D Meson Production In Ee Annihilation 3 7 To 7 0 Gev Total Cross Section Branching Ratio PDF Download
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Release | : 1979 |
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Download D Meson Production in Ee− Annihilation. [3. 7 to 7. 0 GeV, Total Cross Section, Branching Ratio]. Book in PDF, ePub and Kindle
The production of D mesons in ee− annihilation for the center-of-mass energy range 3.7 to 7.0 GeV was studied with the MARK I magnetic detector at SPEAR. A resonance was observed in the total cross section for hadron production in ee− annihilation at an energy just above the threshold for charm production. This resonance, which is named psi'', has a mass of 3772 +- 6 MeV/c2, a total width of 28 +- 5 MeV/c2, a partial width to electron pairs of 345 +- 85 eV/c2, and decays almost exclusively into D anti D pairs. The psi'' provides a rich source of background-free and kinematically well defined D mesons for study. From produced in the decay of the psi'' the masses of the D° and D/sup +/ mesons were determined to be 1863.3 +- 0.9 MeV/c2 and 1868.3 +- 0.9 MeV/c2 respectively. Also the branching fractions for D° decay to K−.pi./sup +/, anti K°.pi./sup +/.pi.− and K−.pi./sup +/.pi.−.pi./sup +/ were determined to be (2.2 +- 0.6)%, (4.0 +- 1.3)%, and (3.2 +- 1.1)% and the branching fractions for D/sup +/ decay to anti K°.pi./sup +/ and K−.pi./sup +/.pi./sup +/ to be (1.5 +- 0.60)% and (3.9 +- 1.0)%. The average number of kaons per D decay was found to be 0.52 +- 0.14 K°'s and 0.42 +- 0.12 K/sup +/'s. The rate for inclusive production of D mesons at center-of-mass energies above the psi'' was measured; it is found that it can account for most, if not all, of the observed increase in the total hadronic cross-section for center-of-mass energies above 4 GeV. The inclusive momentum and energy spectra for D's were measured at the highest available center-of-mass energy (7 GeV). The energy spectra are rapidly decreasing functions of energy with a slope similar to the slope of the charged pion spectrum at the same center-of-mass energy. This behavior suggests that the fragmentation function of the charmed quark into charmed mesons is a decreasing function of the scaling variable z = 2E/sub D//E/sub CM/. 81 references.
Author | : Petros-Afentoulis Rapidis |
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Total Pages | : 228 |
Release | : 1979 |
Genre | : Annihilation reactions |
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Download D Meson Production in E+e− Annihilation Book in PDF, ePub and Kindle
Author | : |
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Total Pages | : 680 |
Release | : 1976 |
Genre | : Nuclear energy |
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Download Nuclear Science Abstracts Book in PDF, ePub and Kindle
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Total Pages | : 1684 |
Release | : 1988 |
Genre | : Power resources |
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Download Energy Research Abstracts Book in PDF, ePub and Kindle
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Release | : 1980 |
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Download Inclusive D Meson Production with the Mark II Detector at SPEAR. [3. 9 to 7. 4 GeV (c. M.)]. Book in PDF, ePub and Kindle
Neutral and charged D meson production cross sections were measured at center-of-mass energies between 3.9 GeV and 7.4 GeV. The quantity R/sub D/(=(sigma/sub D+D−/ + sigma/sub D°+ anti D°/)/2 sigma/sub ..mu ... mu..−/) is equal to 2 at 4 GeV and 4.4 GeV and about equal to 1 elsewhere. R/sub D/ + 2.5 approximately equals R (sigma/sub hadrons//sigma/sub ..mu..+..mu..−/) at all energies. The exclusive cross sections for e+e− annihilation into D anti D, D* anti D, and D* anti D* were measured at center-of-mass energies between 3.9 GeV and 4.3 GeV. sigma/sub D* anti D*/ decreases with increasing center-of-mass energy from 6.6 +- 1.3 nb near 4 GeV to 3.6 +- 9 nb near 4.3 GeV. sigma/sub D* anti D/ also decreases from 4.2 +- 9 nb to 1.8 +- 6 nb over the same energy region. sigma/sub D anti D/ is less than 0.5 +- 3 nb at all energies. The branching fractions for D*/sup +/ and D* decay were measured. B/sub D*°..-->..D°..pi..°/ = 0.5 +- 09, B/sub D*/sup +/..-->..D°..pi../sup +// = 0.44 +- 10, and B/sub D*/sup +/..-->..D/sup +/..pi..°/ = 0.31 +- 07. At 5.2 GeV, the D meson differential cross section is well described by phase space for e/sup +/e− ..-->.. D anti D..pi pi.. or D* anti D*..pi pi ... Sd sigma/dz was parameterized as A(1-z)/sup n/ with n = 0.9 +- 4. Quasi-two-body production accounts for less than 20% of the total D cross section. No evidence was found for associated charmed baryon-D meson production. An upper limit of 0.4 nb (90% confidence level) was determined for associated production. 41 figures, 12 tables.
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Total Pages | : 640 |
Release | : 1992 |
Genre | : Nuclear physics |
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Download Soviet Journal of Nuclear Physics Book in PDF, ePub and Kindle
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Release | : 2004 |
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Download A Measurement of D+ and D(s) Production in E+ E- Annihilation at S** 1/2 Book in PDF, ePub and Kindle
Measurements have been made of the production rates of D[sup +] and D[sub s] mesons via the channels D[sup +]-[bar K]*[sup 0] [ell][sup +][nu][sub [ell]] and D[sub s] [yields] [phi][pi] in e[sup +]e[sup -] annihilation at [radical]s = 29 GeV in 220 pb[sup -1] of data collected by the Mark II detector. The measurements assume the current branching ratios, measured predominantly at [radical]s [approx-equal] 10 GeV and by fixed target experiments. Measurements of the total production cross-sections times the appropriate branching ratios, which are independent of any other measurements, and an upper limit for the ratio of branching ratios, [Lambda](D[sub s] [yields] [phi][ell][bar [nu]][sub [ell]])/[Lambda](D[sub s] [yields] [phi][pi])
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Total Pages | : 1146 |
Release | : 1994 |
Genre | : Physics |
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Download Physics Briefs Book in PDF, ePub and Kindle
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Total Pages | : 1290 |
Release | : 1983 |
Genre | : Nuclear energy |
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Download INIS Atomindex Book in PDF, ePub and Kindle
Author | : Derrick Kong |
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Total Pages | : 280 |
Release | : 2000 |
Genre | : Annihilation reactions |
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Download Measurement of the Total Cross Section for Hadronic Production by Ee− Annihilation at Energies Between 2-5 GeV Book in PDF, ePub and Kindle