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Search for the decay B c B s p

Search for the decay B c B s p. Masato Aoki July 19, 2006. Introduction. B c : bottom and charm quark bound state Decay: b c : ~25% : ( J/ y l n , J/ yp ,J/ y D s ) cs : ~65% : (B s l n ,B s p ,B s * r ) annihilation : ~10% B(B c J/ y e n ) ~ 1.9% (hep-ph/0308214(2003))

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Search for the decay B c B s p

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  1. Search for the decay BcBsp Masato Aoki July 19, 2006

  2. Introduction • Bc : bottom and charm quark bound state • Decay: • bc : ~25% : (J/yln,J/yp,J/yDs) • cs : ~65% : (Bsln,Bsp,Bs*r) • annihilation : ~10% • B(BcJ/yen) ~ 1.9% (hep-ph/0308214(2003)) • B(BcJ/yp) ~ 0.13% • B(BcBsp) ~ 16.4% • BsJ/yj at first (less CPU time) • Next : BsDsp Observed

  3. Mass distribution : MC smass~5 MeV/c2 (smass(BcJ/yp)~15 MeV/c2) Mass constraint on Bs and J/y

  4. BsJ/yj : 360pb-1 Bsy(2S)j analysis • Cuts from note7525 (Bsy(2S)j analysis) • No L00, special good run • Consistent result : ~290 events 292.2±15.9 298.2±19.1 hbJ/yJ/y analysis 295.0±18.7

  5. BsJ/yj : 1.1fb-1 hbJ/yJ/y analysis • DQM good run • Use L00 • ~950 Bs events 960.2±33.5 952.9±32.4

  6. MC sample • pT(B)>0, |y(B)|<1.3, run range:360pb-1 • BsJ/yj (pT from pT(Hb)) • 107 generated, 421313 triggered • BcBsp, BsJ/yj (pT from theory) • 107 generated, 336755 triggered • BcBsp, BsJ/yj (pT from pT(Hb)) • 107 generated, 370728 triggered

  7. pT(Bs): data v.s. mc • MC : • pT(Bs)>0 • |y(Bs)|<1.3 • pT spectrum from inclusive Hb • Cuts from note7525 • can see some discrepancy • trigger effect? Bsy(2S)j analysis pT(b)>0,|h(b)|<1.3,NDE

  8. pT(J/y): data v.s. mc Bsy(2S)j analysis *after pT(Bs)>6.5GeV cut

  9. Some parameters • σ(Bc)×BR(Bc→J/yeν) / σ(Bu)×BR(Bu→J/yK) = 0.314 ± 0.043 ± 0.039 ± 0.096 (pT > 0 GeV, |y| < 1) (total uncertainty=0.112)= 0.282 ± 0.038 ± 0.035 ± 0.065 (pT > 4 GeV, |y| < 1) (total uncertainty=0.083) • BR(Bc→J/yeν) = 1.9 ± 1 % • BR(Bc→Bsπ) = 16.4 ± 1.6 % • BR(Bu→J/yK) = (1.00 ± 0.04) × 10-3 • Production ratioBu:Bd:Bs:b-baryon = (39.7±1) : (39.7±1) : (10.7±1.1) : (9.9±1.7) %

  10. Bc production cross section (|y|<1) • σ(Bc) / σ(Bu) = 0.314 × 0.001 / 0.019 = 0.0165 (±0.0105) • σ(Bc) / σ(Bs) = σ(Bc)/σ(Bu) × σ(Bu)/σ(Bs) = 0.0165 × 39.7 / 10.7= 0.0613 (±0.0396) • σ(Bc)×BR(Bc→Bsπ) / σ(Bs) = 0.0613 × 0.164= 0.0101 (±0.0066)

  11. Expectation in BsJ/yj channel • N(Bc)= σ(Bc)×B(Bc→Bsπ)/σ(Bs) × N(Bs) × ε(Bc)= (0.01) × (950 × 107 / (4×104)) × (N(Bcrec) / 107)= 2450 × (N(Bcrec) / 107)= 2450 × (∼9000 / 107)= ∼ 2 events If use cuts : pT(j)>0.9 GeV, pT(p)>1.2 GeV Lxy2Pv(Bs)>280 mm *before cuts : N(Bcrec)~40000

  12. Summary • ~2 events are expected in BsJ/yj1.1fb-1 data (at least 65% uncertainty) • May increase the number by cut optimization study • To do • Check Bs MC • Cut optimization. Which cuts? • Reflection from BcBsX? • Mass constraint on Bs? J/y? j? • Bs massPDG 2004 : 5369.6 ± 2.4 MeVCDF 210 pb-1 : 5366.01 ± 0.73 ± 0.33 MeV  Use when constrain Bs mass http://hep-www.px.tsukuba.ac.jp/~masato/Bc/BsPi/

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