Small effects in astrophysical fusion reactions

Abstract

We study the combined effects of vacuum polarization, relativity, Bremsstrahlung, and atomic polarization in nuclear reactions of astrophysical interest. It is shown that these effects do not solve the longstanding differences between the experimental data of astrophysical nuclear reactions at very low energies and the theoretical calculations which aim to include electron screening.

Theory of the Coulomb Dissociation

“…[67], for important GT transitions whose strength are a small fraction of the sum rule the direct relationship between σ (p, n) and B(GT ) values also fails to exist. Similar discrepancies have been observed [68] for reactions on some odd-A nuclei including 13 C, 15 N, 35 Cl, and 39 K and for charge-exchange induced by heavy ions [66,69]. Undoubtedly, charge-exchange reactions such as (p,n), ( 3 He,t) and heavy-ion reactions (A,A±1) can provide information on the B(F) and B(GT ) values needed for astrophysical purposes [70].…”

“…Dynamical calculations have been performed, but they obviously cannot explain the discrepancy as they include atomic excitations and ionizations which reduce the energy available for fusion. Other small effects, like vacuum polarization, atomic and nuclear polarizabilities, relativistic effects, etc., have also been considered [13]. But the discrepancy between experiment and theory remains [13,10].…”

“…Other small effects, like vacuum polarization, atomic and nuclear polarizabilities, relativistic effects, etc., have also been considered [13]. But the discrepancy between experiment and theory remains [13,10].…”

Non-Inertial Effects in Reactions of Astrophysical Interest

“…For instance, the triple-alpha reaction which bridges the mass = 8 gap and forms carbon nuclei in stars relies on the lifetime of only 10 −17 s of 8 Be nuclei. It is during this time that another alpha-particle meets 8 Be nuclei in stars leading to the formation of carbon nuclei. This lifetime corresponds to an energy width of only 5.57 ± 0.25 eV [6].…”

“…As the third alpha particle approaches 8 Be, the effects of linear acceleration will be felt in the reference frame of 8 Be. This will likely broaden the width of the 8 Be resonance (which peaks at E R = 91.84 ± 0.04 KeV) and consequently its lifetime. However, this line of thought could be wrong if one assumes that the third alpha particle interacts individually with each of the two alpha particles inside 8 Be, and that the effects of acceleration internal to the 8 Be nucleus arise from the different distances (and thus accelerations) between the third alpha and each of the first two.…”