Papers

Validating whether the underlying physics of a model has been retained after a full phase-space reweighting poses a unique challenge. Often, validation relies on comparing histograms of 1D observables; however, this can mask correlations and biases in the complete prediction. We present a novel, unbinned approach to comparing the performance of such reweighting schemes based on the "Cross-Section-Mover's Distance", an application of Optimal Transport that quantifies the work required to transform one theoretical prediction into another and enables an interpretation of results in terms of metric spaces. We demonstrate its utility when benchmarking various reweighting schemes that mitigate the effects of negative weights in a Monte Carlo simulation. This approach can be broadly applied in other scenarios where biases in full phase-space reweighting schemes should be studied in an unbinned way.

Detailed Geant4 simulation of calorimeter showers is the largest single computing cost of collider experiments, and the High-Luminosity LHC will need about ten times more simulated events than are currently produced. We summarise recent progress in generative point cloud fast simulation for highly granular calorimeters. CaloClouds3 generates photon (electromagnetic) showers, is geometry-independent, and runs on average about 120x faster than Geant4 on a single CPU. CaloHadronic uses transformer attention to extend the point cloud diffusion approach to pion (hadronic) showers spanning the electromagnetic and hadronic calorimeters. AllShowers unifies twelve particle types in a single model with far fewer parameters than the specialised baselines while matching or exceeding their fidelity. We close with cross-geometry transfer learning, which needs two to three orders of magnitude fewer training showers while preserving the generative performance.

Cosmological correlators are calculated through the in-in formalism in (quasi-)de Sitter background. Its effective description is best represented by a reduced density matrix. In this work, we study how integrating out a massive field in de Sitter space determines the reduced density matrix of a light field at a finite observation time. Starting from a quasi-single-field model with non-linear couplings, we first evaluate the massive field wavefunctional at fixed final value and then trace over this value. The trace generates branch-mixing terms which are generally present in the Schwinger–Keldysh description. For a conformally coupled massive field, we show explicitly that the light field bispectrum from the effective description agrees with a full theory calculation. This example also shows that decay of a field at the future boundary does not by itself justify discarding its contribution to the trace. We discuss the differences between an exact nonlocal effective description and the local effective field theory obtained through a large mass expansion. We then identify which local cubic terms affect the late-time probability and which contribute only a wavefunctional phase. Finally, we organize the resulting kernels by response, noise, and Schwinger–Keldysh consistency conditions, and discuss the symmetry constraints on the reduced density matrix.

We develop Hybrid Partial Dressing (HPD), a simple diagrammatic resummation scheme for finite-temperature effective potentials in scalar field theory which is valid at all temperatures. HPD improves on earlier resummation schemes such as Daisy Resummation and Partial Dressing by being two-loop exact at all temperatures and free of the overlapping momentum problem. Renormalization group improvement is straightforward to implement. We illustrate the scheme in multi-scalar theories with a spontaneously broken $\mathbb{Z}_2$ symmetry, and compare it against existing approaches, showing in particular that it reproduces the two-loop Dimensional Reduction (DR) potential exactly in the high-temperature regime where DR applies, while remaining valid at all temperatures. This makes HPD suitable for the general study of strong first order phase transitions beyond the Standard Model, as we demonstrate through gravitational wave predictions from HPD and its RG-improved version, RGHPD.

As the accuracy of experimental results in high energy physics (HEP) increases, so does the demand for precision Monte Carlo (MC) simulation. Higher-accuracy event generation at next-to-leading order (NLO) and beyond brings with it negatively weighted events. These negatively weighted events reduce the statistical power of samples, increasing the number of events that need to be produced and straining already limited computational resources. We present a post-hoc reweighting scheme that employs cell-based resampling using an IRC-safe metric to define the cell radii. An optimal metric embeds kinematically similar events within the same cells, minimizing bias when reweighted. This motivates our exploration of a Optimal Transport (OT) based distance metrics. We compare the performance of the reweighting algorithm with different choices of metric, and explicitly demonstrate the performance on simulated Z+jets events produced at NLO accuracy.

Metastable neutron stars can undergo catastrophic conversion to quark-containing stars when a localized energy deposition nucleates a critical bubble. We show that dark-matter-induced conversions can be constrained by the present transient rate of the neutron star population, rather than by the survival of any individual hadronic star as often assumed in previous literature. Population depletion makes the present transition rate nonmonotonic: weak triggering produces few transitions, whereas sufficiently rapid triggering predominantly converts stars formed in the past. Consequently, transient observations can exclude a finite interval of interaction rates, qualitatively different from conventional one-sided survival bounds. Using the beaming-corrected short gamma ray burst rate as a benchmark, we derive constraints on dark matter annihilation, decay, inelastic particle scattering, and elastic scattering of macroscopic dark matter, including parameter space not covered by existing probes. Transient demographics thus provide a new population level probe of dark sector interactions and the phase structure of ultradense matter.

We apply physics-informed neural networks (PINNs) to recover the time-time component of static, spherically symmetric black-hole exterior metrics from a reduced ordinary differential equation (ODE). Inspired by recent work on solving Einstein field equations with deep learning~\cite{Li2023}, we encode the vacuum/charged exterior through a residual loss and an asymptotic boundary constraint—not by embedding analytic metric terms such as $2M/r$ directly into the network output. Unlike the distributed PINN (DPINN) strategy of Ref.~\cite{Li2023}, which partitions the radial domain into subdomains with separate networks, we employ a unified fully connected network over the entire interval $[r_{\min},r_{\max}]$, avoiding spurious jumps at subdomain interfaces. Moreover, whereas Ref.~\cite{Li2023} restricts training to $r\in(10,300)$—well outside the steep $1/r$ and $1/r^2$ curvature of the inner exterior—we begin at $r_{\min}=10^{-2}M$, spanning three decades in radius and covering the strongly varying region that DPINNs sidestep by domain truncation. Holding the mass fixed at $M=1$, we sweep electric charge $Q\in\{0,0.5,1.0,1.1\}$ at $\Lambda=0$ and sweep $\Lambda\in\{0,0.1,-0.1\}$ at $Q=0.5$. All configurations achieve relative $\mathcal{L}_2$ errors below $6\%$ against the analytic reference. For the representative case $Q=0.5$, $\Lambda=0.1$, three independent trainings with fixed seeds yield relative errors of $3.89\%$, $1.08\%$, and $2.76\%$ (mean $2.58\%$, standard deviation $1.41\%$), demonstrating robustness of the mesh-free approach without labeled field data.

The LUX-ZEPLIN (LZ) experiment has reported an event consistent with a $248$ keV nuclear recoil. Explaining the absence of lower-energy recoil events typically calls for some form of upscattering that kinematically forbids such events. In this work, we present a framework in which the LZ observation has a neutrino origin, with atmospheric neutrinos providing the dominant flux in the required energy range. A scenario in which atmospheric neutrinos upscatter to a heavier neutral state would also produce a large number of neutral-current events in neutrino experiments. In particular, scattering on lighter nuclear targets results in much larger nuclear recoil energies compared to xenon, yet no such excess has been observed. We show that this constraint from neutrino experiments can be evaded if atmospheric neutrinos within a narrow energy window first produce a nearly monoenergetic state $N_1$, followed by the upscattering of $N_1$ to its heavier partner $N_2$ in LZ. In such a scenario, scattering on xenon becomes kinematically allowed for $N_2$ masses around $250$ MeV, while scattering on oxygen, carbon, and other targets used in large-scale neutrino experiments remains kinematically forbidden. We show that this two-step process, $\nu \to N_1 \to N_2$, can be realized through a parametric resonance induced by a dark matter background that efficiently produces $N_1$, followed by $N_1 \to N_2$ upscattering mediated by a vector boson in a model with gauged $U(1)_B$. The latter interaction can be sufficiently stronger than the weak interaction, which is necessary to lift the neutrino floor and yield $\mathscr{O}(1)$ event at LZ.

Could a collider become the symbol of everything that must be abandoned to save the climate? In the summer of 2026, this question ran through discussions within the Particles and Fields Division of the French Physical Society. An unacceptable carbon footprint, two EPR nuclear reactors, five hundred deaths, billions to be reallocated and, to top it all, unclear scientific objectives: the objections to CERN's Future Circular Collider (FCC) appeared to form an overwhelming indictment. This essay examines each charge in turn. Grounded in a clear and compelling scientific vision, it confronts emotionally charged imagery with orders of magnitude, distinguishes a project's footprint from its full balance sheet, considers the costs of postponing or abandoning it, and explores ways of reducing its impacts-including the still uncertain prospect of natural hydrogen. The climate alone does not decide the future of the FCC; it requires us to judge the available choices by their real consequences. Developed for the public debate organised by France's National Commission for Public Debate (CNDP) and for the Swiss consultation, this essay is intended for the broadest possible readership, well beyond particle physics and the scientific community. It frames the FCC debate as a choice about the kind of society we want to build: should we organise society around renunciation and ever-shrinking horizons, or transform how we produce and choose a future worth wanting?

Exclusive photoproduction is an important probe of nuclear parton distributions at low Bjorken-$x$. The Good-Walker paradigm relates coherent photoproduction to the average nuclear configuration, giving access to the transverse distribution of gluons in a target, while incoherent photoproduction is sensitive to fluctuations such as gluonic hotspots. Efficiently separating coherent and incoherent interactions is a key challenge for experiments at the future Electron-Ion Collider (EIC). In this article, we study nuclear de-excitation via photon emission, and see how the finite photon detection efficiency leads to misidentification of incoherent emission. We compare the detection efficiency for incoherent $J/\psi$ production using the BeAGLE event generator for Ag-107, Au-197, and Pb-208 targets, for two different forward photon energy thresholds: 50 MeV and 200 MeV. The shell structures of the three species exhibit different incoherent tagging efficiencies due to differences in the lifetimes and energy levels of their excited states. Some of the low-lying states live long enough so that they decay outside the EIC detectors. Especially for the lower photon energy threshold, lead allows a higher tagging efficiency than gold, due to its lack of low-lying and/or long-lived excited states.

We propose a chain seesaw mechanism to generate not only the masses of neutral neutrinos but also the masses of charged fermions, by supplementing the standard model $SU(3)_c^{}\times SU(2)_L^{}\times U(1)_Y^{}$ gauge symmetries with an additional $U(1)_{Y'}^{}$ gauge symmetry. The chains for the down-type and up-type quarks contain different numbers of links, because the corresponding mediator vector-like fermions and new Higgs scalars carry different $U(1)_{Y'}^{}$ charges. The Peccei-Quinn global symmetry is automatically embedded in this $U(1)_{Y'}^{} $ gauge symmetry which is sufficient to guarantee the high quality of axion.

Cosmological-collider signals are usually interpreted as clean probes of massive particles present during inflation. In this work, we study a massive spectator field excited by a spatially quenched random source, which may arise from a frozen realization of a light field or environmental sector whose relaxation time is long compared with the inflationary timescale. We determine which features of the collider signal remain reliable probes of the heavy field. After Gaussian disorder averaging, the random source modifies only the statistical component of the propagator, leaving the spectral function and heavy-field poles unchanged. The particle spectrum is therefore preserved, and the logarithmic frequency of the collider oscillations remains fixed by the heavy-field mass. What changes is how the massive modes are excited and imprinted on cosmological correlators: the temporal profile of the source controls the amplitude, phase, and envelope of the oscillations. For a power-law source, the fixed-realization problem is exactly solvable in terms of Lommel functions. Decaying sources can make the nonanalytic clock signal dominant in the squeezed limit, while spatial white noise can destructively interfere with the standard collapsed-trispectrum signal. Thus, mass measurements remain robust against this class of quenched disorder, whereas amplitude-based inferences can depend sensitively on the random environment.

The observed cosmological constant is set by the deepest infrared scale of the present universe rather than by the microscopic scales that contribute to the vacuum energy. We show that this emerges as the quantum fluctuations of the gravitational field are progressively taken into account. Considering the Einstein-Hilbert+$R^2$ truncation of gravity, we find that in a wide region of the parameter space the theory develops instabilities that give rise to large amplitude quantum fluctuations which govern the renormalization group flow. Once the flow enters this region, it remains there all the way towards the infrared and progressively loses memory of its boundary conditions. The running cosmological constant $\Lambda_k$ ($k$ is the running scale) is driven towards the universal infrared scaling $\Lambda_k\sim \lambda_{_{\rm IR}}\,k^2$, with $\lambda_{_{\rm IR}}= \frac{1}{2(\pi-2)}$. At the deepest infrared scale $k_{_{\rm IR}}\sim H_0$ (the current Hubble scale), the cosmological constant is then screened to its observed value $\Lambda_{_{\rm IR}}\sim H_0^2$.

Dark matter that is weakly mixed with particles in a thermal plasma can be produced through both, oscillatory and collisional freeze-in. While plasma effects have long been known to suppress the former, their role in collisional freeze-in remains less clear quantitatively, leading to conflicting results in sterile neutrino dark matter production via collisional freeze-in. Using first-principles nonequilibrium Kadanoff-Baym equations in the flavour-covariant formulation, we establish the general result that plasma effects also suppress collisional freeze-in: the vacuum mixing angle in the collision rate is replaced by its plasma-corrected counterpart. Applying this result, we conclude that sterile neutrinos cannot be dark matter in the keV-MeV mass range when produced from the Standard Model plasma.

In this work, we extend our previous diabatic framework for the charmonium-like spectrum below $4.3$ GeV by introducing the complex scaling method. Unlike the previous framework, the present approach explicitly incorporates couplings to the meson-meson continuum, comprehensively accounting for its contributions to the physical states. Consequently, it allows bound and resonant states to be treated on an equal footing, enabling the direct extraction of decay widths from complex energy eigenvalues without introducing any additional free parameters. Using the obtained solutions, we calculate the channel weights and complex root-mean-square radii ($r_{\scriptscriptstyle{RMS}}$ ) to elucidate their internal structures. Specifically, we find that the $\chi_{c1}(3872)$, $\psi(4040)$, and $\psi(4230)$ states exhibit significant molecular characteristics. Furthermore, we propose the $X(3940)$ as a candidate for a $J^{PC}=1^{++}$ state and discuss the nature of the $\chi_{c0}(2P)$ resonance in detail.

We present first predictions from the saturation-physics-based framework IP-Glasma for the nuclear modification factor $R_{AB}$ as a function of centrality in $p$ + O, $p$ + Pb, O + O, and Pb + Pb collisions due only to initial-state effects. The same framework is responsible for both soft ($p_T \lesssim 3 ~\mathrm{GeV}$) and semi-hard ($5 ~\mathrm{GeV} \lesssim p_T \lesssim 20 ~\mathrm{GeV}$) particle production, enabling the study of initial-state correlations between bulk and intermediate-$p_T$ particle production from a first-principles framework. We show that, tuned only to HERA data, IP-Glasma accurately predicts the self-normalized multiplicity distributions in $p$ + O, $p$ + Pb, O + O, and Pb + Pb collisions; the minimum-bias nuclear modification factor in $p$ + O and $p$ + Pb collisions; the centrality-cut nuclear modification factor in $p$ + Pb collisions; and the anomalous suppression of $R_{AA}$ observed in very peripheral Pb + Pb collisions. We find that IP-Glasma predicts significantly less suppression than is measured in both $\sqrt{s_{NN}} = 5.36 ~\mathrm{TeV}$ O + O and $\sqrt{s_{NN}} = 5.02 ~\mathrm{TeV}$ Pb + Pb collisions at the Large Hadron Collider, in qualitative agreement with the scenario in which $R_{AA} < 1$ is due to final-state energy loss. We show that the inelastic nucleon-nucleon cross section ($\sigma_{\text{inel}}^{NN}$) produced by IP-Glasma is extremely sensitive to the area of the subnucleonic hotspots; the same values of the hotspot area that reproduce the measured $\sigma_{\text{inel}}^{NN}$ also reproduce minimum-bias $R_{pA}$. Finally, we show that the hard-soft correlations in IP-Glasma arise from event-by-event fluctuations in the color fields, which simultaneously drive enhanced production of both soft and hard particles.

Jets and their reconstructions play a central role in precision measurements and searches for new physics at hadron colliders. Conventional jet clustering algorithms employ a fixed radius parameter, which may not optimally describe events containing jets of varying characteristic sizes. Building on the recently proposed dynamic radius jet clustering framework, we construct several substructure-inspired dynamic radius prescriptions based on jet angularities and energy correlation functions. A detailed study of these algorithms is performed, including detector effects within the Delphes framework and in the presence of high pileup corresponding to an average of 150 interactions per event, with pileup contamination mitigated using the PUPPI algorithm. The performance of the proposed algorithms is compared with that of the standard anti-$k_t$ algorithm in boosted $Vj$ ($V=W^\pm,Z$) and $tj$ events against dijet backgrounds. Using jet substructure observables and multivariate analysis based on boosted decision trees, we find that the dynamic radius algorithms lead to improved reconstruction of boosted heavy-particle jets and achieve better signal-background discrimination compared to the conventional fixed radius anti-$k_t$ clustering.

A first-order phase transition (PT) alters a compact star on two scales: globally, via growth of a quark-matter core, and microscopically, via collision of quark bubbles, driving a simultaneous gravitational-wave (GW) emission in the kHz and MHz bands. Using a constrained ensemble of model-agnostic equations of state, we follow the accretion-driven evolution of proto-neutron stars through the PT and compute the resulting multi-band GW signal. The correlations found between the kHz emission and the MHz burst could help constrain nuclear matter and the physics of the PT. A delayed neutrino burst should accompany the signal, with the delay set by the details of the PT, thus providing a prime multi-messenger source.

Primordial black holes (PBHs) form from rare fluctuations in the high-density tail of the primordial distribution, making their abundance highly sensitive to primordial non-Gaussianity. Heavy fields during inflation can source such non-Gaussianity, producing characteristic signatures widely explored in cosmological collider physics, yet its impact on PBH formation remains largely unexamined. We investigate this question within quasi-single-field inflation (QSFI), the minimal realization that couples a heavy field to the inflaton. Unlike most PBH studies that consider only the bispectrum, the QSFI can generate a sizable trispectrum alongside the bispectrum, allowing us to investigate their combined effects on PBH formation. In our leading-order calculation, heavy-field non-Gaussianities can amplify the high-density tail and substantially enhance PBH production. Within the parameter scan, the largest enhancement occurs at the smallest heavy-field mass and the largest sound-speed ratio considered. The trispectrum contribution can be comparable to that of the bispectrum and may even dominate the total non-Gaussian correction. Our results establish PBH abundance as a novel observational channel for cosmological collider physics, demonstrating how heavy fields during inflation can significantly shape PBH formation.

The LUX-ZEPLIN (LZ) collaboration recently reported a singular anomalous nuclear recoil event at $248 \pm 23 \, \rm keV$, accompanied by a strict null result for unexplained excesses in their primary $5.4-50 \, \rm keV$ search window. The macroscopic momentum transfer required to generate this event is kinematically inaccessible to standard halo cold dark matter (CDM), naturally motivating models featuring light, relativistic relics. In this work, we investigate whether a contemporary flux of Hawking-boosted dark matter (DM) emitted by evaporating Primordial Black Holes (PBHs) in the $10^{11}-10^{13} \, \rm g $ mass range can source the anomaly. By parameterizing the nuclear scattering with heavy non-relativistic effective field theory (NREFT) operators and endothermic inelastic mass transitions, we formulate a strict kinematic exclusion. We demonstrate that the inherent thermal nature of the Hawking emission, coupled with the relativistic kinematics of the incident flux, inevitably overproduces low-energy recoils, aggressively violating the LZ background bounds. Utilizing this failure, we map the LZ low-energy null results into novel, highly stringent upper limits on the PBH abundance fraction, excluding $f_{\rm PBH} \gtrsim 10^{-6}$ for $M_{\rm PBH} \sim 2 \times 10^{11} \, \rm g $ at $ 90 \% $ confidence level.

The Method of Regions is a systematic way to derive asymptotic expansions of Feynman integrals. For Euclidean integrals there is a well-established algorithm to determine the complete set of regions as facets of a Newton polytope defined by the graph polynomials. In many physically relevant Minkowski limits, additional regions known as hidden regions are needed to obtain the correct asymptotic expansion. By making a precise connection with pinch singularities in parameter space and the associated Landau conditions, we identify the general mechanism giving rise to these regions and devise an algorithm, the Hidden Region Finder, to determine them. We show that hidden regions arise through a delicate interplay between asymptotic scaling of the edge parameters, which enhances certain monomials of the graph polynomial, and cancellations amongst these monomials, which reduce their collective contribution to the same order as other terms in the polynomial. We explore massless four-, five- and six-point integrals in a variety of wide-angle mass-shell, planar, collinear, double-collinear and Regge limits. Across these different expansions, hidden regions recur in the same small set of seed topologies. In all cases studied, they can be traced to wide-angle configurations with multiple hard-scattering subdiagrams. Distinct kinematic limits of a given seed inherit a common singular locus, while each limit fixes its own scaling vector and cancellation depth. This exploratory study showcases the potential of the proposed algorithm both to uncover missing contributions to asymptotic expansions and to organise them through their underlying singular geometry.

Monte Carlo sampling of strong-field quantum electrodynamics processes underpins simulations of high-intensity laser experiments and of astrophysical compact-object magnetospheres. Sampling an event requires the total rate of the process together with the cumulative probability that determines how energy is partitioned between the produced particles. Simulations typically tabulate both in advance and invert the tabulated probability numerically. Here we replace this procedure with elementary-function approximations for synchrotron radiation and the nonlinear Breit–Wheeler process. For each process, we approximate the auxiliary function that sets the total rate, as well as the cumulative probability, with Padé approximants chosen so that the inversion reduces to a quartic equation. This yields the sampled quantum parameter—electron $\chi_e$ or photon $\chi_\gamma$—in closed form. The approximations and the particle spectra sampled from them agree with the exact results to within $1\%$. The procedure requires no lookup tables, no interpolation, and no numerical root finding, and can be inserted directly into radiative particle-in-cell codes.

Flavour physics and CP violation play a key role for the testing of the Standard Model and search for New Physics at the high-precision frontier. After a compact discussion of the current status of (quark)-flavour physics, I will illustrate theoretical prospects for benchmark processes in the sector of decays of B mesons, ranging from precision determinations of the CP-violating phases of neutral B-meson mixing over non-leptonic decays governed by penguin topologies and channels arising only from tree diagrams to rare loop-induced decays into final states with leptons. Exciting opportunities for theorists and experimentalists arise in the era of the HL-LHC and Belle II and beyond at the FCC-ee.

This paper calculates the lepton flavor universality including the $b\rightarrow c\ell \nu$ process under the U(1) extension of the minimal supersymmetric standard model ($U(1)_X$SSM), and provides numerical analysis and summary. The numerical results are used to create one-dimensional and multi-dimensional plots to analyze the impacts of various parameters on the ratios $(\frac{R_{J/\psi}}{R^{SM}_{J/\psi}}$, $\frac{R_{{D}_s}}{R^{SM}_{D_s}}, \frac{R_{{D^*}_s}}{R^{SM}_{D^*_s}},\frac{R_{{\Lambda}_c}}{R^{SM}_{\Lambda_c}})$. The results show that several parameters have a certain effect on the ratios. Although it can't match the experimental data very well, with the right combination of parameter values, it can give better numerical results than the Standard Model. This shows that the $U(1)_X$SSM is very helpful for studying $b\rightarrow c\ell \nu$ processes.

We develop an effective axi-Higgs model with one Standard Model Higgs doublet, one charged hidden Higgs and an anomalous Abelian vector portal. Extending previous Higgs–Stueckelberg constructions, we derive the Stueckelberg kinetic term by decoupling a heavy scalar radial mode and identify the gauge-invariant physical pseudoscalar from the mixing of the surviving scalar phases. A single instanton-motivated periodic interaction determines the axi-Higgs mass, its couplings to the hidden radial excitation and the sine-Gordon kink in the fixed-radial-field limit. We construct the anomaly-canceling gauge completion, using an Abelian A–B example to introduce the mechanism before its non-Abelian hidden-sector realization. We examine the relation between the periodic potential, the hidden gauge dynamics and the theta-vacuum energy, identifying the invariant angle through the anomalous Yukawa phase rotation. The vector portal gives a coherent elastic nuclear-scattering cross section and permits additional axi-Higgs emission, whose diagrams and kinematic threshold we determine. Numerical examples illustrate the mass and interaction scales, and we investigate conditional thermal relic abundances and their cosmological implications.

We present a first background-level observational test of a thermogravity theory in which the Einstein equations are clipped to a trace-free version, the cosmological constant $\Lambda$ does not gravitate, and controlled violations of energy conservation obstruct the usual reinstatement of $\Lambda$ as an integration constant. We therefore set $\Lambda=0$ and ask whether late-time acceleration can instead be generated solely by energy non-conservation, with no extra background parameter relative to flat $\Lambda\mathrm{CDM}$. We contrast a minimal universal implementation with a model in which only CDM partakes in non-conservation. The universal model is strongly disfavored when combining Supernovae and BAO distances, with the inclusion of DESI BAO worsening the fit by $\Delta\chi^2\simeq 51$ relative to $\Lambda\mathrm{CDM}$, because matter creation ties the intermediate-redshift normalization of $H(z)$ too rigidly to the present acceleration. This conclusion, however, should be interpreted with caution, since universal non-conservation would modify the observational dictionary itself. By contrast, restricting non-conservation to CDM leaves baryonic and photon observables unaffected at the background level and therefore allows a self-contained analysis. The resulting $\xi\mathrm{CDM}$ model, which can be thought of as a one parameter extension of $\Lambda\mathrm{CDM}$, provides an improved fit relative to $\Lambda\mathrm{CDM}$ for the background dataset combinations considered, with improvements reaching $\Delta\chi^2=-4.85$ and a maximum Bayesian preference of $\ln\mathcal{B}=2.77$. However, when the BAO ruler is calibrated using BBN or CMB information, the reduced effective early-time CDM density increases the sound horizon and drives $H_0$ towards lower values, thereby increasing rather than alleviating the tension with the distance-ladder calibration.

Chiral anomalies in baryon and lepton number currents in the GUT-inspired $SO(5) \times U(1) \times SU(3)$ gauge-Higgs unification model in the Randall-Sundrum (RS) warped space are examined. Total anomalies including contributions of all Kaluza-Klein (KK) excited modes of fermions running along internal triangular loops are expressed in terms of the values of wave functions of gauge-boson KK towers at the ultraviolet (UV) and infrared (IR) branes in the RS space. The covariant divergence of 5D baryon number current picks up an anomaly term proportional to ${\rm Tr} \,F_{\mu\nu} \tilde F^{\mu\nu} |_{SU(2)_L} - {\rm Tr} \, F_{\mu\nu} \tilde F^{\mu\nu} |_{SU(2)_R}$ at the UV and IR branes where $SU(2)_L \times SU(2)_R$ is a subgroup of $SO(5)$.

Recent stellar-kinematic and neutral-hydrogen observations indicate a dark matter deficit within the central tens of kiloparsecs of nearby galaxies that grows systematically with stellar mass relative to hydrodynamical simulations. We show that this mass dependence can arise from exothermic inelastic dark matter with strongly velocity-dependent scattering. Two nearly degenerate dark matter states interact through vector and scalar mediators with opposite-sign contributions and unequal ranges. The resulting coupled-channel dynamics suppresses $s$-wave conversion at low velocity while retaining a $p$-wave enhancement at several hundred $\rm km/s$, where down-scattering injects kinetic energy and lowers central dark matter densities. At dwarf velocities, conversion remains suppressed while elastic scattering can still drive core formation consistent with the observed dwarf-clustering pattern. A late dark-sector phase transition, along with the low-velocity suppression, preserves a large excited-state fraction until halo formation. Using representative halos spanning the four observed stellar-mass bins, we find that the model accounts for the inferred dark matter deficit in all four bins, including its systematic growth with stellar mass, while its impact weakens toward cluster velocities. The growing discrepancy with hydrodynamical simulations may therefore offer a glimpse of previously hidden dark matter microphysics.

Observations of collective signatures within jets of particles have been recently reported by measurements at the Large Hadron Collider at CERN laboratory, providing insights on the minimum conditions required for forming a Quark Gluon Plasma state. A quantitative comparison with data measurements on intrajet azimuthal anisotropies and predictions from PYTHIA event generator soft QCD model parameter tunes: Monash, CP5, and QCD-scheme CR is presented. Energetic jets with transverse momentum over 550 GeV from proton-proton collisions at 13 TeV are reconstructed. Results from predictions using the standard E-scheme (ES) and jet axis choice are compared with those from the Winner-Take-All (WTA) frame. Significant differences are present between predictions from WTA and ES frames at the lowest and highest intrajet charged particles multiplicities ($N_{\mathrm{ch}}$), with the QCD-scheme CR tune showing the smallest variation between frames. Predictions for $v_2$ at the highest $N_{\mathrm{ch}}$ are consistent with the data measurements at a 2.3$\sigma$ uncertainty level. These results set new guidance towards the search for intrajet collective effects and understanding of nonperturbative QCD dynamics originated from a single parton.

We show that a three-body holonomy can select the conventional $SU(3)\to SU(2)\times U(1)$ breaking direction. Three particles are special in the present construction: after removal of the center-of-mass coordinate they are the minimal one-dimensional few-body system with a two-dimensional relative space, allowing a closed cycle around the triple-coincidence point once pairwise contacts are encoded by matching conditions. A cyclic three-state mass operator gives \[ M^{[k]}=M_0+2\Delta\cos\!\left(\frac{\theta_3+2\pi k}{3}\right),\qquad k=0,1,2. \] At $\theta_3=0$ the spectrum splits as $3\to2+1$, and the induced mass operator is proportional to the Cartan generator $T_8$. Its commutant is therefore $SU(2)\times U(1)$. In a trinification-like embedding, distinct left- and right-sector holonomies leave the hypercharge combination which reproduces the Standard-Model hypercharges for the usual trinification matter assignment. The construction is a toy mechanism for selecting the breaking direction; additional dynamics are required for rank reduction and vacuum selection.