Transcript Study of D-parameter in beta decay

Search for R-parity violating
Supersymmetric effects
in the neutron beta decay
N. Yamanaka
(Osaka University)
In collaboration with
T. Sato (Osaka univ.), T. Kubota (Osaka univ.)
2009年8月12日
at KEK
arXiv:0908.1007 [hep-ph]
Contents
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•
•
•
•
•
Introduction
Neutron beta decay
MSSM and R-parity violation
Neutron Beta decay within RPVMSSM
Analysis
Summary
Introduction
Go beyond the Standard Model
Standard Model:
• Gauge group SU(3)C×SU(2)L×U(1)Y
• 3 generations
• 1 Higgs SU(2)L doublet
gauge boson
lepton
Higgs boson
quark
Reasons to go beyond the SM:
 Hierarchy problems
 Particle-antiparticle asymmetry (too many particles!)
 No candidates of Dark Matter in SM
 Evidence of neutrino oscillations (1998 ～)
…
Approach to New Physics
High energy approach:
Energy above the new physics threshold ⇒ create new particles
Ex: LHC (CERN)
Low energy approach:
Very accurate experiments are now possible:
⇒ Observe the small discrepancy from SM by
precise measurements of low energy phenomena
⇒ Search for New physics beyond SM
Groups:
• J-PARC
• LANSCE
• PSI
• ILL
•…
Phenomena:
• EDMs
• Decay phenomena
• Muon g-2
•…
Neutron beta decay
New physics from beta decay
Neutron beta decay may involve many New Physics
Minimal supersymmetric standard model (MSSM)
R-parity violating MSSM
d
n-e
u
e~L
e-
d
~
dR
n- e
Left-Right symmetric model
Charged Higgs exchange
Leptoquark exchange
u
e-
…
Object
R-parity violating MSSM contributes to the scalar
interaction at the tree level !!
Recently,
• Measurement of R coefficient of the neutron beta decay
(Kozela et al. (PSI), Phys.Rev.Lett.102, 2009)
• Bound on Fierz interference term of the beta decay
(Hardy & Towner, Phys. Rev. C 79, 055502, 2009)
⇒ Both give scalar interaction of the neutron beta decay
Object:
Investigate RPVMSSM contribution to the
neutron beta decay.
Neutron beta decay
Neutron beta decay
Process:
(～100%)
Transition:
Interaction Hamiltonian:
V-A interaction:
Standard Model
n
Scalar interaction: Exotic!
p
n
e~L
W
n- e
p
e-
n- e
e-
Angular correlations
Angular dependence of the beta decay
Decay distribution:
(no polarization)
(neutron polarization)
(e- polarization)
(neutron&e- polarization)
neutrino momentum & e- polarization:
⇒ new terms!!
Jackson, Treiman, Wyld, Nucl. Phys. 4, 206 (1957)
MSSM and R-parity violation
Supersymmetry
Symmetry between boson & fermion:
⇒ Each particle has a “super-partner”
⇔
fermion
boson
Why SUSY?
•
•
•
•
SUSY cancels power divergences (Fine tuning)
SUSY can break the EW symmetry
Accurate GUT at 1016GeV
Dark matter, etc.
…
Minimal Supersymmetric Standard Model (MSSM):
⇒ Gauge invariant, renormalizable,
R-parity conserving
⇒ Phenomenological
extension of the SM!!
⇔
particles
s-particles
R-parity violation
R parity:
⇒Conservation of baryon and lepton number in MSSM.
RPVMSSM:
Add R-parity violating interactions to the MSSM
d
□R parity violating lagrangian:
u
e~L
L or B violating
Neutron beta decay
within RPVMSSM
Steps of calculation
Plan:
Beta decay within R parity violating MSSM
Neutron Beta decay effective interaction
Angular correlation (coefficients)
RPV lagrangian & limits
RPV lagrangian:
d
u
e~L
Yukawa interaction!!
[…] : sfermion mass in unit of 100 GeV
Coupl.
Current upper bounds
Sources
λ121
< 0.049 [meR]
CC universality
λ131
< 0.062 [meR]
t decay ratio
λ’211
< 0.059 [mdR]
p decay ratio
λ’311
< 0.11 [mdR]
t/p decay ratio
λ’111
< 1.3 x 10-4 [mq]2~[mg]1/2~
double beta decay
λ’112
< 0.021 [msR]
CC universality
λ’113
< 0.021 [mbR]
CC universality
Barger, Giudice, Han, Phys. Rev. D409, 2987 (1989)
Barbier et al., Phys. Rept. 420, 1 (2005)
Faessler, Kovalenko, Simkovic, Phys. Rev. D58, 115004 (1998)
Neutron beta decay with
R-parity violation
d
u
SM contribution:
W
n- e
ed
u
Selectron exchange diagram:
e~L
n- e
ed
u
Down squark exchange diagram:
~
dR
-n
e
Absorbed in Vud ⇒ Neglect
e-
Effective interaction
Effective interaction constructed from quark amplitude:
(pseudoscalar interaction neglected due to non-relativistic approx)
Vector, axial and scalar constants:
(CVC assertion)
(Experiment)
(Our work)
V-A only (SM)
RPV contribution
a
(1-2) / (1+32)
0
b
0
aR
Approx. used:
A
2(1-) / (1+32)
0
• Static approx. of nucleon
• Scalar & V-A interference
only
• O(me/MN) neglected
B
2(1+) / (1+32)
(me/Ee) aR
D
0
0
G
-1
0
H
(me / Ee) (2-1) / (1+32)
- aR
K
(2-1) / (1+32)
aR
L
0
aI
N
2(me / Ee) (1-) / (1+32)
- aR
Q
2(1-) / (1+32)
aR
R
0
-aI
S
0
aR
T
0
aI
U
0
aI
V
-2(1+) / (1+32)
0
W
0
-aR
Result
Experimental value
V-A only (SM)
RPV contribution
a
-0.103 ± 0.004
-0.105
0
b
(Hardy & Towner)
0
5.12 x 10-3
A
-0.1173 ± 0.0013
-0.117
0
B
0.981 ± 0.004
0.988
6.50 x 10-3 x (me/Ee)
D
(-2.8 ± 6.4 ± 3.0 ) x 10-4
0
0
G
-1
0
H
0.105 x (me/Ee)
-5.12 x 10-3
K
0.105
5.12 x 10-3
L
0
5.12 x 10-3
0.117 x (me/Ee)
-6.50 x 10-3
0.117
6.50 x 10-3
0
6.50 x 10-3
S
0
6.50 x 10-3
T
0
-6.50 x 10-3
U
0
-6.50 x 10-3
V
-0.988
0
W
0
-6.50 x 10-3
N
0.056 ± 0.011 ± 0.005
Q
R
0.008 ± 0.015 ± 0.005
Analysis
Survey of superallowed Fermi
transition
Test of CVC with 20 superallowed 0+→0+ beta decay.
CVC assertion ⇒ Vector interaction not renormalized
Ft identical in nuclear medium for 0+→0+ transition
Test of CVC:
Corrected Ft value
(isospin symmetry breaking correction
and radiative corrections)
In 0+→0+ transition, effect of (real part of) scalar
interaction shows up in Fierz interference term
Fierz interference term ⇒ limit to Re(Cs) !!
J.C. Hardy, I.S. Towner, Phys. Rev. C79, 055502 (2009)
R coefficient
R correlation:
Sensitive to the imaginary part of Cs
Experimental status:
Rexp = 0.008 ± 0.011 ± 0.005
Kozela et al.(PSI), PRL102 (2009)
SM:
RSM ≦ 10-14
Herczeg, Phys. Rev. D56 (1997)
Final state interaction:
Rfsi = 0.00086 × me/pe
Jackson, Treiman, Wyld, Nucl. Phys. 4, 206 (1957)
10-14
SM
10-4
FSI
10-2
RPV
Exp
New bounds
R coefficient from Kozela et al.
Hardy & Towner’s work
Source value
R = 0.008 ±0.011 ± 0.005
bF/ 2 = 0.0011 ± 0.0013
Cs /Cv
-0.0184±0.0253 ± 0.0115
0.0011±0.0013
S l1i1l’*i11 / [meL]2
-0.012±0.017±0.008 (imaginary)
(7.2±8.5) x 10-4 (real)
Current limit:
(plot with all mSUSY= 100 GeV)
Summary
We have investigated the R-parity violating
contribution to the neutron beta decay.
The following new constraints were established:
Future prospects
D coefficient:
V-A only (SM)
Fsi
RPVMSSM
0
O(10-5)
0 (tree level, O(me/mn) contribution neglected !)
L, S, T, U, W coefficients:
Zero in V-A only (SM), but RPV contributions exist
S,T,U,W are direct probe of the real part of scalar interaction!!
Loop contribution:
d
Non-scalar interactions at the one-loop level.
⇒ Possibility of large contribution to some angular correlations?
_
ne
u
W
e-