Thu·Apr 30, 2026Thursday·April 30, 2026

1. 01*

   When JIMWLK evolution really matters: the example of incoherent diffraction

   T. Lappi🇫🇮 · D.N. Triantafyllopoulos🇮🇹

   We consider high energy scattering in the effective theory of the Color Glass Condensate. The most convenient degrees of freedom are Wilson lines encoding multiple gluon exchanges, whose evolution with energy follows the JIMWLK equation. Instead of using the latter, very often one resorts to a Gaussian Approximation (GA), which is known to be remarkably accurate in describing a wide class of multi-gluon correlators whose expansion in the weak scattering limit starts with an exchange of only two gluons. Here we demonstrate, both analytically and numerically, that such an approximation is not valid for correlators which start with an exchange of four gluons. As a main example, we focus on incoherent diffraction in photon-nucleus collisions and we show that the discrepancy between the JIMWLK and the GA results is driven by weak scattering and further persists in the regime where unitarity corrections begin to become important. The JIMWLK calculation leads to cross sections which are systematically larger in all kinematic regimes of interest.

   hep-phPRD(2026)·2 citations
2. 02*

   Recent Developments in IR-Improved Amplitude-Based Resummation in Precision High Energy Collider Physics

   B.F.L. Ward (1)🇺🇸 · S. Jadach (2)(a)🇵🇱 · W. Placzek (3)🇵🇱 · M. Skrzypek (2) · Z. Was (3)🇵🇱 · S. Yost (4) · A. Siodmok (3) ((1) Baylor University, Waco, TX, USA, (2) Institute of Nuclear Physics, Krakow, PL, (3) Jagiellonian University, Krakow, PL, (4) The Citadel, Charleston, SC, USA, (a) deceased)🇵🇱

   We present recent developments in precision high energy collider physics based on the IR-improvement of unintegrable singularities in the infrared regime via amplitude-based resummation in $QED\times QCD\subset SU(2{)}_L\times U_1\times SU(3{)}^c$. We focus on specific applications relevant to precision observables in LHC/FCC, LC, CLIC, CEPC, and CPPC physics, for which we present new results and some new issues.

   hep-ph0 citations
3. 03*

   Radiative charmonium decays in a contact-interaction model with dynamical quark anomalous magnetic moment

   Yehan Xu🇨🇳 · Zanbin Xing🇨🇳 · Khépani Raya🇪🇸 · Lei Chang🇨🇳

   The BESIII Collaboration has recently reported two measurements of the two-photon decay width of the ${\eta }_c$ meson. The 2024 result is significantly larger than most theoretical and empirical expectations, while a subsequent measurement published in early 2026 shows better agreement with the world average and conventional theoretical estimates. In this work, we study the ${\eta }_c\to \gamma \gamma$ and $J/\psi \to \gamma {\eta }_c$ processes within a contact interaction model that incorporates valence-quark anomalous magnetic moment effects, which are absent in standard treatments. Besides achieving agreement with modern lattice QCD estimates for these observables, we find that the 2024 central value for ${\eta }_c\to \gamma \gamma$ lies above the range that could be accommodated by the present framework, whereas the 2026 result is naturally consistent with it.

   hep-phPRD(2026)·1 citation
4. 04*

   Gravitational Properties of the Monopole Bag

   Yu Komiya🇯🇵 · Fumihiro Takayama🇯🇵

   Axionic cosmologies constitute a class of models with phenomenologically rich symmetry breaking in the early universe. In the case where monopoles are present in such a background, the axion profile may be deformed; it is possible to construct a ``monopole bag" state composed of a central monopole within a closed axion domain wall. We consider the gravitational properties of this hybrid defect, and find a both horizon-less and a black hole-like final state can result as remnants of the monopole-domain wall system after gravitational collapse for different input parameters. We demonstrate that the latter classifies as dyonic regular black hole, evading the usual singular gravitational collapse and retaining a non-trivial axionic profile through exotic electromagnetic properties of an axionic Chern-Simons term.

   hep-phastro-ph.COgr-qchep-th0 citations
5. 05*

   Exponentially improved quantum simulation of scalar QFT

   Qing-Hong Cao🇨🇳 · Ying-Ying Li🇨🇳 · Xiaohui Liu🇨🇳 · Liang-Qi Zhang🇨🇳 · Ke Zhao🇨🇳

   Quantum simulations of scalar quantum field theories (QFT) provide important benchmarks for demonstrating quantum advantage. We revisit digitization in the occupation basis, which is typically hindered by unfavorable circuit depth scaling. We present an approach that achieves exponential reductions in circuit depth and significantly mitigates Trotter errors by diagonalizing field operators prior to their decomposition into Pauli strings. Focusing on a scalar QFT in 2+1 dimensions, we show that this method substantially reduces circuit depth and CNOT gate counts for time evolution. Using the Lorentzian energy-energy correlator as a benchmark observable, we find parameter regimes in which occupation-basis digitization converges more rapidly with respect to local truncation than the amplitude-basis approach of Jordan, Lee, and Preskill. These results provide both algorithmic advances and phenomenological benchmarks for studies of light-ray observables on near-term quantum devices.

   hep-phhep-latquant-ph2 citations
6. 06*

   Light sea-quark flavor asymmetry and angular momentum of the nucleon in a scalar-vector spectator model

   Parashmani Thakuria🇮🇳 · Madhurjya Lalung🇮🇳 · Jayanta Kumar Sarma🇮🇳

   We present a light-front spectator model that describes the proton as an active sea antiquark paired with a composite scalar-vector spectator. Using a spatial profile based on soft-wall AdS/QCD, we fit our initial parameters to CT18NNLO data and Bacchetta-Radici extractions at an initial scale of ${\mu }_0^2=1.0{\text{GeV}}^2$. By allowing these parameters to evolve dynamically, we extend our distributions up to ${\mu }^2=100{\text{GeV}}^2$. We specifically calculate the sea-quark asymmetry at the SeaQuest scale, predicting a sustained $\bar{d}$ enhancement at high $x$ that is in excellent agreement with recent E906 measurements. Additionally, we calculate the leading chiral-even generalized parton distributions (GPDs) and evaluate the total angular momentum carried by the sea quarks, comparing our findings with established results.

   hep-ph0 citations
7. 07*

   Semileptonic $B_q$ decays to heavy tensor mesons

   Pietro Colangelo🇮🇹 · Fulvia De Fazio🇮🇹 · Carlo la Torre🇮🇹 · Giuseppe Roselli🇮🇹

   The semileptonic decays of $B_q$ mesons ($q=u,d,s$) to $J^P=2^{+}$ charmed mesons are investigated. The form factors parametrising the hadronic matrix elements of the weak vector and axial-vector quark currents are evaluated using light-cone QCD sum rules with external $B_q$ state, including the 3-particle contributions. The form factors of pseudoscalar and tensor quark currents occurring in extensions of the Standard Model are also determined. The relations expected in the heavy quark limit are tested, providing a hint about the size of finite heavy quark mass corrections for the various form factors. Results are presented for the semileptonic $B_q$ to heavy tensor meson decay rates in the Standard Model, and for the ratios testing Lepton Flavour Universality.

   hep-phhep-exhep-latJHEP(2026)·1 citation
8. 08*

   Particle seismology: mechanical and gravitational properties from parton-hadron duality

   Enrique Ruiz Arriola🇪🇸 · Wojciech Broniowski🇵🇱

   The internal structure of hadrons is characterized by form factors which correspond to matrix elements of currents. Among those, the stress-energy-momentum tensor is a universally conserved quantity providing the gravitational form factors, from which mechanical properties may be derived via the response to the space-time fluctuations. They have received much attention because of their role as moments of the Generalized Parton Distributions, where the stress-energy-momentum tensor couples to two photons, and more recently, due to the explicit lattice QCD determination for the pion and nucleon. In these lectures we attempt a pedagogical review of the topic from a purely hadronic point of view, based on the notion of dispersion relations, meson dominance, and parton-hadron duality. We show that despite the overwhelming simplicity of the approach, a rather successful description of the lattice QCD data is achieved.

   hep-phhep-latnucl-th1 citation
9. 09*

   Hybrid hadrons at rest and on the light front

   Edward Shuryak🇺🇸 · Ismail Zahed🇺🇸

   We present a unified description of heavy hybrid hadrons based on a constituent-gluon picture embedded in the Born-Oppenheimer (BO) framework. In this approach, the gluonic excitation is treated as a dynamical quasiparticle with a mass generated by instanton-induced interactions. We propose a simple variational derivation of the BO potentials. The main focus of the paper is the derivation of light-front wave functions for hybrid systems, specifically for the $ccg$ and $qqqg$ cases. We employ both variational methods and numerical solutions of the Schrödinger equation in momentum representation. Using the resulting wave functions, we compute the gluon PDFs for these systems.

   hep-ph0 citations
10. 10*

    Probing Sub-GeV Dark Matter via Migdal Effect-Induced Electron Excitations

    Felix Kahlhoefer🇩🇪 · Liangliang Su🇩🇪

    The electron ionization predicted by the Migdal effect in dark matter-nucleus scattering enhances experimental sensitivity to sub-GeV dark matter. In this work, we demonstrate that lower-energy electron excitations provide a novel and promising pathway, enabling the detection of even lighter dark matter particles previously considered inaccessible for direct searches. Direct detection experiments employing a superfluid ${}^4$He target can exploit this channel by observing electronic excitations via UV-photon emission. We calculate the resulting event rates and find that electron excitations induced by the Migdal effect make it possible to probe dark matter-nucleus scattering for dark matter masses as small as a few MeV.

    hep-ph1 citation
11. 11*

    Effect of sub-nucleon fluctuations on the DVCS process in proton and nuclear targets at the EIC

    J. Cepila🇨🇿 · V. P. Goncalves🇧🇷 · A. Ridzikova🇨🇿

    The impact of the sub - nucleon fluctuations on the Deeply Virtual Compton Scattering (DVCS) process at the Electron - Ion Collider (EIC) is investigated considering proton and nuclear targets. Assuming the hot - spot model, we estimate the energy dependence of the coherent and incoherent cross - sections for different values of the photon virtuality and atomic number. Predictions for the $t$ - distributions are also presented. We demonstrate that the sub - nucleon fluctuations in the proton, as described by the hot - spot model, implies a turn - over in the energy dependence of the incoherent cross - section, with the position of the maximum being dependent of the photon virtuality. Our results indicate that the ratio between the coherent and incoherent cross - sections increases with energy, atomic numbers and for smaller values of $Q^2$. Moreover, we predict a maximum in the $t$ - distribution of the nuclear incoherent cross - section at a fixed center - of - mass energy, which is dependent on the atomic number and $Q^2$.

    hep-ph0 citations
12. 12*

    GLoop: A Monte Carlo program to construct higher-loop integrals from lower-loop structures

    Roberto Pittau🇪🇸

    We present GLoop, a Fortran90 computational framework that allows one to compute by Monte Carlo a certain class of higher-loop integrals in terms of lower-loop building blocks. This is based on a recently introduced method that enables the numerical computation of integrals defined by i epsilon deformations acting on single pole singularities without the need for an explicit analytic contour deformation. We provide detailed, worked-out examples and routines to show how our strategy works. These can be used as a starting point for the reader to develop her/his own calculations.

    hep-ph0 citations
13. 13*

    Continuum contribution to charged-current absorption of low-energy ${\nu }_e$ on ${}^{40}$Ar

    Steven Gardiner🇺🇸 · Pablo Barham Alzás🇨🇭 · Alexis Nikolakopoulos🇺🇸 · Luca H. Abu El-Haj🇺🇸 · Natalie Jachowicz🇧🇪 · Vishvas Pandey🇺🇸

    Accurate modeling of the absorption of tens-of-MeV ${\nu }_e$ on ${}^{40}$Ar is needed to enable measurements of astrophysical neutrinos using large liquid argon time projection chamber (LArTPC) detectors, such as those planned for the Deep Underground Neutrino Experiment (DUNE). We revisit the MARLEY neutrino interaction model used in present estimates of DUNE sensitivity to supernova and solar neutrino signals. Multiple theoretical refinements are pursued, especially in the unbound continuum region of nuclear excitation energy. Inclusive charged-current neutrino-argon cross sections are calculated using a hybrid strategy. Nuclear transitions to unbound states are treated using a Hartree-Fock Continuum Random Phase Approximation (HF-CRPA) model, including forbidden contributions. Allowed transitions to low-lying discrete levels are also included using indirect measurements and approximate corrections for the momentum transfer dependence. Exclusive predictions are obtained by coupling these calculations with a statistical nuclear de-excitation model. The impact on observables of interest for DUNE and similar experiments is examined in terms of both total and differential cross sections. Our refined calculations predict a lower allowed portion of the cross section relative to the prior MARLEY model. At neutrino energies appreciably below 100 MeV, the inclusion of forbidden transitions does not fully compensate for the loss of allowed strength. For a representative neutrino burst from a galactic core-collapse supernova, our results suggest that MARLEY 1.2.0 overestimates the event yield in a DUNE-like detector by approximately 20%. However, because this overestimation is more severe at backwards angles, use of the charged-current ${\nu }_e$-${}^{40}$Ar reaction for supernova pointing may be more feasible than previously expected.

    hep-phnucl-th3 citations
14. 14*

    When Two Loops Matter: Electroweak Precision in the SMEFT

    Lukas Born🇨🇭 · Admir Greljo🇨🇭 · Anders Eller Thomsen🇨🇭

    We identify a novel next-to-leading order renormalization effect in the dimension-six SMEFT with direct phenomenological impact. The Higgs-Yukawa operator that modifies the top-Higgs coupling ${\kappa }_t$ induces a shift in the $W$ mass at two-loop order through a large anomalous dimension, rendering electroweak precision observables a powerful indirect probe of ${\kappa }_t$. We show that this effect is essential for the consistent interpretation of data from future Tera-$Z$ and Giga-$W$ factories such as FCC-ee. The effect is realized in a simple renormalizable two-Higgs doublet model.

    hep-phhep-ex3 citations
15. 15*

    Null Tests and Lepton Universality in ${\Xi }_{cc}$ Baryon Decays

    Hindi Zouhair🇲🇦

    We develop a precision framework for doubly charmed baryon decays based on symmetry-protected observables and effective-field-theory diagnostics. In nonleptonic ${\Xi }_{cc}$ decays, we construct a null combination of widths that vanishes in the heavy-diquark factorization limit, providing a direct probe of nonfactorizable QCD dynamics. For semileptonic decays, we identify the light-lepton universality ratio $R_{{\Xi }_c}^{\mu e}$ as an observable in which leading hadronic normalization cancels at the amplitude level, yielding direct sensitivity to short-distance charged-current interactions. Percent-level precision probes $|C_{V_L}^{\mu }|\sim \mathcal{O}(10^{-2})$, whereas $\mathcal{O}(10^{-1})$ deformations induce order-one deviations. Scalar contributions remain parametrically suppressed. Combining baryonic and mesonic inputs, we show that ${\Xi }_{cc}$ decays constrain the same short-distance interaction with complementary scaling, lifting degeneracies inherent to meson-only analyses. Mapping to a charged-vector benchmark demonstrates sensitivity to multi-TeVnew-physics scales. These results establish doubly charmed baryons as an independent probe of charged-current interactions beyond the Standard Model.

    hep-ph0 citations
16. 16*

    Nanohertz gravitational waves from the baryon-dark matter coincidence

    Alessia Musumeci🇩🇪 · Jacopo Nava🇮🇹 · Silvia Pascoli🇮🇹 · Filippo Sala🇮🇹

    The nanohertz gravitational waves (GW) observed by pulsar timing arrays may originate from a cosmological first-order phase transition (PT) at $\sim$ 100 MeV. Taking this possibility seriously motivates the question: why 100 MeV? We point out that a PT at exactly those scales is predicted by the generation of the baryon asymmetry from a dark asymmetry via resonant neutron-dark matter oscillations, and we prove that this PT can induce an observable GW signal compatibly with all experimental constraints. This proposal predicts dark matter self-interactions close to their observational upper limits and lowers the maximal expected mass of neutron stars. Independently of GW, this baryogenesis mechanism is tested by searches for missing-energy at the LHC and for neutron decays. We keep the model consistent with big-bang nucleosynthesis by adding heavy neutral leptons below 100 MeV, which generate neutrino masses and can induce further experimental tests.

    hep-ph2 citations
17. 17*

    $\mathcal{H}$olographic $\mathcal{N}$aturalness and Information See-Saw Mechanism for Neutrinos

    Andrea Addazi🇨🇳 · Giuseppe Meluccio🇮🇹

    The microscopic origin of the de Sitter entropy remains a central puzzle in quantum gravity related to the cosmological constant problem. Within $\mathcal{H}$olographic $\mathcal{N}$aturalness, we propose this entropy is carried by light, coherent degrees of freedom - "hairons" - emerging as moduli of gravitational instantons on orbifolds. From the Euclidean de Sitter instanton ($S^4$), we construct a new class of orbifold gravitational instantons, $S^4/{\mathbb{Z}}_N$, where $N$ corresponds to the de Sitter entropy. The moduli space dimension scales linearly with $N$, and we identify these moduli with hairon fields. A ${\mathbb{Z}}_N$ symmetry from Wilson loops ensures mode distinguishability, yielding the correct entropy. Hairons acquire a mass of the order of the Hubble scale with negligible interactions, suggesting the de Sitter vacuum is a Bose-Einstein condensate of these excitations. We then unify the neutrino mass generation with the cosmological constant via gravitational topology. The small neutrino mass emerges naturally without new physics beyond the Standard Model. The gravitational Chern-Simons structure and anomaly force a topological Higgs mechanism, leading to neutrino condensation via $S^4/{\mathbb{Z}}_N$ instantons. The topological degrees $N\sim M_{\text{P}}^2/\Lambda \sim 10^{120}$ provide both a holographic entropy counting and a $1/N$ information see-saw mechanism for neutrino masses. Predictions: (i) neutrino superfluid condensation forming Cooper pairs below meV as cold dark matter; (ii) resolution of the strong CP problem via a QCD composite axion; (iii) time-varying neutrino masses tracking th dark energy evolution; (iv) signatures in astroparticle physics, ultra-high-energy cosmic rays and high magnetic field experiments.

    hep-phhep-thParticles(2026)·2 citations
18. 18*

    Leptoquarks and the Emergence of the Standard Model Gauge Group in a Self-Consistent Preon Model

    Risto Raitio🇫🇮

    We show that in a self-consistent preon model, where Standard Model quarks and leptons are three-body composites confined at a metacolor scale Lambda_cr ~ 10^14 GeV, both leptoquarks and the Standard Model gauge group SU(3)_c x SU(2)_L x U(1)_Y emerge as structural predictions rather than inputs. Combining the preon content of a quark with that of a lepton gives exactly four distinct six-body bosonic leptoquark composites per generation, with electric charges Q = +2/3, -1/3, -1/3, -4/3 and a universal B-L = -2/3 fixed by the preon charge assignments. Their mass is of order Lambda_cr rather than of order the SM fermion masses, because the dynamical near-cancellation that produces light fermion masses is specific to three-body fermionic composites and does not extend to six-body bosonic ones. The fractional B-L = -2/3 forbids proton decay via single leptoquark exchange, requiring a dimension-12 operator and giving tau(p -> e+ pi0) ~ 10^58 years, consistent with the experimental bound > 2.4 x 10^34 years. It is shown that the SM gauge group emerges as a low-energy symmetry consistent with the Planck-scale boundary condition, and leptoquarks are required -- not merely permitted -- by the matching. The anomaly-matching argument extends to a tower of 3n-body composites, each level imposing consistency conditions on the next; we call this the vertical bootstrap and advance it as the organizing principle of the preon program.

    hep-ph2 citations
19. 19*

    Chiral-Transport-Induced Collective Modes in Strong Magnetic Fields and Their Implications for Neutron Star Phenomenology

    Sota Hanai🇯🇵

    In this thesis, we study the collective modes induced by the chirality of elementary particles in magnetized media and their implications for neutron star phenomenology. We theoretically predict that the chiral magnetic wave can arise in quark matter inside neutron stars, resulting in the emergence of novel types of seismic oscillations and associated gravitational waves in the context of asteroseismology. We also investigate the response to dynamical electromagnetic fields and find that a dynamical screening, distinct from the conventional Landau damping, occurs due to the chiral anomaly.

    hep-phastro-ph.HEnucl-th0 citations
20. 20*

    Quantum Complexity and New Directions in Nuclear Physics and High-Energy Physics Phenomenology

    Caroline E. P. Robin🇩🇪 · Martin J. Savage🇺🇸

    Advances in quantum information science (QIS) are providing transformative insights into the complexity of quantum many-body systems, potentially defining new frontiers in nuclear and high-energy physics. This review explores how QIS-derived techniques are fostering new analytic frameworks and algorithms - both classical and quantum - to tackle (some of the) present barriers to discovery in fundamental physics, with applicability to other science domains. We highlight how these techniques are shedding new light on the structure and dynamics of hadrons, nuclei, matter in extreme conditions, and beyond. Importantly, they are expected to play an essential role in the development of large-scale quantum simulations of such systems, particularly in setting the balance among quantum and classical computational resources.

    ↳ quant-phhep-lathep-phnucl-th17 citations
21. 21*

    Tidal Heating of Stellar Clusters in Fuzzy Dark Matter Halos

    Yiheng Liu · Xinyu Li

    Ultra-faint dwarf galaxies serve as powerful testing grounds for wave dark matter models through dynamical stellar heating. Previous simulation-based work derived a lower bound on the fuzzy dark matter particle mass using a diffusion approximation valid only when the de Broglie wavelength is much smaller than the galaxy's half-light radius. We simulate the dynamical evolution of stellar clusters in FDM halos across a wide mass range and find that for sufficiently low masses, where the de Broglie wavelength is much larger than the cluster size, tidal heating is the main mechanism. We also find that a reduced soliton mass and tidally stripped halo can suppress the heating. We demonstrate that in order to constrain FDM mass from cluster heating, the structure and environment of the FDM halo must be carefully considered.

    ↳ astro-ph.COastro-ph.GAgr-qchep-ph3 citations
22. 22*

    Precision Spectroscopy of 2S-nS Transitions in Atomic Hydrogen: A Determination of the Proton Charge Radius

    R. G. Bullis · W. L. Tavis · M. R. Weiss · J. Orellana Cisneros · A. J. Cheeseman · U. D. Jentschura🇺🇸 · D. C. Yost

    We present absolute frequency measurements of 2S_{1/2}-nS_{1/2} two-photon transitions with n = 8, 9, and 10 in a cryogenic beam of atomic hydrogen. Each transition has been measured with a fractional uncertainty of approximately 2.6*10^(-12). Combining the results from this work and the 1S_{1/2}-2S_{1/2} transition frequency, we extract a root-mean-square proton radius of r_p = 0.8433(31) fm and a Rydberg frequency of cR_{\infty} = 3,289,841,960,252.9(9.7) kHz. These are in good agreement with the CODATA 2022 recommended values.

    ↳ physics.atom-phhep-phPRL(2026)·3 citations
23. 23*

    The End of the First Act: Spectral Running, Interacting Dark Radiation, and the Hubble Tension in Light of ACT DR6 Data

    Mathias Garny🇩🇪 · Florian Niedermann🇸🇪 · Martin S. Sloth🇩🇰

    We point out that constraints on $\Delta N_{\mathrm{eff}}$ reported by the ACT collaboration in their DR6 data release are surprisingly sensitive to the assumptions made about the initial power spectrum from inflation. The ACT collaboration reports no evidence of new light degrees of freedom alongside a low value of the expansion rate, thus confirming the Hubble tension. However, as we show here, when considering self-interacting dark radiation and including running, ${\alpha }_s$, and running of the running, ${\beta }_s$, of the spectral index $n_s$, the picture changes significantly. Confronting this extended model with Planck, ACT DR6, DESI DR2, and uncalibrated Pantheon+ data, we find the significantly relaxed bound $\Delta N_{\text{eff}}<0.58$ at 95$\%$ CL, together with a $2.9\sigma$ ($2.6\sigma$) preference for ${\alpha }_s>0$ (${\beta }_s>0$), while the Hubble tension is reduced to $2.2\sigma$ with only three more parameters compared to $\Lambda$CDM. If the dark radiation fluid is initially coupled to dark matter, and undergoes dark radiation-matter decoupling (DRMD) around matter-radiation equality, predicting dark acoustic oscillations with drag horizon $r_{d,\mathrm{DAO}}\approx 60\mathrm{Mpc}/h$, the bound is further relaxed to $\Delta N_{\text{eff}}<0.68$ at 95$\%$ CL, reducing the Hubble tension below $2\sigma$. We also discuss how ${\alpha }_s$ and ${\beta }_s$ could naturally appear in inflationary scenarios, possibly connected to the end of a first act of inflation. In this case dark radiation is mostly probed by scales covered by Planck and DESI, while smaller scales carry information on inflationary dynamics.

    ↳ astro-ph.COhep-phhep-th6 citations
24. 24*

    Thermodynamics of magnetized matter in hot and dense QCD

    Bastian B. Brandt🇩🇪 · Gergely Endrodi🇭🇺

    This chapter, to appear in the section on QCD under extreme conditions within the Encyclopedia of Nuclear Physics, aims to provide a pedagogical introduction to the physics of quarks and gluons in the presence of high temperature, nonzero (isospin) density and strong background electromagnetic fields. Extreme conditions of these types are relevant for the description of high-energy heavy-ion collisions, neutron stars and their mergers, as well as the evolution of the early Universe in its first microsecond. Most of the existing results on this topic have been obtained by means of first-principles simulations of the discretized theory of the strong interactions, lattice Quantum Chromodynamics (QCD). This lays the focus of this review chapter, although various calculations within effective theories of QCD -- most notably chiral perturbation theory -- are also discussed. Furthermore, we provide an outlook concerning open questions and yet uncharted parameter regions within this fascinating system.

    ↳ hep-lathep-phnucl-th3 citations
25. 25*

    Thermal and geometric normal modes of spectral fluctuations in heavy-ion collisions

    Rupam Samanta🇵🇱

    The transverse momentum spectrum of charged particles in ultra-relativistic heavy-ion collisions fluctuates event-by-event, encoding signatures of underlying collective dynamics. Such fluctuations originate from a combined effect of thermal and geometric fluctuations in the initial state. We present a direct decomposition of these spectral fluctuations through principal component analysis performed on the joint covariance structure of normalized spectrum, mean transverse momentum and elliptic flow squared. The first two leading modes explain 99.5\% of the total variance, and are orthogonally rotated by imposing physical constraints motivated by the initial state thermal and geometric response. The resulting thermal and geometric modes bear direct analogy with the vibrational normal modes of a linear triatomic molecule. The thermal mode entirely drives the experimentally measured $v_0(p_T)$, while the geometric mode contributes substantially to $v_{02}(p_T)$ in non-central collisions, providing a transparent explanation of its characteristic low-$p_T$ sign change. The study establishes the first physically motivated interpretation of principal component modes in the field of heavy-ion collisions and provides an experimental window into the thermo-geometric structure of the QGP initial state.

    ↳ nucl-thhep-phnucl-exPLB(2026)·1 citation
26. 26*

    A positive definite formulation of vacuum decay with reduced symmetry

    José R. Espinosa🇪🇸 · Ryusuke Jinno🇯🇵 · Thomas Konstandin🇩🇪 · Shogo Matake🇯🇵 · Taiga Miyachi🇯🇵

    The Euclidean bounce for vacuum decay enjoys an $O(4)$ symmetry that is lost in the presence of impurities than can catalyze the decay. We present a formulation for the calculation of the tunneling decay action, that is explicitly positive definite, for impurities whose effects are spherically symmetric so that the bounce symmetry is reduced to $O(3)$. The action constructed can be regarded as a generalization of the tunneling potential method, which implicitly assumed $O(4)$ symmetry. We show that the action obtained reduces to the tunneling potential for $O(4)$-symmetric cases and provide analytic examples with $O(3)$ symmetry and arbitrary wall thickness.

    ↳ hep-thastro-ph.COgr-qchep-ph0 citations
27. 27*

    Topological and self-dual vortices in a double sigma model with Maxwell coupling

    Francisco C. E. Lima🇧🇷 · Fernando M. Belchior🇧🇷 · Allan R. P. Moreira🇧🇷

    In this work, we construct a double O(3)-sigma model minimally coupled to a Maxwell field in (2+1)-dimensional spacetime and investigate the existence of self-dual magnetic vortex solutions. An analysis of the Bogomol'nyi-Prasad-Sommerfield (BPS) property reveals that both sigma fields belong to the same topological sector and that the potential assumes a periodic cosine-like form. Furthermore, the theory supports the emergence of magnetic vortices with quantized flux, described by two nonlinear O(3)-sigma sectors that effectively combine into a single topological sector in the BPS regime. In addition, we analytically verify the consistency of the BPS structure and its asymptotic behavior. Within this framework, numerical vortex solutions confirm that the field profiles are smooth and spatially localized, with both the magnetic field and the energy density remaining regular and localized.

    ↳ hep-thhep-ph0 citations
28. 28*

    Optimal Architecture and Fundamental Bounds in Neural Network Field Theory

    Zhengkang Zhang🇺🇸

    Neural network field theory (NNFT) represents fields as neural networks and samples field configurations by drawing network parameters from a probability distribution. We identify a previously unexplored architectural freedom in NNFT, parameterized by $\alpha$, that leaves the infinite-width theory invariant but dramatically affects finite-width errors in the calculation of correlation functions. For a massive scalar field, we show that $\alpha =0$, corresponding to propagator-weighted neuron momenta and constant neuron amplitudes, is optimal: it minimizes finite-width variance and uniquely removes IR-sensitive corrections in the interacting theory. Even at $\alpha =0$, relative errors from both bias and variance grow exponentially with distance beyond the correlation length. The bias can be removed by extrapolating to infinite width, which we demonstrate numerically, while the variance imposes a fundamental bound on the achievable signal-to-noise ratio as in lattice field theory. These results chart a path toward developing NNFT into a practical tool for the numerical study of field theories.

    ↳ hep-thhep-ph4 citations
29. 29*

    Continuum-Limit HQET LCDAs from Lattice QCD for Tightening B Decay Uncertainties

    Xue-Ying Han🇨🇳 · Hao-Fei Gao🇨🇳 · Jun Hua🇨🇳 · Xiangdong Ji🇺🇸 · Xiangyu Jiang🇨🇳 · Cai-Dian Lü🇨🇳 · Andreas Schäfer🇩🇪 · Jin-Xin Tan🇨🇳 · Ji-Hao Wang🇨🇳 · Wei Wang🇨🇳 · Ji Xu🇨🇳 · Yi-Bo Yang🇨🇳 and 6 other authors

    Heavy meson HQET light-cone distribution amplitudes (LCDAs) are critical for precision predictions of $B$ meson weak decays, but currently are one of dominant theoretical uncertainties that obscure interpretations of $B$ anomalies and CP-violating measurements. Building on the established HQLaMET framework, supplemented by lattice QCD calculations of the OPE moments, we present a precise lattice QCD calculation of HQET LCDAs by employing multi-ensemble simulations for continuum and physical pion mass extrapolation, quantifying comprehensive systematic errors, and validating results through OPE moment cross-validation. Details of the lattice calculations are provided in a companion paper \cite{HeavymesonDA_long_paper}. Our final results for key inverse moments (at $\mu =1$ GeV) are ${\lambda }_B=0.340(20)$ GeV and ${\sigma }_B^{(1)}=1.685(63)$, with the total uncertainty reduced by a factor of three relative to the previous analysis. These results can greatly reduce the uncertainty in the $B\to K^{\ast }$ form factors in the large-recoil region. This work resolves the long-standing bottleneck in first-principles predictions of heavy meson LCDAs, advancing precision flavor physics to new frontiers.

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* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.