Quark and Gluon Momentum Fractions in the Pion from Nf=2 +1 +1 Lattice QCD

We perform the first full decomposition of the pion momentum into its gluon and quark contributions. We employ an ensemble generated by the Extended Twisted Mass Collaboration with N_f=2 +1 +1 Wilson twisted mass clover fermions at maximal twist tuned to reproduce the physical pion mass. We present our results in the MS ¯ scheme at 2 GeV. We find ⟨x ⟩_{u +d}=0.601 (28 ) , ⟨x ⟩_s=0.059 (13 ), ⟨x ⟩_c=0.019 (05 ), and ⟨x ⟩_g=0.52 (11 ) for the separate contributions, respectively, whose sum saturates the momentum sum rule.