Charged Lepton Flavor Violation in Muon 3 Major Processes + e + - PowerPoint PPT Presentation

The COMET experiment: Search for muon-to-electron conversion Manabu MORITSU (KEK) On behalf of the COMET Collaboration The 3rd J-PARC Symposium (J-PARC2019) 26th Sep., 2019, Tsukuba, Japan

M. Moritsu (KEK) ̶̶ 26/09/2019, J-PARC2019 ! 2 Charged Lepton Flavor Violation in Muon 3 Major Processes • µ + → e + γ • µ + → e + e + e - • µ - N → e - N ( µ -e conversion) SM neutrinos γ 2 Δ m 2 B ( μ → e γ ) = 3 α W ≲ 10 -54 violation has been observed. ∑ i 1 U * μ i U ei Lepton mixing in the SM has BR( µ 2 32 π M W i =2,3 µ ν e ν µ → ν e # due to small mass ratio of neutrino to weak boson Since the SM contribution is negligibly small, Observation of CLFV indicates a clear evidence of New Physics . Large window for BSM sear

M. Moritsu (KEK) ̶̶ 26/09/2019, J-PARC2019 (2008) mu-e Conversion MEG 2016 4.2x10 -13 nuclear muon capture Muon Decay In Orbit μ-e conversion Andre de Gouvea, W. Molzon, Project-X WS ! 3 CLFV and New Physics E ff ective Lagrangian New Physics contributions Photonic (dipole) term χ 0 ˜ N Photonic 4-fermion µ µ ˜ µ e e l − e W − e �������� H 0 γ q γ γ q q q q q q γ (d) Heavy Neutrinos (e) Exotic Higgs (f) Supersymmetry PRISM < 7 × 10 − 19 4-fermion (contact) term New Physics scale 10 4 µ - N → e - N µ − q µ µ e e COMET Phase II L H 0 Z ′ Br(µ − Al → e − Al) < 7 × 10 − 17 Λ / [TeV] q µ + → e + γ q q q q e − (a) Exotic Higgs (b) Z -prime (c) Leptoquarks COMET Phase I MEG (Final) Br(µ − Al → e − Al) < 7 × 10 − 15 Br(µ − → e − γ ) < 4.2 × 10 − 13 10 3 ✓ Di ff erent measurements are complementary. �������� ✓ µ-e conversion is sensitive to both contributions. SINDRUM II Br(µ − Au → e − Au) < 7 × 10 − 13 We can explore NP scale Excluded beyond 1000 TeV !! Photonic Four-Fermi 10 2 0.01 0.1 1 10 100 κ Photonic 4-fermion

M. Moritsu (KEK) ̶̶ 26/09/2019, J-PARC2019 µ - + (A,Z) → e - + (A,Z) (39% in Al) (61% in Al) ! 4 Muon-to-electron conversion Fate of muonic atom µ-e conversion single mono-energetic electron E μ e = m μ − B μ − E rec = 104.97 MeV for Al Current upper limit SINDRUM-II, EPJ C47, 337 (2006) Br(µ - Au → e - Au) < 7 x 10 -13

! 5 Concept of modern µ -e conversion search Muon Source BG Rejection

M. Moritsu (KEK) ̶̶ 26/09/2019, J-PARC2019 ! 6 Ancestor of COMET/Mu2e October 2011 Yad. Fiz. 49, 622 / Sov. J. Nucl. Phys. 49, 384 ( 1989 ) Vladimir Lobashev 1934–2011 Vladimir Lobashev, who was well known Academy of Sciences, Troitsk, where in the fjeld of nuclear and elementary he played a major role in designing and particle physics, passed away on 3 August, supervising the construction of the complex after a long illness. He made important of intense beams of the Moscow Meson contributions to fundamental studies in Factory. His most signifjcant recent result is parity and CP violation, to neutron and an invention of a new type of spectrometer neutrino physics, and to medium-energy for beta-decay electrons and an experiment physics. to make a direct measurement of the mass of The early part of Lobashev’s scientifjc the electron-neutrino in tritium beta-decay, career, at St Petersburg Nuclear Physics which together with the Mainz experiment Institute of the Russian Academy of produced the best limit on the neutrino Sciences, was dedicated mainly to the mass. weak interaction physics. His discovery Lobashev’s research was highly of parity-violating effects in nuclear appreciated in Russia and all over the world. electromagnetic transitions was instrumental He was a member of the Russian Academy in establishing the universality of weak of Sciences and received many government interactions. He was awarded the Lenin awards, including the title of Honorary Prize for this work in 1974. In the course Citizen of the city of Troitsk. of this research he discovered and made His passing is a great loss to Russian the fjrst measurements of a new effect in science. He will always be remembered by QED � the rotation of the polarization plane his numerous former students and colleagues of gamma-rays in propagating through Vladimir Lobashev. (Image credit: INR.) as a great researcher who devoted all of his MELC@INR, Moscow polarized electrons. He also designed novel life to science. CERN Courier 51, 8 (2011) methods of dealing with ultracold neutrons the best in the world at the time. �e express our deep sorrow to his relatives and obtained a limit on the CP-violating In 1972 Lobashev moved to the Institute and close friends. proposed (1992) neutron electric-dipole moment, which was for Nuclear Research of the Russian ● Friends and colleagues. Mu2e@FNAL 30 years from Ryszard Gokieli, a highly valued gradually increased his commitment to high-energy physicist and computing expert, the CMS experiment, as a member of the MECO@BNL passed away on 20 July, after a two-month �arsaw group. Once again seduced by the First Idea struggle to recover from a serious heart challenges of data processing, he started cancelled attack. developing computing Grids. In 200� he Usually seen late at night in his offjce, became a member of the CERN-led project, with a laptop and a cup of coffee, Gokieli Enabling Grids for E-science, and soon was known to his colleagues and friends as afterwards became the Polish representative COMET@J-PARC a brilliant researcher, unusually competent in the �orldwide LHC Computing Grid and tireless in his work. His friends initiative. Setting up a pan-European and remember talking to him as a pleasure, worldwide grid for high-energy physics enjoying the correctness of his judgements was a major success, but also Gokieli�s and his specifjc, subtle sense of humour. His personal success. Its importance can only younger colleagues will always recall how be appreciated now that the LHC is gaining helpful he was in both physics and computing Ryszard Gokieli. (Image credit: Jerzy impetus and discoveries are round the matters. Noma�czuk.) corner. Born in 1947, Gokieli graduated from the In 2009 Gokieli took on yet another big University of �arsaw. For most of his career providing evidence for the quark nature of task in organizing and building national he was employed by the Soltan Institute hadronic matter. Then, for about 1� years computing infrastructure and services for for Nuclear Studies and was involved in a beginning in late 1980s, he was a member nuclear power plants in Poland. As deputy series of large experiments on the particle of the DELPHI collaboration at the Large director he recently devoted most of his colliders at CERN. In the 1970s he worked Electron�Positron collider. There his enthusiasm to this project � the Computing in the Split Field Magnet Collaboration at competence in computing was recognized Centre �wierk � in work that has now been the Intersecting Storage Rings, where the and he became leader of the DELPHI Central sadly and terminally interrupted. production of hadrons at large transverse Computing effort. ● �o�ciech �i�licki, Soltan Institute for momenta was observed for the fjrst time, �ith the advent of the LHC era, Gokieli Nuclear Studies. 44 CCOct11-Faces.indd 44 06/09/2011 12:3�

M. Moritsu (KEK) ̶̶ 26/09/2019, J-PARC2019 magnetic field B(low) B(high) Vladimir Lobashev 1934-2011 CERN Courier Vol 51, No 8 Pion/muon collection using gradient B • Momentum and charge separation • Same scheme used in COMET Phase-II electron spectrometer Curved Solenoid Beam Transport ! 7 Muon source Powerful muon source is mandatory !! p r Production target o t o n b e a m To achieve 10 -17 sensitivity, Production Target ~10 11 muons/sec (with 10 7 sec running time.) Capture Solenoid ‣ Long production target 5 T Transport Solenoid 3 T ‣ Capture solenoid • Backward generated pion → muon Muon Stopping Target 1 T ‣ Curved Transport solenoid • Vertical drift → Momentum & charge selection Capture solenoid P T Transport solenoid p t Vertical Dipole Magnetic Field Ver$cal(Field � p l P L z High(momentum(track � Beam(collimator � Low(momentum(track � 3 s 4 p 2 L + 1 2 p 2 1 B comp = 1 p 0 1 3 4 T gradient magnetic field D = , cos θ 0 + qB R p L qR 2 cos θ 0 1 3 4 3 of negatively charged particles with mo

M. Moritsu (KEK) ̶̶ 26/09/2019, J-PARC2019 ① ② ③ ! 8 Background rejection Decay-in-orbit → Detector Beam-related prompt BG → Beam Cosmic-ray induced → Veto

M. Moritsu (KEK) ̶̶ 26/09/2019, J-PARC2019 ① Simulation Signal DIO ! 9 Background rejection (1) Decay-in-orbit → Detector resolution Intrinsic physics background Muon decay in orbit � (E - E µ e ) 5 E DIO Log scale Required momentum resolution ∆ p < 200 keV/c for BR~10 -15 E µe < 150 keV/c for BR~10 -17 for 105 MeV/c electrons A.Czarnecki, X.G.i Tormo, W.J.Marciano, PRD 84, 013006 (2011).