Fri·Jan 9, 2026Friday·January 9, 2026

1. 01*

   Unified analysis of screening masses for vector and axial-vector mesons and their diquark partners in the Contact Interaction model

   L. X. Gutiérrez-Guerrero🇲🇽 · M. A. Ramírez-Garrido🇲🇽 · M. A. Pérez de León🇲🇽 · R. J. Hernández-Pinto🇲🇽

   We present a comprehensive study of the screening masses of vector and axial-vector mesons and their corresponding diquark partners within a symmetry-preserving vector-vector contact interaction approach. Our analysis includes mesons and diquarks composed of both light and heavy quarks, providing a unified description of their thermal behavior. The longitudinal and transverse modes of the screening masses are analyzed, and the results are systematically compared with other theoretical approaches. At $T=0$ MeV, our predictions agree with available experimental data, and a comparison with the expected free theory limit at high temperatures is also presented. Notably, the parity partners of the lightest mesons and diquarks converge at high temperatures, signaling chiral symmetry restoration within this framework. These results provide a consistent and detailed picture of meson and diquark properties at finite temperature and lay the groundwork for extending the capabilities of the model to baryon screening masses in the quark-diquark picture.

   hep-phPRD(2026)·1 citation
2. 02*

   $S_4^{\prime }$ Quark Flavour Model in the Vicinity of the Fixed Point $\tau =i\infty$

   S. T. Petcov🇮🇹 · M. Tanimoto🇯🇵

   We study in the bottom-up framework the possibility to generate the quark mass hierarchies without fine-tuning, the quark mixing and CP-violation (CPV) in a flavour model with $S_4^{\prime }$ modular symmetry having minimal number of parameters. The model is considered in the vicinity of the fixed point ${\tau }_{\text{T}}=i\infty$, ${\tau }_{\text{vev}}\sim {\tau }_{\text{T}}$, ${\tau }_{\text{vev}}$ being the vacuum expectation value (VEV) of the modulus $\tau$, which allows to explain the hierarchies of the quark masses. The ten quark observables are described by nine real parameters. The CP-symmetry is broken explicitly since, as is well known, reproducing the observed CPV in the quark sector in the case of spontaneous breaking of CP-symmetry by ${\tau }_{\text{vev}}$ is highly problematic in the class of minimal modular quark flavour models (explaining the quark mass hierarchies without fine-tuning) of the type we consider. We perform a statistical analysis of the model and show that it is phenomenologically viable and consistent, in particular, with the ``inclusive'' decay data on the $|V_{ub}|$ and $|V_{cb}|$ elements of the CKM matrix and, in the case of a very high scale of supersymmetry breaking, with the current ``average'' experimental values of $|V_{ub}|$ and $|V_{cb}|$.

   hep-phhep-thEPJC(2026)·5 citations
3. 03*

   Search for Ultralight Axion Dark Matter with a Levitated Ferromagnetic Torsional Oscillator

   Chunlong Li🇨🇳 · Yiwei Huang🇨🇳 · Shien Yang🇨🇳 · Yichong Ren🇨🇳 · Yu Zhang🇨🇳 · Peiran Yin🇨🇳 · Pu Huang🇨🇳 · Fei Xue🇨🇳

   We present a search for ultralight axion dark matter coupled to electron spins using a levitated ferromagnetic torsional oscillator (FMTO). This platform directly measures axion-induced torques on a macroscopic spin-polarized body, combining large spin density with strong mechanical isolation to probe magnetic fluctuations below 10 Hz while suppressing gradient-field noise. In a first implementation, the experiment yielded 18000 s of analyzable data at room temperature under high vacuum with optical readout and triple-layer magnetic shielding. A likelihood-based statistical framework, incorporating stochastic fluctuations in the axion-field amplitude, was used to evaluate the data. No excess consistent with an axion-induced pseudo-magnetic field was observed near 2e-14 eV. To account for possible shielding-induced signal attenuation, we quantify its effect and report both the uncorrected (g_aee < 1e-7) and attenuation-corrected (g_aee < 6e-5) 90% CL limits on the axion-electron coupling. Looking ahead, improvements guided by both noise-budget analysis and shielding-attenuation considerations, including optimized levitation geometry, cryogenic operation, and superconducting shielding, are expected to boost sensitivity by multiple orders of magnitude.

   hep-phastro-ph.COhep-ex4 citations
4. 04*

   CP, or not CP, that is the question...

   Andreas Ringwald🇩🇪

   Motivated by recent claims questioning the existence of strong CP violation, we present a pedagogical review of CP violation in Quantum Chromodynamics (QCD). Using fundamental properties of the QCD partition function, we analyze the dependence of the chiral quark and CP violating gluon condensates on the theta parameter and the quark masses in the chiral limit. We show explicitly how CP violation arises, clarify the role of the axial U(1) anomaly and the ordering of the infinite-volume limit, and discuss the conditions under which CP symmetry may or may not be realized, including in the large-N framework. Our results reaffirm the presence of strong CP violation for physically relevant parameters and thus the theoretical basis of the strong CP problem and axion physics.

   hep-phPoS(2026)·9 citations
5. 05*

   Dark NSI & neutrino oscillations : probing via ${\delta }_{CP}$ measurements at DUNE and T2HK

   Dharitree Bezboruah🇮🇳 · Abinash Medhi🇮🇳 · Moon Moon Devi🇮🇳

   We investigate the possibility of neutrinos interacting with a scalar dark matter field and the resulting implications for neutrino oscillations in the long-baseline sector. As our Universe is predominantly composed of dark matter, neutrinos propagating over astrophysical and terrestrial baselines inevitably traverse a dark matter background. The coherent forward scattering of neutrinos in such a background induces a medium-dependent correction to the mass-squared term in the effective neutrino Hamiltonian having opposing signs for neutrinos and antineutrinos. We study how the elements of this correction matrix, arising from coherent forward scattering of neutrinos with scalar dark matter background referred to as dark non-standard interactions (dark NSI), modify neutrino oscillation probabilities. Furthermore, we also study the effect of the off-diagonal elements and the associated phases on the measurement of leptonic CP violating phase focusing on the upcoming long-baseline superbeam experiments DUNE and T2HK. We show that dark NSI can lead to substantial enhancement or suppression of CP-violation sensitivity, depending on the true values of the dark NSI phases ${\varphi }_{\alpha \beta }$. We further explored how the synergy of DUNE and T2HK can effectively mitigate the degeneracies due to the dark NSI phases, and can restore or even enhance the CP sensitivity as compared to the standard oscillation scenario.

   hep-ph0 citations
6. 06*

   Braneworld Baryogenesis and QCD-Era Magnetogenesis: A Predictive Link

   Michaël Sarrazin🇫🇷

   We demonstrate that primordial magnetic fields (PMF) play a decisive role in the braneworld baryogenesis scenario of [Phys. Rev. D $\text{110}$, 023520 (2024)], where C/CP violation arises from the coupling of visible and hidden matter-antimatter sectors through a pseudo-scalar field. Although this mechanism generates baryon number efficiently only after the quark-hadron transition, by incorporating a realistic stochastic PMF within a semi-analytical framework, we find that matching the observed baryon-antibaryon asymmetry robustly requires PMF strengths of order $10^{10}$ T right after the transition, in agreement with causal QCD-era magnetogenesis. We further reveal that magnetic fluctuations drive the baryon-density spectrum to white noise on large scales, yielding an isocurvature component compatible with Cosmic Microwave Background (CMB) bounds. This establishes a predictive link between the braneworld baryogenesis model and realistic early-Universe magnetic fields.

   hep-phastro-ph.COEPJC(2026)·0 citations
7. 07*

   NLO QCD sum rules analysis of $1^{-+}$ tetraquark states

   Wei-Yang Lai🇨🇳 · Hong-Ying Jin🇨🇳

   We present a next-to-leading order QCD sum rule analysis of $J^{PC}=1^{-+}$ light tetraquark states. By investigating various compact tetraquark and molecular configurations, we determine the mass spectrum of these states. Our calculations exclude the possibility that ${\pi }_1(1400)$ is a tetraquark or hybrid-tetraquark mixture. This suggests that it may not exist, which is consistent with recent experimental results. In contrast, we obtained multiple $1^{-+}$ states around $2.0\text{GeV}$ that match well with ${\pi }_1(2015)$, which makes us confident that ${\pi }_1(2015)$ is a tetraquark candidate. As for ${\pi }_1(1600)$, our results indicate that the tetraquark currents tend to couple to heavier states, reducing the possibility of it being a tetraquark, while earlier studies suggested the opposite.

   hep-phCPC(2026)·0 citations
8. 08*

   ALP and $Z^{\prime }$ boson at the Electron-Ion collider

   Amit Adhikary🇫🇷 · Dilip Kumar Ghosh🇮🇳 · Sk Jeesun🇨🇳 · Sourov Roy🇮🇳

   We study the sensitivity of the upcoming electron-ion (EIC) collider to purely electrophilic new physics in the GeV mass range. Within an effective field theory framework, we consider two different scenarios: an axion-like particle (ALP) and a new heavy neutral vector gauge boson $Z^{\prime }$, each couples to electrons only. We analyze electron-proton collisions at $\sqrt{s}=141$ GeV with an integrated luminosity of $100{\mathrm{fb}}^{-1}$, focusing primarily on the tri-electron final state. Additionally, loop-induced ALP-photon couplings driven photon final states are also explored. Incorporating realistic detector effects and systematic uncertainties, we obtain projected exclusion limits on the relevant cross-sections and couplings. We find that the results from EIC can significantly extend the sensitivity to electrophilic axion-like particles and $Z^{\prime }$ bosons in regions of parameter space that remain weakly constrained by existing experiments.

   hep-phhep-exPRD(2026)·4 citations
9. 09*

   Effective Range Expansion with the Left-Hand Cut: Higher Order Improvements

   Wen-Jia Wang🇨🇳 · Bing Wu🇨🇳 · Meng-Lin Du🇨🇳 · Feng-Kun Guo🇨🇳

   A model-independent parameterization of the low-energy scattering amplitude that incorporates the left-hand cut from one-particle exchange, an extension of the conventional effective-range expansion (ERE), was recently proposed and successfully applied to the low-energy $D{D}^{\ast }$ system [Phys. Rev. Lett. 135, 011903 (2025)]. While the original formulation is based on a nonrelativistic approximation and is thus limited to a [1,1] approximant for self-consistency, we extend the framework by explicitly including the higher-order terms up to $\mathcal{O}(k^6)$. We systematically investigate the reliability and robustness of the generalized ERE by incorporating relativistic kinematic effects. In addition, we develop a relativistic version of the ERE that accounts for lhc contributions. These results affirm the generalized ERE as a robust and systematically improvable framework for near-threshold scattering processes, providing both analytical and numerical reliability for applications in two-body scattering problems with a particle exchange.

   hep-phnucl-thPRD(2026)·2 citations
10. 10*

    Axion superradiance

    Francesca Chadha-Day🇬🇧

    Light bosonic fields may suffer an instability around a rotating compact object. This process, known as superradiance, leads to the exponential amplification of the field around a black hole or neutron star, while the spin of the central object is correspondingly depleted. The discovery of a highly spinning black hole could therefore be used to constrain the existence of light bosons such as axions in a particular range of masses. These constraints apply for very low non-gravitational couplings between the boson and the Standard Model, offering a powerful search strategy for new physics. However, care must be taken to include the more complex effects of the black hole's astrophysical environment. Conversely, stellar superradiance could allow us to probe additional non-gravitational interactions between a new boson at the stellar matter. In this article, I will discuss the current status and future directions of axion superradiance. This is a contribution to the proceedings of the 3rd General Meeting of the COST Action COSMIC WISPers.

    hep-phPoS(2026)·0 citations
11. 11*

    Full off-shell $t\bar{t}$ production in the semileptonic channel at the LHC

    Leon Mans🇩🇪

    In this contribution, we summarize our results on the complete NLO predictions for the production of off-shell top quark pairs in the $\ell +j$ channel at the LHC. All NLO QCD and electroweak corrections are consistently included across the full set of LO contributions and partonic subprocesses, while retaining finite-width effects of the top quarks and the electroweak gauge bosons. Resonant and non-resonant contributions as well as interference effects are included in the complete calculation. We pay special attention to infrared singularities associated with photons and jets appearing simultaneously in the final state. Fiducial integrated and differential cross-section results are presented for $pp$ collisions at $\sqrt{s}=13.6$ TeV.

    hep-phJ.Subatomic Part.Cosmol.(2026)·0 citations
12. 12*

    Non-Thermal Leptogenesis in the BLSM with Inverse Seesaw Mechanism

    David Delepine🇲🇽 · Shaaban Khalil🇪🇬

    We investigate the viability of non-thermal leptogenesis in the gauged $U(1{)}_{B-L}$ extension of the Standard Model (BLSM) with an inverse seesaw (ISS) mechanism for neutrino mass generation. In this framework, right-handed neutrinos typically have $\mathcal{O}(1)$ Yukawa couplings, which induce strong washout effects and render conventional thermal leptogenesis ineffective. We demonstrate that a successful baryogenesis scenario can nevertheless be realized through non-thermal leptogenesis, where right-handed neutrinos are produced from the decay of the heavy $B-L$ Higgs boson $\chi$. We explicitly analyze the interplay between the dilution factor $T_R/M_{\chi }$ and the washout parameter characteristic of the ISS, highlighting the tension between suppressing washout effects and maintaining sufficient reheating. We show that a viable lepton asymmetry can be generated provided the scalar mass spectrum is appropriately tuned --- a condition that requires a fine-tuning of order one part in $10^5$ against one-loop radiative corrections --- allowing for a reduced reheating temperature while keeping washout under control. The resulting lepton asymmetry is efficiently converted into the observed baryon asymmetry of the Universe via sphaleron processes. Our results establish that the inverse-seesaw $B-L$ model remains a predictive and robust framework for non-thermal leptogenesis and baryogenesis.

    hep-phhep-thPRD(2026)·2 citations
13. 13*

    Response to 2512.23460[hep-ph] by Czarnecki and Khanna ("False vacuum decay and flaws in Frampton's model for the origin of life")

    P.H. Frampton🇮🇹

    We respond to a critique 2512.23460[hep-ph] of our paper 2505.05634[hep-ph]

    hep-ph0 citations
14. 14*

    Dark QCD Origin of the NANOGrav Signal and Self-Interacting Dark Matter

    Zihan Wang🇬🇧

    The NANOGrav 15-year stochastic gravitational wave background (SGWB) amplitude $A_{\mathrm{yr}}\approx 2.4\times 10^{-15}$ lies at the upper edge of population synthesis predictions for supermassive black hole binaries (SMBHBs), motivating exploration of additional cosmological sources. We present a phenomenological framework based on an $\text{SU}(3{)}_D$ gauge theory that can simultaneously accommodate the gravitational wave signal and resolve small-scale structure anomalies via Self-Interacting Dark Matter (SIDM). The dark matter candidate is a heavy dark baryon $\chi =QQQ$ with mass $m_{\chi }\approx 40$~GeV, which self-interacts through a light pseudo-dilaton $d$ $m_d\approx 20$--$50$~MeV as a pseudo-Goldstone boson of approximate scale invariance arising in near-conformal gauge theories with $N_f\sim 6$--$8$ light flavors. A first-order phase transition at the MeV scale, enabled by walking dynamics near the conformal window, produces gravitational waves in the PTA band. For representative parameters $T_n\approx 5$--$6$~MeV, $\alpha \sim 500$--$1000$, $\beta /H_{\ast }\sim 30$--$50$, the model provides a fit to NANOGrav data comparable to SMBHB while naturally connecting the gravitational wave amplitude to the dark matter relic density through entropy dilution $D\approx {\alpha }^{3/4}$. We present explicit calculations of the bounce action, bubble wall velocity, and $\Delta N_{\mathrm{eff}}$, demonstrating that the benchmark parameters are theoretically consistent and cosmologically safe ($\Delta N_{\mathrm{eff}}\lesssim 0.1$ for $m_{\pi }>2m_d$). The distinctive spectral shape ($f^3\to f^{-4}$) provides a robust prediction testable with future PTAs.

    ↳ astro-ph.COgr-qchep-ph2 citations
15. 15*

    Inflation and Primordial Perturbations in Fractal Cosmology

    Aarav Shah🇫🇷 · Paulo Moniz🇵🇹 · Maxim Khlopov🇫🇷 · Oem Trivedi🇺🇸 · Maxim Krasnov🇷🇺

    We study inflationary dynamics within the framework of fractal cosmology, where space is characterized by an effective non-integer dimension $D$. In our work, fractal effects are sourced through thermodynamic modifications at the cosmological horizon. Using the modified Friedmann and continuity equations, we then derive the modified slow roll parameter and their evolution for linear, cubic, Starobinsky ($R+R^2$) and Natural inflationary potentials, showing that the slow roll parameters get suppressed for $D<3$. We further derive a fractal extension of the Mukhanov-Sasaki equation by introducing an effective momentum $k_{\text{eff}}$, which captures the modification of spatial Laplacian due to fractality. This leads to explicit corrections to the scalar power spectrum and the spectral index $n_s$, depending on both $D$ and a fractional length scale $L$. Confrontation with Planck 2018 data constrains the effective dimension to a best-fit range of $2.7\lesssim D\lesssim 3$ for the Starobinsky model. Furthermore, in the case of Natural Inflation, fractal corrections relax the usual requirement of super-Planckian axion decay constants, opening a phenomenologically viable parameter space inaccessible in the standard $3+1$ dimensional cosmology.

    ↳ gr-qchep-phhep-thPhys.Dark Univ.(2026)·1 citation
16. 16*

    QCD Crossover at Low Temperatures from Lee-Yang Edge Singularity

    D. A. Clarke🇩🇪 · H.-T. Ding🇨🇳 · J.-B. Gu🇨🇳 · S.-T. Li🇨🇳 · Swagato Mukherjee🇺🇸 · P. Petreczky🇺🇸 · C. Schmidt🇩🇪 · H.-T. Shu🇨🇳 · K.-F. Ye🇨🇳

    We provide the first lattice-QCD estimate of the crossover line down to $T\simeq 108$~MeV. We introduce a new method that combines the Lee-Yang edge in the complex plane of baryon chemical potential ${\mu }_B$ with universal chiral scaling to determine the ${\mu }_B$ dependence of the QCD chiral critical and pseudo-critical temperatures. By performing $(2+1)$-flavor lattice QCD simulations at $T\simeq 108$~MeV and purely imaginary ${\mu }_B$ with a single lattice spacing and two volumes, we compute ${\mu }_B$-dependent baryon-number susceptibilities and extract the location of the Lee-Yang edge. Together with universal scaling near the QCD chiral transition, it constrains the mapping function between $\{T,{\mu }_B\}$ and the scaling variable (\textit{i.e.}\ the argument of the universal scaling functions). This mapping function then yields the ${\mu }_B$ dependence of the critical and pseudo-critical temperatures for $T\gtrsim 108$~MeV. While our calculation is performed only at a single value of low temperature without explicit input from small-${\mu }_B$ expansion, the resulting ${\mu }_B$ dependence of the pseudo-critical temperature is consistent with established lattice-QCD determinations at small ${\mu }_B$ and compatible with chemical freeze-out parameters of heavy-ion collisions down to low temperatures, demonstrating the validity and robustness of the method. Application of this method can be systematically extended to additional temperatures and finer discretizations, opening a pathway to charting the QCD phase diagram in the low-$T$, high-${\mu }_B$ regime.

    ↳ hep-lathep-phnucl-exnucl-th1 citation
17. 17*

    Constraining the Primordial Black Hole Abundance with Space-Based Detectors

    Wencong Hong🇨🇳 · Shi Pi🇨🇳 · Ao Wang🇨🇳 · Zhenyu Zhang🇨🇳

    Overdense regions can collapse into primordial black holes (PBHs) in the early universe, which are a compelling candidate for dark matter. Current constraints leave the asteroid-mass window the only possible one for PBH to account for all the dark matter, which can only be probed indirectly by the scalar-induced gravitational waves (GWs) sourced by the curvature perturbation which forms PBH. In this work, we explore the capabilities of future space-based gravitational wave detectors, including LISA, Taiji, and TianQin, to constrain such induced GWs as well as the PBH abundance. We systematically account for the width of the primordial curvature power spectrum, and find that the asteroid-mass window can be fully probed by all three space-based interferometers. If PBHs constitute the majority of dark matter, the induced GW leaves a strong signal in the mHz band with a signal-to-noise ratio of $10^3$--$10^4$.

    ↳ astro-ph.COgr-qchep-phhep-th5 citations
18. 18*

    Percolation and de-confinement in relativistic nuclear collisions

    B. K. Srivastava🇺🇸 · R. P. Scharenberg🇺🇸 · C. Pajares🇪🇸

    In the present work we have analyzed the transverse momentum spectra of charged particles in high multiplicity $pp$ collisions at LHC energies $\sqrt{s}$ = 5.02 and 13 TeV using the Color String Percolation Model (CSPM). For heavy ions $Pb-Pb$ at $\sqrt{s_{NN}}$ = 2.76 and 5.02 TeV along with $Xe-Xe$ at $\sqrt{s_{NN}}$= 5.44 TeV have been analyzed. The initial temperature is extracted both in low and high multiplicity events in $pp$ collisions. For $A-A$ collisions the temperature is obtained as a function of centrality. From the measured energy density $\epsilon$ and the temperature T the dimensionless quantity $\epsilon /T^4$ is obtained. Our results for Pb-Pb and Xe-Xe collisions show a sharp increase in $\epsilon /T^4$ above T $\sim$ 210 MeV and reaching the ideal gas of quarks and gluons value of $\epsilon /T^4\sim$ 16 at temperature $\sim$ 230 MeV. At this temperature there is a transition from the fluid behavior of QCD matter strongly interacting to a quasi free gas of quarks and gluons.

    ↳ nucl-exhep-exhep-phPoS(2026)·0 citations
19. 19*

    Extended Heun Hierarchy in Quantum Seiberg-Witten Geometry

    Peng Yang🇨🇳 · Yi-Rong Wang🇨🇳 · Kilar Zhang🇨🇳

    We investigate the quantum geometry of the Seiberg-Witten curve for $\mathcal{N}=2$, ${\mathrm{SU}(2)}^n$ linear quiver gauge theories. By applying the Weyl quantization prescription to the algebraic curve, we derive the corresponding second-order differential equation and demonstrate that it is isomorphic to the Extended Heun Equation with $n+3$ regular singular points. The physical parameters of the gauge theory are linked to the canonical coefficients of the Heun equation via a polynomial representation of the Seiberg-Witten curve. This framework provides the necessary mathematical foundation to apply non-perturbative gauge-theoretic techniques, such as instanton counting, to spectral problems in gravitational physics, most notably for higher-dimensional black holes.

    ↳ hep-thastro-ph.HEgr-qchep-ph+22 citations
20. 20*

    Towards a unified quantum field theory of dark energy and inflation: unstable de Sitter vacuum and running vacuum

    Joan Solà Peracaula🇪🇸 · Àlex González-Fuentes🇪🇸 · Cristian Moreno-Pulido🇪🇸

    Inflation is a necessary cosmic mechanism to cure basic inconsistencies of the standard model of cosmology. These problems are usually `fixed' by postulating the existence of a scalar field (called the ``inflaton''). However, other less ad hoc options are possible. In the running vacuum model (RVM) framework, the vacuum energy density (VED) ${\rho }_{\mathrm{vac}}$ is a function of the Hubble rate $H$ and its time derivatives. In this context, the VED is dynamical (there is no rigid cosmological constant $\Lambda$). In the FLRW epoch, ${\rho }_{\mathrm{vac}}$ evolves very slowly with expansion. In contrast, in the very early universe the vacuum fluctuations induce higher powers $H^N$ capable of unleashing fast inflation in a short period in which $H\simeq$ const. We call this mechanism `RVM-inflation'. It does not require an inflaton field since inflation is brought about by pure quantum field theory (QFT) effects on the dynamical background. It is different from Starobinsky's inflation, in which $H$ is never constant. In this work, we study a closely related scenario: the decay of the exact de Sitter vacuum into FLRW spacetime in its radiation epoch and the subsequent impact on the current universe, and compare with the RVM. We find that in both cases inflation is driven by $H^4$ powers together with subleading contributions of order $H^2$ that ease a graceful-exit transition into the radiation-dominated epoch, where the FLRW regime starts and ultimately develops a mildly evolving VED in the late universe: $\delta {\rho }_{\mathrm{vac}}\sim \mathcal{O}(m_{\mathrm{Pl}}^2{H}^2)$. The proposal presented here aims at a unified QFT approach to inflation and dark energy (conceived as dynamical vacuum energy) with potentially measurable phenomenological consequences in the present universe, and constitutes a first step toward establishing its full theoretical and phenomenological consistency.

    ↳ gr-qcastro-ph.COhep-phhep-thClass.Quant.Grav.(2026)·10 citations
21. 21*

    Mimicking Phantom Dark Energy with Evolving Dark Matter Mass

    Lorenzo La Penna🇮🇹 · Alessio Notari🇮🇹 · Michele Redi🇮🇹

    We present a general method to reproduce a given cosmological background through energy exchange between dark energy (DE) and dark matter (DM). This can be simply realized with a standard quintessence scalar field that controls the DM mass. In particular a background with phantom crossing can be effectively realized without introducing ghosts or other pathologies. For example one can reproduce exactly the background that gives the best fit to the recent DESI+CMB+DESY5 data, within the Chevallier-Polarski-Linder (CPL) parametrization of DE. Although the background evolution is identical, the perturbations differ, leading to modified growth of structures. If the DM mass varies at late times, early-time observables are not modified and can reproduce the main predictions of the target model, but late-time observables are affected. We discuss in particular the effects on the matter power spectrum, CMB lensing and ISW effect. When reproducing the best fit CPL background model, this scenario generically predicts $\mathcal{O}(10\%)$ deviations in such observables. However, for suitable choices of parameters, effects on the matter power spectrum can be smaller, motivating a detailed study. In general, energy exchange between DE and DM generates a mismatch between the matter power spectrum and the gravitational potential amplitudes compared to the decoupled case, that can lead to deviations observable in future experiments.

    ↳ astro-ph.COhep-phJCAP(2026)·10 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.