Abstract
The COMPASS collaboration published precise data on production cross section of charged hadrons in lepton-hadron semi-inclusive deep inelastic scattering, showing almost an order of magnitude larger than next-to-leading order QCD calculations when ${P}_{{h}_{T}}$ and ${z}_{h}$ are sufficiently large. We explore the role of power corrections to the theoretical calculations, and quantitatively demonstrate that the power corrections are extremely important for these data when the final-state multiplicity is low and the production kinematics is near the edge of phase space. Our finding motivates more detailed studies on power corrections for upcoming experiments at Jefferson Lab, as well as the future Electron-Ion Collider.
Highlights
Unveiling the structure of nucleons in terms of quarks and gluons of quantum chromodynamics (QCD) is one of the central goals that has been actively pursued by the science community since the first lepton-proton deep inelastic scattering (DIS) experiment took place at SLAC about 50 years ago [1]
Since the purpose of this paper is to show the relevance and potential impact of next-to-leading power (NLP) contributions to warrant a urgent and more detailed study of the NLP power corrections to the low multiplicity observables in semi-inclusive DIS (SIDIS), instead of a precise fitting to the data, we perform straightforward leading order calculations in power of αs for both leading power (LP) and NLP contributions to the differential multiplicity defined in Eq (41)
SUMMARY AND CONCLUSIONS We have presented the first calculations of power corrections to charged meson productions in SIDIS at large transverse momentum, PhT ∼ Q ≫ ΛQCD, in terms of the QCD collinear factorization formalism
Summary
Unveiling the structure of nucleons (or hadrons, in general) in terms of quarks and gluons of quantum chromodynamics (QCD) is one of the central goals that has been actively pursued by the science community since the first lepton-proton deep inelastic scattering (DIS) experiment took place at SLAC about 50 years ago [1]. In the frame where the exchange virtual gauge boson of momentum q and the colliding hadron of momentum P are headed on, the leading contribution to the SIDIS is naturally from the region where the transverse momentum of the observed hadron, PhT ≪ Q, and the scattering provides a short-distance probe with two very different momentum scales, from which the harder scale Q localizes the hard collision to “see” the particle nature of quarks and gluons, while the soft scale PhT is sensitive to the confined motion of quarks and gluons in the direction perpendicular to the direction of the colliding proton In this kinematic regime where Q2 ≫ P2hT ≳ 1=fm, similar to the inclusive DIS, SIDIS cross section can be factorized into a product of perturbatively calculable lepton-parton scattering at the hard scale Q, corresponding transverse momentum dependent (TMD) parton distribution functions (or TMDs), φi=Pðx; kT; μ2Þ with kT being the active parton’s transverse momentum perpendicular to the direction of the colliding hadron of momentum P, and TMD fragmentation functions (FFs), Dj→hðz; pT; μ2Þ with the emergent hadrontype h carrying momentum fraction between z and z þ dz of the fragmenting parton of momentum p and pT being the parton’s transverse momentum off the direction of the observed final-state hadron of momentum Ph, where i; j 1⁄4 fq; q; gg represent the active parton flavors [9,10].
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