σEγ comparison using

Woochun Park

Univ of South Carolina

Feb 26, 2005

@EMC

Photon energy resolution (BaBar Note# 583)

• σγ has more than an estimate of photon energy resolution since it includes track momentum uncertainty.

• We subtract this effect in quadrature after estimating:

• We are not able to distinguish Xc1 and Xc2, so

• ΔM (Mχ ci- MJ/ψ) < 0.447: MPDGχc =MPDGxc1

else MPDGχc =MPDGxc2.

(Need to study about σEγ dependence on χci . More ideas in page 8-9.)

Selecting samples• Following BAD#139, “Inclusive charmonium state analysis in B”• Analysis 23 (14.5.5) SP5 MC• Jpsitoll skim:AllEvents: 2.25%; B0B0b: 4.78%;B+B-: 5.36%; ccb: 5.67% • For J/ψ (only for μμ today):

– With radiation recovery. Selectors are not decided yet.– One “Tight” muon and one “Very Tight” muon (cut opt. in next page).– Geometric constraint on vertex.– p*J/ψ < 2.0 GeV/c, Mee is not decided. and 3.06 < Mμμ < 3.13 GeV.

• For χc1,2:– GoodPhotonLoose List– Zernike(4,2) moment < 0.15– Reject photons from π0 candidate with no constained mass b/w 0.117

and 0.147, Emin = 30MeV, Lat < 0.8– 0.12 < Eγ < 1.0 GeV– To suppress hadronic split-offs, photon should be at least 9 degree

from any charged tracks.– p* < 1.7 GeV/c

J/ψ→μμ Optimization• For each muNN cuts, estimate signal and background with all cuts

applied in signal window, 3.06 < Mμμ < 3.13 GeV. Run1 data used.

• (muNNTight, muNNVeryTight) is selected based upon S2/B.

muNN Signal BG S/B S2/B

VL VL 17257.6 / 190.134 12986.4 / 1611.61 1.33 22934

VL L 17198.6 / 191.597 12246 / 1564.99 1.40 24154

VL T 16788.1 / 179.556 9826.95 / 1401.92 1.71 28680

VL VT 16200.7 / 172.565 8587.19 / 1310.51 1.89 30564

L L 15414.6 / 167.639 8001.1 / 1265 1.93 29697

L T 15250.4 / 163.102 7181.98 / 1198.5 2.12 32383

L VT 14815.2 / 158.366 6495.07 / 1139.74 2.28 33793

T T 12418.3 / 139.561 4301.81 / 927.557 2.89 35849

T VT 12261.5 / 138.222 4175.4 / 913.827 2.94 36007

VT VT 9771.77 / 121.703 3047.39 / 780.691 3.21 31334

Off-resonance(error) vs cont MC(line)

Offdata = 56±7.5 (2.35 fb-1)contMC = 50.1±2.7

Ratio = 1.12 ± 0.16

Using J/ψ → μ μ (Run1)

• Muon efficiency correction would make them more inconsistent.• There is no clear peak from continuum BG. Easy to model BG shape.• Shapes are consistent b/w OnPeak & BBMC.

On-resonance(error) vs MC(line)

Ondata = 7692±88(19.5 fb-1)BBMC+scaled Offdata = 5892±77

Ratio = 1.31 ± 0.02

Life becomes simple if data is

like this!!!

Etrue

Emeas Ecalc

MC

DATA

For all Emeas spectrum

(50MeV binnings will be in next page)

• Divide Emeas by 50MeV from 200MeV and 800MeV. Fit each plot with Gaussian+Pol1.

• Subtract track momentum uncertainty in quadrature.

BB MC

DATA

Next page

RESULT• Data and MC looks consistent except [400, 450] MeV in Emeas.• More statistics come from J/ψ→ee. • Ntuple generations are very smooth. Higher priority on batch

queue usage will definitely help me to get faster results.

RUN2 D*->D0 gamma

[400, 450]

Emeas

Emeas

DATA

MC

DATA

MC

DATA

σEγ dependence on Mχc1,2

• Assuming that we mis-assign Xc1 mass to Xc2 (Xc2 decay width (2.11±0.16 MeV) is about twice bigger than Xc1 (0.91±0.13 MeV). )

– ΔMXc = -46MeV (MXc1 = 3510.59 MeV : MXc2 = 3556.26 MeV )– δEcalc~ -2 (ΔMXc) MXc ≈ -0.325 GeV2

– MXcPDG 2 - Mψ

PDG 2 ≈ 2.85 GeV2

– δEcalc ≈ -0.11 Ecalc (mis-assignment causes 11% error in Ecalc per event.)

– δσEγ = -0.11/ Ecalc ≈ -25% per event when Ecalc = 0.44 GeV

• If we are confused in DATA as much as MC, it’s just fine on the purpose of measuring relative photon energy resolution.– We need to estimate how much different mis-assignment rate

between MC and DATA.– Maximum likelihood fit on σEγ and R(Yxc1/Yxc2) could be one

alternative way. R measurement could be a physics topic, “inclusive Xc braching ratio analysis”.

Very preliminary Study on R (Run1) – eMicroVeryTight and eMicroTight w/o radiation recovery electron.– muMicroTight and muMicroLoose– 3.05 < Mee < 3.12 and 3.07 < Mμμ < 3.12 GeV.– Fit with Gaussian + Pol2

Signal MC BB MC OnData

R=2.46 ± 0.07(sigMC) R=4.06 ± 0.75 (BB MC) R=11.6 ± 4.7(OnPeak)

PDG R= 4.54 ± 1.59

More presentation is advisedat EMC software/calibration meeting

tomorrow.

Δ(σEγ)

Δ(δσEγ)

X-axis is Ecalc (page 8 has Emeas x-axis)

δσEγ /Ecalc

σEγ/Ecalc

DATA

MC

DATA

MC

J/ψ →μμ Run1

To-do• Move on to Run4 to take advantage of the best statistics dataset.• Simulate combinatoric background.

• study about σEγ dependence on χci

• μ efficiency correction to compare MC with DATA.

Question• How to include μ efficiency correction??

• With 2 month-old in BaBar, it’s very difficult to find.– I tried ntpBlockContents set "mu : Momentum CMMomentum MCIdx PIDWeight(muNNTight)“

– It only gives me 1.0 weight and 0 status all the time which doesn’t see to reasonable.

– Then, I include pidCfg_mode tweak * and pidCfg_mode weight * – But, my BtaTupleApp doesn’t recognize pidCfg_mode command.