Calculation of parity non-conserving pp-scattering amplitudes and analysis of a 45 MeV measurement

Calculations of parity non-conserving (PNC) amplitudes are presented and used to analyze a measurement of the longitudinal analyzing power A_z in 45 MeV p-p scattering. For the PNC interaction the usual parametrization in terms of one meson exchanges is used while the strong scattering states are obtained from the Paris potential and, for comparison, also from the Reid soft core potential. The dependence on weak and strong parameters is exhibited.     

Calculation of forward proton-proton bremsstrahlung at 51.8 MeV

The double differential proton-proton bremsstrahlung cross section near 10^O−10^O is computed in the coplaner geometry using a simple one pion exchange off-shell extrapolation of the elastic phase shifts. This relatively simple calculation which has given excellent agreement with experiments at θ₁, θ₂ > 25^O does not agree with recent Japanese 8.5^O-8.5^O data at 51.8 MeV.     

Reconciliation of the measurement of parity nonconservation in Cs with the standard model

Contributions from the Breit interaction in atomic structure calculations account for 1.3sigma of the previously reported 2. 5sigma deviation from the standard model in the 133Cs weak charge [S. C. Bennett and C. E. Wieman, Phys. Rev. Lett. 82, 2484 (1999)]. The updated corrections for the neutron distribution reduce the discrepancy further to 1.0sigma. The updated value of the weak charge is Q(W)(133Cs) = -72.65(28)(expt)(34)(theor).     

"Ridge" in proton-proton scattering at 7 TeV

One of the most important experimental results for proton-proton scattering at the LHC is the observation of a so-called "ridge" structure in the two-particle correlation function versus the pseudorapidity difference Δη and the azimuthal angle difference Δφ. One finds a strong correlation around Δφ=0, extended over many units in Δη. We show that a hydrodynamical expansion based on flux tube initial conditions leads in a natural way to the observed structure. To get this result, we have to perform an event-by-event calculation, because the effect is due to statistical fluctuations of the initial conditions, together with a subsequent collective expansion. This is a strong point in favor of a fluidlike behavior even in pp scattering, where we have to deal with length scales of the order of 0.1 fm.     

Parity nonconservation in pα scattering

The elastic scattering of longitudinally polarized protons on ⁴He at energy E_p ? 15 MeV is considered. The difference of cross sections for protons of positive and negative helicities which is due to the weak interaction is calculated. The magnitude of the effect reaches 2–3 × 10^?7.     

Precise measurement of dp elastic scattering at 270 MeV and three-nucleon force effects

The cross section, the deuteron vector A(d)(y) and tensor analyzing powers A(ij), the polarization transfer coefficients K(y('))(ij), and the induced polarization P(y(')) were measured for the dp elastic scattering at 270 MeV. The cross section and A(d)(y) are well reproduced by Faddeev calculations with modern data-equivalent nucleon-nucleon forces plus the Tucson-Melbourne three-nucleon force. In contrast, A(ij), K(y('))(ij), or P(y(')) are not described by such calculations. These facts indicate the deficiencies in the spin dependence of the Tucson-Melbourne force and call for extended three-nucleon force models.     

DWIA analysis of quasifree proton-proton scattering in nuclei at intermediate energies

The distorted wave impulse approximation to the (p, 2p) reaction cross section is briefly reviewed, having foremost in mind its practical implementation as a computer program, suitable for extracting information on nuclear structure. The treatment of the distorted waves, and the approximation of the overlap integral between the ground state of the target nucleus and the final state of the residual nucleus, are discussed in more detail. As far as possible we have chosen methods which enable us to minimize the number of free reaction-theoretical parameters by deducing them from independent experimental data. As an illustration of how one can use a program constructed according to these principles, we analyze 460 MeV and 600 MeV data on the reaction ⁴⁰Ca(p, 2p)³⁹K with rather detailed discussion of various theoretical and experimental questions that must be taken into consideration before any conclusions can be drawn.     

Polarization in neutron-proton scattering at 16.2 MeV

The polarization in the scattering of neutrons from protons has been measured at a lab neutron energy of 16.2 MeV for the three c.m. angles 70°, 100° and 130°, at which the measured polarizations were (+2.95 ± 0.86) %, (+1.84 ± 0.91)% and (+1.62 ± 0.99) % respectively.     

Polarisation in neutron-deutron scattering at 30 MeV

The polarisation asymmetry in elastic$\text{n}\text{?d}$ scattering has been measured at 30 MeV from 45° to 140° c.m. neutron angle with uncertainties less than 0.03.     

Proton-nucleus elastic scattering at 156 MeV

Cross sections for the elastic scattering of 156 MeV protons on eleven targets ranging from ¹²C to ²⁰⁹Bi were measured and an optical model analysis has been performed. The effect of different optical potentials in DWIA inelastic scattering calculations is shown by some examples.     

Resonant Bhabha scattering at MeV energies

We discuss, on a phenomenological level, the possible appearance of resonances ine ⁺+e ^? scattering at energies in the MeV region. The expected resonance cross section and angular distribution are examined. The observability depends crucially on the attainable energy resolution which is limit by the momentum distribution of the electrons contained in the target.     

Inelastic p-He scattering at 141 MeV

Inelastic p-⁴He scattering at 141±2 MeV has been investigated with a high-pressure cloud chamber filled with helium. Results are presented for the total cross sections of each reaction channel and the neutron spectra for the p(⁴He, pn)³He reaction.     

Neutron-proton elastic scattering at 325 MeV

Accurate measurements of the P and D_T parameters in np elastic scattering at 325 MeV resolve a major ambiguity in the phase shift analysis. The mixing parameters $\text{ε}{}_1\text{= 8.4 ± 0.6°}$ and $\text{ε}{}_3\text{= 7.2 ± 0.4°}$ are particularly well determined, and in good agreement with theoretical expectations.