Neutrino Portal Dark Matter Barmak Shams Es Haghi U.Pittsburgh/U. - - PowerPoint PPT Presentation

Neutrino Portal Dark Matter

Barmak Shams Es Haghi U.Pittsburgh/U. Utah

Searching for New Physics, U.Utah

August 5, 2019

with Brian Batell, Tao Han, David McKeen

The Standard Model of Elementary Particles

successfully describes the particles and their interactions.

Last triumph: Higgs discovery in 2012

But there are still some issues:

• Dark matter
• Neutrino mass
• Naturalness
• …

All involve beyond the SM physics

1

Dark Matter (Gravitational Evidence):

• Rotation Curves
• CMB
• Structure Formation
• Gravitational lensing

2

Properties

• Stable (life time > age of the universe)
• Dark/Dissipationless
• Collisionless

bullet cluster: on Mps scales, no interaction

• Cannot be arbitrarily light, otherwise QM get in the way

⇣ σ 10−24cm2 ⌘ ✓1GeV mDM ◆ ≤ 1

Non-gravitational Interaction?

3

Non-gravitational Interaction of DM: Renormalizable Portals

• Scalar portal
• Vector portal
• Neutrino portal

Motivations For Neutrino Portal:

• Explains neutrino mass (via seesaw mechanism)
• Less well-studied portal to the Dark Sector
• Dark Matter

(λ1S+λ2S2)|H|2 BµνV µν LHN

4

Typical Seesaw: L ⊃ −1 2mNNN − yLHN − λNφχ + h.c.

Diagonalizing the mass matrix

light neutrino, heavy neutrino, and mixing angle:

1 − U 2

mχ > mN

∼

mχ < mN

∼

U 2

5

Secluded regime Direct annihilation to SM U ∼ yv mN ∼ r mν mN ∼ 10−5 × ⇣ mν 0.05eV ⌘1/2 ✓GeV mN ◆1/2

Direct annihilation to light neutrinos is inefficient

hσvi = h Re(λ)2(mχ + mN) + Im(λ)2(mχ mN) i2 16π[m2

φ + m2 χ m2 N]2

✓ 1 m2

N

m2

χ

◆1/2

Parameters: {λ, mφ, mχ, mN}

! {hσvi, mχ, mN}

Relic Abundance & Cosmology:

hσvithermal = 2.2 ⇥ 10−26 cm3 s−1

hσvi ⇠ hσvithermal

Mass range: Unitarity + Thermal WIMP + BBN

1 GeV < mN < mχ . 20 TeV

Thermal equilibrium: 6

mν ∼ p (∆mν)atm ∼ 0.05 eV →

y ' 10−6 ⇣ mN 246 GeV ⌘1/2

Yukawa coupling is small, Direct Detection/Production at Collider are challenging.

Secluded regime

mχ > mN

Indirect Detection:

DM can have multiple annihilation channels

Quantity of interest:

Image Credit: Sky & Telescope / Gregg Dinderman

Energy spectrum per DM annihilation in the photon, electron,… channels

Spectrum Simulation

7

signature of DM: an excess of the final stable particles

• ver the astrophysical background

Simulation Chain:

SM_HeavyN_NLO Model Files (SM+ 3 heavy neutrinos)

MadGraph5_aMC@NLO (Generating Events) Pythia (Hadronize + Shower)

dNa,f dEa

χχ→ χ = = = =

• []
• / []

χχ→ χ = = = =

• γ []

γ

γ/γ []

γ

Alva, Han, Ruiz 2015 Degrande, Mattelaer, Ruiz , Turner 2016

(Spectrum)

8

χχ→ χ = = = =

• _ []
• _
• _/

CMB

e− + p ⌦ H + γ

Z ~1100

DM annihilation products: electron/positron & photon: heating and ionization occurs primarily through them

binding energy : 13.6 eV

✓ dE dV dt ◆

injected

= ρ2

DM(z) hσvi

mDM = (1 + z)6ρ2

critΩ2 DM,0

hσvi mDM

✓ dE dV dt ◆

deposited

= f(z) ✓ dE dV dt ◆

injected

feff(mDM) hσvi mDM < 4.1 ⇥ 10−28cm3/s/GeV

Planck limit:

Ade et al. ,2016

9

〈σ〉 〈σ〉 λ [ϕ = χ]

• π

χ =

• χ []

[]

% 10

Gamma rays from dwarf spheroidal galaxies (dSphs)

very clean sources for indirect detection:

• Large DM content
• Having few stars and little gas, negligible background

6 years of Fermi Large Area Telescope (LAT) data: The Fermi analysis is based on a joint maximum likelihood analysis of 15 dSphs for gamma ray energies in the 500 MeV - 500 GeV range.

dΦa dEa = 1 4⇡ hannvi 2m2

DM

X

f

dNa,f dEa Bf ⇥ Z

V

⇢2

DM(~

x) dV Flux

Particle Physics

Astrophysics (J - factor) 11

Given that no significant excess is observed, a delta-log-likelihood method is used to set limits on DM model parameters.

〈σ〉 〈σ〉 λ [ϕ = χ]

• π

χ =

• χ []

[]

% 12

Antiprotons

Antiproton content of the astrophysical background is rare:

• its production costs us a lot of energy
• energy flux of cosmic rays is very steep peaked around 0.1 GeV

DM annihilation will produce as much antiproton as proton!

Antiprotons deflection by the Galactic magnetic field and their propagation may be seen as a diffusion process.

The Alpha Magnetic Spectrometer (AMS-02) has provided the most precise measurements of the cosmic ray proton and antiproton flux to date. 13

∼ 7 mP

Used Einasto profile & the MED propagation scheme

χ2(mχ, hσvi) χ2

0  4

is the best fit assuming no primary DM antiproton source

χ2

Giesen, et al. 2015

14

χχ→ χ = = = =

• _ []
• _
• _/

_ []

〈σ〉 〈σ〉 λ [ϕ = χ]

• π

χ =

• χ []

[]

15

Galactic Center Gamma Ray Excess Interpretation

Calore, Cholis, Weniger 2014

χ =

• χ []

[]

• ● ● ● ●
• ● ●
• -
• - - - -
• -
• -
• - - - -
• -
• χχ→

χ= =

• γ []

γΦγ [/()]

• -

         hσvi = 3.08 ⇥ 10−26 cm3 s−1 mχ = 41.3 GeV mN = 22.6 GeV χ2/dof = 14.12/23

16

Goodenough, Hooper 2009

Various analyses of Fermi-LAT data show an excess

• f gamma rays coming from the central region of the Milky Way

best-fit point

• 〈σ〉=⨯-
• χ

=

• χ []

[]

Einasto & MAX Burkert & MED log10(Jk) = log10( ¯ Jk) − 2σk

log10(Jk) = log10( ¯ Jk) + 2σk

GC excess

17

Typical Seesaw: L ⊃ −1 2mNNN − yLHN − λNφχ + h.c.

Diagonalizing the mass matrix

light neutrino, heavy neutrino, and mixing angle:

1 − U 2

mχ > mN

∼

mχ < mN

∼

U 2

18

Secluded regime Direct annihilation to SM U ∼ yv mN ∼ r mν mN ∼ 10−5 × ⇣ mν 0.05eV ⌘1/2 ✓GeV mN ◆1/2

Direct annihilation to light neutrinos is inefficient

mχ < mN

hσvi = y4U 4 32π m2

χ

m4

φ

1 + m2

χ

m2

φ

!−2 ⇠ 3 ⇥ 10−26 cm3 s ✓yU 0.2 ◆4 ⇣ mχ 10GeV ⌘−2 ✓mφ/mχ 3 ◆−4

Thermal WIMP demands large mixing angle!

Dirac Neutrino Portal:

−L ⊃ m2

φ|φ|2 + mχχχ + mNNN + [λlLl ˜

HNR + φχ(yLNL + yRNR) + h.c.]

Direct annihilation to SM

19

Bertoni, Ipek, McKeen, & Nelson 1412.3113 Batell, Han, McKeen, & BSE 1709.07001

Approximate lepton number symmetry allows for light SM neutrinos even if the Yukawa coupling (and active sterile mixing) is large

ν4 = ✓ U ∗

N4NL + P ` U ∗ `4ν`L

NR ◆

U`4 = λ`v m4

|UN4| = mN m4 = s 1 − X

`

|U`4|2

Large mixing allows for a sizable DM - SM neutrino coupling

yLφχRNL + h.c. → yL |UN4| φχRν4L − yL q 1 − |UN4|2φχRνlL + h.c.

Invisible Sterile Neutrino:

τ→νμν τ→νπ

• νμ→ντ

→ →

• ()

|τ π→μν

• →μν

τμ/ →μν

→

→ →μ

• |μ

π→ν τμ/

• π → ν

π → μν →ν

→ → →

→ν

• |

µ decay : nonvanishing |Ue4| and/or |Uµ4| → modified GF → affects measuring CKM Lack of distortion in e+ energy spectrum in µ+ decay

τ : leptonic and hadronic decay neutrino oscillation

BBN : number of relativistic species

Invisible Higgs and Z decays

20

mN > mφ, mχ

Sterile Neutrino constraints Cont.:

Rare meson decays

M + l+

ν4

τ→νμν τ→νπ

• νμ→ντ

→ →

• ()

|τ π→μν

• →μν

τμ/ →μν

→

→ →μ

• |μ

π→ν τμ/

• π → ν

π → μν →ν

→ → →

→ν

• |

M + l+ ν∗

l

χ

φ 21

peak in energy spectrum of lepton

like K+ → µ+ + invisible

τ→νμν τ→νπ

• νμ→ντ

→ →

• ()

|τ π→μν

• →μν

τμ/ →μν

→

→ →μ

• |μ

π→ν τμ/

• π → ν

π → μν →ν

→ → →

→ν

• |

Sterile Neutrino constraints, Cont.: l 2U 2

22

LHC searches: Drell-Yan production of W and its mass measurement Heavy neutrino decays invisibly into dark sector, distortion of the kinematics of the decay (kink in lepton pT)

ATLAS 1701.07240

M peak

T

= MW ✓ 1 − m2

4

M 2

W

◆ , ppeak

T

= 1 2M peak

T

Dark Matter Phenomenology

Y ⌘ y4

L

X

i

|Ui4|2 !2 m4

χ

m4

φ

= 32πm2

χhσvi

〈σ〉< ⊙ ⊙ |τ

• =π

|τ

• =
• =
• π
• =
• χ=ϕ/ ()

τ=τ χ

• ϕ
• 〈σ〉<

⊙ ⊙

• →μ+

|μ

• =π

|μ

• =
• =
• π
• =
• μ=μ χ
• ϕ
• 〈σ〉<

⊙ ⊙ |

• =π

|

• =
• =
• π
• =
• = χ
• ϕ
• =χ

〈σ〉< ⊙ ⊙ |τ

• =π

|

• τ
• =- =π

=-

• χ=ϕ/ ()

〈σ〉< ⊙ ⊙

• →μ+

|μ

• =π

|

• μ
• =- =π

=- 〈σ〉< ⊙ ⊙ |

• =π

|

• =- =π

=-

=

23

Direct detection provides a powerful probe of the high Dark Matter mass region

Direct Detection: spin independent scattering off nuclei via Z Recent: XENON1T, PandaX-II Future : SuperCDMS SNOLAB Neutrino floor

DM Structure: Missing satellite problem: observation of fewer satellite galaxies of the Milky Way than expected

Possible solution: Relatively strong coupling between Dark matter and light neutrinos produces a pressure agains gravity suppressing the Formation of structures smaller than horizon size at DM kinetic decoupling

→ →

24

Late kinetic decoupling leads to a lower bound on mass of gravitationally bound objects

M > Mcutoff = 108Msolar ✓ Td keV ◆−3

Cutoff mass:

below which structures do not efficiently form

Mcut ' 108M ⇣ g⇤ 3.36 ⌘7/8 ✓0.1 GeV mχ ◆14/4 Y 3/4

〈σ〉<

• ⊙
• ⊙

|τ

• =π

|τ

• =-

=π =-

• χ=ϕ/ ()

τ=τ χ

• ϕ
• 〈σ〉<
• ⊙
• ⊙
• →μ+

|μ

• =π

|μ

• =-

=π =-

• μ=μ χ
• ϕ
• 〈σ〉<
• ⊙
• ⊙

|

• =π

|

• =-

=π =-

• = χ
• ϕ
• =χ

〈σ〉<

• ⊙
• ⊙

|τ

• =π

|τ

• =- =π

=-

• χ=ϕ/ ()

〈σ〉<

• ⊙
• ⊙
• →μ+

|μ

• =π

|μ

• =- =π

=- 〈σ〉<

• ⊙
• ⊙

|

• =π

|

• =- =π

=-

=

107M 6 Mcut 6 109M

25

Bertoni, Ipek, McKeen, & Nelson 1412.3113

Summary

• Neutrino portal is an economical, predictive and less well-studied

model to explain thermal WIMP DM.

• Rich phenomenology
• Secluded regime is difficult to probe in general, indirect detection
• ffers a handle
• Efficient direct annihilation is allowed because of approximate lepton

number symmetry

26

Tiank yov!