(\[eq:stringarea\])]{}, implies that $\kappa$ does not appear explicitly in this expression for the splitting function or the particle density.

In three dimensions the hadron mass $m$ in [eqs. (\[eq:Lund\])]{}, [(\[eq:split\])]{}, and [(\[eq:particledensity\])]{} has to be replaced by the transverse mass $m_\perp=\sqrt{m^2+p_\perp^2}$, in accordance with [eq. (\[eq:schwinger2\])]{}. The parameters $a$ and $b$, determined by the hadronic phase space and (the imaginary part of) the string action, have been tuned to LEP data, which in our case gives $a=0.42$ and $b=0.4$.

Baryon production {#sec:baryonprod}
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Besides including different quark species, the relations in [eqs. (\[eq:Lund\])]{} and [(\[eq:split\])]{} must also be generalized to include baryon production and effects of spin interaction. A quark and an antiquark can combine to a total spin 1 or 0. Fits to data favour a $\pi:\rho$ ratio about $1:1$ (rather than the $1:3$ expected from naive spin counting), which also can be understood as a result of normalization of the wavefunction in the tunneling process [@Andersson:1982if; @Andersson:1983ia].

A baryon–antibaryon pair can be formed if the string can break by the production of a diquark–antidiquark pair forming an antitriplet and a triplet respectively [@Andersson:1981ce]. Such a process would be suppressed by a larger effective diquark mass. In this case 