Muon Capture In Deuterium Research Articles

Calculation of doublet capture rate for muon capture in deuterium within chiral effective field theory

The doublet capture rate Λ1/2 of the negative muon capture in deuterium is calculated employing the nuclear wave functions generated from accurate nucleon–nucleon (NN) potentials constructed at next-to-next-to-next-to-leading order of heavy-baryon chiral perturbation theory and the weak meson exchange current operator derived within the same formalism. All but one of the low-energy constants that enter the calculation were fixed from pion–nucleon and nucleon–nucleon scattering data. The low-energy constant dˆR (cD), which cannot be determined from the purely two-nucleon data, was extracted recently from the triton β-decay and the binding energies of the three-nucleon systems. The calculated values of Λ1/2 show a rather large spread for the used values of the dˆR. Precise measurement of Λ1/2 in the future will not only help to constrain the value of dˆR, but also provide a highly nontrivial test of the nuclear chiral EFT framework. Besides, the precise knowledge of the constant dˆR will allow for consistent calculations of other two-nucleon weak processes, such as proton–proton fusion and solar neutrino scattering on deuterons, which are important for astrophysics.

Muon capture in deuterium

Model dependence of the capture rates of the negative muon capture in deuterium is studied starting from potential models and the weak two-body meson exchange currents constructed in the tree approximation and also from an effective field theory. The tree one-boson exchange currents are derived from the hard pion chiral Lagrangians of the N Δ π ρ ω a 1 system. If constructed in conjunction with the one-boson exchange potentials, the capture rates can be calculated consistently. On the other hand, the effective field theory currents, constructed within the heavy baryon chiral perturbation theory, contain a low energy constant d ˆ R that cannot be extracted from data at the one-particle level nor determined from the first principles. Comparative analysis of the results for the doublet transition rate allows us to extract the constant d ˆ R .

MUON CAPTURE IN DEUTERIUM

Muon capture in deuterium, μ-+ D →νμ+n+n, is a weak process of fundamental importance. The capture rate depends critically on the spin configuration of the initial (μ D ) state, which is in turn related closely to the availability of having two nearby deuteron nuclei. In this paper, we calculate the capture rates from the doublet [Formula: see text] and quartet [Formula: see text] hyperfine states. In addition to using the gaseous or liquid deuterium target, we wish also to propose to employ the deuterated target such as PdD or TiD to carry out the muon capture measurement, since it is known that the transition metals such as palladium (Pd) or titanium (Ti) has unusually high deuteron (hydrogen) absorption properties.

Muon capture in deuterium and the meson exchange current effect

One-meson exchange current effect in reaction μ − + d → 2 n + v μ is calculated by using the weak axial current operator which satisfies the nuclear continuity equation up to the order 1 M 2 ( M is the nucleon mass). In the vector part of the weak nuclear interaction the vector-isovector pion exchange currents are also included. Their contribution is found to be non-negligible. The nuclear wave functions are generated from the Paris, Reid soft-core and Bonn potential models. Our result is compatible with the previous one, obtained with only the static axial exchange currents included.

Exchange currents and extraction of ann and gP from negative MUON capture in deuterium

It is shown that the value of the neutron-neutron scattering length a nn extracted from the normalized differential neutron spectra measured in the reaction μ − + d → 2n + ν μ can be changed by up to ≈ −0.07 fm by the axial meson exchange current (MEC) effects, this being comparable in magnitude to the error in a nn due to the uncertainty of 0.2 fm in r nn. The kinematical region is found where the influence of these effects on the extraction of a nn is minimal. Due to the MEC effects, the value of g P obtained from the ratio of the quadruplet Γ q to the doublet Γ d transition rate is changed by ≈0.5 g A. We also confirm that the normalized neutron spectra are sensitive to a reasonably small variation of a nn.

Hard pions and axial meson exchange current effects in negative muon capture in deuterium

The contribution of the axial meson exchange current effects to the doublet transition rate in the reaction μ − + d → 2 n+ ν μ is calculated by using the minimal, chiral and approximately gauge invariant Lagrangian model for the A 1ρπ system. The contribution from the ρ-π weak decay process current usually considered is found to be nearly cancelled by that from the A 1 pole graph which is prescribed by the underlying invariance principles. Correct treatment of the N ∗ propagator in the N ∗ excitation current of the pion range leads to ≈ 30 % suppression of the N ∗ effect.

Muon capture in deuterium with realistic potentials

Abstract The transition rates for muon capture in deuterium are calculated using the Reid soft-core deuteron, and 1 S 0 and 3 P J (J = 0, 1, 2) neutron-neutron wave functions. The validity of the closure approximation and of the Omnes-Muskhelishvili method is studied. The off-shell effects admissible in a class of phase-shift-equivalent potentials by present experimental data are evaluated.

Muon-Capture Rates in Deuterium and the Weak Form Factors in the Timelike Region

The rates for muon capture in deuterium from the doublet and quartet states are calculated by the use of the elementary-particle treatment. The matrix elements of the vector and axial-vector currents are each constructed in terms of two independent form factors. The form factors describing the matrix element of the vector current are obtainesd in the spacelike region from electrodisintegration and photodisintegnation data by the use of the conserved- vector-current hypothesis. The form factors describing the matrix element of the axial-vector current are obtained in the spacelike region by the use of the hypothesis, of partial conversation of axial-vector current and arguments based on the impulse approximation. The capture rates are found to be sensitive to the behavior of the form factors near q/sup 2/ = m/sub mu //sup 2/. The capture rates from the doublet and quartet states are fou nd t, be GAMMA /sub d/ = 374 plus or minus 18 sec/sup -1/ and GAMMA /sub q/ = 6.07 plus or minus 0.04 sec/ sup muons plus :q1; muons minus :q1; gev range 10-100; It is shown that 25.6% of the contribution to GAMMA /sub d/ comes from the timelike region and that an analytic continuation of themore » dipole fit for the form factors to the timelike region from the spacelike region is consistent with experimental data. (auth)« less

Muon capture in deuterium

The muon capture in deuterium is studied by means of the impulse approximation with relativistic corrections. The deuteron is described by means of theS- andD-wave.

Relativistic treatment of muon capture in deuterium: Application to the determination of neutron-neutron scattering length and effective range

This paper is devoted to a relativistic calculation of muon capture in deuterium. The important effect of hyperfine structure is treated relativistically. The aim of this work is a determination of neutron-neutron scattering length and effective range. We use vertex functions to describe the proton-neutron-deuteron vertex and the Omnès method to compute the final-state interaction. It is shown that an accuracy of 2.5% in spectrum and capture rate must allow a determination of r os and a s with an accuracy of, respectively, ±0.2 fm and ±0.7 fm.