Hyperfine splitting effects in string hadronization

Abstract We revisit the recipe for hadron formation in the Lund string hadronization model. Given an incoming quark or quark-diquark pair, weights for hadron formation are updated to take hyperfine splitting effects arising from the mass difference between $$\mathrm {u,d}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>u</mml:mi> <mml:mo>,</mml:mo> <mml:mi>d</mml:mi> </mml:mrow> </mml:math> -type and $$\mathrm {s}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>s</mml:mi> </mml:math> -type quarks. We find that the procedure improves the description of hadron yields in $$\mathrm {e}^+\mathrm {e}^-$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> <mml:mo>+</mml:mo> </mml:msup> <mml:msup> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> <mml:mo>-</mml:mo> </mml:msup> </mml:mrow> </mml:math> collisions and the $$\phi $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>ϕ</mml:mi> </mml:math> cross section in neutral current DIS. We also show results for proton collisions, and discuss the future use of this study in the context of small system collectivity.