The Future Circular Collider (FCC-ee), with its clean experimental environment, high energy, and luminosity, offers a unique opportunity for the precise study of the properties and interactions of TOP QUARKs. In this study, we have investigated the potential sensitivity of the FCC-ee to flavor-changing neutral current (FCNC) processes involving TOP QUARKs using an effective Lagrangian approach. To this end, the production of TOP QUARKs in electron-positron collisions at center-of-mass energies of 240 GeV and 365 GeV has been simulated, considering the full hadronic decay of the W boson resulting from the TOP QUARK decay. The results of the analyses show that by combining these center-of-mass energies and considering integrated luminosities of 5 ab⁻¹ and 1.5 ab⁻¹, an FCNC sensitivity on the order of 10⁻⁵ can be achieved. These findings highlight the significant potential of the FCC-ee for discovering and precisely studying FCNC processes, which could contribute to a better understanding of physics beyond the Standard Model.

In this paper, we present a detailed study to probe TOP-QUARK flavor changing neutral current (FCNC) interactions at, , and vertices with TOP-QUARK pair in association with a photon and three-TOP-QUARKs signal at the Large Hadron Collider (LHC). We investigate the TOP-QUARK FCNC couplings and carry out a full simulation for the triple-TOP production considering the main backgrounds. In addition, having at hand the cross section of a TOP-QUARK pair produced in association with a photon in collisions at a centre-of-mass energy of 8 TeV with 20. 2 of data collected by the ATLAS detector, we also investigated the FCNC coupling. The obtained exclusion limits on coupling strengths and branching ratios are summarized and compared with the results in literature. The discovery potential for anomalous couplings, , and with an integrated luminosity of are also examined in detail. We show that, for higher luminosities within Run-II of LHC, a dedicated search for the TOP-QUARK FCNC couplings can achieve comparable or even better sensitivities to the triple-TOP signal than the other TOP-QUARK production scenarios. We have shown that the triple-TOP signal could potentially provide evidence for new physics at the LHC.

The study of polarized TOP QUARK decay could be considered as a new channel to search for new physics. According to the Standard Model (SM) of particle physics, TOP QUARK in a cascade process as decays into a bottom QUARK and -boson so in the following, -boson decays in a lepton pair (or a QUARK-antiQUARK) and bottom hadronizes into an observable bottom-flavored hadron (in most cases a B-meson). Through this paper, we first present an overview on the polarized TOP QUARK decay and then study the azimuthal correlation between the event plane, formed by the vectors , and the polar plane constructed by the vectors . We will investigate the effect of right-chiral QUARK current which is absent in the SM. We will show that this non-SM effect leads to nonzero values for the azimuthal correlation contribution at leading-order perturbation theory.

A search for SUSY using the TOP QUARK plus missing transverse energy (MET), in a low mass mSUGRA test point is performed. A two–constraints kinematic fit is utilized to extract the TOP QUARK, either b-jet the ones that is recognizable or it is not recognizable. It is shown that for point LM1, for the former situation, a 5σ excess can be achieved with 30 pb-1; and for the latter situation, it can be observed with 9.6 pb-1. The ratio of the final signal over background for both situations is 12.0.

The existence of a new massive charged gauge boson, known as W’, is proposed by many new physics scenarios. When W’ decays to tb, the final state is very similar to the final state of the s-channel single TOP production, where W boson is the off-shell mediator to produce the TOP and bottom QUARKs. If W exists, it can affect the cross section of the SM schannel single TOP production, so measuring this cross section can constrain the W’ contribution. We use different data categories from CMS and ATLAS experiments to constrain this contribution. Assuming a pure left-handed (righthanded) W’ gives a lower limit of 1290 (1360) GeV at 95% Confidence Level on the mass of W’. If the coupling coefficient is increased to 1.8, the lower limit on the W’ mass can exceed 1900 GeV, in special cases.

Two aspects of b-QUARK decays are investigated. First, according to the structure of penguin decays and second, according to the Effective Hamiltonian theory. In this work, the gluonic penguin term is calculated according to the structure of penguin for various b and `b QUARK decays. The total gluonic penguin amplitude to lowest order in as is used for the decay process, b®qkg ®qkq’`q (qkqi`q)i=j. The magnetic dipole gluonic penguin term for various b QUARK decays is calculated. The tree-level and gluonic penguin terms of b-QUARK are also added to calculated the decay rates of b and `b QUARK. It is shown that the gluonic penguin term is small for some decay. The decay rates of processes like b®cd`c (`b®cd`c(`b®`c`d),b®cs`c(`b®`c`sc) and b®us`u,(`b®`u`su) is obtained.

We investigate the physical properties of QUARK stars with two different equations of state in generalized hybrid metric-Palatini gravity. This theory corresponds to a bi-scalar gravitational theory with two non-minimally-coupled scalar fields.The field equations of the metric tensor and scalar fields are derived by varying the action with respect to the dynamical fields. We obtain the field equations for static spherically symmetric geometry interior of compact objects. The numerical solutions for two types of QUARK stars, the MIT bag and CFL model are studied. The solutions reveal the structure of the compact objects. The solutions are obtained for different values of the model parameters. All considered cases show that compact objects are more massive than their general relativity counterpart. The surface redshift and compactness are also obtained which shows that the generalized hybrid metric-Palatini QUARK stars have higher surface redshift and are more compact than general relativity QUARK stars.