2026/05/23 by H. Kamano, T. -S. H. Lee, T.-S. H. Lee
Physics and Astronomy · #Quantum Chromodynamics and Particle Interactions #Nuclear physics research studies #High-Energy Particle Collisions Research
paper · pdf · doi:10.1103/7ffl-qytm
We develop a novel model utilizing the forward <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:msup> <a:mi>K</a:mi> <a:mo>*</a:mo> </a:msup> </a:math> production reaction off the nucleon, <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:mrow> <b:mi>π</b:mi> <b:mi>N</b:mi> <b:mo>→</b:mo> <b:msup> <b:mi>K</b:mi> <b:mo>*</b:mo> </b:msup> <b:mi>M</b:mi> <b:mi>B</b:mi> </b:mrow> </b:math> , induced by a high-momentum <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mi>π</c:mi> </c:math> beam, as a tool to study low-lying <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:msup> <d:mi>Y</d:mi> <d:mo>*</d:mo> </d:msup> </d:math> resonances below and just above the <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:mrow> <e:mover accent="true"> <e:mi>K</e:mi> <e:mo>¯</e:mo> </e:mover> <e:mi>N</e:mi> </e:mrow> </e:math> threshold. Because conventional <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"> <g:mrow> <g:msup> <g:mi>K</g:mi> <g:mo>−</g:mo> </g:msup> <g:mi>p</g:mi> </g:mrow> </g:math> scattering experiments face difficulties in directly accessing this kinematic region, the proposed reaction offers a valuable complementary approach for <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"> <h:msup> <h:mi>Y</h:mi> <h:mo>*</h:mo> </h:msup> </h:math> spectroscopy. The constructed model is based on the one-meson exchange mechanism, which is known to dominate forward-angle production at high energies, and the half-off-shell scattering amplitudes from the ANL-Osaka dynamical coupled-channels models (Model A and Model B). We predict various observables, including differential cross sections and angular distributions. Our results demonstrate significant enhancements in the sub-threshold region of the invariant mass spectra. Notably, we show that overlapping resonances, such as a potential new <i:math xmlns:i="http://www.w3.org/1998/Math/MathML"> <i:mrow> <i:mn>3</i:mn> <i:mo>/</i:mo> <i:msup> <i:mn>2</i:mn> <i:mo>+</i:mo> </i:msup> </i:mrow> <i:mo> </i:mo> <i:mi mathvariant="normal">Σ</i:mi> </i:math> state and the well-established <k:math xmlns:k="http://www.w3.org/1998/Math/MathML"> <k:mrow> <k:mi mathvariant="normal">Σ</k:mi> <k:mrow> <k:mo>(</k:mo> <k:mn>1385</k:mn> <k:mo>)</k:mo> </k:mrow> <k:mn>3</k:mn> <k:mo>/</k:mo> <k:msup> <k:mn>2</k:mn> <k:mo>+</k:mo> </k:msup> </k:mrow> </k:math> , can constitute a single peak in the <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:mrow> <m:mi>π</m:mi> <m:mi mathvariant="normal">Λ</m:mi> </m:mrow> </m:math> mass spectrum, indicating that the existence of previously unconfirmed subthreshold states cannot be ruled out by analyzing only the existing mass spectrum data. Furthermore, we find that angular distributions provide strong discriminatory power to disentangle such overlapping states through partial-wave interference effects, while the <o:math xmlns:o="http://www.w3.org/1998/Math/MathML"> <o:msup> <o:mi>t</o:mi> <o:mo>′</o:mo> </o:msup> </o:math> and <p:math xmlns:p="http://www.w3.org/1998/Math/MathML"> <p:msubsup> <p:mi>ϕ</p:mi> <p:mi>M</p:mi> <p:mo>*</p:mo> </p:msubsup> </p:math> dependencies provide crucial constraints on the high-energy production mechanisms. Our predictions for these highly sensitive observables can facilitate high-statistics measurements, which are accessible at modern hadron facilities such as J-PARC, to unravel the <q:math xmlns:q="http://www.w3.org/1998/Math/MathML"> <q:mrow> <q:mi>S</q:mi> <q:mo>=</q:mo> <q:mo>−</q:mo> <q:mn>1</q:mn> </q:mrow> <q:mo> </q:mo> <q:msup> <q:mi>Y</q:mi> <q:mo>*</q:mo> </q:msup> </q:math> mass spectrum.