asymmetry parameter measurements

in nuclear -decayas a probe for

non-Standard Model physics

K.U.Leuven, Univ. Bonn, NPI Rez (Prague), ISOLDE

CERN - INTC 15 November 2004

N. Severijns

STRUCTURE OF THE WEAK INTERACTION IN NUCLEAR BETA DECAY

general Lorentz invariant 4-fermion interaction

h.c. n| |p )( e e5'

i iiii OCCOH

Fermi, 1933 : 4-fermion interaction

Lee & Yang, 1956; Wu et al., 1957 :parity violation

with i = Scalar, Vector, Tensor, Axial vector, Pseudoscalar

and coupling constants Ci defining properties of the interaction types

In the Standard Model :

* CV = 1 (CVC)

* CA = -1.27 ( gA/gV = -1.2697(6) from n-decay )

* CV’ = CV & CA

’ = CA (maximal P-violation)

* CS = CS’ = CT = CT

’ = CP = CP’ 0 (only V- and A-currents)

experimental upper limits:

(neutron and nuclear -decay)

* no time reversal violation (except for the CP-violation described by the phase in the CKM quark-mixing matrix)

/ 0.08

/ 0.06 (95% CL)

T A

S V

C C

C C

from: N. Severijns, M. Beck, O. Naviliat-Cuncic,

Rev. Mod. Phys., accepted

Limits (95 % CL) on possible new bosons for S- and T-interactions, from high-energies:

mass limit for H± (charged Higgs) : > 79.3 GeV (LEP-ALEPH)

mass limit for leptoquarks : > 242 GeV (from pair production; combined CDF-D0)

: > 298 GeV (from single production; ZEUS)

Limits for fT from K± decay [Particle Data group, Phys. Lett. B592 (2004) 1 ] :

|fT / f+| = 0.012(23) from K±e3 decay |fT / f+| < 0.058 (95% C.L.)

|fT / f+| = 0.001(7) from K±3 decay |fT / f+| < 0.015 (95% C.L.)

J

-asymmetry

for a pure Gamow-Teller transition :

(assuming maximal P-violation and T-invariance for V- and A-interactions)

-0.008 < Im (CT+C’T)/CA < 0.014 (90% CL) from 8Li @ PSI, R. Huber et al., PRL 90 (2003) 202301

A/A = 0.01 (for m/Ee 0.5) Re [(CT+CT’) / CA] < 0.040 (95% CL)

recoil corr. (induced form factors) 10-3 (see below) ; radiative corrections 10 -4

AGT independent of nuclear matrix elements

( ) = 1 e

pW J A

E

' 'T T T T

J'JA A

C + C C + C 1 + Im Re

C CGTe

αZm γmA

p E

J'J

2

= 1 for J J 1

J = for J J+1

J+1

= 1 ( Z)

Low Temperature Nuclear Orientation

@ NICOLE

N(θ)( ) 1 cos

N(θ)pol

GTunpol

vW k A P Q

c

cf. IS349 – IS381

,J'J

J'J

1 Re GT T T

AGT

A C Cm m

E E CA

N(θ)( ) 1 cos

N(θ)pol

GTunpol

vW k A P Q

c

cos[ ( ) 1]

[ ( ) 1] cos

vA P Q

W c

vW A P Qc

'T T

J'JA

C + C 1 + Re

CGTγm

AE

1. Absolute measurements

2. Relative measurements

from Geant and

experimental data

cosv

Qc

First case: 114In

1+ 0+ pure GT

E0 = 1.99 MeV

log ft = 4.473(5)

E = 1.70 – 1.85 MeV

= -1.017(20)GTA

N. Severijns, submitted for publication

(m/E = 0.210)

- 0.24 < Re (CT+C’T)/CA < 0.08 (90% CL)

( best precision for A for a fast pure GT transition to date ! )

Isotope transition Eendpoint

(keV)

m/E@

endpoint

AGT log ft recoil correction

*)

P (%)@

10 mK

typeof

meas.

79Kr +, 1/2- 3/2- 604 0.44 -0.333 5.62(12) 54

85mKr -, 1/2- 3/2- 840 0.36 +0.333 5.252(6) 61

79Kr/ 85mKr 0.80 -1 -0.015(5) rel.

67Cu -, 3/2- 5/2- 576 0.43 0.600 6.3 0.004(3) 76 abs.

82gBr -, 5- 4- 444 0.52 -1 5.048(8) -0.004(2) 87 abs.

83Br -, 3/2- 1/2- 931 0.34 -1 5.03(4) -0.005(3) 98 abs.

Proposal

*) due to weak magnetism and induced tensor form factors

if A/A = 0.01 | Re (CT+C’T)/CA |< 0.02 to 0.04 (90% CL)

Other experiments

1. Leuven - AGT

60Co and 133Xe, with LTNO and 15 T external magnetic field instead of hyperfine field

( I.S. Kraev, N. Severijns et al., in preparation )

2. Los Alamos - AGT

82Rb in MOT atom trap; m/E = 0.13

( S.G. Crane et al., Phys. Rev. Lett. 86 (2001) 2967 - D.J. Vieira et al., Hyp.Int. 127 (2000) 387 )

3. LPC-Caen (O. Naviliat et al) - aGT

6He in Paul ion trap

( P. Delahaye al., Hyp.Int. 132 (2001) 479 )

All experiments are aiming at a precision of 0.5% to 1% !

Beam shifts purpose

79Kr 2 AGT

85mKr 8 AGT

67Cu 1 AGT

68Cu 4 implantation quality

82gBr 1 AGT

83Br 10 AGT

82Sr 1 calibrate Geant

118Te (or 118Xe ) 1 calibrate Geant

Total = 28

Beam time request

' 2 2'T T

J'JA

C + C 2 / / 5 1 Re

C 3 3 1JJ

GTn n n

E m E E m Eγm b d E fA

E M Ac M Ac J M Ac

- - -

,' ' ' ' ' 'J'J

J'J

1 Re + TGT T

AGT

A C Cm mb b d d f f

E E CA

Note: effect of recoil terms (induced form factors)

b , gM : weak magnetismc , gA : Gamow-Tellerd , gT : induced tensor