Exploring Few-body Universality of a Putative Halo-bound D0-meson-neutron-neutron System via Faddeev Equations

Abstract
We present a demonstration of remnant structural universality in a putative S-wave 2n-halo-bound D0nn system in the total spin J=0 and isospin T=3/2 channel by invoking a zero coupling limit (ZCL) idealization eliminating sub-threshold decay channels. In particular, we estimate the one- and two-body matter density form factors along with the associated (root) mean-square radii and the n-D0-n opening angle. For this purpose, we carry out a leading-order investigation in the context of an effective quantum mechanical Faddeev approach in the momentum representation. Using Jacobi momentum representation, we build a complete set of partial wave projected bases to reconstruct the full three-body D0nn wave functions in terms of distinct sub-system re-arrangement channels. By projecting onto the chosen basis, a set of coupled Faddeev integral equations is derived that describe the re-scattering dynamics of the coupled spin and isospin sub-systems. Furthermore, by introducing short-distance two-body separable interactions, along with the scattering amplitudes (T-matrices) expressed via the so-called {\it spectator functions}, we establish a one-to-one correspondence with the well-known Skornyakov-Ter-Martirosyan integral equations used in the context of halo-EFT at leading order. A study of the regulator dependence of the integral equations reveals the underlying Efimovian character of three-body observables; in particular, those of the ground state are quite sensitive to the regulator variations. Nevertheless, with the integral equations and three-body wave functions modified by the three-body force, such regulator dependence gets asymptotically suppressed in agreement with the renormalization group invariance. It is thereby concluded that for a sufficiently small magnitude of the ground-state three-body binding energy, the D0nn system in ZCL assumes a halo-bound universal structure.

About the Speaker
Udit Raha is currently an associate professor in the Department of Physics at the Indian Institute of Technology Guwahati in India since 2012. He obtained his Ph.D.  in theoretical hadron physics from the University of Bonn in Germany in 2006. Subsequently, he had post doctoral research experiences at University of Basel in Switzerland (2006-2008), National Taiwan University in Taiwan (2008-2010), and University of South Carolina, Columbia in USA (2010-2012). His research interests Include formulation of low-energy effective field theories of strong interaction applied to hadronic and nuclear few-body systems.