Search for long-lived neutral particles decaying to quark-antiquark pairs in proton-proton collisions at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>8</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>TeV</mml:mi></mml:math>

A search is performed for long-lived massive neutral particles decaying to quark-antiquark pairs. The experimental signature is a distinctive topology of a pair of jets, originating at a secondary vertex. Events were collected with the CMS detector at the CERN LHC in proton-proton collisions at a center-of-mass energy of 8 TeV. The data analyzed correspond to an integrated luminosity of $18.5\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. No significant excess is observed above standard model expectations. Upper limits at 95% confidence level are set on the production cross section of a heavy neutral scalar particle, $H$, in the mass range of 200 to 1000 GeV, decaying promptly into a pair of long-lived neutral $X$ particles in the mass range of 50 to 350 GeV, each in turn decaying into a quark-antiquark pair. For $X$ with mean proper decay lengths of 0.4 to 200 cm, the upper limits are typically $0.5--200\text{ }\text{ }\mathrm{fb}$. The results are also interpreted in the context of an R-parity-violating supersymmetric model with long-lived neutralinos decaying into a quark-antiquark pair and a muon. For pair production of squarks that promptly decay to neutralinos with mean proper decay lengths of $2--40\text{ }\text{ }\mathrm{cm}$, the upper limits on the cross section are typically $0.5--3\text{ }\text{ }\mathrm{fb}$. The above limits are the most stringent on these channels to date.