Measurement of dijet $\mathbf{\textit{k}_{T}}$ in p-Pb collisions at $\mathbf{\sqrt{\textit{s}_{NN}}=5.02}$ TeV

A measurement of dijet correlations in p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV with the ALICE detector is presented. Jets are reconstructed from charged particles measured in the central tracking detectors and neutral energy deposited in the electromagnetic calorimeter. The transverse momentum of the full jet (clustered from charged and neutral constituents) and charged jet (clustered from charged particles only) is corrected event-by-event for the contribution of the underlying event, while corrections for underlying event fluctuations and finite detector resolution are applied on an inclusive basis. A projection of the dijet transverse momentum, $k_{\rm Ty} = p_\rm{T,jet}^\rm{ch+ne} \; \rm{sin}(\Delta\varphi_{\rm{dijet}})$ with $\Delta\varphi_{\rm{dijet}}$ the azimuthal angle between a full and charged jet and $p_\rm{T,jet}^\rm{ch+ne}$ the transverse momentum of the full jet, is used to study nuclear matter effects in p-Pb collisions. This observable is sensitive to the acoplanarity of dijet production and its potential modification in p-Pb collisions with respect to pp collisions. Measurements of the dijet $k_{\rm Ty}$ as a function of the transverse momentum of the full and recoil charged jet, and the event multiplicity are presented. No significant modification of $k_{\rm Ty}$ due to nuclear matter effects in p-Pb collisions with respect to the event multiplicity or a PYTHIA8 reference is observed.

Figures

Figure 1

Dijet |$k_{\rm Ty}$| distributions in p-Pb collisions in the 0-40% V0A multiplicity event class for several kinematic intervals of the full jet (${p_\mathrm{T,jet}^\mathrm{ch+ne}}$). The measurement is compared to PYTHIA8 (tune 4C, $K=0.7$) with and without initial state radiation. The lower panels show the ratio between the measurement and PYTHIA8 including initial state radiation
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Figure 2

Distributions of |$k_{\rm Ty}$| for two V0A event classes (left panel) and three $p_\mathrm{T,assoc\;jet}^\mathrm{ch}$ ranges (right panel)
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Figure 3

Mean of the |$k_{\rm Ty}$| distributions as a function of the full jet transverse momentum ${p_\mathrm{T,jet}^\mathrm{ch+ne}}$ (top) and the associated charged jet transverse momentum $p_\mathrm{T,assoc\;jet}^\mathrm{ch}$ (bottom) compared to PYTHIA8
[png]   [pdf]   [eps]
[png]   [pdf]   [eps]