[PPT] - Neutrino Models at Colliders Bhupal Dev Washington University in PowerPoint Presentation

SLIDE 1

Neutrino Models at Colliders

Bhupal Dev Washington University in St. Louis SUSY2019 Corpus Christi May 22, 2019

SLIDE 2

Harbinger of New Physics

Non-zero neutrino mass = ⇒ physics beyond the Standard Model

2

SLIDE 3

Harbinger of New Physics

Non-zero neutrino mass = ⇒ physics beyond the Standard Model

e µ τ u d c s b t TeV GeV MeV keV eV meV neutrinos

Perhaps something beyond the standard Higgs mechanism...

2

SLIDE 4

Harbinger of New Physics

Non-zero neutrino mass = ⇒ physics beyond the Standard Model

e µ τ u d c s b t TeV GeV MeV keV eV meV neutrinos

Perhaps something beyond the standard Higgs mechanism... Can we probe the origin of neutrino mass at colliders?

2

SLIDE 5

Neutrino Mass Models

[see Tuesday plenary talk by S. King]

From pheno point of view, can broadly categorize into

Tree-level (seesaw) vs loop-level (radiative) Minimal (SM gauge group) vs gauge-extended [e.g. U(1)B−L, Left-Right] Non-supersymmetric vs Supersymmetric

3

SLIDE 6

Neutrino Mass Models

[see Tuesday plenary talk by S. King]

From pheno point of view, can broadly categorize into

Tree-level (seesaw) vs loop-level (radiative) Minimal (SM gauge group) vs gauge-extended [e.g. U(1)B−L, Left-Right] Non-supersymmetric vs Supersymmetric

New fermions, gauge bosons, and/or scalars – messengers of neutrino mass physics. Rich phenomenology. For messenger scale O(few TeV), accessible at the LHC and/or future colliders. Connection to other puzzles (e.g. baryogenesis, dark matter).

3

SLIDE 7

New Fermions

(aka sterile neutrinos/heavy neutrinos/heavy neutral leptons)

4

SLIDE 8

Type-I Seesaw

[Minkowski (PLB ’77); Mohapatra, Senjanovi´ c (PRL ’80); Yanagida ’79; Gell-Mann, Ramond, Slansky ’79; Glashow ’80]

Introduce SM-singlet Majorana fermions (N). −L ⊃ YνLφcN + 1 2MNN

cN + H.c.

After EWSB, mν ≃ −MDM−1

N MT D, where MD = vYν. [Figure from Antusch, Cazzato, Fischer (IJMPA ’17)] 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 5

SLIDE 9

Type-I Seesaw

[Minkowski (PLB ’77); Mohapatra, Senjanovi´ c (PRL ’80); Yanagida ’79; Gell-Mann, Ramond, Slansky ’79; Glashow ’80]

Introduce SM-singlet Majorana fermions (N). −L ⊃ YνLφcN + 1 2MNN

cN + H.c.

After EWSB, mν ≃ −MDM−1

N MT D, where MD = vYν. [Figure from Antusch, Cazzato, Fischer (IJMPA ’17)] 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

Naturalness of Higgs mass suggests MN 107 GeV.

[Vissani (PRD ’98); Clarke, Foot, Volkas (PRD ’15); Bambhaniya, BD, Goswami, Khan, Rodejohann (PRD ’17)]

5

SLIDE 10

Heavy Majorana Neutrinos at the LHC

[Keung, Senjanovi´ c (PRL ’83); Datta, Guchait, Pilaftsis (PRD ’94); Panella, Cannoni, Carimalo, Srivastava (PRD ’02); Han, Zhang (PRL ’06); del Aguila, Aguilar-Saavedra, Pittau (JHEP ’07); Atre, Han, Pascoli, Zhang (JHEP ’09)]

Same-sign dilepton plus jets (without / ET)

q' q N W +

+ +

W q q V N V N '

(GeV)

N

m

2

10

3

10

Mixing

5 −

10

4 −

10

3 −

10

2 −

10

1 −

10 1

2 eN

V Observed

2 N µ

V Observed

2 N µ

V +

2 eN

V

2 * N µ

V

eN

V Observed (13 TeV)

1

35.9 fb

95% CL upper limit

Preliminary

CMS [CMS PAS EXO-17-028]

Probes (sub) TeV-scale heavy Majorana neutrinos with ‘large’ active-sterile mixing.

6

SLIDE 11

Low-scale Seesaw with Large Mixing

Naively, active-sterile neutrino mixing is small for EW-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); Gluza (APPB ’02); de Gouvea ’07; Kersten, Smirnov (PRD ’07); Gavela, Hambye, Hernandez, Hernandez (JHEP ’09); Ibarra, Molinaro, Petcov (JHEP ’10); Adhikari, Raychaudhuri (PRD ’11); Mitra, Senjanovi´ c, Vissani (NPB ’12); BD, Lee, Mohapatra (PRD ’13);...]

7

SLIDE 12

Low-scale Seesaw with Large Mixing

Naively, active-sterile neutrino mixing is small for EW-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); Gluza (APPB ’02); de Gouvea ’07; Kersten, Smirnov (PRD ’07); Gavela, Hambye, Hernandez, Hernandez (JHEP ’09); Ibarra, Molinaro, Petcov (JHEP ’10); Adhikari, Raychaudhuri (PRD ’11); Mitra, Senjanovi´ c, Vissani (NPB ’12); BD, Lee, Mohapatra (PRD ’13);...]

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.

7

SLIDE 13

Low-scale Seesaw with Large Mixing

Naively, active-sterile neutrino mixing is small for EW-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); Gluza (APPB ’02); de Gouvea ’07; Kersten, Smirnov (PRD ’07); Gavela, Hambye, Hernandez, Hernandez (JHEP ’09); Ibarra, Molinaro, Petcov (JHEP ’10); Adhikari, Raychaudhuri (PRD ’11); Mitra, Senjanovi´ c, Vissani (NPB ’12); BD, Lee, Mohapatra (PRD ’13);...]

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. But the steriles with large mixing are ‘quasi-Dirac’ with suppressed LNV. Generic requirement in order to satisfy neutrino oscillation data and 0νββ

constraints. [Abada, Biggio, Bonnet, Gavela, Hambye (JHEP ’07); Ibarra, Molinaro, Petcov (JHEP ’10);

Fernandez-Martinez, Hernandez-Garcia, Lopez-Pavon, Lucente (JHEP ’15); Drewes, Garbrecht, Gueter, Klaric (JHEP ’16)]

Should also look for lepton number conserving channels at the LHC.

7

SLIDE 14

Inverse Seesaw

Provides a (technically) natural low-scale seesaw framework. Two sets of SM-singlet fermions with opposite lepton numbers. [Mohapatra, Valle (PRD ’86)] −LY ⊃ YνLφcN + MNSN + 1 2µSSSc + H.c. mν ≃ (MDM−1

N ) µS (MDM−1 N )T

Naturally allows for large mixing: VℓN ≃

mν

µS ≈ 10−2

1 keV

µS

8

SLIDE 15

Inverse Seesaw

Provides a (technically) natural low-scale seesaw framework. Two sets of SM-singlet fermions with opposite lepton numbers. [Mohapatra, Valle (PRD ’86)] −LY ⊃ YνLφcN + MNSN + 1 2µSSSc + H.c. mν ≃ (MDM−1

N ) µS (MDM−1 N )T

Naturally allows for large mixing: VℓN ≃

mν

µS ≈ 10−2

1 keV

µS But again quasi-Dirac heavy neutrinos. Should look for both lepton number conserving and violating channels at the LHC. Ratio of same-sign to opposite-sign dilepton signal could test the Majorana vs. Dirac nature. [Gluza, Jelinski (PLB ’15); BD, Mohapatra (PRL ’15); Gluza, Jelinski, Szafron (PRD ’16); Anamiati,

Hirsch, Nardi (JHEP ’16); Das, BD, Mohapatra (PRD ’17)]

8

SLIDE 16

Heavy (Pseudo) Dirac Neutrinos at the LHC

[del Aguila, Aguilar-Saavedra (PLB ’09; NPB ’09); Chen, BD (PRD ’12); Das, Okada (PRD ’13); Das, BD, Okada (PLB ’14); Izaguirre, Shuve (PRD ’15); Dib, Kim (PRD ’15); Dib, Kim, Wang (PRD ’17; CPC ’17); Dube, Gadkari, Thalapillil (PRD ’17)]

Trilepton plus / ET

q ¯ q′ W + l+ N l− W + l+ ν

1 10

2

10

3

10

(GeV)

N

m

5 −

10

4 −

10

3 −

10

2 −

10

1 −

10 1

2

|

eN

|V

95% CL upper limits Expected 2 std. deviation ± 1 std. deviation ± Observed decays prompt N Observed, DELPHI prompt DELPHI long-lived L3 ATLAS CMS 8 TeV

CMS

(13 TeV)

1

35.9 fb

1 10

2

10

3

10

(GeV)

N

m

5 −

10

4 −

10

3 −

10

2 −

10

1 −

10 1

2

|

N µ

|V

95% CL upper limits Expected 2 std. deviation ± 1 std. deviation ± Observed decays prompt N Observed, DELPHI prompt DELPHI long-lived CMS 8 TeV ATLAS

CMS

(13 TeV)

1

35.9 fb

2 2 [CMS Collaboration, Phys. Rev. Lett. 120, 221801 (2018)]

9

SLIDE 17

Importance of VBF for Heavy Neutrino Production

[BD, Pilaftsis, Yang (PRL ’14); Alva, Han, Ruiz (JHEP ’15); Degrande, Mattelaer, Ruiz, Turner (PRD ’16); Das, Okada (PRD ’16)]

200 400 600 800 1000

[fb]

2



N l

V  X) / N → (pp σ 1 10

2

10

3

10

4

10

NLO

±

l N

NLO

ν N +1j - NLO

±

l N j - VBF NLO

±

l N +0,1j - GF LO ν N

14 TeV LHC

[GeV]

N

Heavy Neutrino Mass, m

200 400 600 800 1000

LO

σ /

NLO

σ

0.8 1 1.2 1.4

[Cai, Han, Li, Ruiz (Front. in Phys. ’18)]

10

SLIDE 18

Higgs Decay

[BD, Franceschini, Mohapatra (PRD ’12); Cely, Ibarra, Molinaro, Petcov (PLB ’13)]

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 decay 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 ( 1 4 T e V ) (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)

[Das, BD, Kim (PRD ’17)]

11

SLIDE 19

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, 1411.5230]

Can access the region for successful leptogenesis via heavy neutrino oscillations.

12

SLIDE 20

Displaced Vertex Search

q' q N W +

+ +

W q q V N V N '

HL-LHC FCC-hh/SppC 20 40 60 80 100 10-11. 10-10. 10-9. 10-8. M [GeV] |

2

[Antusch, Cazzato, Fischer (IJMPA ’17)]

Δ Δ 13

SLIDE 21

Displaced Vertex Search

q' q N W +

+ +

W q q V N V N '

HL-LHC FCC-hh/SppC 20 40 60 80 100 10-11. 10-10. 10-9. 10-8. M [GeV] |

2

[Antusch, Cazzato, Fischer (IJMPA ’17)] [Kling, Trojanowski (PRD ’18)] | |

Δ

A|UeN| 10-1 1 10 10-5 10-4 10-3 10-2

FASER Lmax=480m, Δ=10m Lint=3 ab-1 R = 1 m R = 2 c m

DUNE NA62 SHiP

mN [GeV]

13

SLIDE 22

Displaced Vertex Search

q' q N W +

+ +

W q q V N V N '

HL-LHC FCC-hh/SppC 20 40 60 80 100 10-11. 10-10. 10-9. 10-8. M [GeV] |

2

[Antusch, Cazzato, Fischer (IJMPA ’17)] [Kling, Trojanowski (PRD ’18)] | |

Δ

A|UeN| 10-1 1 10 10-5 10-4 10-3 10-2

FASER Lmax=480m, Δ=10m Lint=3 ab-1 R = 1 m R = 2 c m

DUNE NA62 SHiP

mN [GeV]

100 101

mN (GeV)

10−13 10−12 10−11 10−10 10−9 10−8 10−7 10−6 10−5 10−4

|UeN|2

[MATHUSLA Collaboration ’18] [see Wednesday plenary talks by D. Curtin and J. Feng]

13

SLIDE 23

Summary of Constraints and Prospects 0.1 1 10 100 1000 10-11 10-9 10-7 10-5 0.001 0.100 MN (GeV) VeN

2 B B N Seesaw DELPHI L3 LEP2 ATLAS8 C M S 1 3 SHiP FCC-ee 0νββ EWPD ILC K→eν π→eν PS191 K→eeπ Belle CHARM NA3 JINR DUNE CMS13trilepton

[Atre, Han, Pascoli, Zhang (JHEP ’09); Deppisch, BD, Pilaftsis (NJP ’15)]

14

SLIDE 24

Interference Effect

[Hernandez, Jones-Perez, Suarez-Navarro (EPJC ’19); Bolton, Deppisch, BD (to appear)]

15

SLIDE 25

New Gauge Bosons

(W ′, Z ′)

16

SLIDE 26

U(1)X Extension

[Buchmuller, Greub (NPB ’91); Fileviez Perez, Han, Li (PRD ’09); Kang, Ko, Li (PRD ’15); Heeck, Teresi (PRD ’16); BD, Mohapatra, Zhang (JHEP ’17); Das, Okada, Raut (EPJC ’18); Cox, Han, Yanagida (JHEP ’18); ...]

Z l

 

 d

l

− β

 u q  q

N

d u

W

−

q  q

N W

− '

17

SLIDE 27

U(1)X Extension

[Buchmuller, Greub (NPB ’91); Fileviez Perez, Han, Li (PRD ’09); Kang, Ko, Li (PRD ’15); Heeck, Teresi (PRD ’16); BD, Mohapatra, Zhang (JHEP ’17); Das, Okada, Raut (EPJC ’18); Cox, Han, Yanagida (JHEP ’18); ...]

Z l

 

 d

l

− β

 u q  q

N

d u

W

−

q  q

N W

− '

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{{ [Deppisch, Desai, Valle (PRD ’14)]

17

SLIDE 28

U(1)X Extension

[Buchmuller, Greub (NPB ’91); Fileviez Perez, Han, Li (PRD ’09); Kang, Ko, Li (PRD ’15); Heeck, Teresi (PRD ’16); BD, Mohapatra, Zhang (JHEP ’17); Das, Okada, Raut (EPJC ’18); Cox, Han, Yanagida (JHEP ’18); ...]

Z l

 

 d

l

− β

 u q  q

N

d u

W

−

q  q

N W

− '

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{{ [Deppisch, Desai, Valle (PRD ’14)]

One of the RHNs can be made a dark matter candidate. [see parallel talk by S. Okada]

17

SLIDE 29

Left-Right Symmetric Extension

[Keung, Senjanovi´ c (PRL ’83); Ferrari et al (PRD ’00); Nemevsek, Nesti, Senjanovi´ c, Zhang (PRD ’11); Das, Deppisch, Kittel, Valle (PRD ’12); Mitra, Ruiz, Scott, Spannowsky (PRD ’16);...]; see Tuesday plenary talk by G. Senjanovi´ c

New contribution to same-sign dilepton signal (independent of mixing)

q ¯ q′ W +

R

ℓ+ N ℓ+ W −

R

j j

18

SLIDE 30

Left-Right Symmetric Extension

[Keung, Senjanovi´ c (PRL ’83); Ferrari et al (PRD ’00); Nemevsek, Nesti, Senjanovi´ c, Zhang (PRD ’11); Das, Deppisch, Kittel, Valle (PRD ’12); Mitra, Ruiz, Scott, Spannowsky (PRD ’16);...]; see Tuesday plenary talk by G. Senjanovi´ c

New contribution to same-sign dilepton signal (independent of mixing)

q ¯ q′ W +

R

ℓ+ N ℓ+ W −

R

j j

[TeV]

R

W

m [TeV]

R

N

m

ATLAS

1

=13 TeV, 36.1 fb s 95% CL limit channel ee ,

R

N Majorana

L

g =

R

g

Obs.

Exp. SS only

Obs.

Exp. OS only

Obs.

Exp. Combined

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 1 2 3 4 5

(a) [TeV]

R

W

m [TeV]

R

N

m

ATLAS

1

=13 TeV, 36.1 fb s 95% CL limit channel µ µ ,

R

N Majorana

L

g =

R

g

Obs.

Exp. SS only

Obs.

Exp. OS only

Obs.

Exp. Combined

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 1 2 3 4 5

(b)

[ATLAS Collaboration, JHEP 1901, 016 (2019)]

18

SLIDE 31

Future Prospects

[]

[]

> () (=/) + / ( ) + / (=/) () () + (+)

(=/)
(
)

[

]
[Nemevsek, Nesti, Popara (PRD ’18)]

19

SLIDE 32

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

[Chen, BD, Mohapatra (PRD ’13); BD, Kim, Mohapatra (JHEP ’16)]

20

SLIDE 33

CPV in the RHN Sector

Ne

Nµ

=
cos θR

sin θRe−iδR − sin θReiδR cos θR N1 N2

.

Same sign charge asymmetry : Aαβ ≡ N(ℓ+

αℓ+ β) − N(ℓ− α ℓ− β )

N(ℓ+

αℓ+ β) + N(ℓ− α ℓ− β ) .

αβ

μμ μ μμ μ

αβ

μμ μ μμ μ

αβ

μ μ μ μ μ μ θ π δ π 

21

SLIDE 34

CPV in the RHN Sector

Ne

Nµ

=
cos θR

sin θRe−iδR − sin θReiδR cos θR N1 N2

.

Same sign charge asymmetry : Aαβ ≡ N(ℓ+

αℓ+ β) − N(ℓ− α ℓ− β )

N(ℓ+

αℓ+ β) + N(ℓ− α ℓ− β ) .

4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0

0.4
0.2

0.0 0.2 0.4 0.6 0.8 1.0

WR mass [TeV] αβ LHC14

current LHC limit w/o CPV [ee, μμ & eμ] w/ CPV [ee] w/ CPV [μμ] w / C P V [ e μ ] 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0

0.2

0.0 0.2 0.4 0.6 0.8 1.0

WR mass [TeV] αβ HE-LHC

current LHC limit w/o CPV [ee, μμ & eμ] w / C P V [ e e ] w/ CPV [μμ] w/ CPV [eμ] 5 10 15 20 25 30

0.2

0.0 0.2 0.4 0.6 0.8 1.0

WR mass [TeV] αβ FCC-hh

current LHC limit w /

C

P V [ e e , μ μ & e μ ] w/ CPV [ee] w / C P V [ μ μ ] w / C P V [ e μ ] θ π δ π 

21

SLIDE 35

CPV in the RHN Sector

Ne

Nµ

=
cos θR

sin θRe−iδR − sin θReiδR cos θR N1 N2

.

Same sign charge asymmetry : Aαβ ≡ N(ℓ+

αℓ+ β) − N(ℓ− α ℓ− β )

N(ℓ+

αℓ+ β) + N(ℓ− α ℓ− β ) .

4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0

0.4
0.2

0.0 0.2 0.4 0.6 0.8 1.0

WR mass [TeV] αβ LHC14

current LHC limit w/o CPV [ee, μμ & eμ] w/ CPV [ee] w/ CPV [μμ] w / C P V [ e μ ] 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0

0.2

0.0 0.2 0.4 0.6 0.8 1.0

WR mass [TeV] αβ HE-LHC

current LHC limit w/o CPV [ee, μμ & eμ] w / C P V [ e e ] w/ CPV [μμ] w/ CPV [eμ] 5 10 15 20 25 30

0.2

0.0 0.2 0.4 0.6 0.8 1.0

WR mass [TeV] αβ FCC-hh

current LHC limit w /

C

P V [ e e , μ μ & e μ ] w/ CPV [ee] w / C P V [ μ μ ] w / C P V [ e μ ] 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 θR/π 2 δR/π ee @ FCC-hh [WR = 15 TeV]

0.8 0.6 0.4 0.2 leptogenesis leptogenesis

[BD, Mohapatra, Zhang, 1904.04787] 21

SLIDE 36

New Scalars

22

SLIDE 37

L-R Seesaw Higgs Sector

=

φ0

1

φ+

2

φ−

1

φ0

2

,

R =

+

R

√ 2 ++ R R

−

+ R

√ 2

,

L =

+

L

√ 2 ++ L L

−

+ L

√ 2

R ≡ vR gives rise to RH Majorana neutrino masses, and hence, type-I seesaw.

L ≡ vL gives rise to a type-II seesaw contribution.

14 physical scalar fields (compared to just 1 in the SM). Very rich phenomenology.

[Gunion, Grifols, Mendez, Kayser, Olness (PRD ’89); Polak, Zralek (PLB ’92); Akeroyd, Aoki (PRD ’05); Fileviez Perez, Han, Huang, Li, Wang (PRD ’08); Bambhaniya, Chakrabortty, Gluza, Kordiaczy´ nska, Szafron (JHEP ’14); Dutta, Eusebi, Gao, Ghosh, Kamon (PRD ’14); Maiezza, Nemevsek, Nesti (PRL ’15); BD, Mohapatra, Zhang (JHEP ’16);...]

23

SLIDE 38

Bidoublet Sector

FCNC constraints require the bidoublet scalars (H0

1, A0 1, H± 1 ) to be very heavy

15 TeV. [An, Ji, Mohapatra, Zhang (NPB ’08); Bertolini, Maiezza, Nesti (PRD ’14)]

H1

0, A1

H1

0, A1

d s s d s d s d

No hope for them at the LHC. Need a 100 TeV collider! [see Monday plenary talk by T. Han]

24

SLIDE 39

Neutral Triplet Sector

Hadrophobic and allowed to be light (down to sub-GeV scale) by current constraints. Suppressed coupling to SM particles (either loop-level or small mixing). Necessarily long-lived at the LHC, with displaced vertex signals. Clean LFV signals at future lepton colliders.

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 C H A R M [ K ] D U N E [ K ] CHARM [B] S H i P [ B ] K0 mixing Bd mixing Bs mixing LHC LLP searches MATHUSLA FCC LLP searches FCC forward detector

μ

→

μ

→ μμ

τ

⟶

→ ττ 10 100 1000 10-3 10-2 0.1 1

mH [GeV] |hμτ|

(g-2)μ (g-2)μ excluded CEPC ILC

p

[BD, Mohapatra, Zhang (PRD ’17; NPB ’17)] [BD, Mohapatra, Zhang (PRL ’18; PRD ’18)]

25

SLIDE 40

Charged Triplet Sector

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

[CMS-PAS-HIG-16-036]

26

SLIDE 41

Prospects at e−p Collider

p j γ, Z e+ e− H−− p e− W ± ν H−− j Process − I Process − II p j γ, Z H−− H−− e− e+ p j W − W − H−− e− ν

LEP Bound LHC 13 TeV Bound ∫ L dt = 3 ab-1

3 σ 2 σ

Signal - I YΔ

ee

0.2 0.4 0.6 0.8 1

MH-- [GeV]

750 1000 1250 1500 1750 2000

LEP Bound LHC 13 TeV Bound ∫ L dt = 3 ab-1

3 σ 2 σ

Signal - II YΔ

ee

0.2 0.4 0.6 0.8 1

MH-- [GeV]

750 1000 1250 1500 1750 2000

27

SLIDE 42

Prospects at e−p Collider

p j γ, Z e+ e− H−− p e− W ± ν H−− j Process − I Process − II p j γ, Z H−− H−− e− e+ p j W − W − H−− e− ν

LEP Bound LHC 13 TeV Bound ∫ L dt = 3 ab-1

3 σ 2 σ

Signal - I YΔ

ee

0.2 0.4 0.6 0.8 1

MH-- [GeV]

750 1000 1250 1500 1750 2000

LEP Bound LHC 13 TeV Bound ∫ L dt = 3 ab-1

3 σ 2 σ

Signal - II YΔ

ee

0.2 0.4 0.6 0.8 1

MH-- [GeV]

750 1000 1250 1500 1750 2000

[BD, Khan, Mitra, Rai, 1903.01431]

27

SLIDE 43

Zee Model

hH0

1i

H+

2

η+ νi lk lc

k

νj

28

SLIDE 44

Zee Model

hH0

1i

H+

2

η+ νi lk lc

k

νj

e− e+ h+ h− Z/γ e− e+ νe h− h+ e+ e− W + h− 28

SLIDE 45

Zee Model

hH0

1i

H+

2

η+ νi lk lc

k

νj

e− e+ h+ h− Z/γ e− e+ νe h− h+ e+ e− W + h−

(yαe = 0) (yαe = 1)

[Babu, BD, Jana, Thapa (to appear); see Tuesday parallel talk by K. S. Babu]

28

SLIDE 46

RPV SUSY

WRPV = µiHuLi + 1 2λijkLiLjEc

k + λ′ ijkLiQjDc k + 1

2λ′′

ijkUc i Dc j Dc k [Hall, Suzuki (NPB ’84); Babu, Mohapatra (PRL ’90)]

29

SLIDE 47

RPV SUSY

WRPV = µiHuLi + 1 2λijkLiLjEc

k + λ′ ijkLiQjDc k + 1

2λ′′

ijkUc i Dc j Dc k [Hall, Suzuki (NPB ’84); Babu, Mohapatra (PRL ’90)]

29

SLIDE 48

RPV SUSY

WRPV = µiHuLi + 1 2λijkLiLjEc

k + λ′ ijkLiQjDc k + 1

2λ′′

ijkUc i Dc j Dc k [Hall, Suzuki (NPB ’84); Babu, Mohapatra (PRL ’90)]

Recent interest in light of the B-anomalies. [Deshpande, He (EPJC ’17); Altmannshofer, BD, Soni

(PRD ’17); Das, Hati, Kumar, Mahajan (PRD ’17); Earl, Gregoire (JHEP ’18); Trifinopoulos (EPJC ’18)] – see Friday plenary talk by X.-G. He

Can also address the ANITA anomalous events. [Collins, BD, Sui (PRD ’19); see Tuesday parallel

talk by Y. Sui]

29

SLIDE 49

Conclusion

Understanding the neutrino mass mechanism will provide important insights into the BSM world. Current and future colliders provide a ripe testing ground for low-scale neutrino mass models. Can probe the messenger particles (new fermions/gauge bosons/scalars) in a wide range of parameter space. Healthy complementarity at the intensity frontier. Could shed light on other outstanding puzzles, such as the matter-antimatter asymmetry and dark matter.

30

SLIDE 50

Conclusion

Understanding the neutrino mass mechanism will provide important insights into the BSM world. Current and future colliders provide a ripe testing ground for low-scale neutrino mass models. Can probe the messenger particles (new fermions/gauge bosons/scalars) in a wide range of parameter space. Healthy complementarity at the intensity frontier. Could shed light on other outstanding puzzles, such as the matter-antimatter asymmetry and dark matter.

30