Melissa Ratzlaff | Searcharxiv

arXiv2025

A reflexion on the potential evolution of the CLS machine complex : A "Gedanken" experiment

In the next 5 to 10 years, new fourth generation light sources will be coming online either from upgrades or as brand new facilities. The question regarding the competitiveness and the usability of a third generation light source is certainly in the mind of the scientific personnel, which includes both the beamline and the accelerator staff of any third Gen Research Infrastructures. At the Canadian Light Source (CLS), Accelerator Operation and Development (AOD) staff are responsible for the daily operation of the machines, their upgrades which extend to long term development and shall also raise awareness on their possibilities. The boundaries of this mind experiment are 1) we must use CLS infrastructure, 2) identify the existence of the knowledge to realize an idea, 3) the realization, with whom, how, with which funds and under which administrative supervision is out of bounds.

physics.acc-ph↗

arXiv2016

Heavy Higgs decay to $t\bar{t} Z$ and constraints on a $750$ GeV pseudoscalar

In models with multiple nondegenerate Higgs bosons, the decay chain $H/A \to A/H Z\to t\bar{t} Z$ may have a partial width comparable to the $t\bar{t}$ decay mode. We recast the ATLAS standard model $t\bar{t} Z$ measurement to put limits on the rate for this process. Limits are also set on the two Higgs doublet model at low $\tan β$ that are sensitive to a heavy Higgs mass as high as $\sim 750$ GeV. We then discuss the $750$ GeV diphoton excess in terms of a pseudoscalar that also has the decays $A\to HZ$ and $A\to H^\pm W^\mp$. These decays strongly constrain the partial widths for $A\toγγ$ and $A\to gg$ when combined with the $t\bar t$ resonance search limits. In a benchmark model the mass of $H$ should be close to 650 GeV.

hep-ph↗