Transverse spin correlation of back-to-back dihadrons in unpolarized collisions

The spin correlation of back-to-back dihadrons emerges in unpolarized high-energy collision, empowering unpolarized experiments to shed light on the spin-dependent fragmentation functions. This work investigates the transverse spin correlation of back-to-back dihadrons in unpolarized <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msup><a:mrow><a:mi>e</a:mi></a:mrow><a:mrow><a:mo>+</a:mo></a:mrow></a:msup><a:msup><a:mrow><a:mi>e</a:mi></a:mrow><a:mrow><a:mo>−</a:mo></a:mrow></a:msup></a:mrow></a:math>, <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>p</c:mi><c:mi>p</c:mi></c:math>, and <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>γ</e:mi><e:mi>p</e:mi></e:math> collisions, which serves as a novel probe of the chiral-odd fragmentation function <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:msub><g:mi>H</g:mi><g:mrow><g:mn>1</g:mn><g:mi>T</g:mi></g:mrow></g:msub><g:mo stretchy="false">(</g:mo><g:mi>z</g:mi><g:mo stretchy="false">)</g:mo></g:math>. We compute the transverse spin correlation at the partonic level and establish a connection with helicity amplitudes. Measuring this observable in future experiments can reveal valuable information on the hadronization of transversely polarized quarks.