CaltechTHESIS
  A Caltech Library Service

A Study of Charged D* Mesons Produced in e⁺e⁻ Annihilation at E꜀ₘ = 29 GeV

Citation

Yamamoto, Hitoshi (1986) A Study of Charged D* Mesons Produced in e⁺e⁻ Annihilation at E꜀ₘ = 29 GeV. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/nms8-7v38. https://resolver.caltech.edu/CaltechTHESIS:04152019-093410294

Abstract

Charged D* mesons produced in e+e- annihilation at a center-of-mass energy of 29 GeV have been studied with the DELCO detector at the PEP storage ring. The selection criteria of D* candidates exploit the π/K separation capability in the momentum range from 2.6 GeV/c to 9.2 Ge VIc provided by the gas Čerenkov counter. The data correspond to an integrated luminosity of 147 pb-1.

We have measured the total production cross section of D*± to be [0.16±0.02(statistical)±0.02(systematic)] nb [x ≡ PD*/(E2beam-M2D*)1/2 > 0.35], and (0.18 ± 0.02 ± 0.03) nb (x > 0) if the contribution from bottom quarks is subtracted. The branching fractions used are Br(D*+ → D0π+) = 64% and Br(D0 → K-π+) = 3%. The systematic errors due to the branching ratios are not included in the errors. With Br(D0 → K-π+) = 4.9%, which is a recent measurement by the MARK III group, the above two cross sections become 0.10±0.02±0.02 nb (x > 0.35) and 0.11±0.02±0.02 nb (x > 0 and after the subtraction of the contribution from b quarks).

The charm fragmentation function is harder than that for light quarks, and the shape is found to be consistent with the prediction of the string model with a uniform string-breaking probability. Assuming the string model, the string-breaking probability is determined to be (0.019 ± 0.05 ± 0.09) GeV2.

We have also determined the lifetime of D0 meson which is detected in the D* decay, with the result τD0 = (5.3 ± 1.7+0.6-0.5) x 10-13 sec. Together with the semileptonic branching fraction of D0 measured elsewhere, the semileptonic decay rate of D0 is estimated to be (1.4 ± 0.5) x 1011 sec-1, which corresponds to an effective charm quark mass of (1.54 ± 0.12) GeV/c2.

Using part of the D* candidates, we have set an upper limit on D0-D̅0 mixing: r ≡ P(D0 → D̅0)/P(D0 → D0 or D̅0) < 8.3% (90% c.l.), leading to a stringent limit on charm-changing neutral currents.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Physics
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Barish, Barry C.
Thesis Committee:
  • Barish, Barry C. (chair)
  • Hitlin, David G.
  • Wise, Mark B.
  • McKeon, Beverley J.
  • Gottshalk, Thomas D.
Defense Date:26 November 1985
Additional Information:Thesis title listed in 1986 Commencement Program varies from actual thesis: A Study of Charged D* Mesons Produced in e⁺e⁻ Annihilations at E꜀ₘ = 29 GeV.
Record Number:CaltechTHESIS:04152019-093410294
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:04152019-093410294
DOI:10.7907/nms8-7v38
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11460
Collection:CaltechTHESIS
Deposited By: Melissa Ray
Deposited On:15 Apr 2019 17:54
Last Modified:16 Apr 2021 23:07

Thesis Files

[img]
Preview
PDF - Final Version
See Usage Policy.

65MB

Repository Staff Only: item control page