Paper Committee:

Moneti(chair?), Danko, Ehrlich, Galik

1 OCT 21, 2006

History/Bibliography:Most germane previous CLEO publication:Direct Photon Spectrum from Upsilon(1S),Upsilon(2S) and Upsilon(3S) Decays Phys. Rev. D 74, 012003 (2006)

Last plenary presentation by Shawn at Sept. meeting (almost Nochanges since.

Conference paper:Measurement of Upper Limits for Upsilon to gamma + Resonance Decays, J. Rosner et al. Presented at 33rd International Conference on High Energy Physics, July 26- August 2, 2006, Moscow (ICHEP06) hep-ex/0607054

CBX, Draft at http://w4.lns.cornell.edu/restricted/draft/..Y_GammaRes_CBX.ps( or PDF), Y_GammaRes_PRD.ps( or PDF)

Intended for PRD publication

2 OCT 21, 2006

3 OCT 21, 2006

Motivation

s extraction in gg analysis:

Exp’t and theory assume a continuous direct photon spectrum in determining BR(Y—> gg)/BR(Y—> ggg)

• Two-body radiative decays comprise a systematic uncertainty in gg analysis (“bumps” in gamma spectrum!)

• This is especially true near the kinematic end-point (x ~ 1,

low M). We DO see (small) Y—> + f2(1270)

• Resonant enhancements could explain why estimates of s

from decays are systematically lower than the world average

4 OCT 21, 2006

Look for a Resonance Signal

Above suggests a search for + , 4 charged tracksusing same hadronic event selection as published ggg analysis.

• A two-body radiative decay will produce a monochromatic in the lab frame, leading to ''bumps'' in the otherwise smooth predicted theoretical ggspectrum.

• Goal: try to determine upper limits on (narrow)resonance contribution to gg rate.

• Complication: bkg’d (ISR + hadron fakes) NOT subtracted

5 OCT 21, 2006

MC Example: BIG SIGNAL !

Brief Analysis Orientation

Remember:

• XE/Ebeam , M(res) = 2Ebeamsqrt(1- X)

For Y(1S), X = 0.2 means M ~ 1 GeV, (E) ~ 20MeV X= 0.9 means M ~ 4.3 GeV, (E) ~ 60MeV

We can be largely sensitive to resonances of ~ this width or narrower. Fixed resolution at each X

1) step along X -spectrum in steps of 0.5 (E) , taking a ± 10 range of X X in which to fit for gaussian signal on polynomial background; bin size is 0.2*

2) Extract Area, A(X )of gaussian at each step, plot.

6 OCT 21, 2006

Method (cont.)

3) Convert to upper limit contour with height=A(x)+1.645*A(x) where A(x) is the gaussian fit area sigma.

4) Negative points 1.645*A(x)

5) Study continuum data, too. Look for evidence of bumps common to Y(nS) and continuum. ''etc…?

6) apply estimate (conservative) of efficiency to give BR limits.

7) We use efficiency and 0- (or 0+) 1+cos2 for angular distribution.

8) re-plot with MR as abcissa

7 OCT 21, 2006

8 OCT 21, 2006

Y(1S)

Y(1S) binned vs. MR

9 OCT 21, 2006

Efficiency corrected BR’s

10 OCT 21, 2006

Y(1S), scaled <Y(1S) comparison

Correlated? ISR?

11 OCT 21, 2006

12 OCT 21, 2006

Monte Carlo Check

Easy way to check procedure: input known *+, 4 MC signal at various sensitivities and check that which we reconstruct reliably.

In this check, we construct all signals above our upper limit floor (~10-4) within our accessible recoil mass range

See Plot

13 OCT 21, 2006

if >BR 10-4

then recovered

MC with 10 embedded R’s

14 OCT 21, 2006

Our sensitivity is of order 10-4 across all accessible values of M

• We measure for all M:

B((1S)+,4 charged tracks) < 1.26 x 10-3

B((2S)+,4 charged tracks) < 9.16 x 10-4

B((3S)+,4 charged tracks) < 9.69 x 10-4

B((4S)+,4 charged tracks) < 1.21 x 10-3

If more restrictive in M1.5GeVM 5GeV we do better.

Result Summary (1)

15 OCT 21, 2006

B((1S)+,4 charged tracks) < 1.78 x 10-4

B((2S)+,4 charged tracks) < 1.95 x 10-4

B((3S)+,4 charged tracks) < 2.20 x 10-4

B((4S)+,4 charged tracks) < 5.34 x 10-4

• We report these upper limits as a function of recoiling mass M

• B.R.’s are all ~10-4 :unlikely to impact decays in gg analysis

Result Summary (2)

Systematic Matters

We currently assess the following systematics:

Exclusive decay channel uncertainty: we take the worst correction imaginable Luminosity uncertainty: for continuum measurements, we assess a uniform 1% correction (determined in gg analysis) Total # events uncertainty: we take the total number of events to be Nevents() -1events

Systematic fitting uncertainty: We bin our fitted spectra in 5 bins/signal width and use a 4th order Chebyschev, based on studies of our procedure applied to continuum. Noimpact of polynomial order or binning.

16 OCT 21, 2006

17 OCT 21, 2006

Method (Efficiency Subtleties)

• To be conservative, 2 restrictions on the mode we obtain our

M-dependent correction function from:• We only consider modes with 4 charged tracks in the final state (should have lowest ’s due to multiplicity cut)• We take as our the worst plausible

• We generate 5K events dedicated to each mode, and average the efficiency from

1.0 GeV < E < 4.5 GeV

(backup #1)

18 OCT 21, 2006

Efficiencies (*+, →?)

602%460545%2p20

572%440652%4p0

543%22K20482%4K0

572%2p2K20602%40

635%2p220533%22K632%4p20562%2p2K

524%6p492%4K20623%2p2684%6K591%420672%4p743%6532%22K0502%4K602%480505%2p2K0592%4

Worst

Phase Space

High Mult.

19 OCT 21, 2006

Worst possible efficiency vs. E