Transverse-Momentum Resummation for Gauge Boson Pair Production at the Hadron Collider

TL;DR

This work develops NNLL transverse-momentum resummation for gauge-boson pair production (W^+W^-, ZZ, and the first NNLL treatment of WZ) at the LHC using soft-collinear effective theory. The formalism factorizes the q_T spectrum into a hard function, TMD-like PDFs with a collinear anomaly, and RG evolution, and it is matched to NLO fixed-order results to include non-singular contributions. Numerical results show reduced scale dependence and modest non-perturbative effects, with predictions that agree with CMS ZZ 8 TeV data and quantified PDF uncertainties. The study enhances SM predictions for gauge-boson kinematics and provides robust backgrounds for Higgs and new-physics searches at current and future hadron colliders.

Abstract

We perform the transverse-momentum resummation for $W^{+}W^{-}$, $ZZ$, and $W^{\pm}Z$ pair productions at the next-to-next-to-leading logarithmic accuracy using soft-collinear effective theory for $\sqrt{S}=8 \text{TeV}$ and $\sqrt{S}=14 \text{TeV}$ at the LHC, respectively. Especially, this is the first calculation of $W^{\pm}Z$ transverse-momentum resummation. We also include the non-perturbative effects and discussions on the PDF uncertainties. Comparing with the next-to-leading logarithmic results, the next-to-next-to-leading logarithmic resummation can reduce the dependence of the transverse-momentum distribution on the factorization scales significantly. Finally, we find that our numerical results are consistent with data measured by CMS collaboration for the $ZZ$ production, which have been only reported by the LHC experiments for the unfolded transverse-momentum distribution of the gauge boson pair production so far, within theoretical and experimental uncertainties.

Figures (6)

• Figure 1: Comparison of the leading singular (red) and the exact NLO (black) distributions in the small $q_T$ region.
• Figure 2: The non-perturbative effects on the differential cross sections of gauge boson pair production with $\sqrt{S}=14~\text{TeV}$, respectively.
• Figure 3: Up: the $q_T$ distributions with scale uncertainties for gauge boson pair productions at the LHC with $\sqrt{S}=8~\text{TeV}$ and $\sqrt{S}=14~\text{TeV}$. Down: NNLL + NLO results normalized to NLO.
• Figure 4: The PDF uncertainties of NNLL order resummed transverse-momentum for gauge boson pair production, where the bands represent 2$\sigma$ deviation.
• Figure 5: Comparison of NNLL + NLO resummed $q_T$ distribution for $W^+W^-$ and $ZZ$ distributions in the SCET and CSS frame at $\sqrt{S}=14~\text{TeV}$ with MRST2002NLO PDF set.