MyQCD

English | 中文

MyQCD provides executable audits for the lattice-QCD formulas used by PyQCD. It splits a physics report into SymPy-checkable derivations, a source registry, and independent operator-construction and Feynman-diagram layers. Reference libraries are read-only Git submodules; GPL-3.0 or unlicensed upstream content is never copied.

Install

pip install myqcd

Requirements: Python 3.10+ and SymPy 1.12+. The complete test suite is currently exercised on Python 3.12 with SymPy 1.14.

Check an installation without any source checkout:

python -m myqcd.operator_audit
python -m myqcd

python -m myqcd runs the core formula checks. When refer/papers/INDEX.md is unavailable it skips the paper inventory and reports verified_core_without_inventory; the core checks still run.

Documentation

• English — https://myqcd.readthedocs.io/en/latest/
• 中文 — https://myqcd.readthedocs.io/zh-cn/latest/

Repositories

Quick start

import sympy as sp

from myqcd import color, diagram_export, feynman, gamma, operators

assert gamma.gamma_basis_rank() == 16
assert gamma.trace_gamma_product((1, 1)) == 4
assert color.casimir_fundamental() == sp.Rational(4, 3)

operator = operators.BilinearOperator(
    name="O_V4", left_flavor="u", right_flavor="d", structure="V4"
)
assert operator.pyqcd_gamma_index == 4
assert operator.mass_dimension == 3

triangle = feynman.Diagram(
    vertices=("a", "b", "c"),
    edges=(
        feynman.Edge(0, 1, "gluon"),
        feynman.Edge(1, 2, "gluon"),
        feynman.Edge(2, 0, "gluon"),
    ),
)
assert triangle.loop_count == 1
assert diagram_export.to_tikz(triangle).startswith("%")

Operators and diagrams

myqcd exposes all 16 Dirac bilinears with exact parity/C signs, mass dimension, and PyQCD gamma indices:

The full table and the comparison with standard Dirac/SU(3) values are in Operators. The documentation renders the same formulas with LaTeX.

Diagram examples (two-point chain, three-gluon triangle, one-loop quark self-energy, two-loop sunset and Wick pairing) with loop counts and TikZ/DOT/SVG export are in Feynman diagrams.

What is inside

Entry points

python -m myqcd
python -m myqcd.operator_audit --root .
python -m myqcd.pyqcd_theory_audit --root .

python -m myqcd.operator_audit writes logs/data/operator_audit/operator_feynman_audit.json under the current directory and exits non-zero if any check fails.

Evidence boundary

• verified covers only the algebra, dimensions, finite-dimensional proxies and combinatorial identities that are actually checked.
• No claim is made for loop integrals, nonperturbative matrix elements, real ensembles, GPU numerics, soft/rapidity closure or the continuum limit.
• myqcd.color uses the Hermitian normalization Tr[T^aT^b] = +delta^{ab}/2; the historical SU(3) derivations in myqcd.derivations use the anti-Hermitian -delta^{ab}/2. The two conventions must not be mixed.
• Diagram export guarantees combinatorial structure and string format only; it does not prove symmetry factors or loop-integral results.

License

MIT. See LICENSE.