Dibyashree Sengupta (LNF - Frascati)

Challenging SUSY at LHC

While the ATLAS/CMS experiments discovered a Standard Model-like Higgs boson at LHC,no compelling new physics signal has been seen yet. Lack of experimental evidence ofsparticleshas pushed the lower limit on their masses in the multi-TeV regime. LHC searchesfor Weak scale supersymmetry (SUSY) show that gluinos should lie beyond 2.2 TeV and topsquarks should lie beyond 1.1 TeV. Such high mass limits are well beyond early upper limitsfrom naturalness and gives rise to the question whether SUSY is now unnatural. We critiquethe older notions of naturalness and suggest an update based on the more conservativeelectroweak naturalness measure. In that case, SUSY with light higgsinos and highly mixedTeV-scale top squarks is still quite natural. We re-examine higgsino pair production inassociation with a hard QCD jet at the HL-LHC. Another novel signature for natural susymodels is the same-sign diboson (SSdB) +ET/which is a rather clean signal with negligiblysmall SM background. However, such a unique signature can be observed in more thanone well-motivated BSM scenarios, namely: (i) natural SUSY models, (ii) type-III seesawmodel and (iii) type-II seesaw/Georgi-Machacek model. In this talk I present the discoveryprospects of the SSdB +ET/signal that has been analyzed in these BSM models in currentand future runs of the LHC beside providing ways to distinguish among these different BSMmodels. Furthermore, the LHC, being a “top quark factory”, helps in precise measurementof various properties of the top quark. Deviation from the SM prediction in measuring theseproperties of the top quark can, very efficiently, shed light on new physics signal. In thistalk I also present a work in progress where we aim to show how precise measurement ofquantities related to top quark features can indicate towards a new physics signal.