SLIDE 1
Lepton Number Violation at the LHC Bhupal Dev Washington University - - PowerPoint PPT Presentation
Lepton Number Violation at the LHC Bhupal Dev Washington University - - PowerPoint PPT Presentation
Lepton Number Violation at the LHC Bhupal Dev Washington University in St. Louis International Workshop on Baryon and Lepton Number Violation (BLV 2017) Case Western Reserve University, Cleveland May 17, 2017 Why Lepton Number Violation?
SLIDE 2
SLIDE 3
Seesaw Mechanism
A natural way to generate neutrino masses. Break the (B − L)-symmetry of the SM. Parametrized by the dim-5 operator (LLHH)/Λ. [Weinberg (PRL ’79)] Three tree-level realizations: Type I, II, III seesaw mechanisms.
YN
Y
eV
µ∆ YΣ eV eV
Generically predict lepton number and/or (charged) lepton flavor violation. Pertinent question in the LHC era: Can we probe the seesaw mechanism at the LHC (or future colliders)? Experimentally feasible if the seesaw scale is (in)directly accessible.
SLIDE 4
(Minimal) Type-I Seesaw at the LHC
SM-singlet heavy Majorana neutrinos. [Minkowski (PLB ’77); Mohapatra, Senjanovi´
c (PRL ’80); Yanagida ’79; Gell-Mann, Ramond, Slansky ’79; Glashow ’80]
Same-sign dilepton plus jets without / ET [Keung, Senjanovi´
c (PRL ’83); Datta, Guchait, Pilaftsis (PRD ’94); Han, Zhang (PRL ’06); del Aguila, Aguilar-Saavedra, Pittau (JHEP ’07); · · · ] q' q N W +
+ +
W q q V N V N ' (GeV)
N
m
50 100 150 200 250 300 350 400 450 500
2 N µ
V
- 5
10
- 4
10
- 3
10
- 2
10
- 1
10 1
Expected
s
CL σ 1 ± Expected
s
CL σ 2 ± Expected
s
CL Observed
s
CL L3 DELPHI CMS 7 TeV
(8 TeV)
- 1
19.7 fb
CMS [GeV]
N
m
100 150 200 250 300 350 400 450 500
2
|
N µ
|V
- 3
10
- 2
10
- 1
10 1 ATLAS
95% CL Observed limit 95% CL Expected limit σ 1 ± 95% CL Expected limit σ 2 ± 95% CL Expected limit
- 1
= 8 TeV, 20.3 fb s
[Talks by A. Salvucci and J. Kim]
SLIDE 5
Type-II Seesaw at the LHC
SU(2)L-triplet scalar (Φ++, Φ+, Φ0). [Schechter, Valle (PRD ’80); Magg, Wetterich (PLB ’80); Cheng, Li
(PRD ’80); Lazarides, Shafi, Wetterich (NPB ’81); Mohapatra, Senjanovi´ c (PRD ’81)]
Multi-lepton signatures. [Akeroyd, Aoki (PRD ’05); Fileviez Perez, Han, Huang, Li, Wang (PRD ’08); del Aguila,
Aguilar-Saavedra (NPB ’09); Melfo, Nemevsek, Nesti, Senjanovi´ c, Zhang (PRD ’12)]
Mass (GeV)
± ±
Φ
100 200 300 400 500 600 700 800 900 1000 Benchmark 4 Benchmark 3 Benchmark 2 Benchmark 1
±
τ
±
τ →
± ±
Φ 100%
±
τ
±
µ →
± ±
Φ 100%
±
τ
±
e →
± ±
Φ 100%
±
µ
±
µ →
± ±
Φ 100%
±
µ
±
e →
± ±
Φ 100%
±
e
±
e →
± ±
Φ 100%
Observed exclusion 95% CL Expected exclusion 95% CL Associated Production Pair Production Combined
(13 TeV)
- 1
12.9 fb
CMSPreliminary
[Talks by A. Salvucci and C. Mills]
SLIDE 6
Type-III Seesaw at the LHC
SU(2)L-triplet fermion (Σ+, Σ0, Σ−). [Foot, Lew, He, Joshi (ZPC ’89)] Multi-lepton signatures. [Franceschini, Hambye, Strumia (PRD ’08); Li, He (PRD ’09); Arhrib, Bajc, Ghosh, Han,
Huang, Puljak, Senjanovi´ c (PRD ’10); Ruiz (JHEP ’15)]
P1 P2 Z/γ∗/h Σ− Σ+ P1 P2 W ± Σ0 Σ±
Figure 1: Examples of Feynman diagrams for heavy fermion production in the type-III seesaw
Mass (GeV) Σ
400 500 600 700 800 900 1000
(pb) σ
3 −
10
2 −
10
1 −
10
- theo. unc.
σ ± ) Σ Σ → (pp σ 95% CL upper limits Observed Expected 1 std deviation 2 std deviation
CMS Preliminary (13 TeV)
- 1
35.9 fb
[Talk by A. Salvucci]
SLIDE 7
Outline
Low-scale seesaw (mostly focus on type-I) Lepton number violating and conserving signals (both are important) Beyond the minimal seesaw (gauge extensions) Complementarity with low-energy probes (LFV and 0νββ) Consequences for leptogenesis
SLIDE 8
Why low-scale seesaw?
In flavor basis {νc, N}, type-I seesaw mass matrix Mν =
- MD
MT
D
MN
- For ||MDM−1
N || ≪ 1, Mlight ν
≃ −MDM−1
N MT D .
In traditional GUT models, MN ∼ 1014 GeV. But in a bottom-up approach, allowed to be anywhere (down to eV-scale).
GUT
LEW
reactor & LSND anomaly mn
2=Dmatm 2
mn
2=Dmsol 2
eV keV GeV PeV ZeV MGUT MPl Ytop 10-3 Ye 10-7 10-9 10-11 Sterile neutrino mass scale Neutrino Yukawa coupling yn
SLIDE 9
Why low-scale seesaw?
In flavor basis {νc, N}, type-I seesaw mass matrix Mν =
- MD
MT
D
MN
- For ||MDM−1
N || ≪ 1, Mlight ν
≃ −MDM−1
N MT D .
In traditional GUT models, MN ∼ 1014 GeV. But in a bottom-up approach, allowed to be anywhere (down to eV-scale).
GUT
LEW
reactor & LSND anomaly mn
2=Dmatm 2
mn
2=Dmsol 2
eV keV GeV PeV ZeV MGUT MPl Ytop 10-3 Ye 10-7 10-9 10-11 Sterile neutrino mass scale Neutrino Yukawa coupling yn
Suggestive upper limit MN 107 GeV from naturalness arguments.
[Vissani (PRD ’98); Clarke, Foot, Volkas (PRD ’15); Bambhaniya, BD, Goswami, Khan, Rodejohann (PRD ’17)]
Allowed Region
mh 126 GeV NH mt 173.2 GeV Αs 0.1184
Naturalness ∆Μ2 1 TeV2 Naturalness ∆Μ2 5 TeV2 Naturalness ∆Μ2 0.2 TeV2 Metastability LFV Perturbativity
100 104 106 108 1010 1.0 10.0 5.0 2.0 20.0 3.0 1.5 15.0 7.0 MN GeV Im Z Allowed Region
mh 126 GeV IH mt 173.2 GeV Αs 0.1184
Naturalness ∆Μ2 1 TeV2 Naturalness ∆Μ2 5 TeV2 Naturalness ∆Μ2 0.2 TeV2 Metastability LFV Perturbativity
100 104 106 108 1010 1.0 10.0 5.0 2.0 20.0 3.0 1.5 15.0 7.0 MN GeV Im Z
SLIDE 10
Why low-scale seesaw?
In flavor basis {νc, N}, type-I seesaw mass matrix Mν =
- MD
MT
D
MN
- For ||MDM−1
N || ≪ 1, Mlight ν
≃ −MDM−1
N MT D .
In traditional GUT models, MN ∼ 1014 GeV. But in a bottom-up approach, allowed to be anywhere (down to eV-scale).
GUT
LEW
reactor & LSND anomaly mn
2=Dmatm 2
mn
2=Dmsol 2
eV keV GeV PeV ZeV MGUT MPl Ytop 10-3 Ye 10-7 10-9 10-11 Sterile neutrino mass scale Neutrino Yukawa coupling yn
Suggestive upper limit MN 107 GeV from naturalness arguments.
[Vissani (PRD ’98); Clarke, Foot, Volkas (PRD ’15); Bambhaniya, BD, Goswami, Khan, Rodejohann (PRD ’17)]
Allowed Region
mh 126 GeV NH mt 173.2 GeV Αs 0.1184
Naturalness ∆Μ2 1 TeV2 Naturalness ∆Μ2 5 TeV2 Naturalness ∆Μ2 0.2 TeV2 Metastability LFV Perturbativity
100 104 106 108 1010 1.0 10.0 5.0 2.0 20.0 3.0 1.5 15.0 7.0 MN GeV Im Z Allowed Region
mh 126 GeV IH mt 173.2 GeV Αs 0.1184
Naturalness ∆Μ2 1 TeV2 Naturalness ∆Μ2 5 TeV2 Naturalness ∆Μ2 0.2 TeV2 Metastability LFV Perturbativity
100 104 106 108 1010 1.0 10.0 5.0 2.0 20.0 3.0 1.5 15.0 7.0 MN GeV Im Z
Similar naturalness arguments in the context of neutral top partners [Batell, McCullough (PRD
’15)] and warped seesaw [Agashe, Hong, Vecchi (PRD ’16)] also predict a low seesaw scale.
SLIDE 11
Low-scale seesaw with large mixing
Naively, active-sterile neutrino mixing is small for low-scale seesaw: VlN ≃ MDM−1
N
≃
- Mν
MN 10−6
- 100 GeV
MN ‘Large’ mixing effects possible with special structures of MD and MN. [Pilaftsis (ZPC ’92);
Kersten, Smirnov (PRD ’07); Gavela, Hambye, Hernandez, Hernandez (JHEP ’09); Ibarra, Molinaro, Petcov (JHEP ’10); Deppisch, Pilaftsis (PRD ’11); Adhikari, Raychaudhuri (PRD ’11); Mitra, Senjanovi´ c, Vissani (NPB ’12)]
SLIDE 12
Low-scale seesaw with large mixing
Naively, active-sterile neutrino mixing is small for low-scale seesaw: VlN ≃ MDM−1
N
≃
- Mν
MN 10−6
- 100 GeV
MN ‘Large’ mixing effects possible with special structures of MD and MN. [Pilaftsis (ZPC ’92);
Kersten, Smirnov (PRD ’07); Gavela, Hambye, Hernandez, Hernandez (JHEP ’09); Ibarra, Molinaro, Petcov (JHEP ’10); Deppisch, Pilaftsis (PRD ’11); Adhikari, Raychaudhuri (PRD ’11); Mitra, Senjanovi´ c, Vissani (NPB ’12)]
One example: [Kersten, Smirnov (PRD ’07)] MD =
m1 δ1 ǫ1 m2 δ2 ǫ2 m3 δ3 ǫ3
and MN =
M1 M1 M2
with ǫi, δi ≪ mi. In the limit ǫi, δi → 0, all three light neutrino masses vanish at tree-level, while the mixing given by Vij ∼ mi/Mj can still be large. The textures can be stabilized by invoking discrete symmetries. [Kersten, Smirnov (PRD
’07); BD, Lee, Mohapatra (PRD ’13)]
But LNV is suppressed, as generically expected due to constraints from neutrino
- scillation data and 0νββ. [Abada, Biggio, Bonnet, Gavela, Hambye (JHEP ’07); Ibarra, Molinaro, Petcov
(JHEP ’10); Fernandez-Martinez, Hernandez-Garcia, Lopez-Pavon, Lucente (JHEP ’15)]
SLIDE 13
An Exception
For suitable choice of CP phases, resonant enhancement of the LNV amplitude for ∆mN ΓN. [Bray, Pilaftsis, Lee (NPB ’07)] ALNV ∝ V 2
ℓN
2∆mN ∆m2
N + Γ2 N
+ O
∆mN
mN
- Just like resonant enhancement of CP-asymmetry.
Ve1 = Vµ1 = Vµ2 = 0.05, Ve2 = 0.05i
SLIDE 14
A Natural Low-scale Seesaw
Inverse seesaw mechanism [Mohapatra (PRL ’86); Mohapatra, Valle (PRD ’86)] Two sets of SM-singlet fermions with opposite lepton numbers. Neutrino mass matrix in the flavor basis {νc, N, Sc}: Mν =
MD MT
D
MT
N
MN µ
≡
- MD
MT
D
MN
- Mlight
ν
= (MDM−1
N ) µ (MDM−1 N )T + O(µ3).
L-symmetry is restored when µ → 0.
SLIDE 15
A Natural Low-scale Seesaw
Inverse seesaw mechanism [Mohapatra (PRL ’86); Mohapatra, Valle (PRD ’86)] Two sets of SM-singlet fermions with opposite lepton numbers. Neutrino mass matrix in the flavor basis {νc, N, Sc}: Mν =
MD MT
D
MT
N
MN µ
≡
- MD
MT
D
MN
- Mlight
ν
= (MDM−1
N ) µ (MDM−1 N )T + O(µ3).
L-symmetry is restored when µ → 0. Naturally allows for large mixing: VlN ≃
- Mν
µ ≈ 10−2 1 keV µ as long as constraints
from EWPD [Akhmedov, Kartavtsev, Lindner, Michaels, Smirnov (JHEP ’13); de Blas ’13] are satisfied. Potentially large (LNC) signals at colliders. [del Aguila, Aguilar-Saavedra (PLB ’09); Chen, BD (PRD
’12); Das, BD, Okada (PLB ’14); Dev, Mohapatra (PRL ’15); Anamiati, Hirsch, Nardi (JHEP ’16)]
Important to also look for opposite-sign dilepton and trilepton signals.
q ¯ q′ W + l+ N l− W + l+ ν
SLIDE 16
New Contributions to Heavy Neutrino Production
Collinear-enhancement mechanism [BD, Pilaftsis, Yang (PRL ’14); Alva, Han, Ruiz (JHEP ’15); Degrande,
Mattelaer, Ruiz, Turner (PRD ’16); Das, Okada (PRD ’16)]
ection coherently
- f
LHC
[Talk by R. Ruiz (Pheno17)]
SLIDE 17
Higgs Decay
h N ¯ ν ν W + `− `+ h N ¯ ν `− Z ν `+
50 100 150 200 10-11 10-9 10-7 10-5 0.001 0.100 MN (GeV) |VeN
2
h<13 MeV h<1.1 SM h decay (14 TeV) (100 TeV) FCC-ee W d e c a y 50 100 150 200 10-11 10-9 10-7 10-5 0.001 0.100 MN (GeV) |VN
2
h<13 MeV h<1.1 SM h decay (14 TeV) (100 TeV) FCC-ee W decay 50 100 150 200 10-7 10-5 0.001 0.100 MN (GeV) |VeN
*VN|
h<13 MeV h<1.1 SM MEG 2 h decay (14 TeV) (100 TeV)
[BD, Franceschini, Mohapatra (PRD ’12); Cely, Ibarra, Molinaro, Petcov (PLB ’13); Das, BD, Kim (PRD ’17)]
Also potentially measurable effects in triple Higgs coupling [Baglio, Weiland (PRD ’16, JHEP ’17)]
SLIDE 18
Z Decay
ν ν ν ν N µ µ µ µ+ W- qq HNL mass (GeV)
1 10
2
|U|
- 11
10
- 10
10
- 9
10
- 8
10
- 7
10
- 6
10
Normal hierarchy BBN Seesaw BAU PS191 NuTeV SHiP FCC-ee
(a) Decay length 10-100 cm, 1012 Z0
Normal hierarchy HNL mass (GeV)
1 10
2
|U|
- 11
10
- 10
10
- 9
10
- 8
10
- 7
10
- 6
10
Inverted hierarchy BBN Seesaw BAU PS191 CHARM NuTeV SHiP FCC-ee
(a) Decay length 10-100 cm, 1012 Z0
Inverted hierarchy [Blondel, Graverini, Serra, Shaposhnikov ’14]
SLIDE 19
W Decay
W +
µ+ N µ+
e−
¯ νe
1 2 5 10 20 50 10-8 10-7 10-6 10-5 10-4 0.001 MN HGeVL »VmN 2
Trilepton search Lepton jet search SHiP proposal
[Izaguirre, Shuve (PRD ’15); Dib, Kim (PRD ’15); Dib, Kim, Wang, Zhang (PRD ’16)]
SLIDE 20
Displaced Vertex GeV
3 5 10 15 20 30 10 9 10 8 10 7 10 6 10 5 10 4
GeV
l4
DELPHI GeV GeV
GeV
3 5 10 15 20 30 109 108 107 106 105 104
mNGeV Vl4 2
DELPHI 0ΝΒΒ
3000 fb1 300 fb1 50 fb1
HL-LHC FCC-hh/SppC 20 40 60 80 100 10-11. 10-10. 10-9. 10-8. M [GeV] |
2
[Helo, Kovalenko, Hirsch (PRD ’14)] [Antusch, Cazzato, Fischer ’16]
SLIDE 21
Displaced Vertex in Higgs Decay
H Ni Nj l±
α
l±
β
q q q q [Caputo, Hernandez, Lopez-Pavon, Salvado ’17]
SLIDE 22
LNV in B-meson decays
W
+
+ u
- N
W b B
Neutrino mass [MeV]
1000 2000 3000 4000 5000
2
|
4
|V
- 5
10
- 4
10
- 3
10
- 2
10
- 1
10 1
μ
LHCb
[Aaij et al. (PRL ’14)]
SLIDE 23
LNV in B-meson decays
W
+
+ u
- N
W b B
1 2 3 4 5 10-4 0.001 0.010 0.100 mN (GeV) |V4
2 [Shuve, Peskin (PRD ’16)]
SLIDE 24
Summary Plot (Electron Sector) 0.5 5 50 500 10-11 10-9 10-7 10-5 0.001 0.100 MN (GeV) VeN
2
- DELPHI
L3
- FCC-ee
- K→eν
π→eν PS191 K→eeπ Belle
- NA3
- [Atre, Han, Pascoli, Zhang (JHEP ’09); Deppisch, BD, Pilaftsis (NJP ’15)]
SLIDE 25
Summary Plot (Muon Sector) 0.5 5 50 500 10-11 10-9 10-7 10-5 0.001 0.100 MN (GeV) VμN
2
- →μν
- DELPHI
L3
- FCC-ee
- EWPD
PS191
- NA3
K→μμπ
- [Atre, Han, Pascoli, Zhang (JHEP ’09); Deppisch, BD, Pilaftsis (NJP ’15)]
New limits from NA48/2 [Talk by M. Pepe]
SLIDE 26
Summary Plot (Tau Sector) 0.5 5 50 500 10-11 10-9 10-7 10-5 0.001 0.100 MN (GeV) VτN
2
- CHARM
NOMAD B-factory DELPHI
- FCC-ee
EWPD
- [Atre, Han, Pascoli, Zhang (JHEP ’09); Deppisch, BD, Pilaftsis (NJP ’15)]
SLIDE 27
U(1)B−L Extension
Z l
d
l
− β
u q q
N
d u
W
−
q q
N W
− '
0.2 0.4 0.6 0.8 1.0 1.2 1.4 10-10 10-8 10-6 10-4 10-2 mN @TeVD q
BrHmÆegL=5.7â10-13 10-16 10-20 10-24 10-28 LLHC=1 mm 100 mm 10 m
Dmsol
2
< q2mN < 0.3 eV
0.5 1.0 1.5 2.0 2.5 3.0 3.5 0.2 0.4 0.6 0.8 1.0 1.2 mZ' @TeVD mN @TeVD
1 fb 10 fb 102 fb 300fb-1 3000fb-1 Z'Æ2j Z'Æ{{
Displaced vertex signal (LNV/LFV)
[Fileviez Perez, Han, Li (PRD ’09); Deppisch, Desai, Valle (PRD ’14); Heeck, Teresi (PRD ’16)]
SLIDE 28
Probing Neutrino Mass Hierarchy at the LHC
0.0 0.5 1.0 1.5 2.0 10-6 0.001 1 1000
θR/π L (m) LHC displaced MATHUSLA NO
0.0 0.5 1.0 1.5 2.0 10-6 0.001 1 1000
θR/π L (m) LHC displaced MATHUSLA IO ee μμ eμ ττ
200 400 600 800 1000 1200 1400 1600 10-5 10-4 0.001 0.010 0.100
MN (GeV) σLNV (fb) NO ee μμ eμ ττ
200 400 600 800 1000 1200 1400 1600 10-5 10-4 0.001 0.010 0.100
MN (GeV) σLNV (fb) IO
[BD, Hagedorn, Molinaro (in prep.)]
SLIDE 29
Left-Right Seesaw
New contribution to Drell-Yan process via WR exchange. [Keung, Senjanovi´
c (PRL ’83); Ferrari et al (PRD ’00); Nemevsek, Nesti, Senjanovi´ c, Zhang (PRD ’11); Das, Deppisch, Kittel, Valle (PRD ’12); Lindner, Queiroz, Rodejohann, Yaguna (JHEP ’16); Mitra, Ruiz, Scott, Spannowsky (PRD ’16)] q ¯ q′ W +
R
ℓ+ N ℓ+ W −
R
j j
[TeV]
R
W
M
1 1.5 2 2.5 3
[TeV]
µ e, N
M
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4
R W
> M
µ e , N
M (8 TeV)
- 1
19.7 fb
CMS
Observed Expected
[GeV]
R
W
m 1000 1500 2000 2500 3000 3500 [GeV]
N
m 500 1000 1500 2000 2500 3000 ATLAS
µ µ ee +
- 1
= 8 TeV, 20.3 fb s
95% CL Observed limit 95% CL Expected limit σ 1 ± 95% CL Expected limit
R
W
=m
N
m
[Talks by A. Salvucci and J. Kim]
SLIDE 30
L-R Seesaw Phase Diagram
q ¯ q′ W + ℓ+ N ℓ+ W − j j q ¯ q′ W +
R
ℓ+ N ℓ+ W −
R
j j q ¯ q′ W +
R
ℓ+ N ℓ+ W − j j q ¯ q′ W + ℓ+ N ℓ+ W −
R
j j
(a) LL (b) RR (c) RL (d) LR
2 4 6 8 10 10-11 10-9 10-7 10-5 0.001 0.100 MWR (TeV) | VeN
2
LL RL RR EWPD
- MN = 1 TeV
2 3 4 5 6 1 2 3 4 mWR (TeV) mN (TeV) >
- | = -
- [Chen, BD, Mohapatra (PRD ’13); BD, Kim, Mohapatra (JHEP ’16)]
SLIDE 31
Displaced Vertex Signal
Mathusla[0.6] Mathusla[1.0] Mathusla[1.5] LHC [0.6] LHC [1.0] LHC [1.5]
0.5 1 5 10 50 2 5 10 20
mN [GeV] mWR [TeV]
s = 14 TeV 3000 fb-1
1 m 1 m 1 c m . 1 c m
Applicable for light RH neutrinos
[Castillo-Felisola, Dib, Helo, Kovalenko, Ortiz (PRD ’15); BD, Mohapatra, Zhang ’17]
SLIDE 32
Extended Higgs Sector
Under SU(3)c × SU(2)L × SU(2)R × U(1)B−L, Φ =
- φ0
1
φ+
2
φ−
1
φ0
2
- : (1, 2, 2, 0),
∆R =
- ∆+
R/
√ 2 ∆++
R
∆0
R
−∆+
R/
√ 2
- : (1, 1, 3, 2).
(See [Fileviez Perez, Murgui, Ohmer (PRD ’16)] for a simple alternative) 8 physical scalar fields, denoted by {h, H0
1, A0 1, H0 3, H± 1 , H±± 2
}. FCNC constraints require the bidoublet scalars (H0
1, A0 1, H± 1 ) to be 10 – 20 TeV. [An, Ji, Mohapatra, Zhang (NPB ’08); Bertolini, Maiezza, Nesti (PRD ’14)]
ℒ
∓ ∓ ∓
ℒ
SLIDE 33
Extended Higgs Sector
Under SU(3)c × SU(2)L × SU(2)R × U(1)B−L, Φ =
- φ0
1
φ+
2
φ−
1
φ0
2
- : (1, 2, 2, 0),
∆R =
- ∆+
R/
√ 2 ∆++
R
∆0
R
−∆+
R/
√ 2
- : (1, 1, 3, 2).
(See [Fileviez Perez, Murgui, Ohmer (PRD ’16)] for a simple alternative) 8 physical scalar fields, denoted by {h, H0
1, A0 1, H0 3, H± 1 , H±± 2
}. FCNC constraints require the bidoublet scalars (H0
1, A0 1, H± 1 ) to be 10 – 20 TeV. [An, Ji, Mohapatra, Zhang (NPB ’08); Bertolini, Maiezza, Nesti (PRD ’14)]
Doubly-charged scalars can give rise to distinct LNV signals at the LHC.
LHC8 excl. H2
++H2
- H2
±±jj (0.6)
H2
±±jj (1.0)
5 6 7 8 9 10 0.2 0.4 0.6 0.8 1.0
vR [TeV] MH2
±± [TeV]
s = 14 TeV, ℒ = 3 ab-1
LHC8 excl. H2
++H2
- H2
±±jj (0.6)
H2
±±jj (1.0)
H2
±±jj (1.5)
H2
±±WR ∓ (0.6)
H2
±±WR ∓ (1.0)
H2
±±WR ∓ (1.5)
5 10 15 20 25 30 35 0.2 0.5 1 2 5 10
vR [TeV] MH2
±± [TeV]
s = 100 TeV ℒ = 30 ab-1
[BD, Mohapatra, Zhang (JHEP ’16)]
SLIDE 34
Light Scalar as a New Probe of Seesaw
The CP-even neutral triplet component H0
3 can be light (GeV-scale).
Suppressed coupling to SM particles (either loop-level or small mixing). FCNC constraints necessarily require it to be long-lived. Unique displaced diphoton signal at the LHC.
0.01 0.05 0.10 0.50 1 5 10 10-14 10-11 10-8 10-5 10-2
mH3 [GeV] sin θ1
cosmological limits
K → πχχ B → Kχχ
K+ → π+νν NA62 B → Kν ν Belle II CHARM [K] DUNE [K] CHARM [B] SHiP [B] K mixing B
d
mixing Bs mixing LHC LLP searches MATHUSLA FCC LLP searches FCC forward detector [BD, Mohapatra, Zhang ’16; ’17]
SLIDE 35
Falsifying Leptogenesis
Any observation of LNV signal at the LHC will falsify high-scale leptogenesis.
[Deppisch, Harz, Hirsch (PRL ’14)]
f 1 f 2 qi q j
X Y Y
f 3 f 4
g1 g2 g4 g 3
'
X
f 1
Ψ
qi q j
Y
f 2 f 3 f 4
g1 g2 g 3 g4 1 2 3 4 5 108 106 104 102 100 102 MX TeV ΣLHC fb
WH1 102 102 104 106 108 1010
u u d d u d ΗL
EWΗL X10100
1010000 10106
In specific seesaw models, can also falsify low-scale leptogenesis. [Blanchet, Chacko,
Granor, Mohapatra (PRD ’10); Frere, Hambye, Vertongen (JHEP ’09); BD, Lee, Mohapatra ’15; Dhuria, Hati, Rangarajan, Sarkar (PRD ’15)]
1 0.1 MNMZ'2 1000 2000 3000 4000 5000 500 1000 1500 2000 2500 MZ' GeV MN GeV 1 0.1 2 1000 2000 3000 4000 5000 500 1000 1500 2000 2500 GeV GeV
- 1.0
- 0.5
0.0 0.5 1.0 5 10 15 20 25 30 Log10 [mN /TeV] mWR (TeV)
tot
Y =1
tot
Y =3
Weak Washout Strong Washout mN > mW R
SLIDE 36