leptophilic dark matter & the magnetic moment of the muon

Leptophilic Dark Matter &The Magnetic Moment of the Muon

with Zackaria Chacko& Prateek Agrawalhep-ph:1402.7369

May 6 2014

Dark Matter

Characteristics still unknown

Leptophilic Bounds

• Tree level scattering through renormalizable couplings with leptons only

Hadron ColliderElectrons are light

Fewer photons

LeptophilicDM

• Charged mediator carries flavor

Anomalous Magnetic Momentof the Muon

• Or,

•

• (Exp)(Thy)

𝑎𝜇 : A Probe of New Physics• agrees with experiment to

• New Physics contribution if only lepton mass breaks chirality

• is times more sensitive to new physics than • Naively sets a scale for physics that removes

the anomaly, ~150 GeV

ExperimentBrookhaven Fermilab J-PARC

E821 E989E34

Experiments expect to reduce uncertainty by a factor of 4

Charged Mediators• Categorize by spin of the DM

– Use the notation

– As well as and• Example: Spin 0 DM

Neutral Mediators

• Spin 0:

• Spin 1:

Comparison Bounds

• LEP– Monophoton

• Fermionic DM only– Compositeness

• Neutral Mediators Only

• Direct Detection– LUX– Effective Operator

Analysis

Scalar DM Results

• 2 σ blue band

Only for Complex Scalar

• For λ~1 the scale is ~100 GeV• Expect LEP bounds to disfavor entire band

• Purple:600 Gev• Green: 400 GeV• Black: 250 GeV

Scalar DM with Neutral Mediator

Only for Complex Scalar

• For λ~1 the scale is ~100 GeV in unexcluded region

Fermionic DM• Charged Vector Mediator

• Neutral Vector Mediator

Dirac

MajoranaDirac Only

• For λ~1 scale is ~ 100 GeV

Conclusions

• Leptophilic DM has potential to solve the anomaly

• Charged mediator models that preserve chiral symmetry require mediator masses less than a few hundred GeV for ~1 couplings

• A few windows aside, these models are tightly constrained by experiment

• Viable Leptophilic Wimps may require chiral symmetry breaking interactions

Extras

Direct Detection Bounds

• Use LUX bounds and effective operators

LEP Bounds• Assume universal

coupling to leptons• P. J. Fox, R. Harnik, J. Kopp,Y. Tsai,

Phys. Rev. D 84, 014028 (2011)

• Only Fermionic DM for monophoton (so far)

• Compositeness bounds for neutral mediators

Indirect Detection• Y. Bai and J. Berger hep-ph/1402.6696

Relic Abundance• Y. Bai and J. Berger hep-ph/1402.6696

g-2 Theory QED

4-loop calculation & 5-loop estimationWeak

2-loopHadronic Vacuum polarization

Kind of. (Optical Theorem) Dominates error

Hadronic Light by Light Error Runner up

X

Direct Detection• DM couples to atomic electrons• Momentum transfer from DM is tiny

– –

• J. Kopp, V. Niro, T. Schwetz, and J. Zupan, Phys. Rev. D 80, 083502 (2009)

Direct Detection Operators

• Real Scalar: None• Complex Scalar:• Majorana Fermion:None• Dirac Fermion:

• Real Vector: None

LEP Compositeness

• Only neutral mediator models bounded