120279074
Some results in the effective theory of heavy quarks
Abstract An effective theory of QCD systems containing heavy quarks is introduced. Heavy meson and heavy baryon matrix elements relevant for the semileptonic weak decays are discussed. Applications to the e + e − production of heavy mesons and baryons are presented.
125011745
Heavy quark effective theory
After a brief introduction, the results of application of the heavy quark effective theory to semileptonic decays of beta mesons are discussed. A nearly-model-independent extraction of {vert_bar}V{sub cb}{vert_bar} from data is described. Application of the effective theory to inclusive semileptonic decays of heavy mesons, in semileptonic decays of heavy baryons, and to the nonleptonic decays of hadrons are outlined. The authors conclude by mentioning other areas of research in this very active field.
117025439
On the Monopole Model of Form Factors for Heavy Meson Decays
A pole model for the form factors describing heavy to light meson transitions is constructed, and the results compared with the predictions of the heavy quark effective theory (HQET). While most of the HQET-predicted relationships among form factors hold at the maximum value of q{sup 2}, many are violated, suggesting that the simplest version of the pole model of meson form factors should be used with caution, especially when combined with HQET.
123512923
Sequential fragmentation and rate oscillations in exclusive decays
Abstract We consider the decay of heavy quarkonia into two light mesons, and assume that quark-antiquark pairs are created sequentially when the final state is formed. We find quantum oscillations in the decay rate as a function of total energy. These oscillations can explain the energy dependence observed in the πϱ and K ∗ K channels at the J ψ and ψ ′ and predict the behaviour at the heavier Ψ family. In the mechanism we discuss, a given final state is produced only in a narrow range of the possible distances between the initial light quark and light antiquark.
120605148
Partial-wave analysis of lepton-pair annihilation into two photons
The partial-wave (Jp) composition of the process l+l− → γγ is analyzed in lowest order quantum electrodynamics. The results for low-momentum leptons are as expected, the partial wave with Jp = 0− being dominant. At high energies, the partial wave with Jp = 2+ has the largest single partial cross section. At all energies, it is found that lepton pairs in the triplet state give rise exclusively to positive-parity final states, whereas pairs in the singlet state give rise to negative-parity final states.Some features of the differential cross section are also explained in terms of the spin state of the annihilating lepton pair. Possible implications for e+e− → γγ → hadrons and hadrons are briefly discussed.
119191937
Photoproduction of meson pairs: First measurement of the polarization observable I**s
Abstract The polarization observable I s , a feature exclusive to the acoplanar kinematics of multi-meson final states produced via linearly polarized photons, has been measured for the first time. Results for the reaction γ → p → p π 0 η are presented for incoming photon energies between 970 MeV and 1650 MeV along with the beam asymmetry I c . The comparably large asymmetries demonstrate a high sensitivity of I s to the dynamics of the reaction. The sensitivity of these new polarization observables to the contributing partial waves is demonstrated by fits using the Bonn–Gatchina partial wave analysis.
120869047
Elastic Scattering of 580-MeV Protons from He 3
The elastic differential cross section for $p$-$^{3}\mathrm{He}$ scattering has been measured at 580 MeV. The data are compared with a Glauber model calculation.
123621996
Large-angle p-d scattering at 580 Mev
121222499
Elastic pd Scattering at 316, 364, 470, and 590 MeV in the Backward Hemisphere
The results of an investigation of the elastic $\mathrm{pd}$ differential cross section for center-of-mass angles between 91 and 164\ifmmode^\circ\else\textdegree\fi{} at energies of 316, 364, 470, and 590 MeV are presented. For center-of-mass scattering angles larger than 130\ifmmode^\circ\else\textdegree\fi{}, the cross sections at any given angle are within 10% of each other for the three largest energies. The extrapolated 180\ifmmode^\circ\else\textdegree\fi{} differential cross section observed in this experiment remains nearly constant from 316 to 590 MeV. This is in marked contrast to the rapid decrease in cross section with increasing energy observed by other investigators for both larger and smaller energies. Possible theoretical explanations of this behavior are mentioned.
93503786
Quasi-Elastic Reactions with 600 MeV Protons
A measurement of the (p,2p) differential cross section dσ/dEdΩldΩ2 at 600 MeV on Deuterium and Helium-4 at the NASA Space Radiation Effects Laboratory is reported [1], [2]. Two coincident protons were detected with identical range telescopes. The energy sum of the outgoing protons was constrained to be equal to the incident energy minus the S-state proton separation energy, 2.2 and 20.4 MeV for D and He-4, respectively. By varying the detection angles symmetrically to the beam, events were selected with nuclear recoil momentum \(\vec q_r = \vec p_o - (\vec p_1 + \vec p_2 )\) along the beam line. Values of qr up to 370 MeV/c in D and 300 MeV/c in He-4 were observed.
120709149
Elastic scattering of 600-MeV protons from H, D, He-3, and He-4.