What Atomic Physics Can Do for Neutrino and Direct Dark

          Matter Detection?

Jiunn-Wei Chen

National Taiwan U.

Collaborators:

Chih-Liang Wu, Chih-Pang Wu (NTU) Chen-Pang Liu, Hsin-Chang Chih (NDHU) Keh-Ning Huang, Hao-Tse Shiao, Hao-Bin Li, Henry T. Wong, Lakhwinder Singh (AS)

Neutrino and Dark Matter are Portals to New Physics

Neutrino: Challenges and Opportunities

• Mass: hierarchy and absolute values• Dirac or Majorana?• CP phase(s)• Sterile neutrinos? • Electromagnetic properties: magnetic moments? Charge

Radius?...

Those are probes of new physics!

5

How neutrino magnetic moment arises in SM?

ii jj

ll

WW

ii jj

ll

WW

Neutrino Magnetic Moment (NMM)

Flavor changing MMFlavor changing MM Flavor unchanging MMFlavor unchanging MM

DiracDirac

MajoranaMajorana ×× (forbiden by CTP)(forbiden by CTP)

○ ○

○

eV 110 19 m

B

A probe of new physics!

Dark Matter (DM)

• Bigger density than the visible Universe• Its existence hints that there might be a dark

sector

Portals to the Dark Sector

• Other dark matter candidates include MACHOs: MAssive Compact Halo Objects WIMPs: Weakly Interacting Massive Particles

Why Atomic Physics?• Energy scales: Atomic (~ eV) Reactor neutrino (~ MeV) WIMP (~ GeV)• Neutrino: NNM atomic ionization signal larger at lower energy

scattering (current Ge detector threshold 0.1 keV) • DM: direct detection, velocity slow (~ 1/1000), max energy 1 keV for

mass 1 GeV DM. • Opportunity: Applying atomic physics at keV (low for nuclear physics

but high for atomic physics)

Neutrino Atomic Ionization

• The complete set of neutrino electromagnetic form factor is can be constrained:

scattering

2/1sin2

2/1

wv

A

g

g

Weak InteractionWeak Interaction

Magnetic momentMagnetic moment

ETme

112

22

eνeν Xe

Should go for low T (energy transfered)!

Two Approximations ---IEquivalent Photon Approx.

• proposed by Henry Wong et al. ( PRL 105 061801)

• photon q2 ～ 0 : relativistic beam or soft photons qμ ～ 0

• several orders of magnitude enhancement

→ tighen the μν constraint with the same set of data

Two Approximations --- II

Free Electron Approx.

• revisited by Voloshin et al. ( PRL 105 201801)

• sum rule and Hydrogen-like calculation

• FEA works well at sub-keV regime

Toy: ν-H atomic ionization, exact result obtained (1307.2857)

Toy: ν-H atomic ionization, exact result obtained (1307.2857)

Two Approximations

Free Electron Approx.

(revisited by Voloshin et.al)Equivalent Photon Approx.

binding momentum of hydrogen: αme↓

18

Ge atomic ionization: ab initio MCRRPA Theory

• MCRRPA: multiconfiguration relativistic random phase approx.

Reducing the N-body problem to a 1-body problem by solving the 1-body effective potential self consistently.

Hartree-Fock :

RPA:

RRPA:

MCRRPA:

↓Including 2 particle 2 hole excitations

↓Correcting the relativistic effect

↓More than one configurations in Hartree-Fock; Important for open shell system like Ge where the energy gap is smaller than the closed shell case

MCRRPA Theory

( ) ( )t H V t HN-electron relativistic Hamiltonian

↓

Dirac Hamiltonian +Coulomb interaction The rest of EM interaction

Solve initial wavefucntion of atom Solve final wavefunction by time evolution

↓ ↓

Benchmark: Ge Photoionization

Exp. data: Ge solid

Theory: Ge atom (gas)

Above 100 eV error under 5%.

JWC et. al. arXiv: 1311.5294

Ge atomic ionization withab initio MCRRPA Theory

JWC et. al. arXiv: 1311.5294

Ge atomic ionization withab initio MCRRPA Theory

JWC et. al. arXiv: 1311.5294

Ge atomic ionization withab initio MCRRPA Theory

JWC et. al. 1411.0574

JWC et. al. arXiv: 1411.0574

Direct Dark Matter Detection

RPP 2014

What Can Atomic Physics Contribute?

• Light dark matter detection:

• Electron recoil background from solar neutrinos for a LXe detector

• Large LXe detectors can be used as a neutrino/axion detectors as well (measuring NNM w/ a source nearby)

Electron Recoil Background for DARWIN (Lxe)

L. Baudis et al 1309.7024

Summary

• Neutrinos and dark matter particles are portals to new physics

• Ab initio calculations of Ge neutrino atomic ionization performed with 5-10% estimated error. Xe can be done as well.

• Ongoing: dark matter atomic ionization

Searching for the QCD Critical End Point

Jiunn-Wei Chen

National Taiwan U.

JWC, Jian Deng, Lance Labun

1410.5454

Universality• In the scaling region, physics is the same

within the same universality class---an effective field theory argument.

• QCD near CEP ~ Ising model

(Stephanov)

4th momentCPOD 2014

3rd momentCPOD 2014

When the Imaginary is a Real Alternative

Jiunn-Wei Chen

National Taiwan U.

Phys.Rev.Lett. 110 (2013) 262301Collaborators: Jens Braun, Jian Deng, Joaquin E. Drut, Bengt Friman, Chen-Te Ma, Yu-Dai Tsai

From the hottest to the coolest, and back?

When Mr. Berry Meets Mr. Wigner

Jiunn-Wei Chen

National Taiwan U.

JWC, Shi Pu, Qun Wang, Xin-Nian Wang

Phys.Rev.Lett. 110 (2013) 262301

Flavor Structure of the Nucleon Sea from Lattice QCD

Jiunn-Wei Chen

National Taiwan U.

arXiv:1402.1462 [hep-ph]

Collaborators: Huey-Wen Lin, Saul D. Cohen, Xiangdong Ji

Backup slides

Solar Neutrino Flux

40

Case study: NMM• Reactor antineutrino ( )

GEMMA : Ge detector with threshold 1.5keV

TEXONO: Ge detector with threshold 5keV

• Solar neutrino

Borexino

• Astrophysical limit (model dependent)

ee

Be

11109.2

Be

11104.7

B11104.5

B1311 10 to10 from

41

scattering

ee

eνeν Xe

Weak InteractionWeak Interaction Magnetic momentMagnetic moment

How low is low enough?Be

1010•

Now sub-keV Ge detector is available!

Parton Physics on a Euclidean LatticeX. Ji, PRL, 2013

Schematic QCD Phase Diagram

The location of the critical point (CEP)is still unknown.Th: Difficult to apply LQCD to the low T / high chemical potential region.

Our Contribution JWC, Jian Deng, Lance Labun,1410.5454

• Work out the mapping in a simple model: 1+1dim Gross-Neveu model in the large N limit. Not in the same universality class---different critical exponents but behavior similar.

• More diagrams not included are also important in the power counting: