inclusive production at y(1s) sheldon stone jianchun wang syracuse university cleo meeting 09/13/02

Inclusive Production at Y(1S)

Sheldon StoneJianchun Wang

Syracuse University

CLEO Meeting09/13/02

09/13/02 Jianchun (JC) Wang 2

Motivation

B (B X) measurements with P > 2 GeV, where background from bc processes are suppressed:

CLEO: PRL 81,1786(1998),

BaBar:

A majority of events lie at large recoil mass (M>1.8 GeV) .

Atwood & Soni proposed that the large yield is associated with the gluonic content of the via the sub-process bs(gg). The form factor remains constant up to q2 mb

2 (momentum transfer of g ). This explains the large recoil mass and large yield ( B ~ 810).

40.01.5(6.2 1.6 1.3 ) 10

40.7 0.0

1.0 0.5(6.8 1.0 ) 10


Motivation Hou and Tseng suggest that s be running and evaluated at

the scale of momentum transfer through the gg vertex, which introduces a mild logarithmic suppression (slowly falling):

The pQCD predicts that the leading form factor contribution falls like 1/q2 (by Kagan & Petrov). The form factor can be parameterized as (pQCD):

KP also construct a purely phenomenological form factor for comparison (intermediate):

2'

52 2 20 ' 3( ) 10,H q H m q m B

2 2 42( ) 1 , 2.2 , 4.4 10BH q q M M GeV

42 2 2'( ) ( ) / 6.8 10( ), .s sH q q m B


Motivation

Y(1S) gg(gg): large overlap on the region of q2 relevant for fast production with that in bs(gg).

A. Kagan: “ the spectrum in Y(1S) decay could potentially constrain the gg form factor, and at the same time tell us if the sub-process bs(gg) can account for the yield in B decay”.

ARGUS measurement (w/o continuum subtraction) extracted by Kagan to be: nZ>0.7 < (6.51.3)10.

Model prediction:

0.7

41

1

13

theory

argus z

slowly fallingn

pQCDn

intermediate


Reconstruction of

Photon: E > 30 MeV | cos | < 0.707 E9/E25 Not fragment Angcrt > 20

: (Mass constraint) Multi-bump cut Mass cut: –3.0 to 3.0

Track: TNG approval Good primary track Impact point (0.005,0.03 for

p>0.25, 0.01,0.05 for p<0.25) 3 dE/dX consistence

: For Z<0.5, veto on

photons

(B =44.3%) B =39.3%)

Z = E/Ebeam


The Invariant Mass Spectraa) Y(1S) data (~80 pb) : 1S13 ( 1.862106 Y(1S) )

b) Continuum data (~1200 pb): 4S27, EG

a) b)

N = 1486137 N = 4062174


The Invariant Mass Spectra

Z > 0.7

a) b)

N = 41 7 N = 241 20


Signal Sources

The sources of production in 1S data: qq X: ~ 4 nb

2) Y(1S) qq X: ~ 2 nb

3) Y(1S) ggg X: ~ 18 nb

4) Y(1S) gg X: ~ 0.5 nb

Use qq and ggg generator respectively

The gg is treated as ggg throughout the study


Breakdown of Signal Events

(1 ) (1 ) *

(1 ) (1 ) * ,10.52 * * ,10.52

all S ggg S qq qq

S ggg S qq qq qq qq

N N N N

N f N f N

Number of Signal before efficiency correction

*

29.46 9.46

210.52 10.52

( ) ( ) ( ' ) ( )

80.4 1/ 9.460.9356 0.0780

1192.9 1/10.52

qq QCDf f luminosity f f production f efficiency

(1 ) 9.46(1 ) *

10.52*

0.0387SS qq qq

Rf f

R


Z Mapping for Continuum DataFor continuum data, Z= E/Ebeam is not good, it needs remapping

Simple one: Linear with Zmin(10.52) Zmin(9.46), 11

Sophisticated one:10.52 9.46' '

10.52 9.460 0( ) ( )

Z Zp z dz p z dz

0.202

0.182

P4 fit


Reconstruction Efficiency

Event shape is more spherical in 3g event: 3g/qq,9.46 ~ 1.15

Event is more jetty at 10.52 GeV: qq,10.52/qq,9.46 ~ 0.93

Beam energy also affects production: nqq,10.52/nqq,9.46 ~ 1.07

No veto With veto


Y(1S) data ° veto applied for Z < 0.5. Mass fixed to average over all Z. Width determined from MC.


Off-resonance data ° veto applied for Z < 0.5. Mass fixed to average over all Z. Width determined from MC.


Breakdown of Signal Events

The total number is the sum of small Z bins. Z-dependent reconstruction efficiency used.

24.5 8.11145 120 Y(1S) ggg,qq

21.5 1.4349 11 Continuum qq

10.6 0.7173 5 Y(1S) qq

13.9 8.1972 120 Y(1S) ggg

257.1 17.34294 130 Off-resonance

46.0 8.11494 120 Y(1S) data

Z > 0.7All Z Sample


Branching RatioInclusive branching fraction for All Z:

Inclusive branching fraction for Z > 0.7:

At 90% C.L. the upper limit of B (Y(1S)(ggg) X) / B(Y(1S)(ggg)) for Z > 0.7 is 3.4

B (Y(1S)X)

B (Y(1S)(ggg) X) / B(Y(1S)(ggg))

B (Y(1S)(qq)X) / B(Y(1S)(qq))

B (Y(1S)X)

B (Y(1S)(ggg) X) / B(Y(1S)(ggg))

B (Y(1S)(qq)X) / B(Y(1S)(qq))


Systematic Errors

Total systematic error

Z mapping

Y(1S)

Ratio of integrated luminosity

B (Y(1S)qq)

B

Total number of Y(1S)

Number of from fit

Reconstruction efficiency of

Reconstruction efficiency of

All othersqq Sampleggg Sample (Z>0.7)

Sources


The Differential Branching Fraction

Systematic errors are not shown ( ~ 10%).

Detailed study on excess at 0.6<Z<0.7 reveals no narrow structure (corresponding to 5.3 < Mrecoil < 6.1 GeV ). There could be more than one processes.

(1 ) ( ) '

(1 ) ( )

d S ggg X

dZ S ggg

B

B

(1 ) ( ) '

(1 ) ( )

d S qq X

dZ S qq

B

B (1 ) 'd S X

dZ

B

?!


Comparison with Theoretical Predictions

The measured dn/dZ spectrum of Y(1S)(ggg) X.

Theoretical predictions with

a) A slowly falling form factor.

b) A rapidly falling form factor.

c) An intermediate form factor.

The measurement favors rapidly falling q2 dependence of the g*g form factor predicted by pQCD.


Summary

We measured the inclusive production rate from Y(1S) data and ggg, qq samples.

Small B (Y(1S)X) at high energy strongly favors rapidly falling q2 dependence of the gg form factor predicted by pQCD.

CBX 02-09 ready for comment.


Z Spectra Generated

Z redefined for 10.52 GeV qq data


Signal Reconstructed

° veto applied

for Z < 0.5


Breakdown of Z Spectrum


Cross-section and Branching Fraction Sources:

1. PRD39, 3528 (1989), CLEO (muonic branching fractions at 1S and 3S). ((1S) 1.12 nb (by QED) (Y(1S) (0.5550.022) nb (Y(1S)hadrons (20.390.04) nb Br(Y(1S)0.07 0.07)%

2. PRD57, 1350 (1998), CLEO (hadron cross section at 10.52 GeV). R 3.560.01 0.07

3. PRD55, 5273(1997), CLEO (direct photon spectrum at 1S). (Y(1S)gg )/ (Y(1S)ggg) (2.75 0.04 0.15)%

4. RPP2000. Br (Y(1S))% Br (Y(1S)ee0.11)% Br (Y(1S)0.06)%

Calculation here qq) (1.123.56) (3.990.08) nb (Y(1S)qq) (0.5553.56) (1.980.09) nb 3) Br(Y(1S)qq) (2.483.56) (8.830.28)% (Y(1S)ggg/) (20.391.98) (18.410.09) nb5) Br(Y(1S)ggg/ (Y(1S)ggg) (17.920.09) nb (Y(1S)gg( 0.490.03) nb

inclusive production at y(1s) sheldon stone jianchun wang syracuse university cleo meeting 09/13/02

Documents

jianchun jc wang7

jianchun jc wang13

y1s data z

z sample slide

jianchun jc wang10 z

continuum qq

study slide

g g form factor