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TRANSCRIPT
Muon Experiments in Project X
Yoshitaka KunoDepartment of PhysicsOsaka University
DOE BriefingNovember 17th, 2010
1
Outline
•Why Intensity Frontier with Muons?•Project X Muon Source: Comparison in the World•Muon Experiments at Project X•Why Charged Lepton Flavor Violation (CLFV) ?•Why μ-e Conversion, not μ→eγ ?•Why 10-18 for µ-e Conversion ?•Planned µ-e Conversion Experiment at Fermilab (Mu2e)•µ-e Conversion Experiment at Project X•Summary
2
Why Intensity Frontierwith Muons ?
3
10-10sec
10-34sec
102GeV
1016GeV
1019GeV
102sec
1013sec
10-3GeV
10-9GeV
timescale
energy scale
Quantum Gravity Epoch
Superstrings
Electroweak Epoch
Origin of Mass (Higgs Particle)
New Symmetry (Supersymmetry)
Unification Epoch
Unification of Fundamental Forces(GUT)
Origin of Neutrino mass(Right-handed Neutrinos)
Our Existence in the Universe(Leptogenesis)
4
1016 GeV is important.
10-10sec
10-34sec
102GeV
1016GeV
1019GeV
102sec
1013sec
10-3GeV
10-9GeV
timescale
energy scale
Quantum Gravity Epoch
Superstrings
Electroweak Epoch
Origin of Mass (Higgs Particle)
New Symmetry (Supersymmetry)
Unification Epoch
Unification of Fundamental Forces(GUT)
Origin of Neutrino mass(Right-handed Neutrinos)
Our Existence in the Universe(Leptogenesis)
5
The Intensity Frontier is.....
• Energy scale reached by the intensity frontier would be much higher than that of accelerators of O(1 TeV) through quantum radiative corrections (renormalization group equation = RGE).
• Effects are small.• Rare process searches• High precision measurements
• High intensity machine is needed.• Indirect searches
Quantum Corrections
∆E ∼ �2∆t
Uncertainty principle
6
Why Muons for the Intensity Frontier ?
Guidelines for Rare Process Searches
(1) Many particles are needed
The muon is the lightest unstable particle and therefore given energy, more muons can be produced.
(2) Theoretical uncertainty should be small.
The muon does not have strong interaction, and therefore the processes with muons are theoretically clean.
7
Project X Muon Source:Comparison
8
Comparison : Muon Beam Sources
beam power time structure muon yield
PSI 1.2 MW DC 108/sec
TRIUMF 75 kW DC 105/sec
MuSIC 400 W DC 107-8/sec
RAL 200 kW pulsed (50 Hz) 2x105/sec
J-PARC (MLF) 1 MW pulsed (25 Hz) 2x107/sec
Project X Muon 1-2 MW DC & pulsed 108-12/sec
9
Comparison : Muon Beam Sources
beam power time structure muon yield
PSI 1.2 MW DC 108/sec
TRIUMF 75 kW DC 105/sec
MuSIC 400 W DC 107-8/sec
RAL 200 kW pulsed (50 Hz) 2x105/sec
J-PARC (MLF) 1 MW pulsed (25 Hz) 2x107/sec
Project X Muon 1-2 MW DC & pulsed 108-12/sec
adjustable10
Comparison : Muon Beam Sources
beam power time structure muon yield
PSI 1.2 MW DC 108/sec
TRIUMF 75 kW DC 105/sec
MuSIC 400 W DC 107-8/sec
RAL 200 kW pulsed (50 Hz) 2x105/sec
J-PARC (MLF) 1 MW pulsed (25 Hz) 2x107/sec
Project X Muon 1-2 MW DC & pulsed 108-12/secCapability of pulsed muon beams would
make “Muons at Project X” unique.
adjustable11
Muon Experimentsat Project X
12
Muon Particle Physics Programs at Project X
Mode BeamCurrent
limitplanned
goalProject X
goal Priority
µ-N→e-N pulsed <10-12 3x10-17 3x10-19
µ+→e+γ DC <1.1x10-12 2x10-13 2x10-14
µ*→e+e+e- DC <10-12 - 1x10-16
µ-e-N→e-e-N DC - 1x10-16
Mu to Mu conv pulsed <8x10-11 <5x10-15
muon EDM pulsed <1.8x10-19 <5x10-25
muon lifetime pulsed 1ppm 0.1ppm
13
Muon Particle Physics Programs at Project X
Mode BeamCurrent
limitplanned
goalProject X
goal Priority
µ-N→e-N pulsed <10-12 3x10-17 3x10-19
µ+→e+γ DC <1.1x10-12 2x10-13 2x10-14
µ*→e+e+e- DC <10-12 - 1x10-16
µ-e-N→e-e-N DC - 1x10-16
Mu to Mu conv pulsed <8x10-11 <5x10-15
muon EDM pulsed <1.8x10-19 <5x10-25
muon lifetime pulsed 1ppm 0.1ppm
14
Muon Particle Physics Programs at Project X
Mode BeamCurrent
limitplanned
goalProject X
goal Priority
µ-N→e-N pulsed <10-12 3x10-17 3x10-19
µ+→e+γ DC <1.1x10-12 2x10-13 2x10-14
µ*→e+e+e- DC <10-12 - 1x10-16
µ-e-N→e-e-N DC - 1x10-16
Mu to Mu conv pulsed <8x10-11 <5x10-15
muon EDM pulsed <1.8x10-19 <5x10-25
muon lifetime pulsed 1ppm 0.1ppmµ-e conversion is a flagship experiment.
15
Why CLFV ?
16
What is Charged Lepton Flavor Violation ?
Quark mixingobserved
Quarks
17
What is Charged Lepton Flavor Violation ?
Quark mixingobserved
Quarks
Leptons
荷電レプトン混合現象
Neutrino mixingobserved
18
What is Charged Lepton Flavor Violation ?
Quark mixingobserved
Quarks
Leptons
荷電レプトン混合現象
Neutrino mixingobserved
Charged lepton mixing not observed.
Nobel Prize-wining class researchCharged Lepton Flavor Violation (CLFV)
19
cLFV in the SM with massive neutrinos
B(µ→ eγ) =3α
32π
����
l
(VMNS)∗µl(VMNS)el
m2νl
M2W
���2
Note: LFV in SM with massive neutrinos
µ e
γ
ν very tiny!
The SM with neutrino masses predicts small event rates for the LFV.
W
The observation of the LFV will be clearly a discovery of physics beyond the SM with non-zero neutrino masses.
BR(µ→ eγ) ∝ (δm2ν)2 < 10−54
5
BR~O(10-54)
Observation of CLFV would indicate a clear signal of physics beyond the SM with massive neutrinos.
20
Comparison of Sensitivity to New Physics Models (a la Prof. Dr. A. Buras at TUM)
AC RVV2 AKM δLL FBMSSM LHT RS
D0 − D0 ��� � � � � ��� ?
�K � ��� ��� � � �� ���Sψφ ��� ��� ��� � � ��� ���
SφKS ��� �� � ��� ��� � ?
ACP (B → Xsγ) � � � ��� ��� � ?
A7,8(B → K∗µ+µ−) � � � ��� ��� �� ?
A9(B → K∗µ+µ−) � � � � � � ?
B → K(∗)νν � � � � � � �Bs → µ+µ− ��� ��� ��� ��� ��� � �K+ → π+νν � � � � � ��� ���KL → π0νν � � � � � ��� ���µ → eγ ��� ��� ��� ��� ��� ��� ���τ → µγ ��� ��� � ��� ��� ��� ���µ+N → e+N ��� ��� ��� ��� ��� ��� ���
dn ��� ��� ��� �� ��� � ���de ��� ��� �� � ��� � ���(g − 2)µ ��� ��� �� ��� ��� � ?
Table 8: “DNA” of flavour physics effects for the most interesting observables in a selection of SUSYand non-SUSY models ��� signals large effects, �� visible but small effects and � implies thatthe given model does not predict sizable effects in that observable.
• vanishingly small effects (one black star).
This table can be considered as the collection of the DNA’s for various models. These DNA’s
will be modified as new experimental data will be availabe and in certain cases we will be
able to declare certain models to be disfavoured or even ruled out.
In constructing the table we did not take into account possible correlations among the
observables listed there. We have seen that in some models, it is not possible to obtain
large effects simultaneously for certain pairs or sets of observables and consequently future
measurements of a few observables considered in tab. 8 will have an impact on the patterns
shown in this DNA table. It will be interesting to monitor the changes in this table when the
future experiments will provide new results.
65
Different theoretical models
W. Altmannshofer, A.J. Buras, S. Gori, P. Paradisi, D.M. Straub, . Nucl.Phys.B830:17-94,2010.
21
Comparison of Sensitivity to New Physics Models (a la Prof. Dr. A. Buras)
AC RVV2 AKM δLL FBMSSM LHT RS
D0 − D0 ��� � � � � ��� ?
�K � ��� ��� � � �� ���Sψφ ��� ��� ��� � � ��� ���
SφKS ��� �� � ��� ��� � ?
ACP (B → Xsγ) � � � ��� ��� � ?
A7,8(B → K∗µ+µ−) � � � ��� ��� �� ?
A9(B → K∗µ+µ−) � � � � � � ?
B → K(∗)νν � � � � � � �Bs → µ+µ− ��� ��� ��� ��� ��� � �K+ → π+νν � � � � � ��� ���KL → π0νν � � � � � ��� ���µ → eγ ��� ��� ��� ��� ��� ��� ���τ → µγ ��� ��� � ��� ��� ��� ���µ+N → e+N ��� ��� ��� ��� ��� ��� ���
dn ��� ��� ��� �� ��� � ���de ��� ��� �� � ��� � ���(g − 2)µ ��� ��� �� ��� ��� � ?
Table 8: “DNA” of flavour physics effects for the most interesting observables in a selection of SUSYand non-SUSY models ��� signals large effects, �� visible but small effects and � implies thatthe given model does not predict sizable effects in that observable.
• vanishingly small effects (one black star).
This table can be considered as the collection of the DNA’s for various models. These DNA’s
will be modified as new experimental data will be availabe and in certain cases we will be
able to declare certain models to be disfavoured or even ruled out.
In constructing the table we did not take into account possible correlations among the
observables listed there. We have seen that in some models, it is not possible to obtain
large effects simultaneously for certain pairs or sets of observables and consequently future
measurements of a few observables considered in tab. 8 will have an impact on the patterns
shown in this DNA table. It will be interesting to monitor the changes in this table when the
future experiments will provide new results.
65
Different theoretical models
W. Altmannshofer, A.J. Buras, S. Gori, P. Paradisi, D.M. Straub, . Nucl.Phys.B830:17-94,2010.
All three stars for µ-e conversion
22
! anomaly in muon g-2 (?)
Hagiwara et al: hep-ph/0611102
W
νµ
µ
γ
νe
e
µ→ eγ
6
µ+! e
+!
an example diagram
CLFV in SUSY Models
Since neutrinos are mixed & LFC is violated, sleptons can mix.
! anomaly in muon g-2 (?)
Hagiwara et al: hep-ph/0611102
H
νR
The LFV search can study the physics here even if we can not directly produce the heavy particle ( ) at LHC
νµ νe
6
Slepton Mixing
• neutrino interaction violates lepton flavor number conservation to explain neutrino oscillation
SUSY flavor problem
Since sleptons have new source of flavor violation in their mass matrices, lepton flavor violating
phenomena can be generated by SUSY particles.
There is no symmetry to guarantee the small violation, but the LFV in the slepton masses should be small.
BR(µ→ eγ) � 1× 10−11
�150 GeVmSUSY
�4 �tanβ
20
�2 �∆21
3× 10−4
�2
15
•Through quantum corrections (RGE), slepton mixing is sensitive to physics at very high energy scale (such as GUT and neutrino seesaw models).
•In contrast to proton decay (~1M tons) and double beta decays (~0.1-1 ton), CLFV need only 1019-21 muons.
23
! anomaly in muon g-2 (?)
Hagiwara et al: hep-ph/0611102
W
νµ
µ
γ
νe
e
µ→ eγ
6
µ+! e
+!
an example diagram
CLFV in SUSY Models
Since neutrinos are mixed & LFC is violated, sleptons can mix.
! anomaly in muon g-2 (?)
Hagiwara et al: hep-ph/0611102
H
νR
The LFV search can study the physics here even if we can not directly produce the heavy particle ( ) at LHC
νµ νe
6
Slepton Mixing
• neutrino interaction violates lepton flavor number conservation to explain neutrino oscillation
SUSY flavor problem
Since sleptons have new source of flavor violation in their mass matrices, lepton flavor violating
phenomena can be generated by SUSY particles.
There is no symmetry to guarantee the small violation, but the LFV in the slepton masses should be small.
BR(µ→ eγ) � 1× 10−11
�150 GeVmSUSY
�4 �tanβ
20
�2 �∆21
3× 10−4
�2
15
• neutrino interaction violates lepton flavor number conservation to explain neutrino oscillation
SUSY flavor problem
Since sleptons have new source of flavor violation in their mass matrices, lepton flavor violating
phenomena can be generated by SUSY particles.
There is no symmetry to guarantee the small violation, but the LFV in the slepton masses should be small.
BR(µ→ eγ) � 1× 10−11
�150 GeVmSUSY
�4 �tanβ
20
�2 �∆21
3× 10−4
�2
15
•By using SUSY, CLFV can provide hints of physics at very high energy scale that accelerator cannot directly reach.
•SUSY plays a role of a bridge between physics at high (1016 GeV) and low energy (102 GeV) scales.
24
Why μ-e Conversion,not μ→eγ ?
25
103
104
10-2
10-1
1 10 102
!
" (
TeV
)B(!# e$)"10
-13
B(!# e$)"10-14
B(!# e conv in 48
Ti)"10-16
B(!# e conv in 48
Ti)"10-18
EXCLUDED
Physics Sensitivity Comparison between μ→eγ and μ-e Conversion
photonic(dipole)
non-photonic
μ→eγ yes (on-shell)
no
μ-e conversion
yes (off-shell)
yes
Photonic (dipole) and non-photonic contributions
more sensitive to new physics
26
Experimental Comparison between μ→eγ and μ-e Conversion
• μ→eγ : • Accidental background is given by (rate)2. • The detector resolutions have to be improved, but difficult.• The ultimate sensitivity would be about 10-14.
• μ-e conversion : • A higher beam intensity can be taken because of no accidentals. • Improvement of a muon beam can be possible.
• high intensity and high purity
background challenge beam intensity
• μ→eγ accidentals detector resolution limited
• μ-e conversion beam beam background no limitation
μ-e conversion might be a next step.
27
Why <10-18 Sensitivityfor µ-e conversion ?
28
μ-e Conversion : Target dependence
R. Kitano, M. Koike and Y. Okada, Phys. Rev. D66, 096002 (2002)
0
0.5
1
1.5
2
2.5
0 10 20 30 40 50 60 70 80 90 100
B!N!eN"Z#
/ B!N!eN"Z=$%#
Z
dipole
scalar
vector
normalized at Al
If signal is seen at 10-16,
By changing muon-stopping target materials, effective interaction of new physics can be discriminated.
29
BR~10-19
BR~10-12
Andre de Gouvea Northwestern
1e-07
1e-06
1e-05
1e-04
0.001
0.01
0.1
1
10
100
1000
0 200 400 600 800 1000 1200 1400 1600
y
x
title10
Now
PRIME
CKMMNS
M1/2(GeV)
B(µTi→ eTi)× 1012 tan β = 10
µ→ e conversion is at least as sensitive as µ→ eγ
SO(10) inspired model.
remember B scales with y2.
B(µ→ eγ) ∝M2R[ln(MPl/MR)]2
[Calibbi, Faccia, Masiero, Vempati, hep-ph/0605139]
October 14, 2009 CLFV
Andre
de
Gouvea
Northw
estern
1e-
07
1e-
06
1e-
05
1e-
04
0.0
01
0.0
1
0.1 1 10
100
100
0
0 2
00 4
00 6
00 8
00 1
000
120
0 1
400
160
0
y
x
title
10
Now
PRIM
E
CKM
MN
S
M1/2(G
eV)
B(µ
Ti→
eTi)×
1012
tan
β=
10
µ→
eco
nver
sion
isat
leas
tas
sens
itiv
eas
µ→
eγ S
O(1
0)in
spir
edm
odel
.
rem
ember
Bsc
ales
wit
hy2.
B(µ→
eγ)∝
M2 R[ln(M
Pl/
MR
)]2
[Calibbi,
Facc
ia,M
asi
ero,Vem
pati
,hep
-ph/0605139]
October
14,2009
CLFV
12010年11月16日火曜日
Andre de Gouvea Northwestern
1e-07
1e-06
1e-05
1e-04
0.001
0.01
0.1
1
10
100
1000
0 200 400 600 800 1000 1200 1400 1600
y
x
title10
Now
PRIME
CKMMNS
M1/2(GeV)
B(µTi→ eTi)× 1012 tan β = 10
µ→ e conversion is at least as sensitive as µ→ eγ
SO(10) inspired model.
remember B scales with y2.
B(µ→ eγ) ∝M2R[ln(MPl/MR)]2
[Calibbi, Faccia, Masiero, Vempati, hep-ph/0605139]
October 14, 2009 CLFV
Andre
de
Gouvea
Northw
estern
1e-
07
1e-
06
1e-
05
1e-
04
0.0
01
0.0
1
0.1 1 10
100
100
0
0 2
00 4
00 6
00 8
00 1
000
120
0 1
400
160
0
yx
title
10
Now
PRIM
E
CKM
MNS
M1/2(G
eV)
B(µ
Ti→
eTi)×
1012
tan
β=
10
µ→
eco
nver
sion
isat
leas
tas
sens
itiv
eas
µ→
eγ S
O(1
0)in
spir
edm
odel
.
rem
ember
Bsc
ales
wit
hy2.
B(µ→
eγ)∝
M2 R[ln(M
Pl/
MR
)]2
[Calibbi,
Facc
ia,M
asi
ero,Vem
pati
,hep
-ph/0605139]
October
14,2009
CLFV
12010年11月16日火曜日
12010年11月16日火曜日
PRISM/Project X
2010年11月16日火曜日
Aiming at Single Event Sensitivity of 2x10-19
BR~10-19 covers the whole SUSY-parameter space for LHC. When SUSY is found at LHC, CLFV should be observed.
Calibbi, Faccia, Masiero, Vempati, hep-ph/0605139]
If signal is not seen at 10-16,
Project X
SUSY predictions
30
Sensitivity of <10-18
mSUGRA with right-handed neutrinos
will be improved by a factor of
10,000.
B(µ! + Al ! e! + Al) < 10!16
µ<0,µ<0,
Bran
ching
Rati
os ( µ→
e ; T
i)
10-11
10-12
10-13
10-14
10-15
10-16
10-17
10-18
10-19
Bran
ching
Rati
os ( µ→
e !)
10-9
10-10
10-11
10-12
10-13
10-14
10-15
10-16
0 1.0 2.0 3.00.5 1.5 2.5m" (TeV)
>µ>µµ > ,µ >µ >µ >
LHC
reach
MEG (µ→e!)
This Experiment (µ→e;Al)
Current Exp. Bound on µ→e ; Ti (SINDRUM II)
Mu2e
31
Sensitivity of <10-18
mSUGRA with right-handed neutrinos
will be improved by a factor of
10,000.
B(µ! + Al ! e! + Al) < 10!16
µ<0,µ<0,
Bran
ching
Rati
os ( µ→
e ; T
i)
10-11
10-12
10-13
10-14
10-15
10-16
10-17
10-18
10-19
Bran
ching
Rati
os ( µ→
e !)
10-9
10-10
10-11
10-12
10-13
10-14
10-15
10-16
0 1.0 2.0 3.00.5 1.5 2.5m" (TeV)
>µ>µµ > ,µ >µ >µ >
LHC
reach
MEG (µ→e!)
This Experiment (µ→e;Al)
Current Exp. Bound on µ→e ; Ti (SINDRUM II)
will be improved by a factor of
1000,000.
B(µ! + Ti ! e! + Ti) < 10!18
Project X
Mu2e
32
Sensitivity of <10-18
mSUGRA with right-handed neutrinos
will be improved by a factor of
10,000.
B(µ! + Al ! e! + Al) < 10!16
µ<0,µ<0,
Bran
ching
Rati
os ( µ→
e ; T
i)
10-11
10-12
10-13
10-14
10-15
10-16
10-17
10-18
10-19
Bran
ching
Rati
os ( µ→
e !)
10-9
10-10
10-11
10-12
10-13
10-14
10-15
10-16
0 1.0 2.0 3.00.5 1.5 2.5m" (TeV)
>µ>µµ > ,µ >µ >µ >
LHC
reach
MEG (µ→e!)
This Experiment (µ→e;Al)
Current Exp. Bound on µ→e ; Ti (SINDRUM II)
will be improved by a factor of
1000,000.
B(µ! + Ti ! e! + Ti) < 10!18
Project X
Mu2e
sensitive to multi TeV energy scale.
33
Planned µ-e conversionExperiment (Mu2e)
34
Mu2e at Fermilab(for single event sensitivity of 3x10-17)
!"#$%&'(#)*+#,-)#($*
."/)01#"'*+#,-)#($*+-,-&'0*,#2*
3#3-)'%3*45#($0*0'"/(67'*,()-*8"#3*1"#$%&'(#)*'/"6-'*'#*$-'-&'#"0*
9-'-&'#"*+#,-)#($*
!"#'#)*./"6-'*
./"6-'*+7(-,$()6*
:%#)*;-/3*<#,,(3/'#"0*
."/&=-"*
</,#"(3-'-"*
!(#)0* >,-&'"#)0*:%#)0*
:%#)**+'#11()6*./"6-'*
:%?-*:%#)*;-/3,()-!:%#)0*/"-*&#,,-&'-$@*'"/)01#"'-$@*/)$**$-'-&'-$*()*0%1-"&#)$%&'()6*0#,-)#($/,*3/6)-'0*
9-,(5-"0*ABAA?C*0'#11-$*3%#)0*1-"*D*E-F*1"#'#)*
!"#'#)*;-/3*
D*
;GC*.*
;GH*.*
;G?*.*;G?BC*.*
;GH*.*
35
Muon Intensity for Mu2e
To achieve a single sensitivity of 10-17, we need
1011 muons/sec (with 107 sec running)
whereas the current highest intensity is 108/sec at PSI.
Pion Capture by Superconducting Solenoid System
Guide !’s until decay to !’s
Suppress high"P particles
•!’s : p!< 75 MeV/c
•e’s : pe < 100 MeV/c
only 20 kW beam power needed
36
Background Rejection Methods for Mu2e
Muon DIO background
low-mass trackers in vacuum & thin target
improveelectron energy resolution
curved solenoids for momentum selection
Muon DIFbackground
eliminate energetic muons (>75 MeV/c)
Beam-related backgrounds
Beam pulsing with separation of 1μsec
measured between beam pulses
proton extinction = #protons between pulses/#protons in a pulse < 10-9
37
µ-e ConversionExperimentat Project X
38
Muon Intensityfor Sensitivity < 3x10-19 at Project X
To achieve a single sensitivity of 10-19, we need
>1012 muons/sec (with 107 sec running)
whereas the current highest intensity is 108/sec at PSI.
Pion Capture by Superconducting Solenoid System
Guide !’s until decay to !’s
Suppress high"P particles
•!’s : p!< 75 MeV/c
•e’s : pe < 100 MeV/c
39
Muon Intensityfor Sensitivity < 3x10-19 at Project X
To achieve a single sensitivity of 10-19, we need
>1012 muons/sec (with 107 sec running)
whereas the current highest intensity is 108/sec at PSI.
Pion Capture by Superconducting Solenoid System
Guide !’s until decay to !’s
Suppress high"P particles
•!’s : p!< 75 MeV/c
•e’s : pe < 100 MeV/c
Multi MW beam power at Project X
needed
40
Additional Background Rejection Methodsfor Sensitivity < 3x10-19 at Project X
Muon DIObackground
narrow muon beam spread
1/10 thickness muon stopping target
mono-energetic muon beam
Pionbackground
long muon beam-line long solenoid or a muon storage ring
pion free beam
beam handling technique
developed for muon collider and Nufact.
phase rotation
muon beam cooling
oroptions
41
Phase Rotation Option: PRISM/Project X
PRISMbeamline
PRISM-FFAGmuon storage ring
momentum slit
extract kickers
injection kickers
matching section
curved solenoid (short)
SC solenoid /pulsed horns
PRIME detector
42
Muon Beam Cooling Option: Geant4 Simulation of Ionization Cooling
z = 0, Rinner = 7.5 cm
Bz = 10 T
z = 2 m, Rinner = 12 cm
Bz = 4 T
P(3 GeV)
π – µ –
νµ
43
13
muonic atom becomes shorter as the atomic number increases, from 864 nsec in Al to 79 nsec in Au. In the next-generation experiments like Mu2e and COMET, to remove the prompt beam-related backgrounds, in particular from pions, the time window of measurements starts about 700 nsec after the beam prompt. Therefore, the choice of target materials is currently constrained to light materials. To have a heavy material with a large atomic number, a pion-free beam is needed. And that can be done only at Project-X. 5.1 Sensitivity and Backgrounds
Muon Storage Ring Option!In the case of the muon storage ring proposal, an improvement factor of the signal sensitivity of 100 would come from an increase of the number of muons stopped in the muon-stopping target of a factor of 20, and that of the signal acceptance of more than 5. The latter factor is attributed to the wider time window of measurements (from time zero) and the better momentum acceptance of the measurement, etc. as shown in Table 1.
Table 2 shows a preliminary estimation of a net background event rate, which is about less than 0.1 at a sensitivity of better than 10-18, although detailed simulation are needed.
Table 1. Expected improvement factors for the signal acceptance
Item Improvement factor
Comments
Measurement time window X 2.5 (for Al) No pions in a beam No muon beam stop X 1.7 Narrow beam energy width
Measurement momentum window X1.3 Thinner target thickness Total X 5.6
Table 2. preliminary estimation of background events at a sensitivity of 10-18
Item rate Comments Muon decay in orbit 0.05 350 keV (FWHM) resolution
Radiative muon capture 0.01 Pion related backgrounds ~0 No pions
Muon decay in flight ~0 Momentum cut at extraction Cosmic rays 0.002
Total 0.06
Sensitivity and Backgrounds
2010年11月15日月曜日
Sensitivity and Background (preliminary) at Project X
Sensitivity
Background estimation
• muon beam intensity = 2x1012/sec• detector acceptance = 0.2 • single event sensitivity = 2x10-19
• 90% C.L. upper limit = 5x10-19
44
Muon Particle Physics Programs at Project X
Mode BeamCurrent
limitplanned
goalProject X
goal Priority
µ-N→e-N pulsed <10-12 3x10-17 3x10-19
µ+→e+γ DC <1.1x10-12 2x10-13 2x10-14
µ*→e+e+e- DC <10-12 - 1x10-16
µ-e-N→e-e-N DC - 1x10-16
Mu to Mu conv pulsed <8x10-11 <5x10-15
muon EDM pulsed <1.8x10-19 <5x10-25
muon lifetime pulsed 1ppm 0.1ppm
45
Muon Particle Physics Programs at Project X
Mode BeamCurrent
limitplanned
goalProject X
goal Priority
µ-N→e-N pulsed <10-12 3x10-17 3x10-19
µ+→e+γ DC <1.1x10-12 2x10-13 2x10-14
µ*→e+e+e- DC <10-12 - 1x10-16
µ-e-N→e-e-N DC - 1x10-16
Mu to Mu conv pulsed <8x10-11 <5x10-15
muon EDM pulsed <1.8x10-19 <5x10-25
muon lifetime pulsed 1ppm 0.1ppmRich muon physics programs at Project X
46
Summary
•Physics motivation of CLFV processes would be significant and robust at the LHC era. The CLFV would have sensitivity to study physics at high energy scale, in particular with SUSY,
•Among various muon programs at Project X, μ-e conversion would be a flagship experiment. The aimed single event sensitivity is 2x10-19.
•µ-e conversion experiment needs a pulsed muon beam of 1-2 MW. Project X would provide such a beam, but PSI cannot.
•Muon fundamental physics programs at Project X is rich and would have high discovery potentials.
47
Backup Slides
48
Various Models Predict Charged Lepton Mixing.
49
! !
!!"#$%&'()*+,-).,&/!*.(+/-
"#$%&'()'*!+%$,%--./0$,&01!12,3-
#4%5(36!7-3'(1%$6!839&)3--2
CLFV Predictions byExtra Dimension Models
50
! !
!!"#$$%&!'#(()!*+,&%)!-.#$/!01234#$56
"#$%&'!'(!$#)
*+,,-,!#'.(-%!/$00'0!1'(2''%!344!5'678)9!:'65'%',+;!$%<#'0!$%=!.>$0'0
CLFV Predictions by Little Higgs Model (with T parity)
51
! !
"#$%&&!'()*!+,-!$.&
!"#$%&'"()*$+,-%.)/**/#01)
'")$/20-(/"/1'1
/0*!#1"2-(++2
/334"5+12-36!!72!8,-8(99,+12-3!!!:1(;,;8:18,9!-(4+;1-2!<4=,>,!(1?(-@,94(36!A
.!A
%!A
B
CD(5+2?(-(313!;(E41;(3!"F.&.G!'()*!32!-2!-((H!+2!,334"(!,!9,;?(!84+I2JJK!!
!"#$%&'()*)+(,-./#'-&-0%0(1%/2(345SUSY Leptogenesis with CLFV (1)
52
! !
µ!"#$%&'"()*%&#+,#!"#!$--
"#$%&'(')*+,!-.*/!0%$'*1%+%,),!"
2-*.!/34566!7%89!'(+!4:6;
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A'B$)&(0C!-0(=*>.!%--%&',?!@!5$:6!"%
A%#'.%/%C!-0(=*>.!%--%&',?!@!5$:6!&'
<('>.(0!.%1)*+!-*.!/:?
<*'%!'D('!)+!E%.)=)+1!'D),!.%,>0'!F%!D(=%!(,,>/%E!'D%!F*.,'!&(,%!
,&%+(.)*!-*.!'D%!E%'%&')*+!*-!µ!G!%!-0(=*>.!=)*0(')*+?!!@H$(.)'B!&*+,%.=%EI
!!J+)=%.,(0!,*-'!'%./,!('!'D%!&>'H*--!,&(0%I
!!K>L(F(!'%#'>.%,!'D('!/)+)/)M%!'D%!-0(=*>.!=)*0(')*+?"2K(
"
!K
(;!E)(1*+(0I"
!!N0,*9!)'!),!>+0)L%0B!'D('!O:!,('>.('%,!'D%!0*F%.!P*>+E!2'D),!.%Q>).%,!*$')/(0!RS!$D(,%,;I
)
%!"#!$%#%&'()!*+,-!('&$%&!&'.%/!%01%,.%2
SUSY Leptogenesis with CLFV (2)
53
SUSY Predictions for cLFV
SU(5) SUSY GUT SUSY Seesaw Model
MEG
PRISM
mu2e, COMET,super-MEG
PRISM
MEG
mu2e, COMET,super-MEG
Theoretical predictions are just below the present experimental bound.
54
Minimal SUSY Scenario m2
l=
!
m211m
212m
213
m221m
222m
223
m231m
232m
233
"
slepton mass matrix
∆m2ij �= 0 @ Weak energy scale (100 GeV)
∆m2ij = 0 @ Planck energy scale
New physics at high energy scale would introduce off-diagonal mass matrix elements,
resulting in slepton mixing.
neutrino seesaw mechanism (~1015GeV)
grand unification (GUT) (~1016GeV)
cLFV have potential to study physics at very high energy scale like 1016 GeV.
55
cLFV History
10- 1 4
10- 1 2
10- 1 0
10- 8
10- 6
10- 4
10- 2
1940 1950 1960 1970 1980 1990 2000
Upper limits of Branching Ratio
Y e a r
KL0 → µe
K+ →πµe
µA→eA
µ→ eee
µ→ eγ
Pontecorvo in 1947
First cLFV search
56
Muon Decay In Orbit (DIO) in a Muonic Atom
•Normal muon decay has an endpoint of 52.8 MeV, whereas the end point of muon decay in orbit comes to the signal region.
•good resolution of electron energy (momentum) is needed.
•150 keV energy resolution of electron detection is sufficient for <10-18 sensitivity.
NuFact03@Colombia University2003/6/6
Expected background source - Muon Decay in Orbit -Expected background source - Muon Decay in Orbit -
Muon decay in orbit (!(Eµe-Ee)5)
! Ee > 103.9 MeV! "Ee = 350 keV
! NBG ~ 0.05 @ R=10-18
present limit
MECO goal
PRIME goal
signal
• reduce the detector hit rateInstantaneous rate : 1010muon/pulse
• precise measurement of the electron energy
Background Rate commentMuon decay in orbit 0.05 energy reso 350keV(FWHM)Radiative muon capture 0.01 end point energy for Ti=89.7MeVRadiative pion capture 0.03 long flight length in FFAG, 2 kickerPion decay in flight 0.008 long flight length in FFAG, 2 kickerBeam electron negligible kinematically not allowedMuon decay in flight negligible kinematically not allowedAntiproton negligible absorber at FFAG entranceCosmic-ray < 10^-7 events low duty factorTotal 0.10
10-16 goal
10-18 goal
! (!E)5
57
COMET at J-PARC(for single event sensitivity of 3x10-17)
StoppingTarget
ProductionTarget
58