3-12-2004 NIKHEF Fokke de Boer 1

anomalous internal pair conversion

as a sign for elusive

light neutral particles

e+

e–

3-12-2004 NIKHEF Fokke de Boer 2

anomalous internal pair conversion

as a sign for elusive

light neutral particles

e+

e–

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co-authorsJohan van Klinken 1

Helmut Bokemeyer 2

Klaus Bethge 3

Oliver Fröhlich 3

Alkis Müller 3

Kurt Stiebing 3

Margo Csatlós 4

Zoltan Gácsi 4

Janos Gulyás 4

Mathias Hunyadi 4

Attila Krasznahorkay 4

Zoltan Máté 4

René van Dantzig 5

Tjeerd Ketel 5

1 Groningen2 Darmstadt3 Frankfurt

4 Debrecen5 Amsterdam

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light neutral particles

• upper limits

• in emulsions

• in nuclear transitions

• spectroscopy

• and dark matter

branching ratios

511 keV radiation

pair production

anomalous IPC

fantasy

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candidate bosons

o light Higgs (0+) to explain muonic X-rays anomalies

Watson and Sundaresan (1971)o axion, a light pseudoscalar boson (0-) invented to

prevent large CP-violations,

Peccei and Quinn (1978)o U-boson a supersymmetric gauge boson (1+, 1-) ,

Fayet (1981)

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particle data book

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allowed window (not for T=1 axions)

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emulsion events

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spin-parity conservation.

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width

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EEEy

yEmX

/)(

)2

(sin)1( 2222

correlation angle ω (degrees)

number ofIPC pairs(a.u.)

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detector array

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studied reactions

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alpha nuclei

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agreement with E1-IPC in 12C

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agreement with IPC in 12C and a deviation in 8Be

Phys.Lett. B388 (1996) 235

7Li(p,)8Be 1+, T=1, 17.6 MeV11B(p,)12C 1-, T=1, 17.2 MeV

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isoscalar decay from 18.15 MeV in 8Be

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results from IKF, KVI and SUNY branching ratios and widths

an isoscalar boson scenario with mass of 9 MeV/c2, with spin 0- or 1+,and coupling strength αX

proportional to the isoscalar width in the magnetic transition.

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KVI annual report 2002

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16O (0-,T=0) 10.96 MeV decay

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To be published in Phys. Rev. Lett.

16O (0-,T=0) 10.95 MeV decay (M0 transition !!)

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boson search program

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8Be (1+,T=1) 17.64 MeV decay

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8Be (1+,T=0) 18.15 MeV decay

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16O (0-,T=0) 10.96 MeV decay

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12C (1+,T=0) 12.71 MeV decay

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12C (1+,T=1) 17.23 MeV decay

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16O (0+,T=0) 6.05 MeV decay

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16O 6.05, 8.87, and 10.96 MeV decay

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SPI data are consistent with positrons that originate from centre of the Galaxy and either: • low-mass X-ray binaries, • novae, • type Ia supernovae, • or possibly light dark matter.

INTEGRAL satellite

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summary• anomalous internal pair conversion is observed

in isoscalar nuclear transitions

• magnetic monopole transition in 16O is found

• several candidates for isoscalar neutral bosons in the 2-15 MeV mass region are reported

• one of the vector boson candidates may be the U-boson and be intermediate in the annihilation of light dark matter