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Precision measurement constraints on the 4-Site model & the effect of interference in searches for new physics

Precision measurement constraints on the 4-Site model & the effect of interference in searches for new physics
Precision measurement constraints on the 4-Site model & the effect of interference in searches for new physics
This work is divided in two parts.

The first part presents a careful computation of Electroweak Precision Tests constraints on the 4-Site model, and the resulting limits on fermion couplings. The new heavy W and Z bosons present in this model can couple significantly to Standard Model fermions.

Previous computations of these quantities were performed using an approximation that is here shown to have a more restricted validity domain as what was originally thought.

The second part of the discussion is about searches of extra W and Z bosons as predicted in some extensions of the Standard Model (such as the 4-Site model) in the Drell-Yan channels.

The interference between the new physics and the Standard Model is commonly neglected in the interpretation of experimental searches. The importance of this effect is investigated in detail. The quantitative error in exclusion bounds due to neglecting the interference may be small, but important qualitative features are missed when using this approximation.

It is important to be aware of the effect of interference in order to make sure wrong statements and bad conclusions are avoided, and to guarantee that analyses do stay within the domain of validity of the approximations they rely on.
Becciolini, Diego
f25f7755-ebb8-48e8-a40a-a962a1c90548
Becciolini, Diego
f25f7755-ebb8-48e8-a40a-a962a1c90548
Accomando, Elena
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Becciolini, Diego (2013) Precision measurement constraints on the 4-Site model & the effect of interference in searches for new physics. University of Southampton, Faculty of Physical Sciences and Engineering, Doctoral Thesis, 113pp.

Record type: Thesis (Doctoral)

Abstract

This work is divided in two parts.

The first part presents a careful computation of Electroweak Precision Tests constraints on the 4-Site model, and the resulting limits on fermion couplings. The new heavy W and Z bosons present in this model can couple significantly to Standard Model fermions.

Previous computations of these quantities were performed using an approximation that is here shown to have a more restricted validity domain as what was originally thought.

The second part of the discussion is about searches of extra W and Z bosons as predicted in some extensions of the Standard Model (such as the 4-Site model) in the Drell-Yan channels.

The interference between the new physics and the Standard Model is commonly neglected in the interpretation of experimental searches. The importance of this effect is investigated in detail. The quantitative error in exclusion bounds due to neglecting the interference may be small, but important qualitative features are missed when using this approximation.

It is important to be aware of the effect of interference in order to make sure wrong statements and bad conclusions are avoided, and to guarantee that analyses do stay within the domain of validity of the approximations they rely on.

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More information

Published date: May 2013
Organisations: University of Southampton, Theoretical Partical Physics Group

Identifiers

Local EPrints ID: 353973
URI: http://eprints.soton.ac.uk/id/eprint/353973
PURE UUID: 11262a0d-9699-4b0d-a090-799c948b8121

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Date deposited: 01 Jul 2013 10:12
Last modified: 14 Mar 2024 14:12

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Contributors

Author: Diego Becciolini
Thesis advisor: Elena Accomando

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