DDRecent D0 results on

QuarkoniumHAN, Liang Univ. of Science & Technology of China

Univ. of Manchester presenting D0 Collaboration

(commented by Rick Van Kooten D0 B-convener)

- Tevatron & D0 Run2 - X(3872) - Bc meson - Upsilon(1S)

DD Tevatron & DØ RunII

• com: 1.96 TeV PPbar• lumi: 2E32 cm-2s-1

• Xing: 396 ns

Main Injector(new)

Tevatron

DØCDF

Chicago

p source

Booster

DD

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Pseudo rapidity: ln(tg(Spatial separation: △R2=△2+△2

Tracking & Vertex: - Silicon Microvertex Tracker (SMT) + Central Fiber Tracker (CFT) + 2T Solenoid - good tracking, vertex, impact parameter measuring performance

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DDMuon system: - 3 layer, 1 layer (A) in 1.8T Toroid - Good coverage: central ||<1 forward 1<||<2 - Muon-Tracking match muon candidate - fast and efficient Di-Muon Trigger

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The observation ofX(3872) J/(+-) +-

DDFirst observed confirmed

DDEvents Selection:

- Apr 02 – Jan 04, ~230pb-1

- di-muon triggered

- 2 well identified muon tracks, opposite charged - 2.80 ＜ M(+-) ＜ 3.35 GeV/c2

- pT(+- ＞ 5 GeV/c2

- 2 opposite charged tracks, with spatial separation as △R(J/+-, each ) ＜ 0.4 - pT() ＞ 0.7 GeV/c2

- M(+-) ＞ 0.52 GeV/c2

- A good () Vertex, for 5 degree of freedom, i.e. 4 tracks from the same vertex - ≤100 tracks in the event

+- from J/

add ”+-” tracks

DDAfter CUT

- Use mass difference (to J/) for better resolution △M = M(+-+-) – M(+-) - data fit: (2S), Gaussian (solid) X(3872), Gaussian (solid) background, 3rd order polynomial (dashed)

- X(3872) candidates 522 ± 100 - mass difference 774.9 ± 3.1(stat) ± 3.0(syst) MeV/c2

- fitted width 17 ± 3 MeV/c2

Results:

DD X(3872) production and decay property studies: split data into two sub-samples with production variables:

b) Rapadity: - |y| ＜ 1 (central) - 1 ＜ |y| ＜ 2 (forward)

a) pT(J/) : - pT ＜ 15 GeV - pT ＞ 15 GeV

d) xy decay length dl (“prompt” or from B-decay): - dl ＜ 100 m - dl ＞ 100 m

DD c) Helicity Cos(), i.e. boost X and one of pions into di-pion rest frame and measuring the open angle: - Cos() ＜ 0.4 - Cos() ＞ 0.4

f) Helicity Cos(), i.e. boost X and one of muons into di-muon rest frame and measuring the open angle: - Cos() ＜ 0.4 - Cos() ＞ 0.4

e) Isolation, i.e. the ratio of X momentum to the sum of all tracks’ momentum in Cone 0.5 to X: - iso ＝ 1 , “isolated” - iso ＜ 1

spliting with decay variables:

DDpT

> 1

5 Ge

V|y

| <

1

Cos(

) <

0.

4

Cos(

) <

0.

4

isola

ted dl <

0.

01cm

The properties of production and

decay of X(3872) appears consistent

with (2S) within errors

For production/decay variables:- Calculate the ratio of one sub-sample to the total , eg N|y| ＜

1:Ntotal- Then compare X distribution with (2S) benchmark

DDWhat’s the X(3872)- Charmonium? L-excited multiplet splits much more than expected by assuming Coulomb-Scalar confinement

-“meson-molecule” ? M(D-+D*+)=3879.5±0.7MeV M(D0+D*0)=3871.5±0.5MeV (coincident?) appears unexpectedly narrow

DDSummary of X(3872):

- (522±100) candidates of signal are established with 230 pb-1 data- Selected production/decay properties of X(3872) are similar to those of (2S) within error

- Confirm the existence of X(3872) with mass difference

△M = M(X) – M(J/) = 774.9 ± 3.1(stat) ± 3.0(syst) MeV/c2

search for charged analog, X+J/+0

search for radiative decays

- Next step:

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The observation ofBc J/(+-) +

DD Bc -- last of ground state of meson

- The only previous evidence by CDF RunI

- Theory predictions: [1] C.Chang et al, PRD49(1994)3399 [2] E.Ebert et al, hep-ph/0401237; PRD68(2003)094020

MBc ~ 6.4 GeVBc ~ 0.3-0.5ps-- c~100m, significantly shorter than

B

Bc± J/(+-) ± -- Br~2.4% + trilepton final state + easy to trigger

DDEvents Selection:

- 210pb-1 data - di-muon triggered

- M(+-) within 0.25 GeV of J/

- a third track (pT>1.5) with best common vertex fit to J/() : “J/+1 track” data control sample

- The third “+1” track should be muon, with M(J/) ＜ 8 GeV

due to missing neutrals, the select samples are polluted by background severely

after Selection:

use () invariant mass and pseudo proper time distributions to fit

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Signal shape (MC): - MC templates of MBc 5.5 – 6.7 with 0.1GeV interval- Full detector smearing + Selection

Background shape (data): - use J/+1 track control data sample- divided into 2 subsets: 1) “prompt” J/ 2) “heavy flavor” one from B decay- cross-checked with(2S) + 1 track bkg dominated data

Bc Fit: extract signal from a combined unbinned likelihood fit to J/invariant mass and proper time

5.95 ±0.34 GeV+0.14

-0.13

Bc mass log likelihood

DD“Floating” fit signal + bkg distributions:

Signal 95.5±11.8Total 231

Prompt 66.0Heavy F 69.5

Number of events

With significance SB in excess of

5 standard deviations

DDConsistency check:

• Simple counting analysis - normalize background J/+1 track sample to selected sample with T>2

- check excess consistency with data

• Fit w/o signal 2log(likelihood)=60 for 5 degrees of freedom

DDSystematic uncertainties:

DDb

bcc

Bc

Something else:

-The associated c-quark likely results in a charmed hadron proximity to the Bc

- charmed mesons decay semileptonically occasionally

Test Probability of extra within ±90°:- J/+1 track background control sample, 1%- Selected Bc candidates, 5 out of 108, 5±2%

DDSummary:

Preliminary results on Bc with significantly more statistics

• Events: 95 ± 12±11• Mass: 5.95 ±0.34 GeV/c2 +0.14

-0.13

• Lifetime: 0.448 ±0.121 ps +0.123 -0.096

DD

The production of

Upsilon(1S)

DDTheory modeling of production:

- factorized QCD calculations to O(3) currently employed by Pythia- color-singlet, color-evaporation, color-octet models

(1S) Production @ Tevatron:- 50% produced promptly, i.e. at primary vertex and relatively isolated- 50% from excited states radiative decay

Event selection:- luminosity: 159.1 ± 10.3 pb-1

- di-muon: pT>3, tight Tracking and Calorimeter isolation cut- invariant mass in 7 – 13 GeV

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’s |y|

‘s P T

Data sample partition: - y1: 0 ＜ |y| ＜ 0.6 - y2: 0.6 ＜ |y| ＜ 1.2 - y3: 1.2 ＜ |y| ＜ 1.8

Sample fit: - Background: 3rd order polynomial - (1,2,3S) resonances: double Gaussian - the mass and width of (1S) are free parameters; others are fixed relative to the mass

DDEvaluating the (1S) Production Xsec:

with eff in different rapidity region:

The measured cross-section×BR((1S)) is as

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- No strong dependence on rapidity observed

749±20±75 781±21±78

598±19±56

with 6% luminosity uncertainty

DD

Run2 preliminary results consistent with CDF Run1

DDSummary:

measurements of production at D0 to 1.8 rapidity region

• The pT spectrum does not show significant difference in various rapidity region• Results consistent with CDF RunI’s - CDF √s=1.8TeV, |y|<0.4, d/dy*Br =680±15±18±26 pb - D0 √s=1.96TeV, |y|<0.6, d/dy*Br =749±20±75±49 pb - PYTHIA predict a factor of 1.11 from 1.8 to 1.96 TeV

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Thank you!

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