Dijet invariant mass of charged-particle jets in pp and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

Abstract

The ALICE collaboration presents the first measurement of the dijet invariant mass spectra of charged-particle jets in pp and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. Charged particles in the mid-pseudorapidity region, $|\eta |<0.9$, are clustered into jets using the anti-$k_{\mathrm{T}}$ algorithm with a resolution parameter $R=0.4$. The leading and subleading jets are required to have a transverse momentum $p_{\mathrm{T}}>20$ GeV$/c$ and to be contained within $\left|{\eta }_{\mathrm{jet}}\right|<0.5$. The dijet invariant mass spectrum and the nuclear modification factor $R_{\mathrm{pA}}$ are presented in the low-mass region of 75 to 150 GeV/$c^2$. The nuclear modification factor for charged-particle dijet invariant mass is consistent with unity. This is in line with previous small-system jet studies. Comparisons with Monte Carlo simulations suggest that the low-mass region is sensitive to anti-shadowing effects on parton densities in the nucleus, however, the expected signal is subtle and below the present experimental sensitivity.

21 pages, 2 captioned figures, authors from page 16, submitted to EPJC, figures at http://alice-publications.web.cern.ch/node/13214