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Register a new userMonte-Carlo Study of Bound States in a Few-Nucleon System - Method of Continued Fractions -
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We propose a new type of Monte-Carlo method which enables us to study the excited state of many-body systems.
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Experimental form factors of the hydrogen and helium isotopes, extracted from an up-to-date global analysis of cross sections and polarization observables measured in elastic electron scattering from these systems, are compared to predictions obtained in three different theoretical approaches: the first is based on realistic interactions and currents, including relativistic corrections (labeled as the conventional approach); the second relies on a chiral effective field theory description of the strong and electromagnetic interactions in nuclei (labeled $chi$EFT); the third utilizes a fully relativistic treatment of nuclear dynamics as implemented in the covariant spectator theory (labeled CST). For momentum transfers below $Q lesssim 5$ fm$^{-1}$ there is satisfactory agreement between experimental data and theoretical results in all three approaches. However, at $Q gtrsim 5$ fm$^{-1}$, particularly in the case of the deuteron, a relativistic treatment of the dynamics, as is done in the CST, is necessary. The experimental data on the deuteron $A$ structure function extend to $Q simeq 12$ fm$^{-1}$, and the close agreement between these data and the CST results suggests that, even in this extreme kinematical regime, there is no evidence for new effects coming from quark and gluon degrees of freedom at short distances.
A Monte Carlo study for single baryon reconstruction method is presented based on two-body baryonic decays of charmonium, $jJ/psi$, $psi(3686)rightarrowXibarXi$ at BESIII experiment. As a result, we find that the detection efficiency for single baryon reconstruction method can be increased by a factor of $sim$4 relative to the traditional full-reconstruction method. It indicates that single baryon reconstruction method could be used in the other two-body baryonic decays of charmonium, such as $J/psi$, $psi(3686)rightarrowXi(1530)barXi(1530)$, $Xi(1530)barXi$, whose expected yields are estimated based on single baryon reconstruction method. The expected uncertainties for the measurements of the angular distribution parameters are also discussed.
We reconsider the derivation of the nucleon-nucleon parity-violating (PV) potential within a chiral effective field theory framework. We construct the potential up to next-to-next-to-leading order by including one-pion-exchange, two-pion-exchange, contact, and 1/M (M being the nucleon mass) terms, and use dimensional regularization to renormalize the pion-loop corrections. A detailed analysis of the number of independent low-energy constants (LECs) entering the potential is carried out. We find that it depends on six LECs: the pion-nucleon PV coupling constant $h^1_pi$ and five parameters multiplying contact interactions. We investigate PV effects induced by this potential on several few-nucleon observables, including the $vec{p}$-$p$ longitudinal asymmetry, the neutron spin rotation in $vec{n}$-$p$ and $vec{n}$-$d$ scattering, and the longitudinal asymmetry in the $^3$He$(vec{n},p)^3$H charge-exchange reaction. An estimate for the range of values of the various LECs is provided by using available experimental data.
We report on a recent calculation of the properties of the $DNN$ system, a charmed meson with two nucleons. The system is analogous to the $bar K NN$ system substituting a strange quark by a charm quark. Two different methods are used to evaluate the binding and width, the Fixed Center approximation to the Faddeev equations and a variational calculation. In both methods we find that the system is bound by about 200 MeV and the width is smaller than 40 MeV, a situation opposite to the one of the $bar K NN$ system and which makes this state well suited for experimental observation.
The authors present a technique using variational Monte Carlo to solve for excited states of electronic systems. The technique is based on enforcing orthogonality to lower energy states, which results in a simple variational principle for the excited states. Energy optimization is then used to solve for the excited states. An application to the well-characterized benzene molecule, in which ~10,000 parameters are optimized for the first 12 excited states.Agreement within approximately 0.15 eV is obtained with higher scaling coupled cluster methods; small disagreements with experiment are likely due to vibrational effects.
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