Observation of an anomalous enhancement near the threshold of pp mass spectrum at BES lI BEsJ∧+pp acceptance weighted BW M=1859+3+5MeV/c2 10-25 T<30 Mev/c2(90% cl 100 却地 x/dof=5656 0.1 0.2 0.3 Phys. Rev. Lett. 91,022001(2003) Mpp)-2mp(GeV) 3-body phase space acceptance
Observation of an anomalous enhancement near the threshold of mass spectrum at BES II M=1859 MeV/c 2 G < 30 MeV/c 2 (90% CL) J/pp M(pp)-2mp (GeV) 0 0.1 0.2 0.3 3-body phase space acceptance c2 /dof=56/56 acceptance weighted BW +3 +5 10 25 pp BES II Phys. Rev. Lett. 91, 022001 (2003)
Features of the enhancement near the threshold of pp mass spectrum at BES II BEs‖J∧+γpp Peak position: 0 Mev above threshold 150 “ Width 100 60M eV 8p Strong(“ Height") (s+B)B~2 The above features may 00.10.20.3 help us easily to judge whether it is observed in Mpp)-2m,(GeV) other processes
Features of the enhancement near the threshold of mass spectrum at BES II J/pp M(pp)-2mp (GeV) 0 0.1 0.2 0.3 pp BES II § Peak position: ~ 0 MeV above threshold § “Width”: ~ 60M eV § Strong (“Height”): (S+B)/B ~ 2 The above features may help us easily to judge whether it is observed in other processes
This narrow threshold enhancement is NOT observed in qq<(alY at CLEO This result cannot be Br(Y(1S)→yx)/Br(/v→>yX) explained by pure FSl effect, since fsl is a universal effect <0.7%@90%CL FSI interpretation of the narrow and strong ppar threshold enhancement is 10 disfavored This indicates that X(1860) has a production property 192.12.32 27293.1 similar to n meson M(pp)(GeVIc- c.f. FIG.7:Inyariant mass of pp from T(1s) Br(Y(1S)→ym)Br(/y→ym) No enhancement near threshold <049@90%CL
§ This result cannot be explained by pure FSI effect, since FSI is a universal effect. FSI interpretation of the narrow and strong ppbar threshold enhancement is disfavored. § This indicates that X(1860) has a production property similar to ’ meson. c.f.: This narrow threshold enhancement is NOT observed in pp ) S1( at CLEO No enhancement near threshold CL Br S Br J 0.7% @ 90% ( (1 ) X)/ ( / X) CL Br S Br J 0.4% @ 90% ( (1 ) ')/ ( / ')
This narrow threshold enhancement is NOT observed in qqo< L at BESII This again disfavors FSI Br(J/>)/Br(Jly>y X) and indicates that X(1860) <0.5@95%Cl has a production 25829.58 eom2.534E- property similar to n' or 40-.. bcaie C.L.=1.9% Minos -0000+0.00 meson. 0.000 0 0000 +.000 0. 0.00 000 +0.000 0.000 +0.000 c.f.: 9.5157E-02-0 0000 0.000 + Br(Jy→n)/Br(Jy→yn) 60 ≈0.04 40 ≌ .This also indicates X(1860) may have strong 0 005 mpp-2mp(Gev/c).15 0.10 0.20 coupling to gluons as n' meson. No narrow strong enhancement near threshold
§ This again disfavors FSI and indicates that X(1860) has a production property similar to ’ meson. c.f.: § This also indicates X(1860) may have strong coupling to gluons as ’ meson. This narrow threshold enhancement is NOT observed in pp / Jat BESII No narrow strong enhancement near threshold CL Br J Br J 0.5 @ 95% ( / X)/ ( / X) 0.04 ( / ')/ ( / ') Br J Br J
Pure Fsi disfavored =0 S-wave FSI CANNOT fit the bes data 150 FSI curve from A. sirbirtsev et al.( Phys. Rev. D71: 054010 2005)in the fit(O) x2d.0.,f=192/58 100 9>0o8°9 FS|· PS* eff+bck 0.00 0.10 0.20 0.30 n P
Pure FSI disfavored I=0 S-wave FSI CANNOT fit the BES data. M pp mp 2 / . . 192 / 58 2 c d o f FSI * PS * eff + bck FSI curve from A.Sirbirtsev et al. ( Phys.Rev.D71:054010, 2005 ) in the fit (I=0)