Related papers: Same-sign top pair plus $W$ production in flavor c…
A summary of the recent searches for anomalous single top-quark production and lepton flavour violation in high energy ep collisions is presented. Single top-quark production via an anomalous flavour changing neutral current gamma-u-t…
Following a prediction made in Refs.~\cite{vonBuddenbrock:2015ema,Kumar:2016vut,vonBuddenbrock:2016rmr}, this paper focuses on multi-lepton signatures arising from two new hypothetical scalar bosons, $H$ and $S$, at the Large Hadron…
ATLAS results are presented on a search for flavor-changing neutral currents (FCNC) in top quark decays at the LHC. Events are searched for where a pair of top quarks is produced and one decays through the Standard Model $t \rightarrow Wb$…
We explore scenarios where top quarks may be produced singly in association with missing energy, a very distinctive signature, which in analogy with monojets, we dub monotops. We find that monotops can be produced in a variety of modes,…
The associated production of a single-top with opposite-sign same-flavor (OSSF) di-leptons, $pp \to t \ell^+ \ell^-$ and $ pp \to t \ell^+ \ell^- + j$ ($j=$light jet), can lead to striking tri-lepton $pp \to \ell^\prime \ell^+ \ell^- + X$…
A search is presented for the production of a single top quark via left-handed flavour-changing neutral-current (FCNC) interactions of a top quark, a gluon and an up or charm quark. Two production processes are considered: $u+g\rightarrow…
Due to its high mass top quarks decay before top-flavoured hadrons can be formed. This feature yields experimental access to the top quark polarization and production asymmetries. The large top quark sample moreover enables measurements of…
We investigate models of a heavy neutral gauge boson Z' which could explain anomalies in B meson decays reported by the LHCb experiment. In these models, the Z' boson couples mostly to third generation fermions. We show that bottom quarks…
We demonstrate that flavour-changing neutral currents in the top sector, mediated by leptophilic scalars at the electroweak scale, can easily arise in scenarios of new physics, and in particular in composite Higgs models. We moreover show…
Till today, although the Standard Model (SM) is the most celebrated theory that explains nature almost completely, there are still some phenomena observed in nature that the SM cannot explain. That is why it is needed to look for theories…
A search for flavour-changing neutral current decays of a top quark to an up-type quark ($q=u, c$) and the Standard Model Higgs boson, where the Higgs boson decays to $b\bar{b}$, is presented. The analysis searches for top quark pair events…
We present constraints on Wilson coefficients from a combined fit to data from top-quark and beauty-physics measurements within the Standard Model effective field theory. We consider present data on top-quark pair production and decay,…
We develop the phenomenology of scenarios in which a dark matter candidate interacts with a top quark through flavour-changing couplings, employing a simplified dark matter model with an s-channel vector-like mediator. We study in detail…
I present approximate N$^3$LO theoretical results for top-antitop pair production, and for single-top production in association with a $W$ boson. The higher-order corrections are from soft-gluon radiation, which is dominant near partonic…
The topcolor-assisted technicolor (TC2) model predicts a number of neutral scalars like the top-pion ($\pi^0_t$) and the top-Higgs ($h^0_t$). These scalars have flavor-changing neutral-current (FCNC) top quark couplings, among which the…
We present a systematic study of the different mechanisms leading to WW pair production at the LHC, both in the same-sign and opposite-sign channels, and we emphasize that the former offers much better potential for investigating…
There are theoretical and phenomenological motivations that there may exist additional heavy Z' bosons with family non-universal couplings. Flavor mixing in the quark and lepton sectors will then lead to flavor changing couplings of the…
This paper is an experimental review of the study of processes with a single top quark at the LHC. The pioneering times are over, and this is now a sector of "precision physics" at colliders. Angular distributions of the decay products of…
Flavor changing neutral currents coming from a new non-universal neutral Gauge-Boson and from the non-unitary quark mixing matrix for the $SU(3)_c\otimes SU(3)_L\otimes U(1)_X$ model with right handed neutrinos are studied. By imposing as…
We study in a model-independent way new neutral and charged vector bosons that could give observable signals with leptonic final states at the LHC. We show, in particular, that a charged vector W' decaying into lepton plus neutrino is…