The qT and $$ \Delta {\phi}_{t\overline{t}} $$ spectra in top-antitop hadroproduction at NNLL+NNLO: the interplay of soft-collinear resummation and Coulomb singularities
Bibliographic record
Abstract
A bstract In this paper, we present the resummation-improved differential transverse momentum and azimuthal decorrelation cross sections, $$ {\textrm{d}\sigma}_{t\overline{t}}/{\textrm{d}q}_{\textrm{T}} $$ d σ t t ¯ / d q T and $$ {\textrm{d}\sigma}_{t\overline{t}}/\textrm{d}\Delta {\phi}_{t\overline{t}} $$ d σ t t ¯ / d ∆ ϕ t t ¯ , in top-antitop pair production at the LHC. Our calculation is based on the observation that both cross sections are dominated by topologies where the top-quark pair is well separated, expressed in their relative velocity $$ {\beta}_{t\overline{t}}\sim \mathcal{O}(1) $$ β t t ¯ ∼ O 1 , at colliding energies of $$ \sqrt{s} $$ s = 13 TeV or higher. Therefore, the asymptotic behaviour in the limits q T → 0 and $$ \Delta {\phi}_{t\overline{t}} $$ ∆ ϕ t t ¯ → 0 can mostly be captured by the soft and collinear resummation in the HQET+SCET framework. Nevertheless, starting at N 2 LL, Coulomb singularities emerge in the threshold regime, $$ {\beta}_{t\overline{t}} $$ β t t ¯ → 0, in both the hard sector and its evolution kernels, leading to unphysical results upon integration over the entire $$ {\beta}_{t\overline{t}} $$ β t t ¯ range. To this end, two prescriptions, dubbed the D- and R-prescription, are introduced to regularise these Coulomb singularities. They embody two fundamentally different methods to truncate the threshold enhanced terms, rendering their contribution finite. In the absence of a combined threshold and small-transverse-momentum resummation, we present a quantitative assessment of the ambiguity introduced by the choice of prescription, itself a test of the sensitivity of our calculation to such threshold enhancements, for both the $$ {\textrm{d}\sigma}_{t\overline{t}}/{\textrm{d}q}_{\textrm{T}} $$ d σ t t ¯ / d q T
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.004 | 0.003 |
| Science and technology studies | 0.002 | 0.003 |
| Scholarly communication | 0.004 | 0.003 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.017 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".