We investigate the orientational ordering and close-packing behavior of a quasi-one-dimensional (q1D) system of hard superellipses, where the centers of the particles are confined to a line, but they can rotate freely within a two-dimensional plane. The particle shape is tuned between an ellipse and a rectangle by varying the deformation parameter ($n$). The elongation of the particle is changed using the aspect ratio ($k$). The pressure ratio between freely rotating and parallel hard superellipses, which displays a single peak, serves as an effective marker for the continuous structural change from quasi-isotropic to nematic ordering. Our findings reveal a competition between the parameters $k$ and $n$, with $k$ promoting nematic alignment and $n$ favoring tetratic ordering. Notably, in the close-packing regime, the packing properties become independent of $k$, as the relevant exponents depend solely on $n$. Furthermore, certain combinations of these exponents exhibit universality, remaining invariant with respect to particle shape.

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• Classical statistical mechanics
• Order parameters
• Packing & jamming problems
• 1-dimensional systems
• Exact solutions for many-body systems