su3_singlet.py โ€” src/35-hadrons

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1#!/usr/bin/env python32# WP1 - the colour-neutral baryon as the centre-neutral triality invariant.3#4# Framed-rational / 1-algebra only: all arithmetic is in the finite field F_4 and in Z.5# No continuum, no RNG, no logs. We build SU(3, F_2) exactly (the order-216 instance the6# string-tension report D6b uses), read off its centre, and derive the colour-singlet rule7# (product of colour characters = trivial rep) as neutrality under that centre.8#9# F_4 = {0,1,w,w^2}, char 2.  Codes: 0=0, 1=1, w=2, w^2=3 (2-bit vectors over {1,w}).10#   addition  = XOR of codes (char-2 vector space)11#   F_4^* is cyclic of order 3 (w^3 = 1)12#   Frobenius conjugation x|->x^2 is the field involution defining the Hermitian form.1314from itertools import product1516EXP = {1: 0, 2: 1, 3: 2}          # code -> discrete log base w17ANTI = {0: 1, 1: 2, 2: 3}         # discrete log -> code1819def fadd(a, b):                   # F_4 addition20    return a ^ b2122def fmul(a, b):                   # F_4 multiplication23    if a == 0 or b == 0:24        return 025    return ANTI[(EXP[a] + EXP[b]) % 3]2627def fconj(a):                     # Frobenius x -> x^2  (the unitary involution)28    return 0 if a == 0 else ANTI[(2 * EXP[a]) % 3]2930# 3x3 matrices over F_4 as flat 9-tuples (row-major).31I3 = (1, 0, 0, 0, 1, 0, 0, 0, 1)3233def matmul(A, B):34    C = [0] * 935    for i in range(3):36        for j in range(3):37            s = 038            for k in range(3):39                s = fadd(s, fmul(A[3 * i + k], B[3 * k + j]))40            C[3 * i + j] = s41    return tuple(C)4243def dagger(A):                    # conjugate transpose (Hermitian adjoint), form H = I44    return tuple(fconj(A[3 * j + i]) for i in range(3) for j in range(3))4546def det3(A):47    a, b, c, d, e, f, g, h, i = A48    t1 = fmul(a, fadd(fmul(e, i), fmul(f, h)))     # char 2: minus = plus49    t2 = fmul(b, fadd(fmul(d, i), fmul(f, g)))50    t3 = fmul(c, fadd(fmul(d, h), fmul(e, g)))51    return fadd(fadd(t1, t2), t3)5253# --- build SU(3, F_2) = { U in M_3(F_4) : U^dag U = I, det U = 1 } by exact enumeration ---54print("== WP1: building SU(3, F_2) over F_4 (exact, framed-rational) ==")55G = []56for M in product(range(4), repeat=9):57    if det3(M) != 1:58        continue59    if matmul(dagger(M), M) == I3:60        G.append(M)61Gset = set(G)62order = len(G)63print(f"  |SU(3,F_2)| = {order}    (group-theory value q^3 (q^3+1)(q^2-1) = 8*9*3 = 216)")64assert order == 216, order6566# --- centre: elements commuting with the whole group ---67centre = [g for g in G if all(matmul(g, h) == matmul(h, g) for h in G)]68scalars = [tuple(fmul(lam, x) for x in I3) for lam in (1, 2, 3)]   # I, wI, w^2 I69print(f"  |Z(SU(3,F_2))| = {len(centre)}   centre = scalar matrices {{I, wI, w^2 I}} : "70      f"{set(centre) == set(scalars)}")71print(f"  centre is cyclic of order {len(centre)}  ->  Z_3  (the colour triality centre, gcd(3,q+1)=3)")72assert len(centre) == 3 and set(centre) == set(scalars)7374# the centre acts on the fundamental rep (the colour 3) by the scalar w:75#   a state of n quarks minus m antiquarks picks up w^(n-m) under the central generator wI.76# colour-singlet  <=>  invariant under the centre  <=>  w^(n-m) = 1  <=>  3 | (n - m).77print("\n== the colour-singlet rule = centre (Z_3) neutrality = triality 0 (mod 3) ==")78def triality(nq, naq):            # n quarks, n antiquarks ; quark triality +1, antiquark -179    return (nq - naq) % 380states = [81    ("single quark q",        1, 0),82    ("diquark qq",            2, 0),83    ("meson  q qbar",         1, 1),84    ("BARYON qqq",            3, 0),85    ("antibaryon qbar^3",     0, 3),86    ("tetraquark qq qbar^2",  2, 2),87    ("pentaquark q^4 qbar",   4, 1),88]89for name, nq, naq in states:90    t = triality(nq, naq)91    colourless = (t == 0)92    print(f"  {name:24s} triality = {t}  ->  {'COLOUR-SINGLET' if colourless else 'confined (not colourless)'}")9394# the baryon is the totally antisymmetric eps_{abc} invariant: Lambda^3 of the 3 is the trivial rep.95# we verify directly that the determinant (the eps_{abc} contraction of three colour-3 columns)96# is invariant under the group, i.e. transforms in the trivial rep:97print("\n== baryon = eps_{abc} (Lambda^3 of the colour 3) is the trivial rep ==")98inv = all(det3(g) == 1 for g in G)   # det(g . column-frame) = det(g) det(frame) = det(frame)99print(f"  det(U) = 1 for every U in SU(3,F_2): {inv}  -> the eps_abc contraction of three quark")100print( "  colour vectors is SU(3)-invariant: the baryon qqq is the unique colour singlet (Lambda^3 3 = 1).")101assert inv102103print("\nWP1 PASS: colour SU(3,F_2) built exactly (order 216, centre Z_3); the colour-singlet")104print("baryon is the centre-neutral triality-0 invariant eps_{abc}, derived not posited.")105