Fri·Jun 12, 2020Friday·June 12, 2020

1. 01*

   The modified astrophysical S-factor of the ${}^{12}$C+${}^{12}$C fusion reaction at sub-barrier energies

   Y. J. Li🇨🇳 · X. Fang🇨🇳 · B. Bucher🇺🇸 · K. A. Li🇨🇳 · L. H. Ru · X. D. Tang🇨🇳

   The ${}^{12}$C+${}^{12}$C fusion reaction plays a crucial role in stellar evolution and explosions. Its open reaction channels mainly include $\alpha$, $p$, $n$, and ${}^8$Be. Despite more than a half century of efforts, large discrepancies remain among the experimental data measured using various techniques. In this work, we analyze the existing data using the statistical model. Our calculation shows: 1) the relative systematic uncertainties of the predicted branching ratios get smaller as the predicted ratios increase; 2) the total modified astrophysical S-factors (S${}^{\ast }$ factors) of the $p$ and $\alpha$ channels can each be obtained by summing the S${}^{\ast }$ factors of their corresponding ground-state transitions and the characteristic $\gamma$ rays while taking into account the contributions of the missing channels to the latter. After applying corrections based on branching ratios predicted by the statistical model, an agreement is achieved among the different data sets at $E_{cm}>$4 MeV, while some discrepancies remain at lower energies suggesting the need for better measurements in the near future. We find that the recent S${}^{\ast }$ factor obtained from an indirect measurement is inconsistent with the direct measurement at energies below 2.6 MeV. We recommend upper and lower limits for the ${}^{12}$C+${}^{12}$C S${}^{\ast }$ factor based on the existing models. A new ${}^{12}$C+${}^{12}$C reaction rate is also recommended.

   nucl-exastro-ph.SRnucl-thCPC(2020)·15 citations
2. 02*

   Turning up and down strong magnetic fields in relativistic nuclear collisions

   Giuliano Giacalone🇫🇷

   I show that the average transverse momentum, $⟨p_t⟩$, of the hadrons emitted in relativistic nuclear collisions can be used as a ``knob'' to control the strength of the magnetic field induced by the spectator and the participant protons over the overlap region. I thus argue that any observable sensitive to this magnetic field is nontrivially correlated with $⟨p_t⟩$ at a given collision centrality.

   ↳ nucl-thhep-exhep-phnucl-exPLB(2020)·2 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.