Search for narrow resonances decaying to dijets in pp collisions at $\sqrt{s}=13~\mathrm{TeV}$ using $12.9~\mathrm{fb}^{-1}$

A search is presented for narrow resonances decaying to dijet final states in proton-proton collisions at $\sqrt{s}=13$ TeV from an integrated luminosity of 12.9 fb$^{-1}$. Results are presented for two searches. A low-mass search, for a resonance mass between 0.6 TeV and 1.6 TeV, is performed using dijets that are reconstructed from calorimeter information in the high-level trigger. A high-mass search, for resonances with mass above 1.6 TeV, is performed using dijets reconstructed with the particle flow algorithm from the normal reconstruction chain. The pseudorapidity separation of the two jets is required to satisfy $|\Delta\eta_{\text{jj}}|<1.3$ with each jet inside the region $|\eta| < 2.5$. The spectra are well described by a smooth parameterization and no significant evidence for new particle production is observed. Upper limits at 95\% confidence level are reported on the production cross section times branching ratio to dijets times acceptance of the $|\Delta\eta_{\text{jj}}|$ and $|\eta|$ cuts for narrow resonances from quark-quark, quark-gluon and gluon-gluon final states. When interpreted in the context of specific models, the limits exclude string resonances with masses below 7.4 TeV, scalar diquarks below 6.9 TeV, axigluons and colorons below 5.5 TeV, excited quarks below 5.4 TeV, color-octet scalars below 3.0TeV, W$^{\prime}$ bosons below 2.7 TeV, Z$^{\prime}$ bosons below 2.1 TeV and between 2.3 to 2.6 TeV, and RS gravitons below 1.9 TeV, extending previously published limits in the dijet channel. $$\textit{This document has been revised with respect to the version dated August 4, 2016.}$$