Papers

We compute the leading order modification to the quark-antiquark-$W$-boson vertex in the presence of a constant and uniform magnetic field, specifically for the case where the quark and antiquark are the $u$ and $\bar{d}$, respectively. We find the selection rules for transitions where the $u$, $\bar{d}$, and $W$-boson occupy arbitrary Landau levels. We show that, for the particular case where the initial particles each occupy the lowest Landau level, the $W^+$ is also produced in the lowest Landau level with a single polarization aligned with the magnetic field. We also illustrate the general findings by computing the case of transitions between low lying Landau levels and show the correspondence between the polarization vectors for the $W$-boson and the polarization states for the quark and the antiquark.

This thesis studies 4D F-theory compactifications with fluxes and their connection to particle physics, accompanied with a review of F-theory. First, we develop a general formalism for gauge symmetry breaking with fluxes. Vertical and remainder fluxes can be used to break a rigid gauge group, with the former simultaneously inducing chiral matter, even when the unbroken gauge group has no complex representations. We show that it is fairly likely to have three generations of chiral matter. We focus on the realization of the Standard Model gauge groups and chiral matter by breaking rigid $E_7,E_6$ gauge groups with an intermediate SU(5) gauge group, and provide examples of explicit constructions. Then, the phenomenological aspects of rigid $E_7$ models are studied in detail. We find that many other Standard-Model like features are naturally compatible with the $E_7$ models. For example, dimension-4 and dimension-5 proton decay are ubiquitously suppressed. Many of these features are due to the group-theoretic structure of $E_7$ and its F-theory geometry. In particular, a set of approximate global symmetries descends from the $E_7$ group, leading to exponential suppression of undesired couplings. These features suggest a new set of grand unified theories based on the $E_7$ group and its string theory construction. Finally, we study constructions of abelian gauge symmetries with exotic charges. By breaking a rigid nonabelian group to a U(1) gauge group using vertical flux, very large charges can arise in the massless or light spectrum. We give an explicit construction in 4D F-theory in which the vector-like matter carries charges as large as 657, which is much larger than the previously known bounds in F-theory. We heuristically argue that this result may provide an upper bound on charges for light fields under decoupled U(1) gauge groups in the F-theory landscape.

We study electromagnetic radiative corrections to neutron $\beta$ decay within chiral perturbation theory extended to include the $\Delta(1232)$ resonance as an explicit degree of freedom. Building on a previous analysis performed in the $\Delta$-less theory, we identify and compute additional loop contributions with intermediate $\Delta$ states at leading and next-to-leading order in the small-scale expansion, and match the results to the pionless effective field theory. We find that the convergence of the chiral expansion significantly improved in the $\Delta$-full calculation. The electromagnetic shift in the axial coupling is reduced by $25\%$ compared to the $\Delta$-less result. The correction remains at the percent level and is phenomenologically significant for the comparison between experimental extractions and lattice-QCD determinations of the nucleon axial charge. We also obtain a new $\Delta$-induced contribution to the weak magnetism term, which is an order of magnitude smaller than the pion-loop result and negligible for upcoming experiments.

We propose projected energy correlators measured on the recoiling QCD radiation of a $Z/\gamma$ as a benchmark observable for precision QCD at the LHC. Using the $Z/\gamma$ as a hard scale prevents the need for a jet algorithm, simplifying both the perturbative and non-perturbative corrections. We develop a framework to combine state-of-the-art fixed-order amplitudes, high order resummation, and universal non-perturbative matrix elements. Our approach is based on numerically computed inclusive hard functions, allowing flexibility in the process and the inclusion of realistic experimental cuts. We perform detailed numerical studies of the projected energy correlators at next-to-leading order + next-to-next-to-leading logarithm (NLO+NNLL) to verify the stability of our setup. We present numerical results at NLO+NNLL, which are the first complete matched predictions for energy correlators at the LHC at this order. We discuss the prospects for extensions to higher orders, outlining a path to NNLO calculations of energy correlators at the LHC.

The true nature of neutrinos–whether Dirac or Majorana–is a foundational, unresolved question. We demonstrate that the diffuse supernova neutrino background (DSNB) offers an untapped avenue to resolve this issue, provided neutrino magnetic moments are $\gtrsim 10^{-14}\mu_B$. The intense magnetic fields characteristic of a subset of collapsing massive stars can trigger resonant chirality flips. This flavor conversion physics alters DSNB fluxes in measurable ways that depend on the neutrino nature. A $20$~yr combined exposure at Hyper-Kamiokande loaded with gadolinium and JUNO can unravel this signature at $90\%$ ($99\%$) confidence if the fraction of magnetorotational events exceeds $12\%$ ($20\%$) of cosmic core collapses. This result holds independent of the mass ordering and establishes the DSNB as a critical gateway to unveiling the true identity of the neutrino.

Gravitational waves (GWs) from first order phase transitions (FOPTs) are conventionally sourced by bubble collisions, sound waves, and plasma turbulence. We propose a novel microscopic GW source arising from graviton bremsstrahlung during the decay of the scalar field driving the FOPT. In the presence of Yukawa interactions with light fermions, the scalar decay is inevitably accompanied by graviton emission due to the universal coupling of gravity to the energy-momentum tensor. We show that these gravitons generate an additional stochastic GW background during the phase-transition epoch, complementing the conventional FOPT signal. The resulting GW spectrum can exhibit a characteristic multi-peaked structure. Unlike scenarios in which different GW components originate from distinct cosmological epochs, all contributions considered here emerge from the dynamics of the same FOPT, offering a unique probe of both its microscopic particle dynamics and macroscopic plasma evolution.

In this Letter, we emphasize that asymmetries in charge flux produced in the decays of on-shell Z-bosons provide a macroscopic manifestation of electroweak anomalies in the Standard Model (SM). We propose that these can be cleanly observed using charge correlators, providing a new formulation of forward-backward asymmetry measurements that is particularly well suited for precision studies of hadronic decays. Using archival DELPHI data, we perform a first measurement of the one-point charge correlator of electromagnetic charge flux on hadrons, and cleanly observe the macroscopic imprint of the underlying anomaly. Our analysis illustrates the potential of charge correlators as precision electroweak observables, and motivates a renewed effort to resolve longstanding tensions in hadronic asymmetry measurements.

We study the sensitivity of IceCube to blazar-boosted dark matter in a fermionic dark matter model with a massive vector mediator coupling to quarks. To this aim, we compute the diffuse flux arising from a sample of 324 blazars with proton spectra inferred from multiwavelength observations, adopting conservative dark matter spike profiles around the central supermassive black holes and consistently accounting for attenuation effects during propagation through the Earth. The dark matter-nucleon scattering cross section is evaluated by including elastic, resonant single pion production, and deep inelastic contributions, with particular emphasis on resonant single-pion production channels in order to smoothly cover the transition between the elastic and deep inelastic regimes. Using IceCube neutrino data, we derive constraints on the parameter space of the model and show that this detection strategy can surpass the sensitivity of conventional direct-detection experiments for dark matter masses below $\sim 1$ GeV. We find that the signal is dominated by deep inelastic scattering and is therefore more sensitive to comparatively heavy mediators, while resonance processes provide a reduction of the event rate, reaching up to about $9\%$ near the experimental threshold. Our results demonstrate that IceCube constitutes a powerful probe of sub-GeV dark matter scenarios through the observation of blazar-boosted dark matter.

We compute the one-loop effects of vector-like fermions (VLFs) on the Higgs-strahlung cross-section, the flagship precision observable of future $e^+e^-$ Higgs factories such as FCC-ee. We consider four benchmark extensions of the Standard Model (SM): two in which a VL quark (VLQ) or VL lepton (VLL) doublet, together with its singlet partners, couples to the Higgs boson through purely internal Yukawa interactions, and two in which a single VL singlet mixes directly with the third-generation charged lepton or neutrino. Working throughout in the on-shell renormalization scheme and imposing perturbativity bounds on the relevant couplings under renormalization-group (RG) running, we compute both the universal self-energy and the non-universal vertex contributions to the Higgs-strahlung amplitude at one loop, together with the oblique parameters $S$ and $T$ and the $H\to\gamma\gamma$ rate as complementary cross-checks. In the two Yukawa-driven scenarios, we find that a sizable fraction of the parameter space still allowed by current LHC searches produces shifts in $\sigma(ZH)$ at or above the per-mille sensitivity envisioned for FCC-ee, offering a radiative probe of these couplings. In the two mixing-driven scenarios, existing electroweak-precision bounds on the relevant mixing angles already preclude an observable effect, although we characterize the underlying loop dynamics in full generality for future reference. These results identify the VL Yukawa couplings, rather than any residual mixing with the SM fermions, as the more promising target for Higgs-strahlung precision measurements at a future $e^+e^-$ collider.

Rare kaon decays provide sensitive probes of the flavour structure of the Standard Model and of possible new physics. We perform a global analysis incorporating recent experimental results and updated Standard Model predictions, including the latest measurement of $K^+ \to \pi^+ \nu\bar{\nu}$ and lepton flavour universality observables in $K^+ \to \pi^+ \ell^+\ell^-$. The fit favours a best-fit point close to the Standard Model, while a second local minimum remains phenomenologically relevant. We define benchmark scenarios associated with these two regions and investigate the prospective sensitivity of NA62 and KOTO-II to the new physics parameter space. We consider projected measurements of $K^+ \to \pi^+ \nu\bar{\nu}$ and lepton flavour universality observables in $K^+ \to \pi^+ \ell^+\ell^-$ at NA62, and of $K_L \to \pi^0 \nu\bar{\nu}$, $K_L \to \pi^0 e^+e^-$, and $K_L \to \pi^0 \mu^+\mu^-$ at KOTO-II. We find that KOTO-II has significant potential to probe and discriminate between the viable new physics scenarios, with NA62 providing complementary sensitivity.

The nature of the strangeonium-like $\phi(2170)$ remains controversial. Recent measurements of $e^+e^-\to\phi\eta^{(\prime)}$ reveal a striking puzzle: a broad $\phi(2170)$-like structure appears in the $\phi\eta^\prime$ channel but not in $\phi\eta$, despite the strong phase-space suppression of $\phi\eta^\prime$. We investigate this unexpectedly large $\phi\eta^\prime$ decay fraction within the excited-strangeonium assignment. A combined analysis of the $e^+e^-\to\phi\eta$ and $e^+e^-\to\phi\eta^\prime$ cross sections is performed by including short-distance amplitudes from vacuum quark-pair creation and long-distance transitions mediated by strange-meson loops. The short-distance mechanism predicts too small a $\phi\eta^\prime/\phi\eta$ strength ratio to explain the data. In contrast, strange-meson loops naturally enhance this ratio because the SU(3)-flavor factor at the $K^{(*)}K^{(*)}\eta^{(\prime)}$ vertex suppresses the transition to $\phi\eta$ relative to $\phi\eta^\prime$. The resulting overall description of both cross sections supports an important role for long-distance dynamics in hidden-strangeness decays of excited vector strangeonia. More intriguingly, although the excited strangeonium contributions have been included, the current high-precision $\phi\eta$ data still favor the existence of an extra narrow vector state near $2.15~\mathrm{GeV}$ with a width of about $25~\mathrm{MeV}$. If confirmed, it would be a promising exotic-hadron candidate in the light-vector sector. Furthermore, we test $\Gamma(Y\to\phi\eta)/\Gamma(Y\to\phi\eta^\prime)=0.25$, $1$, and $4$ as fit inputs and obtain similarly good descriptions of the cross sections in all three cases. The present data therefore do not allow this ratio to discriminate among different internal configurations of the narrow state.

Triboson production processes are crucial to study quartic gauge-boson couplings. We present the computation of the radiative corrections to $WW\gamma$ production at the next-to-next-to-leading order (NNLO) in QCD. The leptonic decays of the $W$ bosons and off-shell effects are fully included. The calculation is exact, apart from the finite part of the two-loop amplitudes, which is evaluated in a soft-photon approximation. We validate our approach by using $Z\gamma$ production as a reference process, where we take advantage of the availability of the exact two-loop amplitudes to derive a conservative error estimate for our approximation, and then apply it to $WW\gamma$ production. For typical selection cuts, at the centre-of-mass energy $\sqrt{s}=13$ TeV, the NNLO corrections increase the next-to-leading order (NLO) result by about $16\%$, and the perturbative uncertainties are reduced to the $\pm4\%$ level. The uncertainty from the soft approximation turns out to be at the few per mille level, largely subdominant compared to the residual perturbative uncertainties, both for the fiducial cross section and the most relevant differential distributions.

We discuss the factorization of scattering processes near partonic threshold at next-to-leading power (NLP) in the threshold variable $1-z$, with $z \equiv q^2/\hat{s}$. We review the general structure of power-suppressed contributions both in Soft-Collinear Effective Theory (SCET) and in a direct QCD approach, and discuss the definition of NLP jet functions as gauge-invariant operator matrix elements in QCD. As a controlled check of the resulting factorization formula, we verify it explicitly at one and two loops for the massive electromagnetic form factor in the limit $m^2 \ll s$, using the method of regions. We conclude by outlining the two challenges that remain for a systematic resummation of NLP logarithms: the treatment of endpoint divergences in SCET convolutions, and the extension of jet functions to radiative processes capable of describing an arbitrary number of soft-gluon emissions – the latter being the last missing ingredient for exponentiation, given that the purely soft sector is already understood in terms of generalised webs via the replica trick.

For a spin-zero meson, the exact trace identity relates the D term to the tensor gravitational form factor $A_M(t)$ and the total scalar trace $\Theta_M(t)$. We study the pion and kaon D terms by combining a holographic tensor form factor with a chiral-dispersive representation of the trace. Its normalization and slope at the origin are obtained from the forward Ward identity and curved-space SU(3) chiral perturbation theory. A two-channel $\pi\pi/K\bar K$ Muskhelishvili–Omnès solution constructed from empirical scattering amplitudes describes the continuation to spacelike momentum. Available lattice-QCD results are shown for comparison. In the chiral limit, saturation of the trace by the normalized explicit quark-mass response gives $D_\pi(0)=-1/3$, while the soft-pion theorem gives $D_\pi(0)=-1$. This comparison separates the explicit-mass contribution from the remaining chiral scalar response. At physical masses, SU(3) breaking in the chiral matching distinguishes the pion and kaon forward values, and coupled-channel rescattering governs their evolution away from the origin. The kaon D term is less negative than the pion result in the low-$Q^2$ spacelike region considered, with the separation decreasing as $Q^2$ increases. These form factors provide a low-energy reference for future lattice studies of the tensor and scalar channels.

We compute for the first time the subleading twist correction to the exclusive rare $b \to \left \{s, d \right \} \ell^{+} \ell^{-}$ decays from the three-particle $B$-meson distribution amplitude at next-to-leading order accuracy by employing the soft-collinear effective theory. This constitutes the last missing ingredient for the complete factorization analysis of the hadronic matrix element of the weak effective Hamiltonian at leading power in the heavy quark expansion. Incorporating further a variety of the next-to-next-to-leading-order QCD corrections to the spectator-scattering amplitude and the weak annihilation topology, we then present the improved field-theoretic predictions for phenomenologically interesting observables in the electroweak penguin $B \to \left \{K, \pi \right \} \ell^{+} \ell^{-}$ decays.

We present Pairton, an iterative framework for reconstructing short-lived particles in high-energy collision events. By formulating particle reconstruction as a masked prediction process over graph structures, Pairton learns conditional distributions consistent with a factorised decomposition of decay products and iteratively predicts edges in the adjacency matrix representing particle decay relationships. Leveraging a pairformer-based architecture with dynamically updated pairwise representations, our method incorporates global event consistency. We demonstrate state-of-the-art performance on fully hadronic $t\bar{t}$ decays. Pairton provides a general, flexible paradigm for particle reconstruction and can be readily extended to other topologies, bridging ideas from modern generative modelling and high-energy physics.

For fixed Standard Model (SM) non-Abelian representations of 15 chiral fermions with arbitrary hypercharges, anomaly cancellation admits the usual assignment and a distinct nonstandard solution. In the latter, the colored exotic quark and exotic lepton weak doublets and exotic lepton singlet have zero hypercharge, whereas the two colored exotic quark singlets carry opposite hypercharges $-q$ and $q$. The exotic neutral lepton singlets naturally play the role of the heavy neutrinos. The minimal model with two exotic lepton copies gives a rank-two seesaw, the minimal seesaw model, with one massless active neutrino and predicts $m_{\beta\beta} = 1.2 \text{-} 4.1 \, \mathrm{meV}$ for normal ordering or $15.9\text{-}48.9 \,\mathrm{meV}$ for inverted ordering. In a direct SM realization, generating exotic quark masses through the SM Higgs mechanism forces the exotic quarks to carry electric charges $\pm 1/2$. A separate $\mathrm{SU}(2)_{L'}$ realization of the nonstandard solution can allow exotic quarks from several TeV to $10\,\mathrm{TeV}$ with order-one Yukawa couplings. In this model, the charged exotic quarks and leptons carry electric charges $\pm q$. In both cases, the lightest exotic quark and lepton are stable, but suitable choices of their charges and masses can satisfy experimental constraints.

The simultaneous production of a $W^\pm$ boson and a charmed hadron in proton-proton collisions offers a potential probe for constraining the strange quark parton distribution functions (PDFs). We study these processes at next-to-leading order in perturbative Quantum Chromodynamics within the general-mass variable-flavor-number scheme. By considering ratios of cross-section between oppositely charged mesons, uncertainties associated with unphysical scale choices and fragmentation functions are shown to effectively cancel out, leaving the uncertainty originating from the PDFs as the dominant one. By comparing our calculations with CT18A, MSHT20 and NNPDF4.0 PDFs with the recent ATLAS measurement at $\sqrt{s} = 13\,{\rm TeV}$ we find that CT18A, which imposes zero strangeness asymmetry, agrees best with the data, while MSHT20 and NNPDF4.0, both of which allow for a non-zero strangeness asymmetry, exhibit greater tension with the ATLAS data. The sensitivity to the strangeness asymmetry is further confirmed by the PDF reweighting methods. We also study the impact of possible intrinsic charm content of the proton finding no significant sensitivity. Finally, we explore the possibility of measuring these processes in proton-lead collisions. With the estimated detector efficiencies and projected luminositites at the high-luminosity LHC, these processes should be visible, yet with a rather limited constraining power for nuclear PDFs.

The asymptotic symmetry group of asymptotically flat spacetimes gives rise to balance flux equations that constrain, fully non-perturbatively, the asymptotic strain measured by gravitational-wave detectors. Such constraints are sharp tools for identifying features such as the memory effect. As detector sensitivities improve, it becomes imperative to place the most promising beyond-GR candidates on the same footing. Whether the asymptotically flat framework applies to such theories at all is far from obvious and requires careful analysis of the additional degrees of freedom reaching future null infinity. In this work, we address this question. We integrate the Bondi-Sachs hierarchy in the presence of an arbitrary stress-energy tensor and extract the falloff conditions its components must satisfy for the standard metric decay to close. We then feed the most general scalar-vector-tensor (SVT) theory with second-order equations of motion through this framework. Recasting the field equations in the effective Einstein form $G_{\mu\nu}=T^{\rm eff}_{\mu\nu}/G_4(\Phi,X)$ and evaluating every operator in the SVT Lagrangian against the falloff table, we condense the outcome into a constraint table for the coupling functionals and their derivatives at the asymptotic vacuum, sharpened by the additional equations of motion and vacuum stability. Remarkably few conditions survive. The scalar potential must vanish to cubic order at the asymptotic vacuum, the asymptotic Newton constant must be finite and positive, the scalar and vector modes must be canonically normalized, and the conformally coupled sector carries a frame subtlety. Every other coupling functional is protected by the theory's structure. The constraint table thus provides a diagnostic for screening beyond-GR models against asymptotic flatness and establishes the BMS group as the asymptotic symmetry group across the entire SVT class.

We study the single production of first-generation weak-isosinglet vector-like leptons (VLLs) at future $e^+e^-$ colliders, considering the channels $e^+e^- \to e^{\pm}E^{\mp}$ with $E^{\pm} \to W^{\pm}\nu_e$ and $E^{\pm} \to e^{\pm}Z$. For the heavy VLL masses under consideration, the decay products of the highly boosted $W$ and $Z$ bosons merge into a single fat-jet, providing a powerful handle for signal identification and background suppression. A comprehensive Monte Carlo simulation is carried out at $\sqrt{s}=1$ TeV at the International Linear Collider (ILC) and 1.5 TeV at the Compact Linear Collider (CLIC). The $2\sigma$ exclusion and $5\sigma$ discovery reaches are determined as functions of the integrated luminosity and the mixing parameter $\sin\theta_L$ for representative benchmark masses. Our results show that future $e^+e^-$ colliders can effectively probe the first-generation singlet VLL scenario through these channels. The 1 TeV ILC can probe masses up to 900 GeV, while the 1.5 TeV CLIC extends the reach to 1400 GeV, surpassing existing limits from hadron colliders and complementing constraints from electroweak precision measurements.

Fermionic field types in arbitrary signature are often inferred from complex Spin representations alone, which obscures distinctions associated with real structures, disconnected spacetime reflections, and action-level bilinear constraints. We give a convention-explicit classification that treats the full real Clifford algebra and its even subalgebra separately, thereby distinguishing pinors from spinors and Pin-equivariant Majorana-type structures from structures that are only Spin-equivariant. Adjoint, complex-conjugation, and transposition intertwiners are combined with elementary and collective reflection lifts into a unified sign calculus. The resulting local Clifford classification is organised into thirty-two periodicity sectors determined by the Bott class and the total dimension modulo eight, without including theory-dependent gauge, anomaly, or global constraints. For each sector, we identify the available Dirac, Weyl, Majorana, symplectic Majorana, Majorana-Weyl, and symplectic Majorana-Weyl fields. The existence of an invariant pairing is distinguished from intertwiner compatibility, Grassmann and chiral selection rules, covariant index contraction, and Hermiticity of local bilinear operators.

High-energy heavy-ion collisions have the potential to create local domains of chirality-imbalanced quarks, reflecting the topological characteristics of quantum chromodynamics. This phenomenon can potentially induce local $\mathcal{P}$ and $\mathcal{CP}$ violations in the quark-gluon plasma. The Chiral Magnetic Effect (CME) predicts an electric charge separation along the intense magnetic field generated during these collisions, which is typically investigated through charge-dependent azimuthal correlations ($\Delta\gamma$). In this work, we investigate the CME in Au+Au collisions at $\sqrt{s_{NN}} = 7.7 - 200$ GeV using a multiphase transport (AMPT) model equipped with a Chiral Anomaly Transport (CAT) module. we employ two independent methods: direct subtraction of the correlator $\langle N_{part}\Delta\gamma\rangle$ between simulations with zero and finite chiral chemical potential $\mu_5$, and the event-shape-selection (ESS) approach. Our results reveal a significant CME signal within the energy range of 11.5-27 GeV and the centrality range of $20-50\%$, where the AMPT model aligns well with STAR experimental data. Furthermore, the CME fractions extracted by both methods are consistent within uncertainties across these energies. However, the CME signal disappears at both 7.7 and 200 GeV. These findings underscore that the observability of the CME critically depends on both the dynamic evolution of the magnetic field and the chemical freeze-out time of the partonic phase, which vary significantly with collision energy.

Experimental searches for fully heavy tetraquark states are actively pursued at the LHC. The LHCb, CMS, and ATLAS collaborations have investigated fully charmed $cc\bar{c}\bar{c}$, mixed $bc\bar{b}\bar{c}$, and fully bottom $bb\bar{b}\bar{b}$ tetraquarks. In particular, narrow structures such as $X(6200)$, $X(6900)$, and $X(7300)$ observed in the di-$J/\psi$ mass spectrum have stimulated considerable theoretical interest. We employ a nonrelativistic diquark-antidiquark model to investigate the mass spectra of ground ($1S$) and excited ($1P$, $2S$, $1D$, $2P$, $3S$, and $4S$) fully heavy tetraquark states. The tetraquarks are modeled as color-singlet bound states of axial-vector diquarks and antidiquarks in the $\mathbf{\bar{3}}$ and $\mathbf{3}$ color representations. The Schrödinger equation is solved numerically using a modified Cornell potential and the three-point central difference method, while spin-dependent interactions are treated nonperturbatively. We investigate a broad range of $J^{PC}$ quantum numbers for $S$-, $P$-, and $D$-wave states. The predicted masses are compared with recent LHC observations and other theoretical calculations, and the stability of the states against strong fall-apart decays is examined. Our results support the interpretation of several observed structures as different excitations of fully charmed tetraquarks and provide useful predictions for their experimental identification.

We develop a neural-network maximum-entropy (NN+MaxEnt) framework for reconstructing probability distributions from limited observables in heavy-ion collisions. The method combines flexible neural-network representations with Shannon-entropy regularization, preserving positivity and normalization without assuming a fixed analytic form. After validation with Gaussian, Poisson, and mixed-Poisson closure tests, we apply the framework to two physics-motivated inverse problems: an effective multiplicity reconstruction constrained by functional renormalization group cumulants, used as a closure test, and the conditional jet-energy-loss distribution extracted from single-inclusive jet $R_{AA}$ data in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$~TeV. For the fRG closure test, NN+MaxEnt accurately reproduces the imposed cumulants and yields distributions consistent with conventional MaxEnt solutions. For jets, the reconstructed energy-loss distributions reproduce the measured $R_{AA}$; at an initial jet momentum $x=50~\mathrm{GeV}$, the conditional mean energy loss is $\langle\Delta p_T\rangle\simeq11.8~\mathrm{GeV}$, with a central $16\text{--}84\%$ interval of $9.0\text{--}15.0~\mathrm{GeV}$. The extracted energy-loss profile is qualitatively consistent with Bayesian MCMC and LBT results. NN+MaxEnt thus provides a flexible, less ansatz-dependent framework for regularized distribution reconstruction from observables connected to the underlying distribution through differentiable forward maps.

We propose the Inference-driven Participant Determination (IPD) method, a Bayesian framework for inferring event-by-event posterior distributions of the number of participants ($N_{\text{part}}$) and binary collisions ($N_{\text{coll}}$) from final-state charged-particle multiplicities in relativistic heavy-ion collisions. The joint distribution of $(N_{\text{part}}, N_{\text{coll}})$ obtained from the Monte-Carlo Glauber model is used as the prior, while negative binomial distributions calibrated to charged-particle multiplicity fluctuations define the likelihood. This approach replaces conventional hard-cut centrality classification with a probabilistic assignment based on $N_{\text{part}}$, making the multiplicity–geometry smearing explicit and reducing the impact of volume fluctuations on downstream observables. A closure test using an UrQMD-MCG hybrid model at $\sqrt{s_{NN}} = 19.6$~GeV shows that the method yields well-calibrated posterior distributions with negligible bias and improves the reconstruction of net-proton cumulants relative to conventional multiplicity-based centrality selection.

The strong $\mathcal{CP}$ problem and quark mass hierarchies can probe the same ultraviolet structure. We show this by extending modular strong-$\mathcal{CP}$ solutions to non-Abelian finite modular symmetries. This reveals a previously overlooked modular-anomaly condition from the finite representations. Regularity removes the dependence of the QCD angle on the $\mathcal{CP}$-breaking modulus, yielding $\bar\theta=0$. For positive modular weight, it also forces the quark Yukawa determinant to vanish at the cusp. This leads to pronounced mass hierarchies among the quarks. We further stress that modular symmetries act as R-symmetries. Under moderate additional assumptions, this renders the QCD angle independent of the dilaton. An explicit model illustrates the mechanism.

Conventional wisdom says that neutrino oscillations measure only mass-squared differences and not the absolute neutrino mass scale. This is true, however, only at leading order in the expansion parameters $m_i/E$, the ratios of the neutrino masses $m_i$ ($i=1,2,3$) to the neutrino energy $E$. At next-to-leading order, the oscillation phase includes terms proportional to $m_i^4-m_j^4 = \Delta m^2_{ij}(m_i^2+m_j^2)$, and is therefore sensitive to the absolute mass scale. In this paper, we derive the next-to-leading-order corrections using a wave-packet treatment and taking into account the neutrino-production kinematics. We then apply this result to reactor antineutrinos and find that the JUNO experiment is sensitive to neutrino masses of a few hundred keV. While not competitive with existing bounds from beta decay, electron capture, and cosmology, neutrino oscillations provide a novel, complementary probe of the neutrino mass scale, with sensitivity to a different combination of neutrino masses.

We consider a simple model-independent extension of the minimal KSVZ axion model, augmenting the Peccei - Quinn effective potential with a dimension-6 operator invariant under the Peccei - Quinn symmetry. We show that this operator can trigger a first-order phase transition and study its cosmological consequences. We map out the parameter space, consistent with present observational constraints, in which the phase transition produces a gravitational wave signal observable at current and future interferometers, and we investigate the resulting dark matter phenomenology. Finally, we present specific ultraviolet completions that generate the dimension-6 operator, each leading to distinct phenomenological signatures, which motivates our model-independent approach.

Hamiltonian truncation offers a nonperturbative route to quantum field theory, yet its accuracy is limited by the rapid expansion of the truncated Hilbert space, which drives up computational cost. We tackle this bottleneck with a hybrid strategy that pairs classical and quantum algorithms: 1) we develop an efficient basis-generation scheme built on integer partitions; 2) we speed up the construction of the sparse Hamiltonian matrix using symmetry-aware algorithms; and 3) we explore quantum Krylov diagonalization as a route to the low-lying spectrum. Benchmarking against the free massive scalar and $\phi^4$ theories in two spacetime dimensions, we achieve substantial gains in the computational efficiency of Hamiltonian truncation and chart a path toward future quantum implementations.

Generic event-level anomaly detection for collider physics has two recurring problems: anomaly scores are hard to interpret, and they correlate strongly with energy scale and object multiplicity. We present Organized Representation via Contrastive learning for Anomaly detection (ORCA), a two-stage framework that first learns an embedding space via supervised contrastive learning across a diverse set of physics processes, then runs a standard autoencoder in that space to generate event-level anomaly scores. On a simulated dataset consistent with conditions at the High-Luminosity Large Hadron Collider, ORCA delivers significant gains in both breadth and depth of sensitivity to new physics signals with respect to a baseline autoencoder architecture. Beyond improved sensitivity, the contrastive embedding makes the anomalous sample interpretable: because known processes occupy distinct regions of the space, a maximum-likelihood template fit to the embedding distributions can attribute events in an anomalous sample to template physics processes with quantified uncertainties. We demonstrate that the fit accurately recovers injected signal yields, including for signals excluded from the training of the embedding, and characterizes signals absent from the template library through the known processes they most resemble. These results establish ORCA as a route to interpretable anomaly detection-based searches at colliders, where the embedding geometry carries higher dimensional physics information compared to standard one-dimensional output fits, enhancing downstream statistical analysis.