Conveners
WG3 parallel session
- Jambul Gegelia (Ruhr University Bochum)
WG3 parallel session
- Harald Griesshammer (Institute for Nuclear Studies, George Washington University)
WG3 parallel session
- Kimiko Sekiguchi (Tokyo Tech)
WG3 parallel session
- Hideyuki Sakai (RIKEN Nishina Center)
WG3 parallel session
- Emiko Hiyama (Tohoku Univ./RIKEN)
Any effective field theory relies on a certain power counting that allows one to perform a systematic expansion of calculated quantities in terms of some soft scales. However, a naive power counting can be violated due to the presence of various hard scales in the scheme. A typical example of such a scale is an ultraviolet regulator. This issue is particularly challenging when the...
Theorists love the unitarity limit: the $NN$ $S$-wave binding energies are zero, the scattering lengths infinite, and one has more symmetries. In "pionless" EFT, Efimov's $3N$ scale sets the only low-energy scale of all observables for a convergent, perturbative expansion around the unitarity limit. There are strong hints that Nuclear Physics resides indeed in a sweet spot: bound weakly enough...
The chiral Lagrangian provides a modern paradigm to build nuclear forces and nuclear currents for external probes. Higher-order chiral forces tend to have more complicated structures despite their smaller effects. We present our recent results in developing perturbatiion theories for higher-order chiral forces while iterating the leading-order interactions nonperturbatively. In particular, we...
Chiral effective field theory ($\chi$EFT) is an approach to describe the force between nucleons as arising from the more fundamental principles of quantum chromodynamics. A vital part is to have a power counting (PC) that quantifies the relative importance of the EFT order-by-order contributions to nuclear observables. The definition of the PC is not unique, and the fact that nuclear systems...
The leading and subleading three-pion exchange potentials have so far only been derived in chiral EFT by Norbert Kaiser using S-matrix matching. However, nuclear potentials are scheme-dependent quantities, and it is not a priori clear if the available results are consistent with the interactions and currents derived by the Bochum group using a different technique, the so-called Method of...
We study nucleon-nucleon interaction up to next-to-next-to-leading order (NNLO) by applying time-ordered perturbation theory (TOPT) to covariant chiral effective field theory. Diagrammatic rules of TOPT, for the first time, are worked out for particles with non-zero spin and interactions involving time derivatives. We define the effective potential as a sum of two-nucleon irreducible...
Hypernuclei provide important information to constrain the hyperon-nucleon (YN) and three-baryon (YNN) interactions. In this contribution, we will discuss our recent results obtained using chiral YN [1,2] and chiral YNN interactions for light hypernuclei up to $A=8$.
We use the hypernuclei data to determine the charge-symmetry breaking (CSB) of YN interactions and for exploring the results...
Study of isolated multi-neutron systems is one of fundamental subjects in nuclear physics. In several decades, experimental attempts have made with a particular focus on the tetra-neutron system. Among them, two experiments, the double-charge exchange reaction on ${}^4$He and the alpha-particle knockout reaction from the ${}^8$He, show a sharp peak structure just above the threshold in the...
Hyperon-proton scattering experiment is one of the most direct methods to study the hyperon-nucleon interaction, as in the case of the $NN$ interaction. Although it had been experimentally difficult for a long time due to short lifetime of hyperons, we successfully performed novel high-statistics $\Sigma^\pm p$ scattering experiment at J-PARC (J-PARC E40 experiment). The main physics...
It is important to study multi-neutron system for T=3/2 three nucleon force. For this purpose, I have been studying tetra neutron system, 7H etc. In this talk, I introduce recent study of these study. I also introduce my future study: up to 10-body system calculation with chral EFT force.
We have been performing calculations [1] using the SMS chiral potential [2] for NN interactions, the Juelich NLO19 chiral potential [3] for YN interactions, and the YNN three-body force [4] as inputs for the Faddeev three-body equations of Hypertriton. For the YNN three-body force, not only a two-pion exchange type but also one-pion exchange and contact types were adopted. Partial wave...
A reliable estimation of the accuracy of theoretical calculations is crucial for meaningful comparisons with experimental data. In the framework of chiral Effective Field Theory (EFT), one significant source of theoretical error stems from truncating the EFT expansion, which accounts for the impact of neglected higher-order terms. Past studies have typically estimated truncation uncertainty by...
Necessity of the three-nucleon forces (3NFs) have come to light in various nuclear phenomena, for example, binding energies of nuclei, and equation of state in nuclear matters. As numerically exact solutions of the Faddeev equations using 2N- and 3N-forces are now attainable for observables in nucleon-deuteron (Nd) scattering, intricate information of the 3NFs can be extracted by directly...
Three-nucleon systems offer fundamentals to determine the basic properties of three-nucleon forces (3NFs), such as the strength of the force. In contrast, many-nucleon systems are major playground of three-nucleon forces, as evidenced by, for example, spectroscopic properties of light nuclei, dripline determination, and nuclear-matter saturation.
In this presentation, we delve into the...
The ongoing progress in derivation the chiral two- and many-nucleon forces in the framework of chiral perturbation theory (χPT) [1,2] gives better and better understanding of nuclear phenomena, but also brings many challenges for application of these forces beyond the two-nucleon (2N) system. While general operator form of three nucleon force (3NF) is currently known up to N4LO [3-6], its...
Scattering experiments in systems of three nucleons provide particularly rich and sensitive data for testing the state-of-the-art potentials of nuclear interactions. Experimental studies of the deuteron breakup reaction demonstrated sensitivity of the observables to three-nucleon force (3NF) and but also the importance of the Coulomb interaction between protons even at beam energies close to...
We consider the three-nucleon system non-perturbatively in the framework of chiral effective field theory (EFT) on the lattice at next-to-next-to-next-to-leading order ($\mathrm{N^3LO}$). For the two-nucleon force, a lattice version of the successful semilocal momentum-space regularized (SMS) potential is employed. In the three-nucleon sector, we determine the two low-energy constants (LECs)...
Pionless effective field theory (EFT) represents a highly convenient tool that allows the description of nuclear interaction at very low energies. This theory, at its leading order, has been used to study various systems up to ${}^{16}$O; however, only with limited success, rendering $A > 4$ nuclei unbound in the large cutoff limit. Higher orders of the theory have been mostly tested in $A...
One of the fundamental problems in nuclear physics is to understand the properties of nuclei based on underlying nuclear interactions. The nuclear interactions determined with the few-body data can be tested by computing the heavier systems. The tested interactions can be used to predict the experimentally yet unknown properties. For this purpose, developing many-body techniques for heavier...
We present in this talk the most recent progresses made within the framework of chiral effective field theory for few-nucleon structure and low-energy reactions, especially those of astrophysical interest. We will first review the studies of the A=2 proton-proton fusion [1], as well as the muon capture on deuteron [2]. Furthermore, using the Hyperspherical Harmonics ab-initio method, we will...
Within the Generalized Contact Formalism [1], I will present a study of short-range correlations and contact coefficients [2], utilizing realistic chiral potentials, derived either in coordinate-space, and therefore local, or in momentum-space, and therefore non-local. Additionally, we employ the Hyperpherical Harmonics method [3] to calculate the two-body momentum distribution with virtually...
We use a combination of effective field theory and the renormalization group to determine the impact of radiative corrections on the nucleon-nucleon potential. In order to do so, we present a modified version of pionless effective field theory inspired by earlier work in nonrelativistic quantum electrodynamics. We investigate the effect of the corrections on the binding energy, electromagnetic...
Nuclear structure effects on the energies of light (ordinary and muonic) atoms are the dominant source of uncertainty in the determination of the nuclear charge radii and other properties of light nuclei [1], [2]. The most important of these effects are the two-photon exchange (TPE) contributions. The present method of choice for studying them is ab initio theoretical calculations. In this...
Charge, magnetic and Zemach radii of light nuclei characterize the distribution of electromagnetic charge inside the corresponding nuclei and are a perfect tool to test modern high-precision nuclear forces. Experimentally, these radii can be extracted from electron scattering and the laser spectroscopy of normal and muonic atoms with precision often reaching sub-percent level. Theoretical...
We study dark matter, assumed to be composed by weak interacting massive particles (WIMPs), scattering off ${}^2$H and ${}^4$He nuclei. In order to parameterize the WIMP-nucleon interaction the chiral effective field theory approach is used. Considering only interactions invariant under parity, charge conjugation and time reversal, we examine five interaction types: scalar, pseudoscalar,...
$\mu \to e$ conversion in nuclei gives one of the leading limits on BSM lepton-flavor violating (LFV) processes. Upcoming measurements call for a more consistent theoretical description of $\mu \to e$ conversion. This can be done model independently using an effective field theory framework in terms of effective BSM operators, which however crucially depends on hadronic and nuclear matrix...
The neutrinoless double beta decay $0\nu\beta\beta$ is of fundamental importance for particle physics, nuclear physics, and cosmology. The amplitude for the $0\nu\beta\beta$ decay of the two-neutron system $nn\rightarrow ppe^-e^-$ is a key building block to calculate the $0\nu\beta\beta$ decay in nuclei employed in large-scale experimental searches. Assuming that $0\nu\beta\beta$ decay is...
Neutrino oscillation measurements hint at non-zero neutrino masses, and the addition of gauge singlet right-handed neutrinos to the SM field content conveniently provides masses to the active neutrinos. A byproduct of this mechanism is the possible Majorana nature of neutrinos, which leads to lepton number violating effects, such as neutrinoless double beta decay. The standard study of these...
Parity-violating and time-reversal-violating (PVTV) nuclear interactions govern electric dipole moments of nuclei and play an important role in searches for beyond-Standard-Model physics. Recently, PVTV two- and three-nucleon potentials have been worked out to next-to-next-to-leading order in the chiral effective field theory (EFT) expansion based on pions and nucleons as the only explicit...
In this talk I will discuss the dependence of the primordial nuclear abundances as a function of fundamental physical constants like the electromagnetic fine-structure constant $\alpha$ and the Higgs VEV $v$. We updated the leading nuclear reaction rates and used more recent results for the electromagnetic and strong contribution to the neutron-proton mass difference. For the...
