SystematicR-matrix analysis of theC13(p,γ)N

Abstract

Background: The proton capture reaction 13 C(p,γ) 14 N is an important reaction in the CNO cycle during the hydrogen burning in stars with mass greater than the mass of the Sun. It also occurs in the astrophysical sites like the red giant stars, the Asymptotic Giant Branch (AGB) stars. The low energy astrophysical S-factor of this reaction is dominated by a resonance state at an excitation energy of around 8.06 MeV (J π = 1 − ,T = 1) in 14 N. The other significant contributions come from the low energy tail of the broad resonance with J π = 0 − ,T = 1 at an excitation of 8.78 MeV and the direct capture process. Purpose: Measurements of low energy astrophysical S factor of the radiative capture reaction 13 C (p,γ) 14 N reported the extrapolated values of S(0) that differ by about 30%. Subsequent Rmatrix analysis and potential model calulations also yielded significantly different values for S(0). The present work intends to look into the dicrepancy through a detailed R-matrix analysis with emphasis on the associated uncertainties. Method A systematic reanalysis of the available decay data following the capture to the J π = 1 − , T = 1 resonance state of 14 N around 8.06 MeV excitation had been performed within the framework of R-matrix method. A simultaneous analysis of the 13 C(p,p0) data, measured over similar energy range, was carried out with the capture data. The data for the ground state decay of the broad resonance state (J π = 0 − , T = 1) around 8.78 MeV excitations was included as well. The external capture model along with the background poles to simulate the internal capture contribution were used to estimate the direct capture contribution. The asymptotic normalization constants (ANCs) for all states were extracted from the capture data. The multi-channel, multi-level R-matrix code AZURE2 was used for the calculation.Results The values of the astrophysical S-factor at zero relative energy, resulted from the present analysis are found to be consistent within the error bars for the two sets of capture data used. However, it is found from the fits to the elastic scattering data that the position of the J π = 1 − , T = 1 resonance state is uncertain by about 0.6 keV, prefering an excitation energy value of 8.062 MeV. Also the extracted ANC values for the states of 14 N corroborate with the values from the transfer reaction studies. The reaction rates from the present calculation are about 15-10 % lower than the values of NACRE II compilation but compares well with that from NACRE I. Conclusion The precise energy of the J π = 1 − , T = 1 resonance level around 8.06 MeV in 14 N must be determined. Further measurements around and below 100 keV with precision is necessary to reduce the uncertainty in the S-factor value at zero relative energy.

Gravitational lensing by rotating wormholes

“…By integrating the Gaussian curvature of the optical metric outwards from the light ray, we reveal that how the global topology plays an important role on the gravitational lensing in the wormhole spacetime. Studying weak gravitational lensing might potentially test the nature of rotating wormhole by comparing with black holes systems [35][36][37][38].…”

$B_s\to D^{(*)}_s l\nu$ form factors using heavy HISQ quarks

“…Light, strange and charm quarks are included in the sea, their masses are given in columns 4-6, and the valence quark masses in columns 7-9. These are tuned in [17]. We use a number of heavy quark masses to assist the extrapolation to physical b mass.…”

Update on ɛK with lattice QCD inputs

“…(1) are the same as in Ref. [1] except for the charm quark mass m c (m c ) = 1.2733(76) GeV, which is taken from the HPQCD collaboraion result [5]. They are given in Tables 1 and 2 The CKMfitter and UTfit collaboration provide the Wolfenstein parameters (λ,ρ,η, A) determined by the global unitarity triangle (UT) fit.…”