Phenomenology of long-lived particles and portals to new physics

Concrete results of my project for each of these three classes or new physics “portals” include:

i) the development of optimal searches at colliders (such as the Large Hadron Collider) and other experiments (such as the Super-Kamiokande neutrino detector) for models predicting long-lived heavy neutral leptons. This research contributed to the following articles:

• Displaced heavy neutrinos from Z’ decays at the LHC, C.-W. Chiang, G. Cottin, A. Das and S. Mandal, JHEP 070, 1912 (2019)

• Searching for light long-lived neutralinos at Super-Kamiokande, P. Candia, G. Cottin, A. Méndez, V. Muñoz, Phys.Rev.D 104, 055024 (2021) 

• Heavy neutral leptons in effective field theory and the high-luminosity LHC, G. Cottin, J. C. Helo, M. Hirsch, A. Titov and Z. S. Wang, JHEP 09, 039 (2021)

• Long-lived heavy neutral leptons at the LHC: four-fermion single-N_R operators, R. Beltrán, G. Cottin, J. C. Helo, M. Hirsch, A. Titov and Z. S. Wang, JHEP 01, 044 (2022)

ii) concrete constraints from disappearing charged track searches at the LHC and at a future 100 TeV collider on a dark matter model with new electroweak multiplets. This research contributed to the following article:

• Collider Probes of Real Triplet Scalar Dark Matter, C.-W. Chiang, G. Cottin, Y. Du, K. Fuyuto and M.J. Ramsey-Musolf, JHEP 01, 198 (2021)

iii) definition of concrete regions in parameter space of models predicting long-lived charged scalars, as well as provide a discriminating strategy that can be used in the search for neutral and doubly charged Higgs bosons. This research contributed to the following articles:

• Long-lived charged particles and multi-lepton signatures from neutrino mass models,  C. Arbeláez, G. Cottin, J. C. Helo and M. Hirsch, Phys. Rev. D 101, 095033 (2020)

• Boosted W/Z Tagging with Jet Charge and Deep Learning, Y.-C. J. Chen, C.-W. Chiang, G. Cottin and D. Shih, Phys. Rev. D 101, 053001 (2020)

In addition, I contributed as editor and author in the Long-Lived Particle Community whitepaper, which took several years of work before publication, which materialized during this FONDECYT grant:

• Searches for long-lived particles beyond the Standard Model at the Large Hadron Collider, J. Alimena, J. Beacham, M. Borsato, Y. Cheng, X. C. Vidal, G. Cottin, et al., Journal of Physics G 47, 090501 (2020)