We investigate the existence of bound $Xi$ break states in systems with $A=4-7$ baryons using the Jacobi NCSM approach in combination with chiral NN and $Xi$N interactions. We find three shallow bound states for the NNN$Xi$ system (with $(J^pi,T)=(1^
+,0)$, $(0^+,1)$ and $(1^+,1)$) with quite similar binding energies. The $^5_{Xi}mathrm{H}(frac{1}{2}^+,frac{1}{2})$ and $^7_{Xi}mathrm{H}(frac{1}{2}^+,frac{3}{2})$ hypernuclei are also clearly bound with respect to the thresholds $^4mathrm{He} + Xi$ and $^6mathrm{He} +Xi$, respectively. The binding of all these $Xi$ systems is predominantly due to the attraction of the chiral $Xi$N potential in the $^{33}S_1$ channel. A perturbative estimation suggests that the decay widths of all the observed states could be rather small.
We utilize the experimentally known difference of the $Lambda$ separation energies of the mirror hypernuclei ${^4_Lambda rm He}$ and ${^4_Lambda rm H}$ to constrain the $Lambda$-neutron interaction. We include the leading charge-symmetry breaking (CS
B) interaction into our hyperon-nucleon interaction derived within chiral effective field theory at next-to-leading order. In particular, we determine the strength of the two arising CSB contact terms by a fit to the differences of the separation energies of these hypernuclei in the $0^+$ and $1^+$ states, respectively. By construction, the resulting interaction describes all low energy hyperon-nucleon scattering data, the hypertriton and the CSB in ${^4_Lambda rm He}$-${^4_Lambda rm H}$ accurately. This allows us to provide first predictions for the $Lambda$n scattering lengths, based solely on available hypernuclear data.
In this work, we analyze the semi-leptonic decays $bar B^0/D^0 to (a_0(980)^{pm}topi^{pm}eta) l^{mp} u$ within light-cone sum rules. The two and three-body light-cone distribution amplitudes (LCDAs) of the $B$ meson and the only available two-body L
CDA of the $D$ meson are used. To include the finite-width effect of the $a_0(980)$, we use a scalar form factor to describe the final-state interaction between the $pieta$ mesons, which was previously calculated within unitarized Chiral Perturbation Theory. The result for the decay branching fraction of the $D^0$ decay is in good agreement with that measured by the BESIII Collaboration, while the branching fraction of the $bar B^0$ decay can be tested in future experiments.
Based on our analysis of the contributions from the connected and disconnected contraction diagrams to the pion-kaon scattering amplitude, we provide the first determination of the low-energy constant $L_0^r$ in SU$(4|1)$ Partially-Quenched Chiral Pe
rturbation Theory from data of the Extended Twisted Mass Collaboration, $L_0^r = 0.51(26)cdot 10^{-3}$ at $mu=1$ GeV.
Electromagnetic form factors of hyperons ($Lambda$, $Sigma$, $Xi$) in the timelike region, accessible in the reaction $e^+e^- to bar YY$, are studied. The focus is on energies close to the reaction thresholds, where the properties of these form facto
rs are significantly influenced by the interaction in the final $bar YY$ system. This interaction is taken into account in the calculation, utilizing $bar YY$ potential models that have been constructed by the Julich group for the analysis of data from the reaction $bar pp to bar YY$ in the past. The enhancement of the effective form factor for energies close to the threshold, seen in experiments of $e^+e^- to bar Lambda Lambda$ and $e^+e^- to bar Sigma^0Lambda$, is reproduced. With regard to the reactions $e^+e^- to bar Sigma^- Sigma^+, barSigma^0Sigma^0, barSigma^+Sigma^-$ a delicate interplay between the three channels is observed in the results at low energies, caused by the $barSigmaSigma$ interaction. Predictions for the electromagnetic form factors $G_M$ and $G_E$ in the timelike region are presented for the $Lambda$, $Sigma$, and $Xi$ hyperons.
We extend the recently developed Jacobi no-core shell model to hypernuclei. Based on the coefficients of fractional parentage for ordinary nuclei, we define a basis where the hyperon is the spectator particle. We then formulate transition coefficient
s to states that single out a hyperon-nucleon pair which allow us to implement a hypernuclear many-baryon Hamiltonian for $p$-shell hypernuclei. As a first application, we use the basis states and the transition coefficients to calculate the ground states of $^{4}_{Lambda}$He, $^{4}_{Lambda}$H, $^{5}_{Lambda}$He, $^{6}_{Lambda}$He, $^{6}_{Lambda}$Li, and $^{7}_{Lambda}$Li and, additionally, the first excited states of $^{4}_{Lambda}$He, $^{4}_{Lambda}$H, and $^{7}_{Lambda}$Li. In order to obtain converged results, we employ the similarity renormalization group (SRG) to soften the nucleon-nucleon and hyperon-nucleon interactions. Although the dependence on this evolution of the Hamiltonian is significant, we show that a strong correlation of the results can be used to identify preferred SRG parameters. This allows for meaningful predictions of hypernuclear binding and excitation energies. The transition coefficients will be made publicly available as HDF5 data files.
In an earlier paper~cite{Luu:2019jmb} we discussed emergence from the context of effective field theories, particularly as related to the fields of particle and nuclear physics. We argued on the side of reductionism and weak emergence. George Ellis h
as critiqued our exposition in~cite{Ellis:2020vij}, and here we provide our response to his critiques. Many of his critiques are based on incorrect assumptions related to the formalism of effective field theories and we attempt to correct these issues here. We also comment on other statements made in his paper. Important to note is that our response is to his critiques made in archi
The static quadrupole moments (SQMs) of nuclear chiral doublet bands are investigated for the first time taking the particle-hole configuration $pi(1h_{11/2}) otimes u(1h_{11/2})^{-1}$ with triaxial deformation parameters in the range $260^circ leq
gamma leq 270^circ$ as examples. The behavior of the SQM as a function of spin $I$ is illustrated by analyzing the components of the total angular momentum. It is found that in the region of chiral vibrations the SQMs of doublet bands are strongly varying with $I$, whereas in the region of static chirality the SQMs of doublet bands are almost constant. Hence, the measurement of SQMs provides a new criterion for distinguishing the modes of nuclear chirality. Moreover, in the high-spin region the SQMs can be approximated by an analytic formula with a proportionality to $cosgamma$ for both doublet bands. This provides a way to extract experimentally the triaxial deformation parameter $gamma$ for chiral bands from the measured SQMs.
The effective field theory for collective rotations of triaxially deformed nuclei is generalized to odd-mass nuclei by including the angular momentum of the valence nucleon as an additional degree of freedom. The Hamiltonian is constructed up to next
-to-leading order within the effective field theory formalism. The applicability of this Hamiltonian is examined by describing the wobbling bands observed in the lutetium isotopes $^{161,163,165,167}$Lu. It is found that by taking into account the next-to-leading order corrections, quartic in the rotor angular momentum, the wobbling energies $E_{textrm{wob}}$ and spin-rotational frequency relations $omega(I)$ are better described than with the leading order Hamiltonian.
We study the contributions from the connected and disconnected contraction diagrams to the pion-kaon scattering amplitude within the framework of SU$(4|1)$ partially-quenched chiral perturbation theory. Combining this with a finite-volume analysis, w
e demonstrate that a lattice calculation of the easier computable connected correlation functions is able to provide valuable information of the noisier disconnected correlation functions, and may serve as a theory guidance for the future refinement of the corresponding lattice techniques.
