Papers

Within the heavy-mass expansion, the pole width of a system containing one unstable heavy constituent inherits the constituent width up to $\mathcal O(\Lambda_{\rm kin}^2/m_Q^2)$ corrections, while radial splittings remain $\mathcal O(\Lambda_{\rm rad})$. The top quark is an extreme realization of this hierarchy. We implement the complex top pole mass in an instantaneous Bethe–Salpeter framework, where a biorthogonal Hellmann–Feynman relation realizes width inheritance at the operator level and an artificial heavy-mass scan confirms the predicted $m_Q^{-2}$ suppression. The low-pole source-projected response has a single broad maximum at the physical top width in the $t\bar b$, $t\bar c$, and $t\bar u$ channels. Full width-dependent non-Hermitian re-diagonalization and a direct full-matrix resolvent evaluation confirm the progressive dissolution of the small-width radial maxima. Thus stable-top eigenvalues survive as reference poles but not as a resolvable multi-peak spectrum; they may instead leave qualitative, process-dependent $Wb\bar q$ signatures, such as a broad threshold enhancement or modified color flow.

We calculate the electromagnetic form factors of nucleons bound in finite nuclei and make predictions to the ratio between the electric ($G_E^*$) and magnetic ($G_M^*$) form factors in terms of the square of the four-momentum transfer $Q^2$. We extend our previous constant-density calculations within the covariant spectator-QMC framework by incorporating the spatial nuclear density profiles of finite nuclei and quantify the deviations from the average-density approximation used in our previous applications. The impact of the medium effects can then be observed considering the ratio between $G_E^*/G_M^*$ and the ratio in free space $G_E/G_M$, that define the proton electromagnetic double ratio associated with a given nucleus. The double ratio is expected to remove some systematic uncertainties. There is the expectation that ratios $G_E^*/G_M^*$ associated with the bound protons inside the nucleus will be measured in the near future in polarization-transfer experiments $(\vec{e} A, e'\! A' \vec{p})$. Anticipating future measurements on the subject, we make predictions for the double ratios, to be compared with the average measurements on the energy states of protons bound to nuclei. We consider the nuclei $^{12}$C, $^{16}$O and $^{40}$Ca. We conclude that the form factors calculated using nuclear density profile function $\rho(r)$ are less suppressed than in the case of the results calculated using the average nuclear density. The results indicate that the relative importance of the low-density surface region increases with $Q^2$, leading to a weaker suppression than that predicted by the average-density approximation. We also make predictions for the ratios associated with neutrons bound to nuclei.

The ultra-compressed scotogenic regime, in which a 2\,GeV mass splitting between the charged inert scalar and the dark-matter fermion is motivated by and compatible with co-annihilation to the observed relic density for suitable choices of the remaining model parameters, produces decay leptons for which existing LHC displaced-lepton and disappearing-track searches retain only partial, unoptimised acceptance, leaving room for a dedicated timing-assisted strategy. We propose exploiting the 30\,ps timing resolution of the HL-LHC precision timing detectors as a fourth observable, converting the macroscopic scalar decay length of 100–1000\,mm into an arrival-time delay of 70–700\,ps—more than three orders of magnitude above the sub-picosecond delays of all prompt Standard Model backgrounds. Operating at the level of a low-$p_T$ disappearing-track stub matched to a delayed timing hit, without requiring full lepton reconstruction, our 4D timing strategy achieves signal efficiencies of 12–36% across the probed mass range (14% at the 200\,GeV benchmark) and zero background across $4.20\times10^6$ simulated prompt SM events, projecting 95%\,C.L.\ exclusion up to scalar masses of $\simeq\!670$\,GeV at 3000\,fb$^{-1}$ under conservative background assumptions. The scalar lifetime is set by the Yukawa coupling $y$ through $c\tau\propto y^{-2}$, while sub-eV neutrino masses constrain only the product $y^2\lambda_5$; the small couplings that place the charged scalar in the optimal timing window are therefore compatible with, though not uniquely fixed by, the radiative neutrino-mass mechanism, making the co-annihilation corridor—conventionally the most elusive regime—an accessible target for 4D spacetime tracking at the HL-LHC.

When irreducible representations occur with multiplicity, a family symmetry fixes the representation content of a Yukawa sector but need not fix its embedding in the space of generation tensors. We study the spectral consequences of this additional embedding data for complex-symmetric three-family tensors with the $S_3$ assignment $V=\mathbf{1}\oplus\mathbf{2}$. Since $\operatorname{Sym}^2V=2\,\mathbf{1}\oplus2\,\mathbf{2}$, three-dimensional invariant Yukawa subspaces of type $\mathbf{1}\oplus\mathbf{2}$ form a continuous $\mathbb{CP}^1\times\mathbb{CP}^1$ family, denoted $\mathcal L_{t,\kappa}$ on a finite affine chart. On the $\kappa=0$ branch, we solve the inverse singular-value problem and obtain necessary and sufficient conditions for any prescribed ordered positive mass spectrum. A fixed singlet embedding imposes a finite hierarchy bound, whereas varying the embedding accommodates every positive three-family spectrum. For general embeddings, $\mathcal L_{t,\kappa}$ contains a nonzero rank-one matrix if and only if $2t\kappa^2=1$; equivalently, these are precisely the finite-chart embeddings for which $\sigma_3/\sigma_2$ is unbounded. In a conventional complex-symmetric $S_3$ three-Higgs sector, the same condition becomes $y_2y_5^2=\sqrt{2}\,y_1y_3^2$, so order-one Yukawa coupling ratios can support arbitrarily large mass hierarchies. We then apply the result to a recent Clifford-algebraic construction and show that its family-resolved Yukawa tensors span $\mathcal L_{2,0}$, whose singular values obey $m_1+m_2\leq m_3\leq m_1+3m_2$. This excludes the observed charged-lepton hierarchy for arbitrary complex vacuum alignment within the existing Higgs directions. The resulting obstruction is therefore tied to the fixed multiplicity embedding rather than to the $S_3$ representation content alone.

Models where an axion-like inflaton is coupled to a $U(1)$ gauge field are theoretically well motivated and can display a rich phenomenology. The regime in which the quanta of the gauge field strongly backreact on the rolling inflaton has been studied for well more than a decade, and yet we cannot say that it is fully understood. In this paper we present an analytical study of the onset of the strong backreaction regime. Our formalism relies on a Laplace transform to convert a complicated integro-differential equation into the search of the poles of an analytic function. We confirm the existence, previously observed using a completely different formalism, of a stable region of strong backreaction. Our work provides, for the first time, analytical formulae that allow to study the evolution of the system as it transitions from the weak to the strong backreaction regime.

We investigate the sensitivity of DUNE-like facilities to flavor-changing neutral-current interactions between down and strange quarks through inclusive deep-inelastic neutrino scattering. In the framework of a general low-energy effective Lagrangian for Dirac and Majorana neutrinos, we evaluate projected sensitivities for CP- and $\tau$-optimized beam configurations. The strongest bounds on the dimensionless Wilson coefficients, defined relative to the Fermi constant $G_F$, reach $\mathcal{O}(10^{-3})\text{--}\mathcal{O}(10^{-2})$ at the near detector, whereas far-detector limits are roughly one order of magnitude weaker. When systematic uncertainties are included, the near-detector sensitivity is dominated by the background-rate uncertainty, while the far-detector sensitivity is limited primarily by the signal-rate uncertainty. At the far detector, the dependence of the projected bounds on the neutrino mass ordering and the Dirac CP-violating phase $\delta_{\mathrm{CP}}$ is largely confined to coefficients involving the electron flavor.

We present a comparative study of the influence of Wilson coefficients on Higgs boson pair production cross sections in SMEFT up to dimension-6, also including loop-suppressed operators. Our study accounts for NLO QCD corrections, and is based on updated parametrizations of the cross section as a polynomial in the Wilson coefficients. We focus on differential distributions for the Higgs boson pair invariant mass, as well as the transverse momenta of the leading Higgs bosons, identifying benchmark scenarios exhibiting pronounced shape distortions in the $m_{hh}$ and $p_{T,h}$ distributions. While some of these scenarios remain physically meaningful under a purely linear truncation of the SMEFT expansion, others yield unphysical differential cross sections when quadratic dimension-6 contributions are omitted, exposing the breakdown of the linear approximation for large anomalous couplings.

We present FTFT (Fixed-Target Fragmentation Tune), a set of Pythia8 parameters optimised for the production of charm and beauty hadrons in fixed-target collisions at centre-of-mass energies $\sqrt{s} \simeq 20-42$ GeV. Accurate heavy-flavour production in this regime is needed to predict neutrino fluxes and hidden-particle yields at beam-dump experiments such as SHiP. The tune is derived in two stages. First, differential distributions in Feynman-$x$ ($x_F$), transverse momentum squared ($p_T^2$), and charge or leading-particle production asymmetry of $D$ mesons are fitted to data from pion- and proton-beam fixed-target experiments. Second, $K$-factors for each beam are extracted from inclusive charm cross-section measurements to scale the simulated cross section to the measured data. The fitted charm-fragmentation and multiparton-interaction parameters depart from standard LHC-tuned defaults, in line with earlier fixed-target studies.

We investigate primordial black hole formation in a Dirac-Born-Infeld inflationary framework in which the background dynamics are determined by explicit functional forms of the inflaton potential $V(\phi)$ and the warp factor $f(\phi)$. The background equations are solved numerically to obtain the evolution of the slow-roll parameters. We show that a localized feature in the potential, accompanied by a correlated structure in the warp factor, dynamically induces a transient suppression of the slow-roll parameter, leading to a short-lived non-attractor phase. This behavior generates an enhancement of the curvature power spectrum on small scales, while preserving consistency with CMB-scale observables. The Mukhanov-Sasaki equation is then solved numerically to compute the resulting power spectrum, which exhibits narrow and localized peaks in the PBH abundance across different mass ranges. We also evaluate the associated stochastic background of induced gravitational waves and find that the predicted signal can fall within the sensitivity bands of future pulsar timing arrays and space-based interferometers, depending on the scale of the inflationary feature. A parameter scan in the $(r,n_s)$ plane shows that the large-scale predictions remain consistent with current observational constraints.

We point out that a non-invertible selection rule can control the flavor violation inherent in lepton portal dark matter, a weakly interacting massive particle candidate that can evade severe constraints from direct detection experiments. We show that ordinary invertible symmetries cannot suppress flavor-violating portal couplings while accommodating the large mixing angles in the PMNS matrix. We then present a simple construction based on the $\mathbb{Z}_2$ gauging of a $\mathbb{Z}_5$ symmetry, which realizes one-flavor dominance of the portal couplings consistently with the PMNS mixing matrix. We also discuss possible flavor leakage in a type-I seesaw completion and study experimental probes of the model through lepton observables, especially lepton flavor non-universality in $Z$ boson decays.

Light-cone distribution amplitudes (LCDAs) are essential to precision phenomenological studies. They can be accessed from lattice QCD through the large-momentum effective theory (LaMET) via quasi-distribution amplitudes (quasi-DAs). Factorization of quasi-DAs receive power corrections in inverse powers of the hadron momentum, including target-mass and higher-twist corrections. In this work, we present the first systematic analysis of such power corrections for the leading-twist baryon quasi-DA. Establishing the moment relation between the quasi-DA and the LCDA, we derive an exact closed-form relation that resums target-mass correction to all orders at leading twist. This result also applies to heavy baryons and to quasi-transverse-momentum-dependent distributions. We numerically assess these corrections for the $\Lambda$ baryon quasi-DA using existing lattice data, finding that the target-mass correction decreases rapidly with increasing baryon momentum and is almost negligible in the endpoint regions. In addition, we explicitly construct the next-to-leading-twist operators entering the quasi-DA factorization. Our results are a first step toward quantifying the power corrections in future lattice determinations of light or heavy baryon LCDAs.

Triangle singularities, predicted by Landau in 1959, are purely kinematic enhancements arising from hadronic rescattering loops. Despite their proposed role in various anomalous decay processes and exotic hadron candidates, a direct experimental confirmation has remained elusive for more than six decades. We analyze the $p\eta/\bar{p}\eta$ invariant mass spectrum in $\psi(2S) \to p\bar{p}\eta$ measured by the BESIII Collaboration. The data exhibit a clear cusp-like structure around 1.564~GeV in the $N(1535)$ region, in precise agreement with the kinematic position predicted for the triangle singularity. Including the triangle singularity loop in the fit substantially improves the description of the data, with $\chi^2/\mathrm{d.o.f.}$ decreasing from 1.22 to 0.90, corresponding to a significance of $\sim 3.8\sigma$ for the triangle singularity contribution. The precise alignment of the observed excess with the predicted kinematic position provides the first compelling evidence for the triangle singularity effect.

In the semi-constrained NMSSM at large lambda and low tan(beta), di-Higgs production can proceed through h1h1 -> 4a1 -> 8tau when the lightest pseudoscalar lies below the b-bbar threshold. The tau pairs from each a1 decay are collimated and merge within a single jet. Using the benchmark point m_a1 = 8.2 GeV identified in earlier work as a representative signal topology, we examine which observables separate such events from Standard Model processes producing similar final states. The exotic branching fraction of this point exceeds present experimental limits, and all results concern the shape of the distributions, not the signal rate. The substructure observables normally used for two-prong tagging prove ineffective here: the jet mass and the N-subjettiness ratio tau_21 have separation powers of 0.02 and 0.09 against boosted Z -> tau tau. Both are ditau jets, and the neutrinos from tau decays displace the reconstructed masses to a common value near 18 GeV despite parent masses differing by an order of magnitude. Discrimination comes instead from the event as a whole. A boosted decision tree trained on single fat jets reaches an AUC of 0.759 +- 0.002, while an event-level classifier reaches 0.941 +- 0.001, driven by the multiplicity of boosted objects and the masses of the subleading ones. Top-quark pair production reproduces the multi-object structure, and against ttbar -> bbbar tau tau the AUC falls to 0.855 +- 0.008. For a cross-section-weighted combination of the two simulated backgrounds the classifier reaches 0.908 +- 0.002, with 71% signal efficiency at 10% background efficiency. These are classification metrics from fast simulation, not discovery significances.

Inverse Compton sources — in which a relativistic electron beam scatters a laser pulse to produce tunable, collimated, high-energy radiation — have emerged as promising compact radiation sources, with applications in nuclear photonics, medical imaging, and nanoscale metrology. As laser intensities increase and electron energies grow, the interaction enters the radiation reaction regime, where the energy radiated by the electron becomes a significant fraction of its kinetic energy. Predicting the scattered electron energy spectrum from first principles has remained an unsolved problem. Existing models are either classical equations of motion requiring large-scale multiparticle simulation, or quantum models relying on approximations of uncertain validity with the same simulation burden. None directly produce a spectral prediction. This dissertation presents a novel framework that resolves this deficiency. The laser pulse is represented as a coherent quantum state of the electromagnetic field and the electron beam as a statistical quantum state encoding its momentum distribution — the natural realization of particle-field scattering within quantum electrodynamics. For a Gaussian laser pulse, a closed-form analytic expression for the scattered spectrum is derived requiring no simulation, no approximation of the laser field profile, and no large particle ensembles. The classical limit recovers Landau-Lifshitz dynamics exactly, establishing the coherent-state model as the quantum electrodynamic realization of classical radiation reaction theory. The framework is validated against existing experimental data, and fundamental structural limitations of all current modeling approaches are identified and analyzed.

The Schrodinger equation in one spatial dimension admits a small set of exactly solvable potentials that serve as natural proving grounds for any new eigenvalue solver. We formulate Physics-Informed Neural Networks (PINNs) and Physics-Informed Quantum Neural Networks (PIQNNs) for the time-independent Schrodinger equation and apply them to three of these benchmarks: the harmonic oscillator, the infinite square well, and the finite square well. In each case a composite loss encodes the differential-equation residual, the normalization condition, the boundary behavior, and the orthogonality between eigenstates, so that the trial wave function is driven toward a genuine eigenfunction without supervised data. The eigenvalues and wave functions returned by both methods are compared against the exact spectra and against three classical references: the matrix Numerov method, the finite difference method, and the shooting method. For the smooth oscillator the two neural solvers reproduce the lowest four eigenvalues to parts per million, while for the square wells they recover the analytic levels with comparable fidelity even where the potential is discontinuous. The quantum circuit, built as a layered angle-embedding ansatz with strongly entangling blocks, converges more reliably than its classical counterpart on the higher excited states, where the loss landscape of the classical network becomes harder to navigate.

Two track-like events with exceptionally large charge deposits, pointing back to the region of maximum overburden ($>18$ km.w.e.) of the Pico de Orizaba volcano, were reported by the HAWC Collaboration in a search for Earth-skimming neutrinos. Using exclusively published information, including the published Monte Carlo charge distributions and the scattered-muon background model, we show that these events are kinematically inconsistent with all identified backgrounds. A conservative energy-conservation bound places the in-tank energy deposit of the candidates above $\approx$190–210~GeV, with a worst-case minimum of 122–136~GeV, in either case exceeding the 100~GeV maximum of the scattered-muon background model. Calibration systematics derived from the published simulations act unidirectionally, pushing the implied deposits into the multi-TeV regime. Direct atmospheric muons require $E_\mu \gtrsim 0.67$~PeV to penetrate the overburden and contribute $4.5\times10^{-5}$ expected events ($\lesssim 10^{-3}$ under the largest possible prompt-charm flux); collinear muon bundles are excluded by five independent arguments. Conversely, the neutrino hypothesis predicts identifiable events precisely in the observed charge window ($10^{3}$–$10^{4}$ photoelectrons) and in the highest-overburden analysis region, both observed. The two track-like events imply a rate that exceeds the conventional atmospheric neutrino flux expectation at the 2.1–2.5$\sigma$ level. The charges of the observed candidates require an emerging lepton above about 20~TeV; the published calibration does not bound the energy from above. These would constitute the first neutrino candidates detected in Mexico and the first obtained with the Earth-skimming volcano technique.

The discovery of the strongly-coupled quark-gluon plasma (sQGP) in high-energy heavy-ion collisions has revealed remarkable properties of matter at high temperature, with transport coefficients close to conjectured bounds from quantum field theory at strong coupling. The high sQGP collision rates imply very large energy uncertainties and the melting of quasiparticle structures. Deploying quantum many-body theory based on the self-consistent $T$-matrix approach for the sQGP at high temperature, we investigate its manifestation at high baryon density and low temperature, as present in neutron stars and their mergers. We constrain the chemical-potential dependence of the quark interaction kernel using first-principles information from Quantum Chromodynamics on baryon-number susceptibilities. Very large collisional widths persist at large density and are found to relegate superconducting phases to rather small temperatures. Instead, a strongly coupled diquark liquid prevails in the thermodynamics under the conditions relevant to neutron-star mergers. At lower densities, the diquarks take over from the single-quark contributions, suggesting a pathway toward hadronization. Our results are consistent with observational constraints on the equation of state of neutron stars, corroborating the presence of strongly coupled quark matter in the interior of these objects.

Many modified-gravity frameworks employ non-Riemannian connection degrees of freedom, including torsion and nonmetricity. In Einstein-Cartan-type theories, torsion is associated with spin density, while more general metric-affine frameworks can be investigated through phenomenological searches for in-matter torsion and nonmetricity backgrounds. This work applies an effective field theory approach to characterize general couplings of electron and neutron operators to spacetime torsion and nonmetricity up to mass dimension six, predicting novel neutron-polarization signatures in the presence of an electron background. Neutron spin-rotation data from a polarized-electron ensemble inside a compensated ferrimagnet are used to constrain for the first time axially symmetric, direction-dependent in-matter torsion and nonmetricity combinations.

Bayesian analyses of heavy-ion collisions rely on functional inputs, such as temperature-dependent transport coefficients and the equation of state, whose prior specification remains a significant source of uncertainty. Standard approaches employ low-dimensional parametrizations that can impose artificial correlations and leave the resulting inference sensitive to the assumed functional form. We develop a nonparametric framework for constructing priors over such functions using Gaussian processes, tailored to emulator-based inference in heavy-ion phenomenology. Truncated Karhunen–Loève expansions yield optimized finite-dimensional representations suitable for use as emulator inputs. We investigate how physical constraints can be incorporated into these priors, demonstrating that rejection-based methods produce non-Gaussian measures and induce nontrivial correlations in the expansion coefficients. By contrast, pushforward constructions enforce the constraints while preserving a tractable Gaussian measure in a latent space. These results provide a systematic framework for incorporating physical constraints into functional priors and clarify their effects on the statistical structure of the finite-dimensional representations used in Bayesian inference.

We analyze 17 years of Fermi-LAT data to study the diffuse $\gamma$-ray emission along the Galactic plane and its connection to cosmic-ray (CR) propagation. Accounting for correlated instrumental systematics, we find decisive evidence for a spectral break at $\sim20-30$ GeV, present across the inner Galactic disk, with a preference of $\Delta\chi^2=39.78$ ($4.44 \sigma$ global). The energy and amplitude of this feature are in striking agreement with the spectral feature observed in local CR nuclei, indicating that it is a global property of the Galactic disk rather than a local phenomenon. The measured slope change, $\Delta\gamma \simeq 0.20$, is consistent with local CR data and with expectations from a transition in the CR diffusion regime from Kolmogorov to Kraichnan turbulence. Our results provide strong evidence that diffuse $\gamma$-ray emission along the Galactic disk is dominated by $\pi^0-$decay emission up to a hundred GeV. These findings provide key insights into the origin of the CR spectral hardening and the propagation of CRs throughout the Galaxy, and illustrate how this multimessenger approach can be used to probe the origin of features in the CR spectra, such as the long-studied CR Knee.

Precision tracking of Earth–Moon and Earth–satellite ranges offers a novel, low-frequency avenue for detecting gravitational waves from inspiralling massive black hole binaries, complementary to space-based interferometers. In this paper, we propose a first study of the reconstruction of the binary parameters from a synthetic set of range observations. Set-up: Assuming an ideal unperturbed Keplerian motion for the earth-satellite binary, we develop a framework for reconstructing the chirp mass $\mathcal M_c$ and luminosity distance $D_L$ of chirping sources from the perturbations they induce on ranging observables, using both Lunar Laser Ranging (LLR) and a two-satellite ranging configuration (GUEST) as concrete case studies. Result: We find that chirp-mass recovery tightly converges as a power law in SNR ($\sigma_{M_c}/M_c \propto \mathrm{SNR}^{\alpha}$, $\alpha \simeq -1$ to $-1.8$) for both LLR and GUEST. In contrast, the luminosity distance suffers from a severe, SNR-independent degeneracy with the sky-orientation angles in the LLR configuration, yielding fractional biases and uncertainties of tens to over a hundred percent regardless of signal strength. The two-satellite GUEST configuration breaks this degeneracy and restores a convergent, SNR-dependent recovery of $D_L$ comparable in scaling to that of the chirp mass. These results demonstrate that multi-baseline ranging architectures are essential for extracting luminosity-distance information from ranging-based gravitational wave searches, while chirp-mass measurements remain reliably accessible even with a single ranging baseline such as the Earth–Moon system.

The Advanced X-ray Imaging Satellite (AXIS) was a mission concept designed to improve upon the sensitivity and spatial resolution of the Chandra X-ray Observatory and XMM-Newton. Although AXIS was not selected for implementation, the concept study defined a mature instrument design with low-background, arcsecond imaging over the $0.3$-$10$ keV energy range, a large effective area, and a wide field of view. These capabilities provide a useful benchmark for the dark matter decay sensitivity of future X-ray observatories. We estimate the reach of a future AXIS-like instrument for narrow photon lines from decaying keV-scale dark matter, including axion-like particles and sterile neutrinos. For Galactic center observations, we find projected lifetime sensitivities of order $10^{31}$ s, improving upon existing limits by up to an order of magnitude over part of the keV mass range.

We study the nonequilibrium response of a one-dimensional Bose-Hubbard medium to a two-magnon bound state propagating along an attractive XXZ chain. A Holstein-type displacement coupling makes the magnon density act both as a local chemical-potential perturbation and as a source of bosons. We derive a long-wavelength hydrodynamic description of the density and phase fluctuations and test it against matrix-product-state simulations of the full coupled dynamics. The theory predicts a comoving near-field deformation together with retarded density waves confined to a sound cone. In the Mott regime, the deformation remains localized around the moving pair. In the compressible regime, two counterpropagating fronts detach and approach the semiclassical sound velocity, recovered from the equilibrium density with no fitted parameters. The coupling also induces a dynamical backreaction that slows the bound state and broadens its magnon-density profile. The comparison delimits where hydrodynamics stays quantitative once the probe reacts back on the medium.

Pomeron loops are known to arise naturally as building blocks of high energy scattering amplitudes as soon as one starts to consider corrections to single Pomeron exchange, i.e. to high energy resummation based on the Balitsky-Fadin-Kuraev-Lipatov evolution equation. While some authors argue that Pomeron loops provide only very small corrections, a 2013 study found that the complete QCD Pomeron loop provides a large correction, which can exceed the single Pomeron contribution already at LHC energies. In this paper we carefully review the derivation of the single Pomeron loop and evaluate the resulting expression numerically, making use of a representation of the triple Pomeron vertex by Korchemsky. While we do not confirm the findings of the 2013 study, we find that the Pomeron loop can provide a 24%-39% correction at lowest currently accessible values of $x$ and hard scales at the non-perturbative boundary.

We utilize renormalization group equations (RGEs) for neutrino oscillations in matter to decipher the structure of exact matter invariants. By combining the RGEs with the $S^{}_3$ permutation covariance under relabeling of the neutrino mass eigenstates, we recast all five algebraically independent matter invariants in the three-flavor framework as exact first integrals. Treating the matter potential as a matter spurion and imposing the cancellation conditions for the $1/\widetilde\Delta_{ij}^{}$ poles in the RGEs, we further prove that the three-flavor framework contains only two independent monomial invariants, which can be related to the Naumov and Toshev relations. We then extend the analysis to the four-flavor framework, where we uncover a complete set of eleven algebraically independent matter invariants and prove that the rank-two electron–sterile spurion obstructs the common pole cancellation required for any nontrivial multiplicative monomial invariant.

This paper presents the impact of the inclusion of next-to-leading-order (NLO) QCD and electroweak (EW) corrections for dimension-6 Standard Model Effective Field Theory (SMEFT) predictions for the Higgs decays in Higgs couplings measurements at the Large Hadron Collider. Such higher-order corrections will be increasingly important for the precise Higgs and electroweak measurements expected at the High-Luminosity Large Hadron Collider (HL-LHC). The results are compared with a SMEFT parameterisation employing inputs from a previous ATLAS study, in which the dimension-6 SMEFT contributions are evaluated for each production and decay process at the lowest non-vanishing perturbative QCD order of the corresponding SM process. The effects of the SMEFT NLO QCD/EW contributions to the Higgs decay channels are largest for 2-fermion operators involving the third generation. The sensitivity to the Higgs tri-linear coupling is also explored.

The measured hadron yields in heavy-ion collisions are well described by thermal particle production at temperatures close to the QCD pseudo-critical transition. However, if particles are produced in thermal equilibrium, then the in-medium effects, e.g., broadening of their spectral functions, must be taken into account. In this work, we study for the first time the effect of the thermal broadening of the light vector-meson spectral functions on light hadron production in heavy-ion collisions. We generalize the efficient resonance decay framework FastReso to resonances with finite-width spectral functions. We then compute the pion, kaon and proton spectra from the decays of hadron resonances for in-medium and vacuum spectral functions. We perform a simultaneous blast-wave fit with decay feed-down to measured particle spectra in central Pb-Pb and Xe-Xe collisions at the LHC. We find an increase in pion spectra at low momenta, from including thermally broadened $\rho$ and $\omega$ mesons. Additional pion yield from finite-resonance widths reduces the commonly observed discrepancy between models and data, but does not completely resolve the soft pion puzzle in heavy-ion collisions.

We prove explicitly the n-point K-identities we proposed previously in the calculation of one tensor hard string scattering amplitudes (HSSA). These K-identities were the key to obtain the stringy scaling behavior in the saddle point calculation of the n-point HSSA and, on the other hand, to consistently match with the calculation of decoupling of zero norm states. Moreover, we introduce a G function to generate an infinite set of generalized K-identities (GKI). The lowest order set of these GKI is the scattering equations (SE) used in the calculation of field theory amplitudes in the CHY formalism. The next to leading order set of these GKI is the K-identities used previously in the calculation of one tensor HSSA. We expect that the higher order sets of these GKI can find applications in calculating other HSSA.

We investigate the discovery potential of a singly produced vector-like top quark $T$ in the $T\to tZ$ decay channel at future muon-proton ($\mu p$) colliders, considering three benchmark center-of-mass energies: $\sqrt{s}=5.29$, $6.48$, and $9.16$~TeV. The baseline signal final state consists of a semileptonic top decay $t\to bW\to b\ell\nu$ and a hadronic $Z\to q\bar{q}$ decay, where the collimated quark pair from the $Z$ boson is reconstructed as a single large-radius fat jet $J$. Full detector-level Monte Carlo simulations are performed for both the signal process and the dominant Standard Model backgrounds. We derive the $5\sigma$ discovery contours and the $95\%$ confidence level exclusion limits in the two-dimensional parameter space spanned by the VLQ mass $m_T$ and the effective coupling $g^*$. A comparison with the $T\to Wb$ channel and with searches at other collider facilities reveals that the $T\to tZ$ decay mode provides complementary sensitivity and offers unique advantages for probing high-mass vector-like $T$ quarks in the boosted jet topology.

We systematically explore the $S$-wave tetraquark systems $Qs\bar{n}\bar{n}$, $QQ\bar{n}\bar{n}$, $QQ\bar{Q}\bar{Q}$, and $ss\bar{s}\bar{s}$ ($Q=c,b$; $n=u,d$) within the constituent quark potential model. We incorporate all K-type Jacobi coordinates in addition to the conventional H-type configurations, optimize the basis expansion via a stochastic parameter generation strategy, and apply the complex scaling method to identify bound and resonant states. Our calculations demonstrate that while conventional H-type configurations suffice for low-lying states such as the $T_{cc}(3875)^+$ molecular candidate, the inclusion of K-type configurations becomes important for extracting highly excited resonances, allowing higher-energy resonances absent in H-only calculations to be identified. Furthermore, we identify resonance candidates for the $T_{cs0}(2900)$, $X(6900)$, and $X(7200)$, whereas the absence of fully-strange compact poles below 2.6 GeV challenges the interpretation of $\phi(2170)$ and $X(2370)$ as $S$-wave compact $s s \bar{s} \bar{s}$ tetraquarks.