0000000000270391
AUTHOR
Long Chen
Top-quark pair production at next-to-next-to-leading order QCD in electron positron collisions
We set up a formalism, within the antenna subtraction framework, for computing the production of a massive quark-antiquark pair in electron positron collisions at next-to-next-to-leading order in the coupling $\alpha_s$ of quantum chromodynamics at the differential level. Our formalism applies to the calculation of any infrared-safe observable. We apply this set-up to the production of top-quark top antiquark pairs in the continuum. We compute the production cross section and several distributions. We determine, in particular, the top-quark forward-backward asymmetry at order $\alpha_s^2$. Our result agrees with previous computations of this observable.
The forward-backward asymmetry for massive bottom quarks at the $Z$ peak at next-to-next-to-leading order QCD
We compute the order $\alpha_s^2$ QCD corrections to the $b$-quark forward-backward asymmetry in $e^+e^-\to b{\bar b}$ collisions at the $Z$ boson resonance, taking the non-zero mass of the $b$ quark into account. We determine these corrections with respect to both the $b$-quark axis and the thrust axis definition of the asymmetry. We compute also the distributions of these axes with respect to the electron beam. If one neglects the flavor singlet contributions to the $b$-quark asymmetry, as was done in previous computations for massless $b$ quarks, then the second-order QCD corrections for $m_b\neq 0$ are smaller in magnitude than the corresponding corrections for $m_b=0$. Including the si…
Energy Transfer at the Single-Molecule Level: Synthesis of a Donor-Acceptor Dyad from Perylene and Terrylene Diimides
In 2004, we reported single-pair fluorescence resonance energy transfer (spFRET), based on a perylene diimide (PDI) and terrylene diimide (TDI) dyad (1) that was bridged by a rigid substituted para-terphenyl spacer. Since then, several further single-molecule-level investigations on this specific compound have been performed. Herein, we focus on the synthesis of this dyad and the different approaches that can be employed. An optimized reaction pathway was chosen, considering the solubilities, reactivities, and accessibilities of the building blocks for each individual reaction whilst still using established synthetic techniques, including imidization, Suzuki coupling, and cyclization reacti…