Transverse Momentum Distributions in the Non-Perturbative Region

Understand

We study the low transverse momentum (p_T) distribution of the Z-boson at hadron colliders for p_T ~ Lambda_{QCD} using a factorization and resummation formula derived in the Soft Collinear Effective Theory (SCET).

• In the region p_T ~ Lambda_{QCD}, new non-perturbative effects arise that cannot be entirely captured by the standard parton distribution functions, and require an additional new non-perturbative transverse momentum function (TMF).
• The TMF is field-theoretically defined in SCET, fully gauge invariant, and captures the non-perturbative dynamics that affects the p_T-distribution in the region p_T ~ Lambda_{QCD}.
• The TMF also reduces to the expected perturbative result in the region p_T >> Lambda_{QCD}.