Comprehending heavy charmonia and their decays by hadron loop effects

TL;DR

This paper demonstrates that including hadron loop effects in models helps explain the spectrum and decays of heavy charmonium-like states by shifting pole positions and relating decay widths to complex energy plane poles.

Contribution

It introduces a method to incorporate hadron loop effects into charmonium spectrum analysis, explaining state shifts and decay properties more accurately than quenched models.

Findings

Pole positions are shifted from bare states due to hadron loop effects.

Open-charm decay widths are linked to the imaginary parts of pole positions.

X(3872) can be interpreted as a charmonium state dressed by hadron loops.

Abstract

We present that including the hadron loop effects could help us to understand the spectrum of the heavier charmonium-like states and their decays simultaneously. The observed states could be represented by the poles on the complex energy plane. By coupling to the opened thresholds, the pole positions are shifted from the bare states predicted in the quenched potential model to the complex energy plane. The pole masses are generally pulled down from the bare masses and the open-charm decay widths are related to the imaginary parts of the pole positions. Moreover, we also analyze the pole trajectory of the $\chi_{c1}(2P)$ state while the quark pair production rate from the vacuum changes in its uncertainty region, which indicates that the enigmatic X(3872) state may be regarded as a $1^{++}$ $c\bar{c}$ charmonium-dominated state dressed by the hadron loops as the others.