2026/01/05 by BESIII Collaboration, M. N. Achasov, M. Ablikim +735
Engineering · Physics and Astronomy · #Cross section (physics) #Deformation (meteorology) #Focus (optics) #Measure (data warehouse) #Particle Accelerators and Free-Electron Lasers #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #Section (typography)
paper · pdf · open access · doi:10.1103/98g1-t98b
published in Physical review. D/Physical review. D. 113(11) (American Physical Society)
openalex publication_date 2026/03/17 · openalex created_date 2026/03/18 · openalex updated_date 2026/08/01
Using data samples with a total integrated luminosity of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:mn>22.1</a:mn> <a:mtext> </a:mtext> <a:mtext> </a:mtext> <a:msup> <a:mrow> <a:mi>fb</a:mi> </a:mrow> <a:mrow> <a:mo>−</a:mo> <a:mn>1</a:mn> </a:mrow> </a:msup> </a:mrow> </a:math> at center-of-mass energies between 4.008 and 4.951 GeV collected with the BESIII detector, the cross sections of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:msup> <c:mi>e</c:mi> <c:mo>+</c:mo> </c:msup> <c:msup> <c:mi>e</c:mi> <c:mo>−</c:mo> </c:msup> <c:mo stretchy="false">→</c:mo> <c:msup> <c:mi>π</c:mi> <c:mn>0</c:mn> </c:msup> <c:msup> <c:mi>π</c:mi> <c:mn>0</c:mn> </c:msup> <c:mi>ψ</c:mi> <c:mo stretchy="false">(</c:mo> <c:mn>3686</c:mn> <c:mo stretchy="false">)</c:mo> </c:math> process are measured. The obtained cross sections are found to be approximately one-half of those of <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"> <h:msup> <h:mi>e</h:mi> <h:mo>+</h:mo> </h:msup> <h:msup> <h:mi>e</h:mi> <h:mo>−</h:mo> </h:msup> <h:mo stretchy="false">→</h:mo> <h:msup> <h:mi>π</h:mi> <h:mo>+</h:mo> </h:msup> <h:msup> <h:mi>π</h:mi> <h:mo>−</h:mo> </h:msup> <h:mi>ψ</h:mi> <h:mo stretchy="false">(</h:mo> <h:mn>3686</h:mn> <h:mo stretchy="false">)</h:mo> </h:math> , consistent with the isospin symmetry expectation. A coherent fit to the dressed cross sections is performed, with the <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:mi>Y</m:mi> <m:mo stretchy="false">(</m:mo> <m:mn>4230</m:mn> <m:mo stretchy="false">)</m:mo> </m:math> parameters fixed at the values measured in <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"> <q:msup> <q:mi>e</q:mi> <q:mo>+</q:mo> </q:msup> <q:msup> <q:mi>e</q:mi> <q:mo>−</q:mo> </q:msup> <q:mo stretchy="false">→</q:mo> <q:msup> <q:mi>π</q:mi> <q:mo>+</q:mo> </q:msup> <q:msup> <q:mi>π</q:mi> <q:mo>−</q:mo> </q:msup> <q:mi>ψ</q:mi> <q:mo stretchy="false">(</q:mo> <q:mn>3686</q:mn> <q:mo stretchy="false">)</q:mo> </q:math> . The significances of the <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"> <v:mi>Y</v:mi> <v:mo stretchy="false">(</v:mo> <v:mn>4390</v:mn> <v:mo stretchy="false">)</v:mo> </v:math> and <z:math xmlns:z="http://www.w3.org/1998/Math/MathML" display="inline"> <z:mi>Y</z:mi> <z:mo stretchy="false">(</z:mo> <z:mn>4660</z:mn> <z:mo stretchy="false">)</z:mo> </z:math> are both larger than <db:math xmlns:db="http://www.w3.org/1998/Math/MathML" display="inline"> <db:mn>5</db:mn> <db:mi>σ</db:mi> </db:math> , and their masses and widths are consistent with the previous measurement in the <fb:math xmlns:fb="http://www.w3.org/1998/Math/MathML" display="inline"> <fb:msup> <fb:mi>e</fb:mi> <fb:mo>+</fb:mo> </fb:msup> <fb:msup> <fb:mi>e</fb:mi> <fb:mo>−</fb:mo> </fb:msup> <fb:mo stretchy="false">→</fb:mo> <fb:msup> <fb:mi>π</fb:mi> <fb:mo>+</fb:mo> </fb:msup> <fb:msup> <fb:mi>π</fb:mi> <fb:mo>−</fb:mo> </fb:msup> <fb:mi>ψ</fb:mi> <fb:mo stretchy="false">(</fb:mo> <fb:mn>3686</fb:mn> <fb:mo stretchy="false">)</fb:mo> </fb:math> process.