Related papers: Heavy fermions virtual effects at e^+ e^- collider…

Electromagnetic (EM) interactions are incorporated in a recently proposed effective field theory of the nuclear many-body problem. Earlier work with this effective theory exhibited EM couplings that are correct only to lowest order in both…

In the last decades electroweak processes were studied at hadron and lepton colliders. By exploiting the large statistics and the c.o.m. energy available, hadron colliders played a significant role in performing precision measurements of…

One leading source of uncertainty in the lattice computation of semi-leptonic form factors in B decay, and to a lesser extent B meson decay constants, comes from the extrapolation of the light quark mass to the physical up/down mass. This…

We consider the effects of a number of models with one extra $Z$, with enhanced couplings to quarks, in the final \underline{hadronic} channels at LEP2. We show that, for a number of representative cases, visible effects could be produced…

We perform a detailed study of the process $e^+e^-\to \mu^+\mu^-\nu_l\bar\nu_l$ including all contributions. The contributions other than from real gauge boson production leads to a rich phenomenology. We explore the use of the process as a…

This report summarises the results of the four-fermion working group of the LEP2-MC workshop, held at CERN from 1999 to 2000. Recent developments in the calculation of four-fermion processes in electron-positron collisions at LEP-2…

Electromagnetic interactions are introduced in the effective chiral Lagrangian for heavy mesons which includes light vector particles. A suitable notion of vector meson dominance is formulated. The constraints on the heavy meson -light…

A dynamical symmetry breaking model of electroweak interactions is investigated based on strongly interacting fermions. Vector-like fermions of different representations of the weak SU(2) form a symmetry breaking condensate and generate the…

Possibilities for detecting heavy Majorana neutrinos ($N$'s) at future $e{\mu}$ colliders are investigated. In contrast to the $e^-e^+$ colliders (LEP200 and NLC), the center-of-mass (CMS) energies achieved at $e{\mu}$ colliders can be much…

Heavy vector-like quarks (VLQs) appear in many models of beyond the Standard Model physics. Direct experimental searches require these new quarks to be heavy, $\gsim$ 800-1000 GeV. We perform a global fit of the parameters of simple VLQ…

We compute the total cross-section and invariant mass distribution for heavy-quark pair production in $e^+e^-$ annihilation at the next-to-next-to-next-to-leading order in QCD. The obtained results are expressed as piecewise functions…

New physics associated with the heavy top quark can affect top quark production and the partial decay width of $Z \rightarrow b \bar b$. In this paper, we examine the correlated effects of possible new physics on ${R_b}$ measured at LEP I…

We consider the physics of an extra $U(1)$ gauge boson $Z'$, which can mix with $Z$ through intermediate fermion loops. The loop contribution due to the heavy top quark significantly affects the low-energy observables, and for $m_{Z'}>m_Z$,…

We discuss the process $\ell^+\ell^- \to N W^{\pm} \ell^{\mp}$, where $N$ is a heavy Majorana neutrino and $\ell = e, \mu$. Large cross sections are expected for these processes at high center-of-mass energies, which can be reached at…

Inspired by a new class of walking technicolor models recently proposed using higher-dimensional technifermions, we consider the oblique corrections from heavy non-degenerate fermions with two classes of higher-dimensional representations…

We analyze the potential of the Next Linear $e^+e^-$ Collider to study anomalous quartic vector-boson interactions through the processes $e^+ e^- \to W^+W^-Z$ and $ZZZ$. In the framework of $SU(2)_L \otimes U(1)_Y$ chiral Lagrangians, we…

We investigated the effect of the light fermion masses on cross sections for e^+e^- into 4 fermions in the Fermion Loop scheme defined in hep-ph/9612260, and approximations to it. The effects are found to be very small, except of course in…

We propose a model with two Higgs doublets and several $SU(2)$ scalar singlets with a global non-Abelian flavor symmetry $\mathcal{Q}_6\times\mathcal{Z}_2$. This discrete group accounts for the observed pattern of fermion masses and mixing…

We present preliminary results from our calculation of the low energy constants (LECs) of the chiral effective theory for 3, 4 and 5 color QCD with $N_f=2$ dynamical fermion flavors. We simulate with clover fermions over a range of lattice…

The future linear collider will collide dense $e^+e^-$ bunches at high energies up to 1 TeV, generating very intense electromagnetic fields at the interaction point (IP). These fields are strong enough to lead to nonlinear effects which…