Speaker
Description
In this work, the spectra for the observables, $q_{\mathrm{T}}^{\mathrm{out}}=\left| \vec{q}_{t\bar{t}}\cdot \Big(\frac{\vec{p}_{t}}{|\vec{p}_{t}|}\times\vec{n}\Big) \right|$ and $q_{\mathrm{T}}^{\mathrm{in}}=\sqrt{q_{\mathrm{T}}^2-(q_{\mathrm{T}}^{\mathrm{out}})^2}$, are investigated for the process $pp\to t\bar{t}X$. Here $\vec{p}_t$ stands for the spatial momentum of the top quark and $\vec{n}$ represents one of the beam directions. In analogy to the inclusive $q_{\mathrm{T}}$ distribution, the $q_{\mathrm{T}}^{ \mathrm{out}}$ and $q_{\mathrm{T}}^{\mathrm{in}}$ spectra in their respective asymptotic regimes are also governed by the soft and collinear radiations about the beam, which can therefore incite poor convergence in the outcomes from the perturbative calculation. To improve this, we carry out the resummation on those soft/collinear fluctuations with the aid of the SCET-based (rapidity) renormalisation groups. To validate, we compare the outputs from the fixed-order calculation with those from SCET, and observe the agreement in both NLO and N$^2$LO in the limit $q_{\mathrm{T}}^{ \mathrm{out/in}}\to 0$ GeV. As to the resummed distributions, the results up to N$^2$LL precision have been evaluated and in comparison to NLL, the manifest decline in the uncertainty has been found out amongst the N$^2$LL curves.
| Submitted on behalf of a Collaboration? | No |
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