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AntimatterAntimatter
Jan Meier
Seminar: Experimental Methods in Atomic Physics
May, 8th 2007
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Overview Antimatter and CPT theorie
what is antimatter?
what physics does it follow to?
First observations of antimatter
Natural sources of antimatter
Artificial sources of antimatter and experiments withantihydrogen
PS210, E862 (first detections of)
ATHENA, ATRAP (spatial and velocity distribution andtemperature measurements)
ALPHA (trapping of)
AEGIS (gravity measurement)
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Antimatter and CPT theorie
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( ) 0, 2rrrrr
hh =
+
trcmci
ti e
Dirac equation of a free electron
Prediction of antimatter
solution delivers two energy eigenvalues:
4222 cmpcE e+=r
Does negative enery eigenvalue have physical meaning?
1928 - Paul Dirac(Nobel prize 1933)
(P.A.M. Dirac, Proc. R. Soc. A 117 (1928) 610)
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=
z
y
x
r
=
0001
0010
0100
1000
x
=
000
000000
000
i
ii
i
y
=
0010
0001
1000
0100
z
=
1000
01000010
0001
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Dirac interpretation
e+ is a hole
e-
Dirac sea e-
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1949 Feynman-Stckelberg interpretation
Positron is a particle (not a hole)
Positron is a (positively charged) electron,travelling backwards in time
positron
electron
some other electron
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CPT-TheoryTransformations C, P and T:
xxrr
P (parity inversion)C (charge conjugation)
T (time inversion) tt
CPT transformation:
),,(),,( txqftxqf rr
BB ;
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A CPT transformation transforms a particle intoits corresponding anti-particle
particle Anti-particle
e- e+
CPT
txq ,,
r
txq ,,
r
Standard Model:
For every particle type there is a corresponding
antiparticle type
(some electrically neutral bosons, like Z0, and c
= are their own
antiparticles)
cc
CPT Symmetry
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CPT invariance
Physics (i.g. all physical laws, equations, processes) is invariant
under CPT transformations
=
t
iH h
+
CPT transformation
)()(
=
tiCPTHCPT h
+ +
p H
e- e+
under certain conditions, relativistic quantum field theories say:
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Prospect of spectroscopy
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Violation of CPT invariance
String theory
Kostelecky (standard model extension)
Historical: P (theory:Lee,Yang; Exp.:Wu), CP violations (J.H.
Christenson)
(R. Bluhm et al., Phys. Rev. Lett. 82 (1999) 2254)
(C.S. Wu et al., Phys. Rev. 105 (1957) 1413)
(J.H. Christenson et al., Phys. Rev. Lett. 13 (1964) 138)
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Matter-antimatter asymmetry
Big Bangenergy
???
tt=0 now
matter
antimatter
matter+
possible explanations:
CPT violation, breaking of Baryon number conservation
CP violation, breaking of Baryon number conservation, out of
equilibrium situation
energy
(H.R. Quinn, SLAC-PUB-8784 (2001))
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First observations of antimatter
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First detection of antimatter
1932 - Carl Anderson
From particle track:
eqPositron 2+