117217556
Hen Process in Effective Field Theory
An effective field theory technique that combines the standard nuclear physics approach and chiral perturbation theory is applied to the $hen$ process, ${}^{3}{He}+n\to {}^{4}{He}+ \gamma$. For the initial and final nuclear states, high-precision wave functions are generated via the variational Monte Carlo method using the Argonne $v_{14}$ potential and Urbana VIII trinucleon interactions, while the relevant transition operators are calculated up to ${\cal O}(Q^4)$ in HB$\chi$PT. The imposition of the renormalization condition that the magnetic moments of ${}^{3}{He}$ and ${}^{3}{H}$ be reproduced allows us to carry out a parameter-free calculation of the $hen$ cross section. The result, $\sigma=(60\pm 3\pm 1) \mu b$, is in reasonable agreement with the experimental values, $(54\pm 6) \mu b$ and $(55\pm 3) \mu b$. This agreement demonstrates the validity of the calculational method previously used for estimating the reaction rate of the solar $hep$ process.
30412984
Faddeev-type equations for three-body symmetry violating scattering amplitudes
The equations which relate three-body and two-body symmetry violating scattering amplitudes are derived in the first order of symmetry violating interactions. They can be used to obtain three-body symmetry violating scattering amplitudes from two-body symmetry violating scattering amplitudes calculated in low energy effective field theory.
118603804
Up to N{sup 3}LO heavy-baryon chiral perturbation theory calculation for the M1 properties of three-nucleon systems
M1 properties, comprising magnetic moments and radiative capture of thermal neutron observables, are studied in two- and three-nucleon systems. We use meson exchange current derived up to N{sup 3}LO using heavy baryon chiral perturbation theory a la Weinberg. Calculations have been performed for several qualitatively different realistic nuclear Hamiltonians, which permits us to analyze model dependence of our results. Our results are found to be strongly correlated with the effective range parameters such as binding energies and the scattering lengths. Taking into account such correlations, the results are in good agreement with the experimental data with small model dependence.
7547091
Effective field theory approach for the M1 properties of A=2 and 3 nuclei
Abstract The magnetic moments of 2 H, 3 He and 3 H as well as the thermal neutron capture rate on the proton are calculated using heavy baryon chiral perturbation theory a la Weinberg. The M1 operators have been derived up to N 3 LO. The nuclear matrix elements are evaluated with the use of wave functions obtained by carrying out variational Monte Carlo calculations for a realistic nuclear Hamiltonian involving high-precision phenomenological potentials like Argonne Av18 and Urbana IX tri-nucleon interactions. We discuss the potential- and cutoff-dependence of the results.
36350052
Time reversal invariance violation in neutron-deuteron scattering
Time reversal invariance-violating (TRIV) effects in low-energy elastic neutron-deuteron scattering are calculated using meson exchange and EFT-type TRIV potentials in a distorted-wave Born approximation with realistic hadronic strong interaction wave functions, obtained by solving the three-body Faddeev equations in configuration space. The relation between TRIV and parity-violating observables is discussed.
122612188
Heavy-baryon chiral perturbation theory approach to thermal neutron capture on He 3
The cross section for radiative thermal neutron capture on {sup 3}He ({sup 3}He+n{yields}{sup 4}He+{gamma}; known as the hen reaction) is calculated based on heavy-baryon chiral perturbation theory. The relevant M1 operators are derived up to next-to-next-to-next-to-leading order (N{sup 3}LO). The initial and final nuclear wave functions are obtained from the rigorous Faddeev-Yakubovski equations for five sets of realistic nuclear interactions. Up to N{sup 3}LO, the M1 operators contain two low-energy constants, which appear as the coefficients of nonderivative two-nucleon contact terms. After determining these two constants using the experimental values of the magnetic moments of the triton and {sup 3}He, we carry out a parameter-free calculation of the hen cross section. The results are in good agreement with the data.
15149403
Notes from the Underground: A Propos of Givental's Conjecture
These brief notes record our puzzles and findings surrounding Givental's recent conjecture which expresses higher genus Gromov-Witten invariants in terms of the genus-0 data. We limit our considerations to the case of a projective line, whose Gromov-Witten invariants are well-known and easy to compute. We make some simple checks supporting his conjecture.
119216515
Shear and bulk viscosities of a weakly coupled quark gluon plasma with finite chemical potential and temperature: Leading-log results
We calculate the shear (eta) and bulk (zeta) viscosities of a weakly coupled quark gluon plasma at the leading-log order with finite temperature T and quark chemical potential mu. We find that the shear viscosity to entropy density ratio eta/s increases monotonically with mu and eventually scales as (mu/T)^2 at large mu. In contrary, zeta/s is insensitive to mu. Both eta/s and zeta/s are monotonically decreasing functions of the quark flavor number N_f when N_f \geq 2. This property is also observed in pion gas systems. Our perturbative calculation suggests that QCD becomes the most perfect (i.e. with the smallest eta/s) at mu=0 and N_f = 16 (the maximum N_f with asymptotic freedom). It would be interesting to test whether the currently smallest eta/s computed close to the phase transition with mu=0 and N_f = 0 can be further reduced by increasing N_f.