CyberSec Research

To study cross sections and polarization asymmetries for the processes $e p \to e n \pi^+$ and $e p \to e p \pi^0$ in the backward region, we develop a flexible phenomenological model for nucleon-to-pion transition distribution amplitudes ($\pi N$ TDAs), which are used in the QCD collinear factorization description of the scattering amplitudes. Our model is based on the two-component factorized Ansatz for the corresponding spectral densities, quadruple distribution. It takes into account the constraints for $\pi N$ TDAs arising from the threshold pion production theorem and also includes a forward limit contribution that can be fitted to experimental data. We examine the sensitivity of observable predictions to various modelling assumptions.

In preparation to the CROSS experiment at the Canfranc underground laboratory (Spain) $-$ aiming to search for neutrinoless double-beta ($0\nu\beta\beta$) decay of $^{100}$Mo using low-temperature detectors with heat-scintillation readout $-$ we report on development of a dedicated muon veto system. The need for the muon veto in CROSS is caused by a comparatively high residual cosmic muon flux at the experimental site ($\sim$20 $\mu$/m$^2$/h), being a dominant background in the region of interest (ROI) at $\sim$3 MeV. Thus, we installed the muon veto system around the CROSS low-background setup, forming four lateral, one top, and four bottom sectors. In this paper we describe the design, construction and operation of the CROSS muon veto system, as well as its optimization and validation by comparing dedicated Monte Carlo (MC) simulations of muons with low-temperature measurements in the setup. We demonstrate a stable operation of the veto system with the average trigger rates compatible with MC simulations. Also, we investigated two muon trigger logics based on coincidences with either 2 sectors or a single sector of the veto. The MC study shows that, in combination with the multiplicity cut of thermal detectors, these trigger logics allow to reject 99.2\% and 99.7\% of muon-induced events in the ROI, respectively. Despite a comparatively high dead time ($\sim$18\%) introduced by coincidences with any of nine sectors of the veto $-$ the adopted strategy $-$ the muon-induced background in the ROI of the CROSS experiment can be reduced down to $\sim$2 $\times 10^{-3}$ cnts/keV/kg/yr, i.e., an acceptable level compatible with a high-sensitivity $0\nu\beta\beta$ decay search foreseen in CROSS.

Gamma ($\gamma$) decay shapes the synthesis of heavy elements in neutron-rich nuclear environments of neutron star mergers, supplying the Universe with heavy elements. The low-energy pygmy dipole resonance (PDR) influences nuclear reaction rates of the rapid nucleosynthesis through enhanced $\gamma$ transitions. However, since it is difficult to reproduce astrophysical conditions in laboratories, PDR was previously observed only in $J = 1$ spin states. Here we report the first experimental observation of $J > 1$ components of PDR, identified in the $\beta$-delayed $\gamma$ decay of the J$^{\pi}$ = 3$^{-}$ spin-parity isomer of $^{80}$Ga. The data analysis, combined with decay information and theoretical calculations allows the identification of resonant structures below the neutron emission threshold of the neutron-rich germanium $^{80}$Ge as J$^{\pi} = (2,3)^-$ components of the PDR built on the low-lying J$^{\pi}$ = 2$^+$ quadrupole state. Our findings extend the concept of PDR beyond dipole states, with implications for nuclear structure theory and experiment, as well as the element production in the cosmos.

The GlueX experiment at Jefferson Lab has observed $p\bar{p}$ and, for the first time, $\Lambda\bar{\Lambda}$ and $p\bar{\Lambda}$ photoproduction from a proton target at photon energies up to 11.6 GeV. The angular distributions are forward peaked for all produced pairs, consistent with Regge-like $t$-channel exchange. Asymmetric wide-angle anti-baryon distributions show the presence of additional processes. In a phenomenological model, we find consistency with a double $t$-channel exchange process where anti-baryons are created only at the middle vertex. The model matches all observed distributions with a small number of free parameters. In the hyperon channels, we observe a clear distinction between photoproduction of the $\Lambda\bar{\Lambda}$ and $p\bar{\Lambda}$ systems but general similarity to the $p\bar{p}$ system. We report both total cross sections and cross sections differential with respect to momentum transfer and the invariant masses of the created particle pairs. No narrow resonant structures were found in these reaction channels. The suppression of $s\bar{s}$ quark pairs relative to $d\bar{d}$ quark pairs is similar to what has been seen in other reactions.

In the high-energy limit of QCD, scattering off nucleons and nuclei can be described in terms of Wilson-line correlators whose energy dependence is perturbative. The energy dependence of the two-point correlator, called the dipole amplitude, is governed by the Balitsky-Kovchegov (BK) equation. The initial condition for the BK equation can be fitted to the experimental data, which requires evolving the dipole amplitude for a large set of different parameter values. In this work, we train a transformer model to learn the energy dependence of the dipole amplitude, skipping the time-consuming numerical evaluation of the BK equation. The transformer predicts the learned dipole amplitude and the leading order inclusive deep inelastic scattering cross section very accurately, allowing for efficient fitting of the initial condition to the experimental data. Using this setup, we fit the initial condition of the BK equation to the inclusive deep inelastic scattering data from HERA and consider two different starting points $x_0$ for the evolution. We find better agreement with the experimental data for a smaller $x_0$. This work paves the way for future studies involving global fits of the dipole amplitude at leading order and beyond.

We present an extension of the MadGraph5_aMC@NLO framework that enables the automated calculation of leading-order cross sections for S-wave quarkonium and leptonium production within the non-relativistic QCD (NRQCD) and non-relativistic QED (NRQED) factorisation formalisms. The framework has been validated against a variety of benchmark processes, demonstrating robustness and flexibility for phenomenological studies. A key advantage of this implementation is its seamless integration with existing MadGraph5_aMC@NLO features, allowing computations not only within the Standard Model but also in a wide range of Beyond the Standard Model or Effective Field Theory scenarios via a modified Universal Feynman Output (UFO) interface. Furthermore, the framework maintains compatibility with standard Monte Carlo event generators for parton showering and hadronisation. Through numerous examples, we highlight that theoretical studies of quarkonium processes require careful consideration: the impact of subleading contributions is often difficult to predict using simple counting arguments based solely on the hierarchy of couplings and velocity-scaling rules.

For the first time, correlations among mixed-order moments of two or three flow harmonics $-$($v_{n}^{k},v_{m}^{l}$) and ($v_{n}^{k},v_{m}^{l}, v_{p}^{q}$), with $k$, $l$, and $q$ denoting the respective orders$-$are measured in xenon-xenon (XeXe) collisions and compared with lead-lead (PbPb) results, providing a novel probe of collective behavior in heavy ion collisions. These measurements compare a nearly spherical, doubly-magic ${}^{208}$Pb nucleus to a triaxially deformed ${}^{129}$Xe nucleus, emphasizing the sensitivity to dynamic nuclear deformation. The dependence of these results ($v_{n}$, $n$ = 2, 3, 4) on the shape and size of the nuclear overlap region is studied. Comparisons between $v_{2}$, $v_{3}$, and $v_{4}$ demonstrate the importance of $v_{3}$ and $v_{4}$ in exploring the nonlinear hydrodynamic response of the quark-gluon plasma (QGP) to the initial spatial anisotropy. The results constrain initial-state model parameters that influence the evolution of the QGP. The CMS detector was used to collect XeXe and PbPb data at nucleon-nucleon center-of-mass energies of $\sqrt{s_\mathrm{NN}}$ = 5.44 and 5.36 TeV, respectively. Correlations are extracted using multiparticle mixed-harmonic cumulants (up to eight-particle cumulants) with charged particles in the pseudorapidity range $\lvert\eta\rvert$ $\lt$ 2.4 and transverse momentum range 0.5 $\lt$ $p_\mathrm{T}$ $\lt$ 3 GeV/$c$.

We present recent updates from the CTEQ-JLab (CJ) global PDF analysis, focusing on the interplay and implementation systematics of the HT and offshell correction (CJ22ht). We also discuss preliminary results of the CJ25 global analysis, showing the impact of the full JLab 6 GeV datasets, that we recently collected in a comprehensive DIS database, and having a first look at early JLab 12 GeV measurements. We finally offer a few thoughts on how future data may help unraveling the nuclear and partonic dynamics in light nuclei.

We derive the one-pion exchange potential (OPEP) in the presence of a homogeneous magnetic field using chiral perturbation theory with nonrelativistic nucleons. Our approach is applicable not only to weak magnetic fields but also to strong ones up to around the pion-mass scale. The Green's function of charged pions is modified by the magnetic field, leading to changes in the nuclear force. By numerically evaluating the modified OPEP incorporating its spin and isospin dependencies, we show that the range of the potential decreases in both directions parallel and perpendicular to the magnetic field as the field strength increases. We also compute the resulting energy shift of the deuteron due to the modified OPEP, which can reach the order of 1 MeV around $|eB| = m_\pi^2$, which is comparable to the deuteron binding energy.

The isospin symmetry, originating from similar masses of $u$ and $d$ quarks, if exact would result in equal numbers of charged ($K^+$ and $K^{-}$) and neutral ($K^0$ and $\overline{K}^0$) mesons produced in collisions of isospin-symmetric atomic nuclei. The charged and neutral $K$ meson production in Ar+Sc collisions at a center-of-mass energy of 11.9 GeV per nucleon pair was measured by the NA61/SHINE Collaboration. The production of charged $K$ mesons at mid-rapidity is (18.4$\pm$6.1)\% higher than that of the neutral $K$ mesons.The models of hadron production, including known isospin-symmetry breaking effects, cannot explain the measurements.

The Cryogenic Underground Observatory for Rare Events (CUORE) experiment set the most stringent limit on the neutrinoless double-beta ($0\nu\beta\beta$) decay half-life of $^{130}$Te with 2 ton yr TeO$_2$ analyzed exposure. In addition to $0\nu\beta\beta$ decay, the CUORE detector -- a ton-scale array of nearly 1000 cryogenic calorimeters operating at $\sim$10 mK -- is capable of searching for other rare decays and interactions over a broad energy range. For our searches, we leverage the available information of each calorimeter by performing its optimization, data acquisition, and analysis independently. We describe the analysis tools and methods developed for CUORE and their application to build high-quality datasets for numerous physics searches. In particular, we describe in detail our evaluation of the energy-dependent detector response and signal efficiency used in the most recent search for $0\nu\beta\beta$ decay.

A wide range of scintillating bolometers is under investigation for applications in the search for rare events and processes beyond the Standard Model. In this work, we report the first measurement of a natural, non-molybdenum-doped, lithium tungstate (LWO) crystal operated underground as a scintillating cryogenic calorimeter. The detector achieved a baseline energy resolution of 0.5 keV RMS with a low-energy threshold of about 1.5 keV. The simultaneous readout of heat and light enabled particle identification, revealing a clear separation between $\beta/\gamma$, $\alpha$, and nuclear recoil populations above 300 keV, with a light-yield-based particle discrimination better than $6\sigma$. These results, fully comparable with those achieved with other compounds in the field, demonstrate that LWO is a promising candidate for rare-event searches. In particular, the combination of excellent radio-purity (with U/Th levels below 0.5 mBq/kg) and sensitivity to neutron interactions via the $^6$Li(n,$\alpha$)$^3$H reaction makes this material an attractive option for next-generation experiments on dark matter, coherent elastic neutrino-nucleus scattering, and spin-dependent interactions.

Heavy quarks offer an invaluable hard probe of the droplets of quark gluon plasma (QGP) formed in heavy ion collisions at the LHC and RHIC. Given their large mass, they are predominantly produced in hard scattering processes at the earliest moment of a collision and given their rarity they almost never annihilate with a heavy antiquark subsequently. This means that they experience, and probe, the entire history of the expanding, cooling, droplet of QGP from hydrodynamization through hadronization. Quantitative measurements of heavy quark final state observables therefore give us access to information about the transport properties of QGP as well as about medium modifications of hadronization. To date, the Hybrid strong/weak coupling Model of jet quenching has not included any implementation of the heavy-quark sector, which has made it impossible to confront its predictions with measurements of heavy quark and jet observables together, in a unified fashion. Here, we extend the Hybrid Model to investigate heavy quark observables for the first time. We introduce a strongly-coupled calculation of heavy-quark energy loss with the correct behavior when the heavy quarks are either ultrarelativistic or non-relativistic, Gaussian momentum broadening, and recombination of heavy quarks with medium partons using a local color neutralization model of hadronization. We compare our results for the suppression $R_{\rm AA}$ and azimuthal anisotropies $v_2$ of B- and D-mesons and $\Lambda_c$ baryons, the $R_{\rm AA}$ of B-tagged jets, as well as baryon-to-meson ratios, with available experimental data from ALICE, ATLAS and CMS.

Nuclear $\beta$ decay, a sensitive probe of nuclear structure and weak interactions, has become a precision test bed for physics beyond the Standard Model (BSM), driven by recent advances in spectroscopic techniques. Here we introduce tracking spectroscopy of $\beta$-$\gamma$ cascades, a method that reconstructs decay vertices while simultaneously detecting $\beta$ particles and all associated de-excitation energies. Using the PandaX-4T detector operated as a tracking spectrometer, we obtain a precise and unbiased decay scheme of $^{214}$Pb, a key background isotope in searches for dark matter and Majorana neutrinos. For the first time, transitions of $^{214}$Pb to both the ground and excited states of $^{214}$Bi are measured concurrently, revealing discrepancies in branching ratios of up to 4.7$\sigma$ relative to previous evaluations. Combined with state-of-the-art theoretical spectral shape calculations, these results establish a new benchmark for background modeling in rare-event searches and highlight the potential of tracking spectroscopy as a versatile tool for fundamental physics and nuclear applications.

By critically evaluating higher-order nonlinear effects to the isotope shifts (ISs) in the low-lying transition frequencies of the singly charged calcium ion, stringent constraint on the electron-neutron coupling due to a hypothetical boson describing physics beyond the Standard Model is inferred. It shows an order magnitude difference compared to the previously reported limit demonstrating importance of higher-order effects in the analysis of nonlinearity in the King's plot. The first-order IS parameters and enhancement factor ($D$) were evaluated using two complementary approaches in the relativistic coupled-cluster theory framework: namely finite-field (FF) and analytical response (AR) approaches. Extraction of the second-order IS parameters in the FF approach show numerical instabilities, so they are determined in the AR approach. Comparison of these factors with previous calculation shows substantial differences in the magnitudes. However, $D$ values from both the FF and AR approaches display excellent agreement. We also show explicitly roles of electron correlation effects in the evaluation of $D$ values accurately.

Entanglement is a fundamental resource in quantum information science, with profound implications for computing, communication, and metrology. Nuclear scattering processes, dominated by rich spin-dependent interactions, offer a natural platform for generating complex spin entanglement. Here, using proton-proton scattering as a quantum laboratory, we report the emergence of a near-pure Bell-triplet state at a laboratory energy of 151 MeV and a center-of-mass scattering angle of 90 degrees, with the spin amplitude a transition operator connecting two different Bell states. In contrast to the low-energy singlet state governed by the Pauli principle and the S-wave dominance, this second maximally entangled state is directly shaped by tensor forces beyond leading-order chiral effective field theory, providing a distinct quantum-information signature for realistic nuclear forces. These findings, invisible to traditional scattering observables, establish proton-proton scattering as a robust source of triplet entanglement and pave the way for next-generation nuclear Bell tests.

The profile of the pion valence quark distribution function (DF) remains controversial. Working from the concepts of QCD effective charges and generalised parton distributions, we show that since the pion elastic electromagnetic form factor is well approximated by a monopole, then, at large light-front momentum fraction, the pion valence quark DF is a convex function described by a large-$x$ power law that is practically consistent with expectations based on quantum chromodynamics.

Accurate separation of signal from background is one of the main challenges for precision measurements across high-energy and nuclear physics. Conventional supervised learning methods are insufficient here because the required paired signal and background examples are impossible to acquire in real experiments. Here, we introduce an unsupervised unpaired image-to-image translation neural network that learns to separate the signal and background from the input experimental data using cycle-consistency principles. We demonstrate the efficacy of this approach using images composed of simulated calorimeter data from the sPHENIX experiment, where physics signals (jets) are immersed in the extremely dense and fluctuating heavy-ion collision environment. Our method outperforms conventional subtraction algorithms in fidelity and overcomes the limitations of supervised methods. Furthermore, we evaluated the model's robustness in an out-of-distribution test scenario designed to emulate modified jets as in real experimental data. The model, trained on a simpler dataset, maintained its high fidelity on a more realistic, highly modified jet signal. This work represents the first use of unsupervised unpaired generative models for full detector jet background subtraction and offers a path for novel applications in real experimental data, enabling high-precision analyses across a wide range of imaging-based experiments.