Fri·Nov 7, 2025Friday·November 7, 2025

1. 01*

   Characterizing the initial state of hydrodynamics in pp and pA collisions

   Gabriel Rabelo-Soares🇧🇷 · Gojko Vujanovic🇨🇦 · Giorgio Torrieri🇧🇷

   The observation of seeming hydrodynamic-like behavior in proton-proton and proton-nucleus collisions presents us with the conceptual problem of how the initial state of such a hydrodynamic evolution should be characterized. This is an issue because, while nuclei can reasonably be approximated as ``large'' systems w.r.t. the characteristic Fermi momentum of their constituents, this is no longer true for nucleons. Hence, one would need to match a ``quantum'' theory, whose observables are described via highly non-commuting operators, to a ``classical'' hydrodynamics. Operationally assuming a ``fast'' thermalization, we survey what kind of object is best suited to such a matching condition. We show that it cannot be any of the objects usually associated with ``the 3D structure of the nucleon'' but rather a measure associated with entanglement entropy.

   hep-phnucl-th3 citations
2. 02*

   Probing Standard Model-like di-Higgs Production at Photon-Photon Colliders in the I(1+2)HDM Type-I

   Abdesslam Arhrib🇲🇦 · Ayoub Hmissou🇲🇦 · Stefano Moretti🇬🇧 · Larbi Rahili🇲🇦

   In this paper, pair production of Standard Model (SM)-like Higgs bosons, $hh$, is studied through $\gamma \gamma$ scattering at future electron-positron colliders, in the framework of the Inert Doublet Model with two Active Doublets, i.e., the I(1+2)HDM for short. The relevance of the process $\gamma \gamma \to hh$ for such a Beyond the SM (BSM) scenario stems from the fact that it is a one-loop process at lowest order, wherein inert charged states ${\chi }^{\pm }$ contribute alongside with $W^{\pm }$, $H^{\pm }$ and heavy fermions (primarily, bottom and top quarks), crucially, at the same perturbative order. {{Given that ${\chi }^{\pm }/H^{\pm }$ masses and $h{S}^{+}{S}^{-}$ ($S^{\pm }={\chi }^{\pm },H^{\pm }$) couplings are very mildly constrained,}} there exist regions of the parameter space of the I(1+2)HDM where the former can be rather light and the latter rather large. After imposing up-to-date theoretical and experimental constraints on the I(1+2)HDM, it is found that the production rates of such process at future $\gamma \gamma$ machines can be enhanced up to a factor of $\approx$ $50$ with respect to the SM, significantly exceeding typical yields of conventional 2-Higgs Doublet Models (2HDMs). Further, thanks to the level of control that one can attain at such facilities on the photon kinematics, leading to excellent invariant mass resolution of the incoming photon pairs, we show how it is possible to extract from this process the value of the ${\chi }^{\pm }$ mass (along that of the active $H^{\pm }$ states) with high precision, whichever the decays of the $hh$ pair, both with and without beam polarization.

   hep-phPRD(2026)·2 citations
3. 03*

   Scale-independent relations between neutrino mass parameters

   Mu-Chun Chen🇺🇸 · Shaheed Perez🇺🇸 · Michael Ratz🇺🇸

   Theories of flavor operate at various scales. Recently it has been pointed out that in the context of modular flavor symmetries certain combinations of observables are highly constrained, or even uniquely fixed, by modular invariance and holomorphicity. We find that even in the absence of supersymmetry these combinations are surprisingly immune against quantum corrections. This applies, in particular, to the standard model (SM) and certain 2-Higgs doublet models (2HDMs).

   hep-phUniverse(2026)·3 citations
4. 04*

   Validating a Machine Learning Approach to Identify Quenched Jets in Heavy-Ion Collisions

   Yilun Wu🇨🇳 · Yi Chen🇺🇸 · Julia Velkovska🇺🇸

   Jet quenching is a phenomenon in heavy-ion collisions arising from jet interactions with the quark-gluon plasma (QGP). Its study is complicated by the interplay of multiple physics processes that affect jet observables. In addition, detector effects may influence the results and must be accounted for when identifying quenched jets. We employ a Long Short-Term Memory (LSTM) neural network trained on jet substructure, incorporating parton shower history, to predict jet-by-jet quenching levels. Using photon-jet samples from the \textsc{Jewel} event generator, we show that the LSTM predictions strongly correlate with true jet energy loss. This validates that the model effectively learns the features of jet-QGP interaction. We simulate detector effects using \textsc{Delphes} simulation framework and demonstrate that the method identifies quenching effects in a realistic environment. We test the approach with photon-jet momentum imbalance, jet fragmentation function, and jet shape, which were not included in the training, confirming its ability to distinguish true quenching features.

   hep-phnucl-exJHEP(2026)·1 citation
5. 05*

   Decay and production properties of strange double charm pentaquark

   Zi-Yan Yang🇨🇳 · Wei Chen🇨🇳

   In this work we investigate the decay and production properties of the strange double-charm pentaquark $P_{ccs}^{++}$ with strangeness $S=-1$. Building upon our previous work predicting its $J^P=1/2^{-}$ molecular configuration, we employ three-point QCD sum rules to calculate its strong decay widths and estimate its production branching ratio via ${\Xi }_{bc}^{+}$ baryon decays. The total strong decay width to the ${\Xi }_{cc}\bar{K}$ and ${\Omega }_{cc}\pi$ final-state channels is determined as $85\pm 19$ MeV. Furthermore, using a rescattering mechanism, we analyze the ${\Xi }_{bc}^{+}\to D_s^{\ast -}{\Xi }_{cc}^{++}\to D^{-}{P}_{ccs}^{++}$ process and estimate the production branching ratio to be $\mathcal{B}r({\Xi }_{bc}^{+}\to D^{-}{P}_{ccs}^{++})=(4.3_{-1.5}^{+2.0})\times 10^{-6}$. The relatively narrow width and detectable branching ratio suggest the possibility searching for this pentaquark state in the future.

   hep-phPRD(2026)·2 citations
6. 06*

   Soft-contribution to thermal photon emission from chiral QCD medium

   Nilanjan Chaudhuri🇮🇳 · Sourav Duari🇮🇳 · Pradip Roy🇮🇳 · Sourav Sarkar🇮🇳

   We evaluate the thermal photon emission rate from a chirally asymmetric quark gluon plasma using the Hard Thermal Loop approximation. The quasiparticle and plasmino modes prevalent at finite temperature split into L and R-modes in the presence of chiral imbalance and are found to disperse differently acquiring different thermal masses. The soft contribution to the thermal photon emission rate obtained from the retarded self-energy is found to contain additional terms proportional to the square of the quark and chiral chemical potentials which is found to cause an enhancement to thermal photon emission in the presence of chiral imbalance.

   hep-phPRD(2025)·1 citation
7. 07*

   Predictive one-zero with vanishing sub-trace texture in neutrino mass matrix in light of dark matter and neutrinoless double beta decay

   Ankush · Sangeeta Dey🇮🇳 · Rishu Verma🇮🇳 · Manoj Kumar🇮🇳 · B.C.Chauhan · Mahadev Patgiri🇮🇳

   In this work, we investigate a predictive class of neutrino mass matrices characterized by one texture zero and one vanishing sub-trace within the framework of the scotogenic model, wherein neutrino masses, dark matter, and neutrinoless double beta decay are intrinsically correlated. We analyze twelve viable texture structures -- namely $B_{1,4,5}$, $C_{1,2,\dots ,5}$, $D_{4,5}$, and $F_{5,6}$ -- and examine their implications for the effective Majorana mass $(|M_{ee}|)$ governing neutrinoless double beta decay $(0\nu \beta \beta )$. Remarkably, all non-zero entries of the neutrino mass matrix can be parametrized in terms of this effective Majorana mass, establishing a direct theoretical link between low-energy observables and high-scale parameters of the model. Among the twelve textures, eleven predict dark matter masses of order TeV and yield correlated bounds on $|M_{ee}|$ -- making them testable in current and forthcoming $0\nu \beta \beta$ experiments -- while the textures $D_4$ and $F_{5,6}$ exhibit comparatively weaker correlations. In contrast, the texture $C_5$ is excluded due to its requirement of unrealistically large Yukawa couplings and its inability to realize dark matter in the TeV regime. Our analysis thus identifies a subset of predictive neutrino mass textures that consistently relate dark matter phenomenology and neutrinoless double beta decay observables within the scotogenic paradigm.

   hep-phPhys.Dark Univ.(2026)·0 citations
8. 08*

   Reply to "Clearing up the Strong $CP$ problem"

   Wen-Yuan Ai🇦🇹 · Björn Garbrecht🇩🇪 · Carlos Tamarit🇩🇪

   The conservation of $CP$ in QCD has been shown to follow from a careful treatment of the path integral and canonical quantization in arXiv:2001.07152 and arXiv:2403.00747. Here, we refute the critique of these results put forth in arXiv:2510.18951. First, using the quantum rotor as an analogue of QCD, it is argued in arXiv:2510.18951 that the topological susceptibility vanishes when using the limiting procedure of arXiv:2001.07152. When translated to QCD, this would contradict the observed ${\eta }^{\prime }$-mass. We show that this is not the case because the susceptibility is defined from the vacuum correlator of the topological charge density, which for the rotor is just fixed by the canonical commutation relation. The latter does not depend on the disputed order of limits. Second, it is suggested in arXiv:2510.18951 that $CP$ violation in QCD can be established by considering the low-energy effective theory alone. We show that here the argument relies on assuming from the start choices of couplings that lead to $CP$ violation but are not of the most general form allowed by spurion analysis. No valid reason is given for why allowed choices leading to $CP$ conservation, that match the computation of ultraviolet correlators as shown in arXiv:2001.07152 and arXiv:2403.00747, would be inconsistent.

   hep-phhep-th7 citations
9. 09*

   Investigation of the ratio $\frac{{\sigma }_r}{F_2}(Q^2/s,Q^2)$ in the momentum-space approach

   G.R.Boroun🇮🇷

   We present a calculation of the ratio $\frac{{\sigma }_r}{F_2}(x,Q^2)$ in momentum-space approach using the Block-Durand-Ha (BDH) parameterization of the proton structure function $F_2(x,Q^2)$. The results are compared with H1 data and extended to high inelasticity. We also examine the ratio $\frac{{\sigma }_r}{F_2}(\frac{Q^2}{s},Q^2)$ obtained at a fixed $\sqrt{s}$ and $Q^2$ to the minimum value of $x$ given by $Q^2/s$, comparing them with both the HERA data and the color dipole model bounds. These results and comparisons with HERA data demonstrate that the suggested method for the ratio $\frac{{\sigma }_r}{F_2}$ can be applied in analyses of the Large Hadron Collider and Future Circular Collider projects. The effect of adding a simple higher twist term of the form $F_2\ast H_2/Q^2$ to the description of the ratio $\frac{{\sigma }_r}{F_2}(\frac{Q^2}{s},Q^2)$ at low-$x$ and low-$Q^2$ values for comparison with the color dipole bounds and the HERA data is investigated.

   hep-phPRC(2026)·0 citations
10. 10*

    Determination of quark-gluon-quark interference within the proton

    Alexey Vladimirov🇪🇸 · Guillermo Portela🇪🇸 · Simone Rodini🇩🇪

    Quarks and gluon, as quantum particles, are subjects to various effects that go beyond the naive parton picture and are not captured by ordinary parton densities. In this work, we investigate the twist-three parton distribution functions, which encode quantum interference between quark-gluon-quark states, and for the first time, determine them directly from experimental data. The analysis combines observables described by collinear and transverse-momentum-dependent factorization theorems within a unified global fit, incorporating a complete leading-order QCD evolution at the twist-three level. The extracted distributions reveal a clear flavor-dependent patterns and distinct from zero at a statistically significant level ($2-3\sigma$). These findings provide the first quantitative evidence for quark-gluon-quark correlations within the proton, revealing its genuinely quantum nature and opening a new direction for precision studies of partonic correlations.

    hep-phhep-latquant-phPRL(2026)·6 citations
11. 11*

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

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

    We consider the exclusive photoproduction of a di-meson pair with large invariant mass, $\gamma N\to N^{\prime }{M}_1{M}_2$, in the framework of collinear factorisation. The mesons considered $M_1$ and $M_2$ are either pions or rho mesons, charged or neutral. We consider the kinematic regime characterised by a large invariant mass of the two-meson system, and a small deflection of the nucleon in the centre-of-mass frame. In this kinematic domain, the amplitude factorises into a perturbative hard part and non-perturbative parts described by Generalised Parton Distributions (GPDs) and Distribution Amplitudes (DAs). We automate the calculation of the fully differential cross section at leading twist and leading order, and we present some numerical results at JLab 12 GeV kinematics. This class of processes provides yet more exclusive $2\to 3$ channels that can be used to extract GPDs.

    hep-phhep-exnucl-exnucl-th1 citation
12. 12*

    Emerging Narrow Resonance at 152 GeV

    Srimoy Bhattacharya🇿🇦 · Mukesh Kumar🇿🇦 · Rachid Mazini🇿🇦 · Bruce Mellado🇿🇦

    The discovery of the Higgs boson at the LHC completed the Standard Model (SM), yet the possibility of additional scalars remains open, provided their contributions to electroweak symmetry breaking are sufficiently small. Recent analyses of LHC data have revealed statistically significant anomalies in multi-lepton final states - events characterized by multiple leptons, missing transverse energy, and ($b$-)jets. These anomalies provide intriguing hints of physics beyond the SM. In this work, we present the signature of growing excesses for a new scalar resonance with a mass of $152\pm 1$ GeV, observed in the $\gamma \gamma$, $Z\gamma$, and $WW$ channels. The combined global significance reaches a level that points toward the growing signature of this resonance. The findings align with a simplified model in which a heavy scalar boson decays into two lighter scalars, thus providing a consistent framework explaining the observed multi-lepton anomalies. These results significantly advance the search for new scalar bosons at the electroweak scale. Future investigations, including precision studies with upcoming HL-LHC data, will be crucial for confirming the nature of this resonance and exploring its implications for extending the SM.

    hep-phPoS(2025)·0 citations
13. 13*

    Diboson production in the SMEFT at dimension-8

    Hesham El Faham🇬🇧 · Giuseppe Ventura🇬🇧 · Eleni Vryonidou🇬🇧

    We present a comprehensive analysis of dimension-8 and dimension-6 effects in fully leptonic $WZ$ and $WW$ production at the Large Hadron Collider (LHC) within the Standard Model (SM) Effective Field Theory (SMEFT). We focus on dimension-8 operators with maximal energy growth in the quark-(anti)quark-initiated production channel and assess their impact differentially through a variety of observables, including polarisation-sensitive ones. Leveraging existing data from measurements at the LHC, we perform fits to quantify the sensitivity of current and future data to dimension-8 effects and evaluate their interplay with squared dimension-6 contributions. By marginalising over the dimension-8 operators we examine the robustness of a dimension-6 SMEFT analysis in diboson production. We find that dimension-8 effects become subdominant only for new-physics scales above 3 TeV.

    hep-phJHEP(2026)·7 citations
14. 14*

    Emergence of kaonium as a sharp resonance in photon-photon to meson-meson cross-sections

    Alireza Beygi🇩🇪 · S. P. Klevansky🇩🇪 · R. H. Lemmer🇿🇦

    We calculate the binding energies of the hypothetical mesonic atom, $K^{+}{K}^{-}$ (kaonium), using the $K^{+}{K}^{-}\to K^{+}{K}^{-}$ elastic scattering amplitude. Our findings are in line with previously reported results, which involve solving an eigenvalue equation of the Kudryavtsev-Popov type. Using chiral perturbation theory, we show that kaonium manifests itself as a sharp resonance around 992 MeV accompanying $f_0(980)$ or $a_0(980)$ in cross-sections for processes $\gamma \gamma \to {\pi }^0{\pi }^0$ or $\gamma \gamma \to {\pi }^0\eta$. The latter process is particularly striking: the peak at the kaonium resonance energy is highly pronounced, with the ratio of the cross-sections $\sigma (\gamma \gamma \to {\pi }^0\eta )/\sigma (\gamma \gamma \to {\pi }^0{\pi }^0)\approx 9$. Due to the short lifetime of kaonium ($\sim 10^{-18}$ s) and its small decay width ($\sim 0.4$ keV), direct detection of this exotic atom poses a significant challenge and requires high experimental resolution. However, we show that once the formation of kaonium is considered in the cross-section, a better fit to the available experimental data is obtained.

    hep-phnucl-thPRD(2026)·0 citations
15. 15*

    Constraining the four-light quark operators in the SMEFT with multijet and VBF processes at linear level

    Céline Degrande🇧🇪 · Matteo Maltoni🇧🇪

    We investigate how the interference of the SM with ten four-light quark operators in the SMEFT can be constrained thanks to multijet and $Z$, $W$, $\gamma$ VBF production in association with jets. The differential distributions for each process are generated at LO for different jet multiplicities, that are then merged and showered. We check which observables provide better bounds on the Wilson coefficients, and what directions in the ten-dimensional coefficient space they are able to probe. We discuss the relevance of the quadratic contributions with respect to the linear terms and use them to assess the validity of the EFT approach.

    hep-phJHEP(2026)·1 citation
16. 16*

    On the origin of CP symmetry violations

    Jean-Marcel Rax🇫🇷

    Experiments devoted to charge parity (CP) violation are normally interpreted by adjusting the elements of the Cabibbo-Kobayashi-Maskawa matrix to the measured violation parameters. However, the physical origin of these violations remains an open issue. To resolve this issue, the impact of Earth's gravity on meson oscillations is analysed. The effect of gravity is to couple flavour oscillations to quark zitterbewegung oscillations, and this coupling induces a superposition of CP eigenstates. The three types of CP violation effects result from this gravity-induced mixing. The three associated violation parameters are predicted in agreement with experimental data. The amplitude of the violation is linear with respect to gravity, so this new mechanism allows us to envisage cosmological evolutions that provide the observed baryonic asymmetry of the universe.

    hep-phhep-th0 citations
17. 17*

    Probing quantum entanglement with Generalized Parton Distributions at the Electron-Ion Collider

    Yoshitaka Hatta🇺🇸 · Jakob Schoenleber🇺🇸

    Within the collinear factorization framework based on Generalized Parton Distributions (GPDs), we calculate the spin density matrix of exclusively produced quark and antiquark pairs $u\bar{u}$, $d\bar{d}$, $s\bar{s}$, $c\bar{c}$, $b\bar{b}$ in electron-proton scattering. The presence of both real and imaginary parts in the scattering amplitudes leads to a rich pattern of entanglement between the quark and the antiquark. We map out kinematical regions where the pairs exhibit entanglement, Bell nonlocality and non-stabilizerness (`magic'). We also predict that massive quarks and antiquarks are transversely polarized, similar to the well-known transverse hyperon polarization in unpolarized collisions. In strangeness, charm and bottom productions, the polarization can reach 50-80\% in certain kinematic regions in the low-energy runs of the Electron-Ion Collider.

    hep-phhep-exquant-phPRD(2026)·13 citations
18. 18*

    Flavour universality of the $W^{\pm }$ and $Z$ fermionic couplings

    Antonio Pich🇪🇸

    The Standard Model does not provide any dynamical explanation of the existence of different families of fermions. To account for this experimental fact, it just replicates three times its single-family gauge structure. The equal-charge fermions of the different families couple to the gauge bosons with exactly the same coupling strength. We overview the empirical evidence supporting this important property. The currently most precise experimental tests on the universality of the lepton and quark couplings are discussed. Both charged-current ($W^{\pm }$) and neutral-current ($Z$) interactions are reviewed.

    hep-phhep-ex1 citation
19. 19*

    Electroweak phase transition enhanced by a CP-violating dark sector

    Venus Keus🇮🇪 · Lucy Lewitt🇬🇧 · Jasmine Thomson-Cooke🇮🇪

    Within a well-motivated 3-Higgs doublet model, in which the extended dark sector accommodates CP violation, we analyse the electroweak phase transition (EWPT) at one- and two-loop order. We show the importance of higher loop calculations in EWPT analyses and identify the regions of the parameter space of our model where EWPT is of first order while in agreement with all theoretical and experimental bounds, including Dark Matter relic density and direct and indirect searches.

    hep-phhep-th6 citations
20. 20*

    Higgs inflation in Weyl-invariant Einstein-Cartan gravity

    Georgios K. Karananas🇩🇪 · Mikhail Shaposhnikov🇨🇭

    In this short note we analyze the inflationary dynamics in Weyl-invariant Einstein-Cartan gravity coupled to the Standard Model of particle physics. We take the axion-like particle of gravitational origin to be approximately massless in the early Universe and show how inflation with the Higgs field materializes.

    hep-phastro-ph.COgr-qchep-thPLB(2026)·4 citations
21. 21*

    NuFast-Earth: Efficient Atmospheric, Solar, and Supernova Neutrino Propagation Through the Earth

    Peter B. Denton🇺🇸 · Stephen J. Parke🇺🇸

    Algorithms for computing neutrino oscillation probabilities in sharply varying matter potentials such as the Earth are becoming increasingly important. As the next generation of experiments, DUNE and HyperK as well as the IceCube upgrade and KM3NeT, come online, the computational cost for atmospheric and solar neutrinos will continue to increase. To address these issues, we expand upon our previous algorithm for long-baseline calculations to efficiently handle probabilities through the Earth for atmospheric, nighttime solar, and supernova neutrinos. The algorithm is fast, flexible, and accurate. It can handle arbitrary Earth models with two different schemes for varying density profiles. We also provide a c++ implementation of the code called NuFast-Earth along with a detailed user manual. The code intelligently keeps track of repeated calculations and only recalculates what is needed on each successive call which can also help provide significant speed-ups.

    hep-phhep-exPRD(2026)·2 citations
22. 22*

    Effective Field Theories for Neutron Stars Physics

    J. M. Alarcón🇪🇸 · E. Lope-Oter🇪🇸 · Y. Cano🇪🇸

    There is an increasing interest in the community for the Neutron Stars and what we can learn from them. In this review we show how chiral effective field theory, combined with many-body methods, can provide important results that connect Neutron Star properties at zero temperature to nuclear physics and allows to use these compact objects as laboratories of new physics.

    hep-phastro-ph.HEnucl-thEur.Phys.J.direct(2025)·7 citations
23. 23*

    Fast and Flexible Neutrino Decoupling Part I: The Standard Model

    M. Escudero🇨🇭 · G. Jackson🇫🇷 · M. Laine🇨🇭 · S. Sandner🇺🇸

    Cosmological determinations of the number of relativistic neutrino species, $N_{\mathrm{eff}}^{}$, are becoming increasingly accurate, and further improvements are expected both from CMB and BBN data. Given this context, we update the evaluation of $N_{\mathrm{eff}}^{}$ and the current entropy density via the momentum-averaged approach. This allows for a numerically fast description of neutrino decoupling, easily portable to an array of new physics scenarios. We revisit all aspects of this approach, including collision terms with full electron mass dependence, finite temperature QED corrections to the equation of state, neutrino oscillations, and the modelling of neutrino ensembles with effective chemical potentials. For integrated observables, our results differ by less than $0.04\%$ from the solution of the momentum-dependent evolution equation. We outline how to extend the approach to BSM settings, and will highlight its power in Part II. To facilitate the practical implementation, we release a Mathematica and Python code within nudec_BSM_v2, easily linkable to BBN codes.

    hep-phastro-ph.COJCAP(2026)·18 citations
24. 24*

    String geometry phenomenology

    Matsuo Sato🇯🇵 · Maki Takeuchi🇯🇵

    Recently, a potential for string backgrounds is obtained from string geometry theory, which is a candidate for the non-perturbative formulation of string theory. By substituting a string phenomenological model with free parameters to the potential, one obtains a potential for the free parameters, whose minimum determines the free parameters. The model with the determined parameters is the ground state in the model. This will be the local minimum in a partial region of the model in the string theory landscape. By comparing it with the other local minimum, one can determine which model is near the minimum of the potential for string backgrounds, that will be the true vacuum in string theory, in the sense of the values of the potential. We will be able to find the true vacuum in string theory through a series of such researches. In this paper, we perform this analysis of a certain simple heterotic non-supersymmetric model explicitly, where the six-dimensional internal spaces are products of two-dimensional spaces of constant curvatures, and the generation number of massless fermions is given by the flux quantization numbers. As a result, we obtain a constraint between the compactification scale and the flux quanta.

    ↳ hep-thhep-ph2 citations
25. 25*

    Two-exponential decay of Acridine Orange

    Francesco Giacosa🇵🇱 · Anna Kolbus🇵🇱 · Krzysztof Kyziol🇵🇱 · Magdalena Plodowska🇵🇱 · Milena Piotrowska🇵🇱 · Karol Szary🇵🇱 · Arthur Vereijken🇵🇱

    In this work, we experimentally study the fluorescence decay of Acridine Orange at late times, in order to test whether a late-time power-law behaviour emerges, a feature expected to be very small but consistent with quantum mechanical and quantum field theoretical predictions. Using two distinct photon detectors, we find that the data are well described by a sum of two exponential functions with lifetimes ${\tau }_1=1.7331\pm 0.001$ ns and ${\tau }_2=5.948\pm 0.012$ ns, in agreement with values reported in the literature. While no deviation from the exponential decay law is observed, this study serves as a reliable test for the experimental setup and enables a precise determination of the sample lifetimes.

    ↳ quant-phhep-phACTA PHYSICA POLONICA A No 6 Vol.148 (202…·1 citation
26. 26*

    Predictions of baryon directed flow in heavy-ion collisions at high baryon density

    Yuri B. Ivanov🇷🇺

    Predictions of the proton directed flow ($v_1$) in semicentral Au+Au collisions in the energy range between 4.5 and 7.7 GeV are done. The calculations are performed within the model of three-fluid dynamics with crossover equation of state, which well reproduces the proton $v_1$ both below 4.5 GeV and above 7.7 GeV, as well as bulk observables in the energy range of interest. It is predicted that the proton flow evolves non-monotonously. At the energy of 7.2 GeV it exhibits antiflow (i.e. negative slope of $v_1(y)$) in the midrapidity. At 7.7 GeV, the flow returns to the normal pattern in accordance with the STAR data. The midrapidity $v_1$-slope excitation functions within the first-order phase and crossover transitions to quark-gluon phase (QGP) turn out to be qualitatively similar, but the amplitude of the wiggle in the crossover scenario is much smaller than that in the strong first-order phase transition. Therefore, the change of sign followed by minimum at 7.2 GeV in the $v_1$-slope excitation function indicates onset of (weak phase or crossover) transition to QGP. The second change of the sign around 10 GeV results from interplay between incomplete baryon stopping and transverse expansion of the system.

    ↳ nucl-thhep-phnucl-exPRC(2026)·1 citation
27. 27*

    NANOGrav 15-year gravitational-wave signals from binary supermassive black-holes seeded by primordial black holes, and implications for the origins of Little Red Dots

    Mikage U. Kobayashi🇯🇵 · Kazunori Kohri🇯🇵

    In this paper, we explain the recently reported a nHz-band gravitational-wave background from NANOGrav 15-year through the merger of binary super-massive black holes with masses of $10^9{M}_{\odot }$ formed by the growth of primordial black holes. When a primordial black hole accretes at a high accretion rate, it emits a large number of high-energy photons. These heat the plasma, causing high-redshift cosmological 21cm line emission. Since this has not been detected, there is a strict upper bound on the accretion rate. We have found that with the primordial black hole abundance $10^{-14}\lesssim f_{\mathrm{PBH}}\lesssim 10^{-12}$ and the mass $1M_{\odot }\lesssim m_{\mathrm{PBH}}\lesssim 10^3{M}_{\odot }$, we successfully fit the nHz band gravitational wave background from NANOGrav 15-year while avoiding the 21 cm line emission. In addition, we also discuss the implication for the origins of the Little Red Dots. We propose that future observations of the gravitational wave background and the cosmological 21cm line can test this scenario.

    ↳ astro-ph.COastro-ph.HEgr-qchep-phPRD(2026)·3 citations
28. 28*

    Geometric unification of timelike orbital chaos and phase transitions in black holes

    Shi-Hao Zhang🇨🇳 · Zi-Yuan Li🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳

    The deep connection between black hole thermodynamics and spacetime geometry remains a central focus of general relativity. While recent studies have revealed a precise correspondence for null orbits, given by $K=-{\lambda }^2$ between the Gaussian curvature $K$ and the Lyapunov exponent $\lambda$, its validity for timelike orbits had remained unknown. Our work introduces the massive particle surface (MPS) framework and constructs a new geometric quantity $\mathcal{G}$. We demonstrate that $\mathcal{G}\propto -{\lambda }^2$ on unstable timelike orbits, thus establishing the geometry-dynamics correspondence for massive particles. Crucially, near the first-order phase transition of a black hole, $\mathcal{G}$ displays synchronized multivalued behavior with the Lyapunov exponent $\lambda$ and yields a critical exponent $\delta =1.0244$. Our results demonstrate that spacetime geometry encodes thermodynamic information, opening a new pathway for studying black hole phase transitions from a geometric perspective.

    ↳ gr-qchep-phhep-th2 citations
29. 29*

    Classification of four-quark operators with $\Delta F\le 2$ under flavor symmetry and their renormalization in a gauge-invariant scheme

    Gregoris Spanoudes🇨🇾 · Marios Costa🇨🇾 · Kyproulla Mitsidi🇨🇾 · Haralambos Panagopoulos🇨🇾

    In this paper we study a complete set of scalar and pseudoscalar four-quark operators, with a particular emphasis on their renormalization within a Gauge-Invariant Renormalization Scheme (GIRS). We focus on operators that do not mix with lower-dimensional operators by virtue of their transformation properties under the flavor-symmetry group. This class includes all $\Delta F=2$ operators, as well as their partners that transform under the same irreducible representations of the flavor group. These encompass a substantial subset of $\Delta F=1$ and $\Delta F=0$ operators. The present analysis provides a detailed classification of all four-quark operators, exploring their Fierz identities, symmetry properties, and mixing patterns. Different variants of GIRS are explored, including a democratic version that treats all mixing operators uniformly. For selected variants, which exhibit smaller mixing effects, we present the conversion matrices from GIRS to the $\overline{\text{MS}}$ scheme at next-to-leading order.

    ↳ hep-lathep-phPRD(2026)·1 citation
30. 30*

    A phenomenological model of magnetic flux tubes in strong fields induced by axion-origin photons

    Vitaliy Rusov🇺🇦 · Tatiana Zelentsova🇺🇦

    We propose a phenomenological model in which empty flux tubes in strong magnetic fields are associated with both the conversion of axions to photons of axion origin to generate coronal heating, and the simultaneous preservation of the Parker-Biermann cooling effect by converting high-energy photons from the radiative zone to axions from the convective zone through the O-loop tachocline, is the source of the rise of the magnetic flux tube from the tachocline to the photosphere in the form of sunspots. The model is characterized by two free parameters, justified by existing theoretical and observational constraints, the axion mass m_a ~3.2*10^{-2} eV, and asymmetric dark matter (ADM) with a particle mass m_ADM ~5 GeV gravitationally captured by the Sun. In this scenario, temporal modulations of the axion density are caused by anticorrelated 11-year modulations of ADM gravitationally captured by the Sun. We also obtained theoretical estimates of the velocities and times in empty magnetic tubes in strong fields rising from the tachocline to the surface of the photosphere in the form of sunspots. This ensured complete agreement with known experimentally measured velocities and times using local helioseismological time-distance inversions along the ray trajectories of acoustic waves. This allows us to study not only the subsurface structure and dynamics of active regions, but also the depths of the empty magnetic flux tube, extending up to 200,000 km from the tachocline to the photosphere. The proposed model links the phenomenology of axions with the magnetic structures of the Sun and provides testable consequences for astrophysical and solar observations.

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

    Gauge and diffeomorphism invariance from quantum information principles

    Claudia Núñez🇪🇸 · Miguel Pardina🇪🇸 · Manuel Asorey🇪🇸 · José Ignacio Latorre🇸🇬 · Alba Cervera-Lierta🇪🇸

    Entanglement is a hallmark of quantum theory, yet it alone does not capture the full extent of quantum complexity: some highly entangled states can still be classically simulated. Non-classical behavior also requires magic, the non-Clifford component that enables universal quantum computation. Here, we investigate whether the interplay between entanglement and magic-state resources constrains the structure of fundamental interactions. We study gluon-gluon and graviton-graviton scattering at tree level. We focus on the high-energy limit, where mass-dependent terms are negligible, and conformal symmetry is preserved. In this regime, all particles behave as massless degrees of freedom, allowing to isolate their transverse helicities as two-qubit states. We explicitly break gauge and general covariance by modifying the quartic vertices and analyzing the resulting generation of entanglement and magic. We find that imposing maximal entanglement (MaxEnt) alone does not uniquely recover gauge-invariant and diffeomorphism invariant interactions, but adding the condition of minimal, but nonzero, magic-state generation singles it out. Our results indicate that nature favors MaxEnt and low magic: maximal quantum correlations with limited non-Cliffordness, sufficient for universal quantum computing but close to classical simulability. This dual informational principle may underlie the emergence of gauge invariance in fundamental physics.

    ↳ hep-thhep-phquant-phPRD(2026)·11 citations
32. 32*

    Supersymmetry Breaking with Fields, Strings and Branes

    E. Dudas🇫🇷 · J. Mourad🇫🇷 · A. Sagnotti🇮🇹

    The first part of this review tries to provide a self-contained view of supersymmetry breaking from the bottom-up perspective. We thus describe N=1 supersymmetry in four dimensions, the Standard Model and the MSSM, with emphasis on the ``soft terms'' that can link it to supergravity. The second part deals with the top-down perspective. It addresses, insofar as possible in a self-contained way, the basic setup provided by ten-dimensional strings and their links with supergravity, toroidal orbifolds, Scherk-Schwarz deformations and Calabi-Yau reductions, before focusing on a line of developments that is closely linked to our own research. Its key input is drawn from ten-dimensional non-tachyonic string models where supersymmetry is absent or non-linearly realized, and runaway ``tadpole potentials'' deform the ten-dimensional Minkowski vacua. We illustrate the perturbative stability of the resulting most symmetrical setups, which are the counterparts of circle reduction but involve internal intervals. We then turn to a discussion of fluxes in Calabi-Yau vacua and the KKLT setup, and conclude with some aspects of Cosmology, emphasizing some intriguing clues that the tadpole potentials can provide for the onset of inflation. The appendices collect some useful material on global and local N=1 supersymmetry, in components and in superspace, on string vacuum amplitudes, and on convenient tools used to examine the fluctuations of non-supersymmetric string vacua.

    ↳ hep-thgr-qchep-phmath-ph+1Phys.Rept.(2026)·14 citations
33. 33*

    Study the nature of dynamical dark energy by measuring the CMB polarization rotation angle

    Hua Zhai🇨🇳 · Si-Yu Li🇨🇳 · Yang Liu🇨🇳 · Yiwei Zhong🇨🇳 · Hong Li🇨🇳 · Yaqiong Li · Congzhan Liu🇨🇳 · Mingzhe Li🇨🇳 · Xinmin Zhang🇨🇳

    Recent results from the Dark Energy Spectroscopic Instrument (DESI) support the dynamical dark energy. Intriguingly, the data favor a transition of the dark energy equation of state across $w=-1$, a hallmark of the Quintom scenario. In this paper, we consider a different approach to the dynamical nature of dark energy by investigating its interaction with ordinary matters, specifically the Chern-Simons (CS) interaction with photons. In cosmology, this interaction rotates the polarized plane of the cosmic microwave background (CMB) photons, which induces non-zero polarized TB and EB power spectra. We forecast this measurement with the Ali CMB Polarization Telescope (AliCPT) experiment. We take the best-fit value of the isotropic rotation angle from Planck data as our fiducial input. We project that 11 module-year (modyr) of observations will yield an improved detection sensitivity with a significance $\sim 5\sigma$, given a calibration precision of $0.1^{\circ }$ in the polarization angle. We also forecast AliCPT's sensitivity to the amplitude of a scale invariant spectrum of the anisotropic polarization rotation field. With $50$~modyr of observations, the large-aperture configuration is expected to reach ${\sigma }_{A_{\mathrm{CB}}}\sim 10^{-2}$, offering a sixfold improvement over the small-aperture design and enabling competitive tests of spatial fluctuations in the dark energy field.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2026)·1 citation
34. 34*

    The size of the quark-gluon plasma in ultracentral collisions: impact of initial density fluctuations on the average transverse momentum

    Fabian Zhou🇩🇪 · Giuliano Giacalone🇨🇭 · Jean-Yves Ollitrault🇫🇷

    Recent experiments have shown that the mean transverse momentum $⟨p_T⟩$ of outgoing particles increases as a function of the particle multiplicity in ultracentral nucleus-nucleus collisions at collider energies. This increase was originally predicted on the basis of simulations where the multiplicity increase occurred at constant volume, so that it implied a larger density and temperature. However, recent state-of-the-art simulations have shown that, for some models of initial condition, the volume may vary with the multiplicity in ultracentral collisions. We elucidate this effect by analytically relating the variation of the volume to the radial distribution of the one- and two-point functions of the fluctuating density field. We show that the volume variation is small if the total entropy of the ultracentral collisions scales with the mass number of the colliding isotopes. We argue that probing detailed transverse distributions of initial-state fluctuations through the ultracentral $⟨p_T⟩$ has nontrivial implications for models of nuclear structure and of the pre-equilibrium stages.

    ↳ nucl-thhep-phnucl-exPRC(2026)·4 citations
35. 35*

    Addressing the DESI DR2 Phantom-Crossing Anomaly and Enhanced $H_0$ Tension with Reconstructed Scalar-Tensor Gravity

    Dimitrios Efstratiou🇬🇷 · Evangelos Achilleas Paraskevas🇬🇷 · Leandros Perivolaropoulos🇬🇷

    Recent cosmological data, including DESI DR2, highlight significant tensions within the $\Lambda$CDM paradigm. When analyzed in the context of General Relativity (GR), the latest DESI data favor a dynamical dark energy (DDE) equation of state, $w(z)$, that crosses the phantom divide line $w=-1$. However, this framework prefers a lower Hubble constant, $H_0$, than Planck 2018, thereby worsening the tension with local measurements. This phantom crossing is a key feature that cannot be achieved by minimally coupled scalar fields (quintessence) within GR. This suggests the need for a new degree of freedom that can simultaneously: (A) increase the best-fit value of $H_0$ in the context of the DESI DR2 data, and (B) allow the crossing of the $w=-1$ line within a new theoretical approach. We argue that both of these goals may be achieved in the context of Modified Gravity (MG), and in particular, Scalar-Tensor (ST) theories, where phantom crossing is a natural and viable feature. We demonstrate these facts by analyzing a joint dataset including DESI DR2, Pantheon+, CMB, and growth-rate (RSD) data in the context of simple parametrizations for the effective gravitational constant, ${\mu }_G(z)\equiv G_{eff}/G_N$, and the DDE equation of state, $w(z)$. This MG framework significantly alleviates the tension, leading to a higher inferred value of $H_0=70.6\pm 1.4{\text{km s}}^{-1}{\text{Mpc}}^{-1}$. We also present a systematic, data-driven reconstruction of the required underlying ST Lagrangian and provide simple, generic analytical expressions for both the non-minimal coupling $F(\Phi )=1+\xi {\Phi }^2{e}^{n\Phi }$ and the scalar potential $U(\Phi )=U_0+a{e}^{b{\Phi }^2}$, which well-describe the reconstructed functions.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2026)·18 citations
36. 36*

    Large-Scale Structure Probes of the Post-Inflationary Axiverse

    Marco Gorghetto🇩🇪 · Sokratis Trifinopoulos🇨🇭 · Georgios Valogiannis🇺🇸

    We study the cosmology of axions in the post-inflationary scenario, where random initial conditions and the ensuing string-domain-wall network generate an isocurvature power spectrum. Axions radiated from strings behave as warm, wave-like dark matter: when they constitute the full dark matter abundance, free streaming sets the strongest bounds on their mass. For subdominant fractions, despite being warm, they still lead to an overall enhancement of structure growth in the dominant component, seeded by the axion white-noise fluctuations. We search for this effect using the ultraviolet luminosity function (UVLF) of galaxies at $z=4$-$10$, probing $k\simeq 0.5$-$10{\mathrm{Mpc}}^{-1}$. Combining the UVLF analysis with Lyman-$\alpha$ and CMB data yields the leading cosmological limits on post-inflationary axion dark matter, sensitive to tiny fractions for $m_a\lesssim 10^{-21}\mathrm{eV}$. As a byproduct, we obtain new constraints on generic white-noise power spectra from the UVLF. These results apply broadly to scenarios that generate similar isocurvature perturbations, linking early-universe field dynamics to high-redshift structure formation.

    ↳ astro-ph.COhep-phJCAP(2026)·11 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.