HEP Lattice·hep-lat

Tue·Aug 25, 2026Tuesday·August 25, 2026

4 papers—1 primary·3 cross-listed

01
Calculation of neutron electric dipole moment from Lattice QCD
Thomas Blum🇺🇸 · Fangcheng He🇺🇸 · Taku Izubuchi🇺🇸 · Luchang Jin🇺🇸 · Hiroshi Ohki🇯🇵 · Sergey Syritsyn🇺🇸
Experimental constraints on the neutron electric dipole moment (nEDM) may imply strong-CP problem in QCD, or unnatural smallness of the QCD theta angle. In this work, we present a novel determination of the neutron electric dipole moment (nEDM) $d_{n}$ sensitivity to theta term from nonperturbative QCD on a lattice with background electric field. Using Feynman-Hellmann theorem, we compute nEDM from the matrix element of local topological charge density between nucleon ground states spatially polarized by an electric field. These states have mixed spatial parity, and we construct them using variational analysis. We obtain statistically significant signal for the theta induced nEDM from lattices with 2+1 dynamical domain wall fermions corresponding to pion masses of 340, 420, and 576 MeV and lattice spacing $a \approx 0.11 fm$ . After extrapolating to the physical point, we obtain $d_{n} = - 0.0050 (4) (8) θ ˉ$ e $\cdot$ fm. Comparison with the current experimental bound on nEDM implies constraint $∣ θ ˉ ∣ ≲ 1 0^{- 11}$ , which confirms existence of the strong-CP problem in QCD. Our pioneering work demonstrates that neutron EDM can be reliably determined from the local density of topological charge with robust control of systematic effects, and can be directly extended to other CP-violating interactions.
hep-lathep-exhep-ph1 citation
02
What Neural Network Field Theory Can and Cannot Realise on a Computer
Thomas R. Harvey🇺🇸
One aim of neural network field theory is to put a quantum or effective field theory on a computer, with the network ensemble itself as the theory. We ask how far that aim can be pushed for a function class regular enough to be computed with. Our main result is a no-go theorem with assumptions that hold for standard network architectures. We use it to separate four versions of neural network field theory, according to whether the defining object is the finite width ensemble or its infinite width limit, and whether the target we want to compute is a quantum or an effective field theory. Neither finite width interpretation is straightforwardly consistent. For finite width ensembles with finite variance at each point, the QFT interpretation fails reflection positivity, while the EFT interpretation establishes no scale separation by which the positivity violation can be placed outside its domain of validity. Of the two limit versions, one can be simulated in full and the other only in part, as only its smeared correlators are computable with a controlled error. As such, at the level of a controlled numerical computation, the QFT and EFT versions cannot be distinguished. One dimension escapes the obstruction, yet reflection positivity is shown to still fail there at every finite width for the cosine network. Two escapes from the theorem remain, giving up either finite variance at a point or exact rotation invariance, and we discuss both of these possibilities.
↳ hep-thcs.LGhep-lathep-ph+21 citation
03
$Δ$ resonance contributions to QED radiative corrections in neutron and inverse beta decay
Oleksandr Tomalak🇨🇳 · Yi-Bo Yang🇨🇳
We incorporate the $Δ (1232)$ resonance into pion-induced QED radiative corrections to neutron decay and inverse beta decay (IBD). Within the framework of heavy-baryon chiral perturbation theory with explicit $Δ$ degrees of freedom, we compute additional contributions and study their impact on IBD cross sections and on the renormalization of the nucleon isovector vector and axial-vector charges. $Δ$ resonance does not renormalize the vector charge. For the axial-vector charge, including the $Δ$ resonance restores power counting and significantly reduces the QED radiative correction to the experiment-over-lattice-QCD ratio $g_{A} / (g_{A}^{QCD} g_{V})$ , bringing it to zero within radiative-correction uncertainties. $Δ$ resonance increases the pion-induced QED radiative corrections to IBD by a factor $1.2$ - $1.3$ .
↳ hep-phhep-exhep-latnucl-ex+10 citations
04
Probing Glueball content of X(2370) through heavy quarkonium radiative decays and electron-positron annihilation
Ruilin Zhu🇨🇳 · Qiang Zhao🇨🇳
In this paper, we first analyze the light-cone distribution amplitudes of the pseudoscalar Glueball and point out that the two-gluon and quark-antiquark pair contributions naturally mix at the quantum loop level. Based on the $η - η^{'} - G - η_{c}$ tetra-mixing scheme and existing experimental results, we analyze the branching ratio of $J / ψ \to P + γ$ with pseudoscalar meson $P$ and extract the mixing parameters of the tetra-mixing scheme. We then successfully predict the branching ratio of $ψ (2 S) \to P + γ$ , which is found to be in good agreement with experimental results. We also find that the branching ratios of $J / ψ \to X (2370) + γ$ and $ψ (2 S) \to X (2370) + γ$ are highly sensitive to the Glueball-charmonium mixing angle: the destructive mixing interference in the branching ratio of $J / ψ \to X (2370) + γ$ occurs at $ϕ_{g c} \approx 0.01$ , whereas that in $ψ (2 S) \to X (2370) + γ$ occurs at $ϕ_{g c} \approx 0.11$ . Moreover, the $J / ψ \to X (2370) + γ$ branching ratio exhibits constructive mixing interference when the mixing angle is larger than $ϕ_{g c} \approx 0.02$ . Finally, we also study the electroproduction cross sections of pseudoscalar mesons. After excluding the resonance contributions, the theoretical calculations agree with the experimental measurements in order of magnitude, and we also present theoretical predictions for the electroproduction cross section of the $X (2370)$ . These theoretical results can be readily tested by current BESIII and Belle-II experiments, and further experimental measurements will reveal the intrinsic nature of the $X (2370)$ .
↳ hep-phhep-exhep-lat0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Calculation of neutron electric dipole moment from Lattice QCD

What Neural Network Field Theory Can and Cannot Realise on a Computer

Δ resonance contributions to QED radiative corrections in neutron and inverse beta decay

Probing Glueball content of X(2370) through heavy quarkonium radiative decays and electron-positron annihilation

Affiliations

$Δ$ resonance contributions to QED radiative corrections in neutron and inverse beta decay