First (really significant) observation of at the Tevatron

1. First (really significant) observation of at the Tevatron Matthew Jones Purdue University B Production & Decay Subgroup

2. Bottomonium Spectroscopy B Production & Decay Subgroup

3. Cho & Leibovich, PRD 53, 6203 (1996). Octet Sum Singlet Motivation • Quarkonium production at hadron colliders is a mess: Amundson, Eboli, Gregores, Halzen, PL B390 (1997) 323-328. PRL 79, 572 (1997)

4. Motivation • Quarkonium production at hadron colliders is a mess: Even if the cross section problem can be fixed, a good description of polarization at high pT remains elusive... Braaten & Lee, PRD 63, 071501R ( 2001)

5. Motivation • Quarkonium production at hadron colliders is a mess: |y| < 1.8 |y| < 0.6

6. Motivation • Many possible issues – I will discuss only one of them: • Polarization of ϒ(1S) depends on feed-down from excited states like • How much is there? Assumed to be 27% and 11%, respectively... These came from a CDF measurement in Run I.

7. NRQCD predictions for ϒ(1S) polarization need input for feed-down from . states. 3.3 and 2.3σ effects... Might not be called an “observation” by today’s overly rigorous standards. But these states dilute the longitudinal polarization predicted by NRQCD... Feed-down? CDF Run I PRL 84, 2094 (2000) B Production & Decay Subgroup

8. This Analysis • Reconstruct • Reconstruct • Look for peak in the distribution of • Not a blind analysis, but avoid introducing any selection bias. B Production & Decay Subgroup

9. Di-muon data sample • Runs 138425 – 277511 (periods 1-25) • Datasets: jbmm0[dhijkm] • Prereq on L3TriggerNames: • UPSILON_CMUP_CMU • UPSILON_CMUP_CMX • After stripping: • Confirm trigger bits • Good run list: goodrun_em_mu_nosi_v31 B Production & Decay Subgroup

10. Monte Carlo Samples • Generated a bunch of • Generated using: This is a bit of an unfortunate choice. Generation of new Monte Carlo is underway... Decayed using only phase space model so we can reweight later... B Production & Decay Subgroup

11. Upsilon Reconstruction • After loose selection using CharmMods: • Tracks matched with XFT tracks • Require CMUP+CMU or CMUP+CMX depending on which trigger bit was set • Require pT > 4 GeV/c for CMUP • Require pT > 3 GeV/c for CMU/CMX • Require pT(μ+μ-) > 4 GeV/c • Fit to a common vertex • Still need to apply sensible muon fiducial cuts B Production & Decay Subgroup

12. Upsilon Reconstruction B Production & Decay Subgroup

13. Di-muon mass fit • Yields of ϒ(1S) needed for relative efficiency calculation and pT reweighting. • A crystal ball function seems better than a bunch of Gaussians... • Assume measured mass splitting differences, allow for an overall shift • Single Gaussian resolution parameter • 4th order polynomial background function B Production & Decay Subgroup

14. Di-muon Mass Fit B Production & Decay Subgroup

15. Momentum Spectrum CDF Data (oops) B Production & Decay Subgroup

16. Conversion Reconstruction • Loop over oppositely charged tracks • Skip the muons • Require at least 20 COT hits • With Δφ(track,ϒ candidate) < 45° • Determine point at which circles are cotangent in the r-φ plane and calculate • Constrain the tracks to a common point in z at the cotangent point and calculate Δcot θ • Lots of geometric quantities that can be used to optimize the selection of conversion candidates. B Production & Decay Subgroup

17. A First Look • An initial set of “sensible” cuts: • pT(μ+μ-) > 15 GeV/c (to boost the photon) • 9.35 < M(μ+μ-) < 9.55 GeV/c2 • |Sxy| < 1 cm, |Δcot θ| < 0.2, |Δz| < 2 cm • r > 10 cm, |d0(e±)| > 0.05 cm • Likelihood(μ±) > 0.5 • Take a look... B Production & Decay Subgroup

18. A First Look • Not much of a signal, but it was very robust with respect to varying the cuts. B Production & Decay Subgroup

19. Optimization Procedure • Absolute efficiency not needed for optimization • Relative efficiency for muon selection from ratio of ϒ(1S) yields. • Relative efficiency for conversions determined from Monte Carlo sample • Background from fit to Δm distribution, excluding signal windows. • Maximize wrt x. B Production & Decay Subgroup

20. Example background fit • Binned likelihood fit to an Argus function: 770-820 MeV/c2 400 – 470 MeV/c2 B Production & Decay Subgroup

21. Optimized Selection • Optimized selection sequentially • Correlations are generally small • Avoided variables sensitive to pT spectrum B Production & Decay Subgroup

22. Optimized Selection My guess is that the 1P states have significance > 5σ. Not sure about the 2P states... B Production & Decay Subgroup

23. Next... • Just observing these states is fun but not particularly useful... • What we need is: • Absolute production cross sections • Cross sections relative to ϒ(1S) • Relative production fractions • Production polarization • Establish spins of the P-wave states • Doing even one of these would be useful. B Production & Decay Subgroup

24. Next Steps • Generate better Monte Carlo samples: |η| < 2, 4 < pT < 60 GeV, higher statistics • Reweight pT spectrum to match ϒ(1S) spectrum. • Better muon fiducial definition to help match data/Monte Carlo • Kinematic fit to decay topology • Even more variables available for optimization • Optimize selection for the 2P states • Fit signals and measure yields • Do helicity amplitude analysis to reweight Monte Carlo for an acceptance calculation. • There might be a way to measure conversion finding efficiency in data... B Production & Decay Subgroup