Complementarity of μTRISTAN and Belle II in searches for charged-lepton flavour violation

We analyse the potential of the proposed μ+μ+ and μ+e− collider μTRISTAN to complement the searches for charged-lepton flavour-violation (CLFV) that can be carried out by Belle II. μTRISTAN offers the possibility of directly producing and studying new resonances that could mediate CLFV for a certain...

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Main Authors: Gabriela Lichtenstein, Michael A. Schmidt, German Valencia, Raymond R. Volkas
Format: Article
Language:English
Published: Elsevier 2023-10-01
Series:Physics Letters B
Online Access:http://www.sciencedirect.com/science/article/pii/S0370269323004781
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author Gabriela Lichtenstein
Michael A. Schmidt
German Valencia
Raymond R. Volkas
author_facet Gabriela Lichtenstein
Michael A. Schmidt
German Valencia
Raymond R. Volkas
author_sort Gabriela Lichtenstein
collection DOAJ
description We analyse the potential of the proposed μ+μ+ and μ+e− collider μTRISTAN to complement the searches for charged-lepton flavour-violation (CLFV) that can be carried out by Belle II. μTRISTAN offers the possibility of directly producing and studying new resonances that could mediate CLFV for a certain range of masses. In addition, we find that it can produce competitive bounds to those from Belle II for cases where the new resonance lies beyond direct reach. We illustrate these points with three Z3 “lepton triality” models, where we also find an example that can only be probed by μTRISTAN. These three models feature doubly-charged scalars, denoted k1,2,3 respectively, that induce both CLFV and flavour-conserving processes. Tree-level k1 exchange induces the CLFV scattering process μ+e−→e+τ−, while k2 interactions induce μ+μ+→τ+e+, μ+e−→τ+μ− and make a non-SM contribution to the flavour-conserving scattering μ+μ+→μ+μ+. The k3 model has a non-SM contribution to the flavour-conserving process μ+e−→μ+e−. Other scattering processes involving k1, k2 or k3 are not relevant for μTRISTAN and outside the scope of our analysis. We quantify the sensitivity of μTRISTAN for each of these processes. For the k1 and k2 cases we compare the μTRISTAN reach to the expected sensitivity of Belle II to the crossing symmetry related CLFV τ decays.
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spelling doaj.art-c24c1c4c2de6461084f3f000bc8d4ed82023-09-23T05:10:26ZengElsevierPhysics Letters B0370-26932023-10-01845138144Complementarity of μTRISTAN and Belle II in searches for charged-lepton flavour violationGabriela Lichtenstein0Michael A. Schmidt1German Valencia2Raymond R. Volkas3Sydney Consortium for Particle Physics and Cosmology, School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia; Corresponding author.Sydney Consortium for Particle Physics and Cosmology, School of Physics, The University of New South Wales, Sydney, New South Wales 2052, AustraliaSchool of Physics and Astronomy, Monash University, Wellington Road, Clayton, Victoria 3800, AustraliaARC Centre of Excellence for Dark Matter Particle Physics, School of Physics, The University of Melbourne, Victoria 3010, AustraliaWe analyse the potential of the proposed μ+μ+ and μ+e− collider μTRISTAN to complement the searches for charged-lepton flavour-violation (CLFV) that can be carried out by Belle II. μTRISTAN offers the possibility of directly producing and studying new resonances that could mediate CLFV for a certain range of masses. In addition, we find that it can produce competitive bounds to those from Belle II for cases where the new resonance lies beyond direct reach. We illustrate these points with three Z3 “lepton triality” models, where we also find an example that can only be probed by μTRISTAN. These three models feature doubly-charged scalars, denoted k1,2,3 respectively, that induce both CLFV and flavour-conserving processes. Tree-level k1 exchange induces the CLFV scattering process μ+e−→e+τ−, while k2 interactions induce μ+μ+→τ+e+, μ+e−→τ+μ− and make a non-SM contribution to the flavour-conserving scattering μ+μ+→μ+μ+. The k3 model has a non-SM contribution to the flavour-conserving process μ+e−→μ+e−. Other scattering processes involving k1, k2 or k3 are not relevant for μTRISTAN and outside the scope of our analysis. We quantify the sensitivity of μTRISTAN for each of these processes. For the k1 and k2 cases we compare the μTRISTAN reach to the expected sensitivity of Belle II to the crossing symmetry related CLFV τ decays.http://www.sciencedirect.com/science/article/pii/S0370269323004781
spellingShingle Gabriela Lichtenstein
Michael A. Schmidt
German Valencia
Raymond R. Volkas
Complementarity of μTRISTAN and Belle II in searches for charged-lepton flavour violation
Physics Letters B
title Complementarity of μTRISTAN and Belle II in searches for charged-lepton flavour violation
title_full Complementarity of μTRISTAN and Belle II in searches for charged-lepton flavour violation
title_fullStr Complementarity of μTRISTAN and Belle II in searches for charged-lepton flavour violation
title_full_unstemmed Complementarity of μTRISTAN and Belle II in searches for charged-lepton flavour violation
title_short Complementarity of μTRISTAN and Belle II in searches for charged-lepton flavour violation
title_sort complementarity of μtristan and belle ii in searches for charged lepton flavour violation
url http://www.sciencedirect.com/science/article/pii/S0370269323004781
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