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This note presents constraints on Standard Model parameters using published and preliminary precision electroweak results measured at the electron-positron colliders LEP and SLC. The results are compared with precise electroweak…

We show how the processes $e^- e^+ \to ZH, ~ \gamma H$, which will be studied at LEP2 and at high energy colliders, could be used to search for types of New Physics (NP) characterized by an effective NP scale in the few TeV range and…

High Energy Physics - Phenomenology · Physics 2009-10-28 G. J. Gounaris , F. M. Renard , N. D. Vlachos

We examine the potential of the process $ep \rightarrow e\gamma^{*} \gamma^{*} p\rightarrow e\tau \bar{\tau}p$ at the Large Hadron Electron Collider (LHeC) and the Future Circular Hadron Electron Collider (FCC-he) to examine non-standard…

High Energy Physics - Phenomenology · Physics 2019-05-08 M. Köksal

We consider lepton-antilepton annihilation into a fermion-antifermion pair at variable c.m. energy. We propose for this process a simple parametrization of the virtual effects of the most general model of new physics of…

High Energy Physics - Phenomenology · Physics 2009-10-31 M. Beccaria , F. M. Renard , S. Spagnolo , C. Verzegnassi

A data sample corresponding to an integrated luminosity of 232pb^-1 was collected in 1997 and 1998 by the L3 experiment at LEP in e+e- collisions at centre-of-mass energies between 181.7GeV and 188.7GeV. Pair production of fermions and…

High Energy Physics - Experiment · Physics 2007-05-23 Salvatore Mele

New physics interactions beyond the Standard Model can make themselves known as small corrections to Standard Model reactions. There is a diverse array of proposals for new physics, and so any parametrization of those effects must be as…

High Energy Physics - Phenomenology · Physics 2020-03-12 Michael E. Peskin

Given the absence of direct evidence for new resonances beyond the Standard Model (BSM) at the Large Hadron Collider (LHC) so far, a complementary strategy to search for new physics in an indirect way is provided by the Standard Model…

High Energy Physics - Phenomenology · Physics 2025-01-16 Jaco ter Hoeve

This note presents constraints on Standard Model parameters using published and preliminary precision electroweak results measured at the electron-positron colliders LEP and SLC. The results are compared with precise electroweak…

We discuss the impact of precision measurements of $\sigma(e^+e^-\to {hadrons})$ in the center-of-mass range between 3 and 12 GeV, including improvements in the electronic widths of the narrow charmonium and bottonium resonances, on the…

High Energy Physics - Phenomenology · Physics 2009-11-07 J. H. Kühn , M. Steinhauser

We study the helicity amplitudes of the process gamma gamma to ZZ in the Standard Model at high energy. These amplitudes receive contributions from the W and charged quark and lepton loops, analogous to those encountered in the gamma gamma…

High Energy Physics - Phenomenology · Physics 2015-06-25 G. J. Gounaris , J. Layssac , P. I. Porfyriadis , F. M. Renard

We study predictions for the reaction $e^+e^- \to {\bar \nu} \nu (n \gamma)$. The complete one-loop corrections are taken into account and higher order contributions, in particular those for the observed real photons, are added whenever…

High Energy Physics - Phenomenology · Physics 2011-09-13 D. Bardin , S. Jadach , T. Riemann , Z. Was

One of purposes for High Energy accelerator experiments is confrontation of theory and measurements in ever new realms. Any new agreement extends theory applicability domain, any discrepancy hints to unexplained. That calls for better…

High Energy Physics - Phenomenology · Physics 2025-07-23 Z. Was

The complementarity of $e^+e^-$ and $\gamma \gamma$ colliders to discover and explore new physics beyond the Standard Model(SM) is discussed. After briefly surveying a number of various new physics scenarios we concentrate in detail on…

High Energy Physics - Phenomenology · Physics 2009-10-31 Thomas G. Rizzo

We summarize the indirect effects of new physics in a variety of processes. We consider precision electroweak measurements, the $g-2$ of the muon, rare decays, meson mixing, CP violation, lepton number violating interactions, double beta…

High Energy Physics - Phenomenology · Physics 2007-05-23 J. L. Hewett , T. Takeuchi , S. Thomas

Precision experiments at low energies probing weak interaction are a very promising and complementary tool for investigating the structure of the electro-weak sector of the standard model, and for searching for new phenomena revealing signs…

High Energy Physics - Experiment · Physics 2010-02-25 Stephan Paul

The precise measurement of physics observables and the test of their consistency within the standard model (SM) are an invaluable approach, complemented by direct searches for new particles, to determine the existence of physics beyond the…

Compton scattering of quasi-real virtual photons, gamma e+- -> gamma e+-, is studied with 0.6fb-1 of data collected by the L3 detector at the LEP e+e- collider at centre-of-mass energies root(s')=189-209GeV. About 4500 events produced by…

High Energy Physics - Experiment · Physics 2012-08-27 L3 Collaboration

Muon lepton flavor processes are reviewed in connection with search for physics beyond the standard model. Several methods to distinguish different theoretical models are discussed for $\mu \to e \gamma$, $\mu \to 3 e$, and $\mu - e$…

High Energy Physics - Phenomenology · Physics 2007-05-23 Yasuhiro Okada

Advantages of the e-e- option at linear colliders for the study of supersymmetry are highlighted. The fermion number violating process $e^- e^- \to \selectron^- \selectron^-$ provides unique opportunities for studies of slepton masses and…

High Energy Physics - Phenomenology · Physics 2014-11-17 Jonathan L. Feng

I present a brief overview of the advantages of using a consistent effective Lagrangian approach in parameterizing virtual new physics effects. I then apply the formalism to certain top-quark processes.

High Energy Physics - Phenomenology · Physics 2011-01-25 Jose Wudka