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 elastic $\gamma$d and $\gamma$He-3 calculations include nucleons, pions as the basic degrees of freedom. I will also discuss $\gamma$d results where the $\Delta$-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.Comment: 10 pages, 14 figures. Contribution to the proceedings of the IUPAP Conference on Few-Body Problems in Physics, Aug 31 - Sep 5, 2009, Bonn, German

Nonperturbative renormalization of the neutrinoless double-beta operator in p-shell nuclei

We use Lee-Suzuki mappings and related techniques to construct effective two-body p-shell interactions and neutrinoless double-beta operators that exactly reproduce the results of large no-core-shell-model calculations of double-beta decay in nuclei with mass number A=6. We then apply the effective operators to the decay of nuclei with A=7, 8, and 10, again comparing with no-core calculations in much larger spaces. The results with the effective two-body operators are generally good. In some cases, however, they differ non-negligibly from the full no-core results, suggesting that three-body corrections to the decay operator in heavier nuclei may be important. An application of our procedure and related ideas to fp-shell nuclei such as 76Ge should be feasible within coupled-cluster theory.Comment: 6 pages, 4 figure

Compton scattering from the proton: An analysis using the delta expansion up to N3LO

We report on a chiral effective field theory calculation of Compton scattering from the proton. Our calculation includes pions, nucleons, and the Delta(1232) as explicit degrees of freedom. It uses the "delta expansion", and so implements the hierarchy of scales m_pi < M_Delta-M_N < Lambda_chi. In this expansion the power counting in the vicinity of the Delta peak changes, and resummation of the loop graphs associated with the Delta width is indicated. We have computed the nucleon Compton amplitude in the delta expansion up to N3LO for photon energies of the order of m_pi. This is the first order at which the proton Compton scattering amplitudes receive contributions from contact operators which encode contributions to the spin-independent polarisabilities from states with energies of the order of Lambda_chi. We fit the coefficients of these two operators to the experimental proton Compton data that has been taken in the relevant photon-energy domain, and are in a position to extract new results for the proton polarisabilities alpha and beta.Comment: 6 pages. Proceeding of Sixth International Workshop on Chiral Dynamics, Bern (Switzerland), 6th -- 10th July 2009. To be published in Po

Elastic Compton Scattering from 3He and the Role of the Delta

We report observables for elastic Compton scattering from $^3$He in Chiral Effective Field Theory with an explicit $\Delta(1232)$ degree of freedom ($\chi$EFT) for energies between 50 and 120 MeV. The $\gamma\,{}^3$He amplitude is complete at N3LO, $\mathcal{O}(e^2\delta^3)$, and in general converges well order by order. It includes the dominant pion-loop and two-body currents, as well as the Delta excitation in the single-nucleon amplitude. Since the cross section is two to three times that for deuterium and the spin of polarised $^3$He is predominantly carried by its constituent neutron, elastic Compton scattering promises information on both the scalar and spin polarisabilities of the neutron. We study in detail the sensitivities of 4 observables to the neutron polarisabilities: the cross section, the beam asymmetry and two double asymmetries resulting from circularly polarised photons and a longitudinally or transversely polarised target. Including the Delta enhances those asymmetries from which neutron spin polarisabilities could be extracted. We also correct previous, erroneous results at N2LO, i.e.~without an explicit Delta, and compare to the same observables on proton, neutron and deuterium targets. An interactive Mathematica notebook of our results is available from [email protected]: 37 pages LaTeX2e (pdflatex) including 16 figures as .pdf files using includegraphics; minor corrections, triggered by referee comments, plus typographical errors; text-identical to version published as EPJA 54 (2018) 12

SUSTAINED RELEASE TABLETS OF SORAFENIB-SILIBININ COMBINATIONS FOR THE TREATMENT OF HEPATOCELLULAR CARCINOMA

Objective: The aim of this study was to develop polymer coated sustained release tablet using sorafenib and silibinin combination for the treatment of hepatocellular carcinoma. Methods: The qualitative analysis such as weight variation, friability, hardness, interaction studies, disintegration and in vitro release were performed to validate formulated tablets. We have maintained the acceptable official limits for weight variation, friability, hardness and disintegration time according to prescribed pharmacopoeial recommendation. In vitro drug release studies were performed using USP-II (paddle type) dissolution apparatus. The MTT assay was performed for assessment of Cell viability of drug combination for tablet formulation. Molecular docking studies have been performed to determine the combinatorial mode of action for the tablet formulation. Results: Friability and weight variation were less than 1% for each formulation, which were within range of prescribed pharmacopoeial recommendation. The hardness of 20 tablets showed 5-6.5Kg/cm2 for all formulations 5-6.5Kg/cm2. The optimized formulation resulted in 98% drug release after 28 h. The present study reports the synergistic effects of drug combination to inhibit cell growth in HepG2 cell line. Molecular docking studies showed that sorafenib has high binding affinity for B-Raf vascular endothelial growth factor receptor β and protein kinase B. Silibinin showed binding affinity with MAP kinase-11, protein phosphatase 2 A and tankyrase. Conclusion: The present study reports for the first time a novel formulation for sustained release and reduced toxicity of sorafenib with enhanced inhibitory effect of the drug combination on cancerous hepatic cell line as well collaborative mechanism of action for the formulation

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 \lsim 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.Comment: 19 pages, 4 figure

Analyzing the Effects of Neutron Polarizabilities in Elastic Compton Scattering off 3{}^3He

Motivated by the fact that a polarized ${}^3$He nucleus behaves as an `effective' neutron target, 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 (${\mathcal O}(e^2 Q)$) at energies, $\omega \leq m_{\pi}$, where $m_{\pi}$ 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. [Note added in 2018] The qualitative conclusions and analytic formulae presented in this paper are correct, but several of the numerical results are wrong: see the erratum posted as arXiv:1804.01206 for further details. A full suite of corrected numerical results for cross sections and asymmetries can be found in Margaryan et al., arXiv:1804.00956. They can also be obtained as an interactive Mathematica notebook by emailing [email protected]: 40 pages, 16 figure