SciPost: SciPost Physics Proceedings: issue detail

SciPost Physics Proceedings issue 3

24th European Few Body Conference (EFB2019)

Event dates: from 2019-09-02 to 2019-09-06.

This is the 24th edition of European Few Body Conference. Like the previous conferences, this conference will focus on recent developments in the field of few-body systems - that is, systems which can be understood in terms of a few effective degrees of freedom.

This Conference will focus on recent experimental and theoretical developments in the field of few-body systems, in areas such as:

Hadrons and particles
Nuclei and hypernuclei
Electroweak processes
Atoms and molecules
Cold atoms and quantum gases
Few-body methods

Nota bene: for submissions, please follow these length limitations: invited talks: 14 pages; contributed talks: 10 pages; posters: 6 pages.

(Guest) Fellows responsible for this Issue

Dr Alexis Diaz-Torres
Dr Arnau Rios Huguet
Prof. Paul Stevenson

Exotic structures in exotic nuclei

F. Miguel Marqués

SciPost Phys. Proc. 3, 001 (2020) · published 24 February 2020 | · pdf

Nuclei with proton and neutron numbers away from stability are known as exotic, and provide stringent tests of nuclear models, mainly developed for the description of stable nuclei. However, only the most extreme combinations lead to literally exotic structures, with sometimes unexpected properties. In this contribution we review some selected examples around the neutron dripline of very light elements: neutron halo structures with embedded substructures in the boron chain; the emission of neutron pairs in $^{16}$Be; and the existence of multi-neutron resonances in `superheavy' hydrogen isotopes.
Investigations of the few-nucleon systems within the LENPIC project

Jacek Golak, Evgeny Epelbaum, Alessandro Grassi, Hiroyuki Kamada, Hermann Krebs, Patrick Reinert, Roman Skibiński, Volodymyr Soloviov, Kacper Topolnicki, Vitalii Urbanevych, Yuriy Volkotrub, Henryk Witała

SciPost Phys. Proc. 3, 002 (2020) · published 24 February 2020 | · pdf

Results presented in this contribution are obtained within the Low Energy Nuclear Physics International Collaboration (LENPIC). LENPIC aims to develop chiral nucleon-nucleon and many-nucleon interactions complete through at least the fourth order in the chiral expansion. These interactions will be used together with consistently derived current operators to solve the structure and reactions of light and medium-mass nuclei including electroweak processes. In this contribution the current status of the chiral nuclear forces and current operators will be briefly discussed. A special role played by the calculations of nucleon-deuteron scattering will be explained.
Derivation of relativistic Yakubovsky equations under Poincaré invariance

Hiroyuki Kamada

SciPost Phys. Proc. 3, 003 (2020) · published 24 February 2020 | · pdf

Relativistic Faddeev-Yakubovsky four-nucleon scattering equations are derived including a 3-body force. We present these equations in the momentum space representation. The quadratic integral equations using the iteration method, in order to obtain boosted potentials and 3-body force, are demonstrated.
Measurement of spin correlation coefficients p-$^{3}$He scattering at 65 MeV

M. Inoue, K. Sekiguchi, K. Miki, A. Watanabe, S. Nakai, S. Shibuya, D. Sakai, Y. Utsuki, H. Umetsu, K. Hatanaka, H. Kanda, H. J. Ong, T. Wakasa, S. Goto, S. Mitsumoto, D. Inomoto, H. Kasahara, T. Ino, H. Sakai, Y. Maeda, K. Nonaka, T. Wakui, M. Itoh

SciPost Phys. Proc. 3, 004 (2020) · published 24 February 2020 | · pdf

We performed the experiment of p–$^{3}$He scattering at 65 MeV by using polarized proton beams and the newly constructed polarized $^{3}$He target. The proton analyzing power $A_{y}$, the 3He analyzing power $A^{T}_{y}$, and the spin correlation coefficient $C_{yy}$ were measured. In the conference, the experimental data were compared with the rigorous numerical calculations based on various nuclear potentials. Large discrepancies between the experimental data and the calculations were found in the $A^{T}_{y}$ and the $C_{yy}$ at the backward angles.
Current stage of studies of the star configurations at intermediate energies with the use of the BINA detector

A. Wilczek, A. Szadzinski, K. Bodek, I. Ciepal, M. Eslami-Kalantari, N. Kalantar-Nayestanaki, G. Khatri, St. Kistryn, B. Klos, A. Kozela, J. Kubos, P. Kulessa, A. Lobejko, A. Magiera, H. Mardanpour, J. Messchendorp, I. Mazumdar, W. Parol, A. Ramazani-Moghaddam-Aran, R. Ramazani-Sharifabadi, D. Rozpedzik, I. Skwira-Chalot, E. Stephan, B. Wloch, A. Wronska, J. Zejma

SciPost Phys. Proc. 3, 005 (2020) · published 24 February 2020 | · pdf

The Space Star Anomaly in proton-deuteron breakup cross-section occurs at energies of about 10 MeV. Data for higher energies are sparse. Therefore, a systematic scan over star configurations in the range of intermediate energies between 50 and 100 MeV/nucleon is carried out on the basis of data collected with the large acceptance BINA detector. The preliminary cross section results for forward star configurations at 80 MeV/nucleon slightly surpass the theoretical calculations, but the systematic uncertainties are still under study. Also, a new variable describing rotation of star configurations is proposed.
Determination of phase space region for cross-check validation of the neutron detection in the BINA experiments

B. Włoch, K. Bodek, I. Ciepał, M. Eslami-Kalantari, J. Golak, N. Kalantar-Nayestanaki, G. Khatri, St. Kistryn, B. Kłos, A. Kozela, J. Kuboś, P. Kulessa, A. Łobejko, A. Magiera, H. Mardanpour, J. Messchendorp, I. Mazumdar, W. Parol, A. Ramazani-Moghaddam-Arani, D. Rozpędzik, R. Skibiński, I. Skwira-Chalot, E. Stephan, A. Wilczek, H. Witała, A Wrońska, J. Zejma

SciPost Phys. Proc. 3, 006 (2020) · published 24 February 2020 | · pdf

Deuteron breakup reactions are basic laboratories for testing nuclear force models. Recent improvements in the data analysis allow for direct identification of neutrons in the BINA detection setup. This opens up the opportunity to study new aspects of few-nucleon system dynamics like charge dependence of nuclear force or Coulomb interaction. In this paper we determine regions along the kinematical curves where differential cross section of deuteron-proton breakup reactions can be measured by the proton-neutron and proton-proton coincidences simultaneously. This is particularly useful for validation of the neutron detection technique.
Impact of uncertainties of unbound 10Li on the ground state of two-neutron halo 11Li

Jagjit Singh, Wataru Horiuchi

SciPost Phys. Proc. 3, 007 (2020) · published 24 February 2020 | · pdf

Recently, the energy spectrum of 10Li was measured upto 4.6 MeV, via one-neutron transfer reaction d(9Li, p)10Li. Considering the ambiguities on the 10Li continuum spectrum with reference to new data, we report the con guration mixing in the ground state of the two-neutron halo nucleus 11Li for two different choices of the 9Li+n potential. For the present study, we employ a three-body (core+n+n) structure model developed for describing the two-neutron halo system by explicit coupling of unbound continuum states of the subsystem (core+n), and discuss the two-neutron correlations in the ground state of 11Li.
Low-energy neutron scattering on light nuclei and $^{19}$B as a $^{17}$B-$n$-$n$ three-body system in the unitary limit

Jaume Carbonell, Emiko Hiyama, Rimantas Lazauskas, F. Miguel Marqués

SciPost Phys. Proc. 3, 008 (2020) · published 24 February 2020 | · pdf

We consider the evolution of the neutron-nucleus scattering length for the lightest nuclei. We show that, when increasing the number of neutrons in the target nucleus, the strong Pauli repulsion is weakened and the balance with the attractive nucleon-nucleon interaction results into a resonant virtual state in $^{18}$B. We describe $^{19}$B in terms of a $^{17}$B-$n$-$n$ three-body system where the two-body subsystems $^{17}$B-$n$ and $n$-$n$ are unbound (virtual) states close to the unitary limit. The energy of $^{19}$B ground state is well reproduced and two low-lying resonances are predicted. Their eventual link with the Efimov physics is discussed. This model can be extended to describe the recently discovered resonant states in $^{20,21}$B.
Clustering in $^{18}$O - absolute determination of branching ratios via high-resolution particle spectroscopy

S. Pirrie, C. Wheldon, Tz. Kokalova, J. Bishop, R. Hertenberger, H.-F. Wirth, S.~Bailey, N. Curtis, D. Dell'Aquila, Th. Faestermann, D. Mengoni, R. Smith, D.Torresi, A. Turner

SciPost Phys. Proc. 3, 009 (2020) · published 24 February 2020 | · pdf

The determination of absolute branching ratios for high-energy states in light nuclei is an important and useful tool for probing the underlying nuclear structure of individual resonances: for example, in establishing the tendency of an excited state towards $\alpha$-cluster structure. Difficulty arises in measuring these branching ratios due to similarities in available decay channels, such as ($^{18}$O,$n$) and ($^{18}$O,$2n$), as well as differences in geometric efficiencies due to population of bound excited levels in daughter nuclei. Methods are presented using Monte Carlo techniques to overcome these issues.
Short range nucleon correlations studied with electron and photon probes

I.J. Douglas MacGregor

SciPost Phys. Proc. 3, 010 (2020) · published 24 February 2020 | · pdf

This paper reviews experimental research into two- and three-body nucleon-nucleon interactions, carried out by the University of Glasgow Nuclear Physics research group. A key aim of these studies has been to elucidate the role of short-range nucleon-nucleon correlations (SRC). Studies of photon-induced two- and three-nucleon emission reactions from a range of light nuclei, carried out at the 840 MeV Mainz electron microtron MAMI-B, have provided detailed information on the contributing mechanisms. More recent electron scattering studies at the 6.0 GeV Jefferson Laboratory have probed SRC at high values of Q2 and xB and suggested a connection between SRC and the EMC effect.
Latest results concerning short range correlations obtained in the dp elastic and dp breakup processes at Nuclotron, JINR

Marian Janek, Vladimir P. Ladygin, Alexander V. Averyanov, Eugene V. Chernykh, Dan D. Enache, Yuri V. Gurchin, Alexandr Yu. Isupov, Julia-Tatiana Karachuk, Anatoly N. Khrenov, Dimitry O. Krivenkov, Pavel K. Kurilkin, Nadezhda B. Ladygina, Alexei N. Livanov, Olena Mezhenska, Semen M. Piyadin, Sergei G. Reznikov, Yaroslav T. Skhomenko, Arkady A. Terekhin, Alexei V. Tishevsky, Tomohiro Uesaka

SciPost Phys. Proc. 3, 011 (2020) · published 24 February 2020 | · pdf

Deuteron spin structure program is aimed on extraction of two and three nucleon forces information, including their spin dependent parts, from dp elastic and dp breakup processes investigated at intermediate energies. The dp elastic data were obtained at Internal Target Station of Nuclotron (JINR) in the energy range 400-1800 MeV using polarized deuteron beam. Strong sensitivity to the short range spin structure of the isoscalar nucleon-nucleon correlations is observed in deuteron analyzing powers. Preliminary results of the the cross section for the dp breakup reaction have been obtained at 400 MeV of deuteron energy.
Theoretical study of deeply virtual Compton scattering off $^4$He

Sara Fucini, Sergio Scopetta, Michele Viviani

SciPost Phys. Proc. 3, 012 (2020) · published 24 February 2020 | · pdf

An interesting breakthrough in understanding the elusive inner content of nuclear systems in terms of partonic degrees of freedom is represented by deeply virtual Compton scattering processes. In such a way, tomographic view of nuclei and bound nucleons in coordinate space could be achieved for the first time. Moreover, nowadays experimental results for such a process considering $^4$He targets recently released at Jefferson Lab are available. In this talk, the recent results of our rigorous Impulse Approximation for DVCS off $^4$He, in terms of state-of-the-art models of the nuclear spectral function and of the parton structure of the bound proton, able to explain present data, has been shown.
The charged $Z_c$ and $Z_b$ structures in a constituent quark model approach

Pablo Garcia Ortega, Jorge Segovia, David Rodriguez Entem and Francisco Fernández

SciPost Phys. Proc. 3, 013 (2020) · published 25 February 2020 | · pdf

The nature of the recently discovered $Z_c$ and $Z_b$ structures is intriguing. Their charge forces its minimal quark content to be $Q\bar Q q\bar q$ (where $Q=\{c,b\}$ and $q=\{u,d\}$). In this work we perform a molecular coupled-channels calculation of the $I^G(J^{PC})=1^+(1^{+-})$ charm and bottom sectors in the framework of a constituent quark model which satisfactorily describes a wide range of properties of (non-)conventional hadrons containing heavy quarks. All the relevant channels are included for each sector, i.e.: The $D^{(\ast)}\bar D^{\ast}+h.c.$, $\pi J/\psi$ and $\rho\eta_c$ channels for the $Z_c$ and $B^{(\ast)}B^{\ast}$ and $\Upsilon(nS)\pi$ ($n=1,2,3$) channels for the $Z_b$ analysis. Possible structures of these resonances will be discussed
Generalized parton distribution functions of $\rho$ meson

Baodong Sun, Yubing Dong

SciPost Phys. Proc. 3, 014 (2020) · published 25 February 2020 | · pdf

We report our recent calculations for the generalized parton distribution functions of the $\rho$ meson with the help of a light-front constituent quark model. The electromagnetic form factors and structure functions of the system are given. Moreover, we also show our results for its gravitational form factors (or energy-momentum tensor form factors) and for other mechanical properties, like its mass distributions, pressures, share-forces, and $D-$term.
Recent progress on the study of nucleon structure from lattice QCD and future perspectives

Constantia Alexandrou

SciPost Phys. Proc. 3, 015 (2020) · published 25 February 2020 | · pdf

We review the progress achieved within the last five years in the simulations of lattice QCD, as well as in the analysis for selected quantities probing nucleon structure. In particular, we discuss results on the nucleon electromagnetic form factors, $\sigma$-terms, the momentum fraction carried b quark in the nucleon and the helicity and transversity. All quantities are obtained using simulations generated with quark masses fixed to their physical values. In addition, we review the on-going effort to extract parton distribution functions (PDFs) directly from lattice QCD using the quasi-PDFs approach.
Roy Glauber and asymptotic diffraction theory

Per Osland

SciPost Phys. Proc. 3, 016 (2020) · published 25 February 2020 | · pdf

This is a review of Glauber's asymptotic diffraction theory, in which diffractive scattering is described in terms of interference between semiclassical amplitudes, resulting from a stationary-phase approximation. Typically two such amplitudes are sufficient to accurately describe elastic scattering, but the stationary points are located at complex values of the impact parameter. Their separation controls the interference pattern, and their offsets from the real axis determine the overall fall-off with momentum transfer. Asymptotically, at large momentum transfers, the stationary points move towards singularities of the profile function. I also include some reminiscences from our collaboration.
The eikonal model of reactions involving exotic nuclei; Roy Glauber's legacy in today's nuclear physics

Pierre Capel

SciPost Phys. Proc. 3, 017 (2020) · published 25 February 2020 | · pdf

In this contribution, the eikonal approximation developed by Roy Glauber to describe high-energy quantum collisions is presented. This approximation has been-and still is-extensively used to analyse reaction measurements performed to study the structure of nuclei far from stability. This presentation focuses more particularly on the application of the eikonal approximation to the study of halo nuclei in modern nuclear physics. To emphasise Roy Glauber's legacy in today's nuclear physics, recent extensions of this model are reviewed.
Few-nucleon system dynamics studied via deuteron-deuteron collisions at 160 MeV

I. Ciepał , K. Bodek, N. Kalantar-Nayestanaki , G. Khatri , St. Kistryn , B. Kłos, A. Kozela , J. Kuboś, P. Kulessa , A. Łobejko, A. Magiera , J. Messchendorp , I. Mazumdar, W. Parol , R. Ramazani-Sharifabadi, D. Rozpędzik , I. Skwira-Chalot , E. Stephan, A. Wilczek , B. Włoch, A. Wrońska , J. Zejma

SciPost Phys. Proc. 3, 018 (2020) · published 25 February 2020 | · pdf

Four nucleon scattering at intermediate energies provides unique opportunities to study effects of the two key ingredients of the nuclear dynamics, the nucleon-nucleon P-wave (NNP-wave) and the three-nucleon force (3NF). This is possible only with systematic and precise data, in conjunction with exact theoretical calculations. Using the BINA detector at KVI Groningen, the Netherlands, a rich set of differential cross section of the 2H(d, dp)n breakup reaction at 160 MeV deuteron beam energy has been measured. Besides the three-body breakup, also cross sections of the 2H(d, 3He)n proton transfer reaction have been obtained. The data are compared to the recent calculations for the three-cluster breakup.
Measurement for p–3He elastic scattering with a 65 MeV polarized proton beam

S. Nakai, K. Sekiguchi, K. Miki, A. Watanabe, S. Shibuya, M. Watanabe, K. Kawahara, D. Sakai, Y. Wada, H. Umetsu, M. Itoh, K. Hatanaka, A. Tamii, N. Kobayashi, A. Inoue, S. Nakamura, T. Wakasa, S. Mitsumoto, H. Ohshiro, S. Goto, Y. Maeda, H. Sakai

SciPost Phys. Proc. 3, 019 (2020) · published 25 February 2020 | · pdf

We measured the cross section and the proton analyzing power Ay for p–3He elastic scattering at the angles θ = 26.9◦–170.1◦ in the center of mass system with a 65 MeV polarized proton beam. We compared the data with the rigorous numerical calculations based on the various nucleon–nucleon potentials. For the cross section, clear discrepancy is seen at the angles where the cross section takes minimum. For the proton analyzing power Ay, the calculations have moderate agreements to the data. In this proceedings, we show only the experimental results.
Measurement of 3He analyzing power for p-3He scattering using the polarized 3He target

A. Watanabe, S. Nakai, K. Sekiguchi, T. Akieda, D. Etoh, M. Inoue, Y. Inoue, K. Kawahara, H. Kon, K. Miki, T. Mukai, D. Sakai, S. Shibuya, Y. Shiokawa, T. Taguchi, H. Umetsu, Y. Utsuki, Y. Wada, M. Watanabe, M. Itoh, T. Ino, T. Wakui, K. Hatanaka, H. Kanda, H. J. Ong, D. T. Tran, S. Goto, Y. Hirai, D. Inomoto, H. Kasahara, S. Mitsumoto, H. Oshiro, T. Wakasa, Y. Maeda, K. Nonaka, H. Sakai, T. Uesaka

SciPost Phys. Proc. 3, 020 (2020) · published 25 February 2020 | · pdf

Proton–3He scattering is one of the good probes to study the T = 3/2 channel of three– nucleon forces. We have measured 3He analyzing powers for p−3He elastic scattering with the polarized 3He target at 70 and 100 MeV. In the conference the data were com- pared with the theoretical predictions based on the modern nucleon–nucleon potentials. Large discrepancies were found between the data and the calculations at the angles where the 3He analyzing power takes the minimum and maximum values.
Influence of the Pauli principle on two-cluster potential energy

Yuliya A. Lashko, Victor S. Vasilevsky, Gennady F. Filippov

SciPost Phys. Proc. 3, 021 (2020) · published 25 February 2020 | · pdf

We study effects of the Pauli principle on the potential energy of two-cluster systems. The object of the investigation is the lightest nuclei of p-shell with a dominant $\alpha$-cluster channel. For this aim we construct matrix elements of two-cluster potential energy between cluster oscillator functions with and without full antisymmetrization. Eigenvalues and eigenfunctions of the potential energy matrix are studied in detail. Eigenfunctions of the potential energy operator are presented in oscillator, coordinate and momentum spaces. We demonstrate that the Pauli principle affects more strongly the eigenfunctions than the eigenvalues of the matrix and leads to the formation of resonance and trapped states.
Electric-dipole transitions in 6Li with a fully microscopic six-body calculation

Wataru Horiuchi, Shuji Satsuka

SciPost Phys. Proc. 3, 022 (2020) · published 25 February 2020 | · pdf

Exploring new excitation modes and the role of the nuclear clustering has been of great interest. An interesting speculation was made in the recent photoabsorption measurement of 6Li that implied the importance of the nuclear clustering. To understand the excitation mechanism of 6Li, we perform a fully microscopic six-body calculation on the electric-dipole (E1) transitions and discuss how 6Li is excited by the E1 field as a function of the excitation energy. We show the various cluster components in the six-body wave functions and discuss the role of the nuclear clustering in the E1 excitations of 6Li.
Dipolar condensed atomic mixtures and miscibility under rotation

Lauro Tomio, R. Kishor Kumar, Arnaldo Gammal

SciPost Phys. Proc. 3, 023 (2020) · published 25 February 2020 | · pdf

By considering symmetric and asymmetric dipolar coupled mixtures (with dysprosium and erbium isotopes), we report a study on relevant anisotropic effects, related to spatial separation and miscibility, due to dipole-dipole interactions (DDIs) in rotating binary dipolar Bose-Einstein condensates. The binary mixtures are kept in strong pancake-like traps, with repulsive two-body interactions modeled by an effective two-dimensional (2D) coupled Gross-Pitaevskii equation. The DDI are tuned from repulsive to attractive by varying the dipole polarization angle. A clear spatial separation is verified in the densities for attractive DDIs, being angular for symmetric mixtures and radial for asymmetric ones. Also relevant is the mass-imbalance sensibility observed by the vortex-patterns in symmetric and asymmetric-dipolar mixtures. In an extension of this study, here we show how the rotational properties and spatial separation of these dipolar mixture are affected by a quartic term added to the harmonic trap of one of the components.
Fluctuations of work in realistic equilibrium states of quantum systems with conserved quantities

Jordi Mur-Petit, Armando Relaño, Rafael A. Molina, Dieter Jaksch

SciPost Phys. Proc. 3, 024 (2020) · published 25 February 2020 | · pdf

The out-of-equilibrium dynamics of quantum systems is one of the most fascinating problems in physics, with outstanding open questions on issues such as relaxation to equilibrium. An area of particular interest concerns few-body systems, where quantum and thermal fluctuations are expected to be especially relevant. In this contribution, we present numerical results demonstrating the impact of conserved quantities (or ‘charges’) in the outcomes of out-of-equilibrium measurements starting from realistic equilibrium states on a few-body system implementing the Dicke model.
Exploring the unknown Lambda-neutron interaction

Benjamin F. Gibson, Iraj. R. Afnan

SciPost Phys. Proc. 3, 025 (2020) · published 25 February 2020 | · pdf

No published Λn scattering data exist. A relativistic heavy-ion experiment has suggested that a Λnn bound state was seen. However, several theoretical analyses have cast serious doubt on the bound-state assertion. Nevertheless, there could exist a three-body Λnn resonance. Such a resonance could be used to constrain the Λn interaction. We dis- cuss Λnn calculations using nn and Λn pairwise interactions of rank-one, separable form that fit effective range parameters of the nn system and those hypothesized for the as yet unobserved Λn system based upon four different ΛN potentials. The use of rank-one separable potentials allows one to analytically continue the Λnn Faddeev equations onto the second complex energy plane in search of resonance poles, by examining the eigenvalue spectrum of the kernel of the Faddeev equations. Although each of the potential models predicts a Λnn sub-threshold resonance pole, scaling of the Λn interaction by as little as ∼5% does produce a physical resonance. This suggests that one may use photo- (electro-)production of the Λnn system from tritium as a tool to examine the strength of the Λn interaction.
Study of the hyperon-nucleon interaction via final-state interactions in exclusive reactions

Nicholas Zachariou, Daniel Watts, Yordanka Ilieva

SciPost Phys. Proc. 3, 026 (2020) · published 25 February 2020 | · pdf

A novel approach that allows access to long-sought information on the Hyperon-Nucleon (YN) interaction was developed by producing a hyperon beam within a few-body nuclear system, and studying final-state interactions. The determination of polarisation observables, and specifically the beam spin asymmetry, in exclusive reactions allows a detailed study of the various final-state interactions and provides us with the tools needed to isolate kinematic regimes where the YN interaction dominates. High-statistics data collected using the CLAS detector housed in Hall-B of the Thomas Jefferson laboratory allows us to obtain a large set of polarisation observables and place stringent constraints on the underlying dynamics of the YN interaction.
Hyperons - a strange key to the strong interaction

Karin Schoenning

SciPost Phys. Proc. 3, 027 (2020) · published 25 February 2020 | · pdf

Hyperons provide new angles on two of the most challenging problems in contempo- rary physics: a coherent and quantitative description of the strong interaction, and the matter-antimatter asymmetry of the Universe. In these proceedings, I will demonstrate the merits of hyperons as a diagnostic tool using two recent measurements by the BE- SIII experiment as an illustrative example. Furthermore, I will highlight the prospect of future hyperon studies with the next-generation experiment PAND
Muonic Lithium atoms: nuclear structure corrections to the Lamb shift

Simone Salvatore Li Muli, Anna Poggialini, Sonia Bacca

SciPost Phys. Proc. 3, 028 (2020) · published 25 February 2020 | · pdf

In view of the future plans to measure the Lamb shift in muonic Lithium atoms we address the microscopic theory of the $\mu$-$^6$Li$^{2+}$ and $\mu$-$^7$Li$^{2+}$ systems. The goal of the CREMA collaboration is to measure the Lamb shift to extract the charge radius with high precision and compare it to electron scattering data or atomic spectroscopy to see if interesting puzzles, such as the proton and deuteron radius puzzles, arise. For this experiment to be successful, theoretical information on the nuclear structure corrections to the Lamb shift is needed. For $\mu$-$^6$Li$^{2+}$ and $\mu$-$^7$Li$^{2+}$ there exist only estimates of nuclear structure corrections based on experimental data that suffer from very large uncertainties. We present the first steps towards an ab initio computation of these quantities using few-body techniques.
Exploring three-nucleon forces via three- and four-nucleon scattering

Kimiko Sekiguchi

SciPost Phys. Proc. 3, 029 (2020) · published 26 February 2020 | · pdf

Three-nucleon force effects in three- and four-nucleon scattering are discussed from an experimental point of view.
The Hoyle Family: break-up measurements to probe α-condensation in light nuclei

Robin Smith, Jack Bishop, Joel Hirst, Tzany Kokalova, Carl Wheldon

SciPost Phys. Proc. 3, 030 (2020) · published 26 February 2020 | · pdf

The 12C Hoyle state is a candidate for α-condensation, due to its large volume and α-cluster structure. This paper discusses precision break-up measurements and how they can elucidate α-condensate structures. Two experiments are discussed in detail, firstly concerning the break-up of 12C and then the decays of heavier nuclei. With more theoretical input, and increasingly complex detector setups, precision break-up measurements can, in principle, provide insight into the structures of states in α-conjugate nuclei. At present, such searches have not delivered evidence for α-condensation in 12C or 16O.
Response functions and cross sections for inclusive neutrino scattering off $^2$H, $^3$H and $^3$He

Alessandro Grassi, Jacek Golak, Roman Skibiński, Kacper Topolnicki, Henryk Witała, Hiroyuki Kamada, Laura Elisa Marcucci

SciPost Phys. Proc. 3, 031 (2020) · published 26 February 2020 | · pdf

For several decades there has been an interest in studying neutrino scattering on light nuclei, with the hope of increasing knowledge about the theory of weak interactions and electroweak unification. A study of several neutrino induced reactions on light nuclei ($^2$H, $^3$H and $^3$He) is presented here. The cross section for these reactions is evaluated using the nuclear response functions, which holds the information about the nuclear interactions and structure. This approach has been tested for break-up reactions on the deuteron before and is now extended to three-nucleon break-up reactions.
Application of the JISP16 potential to the nucleon induced deuteron breakup process at E=13 MeV and E=65 MeV

Volodymyr Soloviov1, Jacek Golak, Roman Skibiński, Kacper Topolnicki, and Henryk Witała

SciPost Phys. Proc. 3, 032 (2020) · published 26 February 2020 | · pdf

The JISP16 nucleon-nucleon potential has been applied to investigations of the nucleon induced deuteron breakup reaction at the incoming nucleon laboratory energies E = 13 MeV and E = 65 MeV. We have found that for the studied process the JISP16 force gives a description of the exclusive cross section, which is generally similar to the ones obtained with the standard realistic nucleon-nucleon AV18 interaction. However, there are some regions of the phase space where the differential cross sections predicted by the JISP16 and AV18 models, differ by more than 100 %. These special kinematical configurations may possibly be useful to refit the JISP16 force parameters.
Few-body reactions investigated with the Trojan Horse Method

Roberta Spartà, Giuseppe G. Rapisarda, Claudio Spitaleri, M. La Cognata, Rosario G. Pizzone, S. Romano, Aurora Tumino

SciPost Phys. Proc. 3, 033 (2020) · published 26 February 2020 | · pdf

The Trojan Horse Method is an indirect method to measure reaction cross sections at energies of interest for nuclear astrophysics, exploiting the nuclei clustering properties. Here it is presented with its general features and detailed for the case of the 2H(d,p)3H and 2H(d,n)3He measurements, where interesting results for astrophysics and energy fusion power plants have been obtained.
Beryllium-9 in cluster effective field theory

Elena Filandri, Paolo Andreatta, Carlo A. Manzata, Chen Ji, W. Leidemann, G. Orlandini

SciPost Phys. Proc. 3, 034 (2020) · published 26 February 2020 | · pdf

We study the 9 Be ground-state energy with non-local αn and αα potentials derived from Cluster Effective Field Theory. The short-distance dependence of the interaction is regulated with a momentum cutoff. The potential parameters are fitted to reproduce scattering length and effective range. We implement such potential models in a Non-Symmetrized Hyperspherical Harmonics (NSHH) code in momentum space. In addition we calculate ground-state energies of various alpha nuclei. Work is in progress in view of the calculation of the photodisintegration of 9 Be with the Lorentz Integral Transform (LIT) method.
How to determine the shape of nuclear molecules with polarized gamma-rays

Lorenzo Fortunato

SciPost Phys. Proc. 3, 035 (2020) · published 26 February 2020 | · pdf

A method has been recently proposed to establish the geometry of the alpha-cluster arrangement in $^{12}$C making use of polarized gamma-rays. The ratio of intensities of scattered radiation at 90 degrees along and perpendicular to the initial direction of the electric field vector, called depolarization ratio, is a key quantity that allows to underpin the nature of totally symmetric modes of vibrations. This allows to connect with the underlying point-group structure and therefore to the geometric shape of the nuclear molecule. This method is reviewed for $^{12}$C and extended to other configurations, such as three unequal clusters and four identical clusters (e.g. $^{16}$O).
Description of continuum structures in a discrete basis: Three-body resonances and two-nucleon decays

Jesús Casal, Manuela Rodríguez-Gallardo, José M. Arias, Joaquín Gómez-Camacho, Lorenzo Fortunato, Andrea Vitturi

SciPost Phys. Proc. 3, 036 (2020) · published 26 February 2020 | · pdf

Weakly bound and unbound three-body nuclei are studied by using the pseudostate method within the hyperspherical formalism. After introducing the theoretical framework, the method is applied first to the $\boldsymbol{^9}$Be nucleus, showing a good agreement with the available data for its low-lying dipole response. Then, recent results on the structure and decay of the two-neutron emitters $\boldsymbol{^{26}}$O and $\boldsymbol{^{16}}$Be are presented. In particular, the role of the $\boldsymbol{n}$-$\boldsymbol{n}$ correlation in shaping their properties is discussed.
The inversion of the Lorentz integral transform with controlled resolution

Winfried Leidemann, Victor D. Efros, Veronica Yu. Shalamova

SciPost Phys. Proc. 3, 037 (2020) · published 26 February 2020 | · pdf

The Lorentz integral transform (LIT) method is briefly presented. The ill-posedness of the inversion is discussed and it is pointed out that the LIT is an integral transform with a controlled resolution. As application the dipole response of a three-particle system bound in a hypercentral potential is considered. The inversion is performed in two ways, both employ expansions of the response function and of the LIT on a basis set and a transformed basis set, respectively. A previous study of the process under consideration seemed to point to serious problems in the inversion process. In the present work, however, it is shown that the LIT approach can be carried out in a reliable way.
Properties of heavy mesons at finite temperature

Gloria Montaña, Angels Ramos, Laura Tolós

SciPost Phys. Proc. 3, 038 (2020) · published 26 February 2020 | · pdf

We study the properties of heavy mesons using a unitarized approach in a hot pionic medium, based on an effective hadronic theory. The interaction between the heavy mesons and pseudoscalar Goldstone bosons is described by a chiral Lagrangian at next-to-leading order in the chiral expansion and leading order in the heavy-quark mass expansion so as to satisfy heavy-quark spin symmetry. The meson-meson scattering problem in coupled channels with finite-temperature corrections is solved in a self-consistent manner. Our results show that the masses of the ground-state charmed mesons $D(0^-)$ and $D_s(1^-)$ decrease in a pionic environment at $T\neq 0$ and they acquire a substantial width. As a consequence, the behaviour of excited mesonic states (i.e. $D_{s0}^*(2317)^\pm$ and $D_0^*(2300)^{0,\pm}$), generated dynamically in our heavy-light molecular model, is also modified at $T\neq 0$. The aim is to test our results against Lattice QCD calculations in the future.
Kaonic atoms experiment at the DAΦNE collider by SIDDHARTA/SIDDHARTA-2

M. Skurzok, A. Amirkhani, A. Baniahmad, M. Bazzi, D. Bosnar, M. Bragadireanu, M. Carminati, M. Cargnelli, A. Clozza, C. Curceanu, L. De Paolis, R. Del Grande, L. Fabbietti, C. Fiorini, C. Guaraldo, M. Iliescu, M. Iwasaki, P. Levi Sandri, J. Marton, M. Miliucci, P. Moskal, S. Niedzwiecki, S. Okada, D. Pietreanu, K. Piscicchia, A. Scordo, M. Silarski, D. Sirghi, F. Sirghi, A. Spallone, M. Tüchler, O. Vazquez Doce, E. Widmann, J. Zmeskal

SciPost Phys. Proc. 3, 039 (2020) · published 26 February 2020 | · pdf

The excellent quality kaon beam provided by the DAΦNE collider of LNF-INFN (Italy) together with SIDDHARTA/SIDDHARTA-2 new experimental techniques, as very precise and fast-response X-ray detectors, allow to perform unprecedented measurements on light kaonic atoms crucial for a deeper understanding of the low-energy quantum chromodynamics (QCD) in the strangeness sector. In this paper an overview of the main results obtained by the SIDDHARTA collaboration, as well as the future plans related to the SIDDHARTA-2 experiment, are discussed.
Effect of isospin averaging for $ppK^-$ kaonic cluster

Branislav Vlahovic, Igor Filikhin

SciPost Phys. Proc. 3, 040 (2020) · published 27 February 2020 | · pdf

The kaonic cluster $ppK^-$ is described by isospin-dependent $N{\bar K}$ potentials with significant difference between singlet and triplet components. The quasi-bound state energy of the system is calculated based on the configuration space Faddeev equations within isospin and averaged potential models. The isospin averaging of $ N{\bar K} $ potentials is used to simplify the isospin model to isospinless one. We show that three-body bound state energy $E_{3}$ has a lower bound within the isospin formalism due to relation $\left\vert E_{3}(V_{NN}=0)\right\vert<2\left\vert E_{2}\right\vert$, where $E_{2}$ is the binding energy of isospin singlet state of the $N{\bar K}$ subsystem. The averaged potential model demonstrates opposite relation between $|E_{2}|$ and $|E_{3}(V_{NN}=0)|$.
Four-body Faddeev-type calculation of the $\bar{K}NNN$ system: Preliminary results

Nina V. Shevchenko

SciPost Phys. Proc. 3, 041 (2020) · published 27 February 2020 | · pdf

The paper is devoted to the $\bar{K}NNN$ system, consisting of an antikaon and three nucleons. Four-body Faddeev-type AGS equations are being solved in order to find possible quasi-bound state in the system.
An accurate allowance for initial and final state interactions in the treatment of the alpha-alpha Bremsstrahlung

Adam M. Arslanaliev, Aleksandr V. Shebeko

SciPost Phys. Proc. 3, 042 (2020) · published 27 February 2020 | · pdf

The alpha-alpha bremsstrahlung is studied using the generalization of the Siegert theorem. The corresponding amplitude is written in the gauge invariant form. Special attention is paid to taking into account the Coulomb interaction. Some correlation function is found and its dependence on the strong interaction is discussed.
Calculation of asymptotic normalization coefficients in the complex-ranged Gaussian basis

Dinmukhamed A. Sailaubek, Olga A. Rubtsova

SciPost Phys. Proc. 3, 043 (2020) · published 27 February 2020 | · pdf

A new technique towards finding asymptotic normalization coefficients in the complex-ranged Gaussian basis is presented. It is shown that a diagonalisation procedure for the total Hamiltonian matrix in the given basis results in approximation for a radial part of the bound state wave function from the origin up to the far asymptotic distances, which allows to extract ANCs rather accurately. The method is illustrated by calculations of single-particle ANCs for nuclei bound states in cases of non-local nucleon-nucleus interactions, in particular, phenomenological global potentials with the Perey-Buck's non-locality.
Particle representation for $NN{\bar K}$ system

Branislav Vlahovic, Igor Filikhin, Roman Ya. Kezarashvili

SciPost Phys. Proc. 3, 044 (2020) · published 27 February 2020 | · pdf

In the framework of the Faddeev equations in configuration space we perform an analysis of quasi-bound state of the $NN{\bar K}$ system within a particle model. In our approach, the system $NN{\bar K}(s_{NN}=0)$ ($NN{\bar K}(s_{NN}=1))$ is described as a superposition of $ppK^{-}$ and $pn{\bar K}^0$ ($nn{\bar K}^{0}$ and $pn{ K}^-$) states, which is possible due to a particle transition. The relation of the particle model to the theory of a two-state quantum system is addressed and discussed taking into account the possibilities of deep and shallow $NN{\bar K}(s_{NN}=0)$ quasi-bound states.
QED in the clothed-particle representation: a fresh look at positronium properties treatment

Yan A. Kostylenko, Adam M. Arslanaliev, Aleksandr V. Shebeko

SciPost Phys. Proc. 3, 045 (2020) · published 27 February 2020 | · pdf

We have extended our previous applications of the method of unitary clothing transformations (UCTs) in mesodynamics [1, 2] to quantum electrodynamics (QED) [3, 4]. An analytical expression for the QED Hamiltonian in the clothed-particle representation (CPR) has been derived. Its distinctive feature is the appearance of a new family of the Hermitian and energy independent interaction operators built up in the e^2-order for the clothed electrons and positrons instead the primary canonical interaction between electromagnetic and electron-positron fields. The problem of describing the bound states in QED in case of the positronium system has been considered. The first correction to the energy of the ground state of the para-positronium and its decay rate to two photons has been calculated by using the new interaction operators.
Three-nucleon force effects in the FSI configuration of the d(n, nn)p breakup reaction

Hiroyuki Kamada, Henryk Witała, Jacek Golak, Roman Skibiński

SciPost Phys. Proc. 3, 046 (2020) · published 27 February 2020 | · pdf

We investigated three-nucleon (3N) force effects in the final state interaction (FSI) configuration of the d(n, nn)p breakup reaction at the incoming nucleon energy E n = 200 MeV. Although 3N force effects for the elastic nucleon-deuteron scattering cross section at comparable energies are located predominantly in the region of intermediate and backward angles, the corresponding 3N force effects for the integrated FSI configuration breakup cross section are found also at forward scattering angles.
A time-dependent Hartree-Fock study of triple-alpha dynamics

Paul D. Stevenson, J. L. Willerton

SciPost Phys. Proc. 3, 047 (2020) · published 27 February 2020 | · pdf

Time-dependent Hartree-Fock calculations have been performed for fusion reactions of He-4 + He-4 -> Be*-8, followed by He-4 + Be*-8 . Depending on the orientation of the initial state, a linear chain vibrational state or a triangular vibration is found in 12C, with transitions between these states observed. The vibrations of the linear chain state and the triangular state occur at ~9 and 4 MeV respectively.
Study of light nuclei by polarization observables in electron scattering

Simon Širca

SciPost Phys. Proc. 3, 048 (2020) · published 27 February 2020 | · pdf

Electron-induced proton, neutron and deuteron knock-out remains the most versatile probe of the electro-magnetic properties and spin structure of light nuclei. The advent of highly polarized beams and targets and improvements in recoil polarization methods, as well as analysis and simulation techniques, have enabled us to study the static and dynamical properties of few-body systems with unprecedented precision. Recent experiments at Jefferson Lab and MAMI are presented and put into perspective of state-of-the art Faddeev calculations, with focus on the $^\mathbf{3}\mathbf{He}$ nucleus.
Virial expansion coefficients in the unitary Fermi gas

Shimpei Endo

SciPost Phys. Proc. 3, 049 (2020) · published 27 February 2020 | · pdf

Virial expansion is widely used in cold atoms to analyze high temperature strongly correlated many-body systems. As the n-th order virial expansion coefficient can be accurately obtained by exactly solving up to n-body problems, the virial expansion offers a few-body approach to study strongly correlated many-body problems. In particular, the virial expansion has successfully been applied to unitary Fermi gas. We review recent progress of the virial expansion studies in the unitary Fermi gas, in particular the fourth order virial coefficient.
An investigation of the appearance of a long range nuclear potential in ultra low energy nuclear synthesis

Shinsho Oryu, Takashi Watanabe, Yasuhisa Hiratsuka, Masayuki Takeda

SciPost Phys. Proc. 3, 050 (2020) · published 27 February 2020 | · pdf

A new potential, the $general$ $particle$ $transfer$ $potential$: so called ``GPT'' potential was represented in the previous paper which indicates a Yukawa-type potential for shorter range, but a $1/r^n$-type potential for longer range where $n=2$ includes the Efimov-like potential in the hadron system. In order to confirm the existence of a GPT potential, we investigate the possibility of Cs+2d$\rightarrow$La reaction on the three-ion quasi-molecule CsD$_2$ which is covered by twelve Pd or a CsD$_2$Pd$_{12}$-cluster, where the three-body bound states and wave functions for D-Cs-D molecular and d-Cs-d nuclear systems are calculated. We obtain an approximate E2-transition from the molecular states to the nuclear states. The transition ratio between the short range nuclear potential with the $1/r^2$-type long range potential and without long range potential is $W_{i\rightarrow f}^{E2';L}/W_{i\rightarrow f}^{E2';S}\approx 10^8$. If the reaction Cs+2D$\rightarrow$La is experimentally observed, then the existence of the GPT potential could be confirmed.
Three-body correlations in mesonic-atom-like systems

Hajime Moriya, Wataru Horiuchi, Jean-Marc Richard

SciPost Phys. Proc. 3, 051 (2020) · published 27 February 2020 | · pdf

Three-body correlations in three-body exotic atoms are studied with simple models that consist of three bosons interacting through a superposition of long- and short-range potentials. We discuss the correlations among particles by comparing the energy shifts given by precise three-body calculations and by the Deser-Trueman formula, in which the long- and short-range contributions are factorized. By varying the coupling of the short-range potential, we evaluate the ranges of the strength where the two-body correlations dominate and where the three-body correlations cannot be neglected.
Lattice phase shifts and mixing angles for an arbitrary number of coupled channels

Lukas Bovermann, Evgeny Epelbaum, Hermann Krebs, Dean Lee

SciPost Phys. Proc. 3, 052 (2020) · published 27 February 2020 | · pdf

We present a lattice method for determining scattering phase shifts and mixing angles for the case of an arbitrary number of coupled channels. The proposed method combines a spherical wall boundary condition and a channel-mixing auxiliary potential to extract the full-rank S-matrix from the radial wave functions. We consider the scattering problem of two spin-1 bosons interacting with a test potential involving up to four coupled channels. For this benchmark system, the phase shifts and mixing angles are shown to agree on the lattice and in the continuum. Our method should allow to extend previous two-channel nuclear lattice EFT simulations to mixing of more than two partial waves.
Study of deuteron-proton backward elastic scattering at intermediate energies

Nadezhda Ladygina

SciPost Phys. Proc. 3, 053 (2020) · published 27 February 2020 | · pdf

We study deuteron- proton elastic scattering in the deuteron energy range between 500 MeV and 2~GeV at the cms scattering angle $\theta^*\ge 140^\circ$. The reaction is considered in the relativistic multiple scattering expansion framework. The four reaction mechanisms are included into consideration: one-nucleon exchange, single scattering, double scattering, and the term corresponding to the delta excitation in the intermediate state. The model is applied to describe the angular dependence of the differential cross section at the deuteron energies of between 880 and 1300 MeV. Also the energy dependence of the differential cross section and polarisation observables such as tensor analyzing power $T_{20}$ and polarization transfer from the deuteron to proton $\varkappa$ are considered at the scattering angle equal to 180$^\circ$. Contributions of the different reaction mechanisms into the reaction amplitude are demonstrated in comparison with the existing experimental data.
Three-nucleon force effects in nucleon-deuteron scattering at backward angles

Souichi Ishikawa

SciPost Phys. Proc. 3, 054 (2020) · published 27 February 2020 | · pdf

Elastic and breakup cross sections in nucleon-deuteron scattering at intermediate energies are calculated using a realistic two-nucleon potential and three-nucleon potentials based on the exchange of two pions among three nucleons. Attractive effects of the pion-exchange at medium range region in the three-nucleon potential are recovered by using a shorter range cutoff. It is shown that these effects increase the cross sections at backward angles, which tends to reduce discrepancies between theoretical calculations and experimental data.
Correlations among 3N observables

Yuriy Volkotrub, Jacek Golak, Roman Skibiński, Kacper Topolnicki, Henryk Witała

SciPost Phys. Proc. 3, 055 (2020) · published 27 February 2020 | · pdf

We use a correlation matrix of two-nucleon (2N) potential parameters to investigate correlations among three-nucleon (3N) observables for the elastic nucleon-deuteron (Nd) scattering process. We employ the up-to-date 2N semilocal momentum-space regularized chiral interactions and the phenomenological OPE-Gaussian potential and using the Faddeev formalism we calculate 3N observables and their correlations. As an example, we present the correlation between the differential cross section and the deuteron analyzing power T20.
The $D_{03}(2380)$ dibaryon resonance excitation in the $pd\to pd\pi\pi$ reaction.

Nurbek Tursunbayev, Yuriy Uzikov

SciPost Phys. Proc. 3, 056 (2020) · published 27 February 2020 | · pdf

The recent ANKE@COSY data on the differential cross section of reaction $pd \to pd\pi\pi$ demonstrate a peak at invariant mass of the final $d\pi\pi$ system $2.38~GeV$, that corresponds to the isocalar $J^P = 3^+$ dibaryon $D_{03}$, and also enhancement in the distribution over the invariant mass of two final pions. The two-resonance model involving the $t$-channel $\sigma$-meson exchange between the proton and deuteron in the subprocess $pd\to pD_{03}$ and the sequential decays $D_{03}\to D_{12}+\pi$ and $D_{12}\to d +\pi$ was applied to describe the shapes of these distributions with the lowest orbital angular momenta in the corresponding vertices. A possible role of higher orbital momenta in those vertices is studied here.
Quasi-free limit in the deuteron-deuteron three-body break-up process

R. Ramazani-Sharifabadi, H. R. Amir-Ahmadi, M. T. Bayat, I. Ciepał, M. Eslami-Kalantari, N. Kalantar-Nayestanaki, St. Kistryn, A. Kozela, M. Mahjour-Shafiei, H. Mardanpour, J. G. Messchendorp, M. Mohammadi-Dadkan, A. Ramazani-Moghaddam-Arani, E. Stephan, and H. Tavakoli-Zaniani

SciPost Phys. Proc. 3, 057 (2020) · published 1 April 2020 | · pdf

Detailed measurements of vector and tensor analyzing powers of the 2H(d, dp)n breakup process are presented. The data were obtained using a polarized deuteron-beam with an energy of 65 MeV/nucleon impinging on a liquid-deuterium target. The experiment was conducted at the AGOR facility at KVI using the BINA 4Pi-detection system. The focus of this contribution is to analyze data of the dd scattering process in the regime at which the neutron acts as a spectator, which we refer to as the quasi-free (QF) limit. To achieve this, events for which the final-state deuteron and proton are coplanar have been analyzed and the data have been sorted for various reconstructed momenta of the missing neutron. In the limit of vanishing neutron momentum and at small deuteron-proton momentum transfer, the data match very well with measured and predicted spin observables of the elastic deuteron-proton scattering process. The agreement deteriorates rapidly with increasing neutron momentum and deuteron-proton momentum transfer. The results of coplanar configurations in four-body phase space are compared with the results of recent available theoretical calculations based on the Single-Scattering Approximation.