Fri·Aug 23, 2024Friday·August 23, 2024

1. 01*

   $\varphi$-$p$ bound state and completeness of quantum states

   Arkadiusz Kuros🇵🇱 · Radoslaw Maj🇵🇱 · Stanislaw Mrowczynski🇵🇱

   The existence of a bound state of a $\varphi$ meson and proton has been recently indicated on the basis of a combined analysis of the measured $\varphi$-$p$ correlation function and the QCD lattice calculations of $\varphi$-$p$ interaction in the spin 1/2 and 3/2 channels. We check whether the correlation functions and bound state formation rate satisfy the sum rule which follows from the completeness of quantum states. The sum rule is not satisfied but it is close to it, suggesting that the inferred scattering parameters, which determine the correlation functions, are not fully consistent with the potential responsible for the bound state existence.

   hep-phnucl-th2 citations
2. 02*

   New Limits on Light Dark Matter-Nucleon Scattering

   Peter Cox🇦🇺 · Matthew J. Dolan🇦🇺 · Joshua Wood🇦🇺

   We derive new bounds on hadronically-interacting, sub-GeV mass dark matter. First, we show that one-loop interactions with photons can be sufficient to maintain equilibrium between the dark matter and Standard Model sectors at MeV temperatures, resulting in constraints from Big Bang Nucleosynthesis. Using chiral perturbation theory, we find that this leads to an upper bound on the dark-matter--nucleon scattering cross-section that is orders of magnitude stronger than existing astrophysical constraints. Furthermore, we show that even if these interactions remain out of equilibrium, there is an irreducible freeze-in abundance of dark matter that can easily overclose the universe. We also compute new bounds from rare Kaon decays that can provide even stronger constraints. Our results have significant implications for future direct detection experiments aiming to search for MeV-scale dark matter.

   hep-phPRD(2025)·13 citations
3. 03*

   Three-zero texture of quark-mass matrices as a solution to the strong CP problem

   Qiuyue Liang🇯🇵 · Risshin Okabe🇯🇵 · Tsutomu T. Yanagida🇯🇵

   The strong charge-parity (CP) problem has been a long-standing problem in particle physics since 1976, illustrating the small CP-violation phase in quantum chromodynamics (QCD). The axion, based on the Peccei-Quinn mechanism, is the most popular solution to the problem. In this paper, we propose an alternative solution based on the three-zero texture of quark mass matrices without additional heavy quark states, which has been shown to fit data well. We show that the required three-zero texture is naturally constructed in a six-dimensional spacetime with a ${\mathbf{T}}^2/{\mathbb{Z}}_3$ orbifold compactification.

   hep-phhep-thPLB(2024)·11 citations
4. 04*

   Féeton dark matter above the $e^{-}{e}^{+}$ threshold

   Tatsuya Hayashi🇯🇵 · Shigeki Matsumoto🇯🇵 · Yuki Watanabe🇯🇵 · Tsutomu T. Yanagida🇯🇵

   The new gauge boson introduced in the minimal extension of the standard model (SM) by gauging the U(1)${}_{\mathrm{B}-\mathrm{L}}$ symmetry plays the role of dark matter when the U(1)${}_{\mathrm{B}-\mathrm{L}}$ gauge coupling is highly suppressed. This dark matter, named the Féeton dark matter is known to be efficiently created in the early universe by inflationary fluctuations with minimal gravity coupling, hence the framework, the gauged U(1)${}_{\mathrm{B}-\mathrm{L}}$ extended SM + inflation, solves the four major problems of the SM; neutrino masses/mixings, dark matter, baryon asymmetry of the universe, and the initial condition of the universe (inflation). We comprehensively study the phenomenology of the dark matter when it is heavier than the $e^{-}{e}^{+}$ threshold, namely twice the electron mass, considering the threshold effect on the dark matter decay into $e^{-}{e}^{+}$. The viable parameter region is found only in the threshold region, while the branching fraction of the decay into $e^{-}{e}^{+}$ (i.e., the $e^{-}{e}^{+}$ signal) never vanishes even at the threshold due to the effect. As a result, the pure U(1)${}_{\mathrm{B}-\mathrm{L}}$ extension without the kinetic mixing between the U(1)${}_{\mathrm{B}-\mathrm{L}}$ and hyper-charge gauge bosons have already been excluded by the present observation of the 511\,keV photon from the galactic center. So, the Féeton dark matter requires a non-zero kinetic mixing to be a viable dark matter candidate and will be efficiently explored by future MeV-gamma ray telescopes thanks to the non-vanishing decay process into $e^{-}{e}^{+}$.

   hep-phPRD(2025)·4 citations
5. 05*

   X650 $\to$ ZZ/WW/H125H95/A450Z/$\gamma \gamma$ -- $J=1$, $J=2$, narrow or wide resonance?

   Alain Le Yaouanc🇫🇷 · François Richard🇫🇷

   At ICHEP 2024 CMS has published RUN2 results for ZZ->4 leptons and reached the conclusion that there is no evidence for a scalar resonance H650 decaying into ZZ, as was also concluded by ATLAS using an MVA analysis optimised for a scalar particle. Since this resonance is indicated into ZZ by ATLAS in a Cut Based Analysis and into three other modes: WW and h95h125 by CMS, ttZ by ATLAS , the present paper is an attempt to understand these apparent contradictions. Our conclusion is that strict selections for the reaction H650->ZZ cut as much into the signal than into the background, therefore reducing its statistical significance. A plausible interpretation of this behaviour is that these selections are inadequate for a spin 2 particle produced by the VBF process and decaying into ZZ with an angular distribution similar to the Drell Yan background. If true, our description of the various findings in term of the Georgi Machacek model needs to be deeply revised, which is attempted in the present note. A scenario with T690 as a spin 2 narrow resonance is presented which naturally accommodates WW/ZZ and h95h125 decays, while we suggest that A450Z could come from a H650 nearby resonance. We propose a scheme in which scalar resonances are accommodated in three scalar isodoublets, while T690, T450++, T375+ and T350 belong to two tensor isoquintuplets. In this scenario, T690 could be a narrow resonance which interferes with the SM background, as confirmed by its observation in the two photon mode, reinforcing a Kaluza Klein graviton interpretation. If, as indicated by ATLAS and CMS, T690 couples to e+e-, this scenario leads to a dramatic prediction for future $e^{+}{e}^{-}$ colliders.

   hep-phhep-ex4 citations
6. 06*

   Multiple testing for signal-agnostic searches of new physics with machine learning

   Gaia Grosso🇺🇸 · Marco Letizia🇮🇹

   In this work, we address the question of how to enhance signal-agnostic searches by leveraging multiple testing strategies. Specifically, we consider hypothesis tests relying on machine learning, where model selection can introduce a bias towards specific families of new physics signals. We show that it is beneficial to combine different tests, characterised by distinct choices of hyperparameters, and that performances comparable to the best available test are generally achieved while providing a more uniform response to various types of anomalies. Focusing on the New Physics Learning Machine, a methodology to perform a signal-agnostic likelihood-ratio test, we explore a number of approaches to multiple testing, such as combining p-values and aggregating test statistics.

   hep-phcs.LGhep-exphysics.data-an+1EPJC(2025)·11 citations
7. 07*

   Electroweak $W^{+}{W}^{+}$ production in association with three jets at NLO QCD matched with parton shower

   Barbara Jäger🇩🇪 · Santiago Lopez Portillo Chavez🇩🇪

   We present a next-to-leading order QCD calculation for the electroweak production of a pair of same-sign weak gauge bosons in association with three jets in the region dominated by vector boson scattering, and its matching with parton-shower programs according to the POWHEG formalism. Our calculation allows for an accurate description of jet observables crucial for the optimization of experimental analyses of vector boson scattering processes. We find QCD corrections and parton-shower effects moderate in size for inclusive quantities and distributions of the tagging jets. A larger impact of these corrections is observed for subleading jets.

   hep-phJHEP(2025)·6 citations
8. 08*

   Q-ball collisions and their Gravitational Waves

   Deog Ki Hong🇰🇷 · Stephen J. Lonsdale🇰🇷

   Sydney Coleman's Q-ball remains a compelling instance of localised object formation within classical field theory, independently of the quantum evolution. The theoretical possibility of such objects forming and colliding in the early universe from models such as Affleck-Dine fragmentation, or from a number of mechanisms where they are produced copiously with various size and charges to be dark matter candidates, makes it important to study in detail Q-ball collision phenomenology. In this work we present results from a study of Q-ball collisions and their gravitational waves, using a new general code package for scalar fields coupled to gravity. We then comment on the possibility of future gravitational wave detectors searching for signals of Q-ball collisions.

   hep-phgr-qcPRD(2024)·4 citations
9. 09*

   Color superconductivity and speed of sound in the two-flavor quark-meson diquark model

   Jens O. Andersen🇳🇴 · Mathias P. Nødtvedt🇳🇴

   We discuss the properties of the two-flavor quark-meson diquark (QMD) model as a renormalizable low-energy model for QCD in the 2SC phase of QCD. The effective degrees of freedom are the mesons (sigma and pions), quarks, and diquarks. Some of the parameters of the model can be determined by expressing them in terms of the vacuum meson masses and the pion decay constant using the on-shell renormalization scheme. The remaining parameters are considered free, although they in principle can be calculated from QCD. The thermodynamic potential is calculated in a mean-field approximation taking only quark loops into account. In this approximation, we derive a set of renormalization group equations for the running masses and couplings. The solutions to these equations are used to improve the thermodynamic potential $\Omega$ and thereby thermodynamic quantities. Four parameter sets are chosen and the phase diagram in the $\bar{\mu }$--$T$ plane is obtained (with $\bar{\mu }=\frac{1}{3}{\mu }_B$). We also calculate the speed of sound $c_s$ as a function of $\bar{\mu }$ at vanishing temperature. For large values of $\bar{\mu }$, the speed of sound approaches the conformal limit $c_s=\frac{1}{\sqrt{3}}$ from above, in disagreement with perturbative calculations, but agreement with hard-dense-loop resummed perturbation theory.

   hep-phnucl-thPRD(2025)·18 citations
10. 10*

    From strange-quark tagging to fragmentation tagging with machine learning

    Yevgeny Kats🇮🇱 · Edo Ofir🇮🇱

    We apply advanced machine learning techniques to two challenging jet classification problems at the LHC. The first is strange-quark tagging, in particular distinguishing strange-quark jets from down-quark jets. The second, which we term fragmentation tagging, involves identifying the fragmentation channel of a quark. We exemplify the latter by training neural networks to differentiate between bottom jets containing a bottom baryon and those containing a bottom meson. The common challenge in these two problems is that neither quark lifetimes and masses nor parton showering provide discriminating tools, making it necessary to rely on differences in the distributions of the hadron types contained in each type of jet and their kinematics. For these classification tasks, we employ variations of Graph Attention Networks and the Particle Transformer, which receive jet and all constituent properties as inputs. We compare their performance to a simple Multilayer Perceptron that uses simple variables. We find that the more sophisticated architectures do not improve $s$-quark versus $d$-quark jet differentiation by a significant amount, but they do lead to a significant gain in $b$-baryon versus $b$-meson jet differentiation.

    hep-phhep-exPRD(2025)·5 citations
11. 11*

    Singlet-Doublet Fermionic Dark Matter in Gauge Theory of Baryons

    Taramati🇮🇳 · Rameswar Sahu🇮🇳 · Utkarsh Patel🇮🇳 · Kirtiman Ghosh🇮🇳 · Sudhanwa Patra🇮🇳

    We are considering a minimal $U(1{)}_B$ extension of the Standard Model (SM) by promoting the baryon number as a local gauge symmetry to accommodate a stable dark matter (DM) candidate. The gauge theory of baryons induces non-trivial triangle gauge anomalies, and we provide a simple anomaly-free solution by adding three exotic fermions. A scalar $S$ spontaneously breaks the $U(1{)}_B$ symmetry, leaving behind a discrete $Z_2$ symmetry that ensures the stability of the lightest exotic fermion was originally introduced to cancel the triangle gauge anomalies. Scenarios with weakly interacting DM candidates having non-zero hypercharge usually face stringent constraints from experimental bounds on the DM spin-independent direct-detection (SIDD) cross-section. In this work, we consider a two-component singlet-doublet fermionic dark matter scenario, which significantly relaxes the constraints from bounds on the DM SIDD cross-section for suppressed singlet-doublet mixing. We show that the model offers a viable parameter space for a cosmologically consistent DM candidate that can be probed through direct and indirect searches, collider experiments, and gravitational wave (GW) experiments.

    hep-phJHEP(2025)·7 citations
12. 12*

    Nuclear Production and Analytic Attenuation of Energetic MeV Solar Dark Matter

    Shao-Feng Ge🇨🇳 · Jie Sheng🇨🇳 · Chen Xia🇨🇳 · Chuan-Yang Xing🇨🇳

    We propose a solar production mechanism of MeV dark matter to overcome the energy threshold in direct detection experiments. In particular, the proton and deuteron fussion to ${}^3\mathrm{He}$ of the $pp$ chain that produces energetic neutrino and gamma photon with 5.5MeV of energy release can also produce a pair of dark matter particles. Besides, we establish an analytical formalism of using the Boltzmann equation to study the solar attenuation effect on the produced dark matter flux. The projected sensitivity is illustrated with Argon target at the DarkSide-LowMass experiment.

    hep-phastro-ph.HEhep-exPLB(2026)·7 citations
13. 13*

    Thermal and nonthermal dark matters with gravitational neutrino reheating

    Md Riajul Haque🇮🇳 · Debaprasad Maity🇮🇳 · Rajesh Mondal🇮🇳

    We have discussed in detail how neutrinos produced from inflaton solely through gravitational interaction can successfully reheat the universe. For this, we have introduced the well-known Type-I seesaw neutrino model. Depending on seesaw model parameters, two distinct reheating histories have been realized and dubbed as i) Neutrino dominating: Following the inflaton domination, the universe becomes neutrino dominated, and their subsequent decay concludes the reheating process, and ii) Neutrino heating: Despite being sub-dominant compared to inflaton energy, neutrinos efficiently heat the thermal bath and produce the radiation dominated universe. Imposing baryon asymmetric yield, the $\Delta N_{\mathrm{eff}}$ constraint at Big Bang Nucleosynthesis (BBN) considering primordial gravitational waves (PGW), we have arrived at the following constraints on reheating equation of state to lie within $0.5\lesssim w_{\varphi }\lesssim 1.0$. In these neutrino-driven reheating backgrounds, we further performed a detailed analysis of both thermal and non-thermal production of dark matter (DM), invoking two minimal models, namely the Higgs portal DM and classical QCD pseudo scalar axion. An interesting correlation between seemingly uncorrelated DM and Type-I seesaw parameters has emerged when confronting various direct and indirect observations. When DMs are set to freeze-in, freeze-out, or oscillate during reheating, new parameter spaces open, which could be potentially detectable in future experiments, paving an indirect way to look into the early universe in the laboratory.

    hep-phastro-ph.COgr-qchep-thPRD(2025)·13 citations
14. 14*

    Novel method to indirectly reconstruct neutrinos in collider experiments

    Hongrong Qi🇹🇼 · Paoti Chang🇹🇼

    Neutrinos play a crucial role in particle physics, but cannot be tracked in collider experiments. If more than one neutrino is present in a collision event, it is impossible to extract neutrinos' information using any of the traditional methods. In this Letter, we introduce an innovative inclusive-tagging scheme that is capable of capturing the four-momentum of an undetected particle on the signal side, such as a neutrino, $K_L^0$, etc., in collider experiments. This is the first proposed solution to the longstanding challenge outlined above. Our scheme, based on an asymptotically recursive vector sequence, has the potential to catalyze a significant transformation in the reconstruction techniques for (semi-)leptonic decays of collider experiments. The application and development of this scheme will greatly improve the precision of measurements of Standard Model parameters in the (semi-)leptonic sector with the same data samples, and could play a pivotal role in the search for new physics. Additionally, the asymptotically recursive (vector) sequence introduced in our scheme might also have promising applications in other fields, such as machine learning.

    hep-phhep-ex0 citations
15. 15*

    UV Completion of Neutral Triple Gauge Couplings

    John Ellis🇬🇧 · Hong-Jian He🇨🇳 · Rui-Qing Xiao🇨🇳 · Shi-Ping Zeng🇨🇳 · Jiaming Zheng🇨🇳

    Neutral triple gauge couplings (nTGCs) are manifestation of new physics beyond the Standard Model (SM), as they are absent in the SM and are first generated by dimension-8 operators in the SM Effective Field Theory (SMEFT). We study the UV completion of nTGCs in a renormalizable model with vector-like heavy fermions. We compute the one-loop heavy fermion contributions to nTGC vertices by matching them to dimension-8 operators in the low energy limit. Such fermion loops contain either heavy fermions only or mixture of heavy fermions with light SM fermions. We find that their contributions can induce dimension-8 nTGC effective operators containing two SM Higgs-doublet fields, which are formulated with a complete set of 7 dimension-8 operators generating off-shell CP-even nTGCs. We present the results in terms of SMEFT coefficients and in terms of nTGC vertices (form factors) with two on-shell gauge bosons. In the heavy-light mixing case there appear terms that cannot be accommodated by conventional parametrizations of form factors due to extra logarithmic corrections. We further discuss the implications for probing such UV dynamics via nTGCs at the high energy colliders.

    hep-phhep-exhep-thPRD(2025)·14 citations
16. 16*

    Interplay between the weak-coupling results and the lattice data in dense QCD

    Yuki Fujimoto🇺🇸

    We discuss the interplay between two first-principles calculations of QCD at high density: perturbative results in the weak-coupling regime and the recent lattice-QCD result at finite isospin density. By comparing these two results, we verify empirically that the weak-coupling calculations of the bulk thermodynamics and the gap parameter for Cooper pairing between quarks can be applicable down to the quark chemical potential $\mu \sim 1$ GeV. Having verified the validity of the weak-coupling results in QCD at finite isospin density, we discuss possible effects on QCD at finite baryon density, which is relevant for the application to realistic environments such as neutron stars, by using the fact that QCD at finite baryon and isospin density have the common weak-coupling expansions. First, we show the size of the color-superconducting gap at finite baryon density is as small as a few MeV at $\mu =1$ GeV, which implies that the color-flavor locked phase may be unstable against unpairing up to $\mu \sim 1.4$ GeV even in the weak-coupling regime. We also introduce a prescription to reduce the ambiguity arising from the undetermined renormalization scale in the weak-coupling calculation by matching with the lattice-QCD data. We demonstrate the effect of such reduction on neutron-star phenomenology by performing the Bayesian analysis.

    hep-phastro-ph.HEhep-latnucl-th15 citations
17. 17*

    Spectral eigenfunction decomposition of a Fokker-Planck operator for relativistic heavy-ion collisions

    A. Rizzi🇩🇪 · G. Wolschin🇩🇪

    A spectral solution method is proposed to solve a previuously developed non-equilibrium statistical model describing partial thermalization of produced charged hadrons in relativistic heavy-ion collisions, thus improving the accuracy of the numerical solution. The particle's phase-space trajectories are treated as drift-diffusion stochastic process, leading to a Fokker-Planck equation (FPE) for the single-particle probability distribution function. The drift and diffusion coefficients are derived from the expected asymptotic states via appropriate fluctuation-dissipation relations, and the resulting FPE is then solved numerically using a spectral eigenfunction decomposition. The calculated time-dependent particle distributions are compared to Pb-Pb data from the ATLAS and ALICE collaborations at the Large Hadron Collider.

    hep-phnucl-thEPJA(2024)·0 citations
18. 18*

    Testing the lepton content of the proton at HERA and EIC

    Leandro Da Rold🇦🇷 · Anibal D. Medina🇦🇷 · Subhojit Roy🇺🇸 · Carlos E.M. Wagner🇺🇸

    Although protons are baryons with an overall vanishing lepton number, they possess a non-trivial leptonic content arising from quantum fluctuations which can be described by lepton parton distribution functions (PDFs) of the proton. These PDFs have been recently computed and can be used to define lepton-induced processes at high-energy colliders. In this article, we propose a novel way to test the computation of lepton PDFs of the proton by analyzing both non-resonant di-lepton and resonant Z gauge boson production processes induced by leptons within the proton at proton-electron colliders like HERA and EIC. Despite the fact that lepton PDFs of the proton are known to be small, this work demonstrates that both processes imply a measurable yield of events at HERA and EIC, which could be used to test these PDFs.

    hep-phhep-exJHEP(2025)·4 citations
19. 19*

    Heavy-quark diffusion in 2+1D and Glasma-like plasmas: evidence of a transport peak

    Liane Backfried🇦🇹 · Kirill Boguslavski🇦🇹 · Paul Hotzy🇦🇹

    We examine how plasma excitations affect the heavy-quark diffusion coefficient in 2+1 dimensional and Glasma-like plasmas, akin to the pre-equilibrium matter describing relativistic heavy-ion collisions at early times. We find that the transport coefficient $2\kappa$ transverse to and ${\kappa }_z$ along the beam direction display a qualitatively different evolution. We attribute this to the underlying excitation spectra of these systems, thus providing evidence for the existence of non-perturbative properties in the spectrum. This is accomplished by first reconstructing the diffusion coefficients using gauge-fixed correlation functions, which accurately reproduces the time evolution of $2\kappa$ and ${\kappa }_z$. We then modify these excitation spectra to study the impact of their non-perturbative features on the transport coefficients. In particular, we find evidence for a novel transport peak in the low-frequency spectrum that is crucial for heavy-quark diffusion. We also demonstrate that gluonic excitations are broad while scalar excitations associated with ${\kappa }_z$ are narrow and strongly enhanced at low momenta. Our findings indicate that the large values and dynamical properties of transport coefficients in the Glasma could originate from genuinely non-perturbative features in the spectrum.

    hep-phhep-latnucl-thPRD(2024)·9 citations
20. 20*

    The Standard Model CP Violation is Enough

    Gilly Elor🇺🇸 · Rachel Houtz🇺🇸 · Seyda Ipek🇨🇦 · Martha Ulloa🇺🇸

    Is the Standard Model Charge-Parity (CP) violation ever enough to generate the observed baryon asymmetry? Yes! We introduce a mechanism of baryogenesis (and dark matter production) that can generate the entire observed baryon asymmetry of the Universe using $\text{only}$ the CP violation within Standard Model systems -- a fête which no other mechanism currently proposed can achieve. Baryogenesis proceeds through a Mesogenesis scenario but with well motivated additional dark sector dynamics: a $\text{morphon}$ field generates present day mass contributions for the particle mediating the decay responsible for baryogenesis. The effect is an enhancement of baryon production whilst evading present day collider constraints. The CP violation comes entirely from Standard Model contributions to neutral meson systems. Meanwhile, the dark dynamics generate gravitational waves that may be searched for with current and upcoming Pulsar Timing Arrays, as we demonstrate with an example. This mechanism, $\text{Mesogenesis with a Morphing Mediator}$, motivates probing a new parameter space as well as improving the sensitivity of existing Mesogenesis searches at hadron and electron colliders.

    hep-phhep-exPRD(2025)·16 citations
21. 21*

    Unitarity, Causality, and Solar System Bounds May Significantly Limit the Use of Gravitational Waves to Test General Relativity

    Alexander Cassem🇺🇸 · Mark P. Hertzberg🇺🇸

    The prospect of detecting/constraining deviations from general relativity by studying gravitational waves (GWs) from merging black holes has been one of the primary motivations of GW interferometers like LIGO/Virgo. Within pure gravity, the only possible way deviations can arise is from the existence of higher order derivative corrections, namely higher powers of the Riemann curvature tensor, in the effective action. Any observational bounds imply constraints on the corresponding Wilson coefficients. At the level of the action, one can imagine the coefficients are sufficiently large so as to be in principle detectable. However, from the point of view of some fundamental principles, namely causality and unitarity, this is much less clear, as we examine here. We begin by reviewing certain known bounds on these coefficients, which together imply a low cut off on the effective theory. We then consider a possible mechanism to generate such terms, namely in the form of many scalars, minimally coupled to only gravity, that can be integrated out to give these higher order operators. We show that a by product of this is the generation of quantum corrections to Newton's potential, whose observable consequences are already ruled out by solar system tests. We point out that over 7 orders of magnitude of improvement in interferometer sensitivity would be required to avoid such solar system constraints. We also mention further constraints from Hawking radiation from black holes.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2025)·4 citations
22. 22*

    Interacting dark sector from Horndeski theories and beyond: Mapping fields and fluids

    Pulkit Bansal (IIT Bombay)🇮🇳 · Joseph P Johnson (IISER Mohali)🇮🇳 · S. Shankaranarayanan (IIT Bombay)🇮🇳

    In Cosmology, when dissipative effects are minimal, the energy content of the Universe can be effectively described as a sum of perfect fluids. Perfect fluid descriptions ensure thermal equilibrium since they equilibrate immediately. However, interactions among different energy content of the Universe might prevent such rapid equilibration. This limitation calls for a more fundamental framework that incorporates these interactions directly at the level of the action. In earlier work, two of the authors demonstrated that an interacting dark energy (DE)-dark matter (DM) field theory action could be derived from a modified gravity action via a conformal transformation, establishing a one-to-one correspondence between the field theory action and fluid for a unique interaction term [arXiv:2006.04618]. In this work, we extend that analysis by considering quadratic order Horndeski gravity, identifying two classes of models: field coupling and field-kinetic coupling. Our approach generalizes the coupling function for DE-DM interactions by incorporating an additional dependence on kinetic terms. We establish a field-to-fluid mapping for dark matter and find that this mapping only holds for a specific form of the interaction strength. Interestingly, we show that this interaction strength excludes non-gravitational interactions between dark energy and dark radiation. Numerical analysis reveals that purely kinetic interactions within the dark sector can significantly alter cosmological evolution compared to non-interacting scenarios, highlighting the strong dependence of cosmological dynamics on coupling strength. A preliminary examination of linear scalar perturbations indicates that the field-kinetic coupling results in a non-zero gravitational slip parameter and momentum exchange.

    ↳ astro-ph.COgr-qchep-phPRD(2025)·11 citations
23. 23*

    Reconstructing the Inflaton Potential: Primordial Black Holes and Gravitational Waves in Slow Roll and Ultra Slow Roll Single Field Inflation

    Gabriele Autieri🇮🇹 · Michele Redi🇮🇹

    We present new single field inflationary scenarios that produce the critical abundance of primordial black holes as dark matter reconstructing the inflaton potential from an input power spectrum. The method is exact in the slow roll approximation but remains effective even when the slow roll conditions are temporarily violated such as in ultra slow roll models. With this method we construct new ultra slow roll scenarios and also models that reproduce the DM abundance within the slow roll regime. As a second application we consider a scalar power spectrum that generates a secondary gravitational wave background compatible with the one recently observed in Pulsar Timing Arrays experiments. These scenarios could be tested by future observations of $\mu -$distortions of the CMB.

    ↳ astro-ph.COhep-phJCAP(2025)·3 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.