LAUSR

We consider a twin Higgs model where the ${Z}_{2}$ twin symmetry is broken spontaneously, not explicitly. We show that introducing an exact copy of the standard model with a renormalizable Higgs portal potential is enough to realize such a scenario. In this scenario, the $SU(4)$ breaking scale $f$ is determined by the scale where the Higgs self-quartic coupling flips its sign, whose standard model prediction is $\mathcal{O}({10}^{10}\text{ }\text{ }\mathrm{GeV})$. For the misalignment of nonzero vacuum expectation values of the twin Higgs fields, it is explicitly shown that parameter tuning of $\mathcal{O}({m}_{h}^{2}/{f}^{2})$ is required, so we conclude that minimal setup does not solve the hierarchy problem. We point out that the tuning can be significantly reduced ($f\ensuremath{\sim}2.7\text{ }\text{ }\mathrm{TeV}$) if there are twin vectorlike leptons with a large Yukawa coupling.