HEP Lattice·hep-lat

Wed·Oct 14, 2026Wednesday·October 14, 2026

3 papers—1 primary·2 cross-listed

01
Perturbative Renormalization of Noether Currents in SYM with Improved Discretizations
Marios Costa · Elias Antoniou · Salomi Dimou · Constantinos Costa · Panos K. Chrysanthis · Gregoris Spanoudes · Haralambos Panagopoulos
We investigate the perturbative renormalization of Noether currents associated with chiral symmetry and supersymmetry transformations in $N = 1$ supersymmetric Yang-Mills theory, regularized on the lattice using improved discretizations. In particular, we study the chiral current and the supercurrent operator for a broad class of lattice actions: Wilson fermions with one-step stout-smeared links and a clover term, together with a family of Symanzik-improved gluon actions. Since the supercurrent mixes with both gauge-invariant and gauge-noninvariant operators, we compute the corresponding renormalization factors and mixing coefficients at one-loop order. We analyze the impact of improved gluon and gluino actions on this mixing pattern and investigate whether suitable choices of lattice parameters, such as the clover and stout coefficients, can reduce unwanted lattice artifacts at one loop. Our results provide perturbative input for the implementation of Ward identities and for matching lattice observables to their continuum counterparts, while also offering guidance for simulations aimed at restoring supersymmetry in the continuum limit.
hep-lat
02
Solutions of Roy equations for variable pion mass
Gilberto Colangelo
The Roy equations for the $S$ and $P$ waves are solved for pion masses below the physical value in the region between threshold and $s_{A} = 0.84 \GeV^{2}$ . The analysis is based on the assumption that the phenomenological input above $s_{A}$ can be used essentially unchanged. Moreover, for $M_{π} \leq M_{π, phys}$ , the chiral perturbation theory predictions for the two $S$ -wave scattering lengths provide a very reliable additional input to the Roy equations. The outcome is an accurate description of the $S$ and $P$ partial waves as the light-quark masses decrease towards the chiral limit. As a test of the approach, we evaluate the first few threshold parameters of the $S$ , $P$ , and $D$ waves via Wanders' sum rules and find excellent agreement with chiral perturbation theory across the entire range $0 \leq M_{π} \leq M_{π, phys}$ . We further solve the Roy equations for pion masses above the physical value (up to $240 \MeV$ ) and show that the resulting solutions agree well with existing lattice data at $M_{π} = 239 \MeV$ . The present work paves the way for analyses of lattice data that fully incorporate the constraints of analyticity, unitarity, and crossing symmetry, and provides the basis for an accurate study of the dependence of the $σ$ and $ρ$ resonances on the light-quark masses, both of which will be addressed in future work.
↳ hep-phhep-lat
03
Signal-to-noise problems in fault-tolerant quantum computation
Hyunwoo Oh
Quantum computation offers a promising alternative to classical Monte Carlo methods by naturally avoiding sign problems through unitary evolution. A common misconception follows from this: because quantum simulation sidesteps the sign problem, it is often assumed to be an essentially perfect substitute for classical sampling. This is false---quantum measurements are intrinsically stochastic, and estimating observables often requires a number of samples that grows exponentially with system size, time separation, or inverse temperature, exactly as in the classical signal-to-noise problem. In this work, we analyze the origin and structure of signal-to-noise problems in quantum computation, drawing parallels with classical Monte Carlo, and demonstrate that such noise persists even in sign-problem-free regimes. We discuss strategies to mitigate it, in particular a quantum generalization of Stein control variates construction, in which unbiased estimators are built from operator commutators $[X, A]$ and their discrete diagonal counterparts, and validate the approach with exactly solvable numerical examples that quantify the achievable variance reduction. Our results underscore that variance reduction, not merely sign-problem avoidance, is required to make quantum algorithms practically viable for many-body physics.
↳ quant-phhep-latnucl-th

Perturbative Renormalization of Noether Currents in SYM with Improved Discretizations

Solutions of Roy equations for variable pion mass

Signal-to-noise problems in fault-tolerant quantum computation