119329980
Compton Scattering on He-3
We present first calculations for Compton scattering on $^3$He. The objective of the calculation is an extraction of the neutron polarizabilities.
118407568
Chiral potentials, perturbation theory and the 1S0 channel of NN scattering
We use nucleon–nucleon phase shifts obtained from experimental data, together with the chiral expansion for the long-distance part of the NN interaction, to obtain information about the short-distance piece of the NN potential that is at work in the 1S0 channel. We find that if the scale R that defines the separation between 'long-' and 'short-' distance is chosen to be 1.8 fm then the energy dependence produced by short-distance dynamics is well approximated by a two-term polynomial for Tlab ≤ 200 MeV. We also find that a quantitative description of NN dynamics is possible, at least in this channel, if one treats the long-distance parts of the chiral NN potential in perturbation theory. However, in order to achieve this we have to choose a separation scale R that is larger than 1.0 fm.
9428112
Investigating neutron polarizabilities through Compton scattering on 3He.
We examine manifestations of neutron electromagnetic polarizabilities in coherent Compton scattering from the helium-3 nucleus. We calculate gamma3He elastic scattering observables using chiral perturbation theory to next-to-leading order [O(e2Q)]. We find that the unpolarized differential cross section can be used to measure neutron electric and magnetic polarizabilities, while two double-polarization observables are sensitive to different linear combinations of the four neutron spin polarizabilities.
53550289
Analyzing the effects of neutron polarizabilities in elastic Compton scattering off 3He
Abstract Motivated by the fact that a polarized 3He nucleus is expected to behave approximately as a polarized neutron, we examine manifestations of neutron electromagnetic polarizabilities in elastic Compton scattering from the Helium-3 nucleus. We calculate both unpolarized and double-polarization observables using chiral perturbation theory to next-to-leading order ( O ( e 2 Q ) ) at energies, ω ≲ m π , where m π is the pion mass. Our results show that the unpolarized differential cross-section can be used to measure neutron electric and magnetic polarizabilities, while two double-polarization observables are sensitive to different linear combinations of the four neutron spin polarizabilities.
119110936
Universal correlations in pion-less EFT with the resonating group method: Three and four nucleons
Abstract.The Effective Field Theory “without pions” at next-to-leading order is used to analyze universal bound-state and scattering properties of the 3- and 4-nucleon system. Results of a variety of phase shift equivalent nuclear potentials are presented for bound-state properties of 3H and 4He , and for the singlet S -wave 3He -neutron scattering length a0(3He-n) . The calculations are performed with the Refined Resonating Group Method and include a full treatment of the Coulomb interaction and the leading-order 3-nucleon interaction. The results compare favorably with data and values from AV18(+UIX) model calculations. A new correlation between a0(3He-n) and the 3H binding energy is found. Furthermore, we confirm at next-to-leading order the correlations, already found at leading order, between the 3H binding energy and the 3H charge radius, and the Tjon line. With the 3H binding energy as input, we get predictions of the effective field theory “without pions” at next-to-leading order for the root mean square charge radius of 3H of (1.6±0.2) fm, for the 4He binding energy of (28±2.5) MeV, and for Re{a0(3He-n)} of (7.5±0.6) fm. Including the Coulomb interaction, the splitting in binding energy between 3H and 3He is found to be (0.66±0.03) MeV. The discrepancy to data of (0.10±0.03) MeV is model independently attributed to higher-order charge independence breaking interactions. We also demonstrate that different results for the same observable stem from higher-order effects, and carefully assess that numerical uncertainties are negligible. Our results demonstrate the convergence and usefulness of the pion-less theory at next-to-leading order in the 4He channel. We conclude that no 4-nucleon interaction is needed to renormalize the theory at next-to-leading order in the 4-nucleon sector.
55918790
Compton Scattering on Light Nuclei
Compton scattering on light nuclei (A = 2, 3) has emerged as an effective avenue to search for signatures of neutron polarizabilities, both spin-independent and spin-dependent ones. In this discussion I will focus on the theoretical aspect of Compton scattering on light nuclei; giving first a brief overview and therafter concentrating on our Compton scattering calculations based on Chiral effective theory at energies of the order of pion mass. These elasticγd andγHe-3 calculations include nucleons, pions as the basic degrees of freedom. I will also discuss γd results where the� -isobar has been included explicitly. Our results on unpolarized and polarization observables suggest that a combination of experiments and further theoretical efforts will provide an extraction of the neutron polarizabilities.
119264904
The Oscillation Frequency of B and bar B Mesons in a QCD Potential Model with Relativistic Effects
Wavefunction at the origin, with the incorporation of a relativistic effect, leads to singularity in a specific potential model. To regularize the wavefunction, we introduced a short distance scale and used it to estimate the mass and decay constants of Bd and Bs mesons within the QCD potential model. These values were then used to compute the oscillation frequency, ΔmB, of Bd and Bs mesons. The values were found to be in good agreement with experimental and other theoretical values.
121696463
Form factors and charge radii in a quantum chromodynamics-inspired potential model using variationally improved perturbation theory
We use variationally improved perturbation theory (VIPT) for calculating the elastic form factors and charge radii of D,Ds,B,Bs and Bc mesons in a quantum chromodynamics (QCD)-inspired potential model. For that, we use linear-cum-Coulombic potential and opt the Coulombic part first as parent and then the linear part as parent. The results show that charge radii and form factors are quite small for the Coulombic parent compared to the linear parent. Also, the analysis leads to a lower as well as upper bounds on the four-momentum transfer Q2, hinting at a workable range of Q2 within this approach, which may be useful in future experimental analyses. Comparison of both the options shows that the linear parent is the better option.