Slepton pair production at next-to-leading power

TL;DR

This paper develops and applies next-to-leading power (NLP) threshold resummation to slepton-pair production in hadronic collisions, extending beyond the conventional leading-power (LP) approach. It derives NLP leading-logarithmic (LL) contributions for both $q\bar{q}$ and $qg$ initial states, and provides a practical framework for matching NLP resummed results to fixed-order NLO predictions using Mellin-space techniques and the Minimal Prescription. The authors demonstrate that NLP LL terms can be as large as LP next-to-leading logarithms, significantly affect scale uncertainties, and remain relevant at high slepton masses, with explicit results for LHC energies and a future FCC-hh scenario at $\sqrt{s}=85$ TeV. The study concludes that neglecting NLP contributions may underestimate the missing higher-order uncertainties and that NLP-resummed predictions should be incorporated into precision BSM cross-section calculations, including for heavy sleptons where PDF uncertainties are substantial. Overall, the work provides analytic NLP results, detailed numerical implementations, and critical comparisons with existing tools (e.g., Resummino) to refine theoretical predictions for slepton searches and potential discoveries.

Abstract

Near threshold, cross sections for the production of heavy particles are sensitive to large logarithmic terms, which must be resummed to all orders in perturbation theory. Current state-of-the art calculations for inclusive slepton pair production at hadron colliders has focused on higher-order logarithms in the leading power of the threshold variable. Here, we evaluate the next-to-leading power contribution in the threshold variable to leading logarithmic accuracy. We find that the next-to-leading power contributions can be significant compared to the next-to-leading logarithmic terms at leading power, and that existing calculations underestimate the scale error for large slepton masses. We include results for a potential future FCC-hh machine at $\sqrt{s}=85$ TeV.

Figures (20)

• Figure 1: Partonic tree-level diagram for the production of the slepton pair $\tilde{\ell}^k_{A}\tilde{\ell}'^{*k}_{B}$; $V$ can be a photon, $Z$ or $W^\pm$ depending on the final state.
• Figure 2: $\mathcal{O}\left({\alpha_s}\right)$ loop corrections to the quark--vector-boson vertex. Left: Virtual gluon exchange. Right: Gluino--squark loop contribution. $C$ and $D$ denote the squark mass eigenstates.
• Figure 3: Real-emission diagrams that contribute to $\mathcal{O}\left({\alpha_s}\right)$, for the different initial states that contribute to this order. The diagram for the $\overline{q}_ig$ initial state is obtained by simply reversing the fermion arrow in the $q_ig$ diagram.
• Figure 4: $\mathcal{O}\left({\alpha_s}\right)$ contributions to the quark (of flavor $i$) self-energy. As in Figure \ref{['fig:virtual']} there is an additional sum over the squark mass eigenstate $C$.
• Figure 5: Total cross-sections for smuon pair-production as a function of the smuon mass, at $\sqrt{s}=13.6$ TeV. Shown are both scale and combined PDF and $\alpha_s$ errors.