A few thoughts on eee Chih-Hsiang Cheng, Bertrand Echenard, David - - PowerPoint PPT Presentation

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Feb 01, 2023 242 likes •325 views

A few thoughts on eee Chih-Hsiang Cheng, Bertrand Echenard, David Hitlin, Frank Porter California Institute of Technology Intensity frontier workshop Argonne April 2013 Probing Lorentz structure of New Physics Y. Okada et al. , PRD 61

SLIDE 1

A few thoughts on µ→eee

Chih-Hsiang Cheng, Bertrand Echenard, David Hitlin, Frank Porter

California Institute of Technology Intensity frontier workshop Argonne – April 2013

SLIDE 2

Bertrand Echenard Intensity frontier Workshop - April 2013 p.2

Probing Lorentz structure of New Physics

Dalitz plot of µ→eee defined with help of the muon polarization carry information on chirality and Lorentz structure of CLFV couplings (same for τ→µµµ) Generic Lagrangian Positron 1 vs Positron 2 (E1 > E2) xi = 2Ei /mµ

AR,L photon-penguin coupling, contributes to µ→eγ, µ→eee gi 4-point contact interaction, contributes to µ→eee

Need at least dozens of events and a polarized muons

Y. Okada et al., PRD 61 (200) 094001

SLIDE 3

Bertrand Echenard Intensity frontier Workshop - April 2013 p.3

Probing Lorentz structure of New Physics

Similar situation in τ→µµµ

B.M. Dassinger et al., JHEP 0710 (2007) 039

Need at least dozens of events and a polarized taus

SLIDE 4

Bertrand Echenard Intensity frontier Workshop - April 2013 p.4

Reference: the mu3e experiment

Reference: the mu3e design

Achieve a µ→eee mass resolution ~ 520 keV Time resolution ~50 ps (tile) / ~500 ps (fiber)

N. Berger
N. Berger

arXiv:1301:6113

SLIDE 5

Bertrand Echenard Intensity frontier Workshop - April 2013 p.5

Sensitivity of mu3e experiment

Accidental background not shown here, level similar to µ→eeeνν in size but flat in mass

Need to beat down these backgrounds → better timing and mass resolution

N. Berger

Mu3e goal

SLIDE 6

Bertrand Echenard Intensity frontier Workshop - April 2013 p.6

Active target

An active target could help by further constraining the decay vertex and improving the time resolution. This would

reduce the accidentals (typically a few muon decay / ns in target)
improve mass resolution, thus reducing the µ→eeeνν background

See D. Brown talk on active target

SLIDE 7

Bertrand Echenard Intensity frontier Workshop - April 2013 p.7

FastSim

Simulation of prototype detector for µ→eγ with FastSim Use the same tool to simulate a detector for µ→eee with an active target. see C.H. Cheng talk on µ→eγ Chih-Hsiang Cheng

SLIDE 8

Bertrand Echenard Intensity frontier Workshop - April 2013 p.8

Outlook

Plan to study a “mu3e-like” configuration with FastSim using an active target to see if we can

improve the mass resolution
Improve the accidentals rejection

A few thoughts on µ→eee

Chih-Hsiang Cheng, Bertrand Echenard, David Hitlin, Frank Porter

California Institute of Technology Intensity frontier workshop Argonne – April 2013

Probing Lorentz structure of New Physics

Dalitz plot of µ→eee defined with help of the muon polarization carry information on chirality and Lorentz structure of CLFV couplings (same for τ→µµµ) Generic Lagrangian Positron 1 vs Positron 2 (E1 > E2) xi = 2Ei /mµ

AR,L photon-penguin coupling, contributes to µ→eγ, µ→eee gi 4-point contact interaction, contributes to µ→eee

Need at least dozens of events and a polarized muons

Probing Lorentz structure of New Physics

Similar situation in τ→µµµ

B.M. Dassinger et al., JHEP 0710 (2007) 039

Need at least dozens of events and a polarized taus

Reference: the mu3e experiment

Reference: the mu3e design

Achieve a µ→eee mass resolution ~ 520 keV Time resolution ~50 ps (tile) / ~500 ps (fiber)

arXiv:1301:6113

Sensitivity of mu3e experiment

Accidental background not shown here, level similar to µ→eeeνν in size but flat in mass

Need to beat down these backgrounds → better timing and mass resolution

Mu3e goal

Active target

An active target could help by further constraining the decay vertex and improving the time resolution. This would

See D. Brown talk on active target

FastSim

Simulation of prototype detector for µ→eγ with FastSim Use the same tool to simulate a detector for µ→eee with an active target. see C.H. Cheng talk on µ→eγ Chih-Hsiang Cheng

Outlook

Plan to study a “mu3e-like” configuration with FastSim using an active target to see if we can

Explore alternative geometries Any good idea is welcome.