavor Violating Higgs Decays 10
Assumption here: Diagonal Yukawa coupling unchanged from their SM values.
Tight constraints from neutral meson oscillations
h ¯ d b ¯ b d
Y ∗
bdPL + YdbPR
Y ∗
bdPL + YdbPR
t h h t ¯ u c ¯ c u
Y ∗
ctPL + YtcPR
Y ∗
tuPL + YutPR
Y ∗
ctPL + YtcPR
Y ∗
tuPL + YutPR
Joachim Kopp Flavor Violating Higgs Decays 12
Tight constraints from neutral meson oscillations Work in Effective Field Theory: Heff = Cdb
2 (¯
bRdL)2 + ˜ Cdb
2 (¯
bLdR)2 + Cdb
4 (¯
bLdR)(¯ bRdL) + . . . Wilson coefficients constrained in UTfit (Bona et al.), arXiv:0707.0636
see also Blankenburg Ellis Isidori, arXiv:1202.5704
Technique Coupling Constraint D0 oscillations |Yuc|2, |Ycu|2 < 5.0 × 10−9 |YucYcu| < 7.5 × 10−10 B0
d oscillations
|Ydb|2, |Ybd|2 < 2.3 × 10−8 |YdbYbd| < 3.3 × 10−9 B0
s oscillations
|Ysb|2, |Ybs|2 < 1.8 × 10−6 |YsbYbs| < 2.5 × 10−7 K 0 oscillations ℜ(Y 2
ds), ℜ(Y 2 sd)
[−5.9 . . . 5.6] × 10−10 ℑ(Y 2
ds), ℑ(Y 2 sd)
[−2.9 . . . 1.6] × 10−12 ℜ(Y ∗
dsYsd)
[−5.6 . . . 5.6] × 10−11 ℑ(Y ∗
dsYsd)
[−1.4 . . . 2.8] × 10−13
Joachim Kopp Flavor Violating Higgs Decays 12
102 101 100 101 102 101 100 101 Yqt q c, u Ytq q c, u
0.5 101 102 103 104 105 0.5 101 102 103 104
BRh t q BRt hq
single top bound on Yct, Y tc single top bound on Y ut, Y tu t hq lim it Craig et al.
Constraints from Single top production
t h t t g q
Y ∗
ttPL + YttPR
Y ∗
tqPL + YqtPR
CDF 0812.3400, DØ 1006.3575 ATLAS 1203.0529
t → hq
Craig et al. 1207.6794 based on CMS multilepton search 1204.5341
Not sensitive t → Zq
CMS 1208.0957
Joachim Kopp Flavor Violating Higgs Decays 13
Basic idea:
h → τℓ has the same final state as h → ττℓ
(but is enhanced by 1/BR(τ → ℓ))
Recast h → ττ search
here: ATLAS, arXiv:1206.5971
We consider only 2-lepton final states Use VBF cuts
(much lower BG than gg fusion)
see however Davidson Verdier, arXiv:1211.1248 based on ATLAS, arXiv:1206.5971
200 300 400 5 10 15 20 25 ΤΤ collinear mass m ΤΤ GeV Events 10 GeV ATLAS 4.7 fb1 ATLAS MC
5 H Τ Τ 5 H Τ Μ
Y ΜΤ
2 Y ΤΜ 2 1 2 m Τ v
Joachim Kopp Flavor Violating Higgs Decays 15
Most important cuts
2 forward jets (pT,j1 > 40 GeV,
pT,j2 > 25 GeV, |∆η| > 3.0, minv
j1,j2 > 350 GeV)
no hard jet activity in between no b tags 2 opposite sign leptons ℓ1, ℓ2 with pT,ℓ 10–20 GeV (depending on
flavors)
τ momentum fraction x carried by ℓ1, ℓ2 satisfies 0.1 < x1,2 < 1.0
(computed in collinear approximation)
30 GeV < mℓℓ < 75 (100) GeV
for same (opposite) flavor leptons
/ ET > 20 (40) GeV
for same (opposite) flavor leptons
based on ATLAS, arXiv:1206.5971
200 300 400 5 10 15 20 25 ΤΤ collinear mass m ΤΤ GeV Events 10 GeV ATLAS 4.7 fb1 ATLAS MC
5 H Τ Τ 5 H Τ Μ
Y ΜΤ
2 Y ΤΜ 2 1 2 m Τ v
Joachim Kopp Flavor Violating Higgs Decays 15
Problem: 4 neutrinos in final state Solution: Assume all τ decay products collinear
Ellis Hinchliffe Soldate van der Bij, NPB 1987
Per τ: 2 unknown (|pντ |, |pνℓ|) 2 constraints: / ET,x, / ET,y
Joachim Kopp Flavor Violating Higgs Decays 16
Technicalities
Use MadGraph 5, v1.4.6, Pythia 6.4, PGS Use only 120–160 GeV bin Derive one-sided 95% CL limit
based on ATLAS, arXiv:1206.5971
200 300 400 5 10 15 20 25 ΤΤ collinear mass m ΤΤ GeV Events 10 GeV ATLAS 4.7 fb1 ATLAS MC
5 H Τ Τ 5 H Τ Μ
Y ΜΤ
2 Y ΤΜ 2 1 2 m Τ v
Result
BR(h → τµ) < 0.13
τµ + Y 2 µτ < 0.011
BR(h → τe) < 0.13
τe + Y 2 eτ < 0.011
Joachim Kopp Flavor Violating Higgs Decays 17
10 3 10 2 101 100 10 3 10 2 101 100 YΜΤ YΤΜ Τ ΜΓ Τ 3 Μ
D M
Μ
m
Τ Μ
Y
Μ Τ
Τ Μ
Y
Μ Τ
Μ
m
Τ
2
BR h ΤΜ 0.99 10 3 10 2 10 1 0.5 0.75
105 104 10 3 10 2 101 100 105 104 10 3 10 2 101 100 YeΤ YΤe Τ eΓ Τ eΜΜ
D M
e
f
I m
Τ e
Y
e Τ
Τ e
Y
e Τ
e
m
Τ
2
BR h Τe 0.99 10 6 10 5 10 3 10 2 10 1 0.5
E D M
e
e
Τ e
Y
e Τ
Flavor Violating Higgs Decays 18
10 3 10 2 101 100 10 3 10 2 101 100 YΜΤ YΤΜ Τ ΜΓ Τ 3 Μ
D M
Μ
m
Τ Μ
Y
Μ Τ
Τ Μ
Y
Μ Τ
Μ
m
Τ
2
Our LHC limit
ATLAS 7 TeV , 4.7 fb 1
BR h ΤΜ 0.99 10 3 10 2 10 1 0.5 0.75
105 104 10 3 10 2 101 100 105 104 10 3 10 2 101 100 YeΤ YΤe Τ eΓ Τ eΜΜ
D M
e
f
I m
Τ e
Y
e Τ
Τ e
Y
e Τ
e
m
Τ
2
Our LHC limit
ATLAS 7 TeV , 4.7 fb 1
BR h Τe 0.99 10 6 10 5 10 3 10 2 10 1 0.5
E D M
e
e
Τ e
Y
e Τ
Flavor Violating Higgs Decays 18
10 3 10 2 101 100 10 3 10 2 101 100 YΜΤ YΤΜ Τ ΜΓ Τ 3 Μ
D M
Μ
m
Τ Μ
Y
Μ Τ
Τ Μ
Y
Μ Τ
Μ
m
Τ
2
Our LHC limit
ATLAS 7 TeV , 4.7 fb 1
BR h ΤΜ 0.99 10 3 10 2 10 1 0.5 0.75
105 104 10 3 10 2 101 100 105 104 10 3 10 2 101 100 YeΤ YΤe Τ eΓ Τ eΜΜ
D M
e
f
I m
Τ e
Y
e Τ
Τ e
Y
e Τ
e
m
Τ
2
Our LHC limit
ATLAS 7 TeV , 4.7 fb 1
BR h Τe 0.99 10 6 10 5 10 3 10 2 10 1 0.5
E D M
e
e
Τ e
Y
e Τ
Flavor Violating Higgs Decays 18
Possible improvements
Different invariant mass formula
(assuming 1 neutrino rather than 3)
◮ Avoids smearing of signal ◮ Shifts Z → ττ peak to
lower invariant mass
Consider hadronic τ’s
(especially for CMS)
Modified cuts
◮ CMS h → τhadτℓ search requires
mT(ℓ, / pT) < 40 GeV to suppress W + jets
◮ In h → τhadµ, neutrino and muon
typically not collinear → large mT(ℓ, / pT)
Joachim Kopp Flavor Violating Higgs Decays 19
Possible improvements
Different invariant mass formula
(assuming 1 neutrino rather than 3)
◮ Avoids smearing of signal ◮ Shifts Z → ττ peak to
lower invariant mass
Consider hadronic τ’s
(especially for CMS)
Modified cuts
◮ CMS h → τhadτℓ search requires
mT(ℓ, / pT) < 40 GeV to suppress W + jets
◮ In h → τhadµ, neutrino and muon
typically not collinear → large mT(ℓ, / pT)
50 100 150 200 2 4 6 8 10 12 Transverse m ass of the Μp T system GeV Events 10 GeV
5 fb 1, 7 TeV MGPythia Delphes BG rescaled to CMS-HIG-11-029 Wjets Zjets h Τhad ΤΜ h Τhad Μ
Y ΜΤ
2YΤΜ 21 2 m Τ v
QCD BG neglected Joachim Kopp Flavor Violating Higgs Decays 19
50 100 150 200 250 300 5 10 15 20 ΤΜ invariant m ass m ΤΜ GeV Events 10 GeV
5 fb 1, 7 TeV MGPythia Delphes BG rescaled to CMS-HIG-11-029 Wjets Zjets h Τhad ΤΜ h Τhad Μ
Y ΜΤ
2YΤΜ 21 2 m Τ v
QCD BG neglected
50 100 150 200 250 300 5 10 15 ΤΜ invariant m ass m ΤΜ GeV Events 10 GeV
5 fb 1, 7 TeV MGPythia Delphes BG rescaled to CMS-HIG-11-029 Wjets Zjets h Τhad ΤΜ h Τhad Μ
Y ΜΤ
2YΤΜ 21 2 m Τ v
QCD BG neglected
For Yµτ, Yτµ close to the current upper limits, spectacular signals possible.
Joachim Kopp Flavor Violating Higgs Decays 20
Davidson Verdier, arXiv:1211.1248
Observations
Computed pT,ν (using collinear approximation) is ≃ / ET Muon in h → τµ is much harder than in h → τℓτℓ.
T
E δ
2 4 6 8 10
Events / 0.2
10 1 10
2
10
+ jets
l → Z t t WW,WZ,ZZ single-t SM Higgs Signal
(GeV)
T
Muon p
20 40 60 80 100 120 140 160 180 200
Events / 2 GeV
10 1 10
2
10
+ jets
l → Z t t WW,WZ,ZZ single-t SM Higgs Signal
Joachim Kopp Flavor Violating Higgs Decays 21
Davidson Verdier, arXiv:1211.1248
Observations
Computed pT,ν (using collinear approximation) is ≃ / ET Muon in h → τµ is much harder than in h → τℓτℓ.
T
E δ
2 4 6 8 10
(GeV)
T
Muon p
20 40 60 80 100 120 140 160 180 200
10
10 1 T
E δ
2 4 6 8 10
(GeV)
T
Muon p
20 40 60 80 100 120 140 160 180 200
10
10
10
Background Signal
Joachim Kopp Flavor Violating Higgs Decays 21
Davidson Verdier, arXiv:1211.1248
Observations
Computed pT,ν (using collinear approximation) is ≃ / ET Muon in h → τµ is much harder than in h → τℓτℓ.
T
E δ
2 4 6 8 10
(GeV)
T
Muon p
20 40 60 80 100 120 140 160 180 200
10
10 1 T
E δ
2 4 6 8 10
(GeV)
T
Muon p
20 40 60 80 100 120 140 160 180 200
10
10
10
Background Signal
Projected sensitivity
Davidson Verdier, arXiv:1211.1248
BR(h → τµ), BR(h → τe) < 4.5 × 10−3
Joachim Kopp Flavor Violating Higgs Decays 21
Flavor-violating Higgs couplings arise in
◮ Models with several sources of electroweak symmetry breaking ◮ Models with heavy fields coupled to the Higgs
In the lepton sector:
◮ Constraints from ℓ1 → ℓ2 + γ, ℓ1 → ℓ2 + X, µ–e conversion in nuclei, g − 2,
EDMs, M– ¯ M oscillations
◮ Strong constraints in the µ–e sector ◮ Very weak constraints in the τ–e and τ–µ sectors
In the quark sector:
◮ Strong constraints on couplings to light quarks ◮ Very weak constraints on couplings to top quarks
At the LHC
◮ Constraints on anomalous top–Higgs couplings from single top production ◮ A recast ATLAS h → τℓτℓ search already provides strongest limits on
h → τµ and h → τe
◮ A dedicated search would be much more sensitive Joachim Kopp Flavor Violating Higgs Decays 22