Introduction The CLEO detector and Y(5S) data sample Analysis techniques: Exclusive approach Inclusive approach Summary

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1 Introduction The CLEO detector and Y(5S) data ample Analyi technique: Excluive approach Incluive approach Summary Victor Pavlunin Purdue Univerity CLEO collaboration Preented at Firt Meeting of the APS Topical Group on Hadronic Phyic, FNAL, Oct 24-26, 2004 October,

2 Introduction (1) The Y(5S) reonance wa dicovered by CLEO and CUS collaboration operating at CESR in The Y(5S) reonance i maive enough to decay into the following channel:,,, π, π, π, ππ,,, No concluive evidence for production at the Y(5S) wa found in 116/pb of data collected in Knowledge of production at the Y(5S) i eential for aeing the potential of phyic at a high luminoity electronpoitron collider. The three channel with meon are in the focu of two current CLEO tudie. PDG 2004 : M M M CDF 2004 : M Y (5S ) = ( ± 0.008) GeV Γ = (110 ± 13) MeV = (5.370 ± 0.002) GeV M = (47.0 ± 2.6) MeV = ( ± ( tat + y)) GeV October,

3 Introduction (2) Two paper exit that decribe the hadronic cro ection above the Y(4S) reonance: CLEO: PRL 54, 381 (1985) CUS: PRL 54, 377 (1985) The cro ection above the Y(4S) reonance i decribed reaonably well by Unitarized Quark Model (S.Ono et.al., Phy.Rev.D 34, 186 (1986)). The model predict: Y(5S) or, The total cro ection of Y(5S) ~ 1/3. σ(e + e - Y(5S)) ~ 0.35 nb (compare thi to the b-quark cro ection in pp colliion) October,

4 The Data Sample and CLEOIII detector The Y(5S) Data ample: 0.42/fb collected with the CLEO III detector in 2003: if σ(e + e - ()() ) ~ 0.1 nb, expect ~ 90K of meon in 0.42/fb The background i tudied uing the ON Y(4S) CLEO III data The continuum (e + e - qq) background i tudied uing the OFF Y(4S) CLEO III data, taken 30 MeV below the Y(4S) October,

5 Experimental technique Incluive approach Soft photon pectrum (from () ) Lepton pectra (dependent on () mae) Yield of particle with one or two -quark Excluive approach J D () /ψ h and D π / l () ν Thi i work in progre. The ICHEP reult will be hown. ρ October,

6 EXCLUSIVE APPROACH October,

7 The recontruction technique ued at the Y(4S) are employed to recontruct the meon at the Y(5S): M Overview of excluive method bc = E 2 beam P 2 candidate E = E beam E candidate The continuum (e + e - qqbar) background uppreion variable Three decay channel of Y(5S) to meon are poible producing three peak in Mbc : Decay channel 1: Decay channel 2: Decay channel 3: (Note the ign of E) Y (5S) : E = Decay channel: 1, 3, 2 Signal MC October, E beam Y (5S) : E = E beam Y 5S) : E > E, E ( PDG 2004: M M Aumption: CDF 2004: M beam = (5.370 ± 0.002) GeV M = ( ± ( tat+ y)) GeV < E = (47.0 ± 2.6) MeV beam ( γ) = 100%

8 Analyi background The Y(5S) reonance cay decay into a variety of tate with ordinary meon,, π, π, π, ππ Thee decay are a ource of background in the earch a hown in the plot The continuum (e + e - qqbar) background i large: σ ( ) ~ σ ( e e qq) () () σ ( ) ~ σ ( e e qq) decay mode are poorly known. The center of the ignal band for ordinary meon π ππ The center of the ignal band for meon M () M ( ) October,

9 Important election criteria R2 and co(θ thrut ) : R2 H 2 /H 0 ratio of Fox- Wolfram moment of the event θ thrut i the angle between the thrut axi of the candidate and the thrut axi of the ret of the event Ma window cut for wide particle uch a ρ, K. co(θ helicity ) for the P V(pp)P mode in the D recontruction θ helic R2 H 2 /H 0 bar event co(θ thrut ) The continuum K - The continuum meon ϕ K + D π + October,

10 Gold plated mode Search for very clean mode having extremely high S/ ratio (unfortunately with mall branching fraction). The bet candidate mode i J/ψ ϕ, analogou to 0 J/ψ K. The earch i made for J/ψ η and J/ψ η a well. J/ψ i recontructed in µµ and ee channel, the following clean channel are ued for other particle: ϕ KK, η γγ, η ηπ + π -. Expect to find only a few ignal count, auming branching fraction imilar to thoe for ordinary. J /ψ + µ µ φ K + K October,

11 Ditribution in the Data Prelim The boxe how the ignal region auming the CDF ma. Prelim 4 count in the ignal box for Y(5S) : 3 count in J/ψϕ (in black), 1 count in J/ψη (in blue). Thi i a compelling evidence for the preence of the in the Y(5S) data a the background level i etimated to be le than 0.1 event (prelim). The beam energy cale i being tudied for the ma meaurement. October,

12 October, One of the ignal event + + K K J J and S Y φ µ µ ψ ψ φ γ, /, /, ) (5 µ - µ + K - K +

13 Recontruction of D() π - /ρ - Mode for : R are from the correponding R for 0 Mode for D(): The choice of D() π/ρ and the four clean D mode lited above i motivated by the difficulty of background modeling. Monte Carlo imulation uing the branching fraction above predict a total of 9 event can be recontructed in thee channel, ubject to tatitical fluctuation. October,

14 Ditribution in the Υ(5S) data The boxe how the ignal region auming the CDF ma. Prelim Prelim D π : D D D π : ρ ρ 2 event 4 event 1event 1event We find 8 event in the ame upper ignal box and etimate that the level of background i approx. 1.0 event (or le, prelim). Therefore, we have etablihed an evidence for the meon in the D () π - /ρ - mode a well The beam energy cale i being tudied for the ma meaurement. October, : :

15 Summary for Excluive Recontructrion We have hown evidence for the meon in the CLEO Y(5S) data uing excluive recontruction in two different type of decay mode. The Y(5S) reonance favor decay to over thoe to or, which i conitent with model prediction. We intend to add the emileptonic mode D () l ν in order to improve meaurement of the total production rate at the Y(5S) energy. Expect the reult for σ ( ) / σ ( ) and σ ( + ) / σ ( ) the ma of and, poibly, the total production rate at Y(5S) energy from thi approach to be available in early pring October,

16 INCLUSIVE APPROACH More information i available in arxiv:hep-ex/ October,

17 Overview of the incluive method The D meon i expected to be produced in decay more copiouly than in decay (PDG): ( D X) = (94 ± 30)% ( D X) = (10.5 ± 2.6)% Incluive analyi tep: Meaure D yield in bin of x = P D /E beam in the continuum, Y(4S) and Y(5S) data. Meaure (Y(4S) DX) and (Y(5S) DX) by ubtracting properly caled and normalized continuum yield from the Y(4S) and Y(5S) yield. Extract (Y(5S) () () ) from the meaured (Y(4S) DX) and (Y(5S) DX). October,

18 D ϕ π + incluive recontruction The decay equence D ϕ π +, ϕ K + K - i ued. The recontruction efficiency i ~30% and it i independent of the beam energy for the three data et. The plot how raw D yield in the Y(5S) and Y(4S) data. The raw D yield are corrected for the contribution from the continuum. The continuum data are caled in the following way: S = L L cont E E cont 2 October,

19 D pectra at Y(4S) and Y(5S) The plot how the continuum ubtracted and efficiency corrected D yield at the Y(4S) and Y(5S). No D branching fraction correction wa applied to be above plot. Uing (D ϕπ) = (3.6±0.9)%, CLEO find: ( Y (4S) D Thi work : PDG : X ) = (22.3 ± 0.7 ± 5.7)% ( D X ) = (11.1 ± 0.4 ± 2.9)% ( D X ) = (10.5 ± 2.6 ± 2.5)% ( Y (5S) D X ) = (55.0 ± 5.2 ± 17.8)% ( Y (5S) D X ) / ( Y (4S) D X ) = 2.5 ± 0.3 ± 0.6 October,

20 Reult for the incluive method The plot how an exce in the D production at the Y(5S) over that at the Y(4S). The exce i interpreted a an evidence for at the Y(5S). From (Y(4S) DX)) and (Y(5S) DX)), CLEO make a model dependent etimate: ( Y (5S) () () ) = (21± 3( tat) ± 9( y))% The larget contributor to the ytematic error are the uncertainty aociated with the continuum ubtraction the error from the uncertainty in (D ϕπ). Expect improvement in the ytematic error October,

21 Summary and outlook Evidence for the meon at the Y(5S) reonance i found in both excluive and incluive approache It i found that () () ( Y (5S) ) = (21± 3( tat) ± 9( y))% The Y(5S) decay predominantly to rather than to or. All reult are preliminary Further tudie are ongoing. Expect finalized reult in the near future (pring, 05). October,