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WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 1/48
WG4 Summary and Future Plans
The muon trioand
more
B. Lee RobertsDepartment of Physics
Boston University
[email protected] http://physics.bu.edu/roberts.html
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 2/48
The Muon Trio:• Lepton Flavor Violation
• Muon MDM (g-2) chiral changing
• Muon EDM
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 3/48
MECO
MEG
PRIME
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 4/48
Today with e+e- based theory:
All E821 results were obtained with a “blind” analysis.
world average
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 5/48
Electric and Magnetic Dipole Moments
Transformation properties:
An EDM implies both P and T are violated. An EDM at a measureable level would imply non-standard model CP. The baryon/antibaryon asymmetry in the universe, needs new sources of CP.
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 6/48
Present EDM Limits
Particle Present EDM limit(e-cm)
SM value(e-cm)
n
future exp
10-24 to 10-25
*projected
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 7/48
General Statements
• We know that oscillate– neutral lepton flavor violation
• Expect Charged lepton flavor violation at some level– enhanced if there is new dynamics at the
TeV scale• in particular if there is SUSY
• We expect CP in the lepton sector (EDMs as well as oscillations)– possible connection with cosmology
(leptogenesis)
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 8/48
The Physics Case:
• Scenario 1– LHC finds SUSY– MEG sees → e
• The trio will have SUSY enhancements– to understand the nature of the SUSY
space we need to get all the information possible to understand the nature of this new theory
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 9/48
SUSY pSUSY predictions redictions ofof AA e e--A A
From From BarbieriBarbieri,Hall, ,Hall, Hisano Hisano ……
0 0
MECO single MECO single event event sensitivitysensitivity
10 -11
10 -13
10 -15
10 -19
10 -17
10 -21
PRIME single eventPRIME single eventsensitivitysensitivity
ee & & --AA e e--AA Branching Branching Ratios are linearly correlated Ratios are linearly correlated
300200
eAABR
eBR
100 200 300 100 200 300 Rem (GeV)
Complementary measurementsComplementary measurements (discrimination between SUSY models)(discrimination between SUSY models)
RRee
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 10/48
Experimental Experimental boundbound
Largely favouredLargely favoured and confirmed by and confirmed by KamlandKamland
Additional contributionAdditional contribution toto slepton mixingslepton mixing fromfrom VV2121, matrix element , matrix element responsible responsible forfor solar neutrino deficit solar neutrino deficit. (. (J. Hisano & N. Nomura, Phys. Rev. J. Hisano & N. Nomura, Phys. Rev. D59D59 (1999) (1999) 116005)116005)..
All All solar solar experimentsexperiments combinedcombined
tan(tan() = ) = 3030
tan(tan() = 0) = 0
MEG MEG goalgoal
AfterAfterKamlandKamland
Connection with oscillations
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 11/48
SUSY connection between a , Dμ , μ → e
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 12/48
aμ sensitivity to SUSY (large tan)
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 13/48
SUSY, dark matter, (g-2)
CMSSM
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 14/48
E969 = now
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 15/48
E969
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 16/48
The Physics Case
• Scenario 2– LHC finds Standard Model Higgs at a
reasonable mass, nothing else, (g-2) discrepancy could be the only indication beyond neutrino mass of New Physics
• Then precision measurements come to the forefront, since they are sensitive to heavier virtual particles. – μ-e conversion is especially sensitive to
other new physics besides SUSY
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 17/48
Sensitivity to Various e Conversion Mechanisms
CΛ = 3000 TeV
-4HH μμμeg =10 ×g
Compositeness
Second Higgs doublet
2Z
-17
M = 3000 TeV/c
B(Z μe) <10
Heavy Z’, Anomalous Z coupling
Predictions at 10-15
Supersymmetry
2* -13μN eNU U = 8×10
Heavy Neutrinos
L
2μd ed
M =
3000 λ λ TeV/c
Leptoquarks
After W. Marciano
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 19/48
The Experiments: LFV
• μe conversion and Muonium-anti-Muonium conversion – pulsed beam
• μ→ e and eee– DC beam
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 20/48
Near Term Experiments on LFV
• MEG @ PSI (under construction, data begins in 2006)– 10-13 BR sensitivity
• MECO @BNL (funding not certain)– 10-17 BR sensitivity
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 21/48
MEG @ PSI (10-13 BR sensitivity)
Discovery Potential: 4 Events BR = 2 X 10-13
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 22/48
The MECO ApparatusStraw Tracker
Crystal Calorimeter
Muon Stopping Target
Muon Beam Stop
Superconducting Production Solenoid
(5.0 T – 2.5 T)
Superconducting Detector Solenoid
(2.0 T – 1.0 T)
Superconducting Transport Solenoid
(2.5 T – 2.1 T)
Collimators
10-17 BR single event sensitivity
p beam
approved but not funded
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 23/48
• PRIME-type experiment – with FFAG muon storage ring– few X 10-19
• Such an experiment is perfect for the front end of a muon factory
Future Experiments on LFV
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 24/48
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 25/48
+ e- → - e+
Muonium productionFull M search
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 26/48
An improvement of 102 on GMM
would confront these types of models which would also contribute to double – decay. At the front end of a factory with a pulsed beam this might be possible.
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 27/48
Future Muon (g-2) Experiments
• E969 @ BNL 0.5 → 0.20 ppm (scientific approval but not funded)– expected near-term improvement in
theory, → the ability to confront the SM by ~ x 2
• The next generation 0.20 → 0.06 ppm– substantial R&D would be necessary
• new ring or improved present ring?
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 28/48
Use an E field for vertical focusing
spin difference frequency = s - c
0
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 29/48
Muon (g-2): Store ± in a storage ring
magnetic field averaged over azumuth in the storage ring
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 30/48
E969: Systematic Error Goal
• Field improvements will involve better trolley calibrations, better tracking of the field with time, temperature stability of room, improvements in the hardware
• Precession improvements will involve new scraping scheme, lower thresholds, more complete digitization periods, better energy calibration
Systematic uncertainty (ppm)
1998 1999
2000 2001
E969
Goal
Magnetic field – p 0.5 0.4 0.24 0.17 0.1
Anomalous precession – a
0.8 0.3 0.3 0.21 0.1
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 31/48
SM value dominated by hadronic issues:
• Lowest order hadronic contribution ( ~ 60 ppm)
• Hadronic light-by-light contribution ( ~ 1 ppm)
The error on these two contributions will ultimately limit the interpretation of a more precise muon (g-2) measurement.
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 32/48
A (g-2) experiment to ~0.06 ppm?
• Makes sense if the theory can be improved to 0.1 ppm, which is hard, but maybe not impossible.
• With the present storage ring, we already have
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 33/48
Where we came from:
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 34/48
Today with e+e- based theory:
All E821 results were obtained with a “blind” analysis.
world average
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 35/48
Muon EDM
• Present limit ~10-19 e-cm• Could reach 10-24 to 10-25 at a high
intensity muon source?
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 36/48
Spin Precession Frequencies: in B field with both an MDM and EDM
The EDM causes the spin to precess out of plane.
The motional E - field, β X B, is much stronger than laboratory electric fields . ~GV/m with no sparks!
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 37/48
EDM – up/down Asymmetry• avoid the magic γ and use a radial E-
field to turn off (g-2) precession
• Place detectors above and below the vacuum chamber and look for an up/down asymmetry which builds up with time
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 38/48
Up/Down asymmetry vs. time
time
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 39/48
The EDM ring
• run with both μ+ and μ-.• there must be regions of combined E+B
along with separate focusing elements.• There needs to be a scheme to inject CW
and CCW.
E B p R
2 MV/m
0.25T 0.5 GeV/c
5 11μs 7 m
Possible Muon EDM Ring Parameters
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 40/48
A possible lattice
Yuri Orlov
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 41/48
NP2
• the figure of merit is Nμ times the polarization.
• we need
to reach the 10-24 e-cm level.
Narrow pulsed beam every ~100 s
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 42/48
Additional topics:
• Muons for condensed matter (SR)• Muon catalyzed fusion (CF)
• Muon lifetime (GF)
• Muon capture (gp)
• . . .
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 43/48
0 1 2 3 4 5 6 7 8 9 10
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
Muo
n S
pin
Pol
aris
atio
n
Time (s)
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0.0
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n S
pin
Pol
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atio
n
Time (s)
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-1.0
-0.8
-0.6
-0.4
-0.2
0.0
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1.0
Muo
n S
pin
Pol
aris
atio
n
Time (s)
0 1 2 3 4 5 6 7 8 9 10
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
Muo
n S
pin
Pol
aris
atio
n
Time (s)
B(z)
z0
Superconductor
Magnetic field profile B(z) over nm scale Characteristic lengths of the sc
Depth dependent SR measurements in near surface regions
B(z)
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 44/48
Magnetic Field Profile in YBa2Cu3O7-
0 50 100 150
1E-3
0.01YBa
2Cu
3O
7-, T=20K, Tc=87.5K
hext
= 91.5(3) G,
0 = 1.5 nm fixed,
0 = 137(10) nm
hext
exp(-z/(T)) 3.4 keV 8.9 keV 15.9 keV 20.9 keV 29.4 keV
B (
T)
z (nm)
0 90
local response exponential profile
700
600
500
400
300
200
1000 10 20 30 40 50 60 70 80 90
T h in F ilm (M eissn er s ta te) T h in F ilm (m ixed sta te ) S ing le c rysta l (m ix ed sta te , So n ier e t a l., P R L (199 4) 744 )72
Tem perature [K]
ab(T
) [n
m]
)T(z
0abeB)z(B
Direct test of theories (London, BCS)
)T(nm
)T(s
*
Direct, absolute measurement of magnetic penetration depth
effective mass density of supercarriers
T.J. Jackson, T.M. Riseman, E.M. Forgan, H. Glückler, T. Prokscha, E. Morenzoni, M. Pleines, Ch. Niedermayer, G. Schatz, H. Luetkens, and J. Litterst, Phys. Rev. Lett. 84, 4958 (2000).
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 45/48
Beams needed:
• Pulsed intense muon beams– energy from surface (28 MeV/c) to 3.1
Gev/c
• A few experiments could used DC beam, but almost all can use the pulse structure of a pulse, and somes with no beam
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 46/48
Beam requirements: A few examples
Exp. # p pulse
width
Toff p p/p Pol
→e 102
0
<20 ns 1–100 s ≤28 Mev/c 3% N
(g-2) 101
5
<20 ns 1 ms 3.1 Gev/c 0.5% Y
EDM 101
8
<20 ns 100-500 s 0.3-1.5 Gev/c
~0.1% Y
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 47/48
Plans for next year
• LFV experiments will continue to develop the techniques needed for these challenging experiments
• Muon EDM collaboration will continue to investigate the appropriate ring structure.
• Participate in scoping study for factory– At present muon physics is not mentioned
in the document of 10 June 2005
WG4: physics B. Lee Roberts, on behalf of the Intense Muon Physics Working Group - p. 48/48
Summary
• The questions addressed are at the center of the field of particle physics
• There is an important program of muon physics which will be possible at the front-end of a factory.– It makes use of the very intense flux which will
be available there
• If such a muon facility exists, there will also be a program of other very interesting muon experiments which is possible.