Constraints on charm-anticharm asymmetry in the nucleon from lattice QCD

• Main Authors: Raza Sabbir Sufian, Tianbo Liu, Andrei Alexandru, Stanley J. Brodsky, Guy F. de Téramond, Hans Günter Dosch, Terrence Draper, Keh-Fei Liu, Yi-Bo Yang
• Format: Article
• Language: English
• Published: Elsevier 2020-09-01
• Series: Physics Letters B
• Subjects: Intrinsic charm; Form factor; Parton distributions; Lattice QCD; Light-front holographic QCD
• Online Access: http://www.sciencedirect.com/science/article/pii/S0370269320304366

We present the first lattice QCD calculation of the charm quark contribution to the nucleon electromagnetic form factors GE,Mc(Q2) in the momentum transfer range 0≤Q2≤1.4 GeV2. The quark mass dependence, finite lattice spacing and volume corrections are taken into account simultaneously based on the calculation on three gauge ensembles including one at the physical pion mass. The nonzero value of the charm magnetic moment μMc=−0.00127(38)stat(5)sys, as well as the Pauli form factor, reflects a nontrivial role of the charm sea in the nucleon spin structure. The nonzero GEc(Q2) indicates the existence of a nonvanishing asymmetric charm-anticharm sea in the nucleon. Performing a nonperturbative analysis based on holographic QCD and the generalized Veneziano model, we study the constraints on the [c(x)−c¯(x)] distribution from the lattice QCD results presented here. Our results provide complementary information and motivation for more detailed studies of physical observables that are sensitive to intrinsic charm and for future global analyses of parton distributions including asymmetric charm-anticharm distribution.