arXiv subjects

Oleksandr Tomalak

Publications and source records attributed to Oleksandr Tomalak.

At least 19 recordsLinked to original sources

arXiv2026

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

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 improves convergence and reduces the QED radiative correction to the experiment-over-lattice-QCD ratio $g_A/\left(g^\mathrm{QCD}_A g_V\right)$. $Δ$ resonance increases the pion-induced QED radiative corrections to IBD by a factor $1.2$-$1.3$.

hep-ph↗

arXiv2026

QED nuclear medium effects at EicC

We evaluate quantum electrodynamics (QED) nuclear medium effects under experimental conditions at the future Electron-ion collider in China (EicC). We consider neutral-current and charged-current elastic scattering, as well as neutral-current and charged-current deep inelastic scattering. We compute cross-section corrections at first order in the opacity expansion and estimate kinematic modifications due to multiple rescattering within the nucleus. We perform the first calculations of charged-current deep inelastic scattering and polarized scattering. We present results for the anticipated $^{197}_{79}\mathrm{Au},~^{208}_{82}\mathrm{Pb},$ and $^{238}_{92}\mathrm{U}$ nuclei and extrapolate these calculations to the lighter $^{40}_{20}\mathrm{Ca}$ isotope. We find that QED nuclear medium effects are non-negligible when extracting the process-independent non-perturbative structure of nucleons and nuclei at the EicC.

nucl-th↗

arXiv2026

Theory of inverse beta decay for reactor antineutrinos

Inverse beta decay (IBD), $\overlineν_e p \to e^+ n \left( γ\right)$, is the main detection channel for reactor antineutrinos in water- and hydrocarbon-based detectors. As reactor antineutrino experiments now target sub-percent-level sensitivity to oscillation parameters, a precise theoretical description of IBD, including recoil, weak magnetism, nucleon structure, and radiative corrections, becomes essential. In this work, we give a detailed and precise calculation of the total and differential cross sections for radiative IBD, $\overlineν_e p \to e^+ n γ$. We use a heavy baryon chiral perturbation theory framework, systematically incorporating electroweak, electromagnetic, and strong-interaction corrections. We derive new analytic cross-section expressions, clarify the collinear structure of radiative corrections, and provide a systematic uncertainty analysis. We also discuss phenomenological applications for reactor antineutrino experiments, e.g., JUNO, and neutron decay. Our results enable sub-permille theoretical precision, supporting current and future experiments.

hep-ph↗

arXiv2026

Radiative corrections to inverse beta decay: a precision analysis for reactor neutrinos

We present a complete calculation of radiative corrections to the inverse beta decay reaction, $\overlineν_e + p \rightarrow e^+ + n$, at reactor antineutrino energies using heavy-baryon chiral perturbation theory. Our analysis consistently incorporates quantum electrodynamics, chromodynamics, and electroweak contributions for the first time within this framework. We provide updated, high-precision cross-section predictions with a full error budget and present the positron energy spectrum, including radiative effects. The results are essential for normalizing the reactor antineutrino flux, determining neutrino oscillation parameters with subpercent accuracy, and searching for new physics at nuclear power plants.

hep-ph↗

arXiv2026

QED radiative corrections in inverse beta decay from virtual pions

Inverse beta decay (IBD), $\overlineν_e p \to e^+ n \left( γ\right)$, is the main detection channel for reactor and supernova antineutrinos. To provide precise IBD cross sections at antineutrino energies $E_{\overlineν_e} \gtrsim 10~\mathrm{MeV}$, we evaluate radiative corrections from virtual pions within the framework of heavy baryon chiral perturbation theory. At leading order, only the pion isospin-breaking contributions are not suppressed by the electron mass. At next-to-leading order, besides recoil effects, only the Wilson coefficient $c_4$ contributes to the kinematic dependence. However, its precise value is not relevant for IBD at relatively low energies since all next-to-leading order radiative corrections are relatively small. We find the kinematic dependence of the pion-induced QED radiative corrections at the level and below the uncertainty from the momentum dependence of the nucleon form factors. Our results enable sub-permille theoretical precision of charged-current elastic (anti)neutrino-nucleon scattering at antineutrino energies $E_{\overlineν_e} \gtrsim 10~\mathrm{MeV}$.

hep-ph↗

arXiv2026

Radiative corrections in neutral-current (anti)neutrino elastic scattering at $\text{GeV}$ energies I: Nucleon targets

We introduce radiative corrections in neutral-current (anti)neutrino-nucleon elastic scattering at $\text{GeV}$ energies within the effective field theory framework. We factorize cross sections into soft and hard functions, clarify the (anti)neutrino flavor dependence at both amplitude and cross-section levels, and improve the quantum chromodynamics (QCD) contributions to low-energy neutral-current processes. The radiative corrections at the single-nucleon level reach a magnitude comparable to the contributions from strange quarks. We also compare our results with the experimental data from BNL E734 and MiniBooNE collaborations, finding excellent agreements with the experimental data.

hep-ph↗

arXiv2026

Radiative corrections to the nucleon isovector $g_V$ and $g_A$

Electroweak, QCD, and QED radiative corrections to the nucleon low-energy coupling constants $g_V$ and $g_A$ are enhanced by large perturbative logarithms between the electroweak and hadronic scale, as well as between the hadronic scale and the low-energy MeV scale. Additionally, higher-order pion-mass splitting corrections to the nucleon axial-vector charge might be large. By consistently incorporating these effects, we provide an updated relation between the lattice-QCD and physical $g_A$, finding a total radiative correction of $3.5(2.1)\%$ ($5.6(0.7)\%$). This leads to an expected lattice-QCD result of $g^{\mathrm{QCD}}_A = 1.265(26)$ ($g^{\mathrm{QCD}}_A = 1.240(9)$) when based on a combination of lattice-QCD and data-driven (or only data-driven) inputs, respectively. Future phenomenological, chiral perturbation theory, and lattice-QCD studies can improve both the central value and the uncertainty of this estimate.

hep-ph↗

arXiv2026

Nucleon axial-vector form factor and radius from radiatively-corrected antineutrino scattering data

The nucleon axial-vector form factor, $G_A$, is critical to determine the electroweak interactions of leptons with nucleons. Important examples of processes influenced by $G_A$ are elastic (anti)neutrino-nucleon scattering and muon capture by the proton. Sparse experimental data results in a large uncertainty on the momentum dependence of $G_A$ and has motivated the consideration of new experimental probes and first-principles lattice quantum chromodynamics (QCD) evaluations. The comparison of new and precise theoretical predictions for $G_A$ with future experimental data necessitates the application of radiative corrections to experimentally-observable processes. We apply these corrections in the extraction of $G_A$ and the associated axial-vector radius from the recent MINERvA antineutrino-hydrogen data, compare the effects from radiative corrections to other uncertainties in neutrino scattering experiments, and discuss the comparison of lattice QCD evaluations to experimental measurements.

hep-ph↗

arXiv2026

Resonance Contributions to Radiative Corrections in Charged-Current Elastic (Anti)Neutrino-Nucleon Scattering at GeV Energies

We present the first evaluation of virtual resonance contributions to the charged-current (anti)neutrino-nucleon elastic scattering at GeV energies, focusing on the dominant $Δ(1232)$ resonance. We approximate the vector part of the $N \to Δ$ transition by the leading magnetic dipole term. Our results for the cross-section corrections at fixed neutrino energy indicate the permille-level contribution of resonance intermediate states to the elastic and radiative scattering cross sections. This calculation exhibits the expected infrared behavior of the invariant amplitudes and unpolarized cross sections. Our findings provide important insights into inelastic excitations in the charged-current (anti)neutrino-nucleon elastic scattering at GeV energies.

hep-ph↗

arXiv2026

Reducing Hadronic Uncertainty in Low-Energy Neutral-Current Processes

We analyze the hadronic uncertainty from light-quark loops coupled to (anti)neutrino in low-energy neutral-current (anti)neutrino scattering, estimated at the $3$-$4$ permille level. This uncertainty arises from limited knowledge of the charge-isospin correlation function of quark currents. We study the charge-charge and charge-isospin correlators within $\mathrm{SU}(2)$ and $\mathrm{SU}(3)$ chiral perturbation theory (ChPT). In $\mathrm{SU}(2)$ ChPT, the two correlators are identical to all orders in the chiral and electromagnetic expansions. We further perform a leading-order $\mathrm{SU}(3)$ ChPT calculation and discuss the relevant counterterms. Our findings reduce the hadronic uncertainty in neutral-current processes such as (anti)neutrino-electron and coherent elastic (anti)neutrino-nucleus scattering by a factor $\sim 35$.

hep-ph↗

arXiv2025

QED nuclear medium effects at EIC energies

We present the first calculation of quantum electrodynamics (QED) nuclear medium effects under the experimental conditions of future Electron-Ion Collider (EIC) experiments. Our work offers numerical estimates, particularly in the context of inclusive deep inelastic scattering on a $^{208}_{82}\mathrm{Pb}$ nucleus. While prior studies have predominantly focused on elastic scattering, our investigation extends to the more complex scenarios of inelastic processes within a nuclear medium. Our findings suggest that the cross-section corrections due to QED nuclear medium effects could be substantial, reaching or exceeding the level of experimental precision. This work further compares the effects of single re-scattering events with those of multiple re-scatterings, as particles travel the nuclear volume. We estimate the dominant source of the uncertainties associated with our formalism by varying the scale of the atomic physics where the screening of the electric field of the nucleus happens. This calculation not only contributes to the understanding of QED nuclear medium effects, but also offers a path to a more precise extraction of the process-independent non-perturbative structure of nuclei.

nucl-th↗

arXiv2025

Effective field theory for radiative corrections to charged-current processes II: Axial-vector coupling

We discuss the hadronic structure-dependent radiative corrections to the axial-vector coupling that controls single-nucleon weak charged-current processes -- commonly denoted by $g_A$. We match the Standard Model at the GeV scale onto chiral perturbation theory at next-to-leading order in the one-nucleon sector, in the presence of electromagnetic and weak interactions. As a result, we provide a representation for the corrections to $g_A$ in terms of infrared finite convolutions of simple kernels with the single-nucleon matrix elements of time-ordered products of two and three quark bilinears (vector, axial-vector, and pseudoscalar). We discuss strategies to determine the required non-perturbative input from data, lattice-QCD (+QED), and possibly hadronic models. This work paves the way for a precise comparison of the values of the ratio $g_A/g_V$ extracted from experiment and from lattice-QCD, which constrain physics beyond the Standard Model.

nucl-th↗

arXiv2024

Dispersion relation formalism for the two-photon exchange correction to elastic muon-proton scattering: elastic intermediate state

We evaluate the two-photon exchange correction to the unpolarized cross section in the elastic muon-proton scattering within dispersion relations. One of the six independent invariant amplitudes requires a subtraction. We fix the subtraction function to the model estimate of the full two-photon exchange at one of three MUSE beam energies and make a prediction for the two other energies. Additionally, we present single and double polarization observables accounting for the lepton mass.

hep-ph↗

arXiv2024

Constraints on new physics with (anti)neutrino-nucleon scattering data

New physics contributions to the (anti)neutrino-nucleon elastic scattering process can be constrained by precision measurements, with controlled Standard Model uncertainties. In a large class of new physics models, interactions involving charged leptons of different flavor can be related, and the large muon flavor component of accelerator neutrino beams can mitigate the lepton mass suppression that occurs in other low-energy measurements. We employ the recent high-statistics measurement of the cross section for $\barν_μp \to μ^+ n$ scattering on the hydrogen atom by MINERvA to place new confidence intervals on tensor and scalar neutrino-nucleon interactions: $\mathfrak{Re} C_T = -1^{+14}_{-13} \times 10^{-4}$, $|\mathfrak{Im} C_T| \le 1.3 \times 10^{-3}$, and $|\mathfrak{Im} C_S| = 45^{+13}_{-19} \times 10^{-3}$. These results represent a reduction in uncertainty by a factor of $2.1$, $3.1$, and $1.2$, respectively, compared to existing constraints from precision beta decay.

hep-ph↗

arXiv2024

Medium-induced photon bremsstrahlung in neutrino-nucleus, antineutrino-nucleus, and electron-nucleus scattering from multiple QED interactions

Interactions of charged leptons with nuclei and the naive tree-level kinematics of these processes are affected by radiation of photons induced by the QED nuclear medium. We evaluate cross-section modifications at leading orders of the number of correlated interactions inside the nucleus, known as the opacity expansion. We derive results for soft and collinear types of the bremsstrahlung at the first three orders in opacity and generalize them to higher orders. We present the leading in opacity energy spectra of soft and collinear photons and radiative energy loss inside the nucleus for experiments with lepton kinematics in the GeV energy range. At leading power of the Glauber soft-collinear effective field theory, the soft radiation is further resummed to all orders both in opacity and in the electromagnetic coupling constant. We find that the soft and collinear medium-induced radiation is vacuumlike, and additional corrections are power suppressed. Despite the negligible modification to the induced photon spectra, the nuclear medium-induced radiation sizably affects the broadening of charged leptons in the direction orthogonal to their propagation.

hep-ph↗

arXiv2024

Invariant amplitudes, unpolarized cross sections, and polarization asymmetries in (anti)neutrino-nucleon elastic scattering

At leading order in weak and electromagnetic couplings, cross sections for (anti)neutrino-nucleon elastic scattering are determined by four nucleon form factors that depend on the momentum transfer $Q^2$. Including radiative corrections in the Standard Model and potential new physics contributions beyond the Standard Model, eight invariant amplitudes are possible, depending on both $Q^2$ and the (anti)neutrino energy $E_ν$. We review the definition of these amplitudes and use them to compute both unpolarized and polarized observables including radiative corrections. We show that unpolarized accelerator neutrino cross-section measurements can probe new physics parameter space within the constraints inferred from precision beta decay measurements.

hep-ph↗

arXiv2024

Nucleon axial-vector form factor and radius from future neutrino experiments

Precision measurements of antineutrino elastic scattering on hydrogen from future neutrino experiments offer a unique opportunity to access the low-energy structure of protons and neutrons. We discuss the determination of the nucleon axial-vector form factor and radius from antineutrino interactions on hydrogen that can be collected at the future Long-Baseline Neutrino Facility, and study the sources of theoretical and experimental uncertainties. The projected accuracy would improve existing measurements by $1$ order of magnitude and be competitive with contemporary lattice-QCD determinations, potentially helping to resolve the corresponding tension with measurements from (anti)neutrino elastic scattering on deuterium. We find that the current knowledge of the nucleon vector form factors could be one of the dominant sources of uncertainty. We also evaluate the constraints that can be simultaneously obtained on the absolute $\bar ν_μ$ flux normalization.

hep-ph↗

arXiv2023

Broadening of particle distributions in electron- and (anti)neutrino-nucleus scattering from QED interactions

Proper interpretation of past, current, and future data on lepton-nucleus reactions requires a clear separation between quantum electrodynamics (QED) and strong interaction effects inside the nucleus. First studies of QED in-medium lepton dynamics have set a theoretical framework to derive electron-nucleus and (anti)neutrino-nucleus cross-section corrections. We employ this approach to quantitatively compute the effects of Glauber photon-mediated multiple re-scattering within the nuclear medium. We find that the relativistic charged lepton acquires momentum of order $10~\mathrm{MeV}$ transverse to its direction of propagation inside the nucleus. This broadening sizably deflects expected electron tracks and suppresses scattering cross sections. Precise extraction of the nucleon and nuclear structure by electron and muon probes should, thus, take the QED nuclear medium angular redistribution of particles into account. Our results further show that the associated effects in (anti)neutrino-nucleus scattering with measured final-lepton energy are significant only at the kinematical endpoints.

hep-ph↗