Related papers: Prospects on Compositeness and New Vector Bosons a…
Fermion compositeness, and other types of new physics that can be described by the exchange of very massive particles, can manifest themselves as the result of an effective four-fermion contact interaction. In the case of the processes…
Fermion compositeness and other new physics can be signalled by the presence of a strong four-fermion contact interaction. Here we present a study of $\ell\ell qq$ and $\ell\ell\ell'\ell'$ contact interactions using the reactions: $\ell^+…
For the processes e+e-\to \mu+\mu-, \tau+\tau-, b\bar{b} and c\bar{c} at a future e+e- collider with \sqrt{s}=0.5 TeV, we examine the sensitivity of the helicity cross sections to four-fermion contact interactions. If longitudinal…
We discuss contact-interaction searches in the processes e^+e^-\to \mu^+\mu^-, b\bar{b} and c\bar{c} at an e^+e^- Linear Collider with c.m. energy \sqrt{s}=0.5 TeV and with longitudinally polarized beams. The measurement of polarized cross…
We discuss the sensitivity to four-fermion contact interactions of the process of fermion-pair production at the e^+ - e^- Linear Collider (LC), with E_{CM}=0.5 TeV and longitudinally polarized electron beam. The analysis is based on…
We consider the possibility of new physics giving rise to effective interactions of the form $e^+e^-Hf \bar f$, where $f$ represents a charged lepton $\ell$ or a (light) quark $q$, and $H$ the recently discovered Higgs boson. Such vertices…
We investigate the quantum properties of heavy-fermion pairs, such as $t\bar t$ or $\tau^+\tau^-$, produced in lepton-lepton collisions with polarised beams. Focusing on spin correlations, entanglement, Bell-inequality violation, and…
Recently proposed Future Circular Collider based muon-proton colliders will allow investigating lepton-hadron interactions at the highest center-of-mass energy. In this study, we investigate the potential of these colliders for a…
I give an overview of the ability of a high energy $\mu^+\mu^-$ collider to discover new particles and interactions. I start with heavy fermions which will be the most straightforward to produce and observe. I then discuss single leptoquark…
For contact-interaction searches at the Linear Collider, we discuss the advantages of polarizing both the electron and the positron beams as compared with polarizing only the electron beam. In particular, for the processes e^+e^-\to…
Heavy neutral gauge boson $Z^\prime$ is proposed in many new physics models. It has rich phenomena at the future muon collider. We study the properties of $Z^\prime$ boson with the process of $\mu^+ \mu^- \rightarrow q \bar{q}$, $\mu^+…
The sensitivity to the $Z^\prime$ couplings of the processes $e^+e^-\to l^+l^-,\bar{b}b$ and $\bar{c}c$ at the linear collider with $\sqrt{s}=500 GeV$ with initial beam polarization, for typical extended model examples are studied. To this…
Numerous non-standard dynamics are described by contact-like effective interactions that can manifest themselves through deviations of the cross sections from the Standard Model predictions. If one such deviation were observed, one should…
A new physics scenario shows that four-fermion operators of Nambu-Jona-Lasinio (NJL) type have a strong-coupling UV fixed point, where composite fermions $F$ (bosons $\Pi$) form as bound states of three (two) SM elementary fermions and they…
$Z^\prime$ boson as a new gauge boson has been proposed in many new physics models. The interactions of $Z^\prime$ coupling to fermions are detailed studied at the large hadron collider. A $Z^\prime$ with the mass of a few TeV has been…
Contactlike nonstandard effective interactions can be revealed through deviations of observables from the Standard Model predictions. If such deviations were observed, the relevant source should be identified among the possible models that…
In a first step, we explore the discovery and analysis potentials of the HERA collider, with and without polarized beams, in the search for electron-quark compositeness in the neutral current channel. Then we study the parity violating…
A future $e^+e^-$ collider could run at the Z-pole to perform important electroweak (EW) precision measurements, while such a run may not be viable for a future muon collider. This however can be compensated by the measurements of other EW…
The production of heavy mass resonances has been widely studied theoretically and experimentally. Several extensions of the standard model (SM) of particle physics, naturally give rise to a new resonance, with neutral electric charge,…
The main possibilities of investigation of leptons and bosons birth in interaction of polarized photons are considered. The usage of $\gamma \gamma \to f \bar{f} [+\gamma]$ reactions for the luminosity measurement on linear photon collider…