2022/04/06 by Kaustubh Agashe, Sagar Airen, Agashe, Kaustubh +7
Computer Science · Medicine · Physics and Astronomy · #Distributed and Parallel Computing Systems #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph) #Medical Imaging Techniques and Applications #Particle physics theoretical and experimental studies
paper · pdf · doi:10.48550/arxiv.2204.02928
openalex publication_date 2022/04/06 · openalex created_date 2022/05/05 · openalex updated_date 2026/07/28
We first review the decade-old, broad collider physics research program dubbed energy-peaks. We consider the energy distribution of a massless particle in the lab frame arising from the two-body decay of a heavy particle produced unpolarized, whose boost distribution is arbitrary. Remarkably, the location of the peak of this child particle's energy distribution is identical to its single-valued energy in the rest frame of the parent, which is a function of the parent's mass and that of the other decay product. We summarize generalizations to other types of decay and a variety of applications to BSM. The energy-peak idea can also furnish a measurement of the top quark via the energy of the bottom quark from its decay, which, based on the "parent-boost-invariance," is less sensitive to details of the production mechanism of the top quark (cf.~most other methods assume purely SM production of the top quarks, hence are subject to uncertainties therein, including a possible BSM contribution). The original proposal along this line was to simply use the b-jet energy as a very good approximation to the bottom quark energy. This method has been successfully implemented by the CMS collaboration. However, the b-jet energy-peak method is afflicted by the jet-energy scale (JES) uncertainty. Fortunately, this drawback can be circumvented by using the decay length of a B-hadron contained in the b-jet as a proxy for the bottom quark energy. An interesting proposal is to then appropriately dovetail the above two ideas resulting in a "best of both worlds" determination of the top quark mass, i.e., based on a measurement of the B-hadron decay length, but improved by the energy-peak concept: this would be free of JES uncertainty and largely independent of the top quark production model. We summarize here the results of such an analysis which is to appear in a forthcoming paper.