arXiv subjects

Jack Brand

Publications and source records attributed to Jack Brand.

4 recordsLinked to original sources

arXiv2026

Jet Quenching in the Smallest Hadronic Collision Systems

We present perturbative quantum chromodynamics (pQCD) predictions for high-momentum particle yield modification in very light ion collisions - ${}^{10}\mathrm{B}+{}^{10}\mathrm{B}$, ${}^{6}\mathrm{Li}+{}^{6}\mathrm{Li}$, ${}^{4}\mathrm{He}+{}^{4}\mathrm{He}$, and ${}^{3}\mathrm{He}+{}^{3}\mathrm{He}$ - with and without medium-induced energy loss. We find non-trivial suppression in symmetric systems from ${}^{208}\mathrm{Pb}+{}^{208}\mathrm{Pb}$ to ${}^{3}\mathrm{He}+{}^{3}\mathrm{He}$ and in asymmetric $A+B$ systems, with the suppression scaling approximately as $R_{AB} \simeq (\sqrt{AB})^{1/3}$. Further, we find that ${}^{3}\mathrm{He}$ and ${}^{6}\mathrm{Li}$ offer particularly clean environments for observing final-state partonic energy loss from quark-gluon plasma (QGP) formation in extremely small systems. Finally, we show that energy loss models generically predict $v_2\{\mathrm{SP}\} \approx 0$ in small systems, indicating that the large measured $v_2 > 0$ in $p+{}^{208}\mathrm{Pb}$ is not due to energy loss.

hep-ph↗

arXiv2026

Morse diagrams, Murasugi sums, and the mapping class group

A combinatorial Morse structure encodes a mapping class for a surface with boundary, and the data may be efficiently represented via a Morse diagram. This diagram determines an open book decomposition of a 3-manifold, and hence, a contact structure on that 3-manifold. We examine how combinatorial Morse structures behave under the connect sum of open books, with particular attention paid to the case of negative stabilisation. This leads to a diagrammatic criterion for detecting overtwisted contact structures. Finally, in the case of open books with one-holed torus pages, we classify all the Morse diagrams associated to a fixed open book decomposition.

math.GT↗

arXiv2025

From Lead to Helium: Discovery Potential for Jet Quenching in the Smallest Collision Systems

We present perturbative quantum chromodynamics (pQCD) predictions for the modification to the yield of high-momentum particles in very light ion collisions - ${}^{10}\mathrm{B} + {}^{10}\mathrm{B}$, ${}^{6}\mathrm{Li} + {}^{6}\mathrm{Li}$, ${}^{4}\mathrm{He} + {}^{4}\mathrm{He}$, and ${}^{3}\mathrm{He} + {}^{3}\mathrm{He}$ - both with and without medium-induced energy loss. We show that there is non-trivial suppression expected from our partonic energy loss model in symmetric systems from ${}^{208}\mathrm{Pb} + {}^{208}\mathrm{Pb}$ to ${}^{3}\mathrm{He} + {}^{3}\mathrm{He}$ and in asymmetric systems $A + B$, and that the energy loss scales approximately with $(\sqrt{A B})^{1 / 3}$. Further, we find that deep inelastic scattering measurements in ${}^{3}\mathrm{He}$ and ${}^{6}\mathrm{Li}$ tightly constrain the nPDF baseline, making these isotopes a particularly clean environment for observing final-state partonic energy loss induced by the formation of a quark-gluon plasma in these very small systems.

hep-ph↗

arXiv2022

Arc diagrams on 3-manifold spines

We develop a theory of link projections to trivalent spines of 3-manifolds. We prove a Reidemeister Theorem providing a set of combinatorial moves sufficient to relate the projections of isotopic links. We also show that any link admits a crossingless projection to any special spine and we refine our theorem to provide a set of combinatorial moves sufficient to relate crossingless diagrams. Finally, we discuss the connection to Turaev's shadow world, interpreting our result as a statement about shadow equivalence of a class of 4-manifolds.

math.GT↗