SLIDE 1
: A QCD AXION DIRECT- DETECTION EXPERIMENT
XIAOYUE LI FOR THE MADMAX COLLABORATION MAX PLANCK INSTITUTE FOR PHYSICS, MUNICH, GERMANY
TAUP Toyama, September 9, 2019
Xiaoyue Li (MPP Munich) TAUP 2019 Toyama 09.09.2019
INTRODUCTION
THE STRONG CP PROBLEM
▸ The QCD Lagrangian contains a CP-violating term: ▸ Neutron electric dipole moment ▸ The Standard Model does not provide a reason for why is so
tiny, i.e. the strong CP problem.
▸ The Peccei-Quinn mechanism provides a reason for the value of
and predicts a light neutral pseudoscalar boson — the axion.
2
ℒQCD = . . . + αs 8π ¯ θ Gμνa ˜ Gμν
a ,
¯ θ = θQCD + θYukawa ∈ [−π, π] ∼ 𝒫(1) dN ∼ 10−16 ¯ θ e-cm < 3 × 10−26 e-cm ⇒ ¯ θ < 3 × 10−10
¯ θ ¯ θ