Douglas BrymanUniversity of British Columbia
Seeking New Physics with Rare DecaysEarly Adventures at TRIUMF and Future Prospects
JMP Retirement Symposium 2012
04/21/23 JMP 2
Standard Model : A great story … but definitely not the whole story…Standard Model : A great story …
but definitely not the whole story…
• Cosmological issues: inflation, dark matter, dark energy, matter anti-matter asymmetry…
• Theoretical issues: gravity, neutrino mass, flavor problem, hierarchy problem, divergences .…
+ Higgs
3
COSMOLOGICAL
EVOLUTION, BBN
LEPTOGENESIS?
Rare Decays and Symmetry Violations
LHC: TeV Energy Scale
New Physics
Higher Mass Higher Mass Scales?Scales?
Rare Decays
Neutrino oscillations; CP-/T-violation, edm's...
, ,K, B...
Direct production of new particles
Indirect indication of new particles and effects
4
Light Particle Rare Decay Experiments
Exotic SearchesNew physics if seen; SM effects are negligible.
BSM Physics
New physics if deviations from well-calculated SM predictions occur.
L Ve F
( )
( ) Universality K e
K
10-10: 7 events
<7.8 10-13
<2.4 10-12
10-4: 4x105 events
0 0 violationL
K
K CP
LFN Ve N
Early TRIUMF Experiments – Still being pursued today!
<2.6 10-8
1977
TRIUMF
1986
1983,1994
1983 2004
State of the Art
Jean-Michel and Renee were important contributors to many experiments.
Seeking Answers with Rare Decays
Cartoon from Jewish Daily Forward (1920’s)
Not exactly the mainstream
6
Lepton Flavor Violation
Lepton Flavor Violation
e
e e
W
e0
e
SM
604
4B 10R( )
W
em
m
SUSYBR( )e
4
5 2
SUS2
Y
2100 GeV
10 tanem
mm
≈ 10-13
• Observation means new physics.• Some SUSY models predict BR(→ e) near the
experimental limit ~10-12.
• Observation means new physics.• Some SUSY models predict BR(→ e) near the
experimental limit ~10-12.
SMSM SUSYSUSY
H4H
1Sensitivity to new physics ~ with M ~ 1 100 TeV
M
ee Muon Decay
e
e
04/21/23 7
History of Some Rare Decay ExperimentsHistory of Some Rare Decay ExperimentsLepton Flavor Violation
90% CL
Future: Many new
experiments coming.
From Marciano, Mori, Roney 2010
D.B. Thesis
TRIUMF TPC… (1987)
TRIUMF µ->eγ
1977
TINA+MINA
Hincks, Pontecorvo
J.M. Poutissou,
D. Measday et al.
e (1974)
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• 107 – 108 /sec, 100% duty factor• LXe for efficient detection• Solenoidal magnetic spectrometer
• 107 – 108 /sec, 100% duty factor• LXe for efficient detection• Solenoidal magnetic spectrometer
MEG Experiment at PSI
S. Ritt
Goal B<1.310-13 (0.01 x prev. exp) e
Current result (2009-2010) data B <2.410-12 (90% c.l.)
JPARC: DeeMee Aoki et al.
04/21/23 Doug Bryman JMP Symposium 9
100 /MeV c
14at <10 N e N
10
16at 10 N e N
BNL MECO 2
e Conversion at Fermilab
Mu E
at JPARC
Kuno et al.
COMET
• Singles experiment mitigates high rates.• Background (decay-in-orbit) known and calculable.• High resolution detector feasible.• Possible improvement x 104
Lobashov (1980): Solenoid Pion Collector; flux x 1000.
Proposals:
Lepton Universality & e , , have identical electroweak gauge
interactions: differ only in mass and coupli
Standard M
ng to Higg
odel:
s on.
bos
e
,e
S=0
e J=0
e ...Unless new physics does not respect universality.g =g
Universality Testse
410 Helicity Suppression
-Leptoquarks-Excited gauge bosons-Compositeness-SU(2)xSU(2)xSU(2)xU(1)-Lepton Flavor Violation-Extra dimensions…-Heavy neutrinos
R-parity violating SUSYOthers
Marciano…
Ramsey-Musolf…
2H
1New Physics e.g. pseudoscalars in ~
M?e
exp/0.1 % measurement of R 1000 TeVe H
M
H e
Non-standard Higgs couplings
04/21/23 JMP Symposium 13
TRIUMF 1
PSI 1TRIUMF 2
PIENU (TRIUMF 3) PEN (PSI 2)Goals (±0.05%)
4/R =1.2353 1 10 (±0.008%) th
e x
W. Marciano V. Cirigliano (2007)
Theory (±0.008%)
(±0.33%)
Branching Ratioe
Experiments
14
e+
Precision goal: <0.05%
• Large solid angle (x10)Large solid angle (x10)– More statistics – Lower energy dependent acceptance difference– Detect shower leakage (CsI) for low energy tail – measurement (biggest systematics)
• Silicon Strips & WC TrackingSilicon Strips & WC Tracking– Much improved tracking– Detect Decay-In-Flight for tail correction
• High resolution calorimeterHigh resolution calorimeter– BINA resolution 2 times better than TINA
• Use of 500 MHz fast digitizersUse of 500 MHz fast digitizers– Good separation between ->eν and ->µ->e
beam
50 cm
04/21/23 JMP Symposium 15
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Photonuclear Effects in NaI(Tl) Detectors
A positron beam was injected into the NaI(Tl)
Extra structure (bumps) were observed – simulation confirms that multiple neutron emission is responsible.
Simulations:With PhotonuclearSans Photonuclear
Data
04/21/23 17
Energy Spectrum
5Suppress 10 to reveal the NaI low energy taile
Current Estimate:
Tail Fraction
(2.03 0.28)%
PIENU Time DATA and Fits
Low Energy High Energy
Expected Error Budget:
04/21/23 19
Summary: Rare Decays
-e Conversion: DeeMee, COMET (JPARC), Mu2E (Fermilab)
* Future experiments have great potential:
ORKA Project X (Fermila (Fermil bab): ) ; K
* , , and K decays continue to challenge the Standard Model
* Current experiments have great sensit
MEG ( ), PIENU and PEN ( ,
NA6
ivity to possible new physics
2 ,
:
e )PSI TRIUMF PSI
CERN JPA
e
K
30 0 KOTO & TREK( )LRC KK
For more than two decades Jean-Michel and Renee Poutissou made many important contributions to successful TRIUMF experiments searching for and measuring rare decay processes.
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