Search for stopped long-lived particles produced in pp collisions at $\sqrt{s}=13~\mathrm{TeV}$

A search is presented for long-lived particles that lose sufficient kinetic energy and come to rest in the CMS detector. If such a particle decays to at least one standard model particle, it would produce a spectacular signature: a high-energy jet that is not coincident with the proton-proton collisions. During the time intervals without collisions, the detector is quiet and only rare background processes must be considered. The 2015 search is performed using a $2.7~\mathrm{fb}^{-1}$ sample of pp collision run data at $\sqrt{s}=13~\mathrm{TeV}$, corresponding to 135 hours of trigger livetime, while the 2016 search is carried out using a $36.8~\mathrm{fb}^{-1}$ sample of pp collision run data at the same energy, which corresponds to 586 hours of trigger livetime. Four events are observed in the 2015 analysis and thirteen events are observed in the 2016 analysis; both observed numbers of events are consistent with the predicted backgrounds. Limits are placed on the mass of gluinos and stop quarks with lifetimes spanning 13 orders of magnitude. Assuming a cloud model of R-hadron interactions, and combining the results from the 2015 and 2016 analyses, for $E_{\mathrm{g}} > 130~\mathrm{GeV}$ and $BR(\tilde{g} \rightarrow g\tilde{\chi}^0) = 100\%$, gluinos with lifetimes from $10~\mu\mathrm{s}$ to $1000~\mathrm{s}$ and $m_{\tilde{g}} < 1385~\mathrm{GeV}$ are excluded. Under a similar assumption, $E_{\mathrm{t}} > 170~\mathrm{GeV}$ and $BR(\tilde{t} \rightarrow t\tilde{\chi}^0) = 100\%$, we are able to exclude long-lived stop quarks with lifetimes from $10~\mu\mathrm{s}$ to $1000~\mathrm{s}$ and $m_{\tilde{t}} < 744~\mathrm{GeV}$. These are the strongest limits on stopped long-lived particles to date.