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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)
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Neutrino and Dark Matter are Portals to New Physics
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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!
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5
How neutrino magnetic moment arises in SM?
ii jj
ll
WW
ii jj
ll
WW
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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!
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Dark Matter (DM)
• Bigger density than the visible Universe• Its existence hints that there might be a dark
sector
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Portals to the Dark Sector
• Other dark matter candidates include MACHOs: MAssive Compact Halo Objects WIMPs: Weakly Interacting Massive Particles
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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)
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Neutrino Atomic Ionization
• The complete set of neutrino electromagnetic form factor is can be constrained:
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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)!
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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
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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
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Toy: ν-H atomic ionization, exact result obtained (1307.2857)
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Toy: ν-H atomic ionization, exact result obtained (1307.2857)
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Two Approximations
Free Electron Approx.
(revisited by Voloshin et.al)Equivalent Photon Approx.
binding momentum of hydrogen: αme↓
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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
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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
↓ ↓
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Benchmark: Ge Photoionization
Exp. data: Ge solid
Theory: Ge atom (gas)
Above 100 eV error under 5%.
JWC et. al. arXiv: 1311.5294
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Ge atomic ionization withab initio MCRRPA Theory
JWC et. al. arXiv: 1311.5294
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Ge atomic ionization withab initio MCRRPA Theory
JWC et. al. arXiv: 1311.5294
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Ge atomic ionization withab initio MCRRPA Theory
JWC et. al. 1411.0574
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JWC et. al. arXiv: 1411.0574
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Direct Dark Matter Detection
RPP 2014
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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)
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Electron Recoil Background for DARWIN (Lxe)
L. Baudis et al 1309.7024
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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
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Searching for the QCD Critical End Point
Jiunn-Wei Chen
National Taiwan U.
JWC, Jian Deng, Lance Labun
1410.5454
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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)
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4th momentCPOD 2014
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3rd momentCPOD 2014
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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
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From the hottest to the coolest, and back?
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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
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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
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Solar Neutrino Flux
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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
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scattering
ee
eνeν Xe
Weak InteractionWeak Interaction Magnetic momentMagnetic moment
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How low is low enough?Be
1010•
Now sub-keV Ge detector is available!
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Parton Physics on a Euclidean LatticeX. Ji, PRL, 2013
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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.
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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: