3 research outputs found
Top polarisation studies in and production
The polarisation of top quarks produced in high energy processes can be a
very sensitive probe of physics beyond the Standard Model. The kinematical
distributions of the decay products of the top quark can provide clean
information on the polarisation of the produced top and thus can probe new
physics effects in the top quark sector. We study some of the recently proposed
polarisation observables involving the decay products of the top quark in the
context of and production. We show that the effect of the top
polarisation on the decay lepton azimuthal angle distribution, studied recently
for these processes at leading order in QCD, is robust with respect to the
inclusion of next-to-leading order and parton shower corrections. We also
consider the leptonic polar angle, as well as recently proposed energy-related
distributions of the top decay products. We construct asymmetry parameters from
these observables, which can be used to distinguish the new physics signal from
the background and discriminate between different values of
and in a general type II two-Higgs doublet model. Finally, we show
that similar observables may be useful in separating a Standard Model
signal from the much larger QCD induced top pair production background.Comment: 33 pages, 35 figures, references adde
The Vincia Parton Shower
We summarize recent developments in the VINCIA parton shower. After a brief
review of the basics of the formalism, the extension of VINCIA to hadron
collisions is sketched. We then turn to improvements of the efficiency of
tree-level matching by making the shower history unique and by incorporating
identified helicities. We conclude with an overview of matching to one-loop
matrix elements.Comment: 6 pages, to appear in the proceedings of DIS 201
Pre-clinical experience of an adaptive plan library strategy in radiotherapy of rectal cancer: An inter-observer study
Background and purpose: The clinical target volume (CTV) in radiotherapy of rectal cancer is subject to large deformations. With a plan library strategy, the treatment may be adapted to these deformations. The purpose of this study was to determine feasibility and consistency in plan selection for a plan library strategy in radiotherapy of rectal cancer. Material and methods: Thirty rectal cancer patients were included in this retrospective study with in total 150 CBCT scans. A library of CTVs was constructed with in-house built software using population statistics on daily rectal deformations. The library consisted of five plans based on: the original CTV, two larger, and two smaller CTVs. An inter-observer study (study-I) was performed to test the consistency in plan choices between four observers (all RTTs). After five months the observers were asked to re-evaluate (study-II) the same set of scans based on refined guidelines. Results: In study-I the observers reached accordance with the majority choice in 69% of cases. This improved to 87% in study-II. The consensus meeting revealed that inconsistency in choices mainly arose from inadequate instructions, which were later clarified and formulated more accurately. Conclusion: Plan selection based on daily CBCT scans for rectal cancer patients is feasible, and can be performed consistently by well-trained RTTs. Keywords: Plan library, Rectum, Adaptive radiotherapy, Inter-observer stud