DirectDetec(onofDarkPhoton

HaipengAn(Caltech)

UCLADarkMa;er2016

Whatisdarkphoton?

•  Lagrangian

• 

• 

L = �14V µ⌫Vµ⌫ +

1

2m2V V

µVµ �1

2V µ⌫Fµ⌫

mV < 1 MeVV ! 3�

The dark photon can easily be cosmologically stable, and play the roll of dark matter. mV > 1 MeV

V ! e+e�

�V /2↵4m9V

m8e

The dark photon plays the roll of the mediator of the force of dark matter self interaction.

X

Sourcesofdarkphoton

•  Natural sources – The Sun – Dark matter surround us if it composes the dark matter

•  Man-made sources – From laser beam (LSW) – From antennas (CROWS) – Various colliders (for heavy dark photon)

•  Signal rate

– Total absorption rate; – Solar flux; – Branching ratio to desired signals.

Branchingra(otothedesiredsignal.

Totalabsorp(onrate

FluxfromtheSun

Solardarkphoton

Sun Earth

Darkphoton,V

Solardarkphoton

•  Resonant production conditions – Transverse mode: – Longitudinal mode:

•  Inside the Sun

Solardarkphoton

mV = !p! = !p

!p : plasma frequency

! : energy of dark photon

mV : mass of dark photon

1 eV < !p < 300 eV

HA,M.Pospelov,J.Pradler1302.3884&PLB

�L dominates if mV . 10 eV�T dominates if 10 eV . mV . 300 eV

Solardarkphoton

! ⇡ !p , 1 eV < !p < 300 eV

The detector should be able to detect ~ 100 eV energy deposition.

HA,M.Pospelov,J.Pradler1309.6599

300eV

Solardarkphoton

PMT PMT PMT PMT

PMT PMT PMT PMT

E

E

V

X A(*)

Xenonliquid

Xenongas

e-

Xenonatom

photons

•  We are looking at electron recoils.

•  Up to now only XENON10 collaboration has published the result in this energy region.

Solardarkphoton

•  XENON10 S2 only analysis

• 

Numberofelectrons

300eV~25electrons

Photo-ionization dominates.

XENON101104.3088

XENON10constraint

HA,M.Pospelov,J.Pradler1304.3461&PRL

ConstraintfromB8neutrinofromthecenteroftheSun.

HA,M.Pospelov,J.Pradler1302.3884&PLB

•  Coherent oscillation

•  Generated during inflation – Transverse modes cannot be generated due to conformal

invariance – Longitudinal mode, OK

Darkphotondarkma;er

1

2m2V V

2

Graham,Mardon,Rajendran1504.02102

Darkphotondarkma;er

PMT PMT PMT PMT

PMT PMT PMT PMT

E

E

V

X A(*)

Xenonliquid

Xenongas

e-

Xenonatom

photons

•  Nonrelativistic

•  Can be detected by XENON detector if .

•  Use S2 only analysis

•  Use S1 + S2 analysis

v ⇠ 10�3 ! ⇡ mV

mV > 12 eV

if mV < 1 keV

if mV > 1 keV

S1photons

Darkphotondarkma;er

HA,M.Pospelov,J.Pradler,A.Ritz1412.8378HA,M.Pospelov,J.Pradler,A.Ritz,K.Ni1510.04530

Heavydarkphotonasadarkforce

•  How to know the dark photon is the mediator of dark matter self interaction?

•  If the self interaction is strong enough, the dark matter can form a bound state.

•  We propose to use the high luminosity B factories to search for dark bound states.

HeavydarkphotonasadarkforceHA,B.Echenard,M.Pospelov,Y.Zhang1510.05020

Hg- 2Le

E744

E141

Orsay

U70

CHARM

Hg - 2Lm Dark photonûBABARNA48 ê 2

hD and UDûBABAR

future B factory

nobound

states

Hcurrent limit, aD=0.25L

Hcurrent limit, aD=0.5LHfuture limit, aD=0.25L

Hfuture limit, aD=0.5L

0.005 0.01 0.02 0.05 0.1 0.2 0.5 1. 210-6

10-5

10-4

0.001

0.01

mV HGeVL

k

mD = 3.5 GeV

Summaryandoutlook

•  mV < 1 MeV – Dark matter detectors (sensitive to electron recoils) can be used

to detect both solar dark photon and dark photon dark matter. –  To detect sub-keV energy dark photon, we need to further

understand the S2 background of the detectors. –  In principle, all the detectors designed for detecting axion dark

matter can be used to detect dark photon dark matter •  Microwave cavity (ADMX PRL 105,171801) •  LC circuit (proposed by Chaudhuri, Graham, Irwin 1411.7382) •  NMR •  …

Summaryandoutlook

•  mV > 1 MeV –  If the dark matter can form bound state, we can use high

luminosity colliders to study the property of dark matter bound state. •  Belle II •  SeaQuest •  SHiP

Backup

Solardarkphoton

•  Scalingwiththemass

– Produc(onrate

– Absorp(onrate

mV ⌧ !p

�T / (mV /!p)4 , �L / (mV /!p)2 ,

m2V ⌧ |(✏r � 1)!2|

�T / [m2V /|(✏r � 1)!2|]2 , �L / m2V /|(✏r � 1)!2| ,