Wed·May 6, 2026Wednesday·May 6, 2026

1. 01*

   From Information Geometry to Jet Substructure: A Triality of Cumulant Tensors, Energy Correlators, and Hypergraphs

   Aritra Bal🇩🇪 · Markus Klute🇩🇪 · Benedikt Maier🇬🇧 · Michael Spannowsky🇩🇪

   Pairwise Fisher graphs capture local covariance information, but they cannot distinguish an irreducible multi-observable radiation pattern from a collection of ordinary pairwise correlations. We show that this missing structure is naturally supplied by higher-order Fisher tensors. In a finite basis of binned EECs, ECFs, or EFPs, and in the natural exponential-family coordinates generated by that basis, the same local tensor has three equivalent interpretations: a coefficient in the local Kullback-Leibler expansion, a connected cumulant of the chosen correlator observables, and a signed weight on a hyperedge linking those observables. This gives an exact Fisher-correlator-hypergraph triality in the local exponential-family embedding. The triality provides a direct construction of physics-informed hypergraphs from correlator data. Extending the quadratic Fisher matrix to the first non-trivial higher tensor identifies genuinely connected multi-observable radiation patterns, supplies hyperedge weights for higher-order Laplacians and message passing, and gives a principled criterion for compressing observable bases beyond pairwise information. We develop these constructions and spell out why the exact cumulant interpretation is special to natural exponential-family coordinates. We illustrate the framework in four applications. In a minimal local-KL study, the cubic Fisher tensor reduces the KL truncation error and isolates the dominant triplet structure. In a two-versus-three prong jet substructure benchmark, the hypergraph selector improves compressed-basis classification. In a 33-observable basis-design problem, the Fisher hypergraph retains more third-order local response at twelve observables. A low-capacity learning benchmark then shows how the same Fisher hyperedges can be used as an interpretable inductive bias for message passing on correlator observables.

   hep-phhep-exstat.ML2 citations
2. 02*

   Solution of the boundary problem for the axial-vector field in the hard-wall AdS/QCD model

   Nihan Aliyev🇦🇿 · Shahin Mamedov🇦🇿

   We solve an equation of motion for the axial-vector field under boundary conditions of the bulk-to-boundary propagator in the framework of the hard-wall model of AdS/QCD. The equation is reduced to the form of a homogeneous ordinary differential equation with varying coefficients. We solve conjugate equations and find fundamental solutions. This allows us to establish main relations and necessity conditions. The integral equation has both Volterra and Fredholm terms and was solved by the iteration method. We apply a new scheme to solve the equation, since all linearly independent necessary conditions for the existence of a solution were defined and used to establish a sufficient condition for Fredholm solvability of the problem.

   hep-phmath-phmath.MP0 citations
3. 03*

   Einstein-de Haas effect and induced rotation in QCD matter

   Dushmanta Sahu🇲🇽

   In this study, we report the first identification of the Einstein-de Haas (EdH) effect in the QCD matter. The EdH effect is a fundamental magnetomechanical coupling wherein magnetic-field-induced spin alignment generates a compensating collective rotation to conserve the total angular momentum. Using an equilibrium hadron gas under an external magnetic field, we show that even remnant magnetic fields at the freeze-out produce induced rotations (${\omega }_{\mathrm{EdH}}$) comparable to typical estimates of fluid vorticity in heavy-ion collisions as inferred from final-state hyperon polarization. This rotation emerges from the magnetic field alone, without any initial vorticity as input. The Einstein-de Haas effect thus establishes hot QCD matter as a self-vortical magnetofluid, where collective rotation can be generated purely from spin alignment, and identifies spin-rotation coupling as a potentially important, previously overlooked component of angular momentum dynamics in relativistic nuclear collisions.

   hep-ph2 citations
4. 04*

   Probing anomalous quartic gauge couplings via vector boson scattering at the same-sign muon collider

   Lopamudra Mukherjee🇮🇳 · Abhik Sarkar🇮🇳

   The measurement of quartic gauge couplings (QGCs) provides a crucial test of the non-Abelian gauge structure of the Standard Model and offers sensitivity to new physics effects. In this work, we explore the potential of the proposed multi-TeV same-sign muon collider, $\mu$TRISTAN, to probe anomalous quartic gauge couplings (aQGCs) through vector boson scattering (VBS) processes. Owing to the same-sign initial state, s-channel contributions are absent, rendering VBS as the dominant production mode and thereby significantly enhancing the sensitivity to aQGCs. Using dimension-8 Standard Model Effective Field Theory (SMEFT) operators, we classify the relevant operator sets contributing to charged and neutral QGCs, and confront them with existing bounds from the LHC. A detailed collider analysis is performed across multiple final states: $2V2\nu$, $V\gamma \ell \nu$, $2V\ell \nu$, $2\gamma 2\ell$, and $2V2\ell$ ($V=$ reconstructed $W$ and $Z$ boson), applying optimized selection strategies. We present the projected sensitivities at the $\mu$TRISTAN with center-of-mass energies 2 TeV and 6 TeV, with integrated luminosities of 1 ab${}^{-1}$ and 10 ab${}^{-1}$, and demonstrate significant improvements over current experimental limits from the LHC. Our results establish $\mu$TRISTAN as a powerful probe of electroweak symmetry breaking dynamics and aQGCs in a model-independent framework.

   hep-phhep-ex0 citations
5. 05*

   Elastic Form Factors of Axial-Vector Mesons: A Contact Interaction Exploration

   R. J. Hernández-Pinto🇲🇽 · L. X. Gutiérrez-Guerrero🇲🇽 · M. A. Bedolla🇲🇽 · J. P. Uribe-Ramírez🇲🇽 · A. Bashir🇲🇽

   We employ a symmetry-preserving treatment of the contact interaction within the coupled for- malism of Schwinger-Dyson and Bethe-Salpeter equations to calculate the elastic form factors of axial-vector mesons. In this study, we present the computation of the charge radii, magnetic mo- ments, and quadrupole moments of axial-vector mesons, including those composed of light quarks, heavy quarks or a light and a heavy quark. Our findings indicate that the electric form factor for axial-vector mesons, like that of vector mesons, crosses zero. Furthermore, this crossing occurs at a lower value for axial-vector mesons than for vector mesons. The results for vector-axial mesons follow a similar hierarchy in charge radii as observed for S, PS, and V mesons, with radii decreasing as the mass of the dressed quarks increases. We also include a term associated with the anoma- lous magnetic moment in the quark-photon vertex. This term has a noticeable impact on both the axial-vector magnetic moment and quadrupole moment, leading to significant percentage changes in their values. We compare our results with those obtained from other models whenever available.

   hep-phPRD(2026)·0 citations
6. 06*

   Constraining Tsallis Corrections to Photon Reheating from Electron-Positron Annihilation: A Phenomenological Approach

   Matias P. Gonzalez🇨🇱

   In this work we generalize the entropy transfer from electron-positron annihilation to photons in the early Universe. The generalization is implemented within the Tsallis formalism by using generalized distribution functions derived from Curado-Tsallis constraints. Through this deformation, the entropy density of the electromagnetic sector is modified, while the photon component is kept extensive. Therefore, the nonextensive correction is introduced only in the $e^{-}{e}^{+}$ pairs. This affects the entropic degrees of freedom before electron-positron annihilation and consequently modifies the temperature ratio $T_{\nu }/T_{\gamma }$. The resulting correction is then mapped into an effective value of \(N_{\rm eff}\) within the instantaneous decoupling approximation. Comparing this effective thermodynamic estimate with CMB$+$BAO data, and using BBN only as an illustrative Gaussian comparison, we obtain an order-of-magnitude phenomenological interval for the nonextensive parameter. The result should not be interpreted as a precision neutrino decoupling constraint, since a full treatment would require solving the kinetic evolution of the neutrino sector, including non-instantaneous decoupling, finite-temperature QED effects and possible spectral distortions.

   hep-phastro-ph.COcond-mat.stat-mechEPJC(2026)·1 citation
7. 07*

   Parton Distribution Functions from Large Momentum Expansion of Current-Current Correlators

   Jialu Zhang🇨🇳 · Xiangdong Ji🇺🇸 · Andreas Schäfer🇩🇪 · Rui Zhang🇺🇸 · Christian Zimmermann🇺🇸

   The universality of the large momentum expansion allows computing parton distribution functions (PDFs) starting from any Euclidean correlator with appropriate large momentum Fourier Components. Here we consider current-current correlators which have been used in short-distance expansion to obtain moments of PDFs. The advantage of such correlators is that they have simple renormalization properties and do not have linear power divergences as in quasi-PDF. However, in lattice calculations, four-point functions are needed. Here we present an expansion formula with current-current correlators up to the next-to-leading order, and preliminary numerical calculations with four-point functions.

   hep-phhep-latnucl-th3 citations
8. 08*

   Mirror Quantum Tomography Finds Unexpected Polarization Phenomena in Z Boson Production in pp Collisions at the LHC

   A. Gautam🇺🇸 · J. C. Martens🇺🇸 · J. P. Ralston🇺🇸 · G. Stejskal🇺🇸 · J. D. Tapia Takaki🇺🇸

   The ATLAS, CMS and LHCb collaborations have reported data for the inclusive production of lepton pairs with invariant mass 80-100 GeV in pp collisions. We find the ATLAS data from at $\sqrt{s}$ =8 TeV shows an unexpected vortex-like configuration of Z boson spins circulating around the beam axis. Associated with this structure is a local maximum of the entropy of the Z-boson polarization density matrix extracted using quantum tomography. Data from CMS and LHCb at $\sqrt{s}=13$ TeV are broadly consistent. The origin of the observed phenomena is unknown but generally related to observables that are formally odd under charge conjugation, parity and time-reversal. Quantum tomography using Standard Model lepton couplings to the Z boson determines the spin-1 density matrix of the system model-independently, bypassing any model of the hadronic production process.

   hep-phhep-ex1 citation
9. 09*

   Does $\psi (4660)$ exist?

   Xian-Chen Wang🇨🇳 · Quanxing Ye🇨🇳 · Qian wang🇨🇳

   We investigate $S$-wave coupled-channel effects in $e^{+}{e}^{-}$ annihilation in the energy region $\sqrt{s}\in [4.0,5.5]\mathrm{GeV}$, including the open-charm final states ${\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$, ${\Xi }_c^{+}{\bar{\Xi }}_c^{-}$, ${\Xi }_c^0{\bar{\Xi }}_c^0$, and $\psi (2S){\pi }^{+}{\pi }^{-}$. Motivated by the recent high-precision BESIII measurements of the $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$ cross section, which shows a nearly flat lineshape around $4.66\mathrm{GeV}$ and a non-zero value right at threshold, in striking contrast to earlier Belle observation, we construct an effective coupled-channel framework by using short-ranged contact potentials in the heavy-quark limit.Two charmonium states, i.e. the $\psi (4360)$ and $\psi (4660)$, assigned as the $4S$ and $5S$ excitations, respectively, are explicitly included. The scattering amplitudes are obtained by solving the Lippmann-Schwinger equation.The Belle and BESIII $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$ and $e^{+}{e}^{-}\to \psi (2S){\pi }^{+}{\pi }^{-}$ cross-sections reveal markedly different pole structures for the $\psi (4360)$. It emerges as a dynamically generated state for the Belle data, whereas it appears as a bare state in the BESIII fit. In contrast, the $\psi (4660)$ pole found on the unphysical Riemann sheet above the ${\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$ threshold is associated with a bare pole on the real axis in both fits.

   hep-ph0 citations
10. 10*

    Search for Long-Lived Dark Photons from Dark Radiation at the LHC

    Chuan-Ren Chen🇹🇼 · Van Que Tran🇹🇼

    We investigate a novel production mechanism for long-lived dark photons at the LHC, arising from dark radiation emitted from $\chi$ in $Z\to \bar{\chi }\chi$ decays, where $\chi$ is a fermionic dark matter candidate. The effective $Z\chi \chi$ coupling is generated radiatively through one-loop diagrams involving the top quark and a new colored scalar. We show that dark photons produced via this dark radiation channel can dominate over the conventional sources-meson decays and proton bremsstrahlung-across wide regions of parameter space, particularly for small kinetic mixing and dark photon masses well above the GeV scale. Using this enhanced production mechanism, we analyze the sensitivity of dedicated long-lived particle detectors, including FASER2, FACET, and MATHUSLA. We find that these experiments can significantly surpass existing bounds, probing regions of dark photon parameter space consistent with the observed dark matter relic abundance and inaccessible in conventional dark photon scenarios.

    hep-ph0 citations
11. 11*

    DD-pair production in the parton Reggeization approach taking into account single and double parton scattering scenarios

    Lev Alimov🇷🇺 · Vladimir Saleev🇷🇺

    The paper presents the results of calculations of the cross sections for the production of $DD$-pairs at centre-of-mass energies $\sqrt{s}=7$ and $13$ TeV in the parton Reggeization approach. The contribution of both single and double parton scattering is taken into account. To describe the non-perturbative effects of $c$-quark hadronization into $D$-mesons, a fragmentation model with the Peterson fragmentation function is used. The parameter ${\sigma }_{eff}=11.5_{-0.5}^{+0.6}$ mb, which determines the contribution of the double parton scattering mechanism, is fixed on the basis of a comparison with the available LHCb collaboration experimental data on the $D$-meson pairs production at $\sqrt{s}=7$ TeV.

    hep-ph0 citations
12. 12*

    Toward a Community Roadmap for High Energy Physics and Artificial Intelligence in China and Beyond

    Tianji Cai🇺🇸 · Ke Li🇨🇳 · Teng Li🇨🇳

    Artificial Intelligence (AI) is rapidly transforming scientific research and has become central to many data-intensive disciplines. High Energy Physics (HEP), with its vast data volumes, complex theoretical structures, and precision-driven methodologies, lies at a particularly fertile intersection with modern AI. In this document, we present a community-informed overview of AI+HEP development in China and beyond, motivated in part by discussions at the 2025 Quantum Computing and Machine Learning Workshop in Qingdao, Shandong Province. We briefly review current AI activities across experimental, phenomenological, and theoretical HEP, along with key aspects of the research ecosystem. This work does not aim to represent the entire community, but rather reflects a partial and evolving snapshot informed by discussions and perspectives gathered from members of the broader AI+HEP community. We hope it serves as an initial roadmap to inform future coordinated efforts and to lay the groundwork for a more comprehensive community white paper.

    hep-phhep-exhep-th2 citations
13. 13*

    Self-Interaction Bounds on Ultralight Dark Matter Couplings to Matter

    Mohammad Aghaie🇯🇵 · Shao-Ping Li🇦🇹

    Ultralight dark matter (ULDM) couplings to matter fields and ULDM self-interactions are typically treated as independent probes. However, since the ULDM-matter couplings unavoidably induce self-interactions through quantum loop corrections, bounds on self-interacting ULDM from astrophysical and cosmological observations will also limit the coupling strength to matter. Applying this argument, we find that self-interaction bounds can impose strong constraints on the linear ULDM couplings to neutrinos, excluding a large portion of parameter space that is widely considered for probing ULDM via neutrino oscillation experiments. In addition, the self-interaction bounds also limit the quadratic ULDM couplings to electrons and light quarks, which can become stronger than from the stringent test of equivalence-principle violation. Our results demonstrate that the extreme observational sensitivity of cosmic microwave background and structure formations to repulsive self-interactions can robustly translate into powerful constraints on the ULDM interactions with fundamental particles.

    hep-phastro-ph.CO1 citation
14. 14*

    Non-Markovian Electroweak Baryogenesis: Memory Effects on CP-Violating Transport and Gravitational Waves

    Arnab Chaudhuri🇮🇳

    We develop a non-Markovian extension of electroweak baryogenesis within the Schwinger--Keldysh real-time effective field theory framework and the Kadanoff--Baym hierarchy. When the relaxation time of CP-violating mediators becomes comparable to the bubble-wall crossing time, transport dynamics acquire temporal nonlocality, leading to memory-kernel corrections to the CP-violating source and diffusion equations beyond the Markovian approximation. These effects shift the optimal wall velocity to smaller values, narrow the viable parameter space, and induce a characteristic non-monotonic dependence of the baryon asymmetry on the memory timescale for sub-optimal wall velocities, which cannot be reproduced by a consistent Markovian reparameterisation. A systematic parameter analysis identifies regions compatible with the observed baryon asymmetry and constrains the allowed memory timescale from hydrodynamic stability and the physical range of the CP-violating phase. We also assess the correlated impact on the stochastic gravitational-wave signal, finding that memory effects can enhance the effective source duration and amplitude, although much of the viable parameter space remains below near-future detector sensitivities and theoretical uncertainties remain at the order-of-magnitude level. These results establish non-Markovian transport as a well-motivated extension of electroweak baryogenesis and introduce the memory timescale as a parameter testable through baryon asymmetry measurements, collider CP probes, and gravitational-wave observations.

    hep-ph0 citations
15. 15*

    Role of $a_0(1710)$ in the $J/\psi \to {\rho }^{+}{\rho }^{-}\omega$ and $J/\psi \to \gamma {\rho }^0\omega$ reactions

    Wen-Tao Lyu🇨🇳 · Luis Roca🇪🇸 · Eulogio Oset🇪🇸

    We investigate the strong decay $J/\psi \to {\rho }^{+}{\rho }^{-}\omega$ and the radiative decay $J/\psi \to \gamma {\rho }^0\omega$, taking into account the $S$-wave $K^{\ast }{\bar{K}}^{\ast }$, $\rho \omega$ and $\rho \varphi$ final-state interactions, which dynamically generate the scalar meson $a_0(1710)$. Our results demonstrate that a clear peak structure emerges around 1.8~GeV in the ${\rho }^{+}\omega$~(${\rho }^{-}\omega$) invariant mass distribution of the strong decay, which can be associated with the $a_0(1710)$ resonance. Similarly, a distinct peak is predicted in the ${\rho }^0\omega$ invariant mass distribution of the radiative decay. Our results indicate that clear signals of $a_0(1710)$ production could be observed in future measurements of these processes at BESIII, Belle II, and the planned Super Tau-Charm Facility, thereby helping to determine its mass and width more precisely.

    hep-phPRD(2026)·0 citations
16. 16*

    Dark Matter Production from Bubble Collisions during a First-Order Phase Transition at the End of Inflation

    Zihong Cheng🇨🇳 · Fa Peng Huang🇨🇳

    We study whether a first-order phase transition at the end of inflation can generate the observed dark matter abundance through bubble collisions. The transition occurs in a spectator scalar sector with an inflaton-dependent effective potential, so that the nucleation rate grows during inflation and becomes significant only near its end. We identify the region of parameter space in which vacuum decay is dominated by the Coleman--De~Luccia channel, the Hawking--Moss transition remains subdominant, and the nucleated bubbles admit a consistent physical interpretation in an inflating background. Requiring also that the phase transition completes successfully, we then analyze particle production from bubble collisions. In the viable regime, elastic self-scatterings of the spectator particles can efficiently redistribute their momenta, while their decay into dark matter provides the dominant channel for transferring the spectator population to the dark sector. Other competing number-changing or sink processes remain inefficient compared with the Hubble expansion. The final relic abundance receives contributions from both direct production in bubble collisions and the subsequent decay of spectator field particles. We find that the observed dark matter abundance can be accommodated, within the order-of-magnitude accuracy of the collision-production treatment, in a restricted region of parameter space.

    hep-ph4 citations
17. 17*

    Exclusive photoproduction of a di-meson pair with large invariant mass

    Saad Nabeebaccus🇫🇷 · David Perez🇫🇷 · Lech Szymanowski🇵🇱 · Samuel Wallon🇫🇷

    The exclusive photoproduction of a pair of light mesons is studied within the framework of collinear factorisation. The amplitude factorises into a process-dependent perturbatively calculable hard part, a generalised parton distribution (GPD) and two distribution amplitudes (DAs). We focus on the production of any combination of $\rho$ and $\pi$ mesons (of any charge and polarisation) that do not involve neutral $C=+$ exchanges with the nucleon. This gives a total of 26 distinct channels, which are sensitive to quark GPDs only. We calculate the amplitude for this family of di-meson processes at leading order in the strong coupling constant ${\alpha }_s$ and at leading twist, in a fully-automated way. Depending on the choice of mesons in the final state, some of these processes are sensitive to chiral-odd (helicity-flip) GPDs. Particular attention is given to the treatment of poles in the 3-dimensional convolution integral of the momentum fractions connecting the hard part with the different non-perturbative components. These poles are regularised by the usual Feynman $iϵ$ factors, but lead to numerical instabilities if not dealt with properly. We also discuss in detail the construction of the phase space. Importantly, we propose a resolution for the inconsistency of the kinematics of the hard part of the process, where hadron masses and other soft scales are neglected, with the rest of the process. As a proof of concept, we explicitly evaluate the cross section, for a subset of processes whose amplitudes have been constructed, at energies typical of the CLAS12 experiment at JLab. Our results indicate that exclusive di-meson photoproduction processes have very good statistics, which can be a factor of up to a hundred more than the exclusive photon-meson photoproduction process. Therefore, the family of processes that we study here represents a great opportunity for GPD extraction.

    hep-phhep-exnucl-exnucl-th0 citations
18. 18*

    Properties and implications of the four-loop non-singlet splitting functions in QCD

    S. Moch (Hamburg U., Inst. Theor. Phys. II)🇩🇪 · A. Vogt (Liverpool U., Dept. Math.)🇩🇪

    We have studied the recently completed analytic all-N expressions for the four-loop anomalous dimensions corresponding to the next-to-next-to-next-to-leading order splitting functions for the non-singlet quark distribution in perturbative QCD. The results agree with fixed-N values beyond those published so far. Their structural consistency with theoretical requirements is established. They are used to cast the four-loop gluon virtual anomalous dimension and the next-to-next-to-next-to-next-to-leading logarithmic threshold-resummation coefficients for lepton-pair and Higgs production in hadron-hadron collisions and deep-inelastic scattering into their final analytical forms. Further properties and consequences of the new results are addressed, in particular a new structure seen most clearly in the small-x logarithms occurring in a quartic-Casimir contribution.

    hep-ph1 citation
19. 19*

    QCD sum rules: Borel parameter vs. Euclidean time

    A.V. Smilga🇫🇷

    We explore a modification of QCD sum rules where, instead of Borel transforms of current correlators, one considers the correlators in coordinate space as functions of Euclidean time. Taking the nucleon channel as an example, we derive such Euclidean time sum rules and compare them with the traditional Borel sum rules. We show that a rough estimate of nucleon mass and residue is also possible working in coordinate space, but such sum rules are much more affected by the uncertainties in power corrections and continuum contribution than the Borel ones: the fiducial interval is practically absent.

    hep-phhep-th0 citations
20. 20*

    Two-loop leading-color QCD corrections for Higgs plus two-jet production in the heavy-top limit

    Giuseppe De Laurentis🇬🇧 · Harald Ita🇨🇭 · Viktor Kuschke🇨🇭 · Michael Ruf🇺🇸 · Vasily Sotnikov🇨🇭

    We present the leading-color two-loop QCD corrections for Higgs-boson production in association with two jets through gluon fusion in the heavy-top effective theory. We provide analytic expressions for the finite remainders of the helicity amplitudes, written in terms of one-mass pentagon functions with spinor-helicity coefficients. These expressions are obtained by reconstructing the amplitudes from numerical finite-field samples computed within the numerical unitarity framework. The reconstruction is made possible by several advances in exploiting the analytic structure of the amplitudes, which both reduce the number of required samples and lead to compact representations. In particular, we introduce a new algorithm for multivariate partial fraction decomposition, based on a generic bivariate slice and a simplified treatment of ideal intersections. Using the resulting analytic expressions, we provide an efficient and stable implementation of their numerical evaluation, ready for phenomenological applications. Finally, we study the singularity structure of the remainders and confirm the existence of a threshold at non-degenerate physical momentum configurations, usually associated with massive virtual particle exchanges.

    hep-phhep-thJHEP(2026)·4 citations
21. 21*

    Real and Complex Singlet-Scalar Benchmarks with a Vector-Like Down Quark for $B\to X_s\gamma$ and $B_s-{\bar{B}}_s$ Mixing

    Qazi Maaz Us Salam🇵🇰

    We study a simple extension of the Standard Model with a vector-like down-type quark $D$ and a neutral singlet scalar $\mathcal{S}=S_R,\Phi$. The scalar is considered in two forms, a real field $S_R=S_R^{†}$ and a complex field $\Phi \ne {\Phi }^{†}$. The interaction $-{\lambda }_i\mathcal{S}{\bar{D}}_L{d}_{Ri}+h.c.$ generates the radiative transitions $b\to s\gamma$ and $b\to sg$ at one loop. Since $\mathcal{S}$ has no electric charge or color, the gauge boson is emitted from the internal $D$ line, giving $C_{7\gamma }^{\mathrm{NP}}/C_{8G}^{\mathrm{NP}}=Q_D=-1/3$ at the matching scale for $\Delta B=1$ dipole transitions. For $M_D=m_{\mathcal{S}}=1\mathrm{TeV}$ and $|{\lambda }_s^{\ast }{\lambda }_b|=1$, the low scale contribution is $|C_{7\gamma }^{\mathrm{NP},\mathrm{eff}}({\mu }_b)|\simeq 1.1\times 10^{-3}$, This is about $0.4\%$ of the Standard Model value $|C_{7\gamma }^{\mathrm{SM},\mathrm{eff}}({\mu }_b)|\simeq 0.30$. We also discuss \(B_s-\bar B_s\) mixing. In the real-scalar case, the direct and crossed box diagrams cancel in the exact minimal limit. In the complex-scalar case, the direct box contribution remains and gives a bound on the flavor $|{\lambda }_s^{\ast }{\lambda }_b|$ at the level of a few tenths for TeV-scale masses. Thus, in these minimal benchmarks, $B\to X_s\gamma$ is radiatively safe, while $B_s-{\bar{B}}_s$ mixing gives the stronger constraint in the complex-scalar $\Phi$ benchmark.

    hep-phEPJC(2026)·0 citations
22. 22*

    Predictions for the scalar partner of the LHC tetraquark $X(6600)$

    Muhammad Naeem Anwar🇬🇧 · Timothy J. Burns🇬🇧

    We consider how the recent CMS measurements of the masses and quantum numbers of $X(6600)$, $X(6900)$ and $X(7100)$ can help to reveal the internal structure of these apparent $cc\bar{c}\bar{c}$ tetraquark states. The measured $J^{PC}=2^{++}$ quantum numbers of $X(6600)$ are consistent with our previous prediction, and imply the existence of lighter $0^{++}$ partner $X(6400)$ which also decays to $J/\psi J/\psi$. There may already be indications for this scalar partner in the recent CMS data fits, which include a Breit-Wigner peak with mass around 6400~MeV. We give predictions for the masses and decay properties of the scalar and other partner states, which are key experimental tests to discriminate between quark and diquark models. We urge closer experimental scrutiny in this mass region, to establish an S-wave multiplet of $cc\bar{c}\bar{c}$ states (the first of its kind), leading to a breakthrough in exotic hadron research and our understanding of exclusively heavy quark exotics.

    hep-phhep-exhep-lat1 citation
23. 23*

    Covariant Spinor Formalism for Multipole Expanded Form Factor

    Hong Huang🇨🇳 · Tuo Tan🇨🇳 · Yi-Ning Wang🇨🇳 · Jiang-Hao Yu🇨🇳

    We present a systematic technique for constructing Lorentz covariant orbital-spin ($LS$) bases for matrix elements of local operators and the associated form factors, thereby extending the traditional multipole expansion to a Lorentz covariant formalism. In the spinor-helicity formalism, matrix elements of local operators for spin-$j$ particles can be treated as several massive 3-point scattering amplitudes, each of which can be further decomposed into different $LS$ partial wave amplitudes. We obtain explicit complete and linearly independent $LS$ amplitude bases for scalar, vector, and rank 2 tensor form factor of particles with spin-$\frac{1}{2}$, $1$, and $\frac{3}{2}$. In the Breit frame, it recovers the traditional multipole expansion expression, and we show the explicit equivalence among the traditional multipole expansion, canonical $LS$ expansion, and the $\mathrm{SO}(3)$ Zemach tensor expansion. Finally noting covariant structures built from the relativistic external wave functions and momenta of the initial and final state particles, we give a universal construction formula for form factor of arbitrary Lorentz tensor operators for arbitrary external spin particles.

    hep-ph0 citations
24. 24*

    On the magnetic counterpart of the Uehling correction

    T. Azevedo🇧🇷 · F.A. Barone🇧🇷 · C. Farina · R. de Melo e Souza · G. Zarpelon

    In this work, we investigate the magnetic properties of the quantum vacuum in the context of QED. We calculate the quantum relativistic correction of virtual particle--anti-particle pair creation to the field of a classical point-like idealized magnet. Using such correction, we find the induced currents stemming from the effect of the polarization of the vacuum, which behaves like a paramagnetic medium. We also calculate the correction to the electric dipole potential and show that the well-known symmetry between the classical fields of point electric and magnetic dipoles is broken at the quantum level. Lastly, we apply the corrections to calculate the contributions of the hyperfine structure in a simple hydrogen-like atom.

    hep-phhep-th0 citations
25. 25*

    CP asymmetries in charged meson decay to two pions

    Yuval Grossman🇺🇸 · Zoltan Ligeti🇺🇸 · Yosef Nir🇮🇱

    We study the CP asymmetries in $B^{+}$, $D^{+}$, and $K^{+}$ decays into ${\pi }^{+}{\pi }^0$. These asymmetries are commonly known to vanish in the isospin limit. We clarify what is meant by the term ``isospin limit" in this context. We provide a unified formalism to discuss these asymmetries, and develop an understanding of how various suppression factors distinguish between them qualitatively. We estimate the size of the asymmetries in the Standard Model: $A_{CP}(B^{+}\to {\pi }^{+}{\pi }^0)\sim 3\times 10^{-3}$, $A_{CP}(D^{+}\to {\pi }^{+}{\pi }^0)\sim 10^{-5}$, and $A_{CP}(K^{+}\to {\pi }^{+}{\pi }^0)\sim 10^{-6}$

    hep-ph2 citations
26. 26*

    Composite top partners in exotic colour representations

    Giacomo Cacciapaglia🇫🇷 · Rosy Caliri🇩🇪 · Aldo Deandrea🇫🇷 · Benjamin Fuks🇫🇷 · Mark Goodsell🇫🇷 · Jan Hadlik🇩🇪 · Manuel Kunkel🇩🇪 · Werner Porod🇩🇪

    Composite Higgs models with partial compositeness generically predict coloured fermionic resonances associated with the strong dynamics responsible for electroweak symmetry breaking. While most phenomenological studies have focused on colour-triplet and colour-octet top partners, several UV-complete hypercolour constructions also contain fermionic colour sextets. We present a systematic study of these states in the minimal model classes where they arise, constructing the relevant low-energy interactions and deriving their characteristic decay patterns. The sextets predominantly decay through coloured pseudo-Nambu-Goldstone bosons, leading to top-rich final states, while additional channels with $b$-jets and missing transverse energy can be important. We reinterpret existing ATLAS and CMS searches for high-multiplicity final states to derive the dedicated constraints on these resonances. For the benchmark spectra considered, current LHC data exclude individual sextet components up to masses in the $2-2.5$ TeV regime, with stronger bounds when the full sextet multiplet is included, while conservative extrapolations to the HL-LHC indicate a reach close to $3$ TeV. Our results therefore show that colour-sextet fermions provide a powerful and largely unexplored probe of composite Higgs models with partial compositeness.

    hep-phhep-ex3 citations
27. 27*

    Proton-Proton to Antinucleon Cross Sections for Cosmic Ray Applications

    Mariaelena Boglione🇮🇹 · Mattia di Mauro🇮🇹 · Fiorenza Donato🇮🇹 · Emanuele R. Nocera🇮🇹 · Jennifer Rittenhouse West🇮🇹 · Andrea Signori🇮🇹

    We present predictions of inclusive antiproton and antineutron production cross sections in proton-proton collisions relevant to primary and secondary antiproton production in cosmic ray interactions with interstellar matter. Our predictions are based on collinear factorisation in Quantum Chromodynamics and are accurate to next-to-leading order in the perturbative expansion of the strong coupling. We assess the relevance of cross sections measured at collider experiments, such as NA49 at the CERN SPS and ALICE at the LHC, to the kinetic energy ranges accessed by cosmic ray detectors. We characterise the associated uncertainties due to the input parton distribution and fragmentation functions, and to missing higher orders. We critically examine the ~30% excess of antineutron over antiproton production in proton-proton collisions preliminarily reported by the NA49 experiment by combining our predictions with a data-driven model. Our results do not support the NA49 finding, and point to a mild excess of a few percent. We finally show that the NA49 result could only be reconciled with our framework by invoking sizeable differences between antiproton and antineutron production in the poorly constrained region of small transverse momenta of the produced hadron.

    hep-phastro-ph.HEhep-ex1 citation
28. 28*

    Squeezed-state radiation in shockwave scattering: QCD-Gravity double copy

    Anna M. Staśto🇺🇸 · Himanshu Raj🇺🇸 · Raju Venugopalan🇺🇸

    Gluon and graviton radiation in strong field shockwave scattering are described by effective Lipatov vertices, with the graviton Lipatov vertex proportional to the bilinear of its QCD counterpart. We show here that the n-particle gluon radiation spectrum can be described as a generalized Susskind-Glogower (gSG) squeezed coherent state and discuss the properties of such squeezed states. The double copy structure of the radiative frameworks suggests that multi-graviton radiation can be similarly described as a gSG state. We examine the physical parameter space and show that very large squeezing parameters $\sim \ln (\bar{n})$ (where $\bar{n}$ is the mean graviton occupancy) are feasible for nearly minimal uncertainty configurations of the gSG state. Quantum noise in the corresponding gravitational wave spectrum is enhanced above the sensitivity of current and future gravitational wave detectors. Our results point to the importance of a comprehensive study of the strong field Lipatov regime of gravitational radiation.

    ↳ hep-thgr-qchep-phnucl-thActa Phys.Polon.B(2026)·1 citation
29. 29*

    Pseudo-Evanescent Feynman Integrals from Local Subtraction

    Alessandro Georgoudis🇬🇧 · Ben Page🇧🇪

    We introduce a new approach for the computation of the class of Feynman integrals whose integrands vanish in strictly four-dimensions, so-called ''pseudo-evanescent'' integrals. We argue that, up to $\mathcal{O}(ϵ)$ corrections, local subtraction techniques can be used to express pseudo-evanescent integrals in terms of contributions from infrared and ultraviolet regions of loop-momentum space. We study two-loop examples and find that many pseudo-evanescent Feynman integrals are reduced to either products of one-loop integrals or one-fold integrals thereof. As a demonstration of the power of our approach, we use it to recompute the two-loop all-plus five-point amplitude. We find that, up to scheme-dependent logarithms, all contributions from soft and collinear regions cancel exactly against known infrared structure and that the finite remainder is entirely given by contributions from ultraviolet regions.

    ↳ hep-thhep-phJHEP(2026)·2 citations
30. 30*

    Primordial high energy neutrinos

    Nicolas Grimbaum Yamamoto🇧🇪

    Among the few ways to probe the early Universe, neutrinos offer a particular window on high energy phenomena occurring before recombination. We discuss the opportunities of observing primordial high energy neutrinos (Phenus): neutrinos produced before or around recombination from the decay or annihilation of long-lived relics, arriving at detectors today with energies in the GeV-PeV range. We summarise the results of a general study of this scenario, covering the sharp spectral features such fluxes would display, the theoretical (BBN and CMB) and experimental constraints on the source particle parameter space, and the regions that could realistically be probed by current and future neutrino telescopes. We also present a dedicated Monte Carlo code for computing the distortion of the Phenu spectrum by final state radiation and interactions with the cosmic neutrino background during propagation, and apply it to assess the primordial origin hypothesis for the KM3-230213A ultrahigh energy neutrino event.

    ↳ astro-ph.HEhep-ph0 citations
31. 31*

    Resonances as signatures of scalar clouds in eccentric extreme-mass-ratio inspirals

    Qi-Xuan Xu🇵🇹 · Richard Brito🇵🇹 · Riccardo Della Monica🇵🇹 · Rodrigo Vicente🇳🇱 · Chen Yuan🇵🇹

    Ultralight scalars arise naturally in many extensions to the Standard Model and are compelling dark matter candidates. Around spinning black holes, dense scalar clouds could form through the conversion of rotational energy into particles via black hole superradiance. Extreme-mass-ratio inspirals (EMRIs) targeted by future space-based detectors will give us unparalleled access to the environments of massive black holes, allowing us to probe the presence of scalar clouds. We consider EMRIs around a Schwarzschild black hole and show that eccentricity induces a dense sequence of resonances in the scalar fluxes near the last stable orbit. These resonances arise only in a fully relativistic treatment, as they are intrinsically tied to the splitting between the azimuthal and radial orbital frequencies in the strong-field regime. By evolving the orbits adiabatically, we show that the resulting resonant transitions substantially enhance the exchange of energy and angular momentum between the EMRI and the scalar cloud, significantly amplifying the accumulated dephasing in the gravitational waveform relative to circular motion. Our results highlight the importance of eccentricity in shaping the observational signatures of EMRIs embedded in scalar clouds.

    ↳ gr-qcastro-ph.HEhep-ph7 citations
32. 32*

    Reply to Comment on "Controlling the Dynamical Evolution of Quantum Coherence and Quantum Correlations in $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$ Processes at BESIII"

    Elhabib Jaloum🇲🇦 · Mohamed Amazioug🇲🇦

    In the annihilation process $e^{+}{e}^{-}\to J/\psi \to \Lambda \bar{\Lambda }$ via $J/\psi$, the hyperon--antihyperon pair emerges from the same non-perturbative QCD hadronization process, where both spins develop in a common dense partonic environment. We describe the evolution of the $\Lambda \bar{\Lambda }$ spin degrees of freedom using correlated quantum channels that represent the effective influence of the common QCD hadronization environment on the two-spin system. The parameter $\mu$ characterizes the degree of environmental correlation resulting from the common hadronization process. Using the experimentally reconstructed spin density matrix, we evaluate quantum steering and investigate its robustness and dynamical evolution under correlated Markovian and non-Markovian quantum channels.

    ↳ quant-phhep-ph0 citations
33. 33*

    Constraining F-theory Model Building with QCD Axions

    Keren Chen🇨🇳 · Qinjian Lou🇨🇳 · Yi-Nan Wang🇨🇳

    In this paper, we investigate axion physics in 4D F-theory MSSM models. We derive the axion coupling term with QCD gauge fields and the axion potential from a top-down perspective, from both IIB superstring and the dual M-theory picture. For the explicit geometric model, we employ the "quadrillion" landscape of 4D F-theory models with the exact Standard Model chiral spectrum, and study simple base threefolds such as ${\mathbb{P}}^3$, ${\mathbb{P}}^1\times {\mathbb{P}}^2$, the generalized Hirzebruch threefold ${\tilde{\mathbb{F}}}_3$ and ${\mathbb{P}}^1\times {\mathbb{P}}^1\times {\mathbb{P}}^1$. We derive exclusion constraints on the Kähler moduli space of the base threefold from the CP violation angle, the Standard Model gauge coupling constants and the stretched Kähler cone condition. We find stringent constraints on the set of base divisors that should be rigid or rigidified by the inclusion of flux. For the allowed regions of the parameter space, we estimate the typical mass of detectable QCD axions to be around $10^{-9}$eV, and the axion decay constant to be around $f_a\sim 10^{15}$GeV.

    ↳ hep-thhep-ph2 citations
34. 34*

    Nonlinear Compton scattering in a frequency-modulated field

    Antonino Di Piazza🇺🇸 · Kenan Qu🇺🇸

    When an electron is accelerated, it emits radiation. In the relativistic quantum realm the elementary radiation process is the emission of a single photon, a process known as nonlinear Compton scattering in the case of an electron moving in the presence of a strong electromagnetic wave. This process is typically described within the Furry picture, where the electromagnetic wave is described as a classical background field and the electron-positron field is quantized in the presence of that background field. Equivalently one can quantize the electron-positron field in the vacuum but then the photon emission process is described as a transition from an initial state to a final state both featuring, apart from the electron (the initial state) and the electron and the photon (the final state), the same coherent state of photons appropriately related to the electromagnetic wave. Here, we consider a more general situation where the initial and the final state feature the same squeezed coherent state. Then, we specialize to the case where the coherent state corresponds to a plane-wave field and the mostly populated modes of the coherent state are also squeezed. We show that, when quantum fluctuations induced by the squeezing in the coherent field are negligible, a condition well satisfied at available squeezing levels, the squeezing effects effectively reduce to a frequency modulation of the plane-wave field corresponding to the coherent state. By means of numerical examples we show that at already available squeezing levels the emission spectrum of nonlinear Compton scattering and the total photon yield can be altered significantly. Analytical explanations of the main numerical results are also provided.

    ↳ quant-phhep-ph1 citation
35. 35*

    Late-Time Relaxation from Landau Singularities

    Dong-Lin Wang🇨🇳 · Shi Pu🇨🇳

    Nonlinear hydrodynamic interactions can change the relaxation of fluctuations from exponential to power-law decay at late times. Schwinger-Keldysh effective field theory provides a standard framework for describing such fluctuation effects, where the nonlinear late-time behavior is encoded in loop corrections. Extracting this behavior requires identifying the singularities of loop integrals, whose structure becomes increasingly intricate beyond simple models. We apply Landau singularity analysis to two-point functions in effective field theories and determine the singularities induced by nonlinear interactions without performing the loop integrations explicitly. From these frequency-space singularities, we extract nonlinear relaxation modes that control the late-time behavior. When gapless modes are present, these modes produce power-law decay at late times. Our results give a systematic singularity-based description of nonlinear late-time relaxation in a broad class of macroscopic effective theories.

    ↳ hep-thcond-mat.stat-mechhep-phnucl-th0 citations
36. 36*

    Heterotic String Theory Suggests a QCD Axion Near 0.5 neV

    Joshua N. Benabou🇺🇸 · Giulio Alvise Dainelli🇺🇸 · Mario Reig🇨🇭 · Benjamin R. Safdi🇺🇸

    We show that in heterotic string theory -- and dual corners of the landscape including Type I string theory -- the QCD axion mass is bounded from below by $m_a\gtrsim 0.5$ neV, a direct consequence of the model-independent axion whose decay constant is fixed by the grand unified theory (GUT) gauge coupling. We explicitly compute the mass of the QCD axion in an ensemble of heterotic compactifications on Calabi-Yau hypersurfaces of toric varieties sampled from the Kreuzer-Skarke (KS) ensemble, as well as on complete intersection Calabi-Yau manifolds. We then perform an extensive search over the Kähler moduli space of KS compactifications with up to $11$ axions -- the maximum we identify as consistent with unification in our sample. We establish that for all but a handful of manifolds the QCD axion mass is precisely the model-independent value, lying in $[0.5,0.8]$ neV, depending on the GUT gauge coupling. This window should be a high-priority target for future lumped-element detectors such as DMRadio-GUT. We show that the heavy axion population in our heterotic ensemble generically decays before big bang nucleosynthesis and can naturally accommodate leptogenesis, unlike in Type IIB axiverse constructions.

    ↳ hep-thhep-ph6 citations
37. 37*

    (Pseudo-)Dirac Gravitinos

    Karim Benakli🇫🇷 · Arno Goudeau🇫🇷

    We discuss low-energy effective theories with a Dirac gravitino. Our main benchmark is Scherk--Schwarz supersymmetry breaking with anti-periodic boundary conditions for fermions on S^1/Z_2. In this case two Majorana spin-3/2 modes are degenerate, so the low-energy theory is naturally organized around a Dirac gravitino and an associated R-symmetry selection rule. We show, in minimal supergravity, that this Dirac spin-3/2 mixing has no local Dirac-gaugino-type N=1 superspace realization: a superspace description requires projection onto the transverse superspin-3/2 sector. We then analyze some consequences for matter couplings and radiative masses. The ordinary gravitino supercurrent coupling gives the standard universal Scherk--Schwarz scalar threshold; in the minimal benchmark this contribution is negative, and should therefore be regarded as one calculable contribution to the scalar mass matrix, not as a complete scalar-spectrum prediction. Dirac fermion masses can be generated if an additional companion-channel matter current is present. The existence and normalization of this current are not fixed by the Dirac gravitino alone and depend on the ultraviolet completion. We finally discuss small R-breaking deformations, the resulting pseudo-Dirac regime, and comment on possible applications to singlet fermions, modulini, and radiative Dirac neutrino masses.

    ↳ hep-thhep-phJHEP(2026)·0 citations
38. 38*

    Heterotic Flux Vacua with a Small Superpotential

    Evgeny I. Buchbinder🇦🇺 · Andrei Constantin🇬🇧 · Lucas T. Y. Leung🇬🇧 · Andre Lukas🇬🇧 · Burt Ovrut🇺🇸

    We study heterotic Calabi--Yau compactifications with NSNS three-form flux in view of moduli stabilisation and investigate whether the value $|W_0|$ of the flux superpotential evaluated at supersymmetric minima can be small. Unlike in type IIB string theory, heterotic compactifications lack a no-scale structure, so that a non-vanishing flux superpotential generically induces a tree-level scalar potential for all moduli. Controlled moduli stabilisation therefore requires the flux superpotential to be sufficiently small in order to compete with non-perturbative effects. Working within a four-dimensional effective field theory and exploiting the special geometry of Calabi--Yau complex structure moduli spaces, we analyse the complex structure F-term equations and derive two no-go theorems: (1) supersymmetric vacua with vanishing $|W_0|$, which would lead to a vanishing tree-level scalar potential as in type IIB, occur only at singular loci in moduli space, and (2) no supersymmetric vacua with small $|W_0|$ exist in the large complex structure limit. Motivated by these results, we analyse explicit models away from the large complex structure regime using exact period expressions and identify one- and two-parameter examples in which suitable flux choices allow for values of $|W_0|$ of order unity, with some one-parameter models admitting values moderately below unity. Our findings show that small heterotic flux superpotentials are highly constrained, with the values of $|W_0|$ found in the examples studied being only marginally compatible with moduli stabilisation.

    ↳ hep-thhep-ph0 citations
39. 39*

    Consistent Scattering Amplitudes, Yang-Mills, the Higgs Mechanism and the EFTs Beyond

    Timothy Trott🇺🇸

    I study constraints on fundamental physics emerging from consistency of a unitary, local and perturbative $S$-matrix in $4d$. For massless particles, some new constraints arising from consistent complex factorisation of $2\to 2$ amplitudes are derived, leading, in particular, to the complete structure of the gluon three-particle amplitudes, including the geometric restrictions on the Lie algebra, parity and time-reversal symmetry, among other details. For massive particles, a hierarchy of constraints may be derived instead by imposing a maximum rate of unitarity-violating growth in the high energy limit. All $2\to 2$ tree-level amplitudes of massive particles with spin $s\le 1$ are calculated in generality using on-shell methods and presented with manifest high energy dependence. The anatomy of these amplitudes' helicity sectors is dissected in order to identify conditions under which their energy growth is limited or eliminated. Using these results, it is shown that the scattering of massive vector bosons has suppressed, but not fully unitarised, high energy dependence if the parity-conserving parts of their self-couplings are Lie algebra structure constants, possibly non-semisimple or non-compact, and the parity-violating parts are ``generalised Chern-Simons terms''. Full unitarisation then requires the standard Yang-Mills Lie algebra properties and, for a gapped spectrum, the Higgs mechanism. These amplitudes are assembled, embedded and unified into elegant superamplitudes in theories with extended supersymmetry when the particles are BPS. More generally, a broader landscape of EFTs is charted through various combinations of constraints and coupling hierarchies.

    ↳ hep-thhep-ph1 citation

* 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.