UCLA Dark Matter 2018

Peiwen Wu (Korea Inst. for Advanced Study): Heavy Quark Flavored Scalar Dark Matter

22 Feb 2018, 11:37

14m

Talk Session 7

Speaker

Peiwen Wu (Korea Institute for Advanced Study (KIAS))

Description

The absence of confirmed signal in dark matter (DM) direct detection (DD) may suggest a weak coupling between DM and the first generation quarks. In this work we consider a real scalar dark matter $S$ which has new Yukawa interactions with charm $c$ and top quark $t$ via a vector-like fermion mediator $\psi$. By setting the Higgs portal to be negligible, we focus on the new Yukawa interactions. Since there is no valence $c,t$ quark in nucleons, DM-gluon scattering at loop level becomes important. We found that renormalization group equation (RGE) effects are crucial in calculating the DM-nucleon scattering rate at ${\mu }_{had}\sim 1\mathrm{G}\mathrm{e}\mathrm{V}$ if one constructs the effective theory at ${\mu }_{EFT}\sim m_Z$. For the perturbative benchmark couplings we choose, combined results from relic abundance requirement $\mathrm{\Omega }{h}^2=0.12$, direct/indirect detection constraints, 13 TeV LHC data have excluded a thermal relic DM with $m_S<m_t/2$ in this model. FCNC processes of top quark can be generated at both tree level $t\to {\psi }^{(\ast )}S\to cSS$ and loop level $t\to c+\gamma /g/Z$, of which the branching fractions are usually below ${10}^{-9}$ after passing the other constraints, which are still safe from the current top quark width measurements.

Presentation materials

PeiwenWu-DM2018.pdf