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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

qq

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+