Very forward inclusive jet cross sections in p+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02~\mathrm{TeV}$

Measurements of very forward inclusive jet energy spectra with the CMS experiment at the LHC are presented. The data were collected with the CASTOR calorimeter in the pseudorapidity range $-6.6<\eta<-5.2$ in proton lead collisions, with a centre-of-mass energy of $\sqrt{s_{NN}}=5.02~\mathrm{TeV}$ in 2013. The analysed data samples correspond to integrated luminosities of 3.13 and $6.71~\mathrm{nb}^{-1}$, for beam configurations with the proton (p+Pb) or ion (Pb+p) towards CASTOR, respectively. The results are presented for energy ranges from 600 to 2500 (p+Pb) and 4000 $\mathrm{(Pb+p)~GeV}$. The spectra are unfolded to the particle level and compared to predictions of various event generators. In addition, the p+Pb/Pb+p ratio of the spectra is presented, for which the systematic uncertainties in the measurement are significantly reduced. None of the event generators under consideration describe all spectra in their full energy range, and deviations between data and models of more than two orders of magnitude are observed.