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A deconfined quantum phase transition (DQPT) provides an extraordinary possibility of the quantum phase transition beyond the Ginzburg-Landau paradigm, which is interwoven with numerous exotic phenomena of the strongly correlated quantum many-body system, e.g., fractional excitation, emergent symmetries, and gauge field. However, various candidates of DQPT have been demonstrated to be weakly first order, and the conformal field theory has to be altered into a nonunitary one. Here we numerically found two linear dispersions with different velocities in one of the few survivors of DQPT---the extended hard-core Bose-Hubbard model on the kagome lattice. Such counterintuitive results directly lead to the negation of possible emergent Lorentz symmetry and the breakdown of conventional theory of DQPT. Furthermore, the snapshots of boson configuration hint that these two velocities may correspond to the dynamics of the fractional excitations and quantum strings, respectively. Our work will inspire researchers to revisit the theory of DQPT and benefit the field of quantum materials and quantum simulations.
Liu et al. (Thu,) studied this question.