Model for baryon production in spin-dependent string fragmentation

We introduce spin- <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:mn>1</a:mn> <a:mo>/</a:mo> <a:mn>2</a:mn> </a:mrow> </a:math> baryons in the <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mrow> <c:mi>string</c:mi> <c:mo>+</c:mo> <c:mrow> <c:msub> <c:mrow> <c:mmultiscripts> <c:mrow> <c:mi>P</c:mi> </c:mrow> <c:mprescripts/> <c:none/> <c:mrow> <c:mn>3</c:mn> </c:mrow> </c:mmultiscripts> </c:mrow> <c:mrow> <c:mn>0</c:mn> </c:mrow> </c:msub> </c:mrow> </c:mrow> </c:math> model of hadronization, previously restricted to the production of pseudoscalar and vector mesons. Baryons are modeled as quark–diquark bound states, and baryon production is described by the tunneling of diquark–antidiquark pairs at string breaking points. Diquarks can be scalar or pseudovector, the latter being produced in the relative <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mrow> <e:msub> <e:mrow> <e:mmultiscripts> <e:mrow> <e:mi>D</e:mi> </e:mrow> <e:mprescripts/> <e:none/> <e:mrow> <e:mn>5</e:mn> </e:mrow> </e:mmultiscripts> </e:mrow> <e:mrow> <e:mn>0</e:mn> </e:mrow> </e:msub> </e:mrow> </e:math> state. Introducing the quark–baryon–diquark coupling, the relevant splitting amplitudes for the emission of baryons are constructed and used to explore analytically the model predictions. We find a Collins effect for baryon production in the fragmentations of transversely polarized quarks or diquarks as well as a baryon spontaneous <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:msub> <g:mi mathvariant="bold">p</g:mi> <g:mi mathvariant="normal">T</g:mi> </g:msub> </g:math> -dependent transverse polarization. The model is presented in a form suitable for implementation in a Monte Carlo event generator. The hadronic decays of polarized hyperons are also included.