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Search: authors:"Mihailo Backović"

12 papers found.
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LHC vector resonance searches in the \( t\overline{t}Z \) final state

LHC searches for BSM resonances in l + l − , jj, \( t\overline{t} \) , γγ and VV final states have so far not resulted in discovery of new physics. Current results set lower limits on mass scales of new physics resonances well into the \( \mathcal{O}(1) \) TeV range, assuming that the new resonance decays dominantly to a pair of Standard Model particles. While the SM pair...

Di-photon excess illuminates dark matter

We propose a simplified model of dark matter with a scalar mediator to accommodate the di-photon excess recently observed by the ATLAS and CMS collaborations. Decays of the resonance into dark matter can easily account for a relatively large width of the scalar resonance, while the magnitude of the total width combined with the constraint on dark matter relic density leads to...

Search strategies for TeV scale fermionic top partners with charge 2/3

Searches for fermionic top partners at the TeV scale will bring forward a new final state kinematic regime and event topologies, where Run I search strategies will inevitably fail. We propose concrete search strategies for singly produced charge 2/3 fermionic top partners (T ′) adequate for LHC Run II. Our analysis spans over all of the T′ decay modes (i.e. tZ, th and Wb) where...

Signs of tops from highly mixed stops

Supersymmetric extensions of the Standard Model with highly mixed squark flavours beyond minimal flavour violation provide interesting scenarios of new physics, which have so far received limited attention. We propose a calculable realization of such scenarios in models of gauge mediation augmented with an extra interaction between the messengers and the up type squark. We...

Cornering diphoton resonance models at the LHC

We explore the ability of the high luminosity LHC to test models which can explain the 750 GeV diphoton excess. We focus on a wide class of models where a 750 GeV singlet scalar couples to Standard Model gauge bosons and quarks, as well as dark matter. Including both gluon and photon fusion production mechanisms, we show that LHC searches in channels correlated with the diphoton...

LHC top partner searches beyond the 2 TeV mass region

We propose a new search strategy for heavy top partners at the early stages of the LHC run-II, based on lepton-jet final states. Our results show that final states containing a boosted massive jet and a hard lepton, in addition to a top quark and possibly a forward jet, offer a new window to both detecting and measuring top partners of mass ∼ 2TeV. Our resulting signal...

Boosted event topologies from TeV scale light quark composite partners

We propose a new search strategy for quark partners which decay into a boosted Higgs and a light quark. As an example, we consider phenomenologically viable right handed up-type quark partners of mass ∼ 1 TeV in composite pseudo-Nambu-Goldstone-boson Higgs models within the context of flavorful naturalness. Our results show that S/B > 1 and signal significance of ∼ 7σ is...

A comprehensive approach to dark matter studies: exploration of simplified top-philic models

Studies of dark matter lie at the interface of collider physics, astrophysics and cosmology. Constraining models featuring dark matter candidates entails the capability to provide accurate predictions for large sets of observables and compare them to a wide spectrum of data. We present a framework which, starting from a model Lagrangian, allows one to consistently and...

Higher-order QCD predictions for dark matter production at the LHC in simplified models with s-channel mediators

Weakly interacting dark matter particles can be pair-produced at colliders and detected through signatures featuring missing energy in association with either QCD/EW radiation or heavy quarks. In order to constrain the mass and the couplings to standard model particles, accurate and precise predictions for production cross sections and distributions are of prime importance. In...

Playing tag with ANN: boosted top identification with pattern recognition

Many searches for physics beyond the Standard Model at the Large Hadron Collider (LHC) rely on top tagging algorithms, which discriminate between boosted hadronic top quarks and the much more common jets initiated by light quarks and gluons. We note that the hadronic calorimeter (HCAL) effectively takes a “digital image” of each jet, with pixel intensities given by energy...

Boosting the standard model Higgs signal with the Template Overlap Method

We show that the Template Overlap Method can improve the signal to background ratio of boosted h → \( b\overline{b} \) events produced in association with a leptonically decaying W. We introduce several improvements on the previous formulations of the template method. Varying three-particle template subcones increases the rejection power against the backgrounds, while the...

Measuring boosted tops in semi-leptonic \( t\overline{t} \) events for the standard model and beyond

We present a procedure for tagging boosted semi-leptonic \( t\overline{t} \) events based on the Template Overlap Method. We introduce a new formulation of the template overlap function for leptonically decaying boosted tops and show that it can be used to compensate for the loss of background rejection due to reduction of b-tagging efficiency at high p T . A study of asymmetric...