Observation of charged k at BESII
Observation of charged at BESII
Observation of charged k at BESII> KwasfirstfoundinKscatteringdata> However,itsphase shift is much less than180o and it cannotbefilled into any nonets of ordinary rresons.There have been hotdebatesontheexistenceofInrecentyears:inD+FNALE791foundevidenceofneutralK- + +.M=797±19±43MeV/c2,=410±43±87MeV/c2K- CLEODOOdatafindno evidenceof+FOCUSdataonD+K-++require K*ointerfere witheitheraconstantamplitudeora broadO+resonance inKBESllobservedneutralkinJ/y→K*0K元→K元K元in20062pole:neutral= (841+ 30+81)- i(309 ± 45+48) MeV/c217
Observation of charged at BESII ➢ was first found in K scattering data ➢ However, its phase shift is much less than 180o and it cannot be filled into any nonets of ordinary mesons. There have been hot debates on the existence of . In recent years: ◆ FNAL E791 found evidence of neutral in D+ K- + +. ◆ CLEO D0 K- + 0 data find no evidence of . ◆ FOCUS data on D+ K- + + require K*0 interfere with either a constant amplitude or a broad 0+ resonance in K . ◆ BESII observed neutral in J/ → K*0K → KK in 2006. neutral pole: 𝑞𝑞LJ 𝑚 + 𝑖 𝛤 2 = (841 ± 30−73 +81) − 𝑖(309 ± 45−72 +48) MeV/c2 𝑀 = 797 ± 19 ± 43 MeV/c2 , 𝛤 = 410 ± 43 ± 87 MeV/c2 12