Faddeev Medal 2018

Vitaly Efimov and Rudolf Grimm Win Faddeev Medal

The international panel of experts, chaired by G. Orlandini (Trento), has selected the winners of the 2018 Faddeev Medal award. They are:

Vitaly Efimov: "For the theoretical discovery of a series of weakly-bound three-body quantum states known as Efimov states."
Rudolf Grimm: "In recognition of his ground-breaking experiments confirming the Efimov effect."

The award cerimony will take place in Caen, France, during the 22nd International Conference on Few-body Problems in Physics . For more details on FB22, please see the conference website.

The Faddeev medal was inaugurated in 2016 by the European Research Committee on Few-Body Problems in Physics (ERCFBP) and the Topical Group on Few-Body Systems & Multiparticle Dynamics (GFB) of the American Physical Society to recognize distinguished achievement in Few-Body Physics. It is named in honor of our distinguished colleague Ludwig Faddeev. The medal is awarded every three years to a scientist (or scientists) who advanced the field of few-body physics significantly—either through ground-breaking research or due to crucial progress achieved over the course of a career.

Vitaly N. Efimov is a Russian theoretical physicist. He proposed the existence of a novel and exotic state of matter now dubbed the Efimov State as a researcher in A. F. Ioffe Physico-Technical Institute, USSR Academy of Sciences, Leningrad, USSR in his 1970 paper "Energy levels arising from resonant two-body forces in a three-body system". He is now an affiliate professor of physics at the University of Washington.

Rudolf Grimm is an Austrian experimental physicist. His work focused on Bose–Einstein condensation of atoms and molecules and on fermionic quantum gases. In 2002 his working group succeeded for the first time ever to produce a Bose–Einstein condensate from caesium atoms. In 2006, his working group also succeeded in the first experimental observation of Efimov states. Since year 2000 he is a staff scientist of University of Innsbruck and since 2006 Director of the Research Center for Quantum Physics.

Abstract

This paper reviews our work on the measurements of absolute production cross sections of $\gamma $ -rays from the (p,p $^{\prime }\gamma $ ) reactions on $^{12}$ C and $^{16}$ O. The measurements cover a range of 8–16 MeV for the incident proton beam. The angular distributions of the $\gamma $ -rays have been measured. A detailed phenomenological analysis within the framework of optical model formalism has been carried out to reproduce the experimental data. The existing global set of elastic, polarization and total reaction data for protons and neutrons have been used to generate the optical model potential. The nuclear structure effects have been included in the calculations by considering the roles of coupling of the low-lying states, the presence of resonances and nuclear deformations. The potentials so generated have been used to calculate the differential and total cross sections for both (p,p $^\prime $ ) and (p,p $^\prime \gamma $ ) reactions. The results of the analysis are in good agreement with the measured data for the observed $\gamma $ -rays. However, discrepancies still exist in reproducing the finer details of the cross sections. The existing discrepancies between our phenomenological analysis and the experimental data demonstrate the rather complex roles of channel couplings, resonances in the compound nuclear system and target deformation. The significant contribution of nuclear structure effects in light mass nucleus like $^{12}$ C and $^{16}$ O, leads to an apparent loss of predictive power of the theoretical calculation for low-energy region (less than 10 MeV) of the projectile energy.

Test of the Charge Symmetry Hypothesis of NN Interaction from the Coulomb-Free p–p Scattering Cross Section and Its Relation to Universality

Abstract

We examine the results on the determination of the Coulomb-free ¹ $S_0$ proton–proton (p–p) scattering length by analyzing the cross section of the quasi-free p + d $\rightarrow $ p + p + n reaction at center-of-mass energies below 1 MeV. This was achieved using a Bayesian data-fitting approach, yielding a p–p scattering length $a_{pp} = -18.17^{+0.52}_{-0.58}|_{stat}\pm 0.01_{syst}$ fm and effective range $r_0 = 2.80\pm 0.05_{stat}\pm 0.001_{syst}$ fm. We test the stability of the results against the upper energy cutoff and fitting data sets separately. A model based on the Eckart potential is introduced for an effective description in the universal window. In this model, the short-range interaction is considered as a whole, similar to how the s-wave phase-shift $\delta $ functions in describing low-energy nucleon–nucleon scattering data. Based on our analysis, we confirm that the obtained parameters accurately represent the characteristics of the short-range physics and the influence of the up-down quark mass difference on the charge symmetry breaking is less significant as initially anticipated. Additionally, we suggest evaluating the charge symmetry breaking of the short-range interaction rather than solely focusing on the nuclear interaction.

Isospin Symmetry of $$\omega $$ Meson at Finite Temperature in the Soft-Wall Model of Holographic QCD

Abstract

The coupling constants of $\rho $ meson-nucleon and $\omega $ meson-nucleon are connected through the isospin relation. Using the soft-wall model of holographic QCD, the current work aims to examine the violation (if any) of isospin symmetry of the $\omega $ -meson as well as the temperature dependency of the $\omega $ -meson- $\Delta $ and $\omega $ -meson-nucleon- $\Delta $ baryon coupling constants. Applying the temperature-dependent profile functions of the vector and fermion fields to the expression of the coupling constants in the model yields the temperature dependence of the coupling constants. The minimum and magnetic type interactions between vector and fermion fields in 5-dimensional AdS space-time are included in the written interaction Lagrangian terms. The temperature dependence of the coupling constants $g_{\omega N N}(T)$ , $g_{\omega \Delta \Delta }(T)$ , and $g_{\omega N \Delta }(T)$ has been investigated. Comparing $g_{\omega NN}(T)$ with the coupling constant $g_{\rho NN}(T)$ , it is found that the isospin symmetry of the $\omega $ and $\rho $ mesons is not violated at the finite temperature. It is also observed that the coupling constant of the $\omega $ meson with baryons decreases as the temperature increases, and this coupling constant becomes zero near the confinement-deconfinement phase transition temperature.

From atoms to nuclei, quarks and bejond...

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