Papers

The Higgs vacuum expectation value (VEV) alters both the electroweak and strong interaction rates. We study both effects on Big Bang Nucleosynthesis (BBN) and seek concordance between observed primordial abundances of light elements and cosmological constraints from cosmic microwave background (CMB) fluctuations and anisotropies. We find a strong negative correlation between primordial 4He abundance and the Higgs VEV. Consequently, using a 1.58% uplift of the Higgs VEV during BBN from the current value, an agreement can be achieved among the new primordial 4He abundance, observed by the EMPRESS group, Deuterium abundance determined from absorption lines in the Lyman-alpha forest along the line-of-sight of high-redshift quasars, and the lithium abundance on the Spite plateau. This agreement requires a baryon-to-photon ratio different from the CMB determination, indicating the need for non-standard cosmological evolution between BBN and recombination epochs.We also demonstrate that a 0.2% uplift in the Higgs VEV can partially alleviate the "cosmic Li problem", keeping consistency with the CMB with remaining discrepancy potentially accounted for by stellar depletion mechanisms.

We propose Cat's Cradle diagrams as a framework to analyse the perturbative accuracy of gauge quantum field theories across different kinematic regions, interpolating between the power countings of fixed-order perturbation theory and soft-collinear resummation. We propose a simple intermediate counting aimed at quantifying parametric accuracy for resolved jet substructure, nested so that $N^nLO \subset N^nLJ \subset N^{n+1}LL$. We show that the resolved jet-substructure power counting, $N^nLJ$, emphasises contributions that are important for resolved substructure but which are lumped together with less dominant terms in both of the two other countings. It may therefore furnish a complementary quantification of relative parametric accuracy in a kinematic region "midway" between the hard (fixed-order) and soft-collinear (resummation) regimes. We discuss practical applications to parton showers, in the context of a hard process with a characteristic hard scale of order 200 GeV.

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.

The LUX-ZEPLIN experiment reported a candidate nuclear recoil at $248\,\mathrm{keV}$. This work proposes that endothermic self-scattering $\chi_1+\chi_1\to\chi_2+\chi_2$ in the Galaxy can produce an excited dark matter population, whose exothermic scattering $\chi_2+\mathrm{Xe}\to\chi_1+\mathrm{Xe}$ in xenon can account for the LZ candidate event. In a benchmark with a light scalar mediator, the conversion cross section is large enough for high-velocity Galactic dark matter particles to generate an excited fraction at the percent level. For dark matter masses near the TeV scale and mass splittings $\delta\gtrsim 500\,\mathrm{keV}$, the xenon recoil spectrum covers the candidate region and can yield an $\mathcal O(1)$ event count. The $\chi_2$ population produced in the Galaxy is colder than a relic population from the early Universe and yields a different nuclear recoil spectrum.

Primordial black hole dark matter is formed from the collapse of enhanced primordial density fluctuations. The formation of primordial black holes is accompanied by scalar induced gravitational waves whose infrared scaling only depends on the equation of state, $w$, of the background at leading order. Establishing whether this characteristic scaling remains robust under corrections of arbitrary perturbative order, including in the presence of non-Gaussianities, requires a physical understanding of the infrared scaling. In this work, we provide such a physical interpretation. We find that the stress of sound waves with nearly equal frequencies produces a slow beat. Although the incoming waves oscillate rapidly, this slow beat continues to source the long wavelength tensor perturbation before its horizon entry, thus generating an infrared scaling that only depends on the expanding background. We show that higher order interactions generate freely propagating waves that finally lead to the same slow beat deep inside the horizon. Since non-Gaussianities would not change the speed of the freely propagating waves, they do not modify the infrared scaling. As the source with a slow beat has enough time to accumulate before the horizon entry of the infrared tensor mode, it records the background expansion and thus the infrared scaling could provide a robust probe of the cosmological equation of state.

Effective infrared two-sheeted descriptions of fermion mixing between braneworlds have emerged in several distinct realizations and lead to testable matter-swapping effects, motivating low-energy searches and cosmological applications. The recurrence of the same low-energy fermion operator motivates asking whether this structure can also arise from a D-brane mechanism. We construct a local Type IIB D3$_+$-D7-D3$_-$/E3 realization in which direct interbrane mixing is perturbatively forbidden but generated non-perturbatively by a suitable E3 instanton sector. The resulting low-energy interaction reproduces the characteristic pseudoscalar structure of the two-sheeted fermion operator, together with its scalar companion, while D7 Wilson transport provides the required gauge-invariant relative connection. The construction therefore provides a local string realization of the same operator structure, subject to the stated instanton and zero-mode conditions. The analysis further provides a concrete model-building roadmap toward a compact phenomenological realization: the compactification must achieve electromagnetic sequestering of the two fermion sectors and support a sufficiently light non-uniform D7 gauge mode capable of mediating a long-range relative interaction. In such a complete compactification, the mixing parameter $g$ would in principle become computable from microscopic string data and directly testable against low-energy constraints.

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.

The detection of the Diffuse Supernova Neutrino Background (DSNB) is one of the main goals of the current and the next generation of neutrino experiments. Based on results published by the Super-Kamiokande (SK) collaboration, we study the sensitivity of current and future water Cherenkov detectors to the DSNB. We reproduce current constraints and estimate the sensitivity to the DSNB of ten years of SK data and of a next-generation water-Cherenkov detector like Hyper-Kamiokande (HK). We find that, even with increased exposure, SK's sensitivity is relatively modest, while HK has the potential to deliver a statistically significant discovery of the DSNB in ten years. Along the way, we perform a detailed study of the relevant atmospheric neutrino backgrounds and argue that an accurate treatment of neutrino oscillations and propagation is essential when it comes to properly inferring the sensitivity to the DSNB and measuring its flux.

In Seesaw Cosmology, a scalar field reheats the Standard Model (SM) through right-handed neutrinos (RHNs), which generate tiny neutrino masses through the seesaw mechanism. When RHNs rapidly fill a restricted momentum-space region, expansion continually opens new fermionic states that are refilled by subsequent scalar decays, maintaining an approximately constant physical RHN density. This gives rise to a novel heating regime in which the SM temperature increases with the scale factor as $T \propto a^{+3/8}$, in sharp contrast to the conventional $T \propto a^{-3/8}$ scaling during matter-dominated reheating.

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.

Pulsar timing arrays are a powerful tool for probing low-frequency gravitational phenomena and physics beyond the Standard Model. We establish a general, gauge-invariant framework for the timing residual by identifying the measurable quantity as the proper time interval between consecutive pulse arrivals at Earth. In linearized general relativity, we derive a general expression for this proper time shift and show that it decomposes into Doppler, Shapiro, and Einstein delay contributions whose sum is gauge invariant, similar to frameworks that have been developed for other gravitational-wave detectors such as laser and atom interferometers. We also provide a recipe for computing the resulting timing residual for any specified perturbation, and we illustrate the method with several physically well-motivated sources, recovering known results where they exist in the literature. This recipe can be directly applied to search for new physics from real pulsar timing data using existing numerical software.

Detector observables pose a fundamental challenge for nonperturbative lattice methods due to their intrinsically real-time and asymptotic nature. We propose quantum simulation platforms as an ideal setting for studying these observables. Using quantum spin systems as a demonstration, we construct lattice detector operators and establish their connection to continuum energy-flow observables. We demonstrate this framework in the $1+1$-dimensional quantum Ising model, where finite lattice calculations show quantitative agreement with conformal field theory expectations at criticality. These results support the interpretation of the lattice flow operators as regulated counterparts of continuum detectors in the scaling and asymptotic limits, providing a concrete route toward realizing high-energy collider physics on table-top quantum platforms.

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.

The vanilla scotogenic model (VSM) featuring three right-handed neutrinos and an inert scalar doublet, offers a unified explanation of neutrino masses, dark matter (DM), and the baryon asymmetry of the Universe through leptogenesis. The typical mass scale of such a scenario lies in the vicinity of $\sim$ 10 TeV and above, whereas enhanced second-generation Yukawa couplings lower the leptogenesis scale to $\sim 1$ \TeV, allowing the model to be probed at the future muon colliders. Adhering to DM, neutrino mass, Leptogenesis, and flavour dependent constraints, the charged scalar is likely to be a long-lived particle (LLP). We analyse both the prompt and displaced vertex signatures of the model to find that, prompt mono-photon signals remain challenging, but LLP searches offer a promising avenue to probe such a framework, subject to the timing resolutions, and displaced-vertex reconstruction efficiency.

The heavy-quark polarization in ultra-relativistic heavy-ion collisions (HICs) serves as a probe for unfolding the characteristics of deconfined QCD. The present study explores the spin alignment of $\mathrm{J/\psi}$ in the HICs by employing the rotational Brownian motion of charm quarks in the presence of a strong magnetic field. We derive an analytical expression for the polarization of the $c$-$\bar{c}$ pair based on the Fokker-Planck equation under the consideration of spin-vorticity coupling. These polarized $c$-$\bar{c}$ pairs lead to the formation of the $\mathrm{J}/\psi$ at the hadronization surface via the coalescence and fragmentation mechanisms. Correspondingly, we obtain the $m=0$ diagonal element $\rho_{00}$ of the $\mathrm{J}/\psi$ spin-density matrix, which quantifies its spin alignment along the chosen quantization axis. Our study provides a microscopic description of heavy-quark spin transport and suggests rotational diffusion as a possible mechanism underlying the observed $\mathrm{J}/\psi$ spin alignment.

Using perturbation theory for the fine-structure constant $\alpha$ and the electron-to-muon mass ratio, we calculated new contributions to the hyperfine structure of the ground state of the muon-electron helium atom. Compared to our previous results, we calculated new corrections in second-order perturbation theory. This calculation reduces the discrepancy between the theoretical value and the new experimental hyperfine structure measurement.

We investigate the relaxation of an approximately conserved charge in interacting quantum systems close to local equilibrium. To this end, we provide a pedagogical review of Zubarev's non-equilibrium statistical operator approach in the minimal setting of a single non-conserved charge and apply it to the problem at hand. We explicitly highlight the physical assumptions that lead to a local relaxation law: weak charge violation, a separation between the short timescale of microscopic correlations and the much longer timescale of charge relaxation, and the resulting loss of microscopic memory. Under these conditions, the leading relaxation rate is determined by an equilibrium correlation function of the charge-violating operator. We show that the same result follows from a simpler local-equilibrium construction based on the system's evolution over an intermediate timescale, providing a direct alternative for practical calculations and making the common physical ingredients of the two approaches explicit. Beyond the decay law itself, we relate the relaxation rate to the equilibrium diffusion of the same charge. We then allow the charge density to vary in space, which leads to a diffusion-relaxation equation. Finally, we illustrate the formalism through electroweak $\mathrm{B+L}$ washout and a perturbative scalar model, where agreement with the linearized Boltzmann equation establishes a direct connection between equilibrium-correlator and kinetic descriptions.

Recent measurements of the distribution of galaxies by the Dark Energy Spectroscopic Instrument (DESI) are in mild tension with a standard $\Lambda$-Cold Dark Matter cosmological model inferred from the anisotropies of the Cosmic Microwave Background (CMB) when extrapolated to low redshifts. Several solutions to explain this discrepancy in terms of new physics have been put forward, notably from new dynamics in a complex Dark Sector. Here we report on a resolution to this discrepancy that postulates that the inertial and gravitational masses of dark matter particles are not the same. Our best fit to CMB data combined either with Baryon Acoustic Oscillation (BAO) and Full Shape (FS) data from DESI DR1 (Data Release 1), or with BAO DR2 data alone, suggests the presence of a new long-range force in the Dark Sector with strength of $\beta \sim 0.5\% $ relative to gravity, at the $\sim 2.5\sigma$ level. A preliminary analysis combining FS DR1 and BAO DR2 data confirms the statistical power of DR2 and raises the evidence for dark forces to $\sim 3\sigma$, albeit ignoring the not yet available cross-correlation between the two datasets.

The recent high-recoil candidate event reported by LUX-ZEPLIN (LZ) motivates dark-matter scenarios with nonstandard kinematics and momentum-dependent interactions. We study a two-state inelastic dark-matter model in which $\chi_1$ and $\chi_2$ couple off-diagonally to an axion-like particle (ALP) that also couples to gluons and photons. Unlike treatments that assume only one dark-matter state is present today, we track the cosmological evolution of both states. The excited state $\chi_2$ is sufficiently long-lived to survive to the present, with its relic fraction determined by the dark-sector conversion process $\chi_2\chi_2\leftrightarrow\chi_1\chi_1$. We find that this fraction depends strongly on the Lorentz structure of the DM–ALP interaction: scalar transition couplings efficiently deplete $\chi_2$, favoring endothermic $\chi_1 N\to\chi_2 N$ scattering, whereas pseudoscalar transition couplings preserve $f_2\simeq1/2$, yielding recoil spectra dominated by exothermic $\chi_2 N\to\chi_1 N$ down-scattering. Benchmark spectra in all four scenarios can peak near the observed recoil energy of $250\,\mathrm{keV}$. Our results demonstrate that the dominant direction of inelastic scattering in direct detection can be dynamically selected by the early-Universe evolution of the dark sector. With additional data, annual modulation measurements could distinguish these scenarios. We further show that the ALP portal can be directly probed at colliders.

I present the first implementation in MadGraph5_aMC@NLO for bound-state production, including quarkonium, leptonium, and B(c) mesons within Non-Relativistic Quantum Chromo-Dynamics (NRQCD) and Non-Relativistic Quantum Electro-Dynamics (NRQED). In these proceedings, I focus on the extension of MadGraph5_aMC@NLO to quarkonium states and describe the capabilities of the new framework for inclusive and associated S-wave quarkonium production in a wide variety of experimental environments at Leading Order (LO). These developments provide the community with a unified, automated, and efficient framework for bound-state production in QED and QCD, and establish a solid foundation for our future Next-to-Leading-Order (NLO) extension.

We investigate net-baryon number fluctuations in the high-density, low-temperature region of the QCD phase diagram using the parity-doublet model (PDM) under the mean-field approximation. We compute the fluctuation ratios up to sixth order around the nuclear liquid-gas (LG) phase transition, where the high-order ratios are particularly sensitive. To connect the results with heavy-ion experiments, we test several different scenarios of chemical freeze-out. We find that near the LG transition the extracted fluctuations depend strongly on the choice of freeze-out curve. We self-consistently determine four freeze-out points from preliminary results of the STAR Collaboration. Comparing the experimental data with the PDM results along these four points, we find that the model describes the low energy ($\sqrt{s_{NN}}\lesssim$ 4 GeV) data well. This suggests that nucleon interactions and the LG phase transition may contribute significantly to the fluctuations in low energy heavy-ion collisions.

We use the proton spectrum resolved by LHAASO across the knee to test superheavy dark matter in the nucleon channel at PeV energies. Both the hardening at $0.34$ PeV and the knee at $3.3$ PeV are reproduced by nucleons from a relic of mass $5\cdot 10^{7}$ GeV decaying in the Galactic halo, with the mass as the only shape parameter of the spectrum and the background index profiled under an independent prior on the proton slope below $0.1$ PeV. It works equally well in all three hadronic-interaction-model reconstructions. On the other hand, the photons of the same cascade rule out this interpretation by about two orders of magnitude against the photon fraction of the cosmic radiation, and by about one order of magnitude against the LHAASO diffuse Galactic emission.

We present a complete calculation of the non-singlet splitting functions in four-loop quantum chromodynamics.

We discuss the phenomenological use of the next-to-leading order (NLO) eigenfunctions of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) kernel. We first recall the BFKL representation of high-energy scattering amplitudes and the role played by the eigenfunctions in the spectral representation of the Green's function. We then compare two equivalent representations of the next-to-leading logarithmic approximation (NLLA) amplitude, respectively based on the leading-order (LO) and NLO eigenfunctions. The two formulations are equivalent within NLLA, while differing by terms beyond this accuracy which could influence the phenomenological stability of high-energy observables. The aim is to test the possible role of NLO eigenfunctions-induced terms in improving this stability, discussing the amplitude dependence on the renormalization and energy scales. As an application, we consider first the forward electroproduction of two light vector mesons and then we comment on preliminary applications to Mueller-Navelet jet production.

Charge-dependent directed flow provides a sensitive probe of early electromagnetic fields and baryon stopping in relativistic heavy-ion collisions. Recent STAR measurements show a centrality-dependent sign change in the directed flow splitting (the difference between the directed flow of protons and antiprotons), indicating that electromagnetic effects alone are not sufficient to describe this observable and that the baryon stopping $-$ in particular the component of the stopped proton distribution that is odd in rapidity and odd under reflection in the impact parameter direction $-$ must also be included. We develop a semi-analytic hydrodynamic framework that combines spectator-induced electromagnetic fields with a Glauber-based description of baryon stopping, built upon an analytic solution for the background hydrodynamic flow due to Gubser together with the simplifying assumption of a constant electrical conductivity. For Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV, we find that baryon stopping gives a positive contribution to the directed flow splitting that decreases for more peripheral collisions, while electromagnetic fields give a negative contribution that is larger for more peripheral collisions. The competition between these two effects naturally reproduces the observed sign change in Au+Au collisions as a function of centrality, describes the observed rapidity dependence in the $50$–$80\%$ centrality interval, and reproduces trends seen in U+U collisions. Although the simplifying assumptions that we have made regarding the analytic background and constant conductivity limit our ability to make quantitative comparisons, our model provides a transparent explanation of how transported baryon number and spectator-induced electromagnetic fields jointly shape charge-dependent directed flow.

It is tantalizing to consider the recent observation of the LUX-ZEPLIN (LZ) experiment of a high energy nuclear recoil candidate at $E_{\rm Recoil} \simeq 248$ keV as the long-awaited signal of a weakly interacting massive Dark Matter (DM) particle. Although this signal is still weak and needs to be confirmed by further data and inspection, we attempt to interpret it in the context of the 2HD+a model in which a two-Higgs doublet model (2HDM) is supplemented by a light pseudoscalar Higgs boson $a$ and an isosinglet fermionic DM particle $\chi$. The model has the virtue of reproducing the correct cosmological density and evading the previous limits from direct and indirect detection of DM particles, while passing all constraints from colliders searches and high-precision measurements in the Higgs, electroweak boson and heavy-flavor sectors. We indeed find regions of the parameter space of the model, with a rather heavy 2HDM spectrum but a very light pseudoscalar $a$ boson, $m_a \approx 1-10$ GeV, as well as a DM fermion with a mass of a few hundred GeV, which are compatible with the LZ recoil event. The related extensive investigation of the parameter space of the 2HD+a model with fermionic DM, including the wide range of complementary constraints from both DM phenomenology and collider searches as well as precision measurements are presented.

Precise determination of the partonic structure of real photons has attracted renewed interest in view of ongoing studies of high-energy photon-induced processes in ultraperipheral collisions (UPCs) at the Large Hadron Collider (LHC) and the future Electron-Ion Collider (EIC). Despite being fundamental in their own right and essential for QCD phenomenology of hard processes initiated by resolved photons, the quark and gluon distributions of the photon are poorly known and merit a new analysis employing modern tools of statistical data analysis. We determine new sets of leading-order (LO) and next-to-leading-order (NLO) parton distributions (PDFs) for the real photon, dubbed VALO1.0, by performing a global QCD analysis of the world data on the photon structure function $F_2^{\gamma}$ measured in deep-inelastic scattering (DIS) processes on a real photon target in electron-positron collisions. Our analysis improves on the results available in the literature by providing uncertainties in the form of Monte Carlo replicas and the photon PDFs in the LHAPDF6 format. We observe that while the electron-positron data allow us to determine the singlet quark distribution very well at both LO and NLO, the gluon distribution is constrained to a much lesser degree, especially at LO. For this analysis, we have developed an open-source framework, which extends the pineline framework, developed for the proton, to the photon case and includes the program solving the inhomogeneous scale evolution of photon PDFs, $\gamma$EKO.

Liquid-argon TPC oscillation analyses increasingly split samples into proton-tagged (Np) and proton-less (0p) topologies at the ~35 MeV tracking threshold, but the standard GENIE Reweight library has no dial that transfers events across this boundary. We propose a single empirical nuisance parameter, $f_{\rm mig}$, that fills this gap as a per-event reweight on nominal GENIE output, implementable without event regeneration. It is presented as a methodological diagnostic: an effective topology-transfer surrogate absorbing an unspecified combination of near-threshold proton mismodelling effects (proton-side FSI, nucleon-momentum distribution, RES $Q^2$ shape, MEC kinematic shape), not a measurement of any single microscopic mechanism. As a reference scale, the position-dependent mean-field energy loss absent from GENIE's cascade is estimated from the $^{40}$Ar density profile to be a few percent, consistent with proton-transparency differences reported between cascade and transport generators on MicroBooNE data. The primary constraint is a direct scan on the MicroBooNE simultaneous CC 0p/Np differential cross-section release with no sector-weight regularisation: $\hat{f}_{\rm mig} = 0.093 \pm 0.024$, $3.8\sigma$ (Wilks) / $3.2\sigma$ (empirical). A supporting NC $\Delta$ radiative sideband fit gives $\hat{f}_{\rm mig} = 0.050^{+0.029}_{-0.022}$, conditional on sector-weight priors; the two datasets share flux/detector systematics and are corroborating rather than independent. Introducing $f_{\rm mig}$ also relieves a compensatory CCRES sector-weight suppression in migration-blind fits. The extracted parameter is best understood as a flux-integrated effective nuisance direction for the MicroBooNE BNB configuration, suitable as a candidate GENIE dial for future LArTPC analyses pending detector-level validation.