2024/12/30 by Hui-Hua Zhong, Mingsheng Liu, Ming-Sheng Liu +6 · 5 citations
Physics and Astronomy · #Quantum Chromodynamics and Particle Interactions #Particle physics theoretical and experimental studies #High-Energy Particle Collisions Research
paper · doi:10.1103/physrevd.110.116034
In this work, we systematically study both the mass spectra and strong decays of the nucleon and <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi mathvariant="normal">Δ</a:mi> </a:math> resonances up to the <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"> <d:mi>N</d:mi> <d:mo>=</d:mo> <d:mn>2</d:mn> </d:math> shell within a unified quark model framework with chiral dynamics. In this framework we achieve a good description of the strong decay properties of the well-established nucleon and <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"> <f:mi mathvariant="normal">Δ</f:mi> </f:math> resonances. Meanwhile, the mass reversal between <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"> <i:mi>N</i:mi> <i:mo stretchy="false">(</i:mo> <i:mn>1440</i:mn> <i:mo stretchy="false">)</i:mo> <i:mn>1</i:mn> <i:mo>/</i:mo> <i:msup> <i:mn>2</i:mn> <i:mo>+</i:mo> </i:msup> </i:math> as the first radial excitation state and the <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:mn>1</m:mn> <m:mi>P</m:mi> </m:math> -wave nucleon resonances can be explained. We show that the three-body spin-orbit potential arising from the one-gluon exchange can cause a large configuration mixing between <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"> <o:mi>N</o:mi> <o:mo stretchy="false">(</o:mo> <o:mn>1520</o:mn> <o:mo stretchy="false">)</o:mo> <o:mn>3</o:mn> <o:mo>/</o:mo> <o:msup> <o:mn>2</o:mn> <o:mo>−</o:mo> </o:msup> </o:math> and <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"> <s:mi>N</s:mi> <s:mo stretchy="false">(</s:mo> <s:mn>1700</s:mn> <s:mo stretchy="false">)</s:mo> <s:mn>3</s:mn> <s:mo>/</s:mo> <s:msup> <s:mn>2</s:mn> <s:mo>−</s:mo> </s:msup> </s:math> and is also responsible for the large splitting between <w:math xmlns:w="http://www.w3.org/1998/Math/MathML" display="inline"> <w:mi mathvariant="normal">Δ</w:mi> <w:mo stretchy="false">(</w:mo> <w:mn>1600</w:mn> <w:mo stretchy="false">)</w:mo> <w:mn>1</w:mn> <w:mo>/</w:mo> <w:msup> <w:mn>2</w:mn> <w:mo>−</w:mo> </w:msup> </w:math> and <bb:math xmlns:bb="http://www.w3.org/1998/Math/MathML" display="inline"> <bb:mi mathvariant="normal">Δ</bb:mi> <bb:mo stretchy="false">(</bb:mo> <bb:mn>1700</bb:mn> <bb:mo stretchy="false">)</bb:mo> <bb:mn>3</bb:mn> <bb:mo>/</bb:mo> <bb:msup> <bb:mn>2</bb:mn> <bb:mo>−</bb:mo> </bb:msup> </bb:math> . Some of these baryon resonances tend to weakly couple to the <gb:math xmlns:gb="http://www.w3.org/1998/Math/MathML" display="inline"> <gb:mi>N</gb:mi> <gb:mi>π</gb:mi> </gb:math> , <ib:math xmlns:ib="http://www.w3.org/1998/Math/MathML" display="inline"> <ib:mi>N</ib:mi> <ib:mi>η</ib:mi> </ib:math> , <kb:math xmlns:kb="http://www.w3.org/1998/Math/MathML" display="inline"> <kb:mi>K</kb:mi> <kb:mi mathvariant="normal">Λ</kb:mi> </kb:math> , and <nb:math xmlns:nb="http://www.w3.org/1998/Math/MathML" display="inline"> <nb:mi>K</nb:mi> <nb:mi mathvariant="normal">Σ</nb:mi> </nb:math> channels, which may answer the question of why they have not been established in these channels via the <qb:math xmlns:qb="http://www.w3.org/1998/Math/MathML" display="inline"> <qb:mi>π</qb:mi> <qb:mi>N</qb:mi> </qb:math> and <sb:math xmlns:sb="http://www.w3.org/1998/Math/MathML" display="inline"> <sb:mi>γ</sb:mi> <sb:mi>N</sb:mi> </sb:math> scatterings. It shows that these “missing resonances” may have large potentials to be established in the <ub:math xmlns:ub="http://www.w3.org/1998/Math/MathML" display="inline"> <ub:mi>N</ub:mi> <ub:mi>π</ub:mi> <ub:mi>π</ub:mi> </ub:math> final state due to their large decay rates into either the <wb:math xmlns:wb="http://www.w3.org/1998/Math/MathML" display="inline"> <wb:mi mathvariant="normal">Δ</wb:mi> <wb:mo stretchy="false">(</wb:mo> <wb:mn>1232</wb:mn> <wb:mo stretchy="false">)</wb:mo> </wb:math> or <bc:math xmlns:bc="http://www.w3.org/1998/Math/MathML" display="inline"> <bc:mn>1</bc:mn> <bc:mi>P</bc:mi> </bc:math> -wave nucleon resonances via the pionic decays. Further experimental search for their signals in charmonium decays at BESIII is thus strongly recommended. Published by the American Physical Society 2024