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Sphalerons in composite and non-standard Higgs models.

Spannowsky, Michael and Tamarit, Carlos (2017) 'Sphalerons in composite and non-standard Higgs models.', Physical review D., 95 (1). 015006.


After the discovery of the Higgs boson and the rather precise measurement of all electroweak boson’s masses the local structure of the electroweak symmetry breaking potential is already quite well established. However, despite being a key ingredient to a fundamental understanding of the underlying mechanism of electroweak symmetry breaking, the global structure of the electroweak potential remains entirely unknown. The existence of sphalerons, unstable solutions of the classical action of motion that are interpolating between topologically distinct vacua, is a direct consequence of the Standard Model’s SU ( 2 ) L gauge group. Nevertheless, the sphaleron energy depends on the shape of the Higgs potential away from the minimum and can therefore be a litmus test for its global structure. Focusing on two scenarios, the minimal composite Higgs model SO ( 5 ) / SO ( 4 ) or an elementary Higgs with a deformed electroweak potential, we calculate the change of the sphaleron energy compared to the Standard Model prediction. We find that the sphaleron energy would have to be measured to O ( 10 ) % accuracy to exclude sizeable global deviations from the Standard Model Higgs potential. We further find that because of the periodicity of the scalar potential in composite Higgs models a second sphaleron branch with larger energy arises.

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Publisher statement:Reprinted with permission from the American Physical Society: Spannowsky, Michael & Tamarit, Carlos (2017). Sphalerons in composite and non-standard Higgs models. Physical Review D 95(1): 015006 © 2017 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modified, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.
Date accepted:No date available
Date deposited:25 May 2017
Date of first online publication:10 January 2017
Date first made open access:25 May 2017

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