Search for low mass vector resonances decaying into quark-antiquark pairs with $77.0~\mathrm{fb}^{-1}$ of proton-proton collisions at $\sqrt{s}=13~\mathrm{TeV}$

A search for low mass vector resonances decaying into quark-antiquark pairs is presented. The analysis is based on data collected in proton-proton collisions in 2017 and combined with data collected in 2016 at $\sqrt{s}=13~\mathrm{TeV}$ with the CMS detector at the CERN LHC, corresponding to a total integrated luminosity of $77.0~\mathrm{fb}^{-1}$. Resonance candidates are identified as large-radius jets with two pronged substructure at high transverse momentum. The jet invariant mass spectrum is probed for a potential peak over a smoothly falling background. No evidence for such a resonance is observed within the mass range of $50-450~\mathrm{GeV}$. Upper limits at the $95\%$ confidence level are set on the mass-coupling parameter space. The 2017 results extend the search region for the first time to masses between $300~\mathrm{GeV}$ and $450~\mathrm{GeV}$ in the boosted regime.