scholarly journals A Note on Resonance Angular Distributions with Application to Nucleon?Antinucleon Scattering and Annihilation

1973 ◽  
Vol 26 (4) ◽  
pp. 441
Author(s):  
DC Peaslee ◽  
DM Rosalky
Keyword(s):  
Angular Distributions ◽  
Unnatural Parity ◽  
Angular Momenta ◽  
Pseudoscalar Mesons ◽  
Natural Parity ◽  
Resonance Spin

Angular distributions have been calculated for the reactions NN -+ NN and NN -+ 2 pseudoscalar mesons by assuming the formation of an intermediate isolated state. The scattering distributions are only found to have the characteristic oscillatory shape for unnatural parity resonances whereas those for natural parity states are smooth. The annihilation distributions display an exact degeneracy with respect to the interchange of orbital and total angular momenta. For both reactions, the width of the forward and backward peak is approximately inversely proportional to the resonance spin.

The (K−,π−) and (π+, K+) Reactions and Λ-Hypernuclear Polarization

1994 ◽  
Vol 117 ◽  
pp. 17-53 ◽  
Author(s):  
K. Itonaga ◽  
T. Motoba ◽  
M. Sotona
Keyword(s):  
Experimental Data ◽  
Excited States ◽  
Cross Sections ◽  
Ground State ◽  
Weak Decay ◽  
Angular Distributions ◽  
Theoretical Studies ◽  
Excitation Functions ◽  
Unnatural Parity ◽  
Natural Parity

The theoretical studies of (K−, π−) and (π+, K+) reactions on p-shell targets are presented in the DWIA framework with use of the elementary spin-nonflip and spin-flip amplitudes. Calculations can explain the available experimental data of excitation functions and angular distributions of the (K−, π−) reactions at pK−=800 MeV/c and the (π+, K+) reactions at pπ+ = 1.04 GeV/c. Characteristic and distinguished features of the excitation functions and cross sections are exhibited. Especially it is demonstrated that the (K−, π−) reactions at pK−=1.1 GeV/c and 1.5 GeV/c can excite the unnatural parity states with comparable strength to the natural parity ones. Further interesting is that the (π+, K+) and (K−, π−) reactions with ∼1 GeV/c incident beams can be shown to produce very large polarizations of the produced hypernuclear states. Taking the subsequent deexcitation processes of the excited states into account, we have evaluated the hypernuclear polarization and Λ-spin polarization of the ground state and/or the ground-doublet states at the hypernuclear weak-decay stage, which would play a role in the hypernuclear coincidence experiment.

scholarly journals Time-reversal asymmetries and angular distributions in Λb → ΛV

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Chao-Qiang Geng ◽  
Chia-Wei Liu
Keyword(s):  
Time Reversal ◽  
Branching Ratio ◽  
New Physics ◽  
Angular Distributions ◽  
Factorization Approach ◽  
Spin Correlations ◽  
Angular Momenta ◽  
Pseudoscalar Mesons ◽  
Helicity Amplitudes ◽  
Cp Asymmetries

Abstract We study the spin correlations to probe time-reversal (T) asymmetries in the decays of Λb→ ΛV (V = ϕ, ρ0, ω, K∗0). The eigenstates of the T-odd operators are obtained along with definite angular momenta. We obtain the T-odd spin correlations from the complex phases among the helicity amplitudes. We give the angular distributions of Λb→ Λ(→ pπ−)V (→ PP′) and show the corresponding spin correlations, where P(′) are the pseudoscalar mesons. Due to the helicity conservation of the s quark in Λ, we deduce that the polarization asymmetries of Λ are close to −1. Since the decay of Λb→ Λϕ in the standard model (SM) is dictated by the single weak phase from the product of CKM elements, $$ {V}_{tb}{V}_{ts}^{\ast } $$ V tb V ts ∗ , the true T and CP asymmetries are suppressed, providing a clean background to test the SM and search for new physics. In the factorization approach, as the helicity amplitudes in the SM share the same complex phase, T-violating effects are absent. Nonetheless, the experimental branching ratio of Br(Λb→ Λϕ) = (5.18 ± 1.29) × 10−6 suggests that the nonfactorizable effects or some new physics play an important role. By parametrizing the nonfactorizable contributions with the effective color number, we calculate the branching ratios and direct CP asymmetries. We also explore the possible T-violating effects from new physics.

A quasi-classical trajectory (QCT) study of the H + OF reaction stereodynamics

2010 ◽  
Vol 88 (9) ◽  
pp. 893-897 ◽  
Author(s):  
Dan Zhao ◽  
Tian Yu Zhang ◽  
Tian Shu Chu
Keyword(s):  
Cross Sections ◽  
Relative Velocity ◽  
Collision Energy ◽  
Potential Surface ◽  
Excited Electronic State ◽  
Three Dimensional ◽  
Chem Phys ◽  
Classical Trajectory ◽  
Angular Distributions ◽  
Angular Momenta

Based on the global three-dimensional adiabatic potential surface of the 13A′ excited electronic state (J. Chem. Phys. 2005, 123, 114310) of the OHF system, we investigated the H + OF → OH + F/HF + O reaction stereodynamics by using the quasi-classical trajectory (QCT) method. The four polarization-dependent differential cross sections (PDDCSs) and the three angular distributions P(θr), P([Formula: see text]), P(θr, [Formula: see text]) were calculated at a low collision energy of 0.48 eV for both product channels. The results indicated that the products are backward-scattering on the triplet state, and the product rotational angular momenta are aligned or oriented. Moreover, there is a remarkable difference between the polarization behaviors of the two product channels. Product orientation exhibited by the OH + F channel is found to be absent in the HF + O channel at this collision energy albeit the latter shows stronger alignment along the direction perpendicular to the reagent relative velocity k than OH + F.

Study of the 48Ti(α,p)51V and 50Ti(3He,d)51V Reactions

1971 ◽  
Vol 49 (8) ◽  
pp. 1053-1065 ◽  
Author(s):  
P. N. Maheshwari ◽  
U. C. Gupta ◽  
C. St-Pierre
Keyword(s):  
Optical Model ◽  
Energy Levels ◽  
Angular Distributions ◽  
Model Parameters ◽  
Model Calculations ◽  
Angular Momenta ◽  
Rotator Model ◽  
Spectroscopic Factors ◽  
New Energy ◽  
Bombarding Energy

The reactions 48Ti(α,p)51V at ten bombarding energies between 8.25 and 10.75 MeV and 50Ti(3He,d)51V at 10 MeV bombarding energy have been studied. Energy levels of 51V up to 4.85 and 6.17 MeV have been observed by (α,p) and (3He,d) reactions respectively. The (α,p) reaction yielded many new energy levels. The angular distributions for deuterons were measured at lab angles between 15° and 120°, and compared with predictions of DWBA calculations using the TSALLY code from which the transferred angular momenta and spectroscopic factors were deduced. These experimental results are examined from the viewpoint of shell model and strong coupling rotator model calculations. The effect of changing various optical model parameters is also discussed.

Spin–Parity Combinations in 22Ne

1971 ◽  
Vol 49 (5) ◽  
pp. 594-600 ◽  
Author(s):  
R. W. Ollerhead ◽  
G. F. R. Allen ◽  
A. M. Baxter ◽  
B. W. J. Gillespie ◽  
J. A. Kuehner
Keyword(s):  
Band Structure ◽  
Alpha Particles ◽  
Energy Spectra ◽  
Spin Parity ◽  
Unnatural Parity ◽  
Natural Parity

Detection of inelastically scattered alpha particles near 180° from the reaction 22Ne(α,α′)22Ne has been used to identify natural parity levels in 22Ne. Energy spectra were recorded for ten incident energies from 16.5–21.0 MeV in steps of 500 keV. Levels at 4.46, 5.52, and 5.92 MeV have been identified as having natural parity, leading to definite assignments of 2+, 4+, and 2+ respectively. Levels at 5.14 and 5.64 MeV have been identified as having unnatural parity, implying assignments of 2− and 3+ respectively. Tentative assignments are suggested for other levels, and the implications of the present assignments with regard to the identification of band structure in 22Ne are discussed.

Angular distributions from ( d, p ) and ( d, n ) nuclear reactions

1951 ◽  
Vol 208 (1095) ◽  
pp. 559-579 ◽  
Keyword(s):  
Excited States ◽  
Ground State ◽  
Nuclear Reactions ◽  
Energy Levels ◽  
Angular Distributions ◽  
Angular Momenta ◽  
First Excited State ◽  
Compound Nucleus Formation ◽  
Initial Nucleus

Experimental angular distributions from (d, p) and (d, n) nuclear reactions involve con­tributions from incident angular momenta much higher than is compatible with compound nucleus formation, and indicate that these reactions must proceed to a large extent by means of a stripping process. The angular distributions to be expected from a stripping process are calculated, and these are found to be very sensitive to the angular momenta which can be accepted by the initial nucleus, i.e. to the spins and parities of the energy levels involved. In any one case there is found excellent agreement between the experimental curve and just one of the possible theoretical curves, and if the spin and parity of the ground state of the initial nucleus is known, this allows of a determination of the spin and parity of the appropriate level of the final nucleus. In this way it is found, for example, that the ground state of 17 O has spin ⅝ or ⅜ and even parity, and that the first excited state of 17 O (0.88 MeV above ground) has spin ½ and even parity. Determinations are also made of the spins and parities of the ground states and several excited states of 13 C, 15 N and 28 Al. Families of theoretical curves for a variety of incident and outgoing energies are presented in order to facilitate further spin and parity determinations from future experimental results.

scholarly journals Elastic scattering of slow electrons by carbon nanotubes

2021 ◽  
Author(s):  
Miron Ya. Amusia ◽  
Arkadiy S Baltenkov
Keyword(s):  
Carbon Nanotubes ◽  
Elastic Scattering ◽  
Cross Sections ◽  
Angular Distributions ◽  
Slow Electron ◽  
Scattering Cross ◽  
Angular Momenta ◽  
Incoming Electron ◽  
Slow Electrons ◽  
Scattering Cross Sections

Abstract In this paper we calculate the elastic scattering cross sections of slow electron by carbon nanotubes. The corresponding electron-nanotube interaction is substituted by a zero-thickness cylindrical potential that neglects the atomic structure of real nanotubes, thus limiting the range of applicability of our approach to sufficiently low incoming electron energies. The strength of the potential is chosen the same that was used in describing scattering of electrons by fullerene C60. We present results for total and partial electron scattering cross sections as well as respective angular distributions, all with account of five lowest angular momenta contributions. In the calculations we assumed that the incoming electron moves perpendicular to the nanotube axis, since along the axis the incoming electron moves freely.

Spin–Parity Combinations in 18O

1971 ◽  
Vol 49 (20) ◽  
pp. 2589-2598 ◽  
Author(s):  
R. W. Ollerhead ◽  
G. F. R. Allen ◽  
A. M. Baxter ◽  
J. A. Kuehner
Keyword(s):  
Negative Parity ◽  
Alpha Particles ◽  
Energy Spectra ◽  
Excitation Energies ◽  
Spin Parity ◽  
Unnatural Parity ◽  
Parity Band ◽  
Natural Parity ◽  
Negative Parity Band

Detection of inelastically scattered alpha particles near 180° from the reaction 18O(α,α′)18O has been used to identify natural parity levels in 18O. Energy spectra were recorded for 13 incident energies from 20.0 to 23.4 MeV. Levels at 4.45, 5.09, and 5.25 MeV have been identified as having natural parity, confirming earlier assignments of 1−, 3−, and 2+, respectively. Levels at 5.37 and 5.52 MeV have been identified as having unnatural parity leading to definite assignments of 3+ and 2−, respectively. The spin and parity of the 6.18 MeV level has been restricted to 1− or 2+. Other levels at higher excitation energies have been assigned natural parity, and the implications with regard to the identification of a negative parity band in 18O are discussed.

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