Order In Chiral Expansion Research Articles

Impact of the N4LO\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {N}^4\\hbox {LO}$$\\end{document} Short-Range Three-Nucleon Force Components on the Nucleon-Deuteron Spin Correlation Coefficients

The spin correlation coefficients in the neutron-deuteron elastic scattering process at incoming neutron laboratory energies E=10\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {E}=10$$\\end{document}, 135, 190, and 250 MeV are determined by solving the momentum space three-nucleon (3N) Faddeev equations. The chiral two-nucleon (2N) interaction with momentum-space semi-local (SMS) regularization up to the fifth order of chiral expansion (N4LO\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {N}^4\\hbox {LO}$$\\end{document}), supplemented by the F-waves terms from the sixth order (N5LO\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {N}^5\\hbox {LO}$$\\end{document}), is used. Additionally, the consistent 3N force (3NF) at the third order of chiral expansion, supplemented by the short-range contributions from N4LO\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {N}^4\\hbox {LO}$$\\end{document} is applied. As a results, we give predictions for the complete set of spin correlation coefficients Cα,β\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_{\\alpha ,\\beta }$$\\end{document}. We find that the effect of the investigated three-nucleon N4LO\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {N}^4\\hbox {LO}$$\\end{document} components amounts up to several dozen percent, depending on reaction energy, scattering angle and type of spin correlation coefficient itself. Our results can serve as a guide for future measurements of the spin correlation coefficients.

Modern Chiral Forces Applied to the Neutron-Deuteron Breakup Reaction

We report on applications of the recent chiral potentials from the Bochum-Bonn group to the description of the neutron induced deuteron breakup observables. Specifically, we discuss the convergence of predictions with respect to the chiral order and the dependence of our results on the value of the regularization parameter. To that end we use the chiral forces with semi-local coordinate or momentum space regularization up to the N^4LO^+ order of chiral expansion. We find a satisfactory picture revealing high quality of the chiral forces used.

Spectroscopy of excited charmed mesons

We derive mass formulas for the $P$-wave orbitally excited $D^*_{0(s)}$, $D^\prime_{1(s)}$, $D_{1(s)}$, and $D^*_{2(s)}$ heavy charmed mesons including all effects from one-loop corrections that contribute at leading order in chiral expansion. In our formalism, the effects to first order in $m_q$, where $m_q$ is the light quark mass, and to first order in $m^{-1}_c$, where $m_c$ is the charm quark mass, and $m_q/m_c$ terms are considered. The experimental and lattice QCD results on the charmed meson spectra are employed to fix the large number of counterterms appearing in the effective chiral Lagrangian used in this work. This allows us to test the validity of perturbative expansion of our theory. The results presented in the current paper are useful to other applications of excited charmed and bottom meson systems.

Modern Chiral Forces Applied to the Nucleon\u2013Deuteron Radiative Capture

The chiral nucleon–nucleon interaction with semi-local regularization up to the fifth order of chiral expansion is applied to the nucleon–deuteron radiative capture process. Our theoretical approach is based on the formalism of Faddeev equations and the Siegert theorem is exploited to construct the electromagnetic current operator. The very weak dependence of the differential cross section on values of the regularization parameter is observed. This suggests that the improved chiral two-body interaction is a promising starting point to study electromagnetic processes at low energies.

On kaonic hydrogen. Phenomenological quantum field theoretic model revisited

We argue that due to isospin and U-spin invariance of strong low-energy interactions the S-wave scattering lengths a^0_0 and a^1_0 of bar-KN scattering with isospin I=0 and I = 1 satisfy the low-energy theorem a^0_0 + 3 a^1_0 = 0 valid to leading order in chiral expansion. In the model of strong low-energy bar-KN interactions at threshold (EPJA 21,11 (2004)) we revisit the contribution of the Sigma(1750) resonance, which does not saturate the low-energy theorem a^0_0 + 3 a^1_0 = 0, and replace it by the baryon background with properties of an SU(3) octet. We calculate the S-wave scattering amplitudes of K^-N and K^-d scattering at threshold. We calculate the energy level displacements of the ground states of kaonic hydrogen and kaonic deuterium. The result obtained for kaonic hydrogen agrees well with recent experimental data by the DEAR Collaboration. We analyse the cross sections for elastic and inelastic K^-p scattering for laboratory momenta of the incident K^- meson from the domain 70 MeV/c < p_K < 150 MeV/c. The theoretical results agree with the available experimental data within two standard deviations.

EFT for electroweak processes of light nuclei

Recently we succeeded to make a reliable EFT prediction in a totally parameter-free manner for the S factors for the solar pp and hep processes, p + p → d + e + + ν e and 3 He + p → 4 He + e + + ν e [1]. The strategy used in there is to embed a highly sophisticated standard nuclear physics approach (SNPA) exploiting realistic potentials[2,3] into an EFT framework, that we refer to as EFT∗. Up to next-next-to-leading order in chiral expansion, it turnes out that there is effectively only one counter-term relevant to this process, the coefficient of which − ( d ̂ R ) − has been renormalized to reproduce the experimental value of the tritium-beta decay. Our study has also led to very accurate EFT calculations on two-body weak processes that also receive contributions from the d ̂ R term, μ − d capture rate[4], and ν − d scattering cross section[5].

EFT for electroweak processes of light nuclei

Recently we succeeded to make a reliable EFT prediction in a totally parameter-free manner for the S factors for the solar pp and hep processes, p + p → d + e + + ν e and 3 He + p → 4 He + e + + ν e [1]. The strategy used in there is to embed a highly sophisticated standard nuclear physics approach (SNPA) exploiting realistic potentials[2,3] into an EFT framework, that we refer to as EFT∗. Up to next-next-to-leading order in chiral expansion, it turnes out that there is effectively only one counter-term relevant to this process, the coefficient of which − ( d ̂ R ) − has been renormalized to reproduce the experimental value of the tritium-beta decay. Our study has also led to very accurate EFT calculations on two-body weak processes that also receive contributions from the d ̂ R term, μ − d capture rate[4], and ν − d scattering cross section[5].

K → ππ matrix elements beyond the leading-order chiral expansion

We propose an approach for calculating K → ππ decays to the next-to-leading order in chiral expansion. A detailed numerical study of this approach is being performed.

π−p atom in ChPT: strong energy-level shift

The general formula of the π − p atom strong energy-level shift in the 1 s state is derived in the next-to-leading order in the isospin breaking, and in all orders in chiral expansion. Isospin-breaking corrections to the level shift are explicitly evaluated at order p 2 in ChPT. The results clearly demonstrate the necessity to critically reaccess the values of the πN scattering lengths, extracted from the energy-level shift measurement by means of the potential model-based theoretical analysis.

From kaon-nuclear interactions to kaon condensation

An effective chiral lagrangian in heavy-fermion formalism whose parameters are constrained by kaon-nucleon and kaon-nuclear interactions next to the leading order in chiral expansion is used to describe kaon condensation in dense “neutron star” matter. The critical density is found to be robust with respect to the parameters of the chiral lagrangian and is found to be ρ c~ (3–4)ρ 0. Once kaon condensation sets in, the system is no longer composed of neutron matter but of nuclear matter. Possible consequences on stellar collapse with the formation of compact “nuclear stars” or light mass black holes are pointed out.