Fri·May 2, 2025Friday·May 2, 2025

1. 01*

   Spin Correlations in $t\bar{t}$ Production and Decay at the LHC in QCD Perturbation Theory

   Paolo Nason🇮🇹 · Emanuele Re🇮🇹 · Luca Rottoli🇮🇹

   In this work we consider the QCD predictions for spin correlations in $t\bar{t}$ production in hadronic collisions. In view of recent tensions between experimental data and theoretical calculations, it has been argued that one should include in the predictions also the effects of the production of the ${\eta }_t$, i.e. the pseudoscalar $t\bar{t}$ bound state, or alternatively the full effects of the non-relativistic dynamics of the $t\bar{t}$ pair near threshold. This implies the resummation of all corrections that scale like powers of ${\alpha }_s/v$ (where $v$ is the velocity of the top quark in the $t\bar{t}$ rest frame) which are dominated by values of $v$ of order ${\alpha }_s$. In this work, we show that, since the observables that are usually considered for these studies are integrated cross sections up to a $t\bar{t}$ mass cut that is not small, it is possible to perform the calculation using perturbation theory, considering only the contributions that scale as the first few powers of ${\alpha }_s/v$. We examine the implications of our approach by computing corrections to nominal Monte Carlo results for correlation-sensitive observables, and compare them with available data, showing that the tension with data is no longer present.

   hep-phhep-exJHEP(2025)·32 citations
2. 02*

   Quarkonia Theory: From Open Quantum System to Classical Transport

   Xiaojun Yao🇺🇸

   This is a theoretical overview of quarkonium production in relativistic heavy ion collisions given for the Hard Probes 2024 conference in Nagasaki. The talk focuses on the application of the open quantum system framework and the formulation of the chromoelectric correlator that uniquely encodes properties of the quark-gluon plasma relevant for quarkonium dynamics and thus can be extracted from theory-experiment comparison.

   hep-phnucl-thquant-phEPJ Web Conf.(2025)·2 citations
3. 03*

   Goofy is the new Normal

   Andreas Trautner🇩🇪

   We discuss the recently discovered global $\text{goofy}$ transformations and conclude that their understanding is mandatory to describe the renormalization group (RG) fixed point structure of quantum field theories (QFTs) in general. Originally, goofy transformations were identified in the two-Higgs-doublet model (2HDM), where their surprisingly RG stable parameter relations do not correspond to any $\text{regular}$ symmetry. We unveil several new goofy transformations and their associated RG fixed points, which we have explicitly checked to be RG invariant to three-loop order in gauge-, and scalar quantum corrections. We give a general argument as to why the implied parameter relations are RG invariant to all orders, even though the corresponding goofy transformations are explicitly broken by the gauge-kinetic terms. Goofy transformations can prohibit bare scalar mass parameters and give rise to generation-dependent sensitivity on relative signs of gauge couplings, for what reason they may have important applications for the electroweak hierarchy problem and the Standard Model flavor puzzle. We also discuss the relevance of goofy-symmetric RG fixed points for a phenomenon of "dynamical classicalization" in QFT.

   hep-phhep-thJHEP(2025)·13 citations
4. 04*

   Neutrino masses and mixed dark matter from doublet and singlet scalars

   Jongkuk Kim🇰🇷 · Seong-Sik Kim🇰🇷 · Hyun Min Lee🇰🇷 · Rojalin Padhan🇰🇷

   We consider the extension of the Standard Model with an inert scalar doublet, three right-handed neutrinos, and singlet scalar fields, $\phi$ and $S$. In this model, neutrino masses are zero in the limit of the unbroken $Z_4$ discrete symmetry. We show that when the singlet scalar field $\phi$ gets a VEV, the $Z_4$ symmetry is broken to $Z_2$, and neutrino masses are generated at one-loops due to the mixings between the neutral components of the inert scalar doublet and the singlet scalar field $S$. There is a dark matter candidate from the lightest neutral scalar field, which is a mixture of the inert scalar doublet and the singlet scalar field $S$, in general. The $Z_4$ breaking mass terms are constrained by electroweak precision data and direct detection (DD) bounds for dark matter, favoring small mixings or almost degenerate masses for the DM scalars. As a result, we discuss the implications of the results for small neutrino masses and DD-safe dark matter.

   hep-phJHEP(2025)·3 citations
5. 05*

   Axion searches at colliders

   Michele Tammaro🇮🇹 · Jure Zupan🇺🇸

   We provide an introduction to searches for axions and Axion-Like Particles (ALPs) at colliders. After covering the basics of collider physics, with a focus on production and detection of new particles, we give a rather broad introduction into searches for dark sectors at colliders. While our focus is on searches for light dark sectors, with the special emphasis on ALPs, we also contrast these with searches for heavy dark matter. In the final part of the notes we provide a ``tutorial'', a worked out example of a search for a photo-philic ALP in $e^{+}{e}^{-}$ collisions, reflecting the actual analysis that was performed at Belle-II with early data.

   hep-ph4 citations
6. 06*

   Post-hoc reweighting of hadron production in the Lund string model

   Benoît Assi🇺🇸 · Christan Bierlich🇸🇪 · Philip Ilten🇺🇸 · Tony Menzo🇺🇸 · Stephen Mrenna🇺🇸 · Manuel Szewc🇺🇸 · Michael K. Wilkinson🇺🇸 · Ahmed Youssef🇺🇸 · Jure Zupan🇺🇸

   We present a method for reweighting flavor selection in the Lund string fragmentation model. This is the process of calculating and applying event weights enabling fast and exact variation of hadronization parameters on pre-generated event samples. The procedure is post hoc, requiring only a small amount of additional information stored per event, and allowing for efficient estimation of hadronization uncertainties without repeated simulation. Weight expressions are derived from the hadronization algorithm itself, and validated against direct simulation for a wide range of observables and parameter shifts. The hadronization algorithm can be viewed as a hierarchical Markov process with stochastic rejections, a structure common to many complex simulations outside of high-energy physics. This perspective makes the method modular, extensible, and potentially transferable to other domains. We demonstrate the approach in Pythia, including both numerical stability and timing benefits.

   hep-phSciPost Phys.(2025)·9 citations
7. 07*

   Electroweak Observables in Neutrino-Electron Scattering from a Muon Storage Ring

   André de Gouvêa🇺🇸 · Adrian Thompson🇺🇸

   We investigate the sensitivity of a companion neutrino detector situated in the plane of a high-energy, high-intensity muon storage ring to elastic ${\nu }_{\mu }$ and ${\nu }_e$ scattering on electrons (E$\nu$ES). Assuming a muon collider with center-of-mass energies of up to 10~TeV, we report sensitivity to the weak couplings $g_V$ and $g_A$ up to around 0.05% relative error, and sensitivity to the weak mixing angle in the momentum transfer $Q\in [10^{-2},2]$~GeV range up to around 0.03% relative error. E$\nu$ES measurements with high-energy muon storage rings allow one to directly interrogate the momentum-transfer regime associated with the NuTeV anomaly. This level of precision allows unique sensitivity to the momentum-dependence of ${\sin }^2{\theta }_W$. We estimate that with the neutrinos from a $E_{\mu }=1.5$~TeV (or higher) muon collider, the hypothesis that ${\sin }^2{\theta }_W$ does not ``run'' can be safely ruled out.

   hep-phhep-exJHEP(2025)·9 citations
8. 08*

   Probing ALP-portal fermionic dark matter at the $e^{+}{e}^{-}$ colliders

   Subhaditya Bhattacharya🇮🇳 · Sahabub Jahedi🇨🇳 · Soumen Kumar Manna🇮🇳 · Arunansu Sil🇮🇳

   Axion-like particles (ALPs) are promising candidates for mediating interactions between a dark sector and the Standard Model (SM). In this work, considering the effective interactions of ALPs with the SM gauge bosons and a fermion dark matter (DM), we explore the DM relic satisfied parameter space and assess its testability through indirect searches. The effect of early kinetic decoupling is also discussed in the resonant regime. The potential of probing such ALP-portal fermionic DM at the electron-positron colliders is investigated with the mono-photon plus missing energy final states. We show that a spectacular distinction between the signal and SM background is possible via the missing energy variable, the seed of which lies in the ALP-photon interaction, which also governs the relic density of DM. We further discuss the sensitivity of ALP-photon coupling using the ${\chi }^2$ analysis at the future electron-positron collider specifications.

   hep-phPRD(2026)·6 citations
9. 09*

   Hadron multiplicity fluctuations in perturbative QCD

   Yu.L. Dokshitzer🇱🇻 · B.R. Webber🇬🇧

   We examine hadron multiplicity fluctuations in hard processes and confront analytic QCD predictions with the pattern of multiplicity fluctuations observed in $e^{+}{e}^{-}$ annihilation and high-$p_t$ jets produced in $pp$ collisions at the LHC. Special emphasis is placed on high-multiplicity fluctuations in jets. Selecting events with hadronic multiplicity exceeding the average value by a factor of 3 or more in various processes has been a source of conundrums for many years. We discuss two recent high-multiplicity puzzles and attempt to reveal their common origin.

   hep-phJHEP(2025)·13 citations
10. 10*

    What is the Hierarchy Problem?

    Michael E. Peskin🇺🇸

    Is there a Hierarchy Problem? If so, what, exactly, is the problem? Almost every theorist has a personal answer to these questions. In this article, I give my answers. I will explain that the Hierarchy Problem is not a formal problem but rather our ignorance of a crucial physics explanation -- the explanation of the nature of the Higgs boson. Without the solution to this problem, we cannot make progress on the major questions of our field.

    hep-phhep-thNPB(2025)·37 citations
11. 11*

    Brief overview of Candidate de Sitter Vacua

    Andreas Schachner🇩🇪

    We review compactifications of type IIB string theory which produce de Sitter vacua to leading order in the ${\alpha }^{\prime }$ and $g_s$ expansions in line with the scenario proposed by Kachru, Kallosh, Linde, and Trivedi. We detail specific Calabi-Yau orientifold compactifications incorporating the non-perturbative superpotential from Euclidean D3-branes, the full flux-induced superpotential, and the Kähler potential evaluated at string tree level but retaining all orders in ${\alpha }^{\prime }$. Each model hosts a Klebanov-Strassler throat featuring a single anti-D3-brane. The energy associated with this supersymmetry-breaking source, computed at leading order in ${\alpha }^{\prime }$, lifts the minimum to a metastable de Sitter vacuum with all moduli stabilised. A key open challenge is the identification of vacua that remain stable when including additional corrections; an endeavour for which this study provides a solid foundation. This work is a contribution to the proceedings of the Corfu Summer Institute 2024 "School and Workshops on Elementary Particle Physics and Gravity" (CORFU2024) and is based on arXiv:2406.13751.

    ↳ hep-thhep-phPoS(2025)·4 citations
12. 12*

    Bayesian Inference of Hybrid Star Properties from Future High-Precision Measurements of Their Radii

    Bao-An Li🇺🇸 · Xavier Grundler🇺🇸 · Wen-Jie Xie🇨🇳 · Nai-Bo Zhang🇨🇳

    Future high-precision X-ray and gravitational-wave observations of neutron stars (NSs) are expected to constrain NS radii with uncertainties as small as $\sigma \simeq 0.1$~km. Such unprecedented precision offers a unique opportunity to extract new information about the nature and equation of state (EOS) of supradense matter in NS cores. Using mock radius data with uncertainties ranging from $\sigma =1.0$ to $0.1$~km, together with a flexible meta-model NS EOS that allows for a first-order hadron-quark phase transition, we perform a Bayesian statistical analysis to assess the impact of radius measurements on EOS constraints. We find that high-precision radius measurements, particularly for massive NSs, significantly tighten constraints on the hadron-quark transition density ${\rho }_t$, the quark matter mass fraction in NS cores, and several parameters characterizing the EOS of supranuclear hadronic matter, although the degree of improvement depends on the assumed prior range of ${\rho }_t$. In contrast, even with the highest precision considered, NS radii -- including those of massive stars -- remain largely insensitive to the stiffness of quark matter, independent of the measurement accuracy or the prior range adopted for ${\rho }_t$.

    ↳ astro-ph.HEastro-ph.GAhep-phnucl-ex+1ApJ(2026)·16 citations
13. 13*

    Interactions of the scalaron dark matter in $f(R)$ gravity

    Yuri Shtanov🇺🇦 · Yurii Sheiko🇺🇦

    In $f(R)$ gravity, the scalaron -- a scalar degree of freedom arising from modification of General Relativity -- could account for all dark matter in the universe if its mass lies in the meV--MeV range. In this work, we revisit the scalaron's interactions with Standard Model particles, assuming their minimal coupling to gravity. In particular, we provide a detailed calculation of the scalaron's decay rate into two photons -- a one-loop process of significant interest that has been the subject of discrepancies in the literature. We demonstrate that a direct evaluation of loop diagrams with appropriate regularisation eliminates the ambiguities inherent in methods relying on Jacobians from field redefinitions. Assuming the scalaron constitutes all of dark matter, we calculate the average cosmological background radiation produced by its decays into photons. We also estimate the contribution of primordial scalarons emitted in the hot early universe to the present dark matter density and find it to be negligible. Our results support all key aspects of the original scenario, in which scalaron dark matter behaves as a coherently oscillating field.

    ↳ astro-ph.COgr-qchep-phJCAP(2025)·4 citations
14. 14*

    Dark matter and modified gravity: Einstein clusters from a non-minimally coupled vector field

    Pedro G. S. Fernandes🇩🇪 · Vitor Cardoso🇩🇰

    We show that a vector field non-minimally coupled to gravity reproduces exactly the dynamics of an Einstein cluster -- a large ensemble of non-interacting particles moving on circular geodesics under their collective gravitational field. Since Einstein clusters are known to be able to account for flat galactic rotation curves, our results suggest that such rotation curves may arise as a manifestation of modified gravity.

    ↳ gr-qcastro-ph.COhep-ph10 citations
15. 15*

    Gluon Parts of Gravitational Form Factors and Mass Distribution

    Peter C. Tandy🇺🇸

    The parton structure of the nucleon and pion is investigated in an exploratory model that allows one to assess whether the dressing of quarks can, by itself, produce realistic gluon contributions to light-cone momentum fractions, gravitational form factors, mass/energy distributions and their radii. The model is the Dyson-Schwinger Equations in Rainbow-Ladder truncation. For the parton mass/energy distributions as a function of momentum transfer, we directly calculate matrix elements of the Energy-Momentum Tensor by utilizing its similarity to the momentum fraction moment of GPDs associated with deep inelastic scattering. A variety of gravitational form factors are obtained including the D-term.

    ↳ nucl-thhep-phhep-thPoS(2025)·3 citations
16. 16*

    JFlow: Model-Independent Spherical Jeans Analysis using Equivariant Continuous Normalizing Flows

    Sung Hak Lim🇰🇷 · Kohei Hayashi · Shun'ichi Horigome · Shigeki Matsumoto🇯🇵 · Mihoko M. Nojiri🇯🇵

    The kinematics of stars in dwarf spheroidal galaxies have been studied to understand the structure of dark matter halos. However, the kinematic information of these stars is often limited to celestial positions and line-of-sight velocities, making full phase space analysis challenging. Conventional methods rely on projected analytic phase space density models with several parameters and infer dark matter halo structures by solving the spherical Jeans equation. In this paper, we introduce an unsupervised machine learning method for solving the spherical Jeans equation in a model-independent way as a first step toward model-independent analysis of dwarf spheroidal galaxies. Using equivariant continuous normalizing flows, we demonstrate that spherically symmetric stellar phase space densities and velocity dispersions can be estimated without model assumptions. As a proof of concept, we apply our method to Gaia challenge datasets for spherical models and measure dark matter mass densities for given velocity anisotropy profiles. Our method can identify halo structures accurately, even with a small number of tracer stars.

    ↳ astro-ph.GAastro-ph.COcs.LGhep-ex+12 citations

* 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.