Papers

We investigate the structure of the $K^+$ meson through calculating its valence-quark (anti quark) generalized parton distribution functions (GPDs) and form factors (FFs). For this purpose, we use a theoretical framework which is based on the exponential representation scheme (ERS). In this scheme the valence-quark GPDs of the light mesons, including the kaon, are considered as the valence quark distribution function crossed by the exponential of a profile function, at zero skewness. We apply the modified chiral quark model ($\chi QM$ ) to obtain the input valence distribution functions of the kaon in above scheme and calculate its valence GPDs. The kaon's electromagnetic and gravitational form factors are also determined and compared with existing experimental data and the results of some theoretical and phenomenological models.

Statistical inference is a crucial part of HEP analyses. Historically based on RooFit and RooStats, the statistical tools used by the experiments are now facing unprecedented challenges, such as the rapidly growing complexity of statistical models (involving hundreds of parameters of interest and thousands of nuisance parameters), the need for scalable performance in large likelihood minimizations, and the demand for interoperability across an increasingly diverse ecosystem of tools, computational hardware, and frameworks and libraries, especially the ones developed and used within the machine learning world. This contribution summarizes status and future plans for the statistical tools used by some of the main LHC experiments (CMS, ATLAS), with a focus on improvements coming from the ROOT world (RooFit automatic differentiation), interoperability with modern libraries (JAX) and communication across frameworks (HS3).

The Analysis Grand Challenge (AGC) showcases an example of HEP analysis. Its reference implementation uses modern Python packages to realize the main steps, from data access to statistical model building and fitting. The packages used for data handling and processing (coffea, uproot, awkward-array) have recently undergone a series of performance optimizations. While not being part of the HEP Python (PyHEP) ecosystem, the Combine tool is a pillar of CMS analyses, covering more than 90% of the analyses published in the last few years. As such, it is necessary to have Combine integrated in the PyHEP ecosystem, using the AGC as example. This project also includes, in the long-term, providing support and integration for the High Energy Physics Statistics Serialization Standard (HS3), as a way to have a language-independent way of representing the likelihood and use different frameworks interchangeably. In these proceedings we cover part of the recent work performed on the AGC and Combine, including: performance benchmarks, covering benefits introduced by the recent improvements in the data processing packages; examples of how Combine can be integrated and run in a dedicated infrastructure (coffea-casa); and examples and plans to integrate HS3 in Combine.

We carry out a unified study of the low-lying $1S$-wave compact states and hadronic molecules composed of hidden charm pentaquarks $qqqc\bar{c}$ ($q=u,d$) within a semirelativistic potential quark model. Apart from the linear confinement and one-gluon exchange potential between quarks and/or antiquarks, one-boson exchange potential is also included for baryon and meson clusters within the pentaquark system. We also evaluate the fall-apart decays by combining the obtained spectra within the quark exchange model. It is found that the $P_c (4312)^+$, $P_c (4440)^+$, and $P_c (4457)^+$ observed by the LHCb Collaboration in 2019 can be well explained by the hadronic molecules of $[\Sigma_c\bar{D}]_{1/2^-}^{1/2}(4318)$, $[\Sigma_c\bar{D}^*]_{1/2^-}^{1/2}(4437)$, and $[\Sigma_c\bar{D}^*]_{3/2^-}^{1/2}(4458)$, respectively. Meanwhile, $P_c(4380)^+$ reported by LHCb in 2015 may be assigned as the molecule $[\Sigma_c^*\bar{D}]_{3/2^-}^{1/2}(4382)$, except that it turns to be a narrow state other than a broad one shown by the experimental data. Our study shows that the $\sigma$- and $\rho$-meson exchanges are crucial for the formation of $\Sigma_c^{(*)}\bar{D}^{(*)}$ bound states with isospin $I=1/2$. Depending on the potential strength of the $\sigma$ exchange, there may exist very shallow bound states of $\Lambda_c\bar{D}^{(*)}$ with isospin $I=1/2$ and $\Sigma_c^{(*)}\bar{D}^{(*)}$ with isospin $I=3/2$. Our study may provide useful information for further exploring the hidden-charm pentaquarks in future experiments.

Three-dimensional fine-grained plastic scintillator detectors are extensively used in high-energy physics experiments where particle tracking, identification, calorimetry and sub-nanosecond timing information are required. Moreover, the low cost of plastic scintillator makes, in principle, the scalability to multi-tonne detectors possible. In order to circumvent the difficulties related to the long production time and the challenging assembly of millions of tiny independent scintillating voxels, a new technology consisting of gluing a few thousand $9 \times 9 \times 9$ mm$^3$ plastic scintillator cubes in a single large monolithic layer with machining precision, while ensuring an efficient optical separation, was developed and demonstrated. In this work we demonstrate that such technology can be reliably extended to a monolithic layer of $48 \times 48$ optically-isolated scintillating cubes, the size required for future ton-scale detectors, fulfilling the requirements of future neutrino detectors and sampling calorimeters.

The long-standing upward shift of the extracted $\psi(4160)$ mass, from about $4.16$~GeV to $4.19$~GeV in later analyses, remains a puzzling issue in charmonium spectroscopy. In our previous study, this problem was investigated through the $B^+\to K^+\mu^+\mu^-$ process within an unquenched charmonium framework, where the lower-mass $\psi(4160)$ assignment was found to be compatible with the data. Here we revisit the BESII $R$-value data, which played an important role in the historical extraction of the higher $\psi(4160)$ mass, and provide an independent examination. In contrast to the conventional quenched picture with $\psi(4040)$, $\psi(4160)$, and $\psi(4415)$, the unquenched vector-charmonium spectrum contains six states: $\psi(4040)$, $\psi(4160)$, $\psi(4220)$, $\psi(4380)$, $\psi(4415)$, and $\psi(4500)$. Including these states together with the near-threshold $\psi(3770)$, we find that the BESII $R$-value line shape can be well reproduced over the full energy range while retaining the lower-mass $\psi(4160)$ assignment. The enhancement around $4.19$~GeV then arises from the coherent interplay among the nearby $\psi(4040)$, $\psi(4160)$, and $\psi(4220)$ amplitudes, rather than requiring an upward shift of the $\psi(4160)$ mass itself. The additional higher states also naturally describe the line-shape structure in the $4.4$~GeV region. We further show that the seven-resonance coherent amplitude contains six complex zeros, yielding $2^6=64$ mathematically equivalent solutions with identical line shapes but substantially different di-electron widths and relative phases. Comparing these solutions with available experimental information and representative unquenched charmonium predictions, we provide a qualitative assessment of their phenomenological consistency and highlight several solutions that appear more compatible with present information.

Experimental particle physics collaborations staff their detectors around the clock with members drawn from dozens of institutions. The established practice is a credit system with self-sign-up: institutions owe a quota of credit, and people take the seats they want when booking opens. This paper describes a method in which seats are instead allocated from ranked wishes under institutional quotas, the result is issued as offers that each person accepts or declines, and an independent checker recomputes every rule before anything is published: the platform proposes, never assigns, and proves that it kept the rules. The credit and quota model is inherited from current practice. Around that core the paper adds a quota rule that keeps indivisible blocks fair to institutions whose share of a period is smaller than one block, and four rules that make fairness visible beyond the count: shares of owl, weekend and holiday blocks, seats shown in the laboratory's clock and the institution's own, reachable pools for institutions that cannot travel, and booking order by balance. On a synthetic collaboration of 48 institutions and 256 eligible members, the method allocates 70 to 72 of 72 seats per period in two rounds, with a mean rank satisfaction of 84 to 95% and no rule broken; after a year of running every institution of four members or more is within 13% of its cumulative share, and the smallest institutions, which one block overshoots by arithmetic, are brought within the same range by pooling in pairs. The method is stated completely enough to be reimplemented; a reference implementation exists and is available to collaborations under license. It applies as it stands to any scientific collaboration that staffs a facility in blocks of shifts under institutional quotas.

Higher twists in deep-inelastic scattering (DIS) and related hard scattering processes provide a unique window on nonperturbative QCD dynamics, encoding quark-gluon correlations and multiparton interactions beyond the leading-twist parton model. We present an overview of the theoretical foundations of higher twists in QCD, based on the operator product expansion, and discuss their intimate connection with quark-hadron duality in the transition between the resonance and scaling regimes. We review the phenomenology of higher-twist effects in unpolarized and polarized DIS, emphasizing their extraction from precision data through modern global QCD analyses that simultaneously determine both leading-twist parton distribution functions and higher-twist contributions. Finally, we discuss recent developments in the study of higher twists in semi-inclusive and exclusive reactions, and conclude by highlighting future opportunities to study QCD dynamics beyond leading twist at Jefferson Lab and the Electron-Ion Collider that promise to deepen our understanding of hadron structure.

We study T-odd effects through two-photon exchange in semi-inclusive deeply inelastic scattering in the kinematic region where the produced hadron has a low transverse momentum. The absorptive part of lepton-quark scattering amplitude is calculated. Transverse momentum dependent factorization is performed with the absorptive part. Although the absorptive part is divergent, the physical results, i.e., the obtained differential cross-section, is finite. Including the T-odd effects, the differential cross section receives new contributions which have different angular dependence than that obtained with one-photon exchange. Certain asymmetries can be introduced to detect the T-odd effects. Our results here are not only relevant to detecting new effect beyond the one-photon approximation in the process but also relevant to searching for new physics at lepton-proton colliders.

Over the past three decades, generalized parton distributions (GPDs) have emerged as one of the most active and important areas of research in nucleon structure and quantum chromodynamics (QCD). Since the last comprehensive review two decades ago, substantial progress has been made in experimental measurements of hard exclusive processes, such as deeply virtual Compton scattering and near-threshold $J/\psi$ production, as well as in increasingly sophisticated phenomenological analyses of GPDs that enable three-dimensional nucleon tomography. Theoretical advances in perturbative coefficient functions, scale evolutions, and kinematic and power corrections have considerably improved the precision of GPD phenomenology, while new hard exclusive processes for probing GPDs have been explored. More interestingly, lattice QCD can now directly access GPDs at fixed parton momentum fractions $x$ and skewness $\xi$ through large-momentum expansions, in addition to the traditional calculations of their moments, or generalized form factors. Significant progress has also been made in exploring the QCD energy-momentum tensor that encodes fundamental information on the nucleon's mass distribution, complete spin structure, and spatial distributions of momentum current and color-Lorentz forces acting on quarks and gluons.

The upcoming SHiP experiment may probe interaction strengths of decaying feebly coupled particles several orders of magnitude below existing limits. In the event of a discovery, it may also reveal the nature of the new particle. This requires identifying its exact production mechanism, which SHiP does not observe directly. We explore whether this mechanism can be inferred from the kinematics of its visible decays. As a benchmark, we consider an axion-like particle (ALP) with a dominant diphoton decay, which may occur for couplings to the $U(1)_Y$ and $SU(2)_L$ gauge fields. For a known ALP mass, the observed energy and angular distributions depend on the relative magnitude and sign of the couplings and on the unknown lifetime, which we profile independently under each hypothesis. We first determine how the ALP energy and its longitudinal and transverse decay positions distinguish the interactions, assuming perfect reconstruction and accounting for production, propagation, decay, and geometric acceptance. We then include the detector response and reconstruct the diphoton decays using a full simulation of the SHiP electromagnetic calorimeter. Only $2$–$4$ reconstructed diphoton events are needed to distinguish the two pure $U(1)_{Y}$ and $SU(2)_{L}$ interactions for ALP masses between $0.2$ and $1~\mathrm{GeV}$. For coupling admixtures, the study assuming perfect reconstruction indicates requirements of several tens to $\mathcal{O}(10^2)$ events in favorable regions.

Should the Higgs boson be found to couple to a hidden dark sector, it will become necessary to determine the nature of the Higgs portal responsible. Could the minimal, marginal Higgs portal operator be distinguished from a Higgs portal interaction involving a higher-dimensional operator? This is unlikely for Higgs portals with on-shell invisible decays to light dark sectors, but for an off-shell Higgs portal above threshold, where the dark sector is too heavy to contribute to the invisible Higgs decay width, we find that the higher-dimensional Higgs portal operators could in principle be differentiated by combining measurements across the integrated programme of HL-LHC, FCC-ee, and FCC-hh. This illustrates the complementarity of precision and high-energy exploration to phenomenologically profile Higgs portal interactions and probe possible connections between the electroweak scale and a hidden universe.

In particle collider experiments, event reconstruction is the task of inferring the kinematics of short-lived particles produced in the hard scatter from the stable final states recorded by detectors. We decompose event reconstruction into two primary tasks: assigning measured jets and charged leptons to parent particles, and predicting unmeasured neutrino kinematics. We present VyPER, a novel geometric learning framework that represents collider events as hypergraphs with a physics-inspired topology. VyPER combines the supervised classification of hyperedges for particle assignment with a diffusion model for predicting neutrino kinematics, leveraging a joint loss function to optimize both reconstruction tasks within a unified framework. We showcase VyPER across several proton-proton collision processes, comparing its performance to existing analytical and machine-learning-based reconstruction techniques. In doing so, we demonstrate that accurate event reconstruction is achievable across a diverse range of Standard Model physics processes, opening new avenues for precision measurements in the Higgs boson, electroweak, and top-quark sectors.

Motivated by the recent CMS data on a family of $2^{++}$ states from $J/\psi J/\psi$ mass spectrum, we determine the masses of the $2^{++}$ $J/\psi J/\psi$ molecule and $cc\bar c\bar c$ states, by using (for the first time) the two lowest QCD Laplace Sum Rules (LSR) moment-ratios within the standard optimization criteria with respect to the LSR variable $\tau$ and to the QCD continuum threshold $t_c$ implemented by the $R_{P/C}$ requirement that the lowest ground state (Pole) contribution to the LSR is larger than the QCD continuum one. Including factorized NLO perturbative and LO $G^4$ gluon condensates in the OPE, we obtain the the lowest ground state masses: $M^{2^{++}}_{J/\psi J/\psi}=6521(69)$ MeV and $M^{2^{++}}_{cc\bar c \bar c}=6347(99)$ MeV with the couplings\,: $f^{2^{++}}_{J/\psi J/\psi}=96(14)$ keV and $f^{2^{++}}_{cc\bar c \bar c}= 151(29)$ keV normalized as $f_\pi=93$ MeV. The masses of the first radial excitations are :$M^{2^{++}{rad}}_{J/\psi J/\psi}=7987(251 )$ MeV and $M^{2^{++}{rad}}_{cc\bar c \bar c}=7739(221)$ MeV indicating a mass-splitting about $2.5 (M_{\psi(2S)}-M_{J/\psi})$. The decay constants are $f^{2^{++}{rad}}_{J/\psi J/\psi}=248(70)$ keV and: $f^{2^{++}{\rm rad}}_{cc\bar c\bar c}=453(96) $ keV which are (unexpectedly) larger than the lowest ground state ones. These features may indicate some new dynamics compared to ordinary $\bar cc$ states. We extend the analysis to the $0^{++}$ states and to the $\Upsilon\Upsilon$ family where the results are compiled in Tables 2 and 3. We critically review some other QCD spectral sum rules (QSSR) results. We suggest that the X(6600) might be a molecule ground state. Using a two-component mass mixing scheme, the X(6900) and X(7100) might be interpreted as a mixture of the $cc\bar c\bar c$ lowest ground state with its 1st radial excitation via an angle $\theta=5^0$.

Tau spin correlations at the $Z$ pole probe CP violation with a sensitivity that depends strongly on the spin projection. For a fixed $Z$ sample, transverse moments avoid the chirality suppression of longitudinal and triple-product observables, enhancing the response by a factor $m_Z/2m_\tau=26$. Two transverse moments also select the axial tau charge, gaining $|a_\tau/v_\tau|=13.5$; the sign-weighted normal moment has a response $521$ times that of the triple product. These two transverse moments give single-parameter uncertainties no more than $14\%$ above our calculated Cramer-Rao bound for independent single-pion measurements, approaching the best precision within this analysis. A five-moment fit with $5\%$ off-peak luminosity yields statistical uncertainties of $4.5 (5.5)\times10^{-7}$ and $2.7 (3.2)\times10^{-6}$ on $\operatorname{Re}\widetilde{d}_\tau^W$ and $\operatorname{Im}\widetilde{d}_\tau^W$, respectively, at FCC-ee (CEPC), improving on ALEPH by three orders of magnitude. The electromagnetic-dipole uncertainty is $9.6 (12)\times10^{-6}$ on $\operatorname{Re}\widetilde{d}_\tau^\gamma$, two orders beyond Belle. These projections assume ideal angular reconstruction and constant form factors across the scan.

We present a complete calculation of the next-to-leading order (NLO) electroweak corrections to the loop-induced gluon-fusion process $gg\to\gamma\gamma$ at the LHC, including the full third-generation quark and the Higgs boson contributions for the first time. To efficiently evaluate the large number of multi-scale two-loop Feynman integrals, we employ a numerical approach based on differential equations with an optimized basis. Our results show that, although the NLO electroweak corrections to the phase-space-integrated cross section remain at the sub-percent level, they can reach about $-10\%$ in the tails of the diphoton invariant-mass and photon transverse-momentum distributions. Moreover, the diphoton invariant-mass distribution exhibits rich and intriguing structures, including a dip-bump structure in the Higgs-threshold region and a mild enhancement near the top-quark pair threshold. These features make the electroweak corrections indispensable for future precision studies of diphoton production at the LHC.

For sixty years, the Sun served neutrino physics more than the reverse: its neutrinos established oscillations rather than probing the star itself. That is now changing. Reactor antineutrinos have pinned down the oscillation parameters governing solar-neutrino flavour conversion so precisely that the propagation-related uncertainty is becoming negligible – closing the first of two abysses. Solar neutrinos can, at last, be turned on the Sun. Yet a second abyss remains: today's solar-neutrino detection falls an order of magnitude short of the precision the Standard Solar Model already predicts for the dominant pp flux ($>\,$90$\%$) – a gap no reactor experiment can close. The intrinsic $^{14}\mathrm{C}$ background walls off the pp region; only new detection techniques can breach it. Bridging this second abyss demands a revolution, not an increment. Combined with helioseismology's complementary reading of the Sun's mechanical structure, precision neutrino measurements of the nuclear source terms would enable a multi-messenger heliotomography of the solar interior – reading our star from both sides at once. A new age of solar discoveries may follow, on one condition: that the field builds the instruments equal to the task.

Relativistic nuclear collisions have opened an experimental arena for studying many-body correlations in nuclear ground states. However, the connection between initial-state correlations and final-state multi-particle observables measured at colliders is not yet formulated as a systematically improvable matching problem. We show that detector correlators built from asymptotic energy flows provide a natural framework for realizing such a construction. In particular, we express the asymptotic energy flow as a functional of the early-time stress tensor, and expand it in suitable modes to recover the familiar linear hydrodynamic relations at leading order. Then, motivated by small-$x$ QCD, we map angular projections of detector correlators to multipole-operator correlators computed in the colliding nuclei. We thus establish a systematic formalism for matching long-wavelength correlations between incoming and outgoing QCD states in high-energy hadronic collisions.

The 2025-2026 update of the European Strategy for Particle Physics placed renewed emphasis on quantitatively robust comparisons between future collider projects. Within this context, the Electroweak physics working group of the Physics Preparatory Group (PPG EW WG) carried out a comprehensive assessment of the projected sensitivities of different facilities to Higgs boson, electroweak and top-quark observables, with particular attention on different scenarios of theoretical uncertainties. These studies are summarized in the Physics Briefing Book. The aim of this document is to (a) provide a more detailed account of the evaluation of theoretical uncertainties, which was undertaken within the PPG EW WG, and (b) document the collider-specific inputs used in the electroweak and Standard Model effective field theory (SMEFT) fits and discuss any needed modifications in order to harmonize assumptions between projects. In presenting the detailed theoretical uncertainty treatment and the explicit collider inputs and assumptions, this work aims to improve the reproducibility and future extensibility of the results presented in the Physics Briefing Book.

We study the sensitivity of the proposed DarkSHINE experiment to displaced dark photon decays, $A'\to e^+e^-$, using an 8~GeV electron beam incident on a tungsten target. We consider $2m_e<m_{A'}<2m_\mu$ and assume a unit branching fraction to electron–positron pairs. Signal events generated at tree level with CalcHEP are propagated through a detailed Geant4 detector simulation. A close tracker, graph-neural-network-based track reconstruction, and displaced vertex selections suppress prompt pair-production and photon-conversion backgrounds, while calorimeter and invariant-mass requirements render hadronic backgrounds negligible. Extrapolation of the residual prompt-background distribution yields 0.3 expected events for $9\times10^{14}$ electrons on target. The median expected 90% confidence-level exclusion covers masses of approximately 30–70~MeV and kinetic mixing parameters from approximately $5\times10^{-5}$ to $2\times10^{-4}$. This visible decay search complements DarkSHINE searches for invisible dark photon decays.

We report Geant4-based simulations of cosmic-ray muon backgrounds in models reproducing the geometries of the five-arm and six-arm e+e- pair spectrometers operated by the Atomki group at Debrecen. Full detector geometries are implemented for both setups, including position-sensitive detectors and plastic scintillators. In both configurations, cosmic muons generating two-arm coincidences produce statistically significant excesses in the opening-angle distribution whose positions are determined by the discrete azimuthal arrangement of detector arms and the plastic scintillators dimensions: in the six-arm spectrometer a peak appears near 140 degrees when the scintillator energy sum is selected in the 8Be transition window (16-20 MeV) and is suppressed for energy-asymmetric pairs, while a distinct peak near 120 degrees emerges in the 4He window (18-22 MeV), with no comparable enhancement in the respective background energy region. These angles, asymmetry dependences, and background characteristics show behaviours similar to those reported by the Atomki group as evidence for a 17 MeV boson. For the five-arm setup, a 140-degree excess is also reproduced at 8Be energies, and normalizing internal pair conversion events and cosmic coincidences to typical Atomki running conditions yields a cosmic-to-IPC ratio above unity in the signal window, indicating that the cosmic background is a leading contribution to the event rate at the energies and angles of interest. While they do not settle the question of the origin of the Atomki excesses, these results highlight the critical importance of a robust cosmic-ray treatment in this type of measurements, and call for a detailed description of the beam-off studies supporting the search for anomalies in the opening-angle vs. energy-sum distribution around the signal region.

High-energy hadron reactions could be appropriate to find exotic evidences in exotic hadron candidates instead of global observables such as masses, spins, parities, and decay widths, because quarks and gluons are explicit degrees of freedom. One of possible methods is to use fragmentation functions (FFs) by taking advantage of properties on favored and disfavored functions, which corresponds to valence-quark and sea-quark distributions in parton distribution functions. Looking at these FFs, we should be able to find the exotic nature as the valence-quark distributions reflect the nature of valence constituents as shown in the pion and the proton. Recent accurate measurements of the $f_0$(980) FFs by the Belle collaboration made it possible to find its internal configuration by looking at their second moments and functional forms. Global analysis results of the $f_0$(980) FFs indicate that its internal configuration looks like $s\bar s$, which is different from a tetraquark or $K\bar K$-molecule like configuration suggested from low-energy studies. This fact indicates that the internal configuration looks different depending on the energy. At low energies, it looks like a tetraquark ($K\bar K$ molecule) hadron, but it looks like a $q\bar q$ hadron at high energies. In the similar way, some exotic hadron candidates could become ordinary $q\bar q$ or $qqq$ hadrons at high energies, although they are interpreted as exotic at low energies. This kind of new idea should be tested by future experiments especially by looking at energy or momentum dependencies in high energy hadron reactions.

In lepton scattering from nuclei, it has been taken for granted that nuclear modifications do not exist for the longitudinal-transverse structure-function ratio $R$, although nuclear effects in $F_2$ have been investigated for a long time. In fact, experimental data of lepton-nucleus scattering have been analyzed with this assumption. It is obviously not appropriate because nuclear modifications exist in the function $R$ theoretically as shown in this work. In this work, we explain nucleon's Fermi motion's effects by using a convolution description for nuclear structure functions, especially on the deuteron. The longitudinal and transverse structure functions are defined by taking the virtual photon momentum direction along the $z$ axis. However, nucleons in a nucleus could move in any direction, so that nucleon's longitudinal and transverse structure functions could mix with each other in the nuclear medium. Such mixing effects could be of the order of $\vec p_\perp^{\,2}/Q^2$, where $\vec p_\perp$ is the nucleon's transverse momentum and $Q^2$ is given by $Q^2=-q^2$ with the virtual-photon momentum $q$, because the transverse Fermi-motion is the source of such a mixture. In addition, nuclear effects are different between the longitudinal and transverse structure functions in the convolution model because their $x$-dependent functional forms are different. Convolution integrals have different results between the longitudinal and transverse structure functions for nuclei. Because the experiment is in progress at the Thomas Jefferson National Accelerator Facility to measure the function $R$ for the deuteron, the numerical results are shown on the nuclear effects of $R$ in the deuteron. Hopefully, such nuclear effects are found experimentally by future experiments including heavy nuclear targets.

Inspired by the recent observation of the $\Sigma_c(3200)^0$ baryon in the $\Lambda_c^+\pi^-$ invariant mass spectrum by the LHCb Collaboration, we perform a comprehensive investigation of the $D^{(*)}\Delta$ interactions within the one-boson-exchange framework. Our results show that the $D^*\Delta$ molecule with $I(J^P)=1(1/2^-)$ can be regarded as the most natural candidate for the $\Sigma_c(3200)$, and predict the existence of several $D^*\Delta$ molecular partners with $I(J^P)=1(3/2^-, 5/2^-)$ and $2(1/2^{\pm}, 3/2^{\pm}, 5/2^-)$. After including the coupled channel effects between $D\Delta$ and $D^*\Delta$, several shallowly bound $D\Delta$-dominated molecular candidates also emerge, especially for the $I(J^P)=1,2(3/2^-)$ and the $2(1/2^+,3/2^+)$ systems. These results provide a unified molecular interpretation of the newly observed $\Sigma_c(3200)^0$ and useful guidance for future experimental searches for exotic charmed-baryon states. We expect the high-statistics data from the LHCb Upgrade and Belle~II runs will directly test these predictions.

We consider the dominant production mechanism of bottom-flavoured jets at the LHC, which proceeds through bottom-quark pair production. We compute next-to-next-to- leading-order (NNLO) QCD corrections retaining full bottom-quark mass effects and match them with a parton shower (NNLO+PS). Our predictions provide a realistic description of events with one and two bottom-flavoured jets at both the partonic and hadronic level. We compare different jet-flavour definitions and confirm that the dominant numerical differences between the jet algorithms result from the treatment of jets that contain two bottom quarks originating from $g\to b\bar b$ splittings. We compare our predictions, using the experimental bottom-flavour tagging prescription, with measurements by ATLAS, CMS, and LHCb at 7 and 13 TeV, finding good agreement for the distributions presented by ATLAS and CMS and a good description of the shapes of the LHCb data. We also discuss the impact of various physics effects on the considered distributions: power corrections in the bottom-quark mass, the implications of symmetric/asymmetric jet-selection cuts, as well as contributions from multi-parton interactions.

A species-resolved anisotropy-response scaling framework is used to investigate the structure and formation dynamics of the $f_0(980)$ in relativistic nuclear collisions. Published measurements in high-multiplicity p+Pb collisions at $\sqrt{s_{NN}}=8.16$~TeV exhibit broad scaling closure under a single-meson response construction, with a small effective final-state response, $\zeta_{f_0}\simeq0.04$, whereas a symmetric ${\rm K\bar K}$ constituent-response construction gives substantially poorer closure. An explicitly molecular ${\rm K\bar K}$ calculation also exhibits single-meson-like scaling but gives a substantially larger effective final-state response, $\zeta_{f_0}\simeq0.16$. Thus, single-meson scaling alone is not a unique structural discriminator. The combined response construction and $\zeta_{f_0}$ constraints characterize the measured $f_0(980)$ by a single-meson-like anisotropy response with weak final-state sensitivity, distinctly different from the molecular benchmark. These results establish anisotropy-response scaling as a new experimental probe of $f_0(980)$ formation dynamics and motivate systematic tests across collision systems and beam energies.

Many self-supervised methods for training foundation models at the Large Hadron Collider (LHC) rely on data augmentations to encourage the model to embed events into a representation space invariant to certain physical or detector symmetries. A common challenge arises from the large freedom in choosing a proper set of augmentations on which downstream performance depends. The implementation of augmentations involves either modifying existing events, potentially breaking the event fidelity, or simulating more event variants, which is computationally intensive. In this work, we present a data-driven method of pairing events by their similarity via the energy mover's distance (EMD), which measures how similar two events are in terms of the work required to transform one into the other. With this approach, distinct events are sampled and matched by their similarity to serve as views for learning invariance, keeping the physics content of each event intact without handcrafted distortions. We demonstrate this augmentation-free pairing method by pre-training on QCD jets via self-distillation and show that it can yield semantic jet embeddings with downstream discrimination power comparable to or better than an augmentation-based baseline.

Reconstructing the mass of a heavy resonance from its decay products with missing energy is one of the central tasks that directly determine the sensitivity in new physics searches at collider experiments. Supervised learning approaches to this problem often struggle to generalize well due to the presence of various systematic uncertainties and distribution shifts. Exhausting all possible variations in the labeled data can be very compute-intensive, while a failure of the model to generalize can corrupt the reconstructed resonance widths that are critical in peak-hunting analyses. In this work, following the foundation model paradigm, we use a self-supervised approach to pre-train a transformer encoder with VICReg to learn an embedding invariant to various corruptions, then fine-tune it for mass regression on a heavy resonance with masses ranging from 2.5 to 6.5 TeV and a SUSY-like cascade decay into an eleven-body final state. We show that the pre-trained model reconstructs sharper resonance peaks and has a more stable performance under various realistic corruptions, compared to a supervised model of the same architecture trained on the same augmented data from scratch.

Weakly interacting massive particles (WIMPs) constitute one of the best-motivated dark matter (DM) candidates. In this study, we consider a simple extension of the WIMP paradigm in which WIMPs are coupled to a heavier particle that interacts only with them and can decay into WIMPs. In the early Universe, when WIMPs are in thermal equilibrium with the Standard Model (SM) bath, they serve as a portal to populate the heavy partner through inverse decays. Depending on the lifetime of the partner particle, its eventual decay into WIMPs can significantly alter the WIMP abundance. If the partner decays into WIMPs before their freeze-out from equilibrium, the standard thermal history remains unchanged. When the decay occurs after WIMP freeze-out, however, the injected non-thermal population of WIMPs can result in an overproduction of DM, therefore requiring a larger WIMP annihilation cross section relative to the standard scenario without the partner. For a given partner lifetime and WIMP annihilation cross section, freeze-out may be delayed due to re-annihilation or followed by a freeze-in phase. By solving the Boltzmann equations both semi-analytically and numerically, we explore these thermal histories and study the required enhancement in the WIMP annihilation cross section compared to the canonical value. This enhancement, which can reach up to three orders of magnitude, leads to stronger annihilation signals in the late Universe. As a result, current and upcoming indirect detection experiments are able to probe the lifetime of the partner particle. We briefly explore possible connections between our scenario and the baryon asymmetry of the Universe. As an example, we show that the Next-to-Minimal Supersymmetric Standard Model (NMSSM) can provide a realization of our scenario, with the possibility of accommodating light higgsino DM with the correct relic abundance.

Weakly supervised anomaly detection has been shown to be an effective tool for model-agnostic searches for new physics, especially in the context of resonance searches. However, correlations between the anomaly score and the resonant mass can distort the background distribution after selecting on the anomaly score, complicating background estimation from the sidebands. To mitigate this background sculpting, we propose a domain-adaptation-based decorrelation of the anomaly score from the resonant mass. We study this approach using the LHC Olympics R&D data set and several weakly supervised anomaly detection methods. We find that domain adaptation can substantially reduce background sculpting while largely preserving the anomaly detection performance. When correlations between the input features and the resonant mass degrade the original method's performance, domain adaptation can also recover sensitivity.