Inclusive Production at Y(1S) Sheldon Stone Jianchun Wang Syracuse University CLEO Meeting 09/13/02.
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Inclusive Production at Y(1S) Sheldon Stone Jianchun Wang Syracuse University CLEO Meeting 09/13/02
Jianchun (JC) Wang2 Motivation B (B X) measurements with P > 2 GeV, where background from b c 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 b s(g g ). The form factor remains constant up to q 2 m b 2 (momentum transfer of g ). This explains the large recoil mass and large yield ( B ~ 8 10 ).
09/13/02Jianchun (JC) Wang3 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/q 2 (by Kagan & Petrov). The form factor can be parameterized as (pQCD): KP also construct a purely phenomenological form factor for comparison (intermediate):
09/13/02Jianchun (JC) Wang4 Motivation Y(1S) gg(g g ): large overlap on the region of q 2 relevant for fast production with that in b s(g g ). A. Kagan: “ the spectrum in Y(1S) decay could potentially constrain the g g form factor, and at the same time tell us if the sub-process b s(g g ) can account for the yield in B decay”. ARGUS measurement (w/o continuum subtraction) extracted by Kagan to be: n Z>0.7 < (6.5 1.3) 10 . Model prediction:
09/13/02Jianchun (JC) Wang5 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 /E beam
09/13/02Jianchun (JC) Wang6 The Invariant Mass Spectra a)Y(1S) data (~80 pb ) : 1S1 3 ( 1.862 10 6 Y(1S) ) b)Continuum data (~1200 pb ): 4S2 7, E G a)b) N = 1486 137N = 4062 174
09/13/02Jianchun (JC) Wang7 The Invariant Mass Spectra Z > 0.7 a) b) N = 41 7N = 241 20
09/13/02Jianchun (JC) Wang8 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
09/13/02Jianchun (JC) Wang9 Breakdown of Signal Events Number of Signal before efficiency correction
09/13/02Jianchun (JC) Wang10 Z Mapping for Continuum Data For continuum data, Z= E /E beam is not good, it needs remapping Simple one: Linear with Z min (10.52) Z min (9.46), 1 1 Sophisticated one: 0.202 0.182 P4 fit
09/13/02Jianchun (JC) Wang11 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: n qq,10.52 /n qq,9.46 ~ 1.07 No vetoWith veto
09/13/02Jianchun (JC) Wang12 Y(1S) data ° veto applied for Z < 0.5. Mass fixed to average over all Z. Width determined from MC.
09/13/02Jianchun (JC) Wang13 Off-resonance data ° veto applied for Z < 0.5. Mass fixed to average over all Z. Width determined from MC.
09/13/02Jianchun (JC) Wang14 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
09/13/02Jianchun (JC) Wang15 Branching Ratio Inclusive 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))
09/13/02Jianchun (JC) Wang16 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
09/13/02Jianchun (JC) Wang17 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 < M recoil < 6.1 GeV ). There could be more than one processes. ?!
09/13/02Jianchun (JC) Wang18 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.
09/13/02Jianchun (JC) Wang19 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 q 2 dependence of the g g form factor predicted by pQCD. CBX 02-09 ready for comment.
09/13/02Jianchun (JC) Wang20 Z Spectra Generated Z redefined for 10.52 GeV qq data
09/13/02Jianchun (JC) Wang21 Signal Reconstructed ° veto applied for Z < 0.5
09/13/02Jianchun (JC) Wang22 Breakdown of Z Spectrum