Related papers: $S$-factor and scattering parameters from ${}^3$He…
Previous studies of the reaction ${}^{3}\mathrm{He} +{}^{4}\mathrm{He} \rightarrow {}^{7}\mathrm{Be} + \gamma$ have focused on providing the best central value and error bar for the $S$ factor at solar energies. Measurements of this capture…
We treat low-energy $^3$He-$\alpha$ elastic scattering in an Effective Field Theory (EFT) that exploits the separation of scales in this reaction. We compute the amplitude up to Next-to-Next-to-Leading Order (NNLO), developing a hierarchy…
Differential cross sections for $^3$He-$\alpha$ scattering were measured in the energy range up to 3 MeV. These data together with other available experimental results for $^3$He $+ \alpha$ and $^3$H $+ \alpha$ scattering were analyzed in…
We calculate the cross section for radiative capture $^3$He$(\alpha,\gamma)^7$Be at next-to-next-to-leading order (NNLO). At this order of perturbation, momentum dependent two-body currents make their first appearance. We provide a…
We report an improved low-energy extrapolation of the cross section for the process Beryllium-7+proton -> Boron-8+photon, which determines the Boron-8 neutrino flux from the Sun. Our extrapolant is derived from Halo Effective Field Theory…
The $^3$He$(\alpha,\gamma)^7$Be radiative capture reaction plays a key role in the creation of elements in stars as well as in the production of solar neutrinos, the observation of which is one of the main tools to study the properties of…
In this work we study the radiative capture of ${\rm {}^3He}$ on ${\rm {}^4He}$ within the halo effective field theory (EFT) framework. At leading order the capture amplitude comprises the initial state $s$-wave strong and Coulomb…
The astrophysical $^7{\rm Be}(p, \gamma)^8{\rm B}$ direct capture process is studied in the framework of a two-body single-channel model with potentials of the Gaussian form. A modified potential is constructed to reproduce the new…
We present a new accurate analysis of the $^3$He$(p,e^+\nu_e)$${}^4$He (''hep'') reaction at astrophysical energies. The S-factor is computed using a state-of-the-art method to calculate the four-nucleon scattering and bound-state wave…
The $S_{E1}$-factor of radiative $\alpha$-capture on $^{12}$C is studied in effective field theory up to next-to-leading order. A modification of the counting rules for the radiative capture amplitudes is discussed. We find that only two…
Recently we succeeded to make a reliable EFT prediction in a totally parameter-free manner for the $S$ factors for the solar $pp$ and $hep$ processes, $p+p\to d + e^+ +\nu_e$ and $\He3+p \to \He4 + e^+ + \nu_e$. The strategy used in there…
Study of radiative $\alpha$ capture on $^{12}$C, $^{12}$C($\alpha$,$\gamma$)$^{16}$O, in cluster effective field theory (EFT) is reviewed. A low energy EFT for $^{12}$C($\alpha$,$\gamma$)$^{16}$O at the Gamow-peak energy, $E_G=0.3$~MeV, is…
The radiative capture of protons by $^7$Be, which is the source of $^8$B that $\beta$-decays emitting the majority of solar neutrinos measured on earth, has not yet been measured at astrophysically relevant energies. The recommended value…
Spurred by the recent complete determination of the weak currents in two-nucleon systems up to ${\cal O}(Q^3)$ in heavy-baryon chiral perturbation theory, we carry out a parameter-free calculation of the threshold $S$-factors for the solar…
We investigate the energy dependence of the astrophysical $S$ factor for the reaction $^7$Be$(p,\gamma)^8$B, the primary source of high-energy solar neutrinos in the solar $pp$ chain. Using simple models we explore the model dependence in…
We report a leading-order (LO) calculation of $^7\mathrm{Be}(p,\gamma)^8\mathrm{B}$ in a low-energy effective field theory. $^8\mathrm{B}$ is treated as a shallow proton$+^7\mathrm{Be}$ core and proton$+^7\mathrm{Be}^{*}$ (core excitation)…
We employ an effective field theory (EFT) that exploits the separation of scales in the p-wave halo nucleus $^8\mathrm{B}$ to describe the process $^7\mathrm{Be}(p,\gamma)^8\mathrm{B}$ up to a center-of-mass energy of 500 keV. The…
A new analysis of the precise experimental astrophysical $S$-factors for the direct capture $^3He(\alpha,\gamma)^7{\rm {Be}}$ reaction [B.S. Nara Singh et al., Phys.Rev.Lett. {\bf 93} (2004) 262503; D. Bemmerer et al., Phys.Rev.Lett. {\bf…
Using effective field theory, we calculate the S-factor for the hep process in a totally parameter-free formulation. The transition operators are organized according to chiral counting, and their matrix elements are evaluated using the…
Astrophysical S-factors at zero energy for the direct nuclear capture reactions $^{3}{\rm He}(\alpha, \gamma)^{7}{\rm Be}$, $^{3}{\rm H}(\alpha, \gamma)^{7}{\rm Li}$ and $^{7}{\rm Be}(p, \gamma)^{8}{\rm B}$ are estimated within the…