prospect for Bc->BsPi II (Bs->DsPi)

prospect for Bc->BsPi II(Bs->DsPi) tomoyo fukami @BMLCPV(2008/7/29)

目次 • method • signal & background • cut • plot • backgound estimation • conclusion

method • mode • Bc->BsPi->DsPi->PhiPi • Bc->BsPi->DsPi->K*K • Bc->BsPi->DsPi->3Pi • using momentum and vtx , reconstruct track(K,Pi) in order of Ds mass -> Bs mass ->Bc mass • data（signal : MCandbkg : Data (two track trigger)）

signal & background • signal : Bc->BsPi • bkg : • Bc->Bslνπ • Bc->Bs*π->Bsγ • Bc->BsK • P.V. Bs+π • fake Bs Bc BranchingFluction →use sideband data for bkg

cut parameters • pre selection Philipp Mack ph.D thesis IEKP-KA/2007-10(2007)

cut parameters • BOX cut

plots K*K Bc->BsPi only Vtx construct required preselection cut base PhiPi 3Pi

K*K 3σ PhiPi 3Pi consideration • we estimated the number of signal and background (asBc,Bs*Pi,other) in signal window. M(Bc)-M(Bs) gauss fit mean±3σ: signal window

asBc background 1 K*K asBc : PV Bs but able to reconstruct Bc combinatoraliy with a pion in fragmentation. after pre selection cut PhiPi 3Pi

asBc background　２ K*K asBc : PV Bs but able to reconstruct Bc combinatoraliy with some pion. after BOX cut PhiPi 3Pi

calculation of n(expected)after pre selection cut • Philipp Mack ph.D thesis IEKP-KA/2007-10(2007) how many events (Bc->BsPi)are obserbed ? and how many events (asBc bkg)are observed? εis obtained from MC the number of event in signal window

conclusion • The “asBc” background is enough small after applying pre selection cut • Bc->BsPi :”asBc” type background event is nearly negligible in DsPi mode.

plan summary • we checked the efficiency of the BOX cut of Bc->BsPi->DsPi->PhiPi(,K*K,3Pi). • we estimated the effect of “asBc” type background after applied by pre selection -> negligible • we estimated the effect of “BsX” type background after applied by preselection -> negligible • combinatorial background looks dominant • estimation of other combinatorial background. • To reject combinatorial background using NN(well known).

buck up

consideration • signal Bcのmass window でのasBc(bgd)の割合について M(Bc)-M(Bs)の gauss fit ＊出来ればプロットと、パラメータをROOTで出力

back ground について • signal に関与しない領域（sideband）のDataをもちいてback ground とする。 signal sideband

introduction • QCD, EW　の良いテストベンチ(quarkonium以外で唯一の heavy quark ふたつから成る粒子) • QCD計算モデルの検証（特にクオークの束縛状態モデルや、重いクオーク系での有効理論の検証） • 質量 • 寿命　etc… • 各終状態への相対崩壊分岐比 • 理論の検証や上記物理量の抽出に重要。 • 理論予測ではBc->BsX　に次いで大きな分岐比を持つが、未発見 • Bs振動やCP位相安定性の測定に用いる、Bsフレーバー同定のためのBs寿命測定への影響を正しく考慮できる

asBc background K*K asBc : PV Bs but able to reconstruct Bc combinatoraliy with a pion in fragmentation. after pre selection cut PhiPi 3Pi

prospect for Bc->BsPi II (Bs->DsPi)