WG4 Summary and Future Plans

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


The Muon Trio:• Lepton Flavor Violation

• Muon MDM (g-2) chiral changing

• Muon EDM


MECO

MEG

PRIME


Today with e+e- based theory:

All E821 results were obtained with a “blind” analysis.

world average


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.


Present EDM Limits

Particle Present EDM limit(e-cm)

SM value(e-cm)

n

future exp

10-24 to 10-25

*projected


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)


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


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


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


SUSY connection between a , Dμ , μ → e


aμ sensitivity to SUSY (large tan)


SUSY, dark matter, (g-2)

CMSSM


E969 = now


E969


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


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


The Experiments: LFV

• μe conversion and Muonium-anti-Muonium conversion – pulsed beam

• μ→ e and eee– DC beam


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


MEG @ PSI (10-13 BR sensitivity)

Discovery Potential: 4 Events BR = 2 X 10-13


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


• 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



+ e- → - e+

Muonium productionFull M search


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.


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?


Use an E field for vertical focusing

spin difference frequency = s - c

0


Muon (g-2): Store ± in a storage ring

magnetic field averaged over azumuth in the storage ring


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


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.


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


Where we came from:


Today with e+e- based theory:

All E821 results were obtained with a “blind” analysis.

world average


Muon EDM

• Present limit ~10-19 e-cm• Could reach 10-24 to 10-25 at a high

intensity muon source?


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!


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


Up/Down asymmetry vs. time

time


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


A possible lattice

Yuri Orlov


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


Additional topics:

• Muons for condensed matter (SR)• Muon catalyzed fusion (CF)

• Muon lifetime (GF)

• Muon capture (gp)

• . . .


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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)


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).


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


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


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


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.

Documents

WG4 Summary and Future Plans