.. _sphx_glr_api_gallery_particle_qcd:

Quantum chromodynamics
-------------------------

Confinement and string breaking, from
:mod:`physicskit.particle.confinement`.


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    <div class="sphx-glr-thumbcontainer" tooltip="Gross, Wilczek, and Politzer (1973) showed that the strong coupling decreases at short distances (asymptotic freedom), the opposite of QED -- and, at long distances, lattice QCD (systematized by Wilson, 1974) confirms the coupling grows enough to confine quarks permanently inside color-neutral hadrons, via a linear potential V(r)=\kappa r at large separation. This example evolves a receding quark-antiquark pair with string_break_chain: the confining string&#x27;s stored energy, string_tension_energy, grows without bound as the quarks separate -- unlike a Coulomb-like potential that would let them escape to infinity -- until it exceeds the threshold to pair-produce a new light quark-antiquark pair from the vacuum and the string breaks, repeatedly, rather than ever freeing a single isolated quark.">

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  .. image:: /api/gallery/particle/qcd/images/thumb/sphx_glr_plot_01_confinement_thumb.png
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  :doc:`/api/gallery/particle/qcd/plot_01_confinement`

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      <div class="sphx-glr-thumbnail-title">Asymptotic freedom and confinement: a receding quark pair's string</div>
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.. toctree::
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   /api/gallery/particle/qcd/plot_01_confinement