Meson dynamics from locally exciting a particle-conserving $Z_2$ lattice gauge theory

Vaibhav Sharma; Kaden R. A. Hazzard

doi:10.22331/q-2025-10-01-1872

Meson dynamics from locally exciting a particle-conserving $Z_2$ lattice gauge theory

Vaibhav Sharma and Kaden R. A. Hazzard

Department of Physics and Astronomy, Rice University, Houston, TX 77005
Smalley-Curl Institute, Rice University, Houston, TX 77005

Published:	2025-10-01, volume 9, page 1872
Editor:	Tommaso Macrì
Eprint:	arXiv:2503.02791v2
Doi:	https://doi.org/10.22331/q-2025-10-01-1872
Citation:	Quantum 9, 1872 (2025).

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Abstract

Quantum simulation of lattice gauge theories is an important avenue to gain insights into both particle physics phenomena and constrained quantum many-body dynamics. There is a growing interest in probing analogs of high energy collision phenomena in lattice gauge theories that can be implemented on current quantum simulators. Motivated by this, we characterize the confined mesons that originate from a local high energy excitation in a particle-conserving 1D $Z_2$ lattice gauge theory. We focus on a simple, experimentally accessible setting that does not require preparation of colliding wavepackets and isolates the effects of gauge field confinement strength and initial state energy on the nature of propagating excitations. We find that the dynamics is characterized by the propagation of a superposition of differently sized mesons. The linear confinement leads to meson size oscillations in time. The average meson size and oscillation frequency are controlled by the strength of the gauge field confinement. At a constant confinement field, the average meson length is controlled by the initial excitation's energy. Higher energies produce longer mesons and their effective mass depends strongly on their size: longer mesons propagate more slowly out of the central excitation. Mesons of different sizes get spatially filtered with time due to different speeds. We show that this phenomenology is a consequence of linear confinement and remains valid in both the strong and weak confinement limit. We present simple explanations of these phenomena supported by exact numerics.

Featured image: An illustration of dynamics in a lattice gauge theory model. Energy injected in a localized region leads to propagation of a meson that is in a superposition of different sizes. The longer mesons trail the smaller ones due to a speed differential.

Popular summary

Gauge theories describe the forces governing fundamental particles in our universe, but simulating their behavior on classical computers is challenging. Quantum simulation offers a path forward, especially for studying high energy processes such as particle collisions. Instead of colliding particles, this work studies what happens when we inject some energy into a small region, creating a localized ‘hot spot’ that is easier to implement in experiments. We focus on a simplified gauge theory model in one dimension and find that the resulting dynamics is characterized by the propagation of mesons (confined bound state of two particles). These mesons do not have a fixed size and instead are in a superposition of different sizes. The average meson size oscillates in time and can be tuned by the amount of energy injected initially. Furthermore, the speed of propagation of a meson is inversely related to its size. As a result, the mesons get spatially separated according to their size. A distant detector would first detect smaller mesons, while larger ones would arrive later. This work is an important step in understanding the building blocks of collision phenomena in gauge theories and sheds light on how initial energy shapes the dynamics.

► BibTeX data

@article{Sharma2025mesondynamicsfrom,
  doi = {10.22331/q-2025-10-01-1872},
  url = {https://doi.org/10.22331/q-2025-10-01-1872},
  title = {Meson dynamics from locally exciting a particle-conserving {$Z_2$} lattice gauge theory},
  author = {Sharma, Vaibhav and Hazzard, Kaden R. A.},
  journal = {{Quantum}},
  issn = {2521-327X},
  publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}},
  volume = {9},
  pages = {1872},
  month = oct,
  year = {2025}
}

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