Papers

Enhanced density fluctuations form early dark matter halos, which serve as early gravitational potential wells for baryons. These baryons can then condense to form stars and black holes at high redshifts, $1+z \gtrsim 100$. Larger density fluctuations result in denser halos with higher virial temperatures; hence, a halo at a mass that is below the threshold for forming stars under standard astrophysical expectations may form astrophysical objects if its initial density is higher than expected, although the exact threshold for compact object formation is subject to large astrophysical uncertainties. We outline the conditions under which enhanced density fluctuations form dark (star-less) halos, early galaxies, or even star clusters. Using toy model enhancements to the primordial power spectrum that have been shown to explain the abundances of “little red dots", along with our fiducial set of astrophysical parameters, we show that the number of clusters initially captured by the Milky Way is highly sensitive to the shape of the enhancement, with the narrowly peaked enhancement resulting in $50$ clusters and the step-function enhancement resulting in $\sim 4.1 \times 10^5$. The initial stellar masses of the clusters is also $O (100) \,M_\odot$, although this range is also dependent on the shape of the enhancement. In addition, the abundance of dark matter subhalos with masses greater than $10^7 \, M_\odot$ can be enhanced by as much as a factor of $\sim 6.5$ and is denser than in $\Lambda$CDM, which will increase their detectability in future stellar stream surveys such as the Via Project.

We analyse the process $e^+e^-\to h\gamma$ in the Standard Model (SM) and in generic extensions with heavy new physics, using the framework of Higgs pseudo-observables. We decompose the one-loop amplitude into separately gauge-invariant photon-pole, $Z$-pole, and non-pole contributions. For heavy new physics, we show that the leading deviations from the SM are necessarily encoded in the $h\gamma\gamma$ and $hZ\gamma$ on-shell effective couplings. Genuine $e^+e^-h\gamma$ contact interactions arise only at higher orders in a derivative expansion, both in SMEFT and HEFT. Although Higgs decays constrain the magnitudes of these pseudo-observables, they leave their relative sign undetermined. Measurements of $e^+e^-\to h\gamma$ at different FCC-ee energies can resolve this ambiguity. Deviations incompatible with this description would instead point towards relatively light new degrees of freedom, as illustrated by a simplified $Z'$ model.

We show that the large-$z$ behavior of massive higher-spin particles under all-line transverse shifts is controlled by the helicity magnitude rather than the total spin. The apparent additional $z$ growth of nonextremal higher-spin wavefunctions is removed by unified Ward identities acting independently on each vector index. To expose this structure, we embed a four-dimensional massive momentum and its mass into an auxiliary null five-vector, whose fifth-current components characterize the breaking and restoration of the massless Ward identities. These identities determine the fixed-helicity large-$z$ scaling and yield a helicity-resolved constructibility criterion valid for arbitrary spin. Provided the stripped kinematic tensor remains finite in the massless limit, increasing the total spin does not by itself worsen constructibility, and amplitudes with nonnegative coupling dimension are constructible for all helicity configurations at five points and beyond.

We analyze Higgs production at the LHC with a jet veto at central rapidities and present the first next-to-leading logarithmic resummation of non-global logarithms for this process. The resummation combines one-loop hard and soft matching functions with two-loop anomalous dimensions in the large-$N_c$ limit. To perform the resummation we numerically solve renormalization group equations via the parton-shower framework MARZILI. After matching to fixed order, we perform a detailed study of different sources of uncertainties. We find that the hard matching corrections dominate by far and are substantially larger than in Drell-Yan production. Together with earlier results for Drell-Yan, these are the first resummations of subleading non-global logarithms in hadron-collider cross sections, and they provide a benchmark for logarithmically accurate parton showers.

We present new constraints on sub-GeV dark matter (DM) annihilation and decay using twenty years of diffuse hard X-ray observations from the INTEGRAL/IBIS telescope. By performing a joint analysis of the spectral and morphological information contained in the IBIS dataset, we simultaneously fit Galactic longitudinal profiles and energy spectra, exploiting their complementary signatures to disentangle potential DM signals from the dominant astrophysical backgrounds. We use physically motivated background models combining inverse-Compton (IC) emission from Galactic cosmic-ray electrons with thermal emission from unresolved accreting white dwarfs, and consistently include the secondary IC emission generated by DM-induced electron and positron populations propagated through the Galaxy. We conservatively derive 95% upper limits on the annihilation cross section $\langle\sigma v\rangle$ and decay half-life $\tau$ for the $e^+e^-$, $\mu^+\mu^-$, and $\pi^+\pi^-$ final states across the mass range 1 MeV to 5 GeV. Our constraints are in the range $10^{-28}$ cm$^3$/s $\lesssim \langle\sigma v\rangle \lesssim 10^{-26}$ cm$^3$/s for annihilation and $\tau \gtrsim 10^{25}$ s for decay at DM masses of a few MeV, improving upon existing X-ray limits by up to two orders of magnitude over much of the mass range. Our bounds are translated into constraints on the kinetic mixing parameter $\epsilon$ of a dark photon and the scalar-Higgs mixing angle $\sin\theta$, and compared with existing indirect, direct and accelerator limits available, providing a comprehensive picture of the allowed parameter space for light portal DM.

The primordial scalar power spectrum provides a powerful window onto early-universe physics, including a broad class of inflationary scenarios. These models often predict a characteristic scalar spectral index $(n_s)$, nonzero running $(\alpha_s)$, or more general deviations from a pure power-law form. We find that freeing the number of light relic species $(N_{\rm eff})$ and the sum of the neutrino masses $(\sum m_\nu)$ broadens the $n_s$ error contours enough that key early-Universe models are no longer excluded. In particular, while both Starobinsky inflation and the Bi-thermal Big Bang model are ruled out at about the 95% confidence level in the six-parameter $\Lambda$CDM model, we find that in the nine-parameter $\Lambda{\rm CDM} + \alpha_s + N_{\rm eff} + \sum m_\nu$ model, CMB data from Planck, ACT, and SPT (CMB-PAS) combined with DESI DR2 give $n_s = 0.9758 \pm 0.0064$ and $\alpha_s = 0.0080 \pm 0.0064$, consistent with both models. Future CMB facilities will sharply improve constraints on $n_s$, $\alpha_s$, and, more generally, the binned primordial power spectrum $\mathcal{P}(k)$. For example, CMB-PAS constrains $e^{-2\tau}\mathcal{P}(k = 0.2\,{\rm Mpc}^{-1})$ to 0.5%, while SO-like and CMB-HD-like surveys would tighten this to 0.1%; CMB-HD would also extend this measurement to smaller, previously unprobed scales, constraining $e^{-2\tau}\mathcal{P}(k = 30\,{\rm Mpc}^{-1})$ to within a factor of ten. We release our forecast code and update the public CMB-HD likelihood and Fisher codes to support CLASS in addition to CAMB.

The detection of gravitational waves in the low-frequency band (10 nHz to 1 micro-Hz) using inner solar system proof masses is severely limited by Newtonian gravity gradient noise (GGN) sourced by the asteroid belt. In this paper, we propose a novel detection concept that exploits the relativistic nature of gravitational waves to break the degeneracy between the signal and the asteroid GGN background. The non-relativistic motion of asteroids dominantly sources gravito-electric fields, with velocity suppressed gravito-magnetic components. Relativistic gravitational waves produce gravito-electric and gravito-magnetic components of equal magnitude. We propose detecting the gravito-magnetic component of low frequency gravitational waves using the Lorentz acceleration of test bodies. The measurement of this Lorentz acceleration is metrologically possible due to the fact that expected astrophysical sources of low frequency gravitational waves have considerably higher characteristic strains than the strains typically expected at higher frequencies. We show that this measurement allows for unambiguous extraction of the gravitational wave signal from the gravity gradient noise in a three satellite constellation. The gravito-magnetic measurement still requires a proof mass that is well isolated from non-gravitational noise. We propose the use of atom interferometers to serve as such a pristine inertial reference.

Standard-Model warm inflation (SMWI) makes QCD the microscopic origin of inflationary dissipation, so the real-time response of the gauge plasma enters the cosmological prediction. We show that a slowly relaxing gauge-helicity response cannot, in general, be absorbed into an effective friction coefficient and must instead remain dynamical. We therefore evolve the quark axial densities and a matched hard-helicity mode, with QCD sphalerons and an effective $2\leftrightarrow3$ channel generating both charge transfer and correlated stochastic sources in the full perturbation covariance system. The resulting backreaction is substantial but mainly indirect: gauge-helicity screening can reduce the warm dissipation ratio by an order-one fraction on the strong branch, while the $2\leftrightarrow3$ channel contributes only $0.2\%-0.7\%$ of the zero-density sphaleron friction directly, shifting the amplitude-normalized trajectory in both $n_s$ and $r_{\rm vac}$. The relevant trajectories, however, lack a parametrically broad hard-soft hierarchy and extend beyond strict linear response. The predictions should therefore be understood within the stated local Gaussian transport closure; a parameter-free Standard-Model (SM) result requires finite-affinity real-time $SU(3)$ drift, susceptibility, and noise kernels.

Machine-learning-based anomaly detection (AD) offers a promising, model-agnostic alternative to traditional LHC analyses, allowing to search for many signals at once. Recent advances in representation learning motivate the use of neural embeddings to map high-dimensional physics observables into low-dimensional latent spaces better suited to statistical inference. However, the propagation of systematic uncertainty in embedded spaces remains poorly understood, severely limiting the application of these methods to real LHC analyses. We address this gap with a machine learning strategy that uses a likelihood-based regularization to improve the structure of embedded spaces. Building on previous work using supervised contrastive learning for physics-aware embeddings, our approach trains them jointly with a downstream parameterized classification task that incorporates continuous uncertainties as nuisance parameters. This method returns a latent space that covaries predictably with systematic shifts, and a model of such distortions that can be exploited in the downstream statistical test for anomaly detection. Using simulated CMS Level-1 trigger data, we show that our method successfully models continuous uncertainties in a 4D latent space with a linear parametric downstream classifier, improving both the interpretability and robustness of the statistical anomaly detection task. This framework offers a general way to study and control systematic uncertainties in latent spaces, opening the way to a new scalable statistical analysis workflow for anomaly detection at the LHC, and other high energy physics experiments.

The interpretation of high-energy nuclear recoils in direct-detection experiments can depend sensitively on the high-velocity tail of the galactic dark matter (DM) distribution. The LUX-ZEPLIN (LZ) experiment has recently reported an event, LZ230616, with nuclear recoil energy 248 $\pm$ 23 (stat) $\pm$ 23 (sys) keV, while the Gaia mission has provided an unprecedented view of the kinematics and mass distribution of the Milky Way. We bring these two probes together to investigate the inelastic DM interpretation of LZ230616, using a velocity distribution inferred from Gaia-informed galactic model. Compared to the Standard Halo Model, the resulting distribution has a lower escape speed and a significantly suppressed high-velocity tail, with a higher local density. We find that while the exothermic interpretation is largely insensitive to this change, the endothermic interpretation requires substantially larger scattering cross sections and smaller mass splittings. Furthermore, using simulation-based study of the gravitational effects of the Large Magellanic Cloud, we show that the high-velocity tail can extend the allowed endothermic parameter space towards lower DM masses and larger splittings. Our results demonstrate how combining direct searches for DM detection with precision measurements of galactic dynamics can qualitatively affect the particle-physics interpretation of high-energy nuclear recoils.

We develop a new framework to perform a virtuality-resolved description of jet propagation in heavy-ion collisions using perturbative techniques. The role of virtuality is rigorously identified by first deriving a factorized jet cross section that defines an in-medium jet function. This new definition allows to extend the usual BDMPS-Z formalism to include the virtuality-differential transverse momentum broadening distribution and medium-induced soft gluon spectrum. We study both the cases of a medium which is created with some delay time $\tau_0$ after the hard collision as well as the case in which $\tau_0\to 0$. Integration over the complete virtuality range recovers the standard BDMPS-Z results, while finite virtuality reveals the interplay between vacuum-like evolution and medium-induced dynamics. We identify the ratio between the medium formation time and the jet formation time as the variable controlling which initial virtualities contribute appreciably to the jet function.

The LUX-ZEPLIN (LZ) experiment has reported a single nuclear-recoil candidate at $E_R \simeq 248$keV. LZ interprets it in terms of inelastic dark matter that scatters endothermically from its ground state, $\chi_1 N \to \chi_2 N$. In pseudo-Dirac models the excited state $\chi_2$ can survive to the present day, and exothermic scattering, $\chi_2 N \to \chi_1 N$, is then also open. The published LZ intervals do not describe this case. We rebuild the LZ statistical inference and validate it against the published intervals. We then apply it to a halo that contains a fraction $f$ of $\chi_2$. For $f \gtrsim 10^{-5}$–$10^{-2}$, depending on the mass splitting, the exothermic contribution dominates. For $f=1/2$ the cross section required by the candidate drops by factors of $80$ to $1.6\times10^4$ for $\delta = 250$–$350$~keV, and the kinematic cutoff of the endothermic signal disappears. A benchmark that explains the event with $\chi_1$ alone lies a factor of $30$ above the upper limit when half of the halo is $\chi_2$.

Measurements of heavy-flavor baryons in nucleus–nucleus and proton–proton collisions have provided strong evidence that heavy-quark hadronization cannot be described solely in terms of vacuum fragmentation. In particular, the large enhancement of the $\Lambda_c/D^0$, $\Xi_c/D^0$ and $\Omega_c/D^0$ ratios observed at RHIC and LHC energies has been successfully described within a coalescence plus fragmentation approach, supporting the relevance of recombination mechanisms in both large and small collision systems. Building on these results, we discuss recent developments in the coalescence hadronization framework. Particular emphasis is given to the production of multi-charmed baryons, namely $\Xi_{cc}$, and $\Omega_{ccc}$, whose yields are predicted in a wide range of collision systems from PbPb to KrKr, ArAr and OO collisions. The strong sensitivity of these states, especially $\Omega_{ccc}$, to the underlying charm-quark distribution makes them valuable probes of charm thermalization and non-equilibrium effects in the QGP. We also present recent extensions of the model to the beauty sector, including predictions for $\Lambda_b/B^0$, $\Xi_b/B^0$ and $\Omega_b/B^0$ production. The results indicate sizeable recombination effects and a stronger baryon enhancement than in the charm sector, highlighting the increasing role of coalescence for heavier quarks. Finally, we briefly comment on ongoing developments toward a unified description of open and hidden heavy flavor through the application of the same framework to quarkonium production in small collision systems.

We study the spin-resolved spectral functions of $\phi$ and $K^{*0}$ in a thermal hadronic model with a constant magnetic field. We construct the rest-frame retarded propagators by combining real vacuum matching with exact Landau levels, connection contacts, and thermal scattering terms. The resulting stable-daughter calculation is checked against independent collision kernels and published expressions in common limits. We find that closed transverse thresholds give rise to narrow peaks with eV-scale detunings, whose areas must be resolved in the calculation of small spin spectral moments. We test the leading threshold estimate for the peak area by an independent integration of the full kernel. Using positive compact daughter spectra, we then investigate how a finite spectral spread changes the local threshold structure. The disappearance of zeros of the real part of the inverse propagator is controlled by the spread relative to the detuning, whereas the weight integrated over a finite patch can remain nearly unchanged. We relate this redistribution to smooth accepted moments through a weighted identity with a bounded Taylor remainder, and evaluate the complete-window response to three endpoint replacements, including the patch complement. For the stable-daughter $\phi$ spectra with a fixed smooth weight, the response at the two smallest sampled fields is negative and compatible with $b^2$ scaling. Hard-window results instead oscillate in sign, and pseudoscalar mixing substantially changes the smooth response coefficient. These results quantify the sensitivity to thresholds and spectral projection; microscopic daughter widths and source-matched experimental spin alignment require additional input.

We investigate the effective axial $U_A(1)$ symmetry restoration at finite temperature in an external magnetic field using meson screening masses, as well as meson susceptibilities, in a $(2+1)$-flavor Nambu-Jona-Lasinio (NJL) model. To incorporate inverse magnetic catalysis, we employ a magnetic-field-dependent four-quark coupling constrained by the lattice QCD chiral pseudo-critical temperature, with the 't Hooft coupling fixed. In the lattice-improved NJL model, the longitudinal screening mass difference between the $U_A(1)$ partners $\delta^0$ and $\pi^0$ and their normalized meson susceptibility difference exhibit axial magnetic catalysis at low temperatures and axial inverse magnetic catalysis near the chiral crossover, whereas the transverse screening mass difference increases with $eB$ at all temperatures. Despite these different responses, the axial pseudo-critical temperatures extracted from the thermal inflection points of these three alternative order parameters decrease with $eB$, implying that a decreasing pseudo-critical temperature can coexist with an increasing transverse screening mass difference at fixed temperature.

In the context of precision physics, the resummation of large logarithms of the variable $x = Q^2/s$ is increasingly relevant at high energies. We report here preliminary results on the extension of the differential resummation formalism within the HELL framework to Higgs boson production via gluon fusion.

We investigate the impact of resummation-scale variations on parton distribution function (PDF) determinations. These variations introduce an additional source of theoretical uncertainty related to the evolution of PDFs and strong coupling $\alpha_s$ that has never previously been accounted for in PDF fits. Using the open-source xFitter framework, we quantify this uncertainty in fits to HERA deep-inelastic scattering data and examine its implications for predictions of top-quark pair production at the LHC. We show that the resulting resummation-scale uncertainties have a sizable impact on LHC observables, highlighting the importance of including this source of uncertainty in precision QCD analyses.

Single inclusive hadron suppression in high-energy heavy-ion collisions provides a sensitive probe of parton energy loss and jet transport coefficient in quark-gluon plasma (QGP). System size dependence of jet quenching can provide further constraints on the dynamics of jet quenching and parton energy loss. Motivated by recent experiments on light-ion collisions at the Large Hadron Collider (LHC), we perform a systematic study of single-inclusive hadron suppression in O+O, Ne+Ne, Xe+Xe and Pb+Pb collisions at the LHC energies. The calculations are carried out within the next-to-leading-order perturbative QCD model, incorporating the nuclear modified initial-state parton distributions, final-state parton energy loss in the higher-twist approach and the temperature dependence of the jet transport coefficient $\hat q/T^3$ from the Bayesian analyses of previous experimental data at the Relativistic Heavy-ion Collider (RHIC) and LHC. Our model calculations can simultaneously describe the measured single-inclusive charged hadron $R_{AA}$ in O+O, Ne+Ne, Xe+Xe and Pb+Pb collisions over a broad range of event centralities and in the minimum-bias events. We further illustrate the system size dependence of jet quenching through the ratio $R_{\mathrm{NeNe}}/R_{\mathrm{OO}}$ and the modification factors $R_{AA}$ as a function of $\langle N_{\mathrm{coll}} \rangle$ which follow a common behavior at fixed $p_{\rm T}$, indicating the formation of QGP even in the smallest collision systems.

While the type-I seesaw model provides an attractive framework for simultaneously explaining the origin of neutrino masses and the baryon asymmetry of the Universe, flavor symmetries offer a natural approach to understanding the observed neutrino mixing pattern. However, the highly constrained neutrino mass structures predicted by flavor symmetries may also prevent conventional leptogenesis to work. In particular, when the Dirac neutrino mass matrix $M^{}_{\rm D}$ or the Majorana right-handed-neutrino (RHN) mass matrix $M^{}_{\rm R}$ is exactly degenerate (namely, they are proportional to the identity matrix $I$), the CP asymmetry of RHN decays will vanish either due to the orthogonality of different neutrino Yukawa coupling columns or the exact degeneracy of RHN masses. In this work, we propose that the flavon fields (which are inherently present in flavor-symmetry neutrino mass models to be responsible for generating the nontrivial neutrino flavor structure) can naturally overcome these obstacles. For the case of $M^{}_{\rm D} \propto I$, flavon–RHN interactions induce additional decay channels $N_I \to N_J \phi$ and generate new CP-violating contributions to RHN decays. For the case of $M^{}_{\rm R} \propto I$, three-body decays $N_I\rightarrow L^{}_\alpha H\phi$ mediated by heavy vectorlike fermions provide a CP asymmetry source even when the RHN masses are exactly degenerate. Our results demonstrate that the flavon sector provides a natural connection between neutrino flavor structure and leptogenesis, offering a new mechanism for leptogenesis in flavor-symmetry-based neutrino mass models.

Vector-vortex photons, characterized by a nonseparable coupling between polarization and orbital angular momentum (OAM), offer opportunities for optical manipulation, quantum communication, nuclear photonics, etc. However, their generation in the $\gamma$-ray regime remains challenging. Here, we put forward a novel method to generate vector-vortex $\gamma$ photons via nonlinear Compton scattering in elliptically polarized laser pulses. We reveal that tailoring laser ellipticity directs the multiphoton absorption to coherently populate OAM modes with opposite winding numbers, $\pm \ell$, tied to orthogonal circular polarizations, producing nonseparable spin-OAM photon states. For a linearly polarized laser of moderate intensity (dimensionless amplitude $a_0 \sim 1$), the mode-pair concurrence–a 0-to-1 measure of spin-OAM entanglement–reaches unity for MeV $\gamma$ photons, realizing maximally nonseparable radial- or azimuthal-type vector-vortex states. The laser amplitude further controls the accessible OAM spectrum. Our method offers a route to MeV vector-vortex photons, opening a new avenue for nuclear-scale structured photonics and high-energy quantum information.

We present the first calculation of the leading perturbative quantum chromodynamics (QCD) correction to the nonleptonic weak flavor-equilibration rate in dense quark matter. The computation is based on the Kadanoff-Baym kinetic equation and performed using real-time thermal field theory. The resulting QCD correction is both gauge invariant and fully finite. In particular, all soft and collinear divergences cancel after combining real and virtual corrections, in accordance with the Kinoshita-Lee-Nauenberg theorem. In the low-temperature regime relevant to compact-star dynamics, the correction enhances the tree-level rate by $30 - 40\%$ over the high-density range where perturbative QCD is applicable. The corrected rate improves on the tree-level result used in phenomenological calculations for more than three decades, providing a more accurate microscopic input for bulk-viscosity calculations in dense quark matter.

The relaxation-time Boltzmann equation governs relativistic matter far from equilibrium, but existing approaches rely on finite-order truncations that break down in this regime. We introduce ShARK (Stochastic Advection Relaxation Kinetics), the first fully 3D Monte Carlo kinetic framework to capture exact, far-from-equilibrium ultrarelativistic dynamics for arbitrary initial conditions while directly enforcing target transport coefficients, converging to the exact Anderson-Witting solution. Validated against the Bjorken and Gubser flows, the framework reproduces the exact kinetic result where truncated methods fail.

We show that the Anderson-Witting relaxation-time approximation (relativistic Bhatnagar-Gross-Krook (BGK) equation) emerges as the $N\rightarrow \infty$ limit of a stochastic $N$-body particle gas, in which collisions perform a full microcanonical momentum redraw that enforces local energy-momentum conservation at every event. Using the RAMBO algorithm to sample the Lorentz-invariant phase space, we derive the finite-$N$ single-particle momentum spectrum and show that it converges to the Jüttner-Boltzmann equilibrium distribution as the local particle number grows. We couple this relaxation kernel to an advection-relaxation splitting scheme to construct ShARK (Stochastic Advection Relaxation Kinetics), a 3D Monte Carlo relativistic solver for the relaxation time approximation Boltzmann equation. The framework is conceptually related to lattice Boltzmann methods, but formulated in continuous momentum space to avoid the accuracy loss caused by finite-order momentum discretizations far from local equilibrium. We validate the numerical results against analytical solutions for two highly symmetric conformal expansions, the Bjorken and Gubser flows. The framework provides a first-principles route to far-from-equilibrium relativistic transport, with applications ranging from heavy-ion collisions to expanding astrophysical plasmas.

We present a relativistic momentum-space framework for femtoscopic correlation functions including strong and Coulomb interactions in coupled channels. The approach extends the Vincent–Phatak prescription to the three-dimensional Bethe–Salpeter equation, combining a fully relativistic treatment with the correct Coulomb asymptotics through wave-function matching. We apply it to the $D\pi$ system using a coupled-channel heavy-meson chiral interaction that reproduces the established two-pole structure of the $D_0^*(2300)$. Our correlation functions agree with previous theoretical calculations but differ significantly from those extracted by the ALICE Collaboration. We trace this tension to the assumption made in the experimental analysis that the genuine correlation function reaches unity above a relative momentum of $100$ MeV, whereas this region remains affected by the lower $D_0^*(2300)$ pole. Repeating the extraction over different fitting windows reveals a strong dependence of the extracted signal on the chosen range, demonstrating that the resulting $D\pi$ scattering parameters are not robust and motivating a dedicated reanalysis of the experimental data. We extend the analysis to the $D^*\pi$ system, where the same issue arises in close connection with heavy-quark spin symmetry. Together with the unresolved tension between theoretical calculations and the ALICE $K\pi$ femtoscopic measurements, this highlights the need to clarify the origin of this puzzle, with the aim of establishing femtoscopy as a reliable quantitative tool for precision studies of low-energy hadron interactions.

Given a high-energy astrophysical neutrino flux, its source flavor ratios $\eta = \{\eta^{}_e, \eta^{}_\mu, \eta^{}_\tau\}$ are correlated with the ones $f = \{f^{}_e, f^{}_\mu, f^{}_\tau\}$ measured at a neutrino telescope via $f = P \eta$, where the elements of $P$ consist of four lepton flavor mixing parameters. But realistic inverse flavor mapping $\eta = P^{-1} f$ encounters unavoidable parameter degeneracy and information loss, especially in or near the $\det P = 0$ limit allowed by current neutrino oscillation data. In this work we explore the parameter correlation condition for $\det P = 0$ including the $\mu$-$\tau$ reflection symmetry case, formulate the corresponding constraints on $f^{}_e$ and $f^{}_\mu$ versus $\eta^{}_e$ and $\eta^{}_\mu$, and illustrate to what extent the source flavor distribution can be mapped by using the recent IceCube all-sky neutrino flux data ranging from 5 TeV to 10 PeV under the assumption that the relevant sources have a common flavor composition.

Recent progress in the understanding of meson photoproduction, obtained from the joint effort of the Joint Physics Analysis Center (JPAC) and the GlueX and CLAS experiments at Jefferson Lab, is reviewed. The photoproduction of the $\eta\pi$ system is now well understood, from the $a_2(1320)$ resonance region to the high-mass region dominated by double Regge exchanges. Since the lightest hybrid meson, the $\pi_1(1600)$, is expected to decay predominantly into $b_1\pi$, reactions with a recoiling $\Delta^{++}$ are promising channels for exotic searches. As a first step towards $\gamma p \to b_1 \pi \Delta^{++}$, the complete angular distribution of $\gamma p \to \rho^-\Delta^{++}$ with a linearly polarized photon beam is derived. It involves 56 double-index spin-density matrix elements, which describe the correlations between the $\rho$ and the $\Delta$ decays. When the production amplitudes factorize, as is the case for the exchange of a single Regge pole, the intensity reduces to the product of the standard $\rho$ and $\Delta$ decay distributions and depends on only 14 parameters.

Super-leading logarithms from Glauber exchange complicate the resummation of non-global observables at hadron colliders. In this Letter, we extend Marzili, a Monte Carlo framework for non-global resummation based on effective field theory, to resum the leading nonzero colour contribution involving two Glauber exchanges. This is the first Monte Carlo resummation of super-leading logarithms. Together with Marzili's treatment of non-global logarithms, this opens a path towards studying their interplay and incorporating Glauber exchange into parton showers.

We investigate the twist-4 generalized transverse momentum dependent parton distributions (GTMDs) of $\bar{u}$ and $\bar{d}$ quarks inside the proton at zero skewness by adopting the overlap representation within the light-cone formalism. Using the light-cone wave functions of the proton derived from the baryon-meson fluctuation model in terms of the $|q\bar{q}B\rangle$ Fock states, we calculate the twist-4 GTMDs of $\bar{u}$ and $\bar{d}$ quarks. Additionally, the intricate relations between the GTMDs and the generalized parton distributions are also explored in our research. Numerical results for these twist-4 GTMDs and twist-4 GPDs at zero skewness are analyzed and presented.

In the present study, we investigate the phase diagram of strongly-interacting fermions under imaginary rotation. We employ the linear sigma model coupled to quarks in the mean field approximation. The fermion expectation values are computed in the local density approximation (LDA), using the well-known expressions derived using cylindrical modes for states under rigid rotation, at finite temperature $T$ and chemical potential $\mu$. We study the impact of the fractalization of thermodynamics on the phase diagram in the far-field limit (far from the rotation axis). We also reveal non-trivial features such as a complete inhibition of the chiral symmetry restoration on the rotation axis above a critical imaginary angular velocity. We demonstrate explicitly how the transition line interpolates between its shape on the rotation axis and in the far-field limit by studying the chiral phase transition at finite distances from the rotation axis. We also address the moment of inertia of the system and discuss differences and similarities to lattice studies of QCD matter under imaginary rotation.

We briefly discuss recent results on the four-loop splitting functions for the scale dependence of the parton distributions of hadrons. The three non-singlet cases are now completely known. The results agree with almost all expectations, but exhibit some small-$x$ double logarithms not encountered at lower orders. The flavour-singlet cases include, as already obvious from the present partial results, analytical structures not seen in the splitting functions up to now. The numerical effects (and their uncertainties, in the singlet cases) of the four-loop contributions to the scale derivatives amount to about $1\%$ or less down to momentum fractions $x$ as low as about $10^{-4}$ at a standard benchmark point with $\alpha_{\rm s} = 0.2$, with the exception of the total valence quark distribution.