Related papers: Light Fermion Mass Effects in e^+e^- -> 4 Fermions
We observe an obvious anomalous line-shape of the $e^+e^- \to {\rm hadrons}$ total cross sections in the energy region between 3.700 and 3.872 GeV from the data samples taken with the BES-II detector at the BEPC Collider. Re-analysis of the…
We apply the light-cone technique to electroproduction reaction $ep\to e\pi^+n$ long considered as a means of measuring the electromagnetic form factor of the pion. We show that the interpretation of the long-standing puzzle of large…
The dominant electroweak corrections to the production cross sections and partial decay widths of a light Standard-Model Higgs boson, with mass M_H << 2m_t, are due to top-quark loops. By means of a low-energy theorem, we study at the…
We compute the leading logarithmic behaviour of the cross-section for the production of a pseudoscalar Higgs boson in gluon-gluon fusion to all-orders in perturbation theory, in the limit of large partonic centre of mass energy. We also…
Precision studies at electron-positron colliders with center-of-mass energies in the charm-tau region and below have strongly contributed to our understanding of light-meson interactions at low energies. We focus on the processes involving…
In this article, we consider the propagation of QED fermions in the presence of a classical background magnetic field with white-noise stochastic fluctuations. The effects of the magnetic field fluctuations are incorporated into the fermion…
Analytic results for the next-to-leading order electroweak radiative corrections to the decay of the polarised $W$ boson into a pair of heavy quarks are presented. Finite fermion masses are taken into account throughout this calculation,…
We investigate the forward-backward asymmetries in the pair production of fourth family fermions through the new Z' interactions in the e+e- collisions. The Z' boson having family universal couplings can contribute to the pair production of…
The contributions to heavy meson mass differences by the strong hyperfine interaction, the light quark masses and the electromagnetic interaction are obtained from the empirical values of the $D$, $D^*$, $B$ and $B^*$ masses by means of a…
A contact four-fermion interaction between light quarks and electrons has been evoked as a possible explanation for the excess of events observed by HERA at high-$Q^2$. We explore the 1-loop effects of such interaction in $\Gamma(Z^0 \to…
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…
We give a model-independent discussion of fermion masses in four-dimensional heterotic superstring theories. We discuss the tree level contributions and quantum corrections, including one-loop threshold effects and masses generated as a…
The various four-fermion production channels in $e^+ e^-$ annihilation are discussed and the {\tt CC11} process $e^+ e^- \rightarrow {\bar f}_1^u f_1^d f^u_2 {\bar f}_2^d$, {\mbox{$f$$\neq$$e$}}, is studied in detail. The cross section…
We study electromagnetic as well as strong isospin breaking effects in the isospin mass splittings of light pseudoscalar and vector mesons. To this end we employ a coupled system of quark Dyson-Schwinger and meson Bethe-Salpeter equations…
We present new results for light quark masses. The calculations are performed using two flavours of $O(a)$ improved Wilson fermions. We have reached lattice spacings as small as $a \sim 0.07$fm and pion masses down to $m_{\pi} \sim 340$MeV…
In a recent paper we used chiral perturbation theory to determine the phase diagram and pion spectrum for Wilson and twisted-mass fermions at non-zero lattice spacing with non-degenerate up and down quarks. Here we extend this work to…
Using data corresponding to an integrated luminosity of $651~\mathrm{pb}^{-1}$ accumulated at 22 center-of-mass energies from 2.00 to 3.08 GeV by the BESIII experiment, the process $e^{+}e^{-}\to\phi\pi^{+}\pi^{-}$ is studied. The cross…
We test the assumption that fermion-loop corrections to high energy $W^+W^-$ scattering are negligible when compared to the boson-loop ones. Indeed, we find that, if the couplings of the interactions deviate from their Standard Model…
The MILC Collaboration has completed production running of electromagnetic effects on light mesons using asqtad improved staggered quarks. In these calculations, we use quenched photons in the noncompact formalism. We study four lattice…
We studied single $W$ boson production in high energy $e\gamma$ collisions and the sensitivity of various observables to the $WW\gamma$ vertex. We included gauge boson decay to final state fermions and all contributions to the same final…