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GAUGE · INTERACTIVE EXPLORERS

Explore exact singlet-loop energies and gaps

Compare an exact finite-model response with its leading approximation. The same Hamiltonian determines the ground energy, its holonomy dependence and the gap above it.

Mohamed Haj YousefUpdated 6 min read

Assumptions, results and research status

An explicit finite mathematical example with declared inputs, conventions and scope.

Assumptions

  • The operator, state family or representations described on this page are supplied as model inputs.
  • Every exported quantity uses the units and conventions printed beside the calculation.

Results

  • The default example, tables and equations remain readable without JavaScript.
  • With JavaScript, changing valid inputs recomputes the declared model and enables numerical downloads.

Open questions

  • What additional source dynamics and physical matching would turn this example into a prediction of a specified physical system?

The declared model

The model pairs a mobile rank-m carrier with a stationary dual. A positive penalty Δ favors their singlet at a specified loop position, and hopping t transports the mobile carrier around four positions. A holonomy matrix W enters through its eigenangles. The free cycle eigenvalues are λak = 2t cos[(θa + 2πk)/4], and a rank-one resolvent equation determines the physical ground state.

The calculation uses Δ as its energy unit. Rank two explores eigenangles (θ,−θ). At rank three, choose either the balanced slice (θ,−θ,0) or the full diagonal family (θ,φ,−θ−φ). Varying both angles covers SU(3) conjugacy classes, with the permutation and periodic identifications explained in the two-angle domain guide. The φ input and family selector do not enter the rank-two calculation. The positive root lies above every free eigenvalue and is found in a guaranteed analytic bracket. [Exact singlet results, v20, Section 2]

Run the calculation

Exact singlet-loop response

Compare the exact energy shift of the declared finite singlet model with its leading weak-hopping loop term. Change the carrier rank, hopping and holonomy.

The singlet penalty Δ is the energy unit. Hopping is t/Δ; displayed energies and gaps are divided by Δ. Angles are radians.

Choose the model inputs

Exact energy shift 0.001072956 Δ; finite-model gap 0.6784925 Δ.

Exact E(W) − E(I), in Δ
0.00107295645
Leading loop term, in Δ
0.00136030346
Exact excitation gap, in Δ
0.678492492
Uniform finite-model bound, in Δ
0.08333333

SU(3): diag(exp(iθ),exp(−iθ),1). The selected eigenangles are 1.2, -1.2, 0 radians. The second SU(3) angle is inactive for this selection.

Exact and leading singlet-loop responseThe solid curve is the exact finite-model result; the dashed curve is the leading weak-hopping expression. The angle family and hopping are held as stated.Energy change / Δ000.001140.7850.002281.570.003422.360.004573.14Holonomy angle θ / radians
Exact energy change / Δ Leading loop term / Δ. The solid curve is the exact finite-model result; the dashed curve is the leading weak-hopping expression. The angle family and hopping are held as stated.
Selected finite-model quantities
QuantityValue
Ground energy E(W)/Δ-0.07849249223
Identity ground energy E(I)/Δ-0.07956544869
Root z/Δ1.078492492
Secular residual6.66e-16
Real trace Re Tr W1.72471551
Imaginary trace Im Tr W0
Loop cost m − Re Tr W1.275284
Exact Hessian κ̂ₘ/Δ0.0008392853737
Weak-hopping κloop/Δ0.001066666667
Absolute approximation error / Δ0.0002873470028

For W = exp(iX) close to identity, the convention is E(W) − E(I) = ½κ̂ₘ Tr X² + O(X⁴). Along the balanced slice, Tr X² = 2θ². The exact Hessian is positive when hopping is nonzero; it vanishes at t = 0.

Values across the displayed angle family
Energy shift and gap across the loop family
θ / radExact shift / ΔLeading shift / ΔGap / Δ
0000.6795654
0.31415930.000082170530.00010441280.6794833
0.62831850.00032081370.00040743040.6792446
0.94247780.00069302870.00087939150.6788724
1.2566370.0011629520.0014740970.6784025
1.5707960.0016850510.0021333330.6778804
1.8849560.0022084030.002792570.677357
2.1991150.0026816070.0033872750.6768838
2.5132740.0030578780.0038592360.6765076
2.8274330.0032998020.0041622540.6762656
3.1415930.0033832260.0042666670.6761822
Equations and conventions used
λak = 2t cos[(θa + 2πk)/4], k = 0,1,2,3.
(Δ/4m) Σa,k(z − λak)−1 = 1; E = Δ − z; gap = z − λ* ≥ Δ/(4m).
E(W) − E(I) ≈ [2t⁴/(mΔ³)] [m − Re Tr W].

A finite model with a unique ground state for the stated ranks and penalty. Its finite-dimensional excitation gap is not the four-dimensional Yang–Mills mass gap. At rank three, choose the balanced slice or the full diagonal two-angle family diag(exp(iθ),exp(iφ),exp(−i(θ+φ))). At rank two, the family selector and φ do not enter the SU(2) calculation.

Downloads include the chosen inputs, units and model scope. Values use standard floating-point arithmetic. Read the source and its version notes.

Try these comparisons

  1. Choose the balanced slice and weak hopping t/Δ = 0.1, then inspect the exact and leading curves. Both vanish at identity because the plotted quantity subtracts E(I).
  2. Increase hopping to 0.5. The leading term remains a well-defined expression, but it is a less accurate approximation to the exact response.
  3. Set t/Δ = 0. The model has E = 0, gap Δ and no loop response.
  4. Use a small nonzero θ and compare [E(W) − E(I)]/θ² with the displayed exact Hessian coefficient.

At rank three and t/Δ = 0.1, the identity energy is approximately −0.01999231644Δ, the identity gap is 0.81999231644Δ, and κ̂₃ is approximately 0.00006277560191Δ. These provide reproducible checkpoints independent of a measured physical coupling.

Interpret the result

The exact result has E = Δ − z and, for the stated ranks, gap = z − λ* ≥ Δ/(4m). Its local expansion is E(exp(iX)) − E(I) = ½κ̂mTr X² + O(X⁴). Along the balanced slice Tr X² = 2θ², so the coefficient of θ² is κ̂m. In the full two-angle SU(3) chart, a near-identity representative instead has Tr X² = θ²+φ²+(θ+φ)². The leading weak-hopping expression is 2t⁴[m − Re Tr W]/(mΔ³).

A finite-model gap is an exact result about this Hamiltonian. It does not establish the gap of a quantized gauge field, the infinite-volume vacuum or the four-dimensional continuum theory. The exact-model derivation and Hessian guide explain the result’s scope and the extension to independent rank-three and rank-two blocks.

Reproduce or extend the calculation

Download JSON to retain the inputs, units, model scope and full computed results. Download CSV for the displayed numerical family or ledger; its opening rows record the input settings and definitions. The tool uses local browser calculations and ordinary floating-point arithmetic.

For an independent check, use the worked example in the exercise collection and the linked source manuscript. A useful extension states which input or assumption changes and which comparison would test the change. See the research collaboration page for focused starting questions.

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Sources for this guide

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