Unexpected features at twopion threshold

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Unexpected features at two-pion threshold
M. Bashkanov

• Experimental setup
• Results
• peak at ?? threshold
• small peak at ?? threshold
• Summary

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Theodor Svedberg Laboratory
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CELSIUS storage ring
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Pellet Target
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WASA 4? Detector
?,p
3He
?, p
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ABC effect(Abashian, Both, Crowe )
Missing mass GeV/c2 .3 .4
.5 ?

• Inclusive measurements
• pd ? 3He X
• 
  
• Abashian et al. Berkeley
• Banaigs et al. Saclay
• ?
• low-mass enhancement !

Q 0.3 deg
pd 3.14 GeV/c ? Tp 893 MeV
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pd?3HeX
?/8
?/4
3?/8
?/2
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(No Transcript)
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3Hep invariant masses
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Angular distributions
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pd?3He??, I(??)1 ?-meson contribution
M?0.77GeV ??0.15GeV ??0.3?b
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?(pd?3He??)

• ?(pd? 3He?0?0) 2.8?b
• ?(pd? 3He??-, (I0) ) 5.1?b
• ?(pd? 3He??-, (I1) ) 0.3?b

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Enhancement at
threshold
Jun 2005
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Conclusion

• ?? threshold reveals unexpected behavior.
• Similarities in ,
• dynamic CSB by pp loops in region between p0p0
  and pp- thresholds ?
• threshold state ?
• ???

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WASA at COSY
Uppsala
Juelich
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Tp 775 MeV Tp 1100 MeV