Topological susceptibility of QCD with dynamical Möbius domain-wall fermions

We compute the topological susceptibility ${\chi }_t$ of lattice QCD with $2+1$ dynamical quark flavors described by the Möbius domain-wall fermion. Violation of chiral symmetry as measured by the residual mass is kept at $\sim$1 MeV or smaller. We measure the fluctuation of the topological charge density in a "slab" sub-volume of the simulated lattice using the method proposed by W. Bietenholz, P. de Forcrand, and U. Gerber, J. High Energy Phys. 12, 070 (2015) and W. Bietenholz, K. Cichy, P. de Forcrand, A. Dromard, and U. Gerber, PoS LATTICE 2016, 321 (2016). The quark mass dependence of ${\chi }_t$ is consistent with the prediction of chiral perturbation theory, from which the chiral condensate is extracted as ${\Sigma }^{\overline{MS}}\left(\text{2 GeV}\right)=\left[274\right(13\left)\right(29)\text{MeV}{]}^3$, where the first error is statistical and the second one is systematic. Combining the results for the pion mass $M_{\pi }$ and decay constant $F_{\pi }$, we obtain ${\chi }_t=0.229\left(03\right)\left(13\right)M_{\pi }^2{F}_{\pi }^2$ at the physical point.