HEP Phenomenology·hep-ph

Mon·Jun 29, 2026Monday·June 29, 2026

41 papers—25 primary·16 cross-listed

01
Machine learning fully hadronic events with spectral functions
Mohammad Mahdi Altakach🇫🇷 · Hadi Hassan🇯🇵 · Sabine Kraml🇫🇷 · Kazuki Sakurai🇵🇱 · Haitham Zaraket🇱🇧
Characterising fully hadronic events is a difficult task at hadron colliders. Signal jets from the hard process are mingled with an arbitrary number of ISR and FSR jets, leading to a large combinatorial background. This also poses a challenge for machine-learning analyses, where the number of input features is fixed while the jet multiplicity fluctuates from event to event due to QCD radiation. In this work, we explore the use of the two-point correlation spectral function as an input feature for machine-learning analyses of such events. The spectral function maps the transverse-momentum data of an event into a one-dimensional function of the angular distance, encoding the event information modulo collider isometries and jet permutations, and is defined independently of the jet multiplicity. As a concrete benchmark we apply the method to discriminate gluino-pair production followed by $g ~ \to t t ˉ χ ~_{1}^{0}$ against the fully hadronic $t t ˉ$ background. With $139 fb^{- 1}$ of $s = 13$ TeV $pp$ collision data, a dense neural network supplied with spectral-function features improves the expected reach in gluino-mass by roughly 150 GeV relative to a recent ATLAS analysis, and by roughly 250 GeV relative to the same network trained on jet kinematics alone.
hep-phhep-ex0 citations
02
Collider Probes of Dark Energy Microphysics
Chaitanya Bashyam🇺🇸 · Alfredo Gurrola🇺🇸 · Andres Florez🇨🇴 · Cristian Rodriguez🇨🇴
The physical origin of dark energy remains one of the most profound open questions in modern physics. Although cosmological observations tightly constrain the equation of state parameter $w$ , this information alone does not reveal the underlying microphysics, as many distinct theoretical models can reproduce the same expansion history. A key discriminator among these models is the sound speed of dark energy perturbations, yet this quantity remains largely unconstrained by current astrophysical observations. In this work, we propose a fundamentally new approach: using collider measurements of beyond-the-Standard-Model (BSM) mediator resonances as a probe of dark energy microphysics. We construct a unified effective-field-theory framework in which a dynamical dark energy scalar is coupled, through symmetry-motivated derivative interactions, to a pseudoscalar mediator in the 2HDM+ $a$ model. These interactions naturally induce invisible decays and modify the propagation of the BSM mediator in a dark energy background, leading to measurable distortions of resonance properties at colliders such as the LHC. We show that the decay widths, branching ratios, and kinematic structure of the mediator resonance become sensitive to the propagation properties of dark energy fluctuations, in particular the sound speed. As a result, collider observables provide a direct and complementary handle on dark energy microphysics, with the potential to distinguish between models that are otherwise indistinguishable through cosmology alone. Our results establish a new paradigm in which high-energy collider experiments can probe the physics of cosmic acceleration, revealing a connection between the smallest and largest scales in nature and opening a novel experimental pathway to uncover the fundamental origin of dark energy.
hep-phastro-ph.COgr-qchep-ex0 citations
03
The one-point charge correlator in deep inelastic scattering
Haotian Cao🇺🇸 · Frank Petriello🇺🇸
In this work, we propose a novel definition of the one-point charge correlator (QC) adapted to the Breit frame in deep-inelastic scattering (DIS). We demonstrate that this observable is infrared and collinear (IRC) safe, ensuring its perturbative calculability. Utilizing soft-collinear effective theory (SCET), we systematically analyze the QC in both the forward and back-to-back limits. In the forward limit, we introduce the nucleon charge correlator as a novel non-perturbative object that encodes the multi-dimensional microscopic structure of the nucleon. In the back-to-back limit, the QC establishes a direct correspondence with transverse momentum-dependent distributions (TMDs), enabling its description within the standard TMD factorization formalism. The singular distributions are derived within SCET and are verified by the full QCD calculations up to $O (α_{s}^{2})$ . The corresponding collinear logarithms are resummed to all orders with the accuracy of NLL ( $O (α_{s}^{n} L^{n - 1})$ ), while the transverse momentum-dependent logarithms are resummed to all orders with the accuracy of $N^{3}$ LL for the unpolarized distribution and N $^{2}$ LL for the Sivers asymmetry.
hep-phPRD(2026)·2 citations
04
Light and heavy meson production in small collision systems
Ivan Vitev🇺🇸
Recent results from the LHC on oxygen-oxygen (O-O) and neon-neon (Ne-Ne) collisions open a new window for investigating the interplay of cold nuclear matter (CNM) and quark-gluon plasma (QGP) effects in small collision systems. Building upon recent theoretical work on particle production dynamics in heavy-ion reactions, we present an updated study of light and heavy hadron modification relative to the proton-proton baseline in these systems for selected centralities. Our analysis combines perturbative QCD and hydrodynamic simulations to quantify initial-state effect, collisional energy loss, and medium-induced radiative corrections. We give theoretical predictions at both midrapidity and forward rapidity that can be confronted with ALICE, ATLAS, CMS, and LHCb measurements. Through comparison to the available data, we discuss the relative importance of CNM and QGP effects in O-O and Ne-Ne systems and the role of the heavy quark mass. Our analysis aims to clarify the onset of collective and deconfined behavior in small systems and to provide new insights into the transport properties of matter. We further argue that investigation of other observable such as energy correlators and quarkonia can lead to a more complete picture of QGP formation in these collisions.
hep-ph0 citations
05
Nature of the newly found $Ω (2109)$
Taísa Veloso🇧🇷 · K. P. Khemchandani🇧🇷 · A. Martinez Torres🇧🇷 · H. Nagahiro🇯🇵 · A. Hosaka🇯🇵
We present model calculations to reveal the nature of the newly found $Ω^{-} (2109)$ by the BESIII Collaboration, and show that the state has a strong correlation with the $K ˉ^{*} (892) Ξ$ system. Our study is based on solving scattering equations in a coupled channel approach, which involves $K^{-} Ξ^{0}$ , $K ˉ^{0} Ξ^{-}$ , $K^{*-} Ξ^{0}$ , and $K ˉ^{* 0} Ξ^{-}$ . We obtain the lowest order amplitudes for different spin and isospin cases and find that an isoscalar state with spin-parity $1/ 2^{-}$ is generated with precisely the same mass as $Ω^{-} (2109)$ . We do not find any state with total spin 3/2, nor do we find any state in the isovector sector. We determine correlation functions to encourage such an experimental study and confirm the nature of $Ω^{-} (2109)$ .
hep-ph1 citation
06
Radiative Corrections in Bound States: Recent Results
Andrzej Czarnecki🇨🇦 · Artem O. Davydov🇨🇦
Two recent studies of radiative corrections to bound state properties are discussed. The change of the decay rate of a muon bound to a light nucleus has been calculated for several light nuclei $4 \leq Z \leq 9$ with high precision, resolving a long-standing discrepancy between analytical and numerical results for oxygen ( $Z = 8$ ). The decay of parapositronium into three photons has been calculated including effects of the $Z$ boson. The resulting rate is many orders of magnitude smaller than previously estimated.
hep-ph0 citations
07
$t t ˉ$ production as a window to invisible new physics
Rodrigo Capucha🇵🇹 · João Lopes🇵🇹 · João Bravo Martins🇵🇹 · António Onofre🇵🇹 · Rui Santos🇵🇹
We present a phenomenological study where we probe the sensitivity to invisible dark matter (DM) mediators produced in association with a $t t ˉ$ pair at the Large Hadron Collider (LHC). Building on previous work focused on scalar mediators, we extend the analysis to include spin-1 mediators, $Y_{1}$ , with both vector and axial-vector couplings to top quarks. The mediator mass is fixed to 5 GeV. Signal samples of $pp \to t t ˉ Y_{i}$ ( $i = 0, 1$ ) are generated using a MadGraph5_aMC@NLO simplified DM model. Only dileptonic final states of the $t t ˉ$ system are considered, and the reconstruction is performed through a kinematic fit without explicitly reconstructing the invisible mediator. All relevant Standard Model backgrounds are included. We consider several exclusion scenarios to assess the sensitivity to the presence of a spin-1 mediator, as well as the ability to distinguish a pure vector or axial-vector mediator from alternative hypotheses with different spin and CP properties. We find that the analysis is sensitive to light spin-1 mediators and that CP-sensitive angular observables provide discrimination power between vector, axial-vector, scalar and pseudoscalar scenarios. These results highlight the potential of $t t ˉ$ final states not only to search for invisible particles, but also to characterize their spin and parity properties in case of discovery.
hep-phhep-ex0 citations
08
From the quark parton model to QCD
Davison E. Soper🇺🇸
The quark parton model grew out of deeply inelastic scattering experiments. The parton model developed into a full theory, quantum chromodynamics, QCD. This article explains some of the physics issues encountered in connecting the parton model and QCD.
hep-phnucl-th2 citations
09
HydroGrav: Precise hydrodynamics and gravitational waves for cosmological phase transitions
Flynn Linton🇦🇺 · William Searle🇦🇺 · Xiao Wang🇦🇺 · Csaba Balázs🇦🇺
We present HydroGrav, a C++ code used to construct self-similar fluid profiles, using the exact equation of state determined directly from the effective potential, for any particle physics model capable of producing a first-order electroweak phase transition. HydroGrav also supports the bag and $μν$ (or improved bag) equations of state and includes an implementation of the sound shell model for computing the corresponding gravitational wave spectra. Using this framework, we compare the fluid profiles and gravitational wave spectra for the simplified (bag and $μν$ ) and exact equations of state for a $Z_{2}$ -symmetric extension of the Standard Model. Furthermore, we perform a scan across the parameter space of this model to identify regions where the simplified and exact equations of state differ in peak amplitude and spectral shape. Finally, we estimate the effect of using the exact equation of state on the signal-to-noise ratio across the parameter space, as measured by LISA after a 4-year mission.
hep-phastro-ph.CO1 citation
10
Bootstrapping two-loop six-gluon amplitudes in QCD
Sérgio Carrôlo🇩🇪 · Dmitry Chicherin🇫🇷 · Johannes M. Henn🇩🇪 · Qinglin Yang🇩🇪 · Yang Zhang🇨🇳
The maximally transcendental, or most complicated, terms of gauge-theory scattering amplitudes have long been singled out, following Lipatov and collaborators, as those parts of a QCD amplitude that most closely mirror maximally supersymmetric Yang--Mills theory. We report on a programme that turns this observation into a practical computational tool. We show that the rational prefactors multiplying the highest-weight special functions of planar QCD amplitudes are governed by four-dimensional leading singularities, which can be classified and evaluated using on-shell diagrams. The resulting prefactors are manifestly conformally invariant and admit compact spinor-helicity expressions that hold for arbitrary multiplicity. Combining this input with the recently established two-loop six-particle function space, we set up a symbol bootstrap and determine, for the first time, the maximal-weight symbol of the planar two-loop six-gluon amplitude in massless QCD, first for the $- - + + + +$ helicity configuration and subsequently for all MHV configurations. The answer is fixed uniquely by physical consistency conditions, requires a reduced alphabet of only $137$ symbol letters, and yields as a byproduct previously unknown two-loop triple-collinear and double-soft splitting functions. We summarise the method and the results, and outline the directions they open up.
hep-phhep-th0 citations
11
Leptonic CP Conservation and the Quark CP Phase from Octonionic Flavor Structure
Bishnu Gupta Teli🇮🇳 · Tejinder P. Singh🇮🇳
One generation of standard-model fermions can be realized on the complexified octonions through the Clifford algebra $C l (6)$ ; the octonionic unification programme extends this to three generations, with generation transport implemented by $G_{2}$ automorphisms or by rotors built from the ladder operators. We prove a localization theorem for the CP-violating phases of this structure, using only the $C l (6)$ construction and the stated three-generation representatives, independently of the wider programme. For quarks, the first-to-second generation step is the occupation flip of one ladder mode, with the up and down species coupling to conjugate ladder directions; a conjugation theorem forces $A_{d} = A_{u}^{*}$ for every real transport, and the most general rung-generated rotor yields the exact one-parameter law $ϕ_{12} = - 2 χ$ : the $(1, 2)$ transport phase is twice one Yukawa orientation angle. The programme's geometric rotor sits exactly at the quadrature-balanced point $∣ ϕ_{12} ∣ = π /2$ ; the companion analysis reproduces the Cabibbo \emph{magnitude} $∣ V_{u s} ∣$ with a single real tilt, leaving the rung near quadrature, but it does not extract a CKM CP phase, so the quark Dirac phase is fixed only once the underlying Yukawa orientation is computed. For leptons we prove a reality theorem: every charged-lepton and every neutrino transport amplitude is exactly real for every $G_{2}$ automorphism and every rotor that does not mix the identity line $C \cdot 1$ with the lepton--flavor plane $span (e_{7}, e_{5}, e_{2})$ a class that contains the entire quark-rung family--and identity--flavor mixing across that plane is the unique possible source of a leptonic phase. [Truncated]
hep-ph5 citations
12
Prospects for probing neutral vector-like leptons via pair production at muon collider
Chong-Xing Yue🇨🇳 · Mei-Shu-Yu Wang🇨🇳 · Xin-Yang Li🇨🇳 · Si-Yu Zhang🇨🇳
Vector-like leptons (VLLs) are well-motivated candidates for physics beyond the Standard Model. We investigate the sensitivity of the $6$ TeV muon collider to the neutral doublet VLL (denoted as $N$ ) via its pair production within a general VLL framework. Taking vector-like muon as a case study, we study the subsequent decay $N \to W^{+} μ$ and analyze two representative signals, namely $4 j 2 μ$ and $2 ℓ 2 μ E /$ , arising from the hadronic and leptonic decays of the $W$ boson, respectively. The signal and background events are simulated within a complete Monte Carlo framework, and a cut-based analysis is performed at the $6$ TeV muon collider with an integrated luminosity $L = 4$ ab $^{- 1}$ and beam polarizations $(P_{μ^{+}}, P_{μ^{-}}) = (- 1, 1)$ . We consider VLL masses in the range of $1300 - 3000$ GeV and evaluate the corresponding search sensitivity. Our results show that the future $6$ TeV muon collider can effectively probe neutral doublet VLLs through the $4 j 2 μ$ and $2 ℓ 2 μ E /$ signals, with statistical significances exceeding $5 σ$ over a broad mass range. These results demonstrate that the future $6$ TeV muon collider has excellent potential to search neutral doublet VLLs.
hep-ph0 citations
13
Antideuteron production from beauty-hadron decays: a first phenomenological study
Marta Razza🇮🇹 · Nicolò Jacazio🇮🇹 · Francesca Bellini🇮🇹
Light antinuclei, such as antideuteron ( $d ˉ$ ) and antihelium ( $^{3} He$ , $^{4} He$ ), provide a link between collider physics and indirect Dark Matter searches. Despite extensive studies of antinucleus production in high-energy collisions, $d$ production from beauty-hadron decays remains experimentally unconstrained and has not yet been quantitatively predicted. In this work, we present the first phenomenological study of $d$ production from $Λ_{b}$ baryon and B $^{-}$ meson decays, providing the first estimates of the corresponding branching ratios. Beauty-hadron decays are simulated with PYTHIA using realistic input kinematics and three hadronization scenarios. Antideuteron formation is modelled through a quantum-mechanical coalescence approach based on an $d ˉ$ wave function derived from the Argonne $v_{18}$ nucleon-nucleon potential. Depending on the adopted hadronization model, we estimate inclusive branching ratios to be $(5.68 \pm 0.02) \times 1 0^{- 4} < B R (Λ_{b} \to d + X) < (1.408 \pm 0.004) \times 1 0^{- 3}$ and $(7.4 \pm 0.3) \times 1 0^{- 6} < B R (B^{-} \to d + X < (4.34 \pm 0.07) \times 1 0^{- 5}$ . The predicted rapidity- and transverse-momentum-differential yields populate the kinematic region where $d$ can be identified by the ALICE experiment, motivating dedicated searches for these decay channels. These results provide a quantitative benchmark for $d$ production from beauty-hadron decays and establish a phenomenological framework to support future experimental searches, with potential implications beyond collider physics.
hep-ph0 citations
14
Quantum Correlations in the Decay of $B^{0}$ meson and Entanglement Entropy
Divya Sharma🇺🇸 · Vaibhav Rawoot🇮🇳 · Sudip Kumar Haldar🇮🇳
We present a phenomenological study of quantum correlations in the decay of $B^{0}$ mesons into a system of two vector mesons. The decay of the $B^{0}$ meson into two vector mesons constitutes a bipartite system of two qutrits. The entanglement entropy is used as a measure of quantum correlations in the system of decaying particles. We study the variation of the Rényi entropy with Rényi order ( $α$ ) for the decay channels $B_{s}^{0} \to ϕ ϕ$ , $B_{d}^{0} \to J / ψ K^{*} (892)^{0}$ , $B_{d}^{0} \to ϕ K^{*} (892)^{0}$ and $B_{s}^{0} \to J / ψ ϕ$ and discuss the significance of entanglement entropy at different Rényi order regimes. The LHCb, ATLAS and Belle collaborations experimental measurements of complex polarization amplitudes and relative phases are used as input for our analysis. A comparison of entanglement entropy for all the $B^{0}$ meson decay processes, with both vanishing and non-vanishing phases, reveals a strong phase dependence of the entropy. We further present the results of Hartley entropy (Max-Entropy), von Neumann entropy, collision entropy, and min-entropy, each corresponding to different values and limits of the Rényi order. The comparison between the branching fractions of the decay processes and the von Neumann entropy shows a connection between entanglement and decay dynamics, indicating the role of weak and strong interaction in generating quantum entanglement. In addition, we evaluate several other entanglement measures, including linear entropy, I-concurrence, tangle, negativity, logarithmic negativity, Schmidt coefficients, and Schmidt rank for different $B^{0}$ meson decay processes. Our study demonstrates that entanglement measures provide useful insights into the underlying decay dynamics and may serve as important tools for understanding quantum correlations in high-energy particle physics processes.
hep-phhep-exhep-thquant-ph0 citations
15
Analysis of the hidden-charm pentaquark candidates in the $J / ψ Ξ^{*}$ mass spectrum via the QCD sum rules
Zhi-Gang Wang🇨🇳
In this work, we explore the diquark-diquark-antiquark type decuplet hidden-charm pentaquark states with the symbolic valence structure $q ssc c ˉ$ via the QCD sum rules extensively, and achieve the spectroscopy of the lowest decuplet $q ssc c ˉ$ pentaquark states with the quantum numbers $I J^{P} = \frac{1}{2} \frac{1}{2}^{-}$ , $\frac{1}{2} \frac{3}{2}^{-}$ and $\frac{1}{2} \frac{5}{2}^{-}$ , and suggest to explore these exotic states in the exclusive processes $Ξ_{b}^{'0} \to P_{css}^{0} ϕ \to J / ψ Ξ^{* 0} ϕ$ and $Ω_{b}^{-} \to P_{css}^{-} K ˉ^{0} \to J / ψ Ξ^{*-} K ˉ^{0}$ . As a byproduct, we can re-testify classifications of the light baryons by investigating the hidden-charm pentaquark decays.
hep-ph5 citations
16
Dense and Cold Magnetized Quark Matter: A Review of Magnetic-Field-Independent Regularization and the Medium Separation Scheme
Francisco X. Azeredo🇧🇷 · Dyana C. Duarte🇧🇷 · Ricardo L. S. Farias🇧🇷 · Bruno S. Lopes🇧🇷 · João A. R. S. Prado🇧🇷 · William R. Tavares🇧🇷
We present a comprehensive review of regularization schemes for magnetized dense quark matter within effective models of quantum chromodynamics, focusing on the Magnetic-Field-Independent Regularization (MFIR) and the Medium Separation Scheme (MSS) at finite chemical potential and magnetic field. In nonrenormalizable frameworks such as the Nambu-Jona-Lasinio model, the treatment of ultraviolet divergences is crucial, particularly in magnetized and dense environments where conventional regularization procedures may introduce unphysical artifacts. We show that MFIR consistently isolates divergent vacuum contributions from finite magnetic-field-dependent terms, while MSS extends this separation to the medium sector, ensuring that only vacuum quantities are regularized. Within this unified framework, we analyze the thermodynamics of cold and dense quark matter, including color-superconducting phases, and demonstrate that the superconducting gap remains finite at large chemical potentials, even in the presence of strong magnetic fields. In contrast to results obtained with traditional regularization schemes, we find no evidence for a transition to a normal phase at zero temperature, highlighting the importance of a proper separation between vacuum and medium contributions. These results eliminate spurious oscillations and other nonphysical artifacts, leading to a more robust and physically consistent description of strongly interacting matter under extreme conditions relevant to compact stars and heavy-ion collisions.
hep-phhep-lathep-thnucl-th1 citation
17
Scattering Amplitudes and Resonant Processes in QED with Chiral Chemical Potential and Chiral Magnetic Conductivity
Jonathan D. Kroth🇺🇸 · Kirill Tuchin🇺🇸
The QED scattering amplitude in a chiral medium characterized by a constant chiral chemical potential $μ_{5}$ and chiral magnetic conductivity $b_{0}$ is analyzed. We show the emergence of the resonant behavior in $1 \to 2$ , $2 \to 2$ , and $2 \to 3$ processes. We compute the rates of paradigm $1 \to 2$ processes that determine the widths of quasi-stationary fermion and photon states in the medium. We elucidate the origin of these resonances, the conditions of their emergence, and the physical principles of their regularization.
hep-phhep-th1 citation
18
Probing the neutrino chemical potential with cosmological observations
Pietro Ghedini🇪🇸 · Riccardo Impavido🇮🇹 · Stefano Gariazzo🇪🇸 · Olga Mena🇪🇸 · Deng Wang🇪🇸
The electron neutrino degeneracy parameter, $ξ_{ν_{e}} = μ_{ν_{e}} / T$ , is tightly constrained by Big Bang Nucleosynthesis (BBN), while the degeneracy parameters of the other neutrino species, $ξ_{ν_{x}}$ , remain weakly constrained by cosmological observations alone. In this manuscript we shall compute up-to-date bounds on $ξ_{ν_{e}}$ and $ξ_{ν_{x}}$ assuming that either they are constant free-parameters along the cosmic history or that they are redshift dependent quantities. In the latter case we employ a model-independent reconstruction approach based on the Piecewise Cubic Hermite Interpolating Polynomial (PCHIP) formalism with four nodes, located at $z ≃$ 10, 100, 1000 and $1 0^{8}$ . We shall also consider two scenarios for neutrinos, specifically three degenerate neutrinos ( $ξ_{ν_{e}}$ = $ξ_{ν_{x}}$ ) and the case in which we actually differentiate between $ξ_{ν_{e}}$ and $ξ_{ν_{x}}$ . We perform a cosmological analysis combining CMB data from Planck, SPT, and ACT with BAO measurements from DESI, showing the impact of including BBN observables from either EMPRESS results, which allow for a non-zero chemical potential, or from LBT observations, compatible with the standard $ξ_{ν}$ = 0 prediction. We explicitly show that the BBN data, via the change in neutron-to-proton interconversion rates, mostly constrain $ξ_{ν_{e}}$ , parameter for which we observe a preferred non-zero positive value at $95%$ C.L. in the non-degenerate neutrino case at the BBN period. Since the Hubble constant is correlated with $ξ_{ν}$ , through $N_{eff}$ , a larger value of $H_{0}$ is allowed within these models, making them really interesting scenarios where to test non-standard physics models.
hep-phastro-ph.COPhys.Dark Univ.(2026)·0 citations
19
Pion and Kaon PDFs via Infrared-Safe Evolution augmented by $J / ψ$ Data Constraints
Yanbing Cai🇨🇳 · Chengdong Han🇨🇳 · Xurong Chen🇨🇳
Probing the partonic structure of the pion and the kaon provides essential insights into the non-perturbative dynamics of QCD, yet their parton distribution functions (PDFs) remain poorly constrained due to the scarcity of high-precision experimental data, especially for the gluon distributions. We present an improved determination of pion and kaon PDFs within the dynamical parton model combined with the maximum entropy method (MEM) framework. Our analysis features two key advancements: firstly, we employ an infrared-safe QCD evolution scheme, allowing the evolution to be reliably extended down to very low $Q^{2}$ , approaching the hadronic scale; secondly, we incorporate pion- and kaon-induced $J / ψ$ hadroproduction data as crucial constraints in the global fit. We find that our approach yields a good description of the available Drell-Yan data, deep-inelastic scattering structure functions ( $F_{2}$ ), and $J / ψ$ production across various energies and targets. The results provide significantly improved constraints on the gluon distributions at moderate and large $x$ in both the pion and the kaon, offering a more complete picture of their internal structure.
hep-ph0 citations
20
Real poles with opposite-sign residues in the non-perturbative quark propagator
R. Alkofer🇦🇹 · M.N. Ferreira🇧🇷 · A.S. Miramontes🇪🇸 · J.M. Morgado🇪🇸 · J. Papavassiliou🇪🇸
We investigate the analytic structure of the quark propagator in the Landau gauge by dynamically coupling the standard gap equation to the non-perturbative quark-gluon vertex. Employing the full vertex basis, we demonstrate that for sub-GeV time-like momenta, the proper inclusion of the underlying dynamics leads to a pair of real poles with opposite-sign residues. In particular, in stark contradistinction to the results obtained in widely used approximations, we see no sign of complex conjugate poles. This distinctive analytic structure evades conceptual shortcomings frequently associated with complex conjugate poles while remaining fully compatible with the aspects of color confinement related to positivity violation. Crucially, this novel behavior is governed by a dominant triplet of vertex form factors: the tree-level component, the anomalous chromomagnetic moment, and a component we label as "spin-momentum curvature". By gradually tuning the individual strengths of these components, we demonstrate that while they contribute in distinct ways to the quark propagator, their joint action is vital for stabilizing the system. Together, they place the low-lying poles onto the real axis while producing a robust constituent quark mass of $350$ MeV.
hep-phhep-lathep-thPLB(2026)·2 citations
21
Neural-Network extraction of TMDs with SIDIS data
Matteo Cerutti🇫🇷
A first global analysis of unpolarized Transverse-Momentum-Dependent (TMD) distributions based on a neural-network (NN) parametrization is presented. Drell-Yan (DY) and semi-inclusive deep inelastic scattering (SIDIS) data are simultaneously included at next-to-next-to-next-to-leading logarithmic (N $^{3}$ LL) accuracy. The results indicate that the inclusion of SIDIS data leads to broader unpolarized TMD PDFs compared to a DY-only NN extraction. The associated uncertainties are reduced with respect to the DY-only case, while remaining larger than the ones obtained using traditional models. These results demonstrate the potential of flexible NN parametrizations in reducing model dependence and provide guidance for future high-precision measurements at Jefferson Lab and the Electron-Ion Collider.
hep-phhep-exhep-lat1 citation
22
Neutrino oscillation data and a pseudo-Dirac heavy neutral lepton
Jan Hajer🇵🇹
Symmetry-protected seesaw models can accommodate light-neutrino oscillation data while keeping heavy neutral leptons (HNLs) within collider reach. In these models, the smallness of the light-neutrino masses is protected by an approximate lepton number (LN)-like symmetry that is broken only by small parameters. We study the minimal scenario in which the new states form one pseudo-Dirac HNL pair. The exact LN-conserving Dirac limit is diagonalised without expanding in the active-sterile mixing, and the small LN-violating entries are then included perturbatively. This yields a symmetry-protected flavour reconstruction of the active-heavy interaction matrix. The rank-two light-neutrino mass matrix fixes the normalised active-flavour direction, while the remaining high-energy information is a single complex light-heavy amplitude whose phase defines a CP-odd light-heavy invariant. For the normalised leading active-heavy interaction weights, this amplitude and the heavy-sector rotation cancel, leaving an ellipse in the flavour simplex determined by light-neutrino oscillation data and the Majorana phase. We also identify how the linear LN-violating terms enter coherent heavy-neutrino oscillations and the neutrinoless double beta effective mass.
hep-ph0 citations
23
Revealing precision bounds on neutrino oscillation parameters with quantum estimation theory
Jihong Huang🇨🇳 · Tommy Ohlsson🇸🇪 · Sampsa Vihonen🇸🇪 · Shun Zhou🇨🇳
Quantum estimation theory provides ultimate precision bounds on parameter estimation, independent of experimental setups. In this article, we apply this theoretical framework to neutrino oscillations, aiming to clarify some subtle issues and reveal the maximum achievable precision of oscillation parameters. First, taking the example of two-flavor oscillations, we clarify how the quantum Fisher information (QFI) depends on the choice of bases when the basis transformation itself involves the parameters in question. Then, for three-flavor oscillations, we compute the QFI matrix for electron and muon neutrino states in the flavor basis and derive analytical expressions and numerical results for both diagonal and off-diagonal elements. The implications of off-diagonal correlations for multiparameter estimation are discussed, and the quantum Cramér-Rao bounds on the precision of oscillation parameters for typical reactor and long-baseline accelerator neutrino experiments are obtained. Our results establish a theoretical benchmark for the ultimate precision achievable in future neutrino oscillation experiments.
hep-phquant-ph3 citations
24
Particle Production from Inhomogeneities: the off-shell side of gravitational waves
Michele Redi🇮🇹 · Andrea Tesi🇮🇹
We continue the study of particle production from gravitational inhomogeneities in the early Universe. Focusing on sources active on sub-horizon scales, we derive general expressions relating particle production to the unequal-time two-point function of the stress-energy tensor sourcing scalar, vector and tensor metric perturbations. The resulting particle yield probes the time-like support of this correlator, and in the tensor case the same object controls gravitational wave emission when evaluated on the light-like support. This establishes a phenomenological link between dark matter production and gravitational wave signals, allowing the dark matter mass to be related to the amplitude of the stochastic gravitational wave background. Our results show that, on sub-horizon scales, particle production from inhomogeneous metric backgrounds practically reduces to gravitational scattering. This directly connects the formalism to gravitational freeze-in from the Standard Model thermal bath, while extending it to non-thermal and out of equilibrium sources. We apply the formalism to first order phase transitions and discuss the associated production from scalar and tensor perturbations. The mechanism can efficiently populate gravitationally coupled dark sectors, especially when the perturbations are generated shortly after inflation.
hep-phastro-ph.COgr-qchep-th3 citations
25
Near-threshold scattering of proton and Omega baryon and possible bound states
Yu-Jie Feng🇨🇳 · Qian Wang🇨🇳 · Qiang Zhao🇨🇳
We study the near-threshold scattering and bound-state structure of the $N Ω$ system by solving the Lippmann-Schwinger (L-S) equation within the framework of the meson exchange model and the Pomeron exchange model. The numerical results indicate that after incorporating the Pomeron exchange mechanism, the observables of the $^{5} S_{2}$ channel, such as the binding energy, scattering length, and effective range, agree better with the experimental measurements. In addition, The Pomeron exchange can provide an extra attractive interaction to make the hadronic state more compact. We also predict the scattering behavior of the $^{3} S_{1}$ channel and confirm that a weak quasi-bound state exists in this channel. Future experimental measurements on the $^{3} S_{1}$ channel will provide an important criterion for verifying the dynamic role played by the Pomeron exchange mechanism within the $N Ω$ system.
hep-ph0 citations
26
The crust of dark-matter admixed neutron stars: bulk properties and torsional oscillations
Jiayi Zhang🇺🇸 · Hector O. Silva🇺🇸
We study how dark matter (DM) impacts the crust and the spectrum of torsional crust oscillations of dark-matter-admixed neutron stars (DANSs). We construct two-fluid equilibrium solutions wherein baryonic and DM interact gravitationally only, adopting a unified nuclear equation of state for the former and a fermionic equation of state with repulsive self-interaction for the latter. At fixed total gravitational mass and DM mass fraction, we find that DM reduces the crust thickness in comparison to pure baryonic-matter neutron stars (NSs). The thinning of the crust is negligible when most of the DM distribution extends beyond the star's baryonic surface. However, the crust thickness can decrease by as much as 12% when the DM distribution is within the star's baryonic surface, i.e., when the star has a "dark core." We support these results by deriving approximate analytical formulas for the crust thickness that agree with our numerical calculations at the sub-percent level in best case scenarios. Next, we derive the equation that describes crustal torsional modes of DANSs in the relativistic Cowling approximation. We find that the oscillation frequencies are in general higher than those of a comparable pure baryonic-matter NS, with the largest frequency shifts happening in the same parameter space where the crust thickness decreases the most. Moreover, we study the degeneracy between DM and baryonic-crustal microphysics effects on these modes. As an example, we study electron screening, which softens the crust's shear modulus, thus decreasing the frequencies. We find that the degeneracy between the competing effects of DM and electron screening can be broken in some regions of the parameter space we explored. Should they be measured, our results suggest that torsional oscillations could be used to infer the existence of a DM core within massive NSs. (Abridged)
↳ gr-qcastro-ph.HEhep-phnucl-th0 citations
27
Modelling Dissipative Dynamics of r-mode Instability in Hybrid Stars
Khushbu Zala · Sreemoyee Sarkar🇮🇳
Compact star cores reach extreme densities and may contain exotic dense-matter phases. Information about the exotic interiors of rapidly rotating pulsars can be inferred from r-mode oscillations, whose stability is governed by viscous dissipation. In this work, we model a compact star containing a possible mixed phase of hadronic and quark matter and employ a hybrid statistical framework based on Bayesian inference to infer the dissipation time scales associated with the hybrid phase. Using low-mass X-ray binaries (LMXB) timing observations together with mass-radius constraints from the Neutron Star Interior Composition Explorer (NICER) mission, we estimate the shear and bulk viscosity contributions to r-mode damping for a hybrid star of two layers. Our inference yields shear and bulk viscous dissipation time scales of $τ_{s} = (4.9 9_{- 0.52}^{+ 0.49}) \times 1 0^{8} T^{\frac{5}{3}}$ s and $τ_{B} = (2.15 0_{- 0.60}^{+ 1.23}) \times 1 0^{19} (T^{4} 1 0^{- 12} + T^{2} 1 0^{- 6})^{- 1} Ω^{- 2}$ s respectively. The timescales thus obtained can be implemented to obtain the minima of the star's rotation frequency at $Ω = 451.87$ Hz at temperature $T = 0.259$ MeV for a hybrid star of mass $1.5$ $M_{⊙}$ and $Ω = 517.47$ Hz at $T = 0.234$ MeV for $M = 1.75 M_{⊙}$ . We find that the instability window obtained through the inference framework effectively explains the observed stability of millisecond pulsars in both the radio and LMXB populations, particularly for XTE J0929-314 and XTE J1807-294, J0437-4715, J2124-3358, respectively. These results demonstrate that Bayesian inference combined with r-mode phenomenology provides a powerful and observationally consistent framework for constraining the transport properties of dense hybrid matter.
↳ astro-ph.HEhep-phnucl-th0 citations
28
Soft QED as Open Quantum System: Infrared Cancellation and Soft-Shell Coarse Graining
Soo-Jong Rey🇰🇷
I formulate unresolved soft-photon sector of QED as open quantum system. Resolved charged particles and hard photons form the system, unresolved soft photons form the environment, and basic object is the reduced density matrix. A resolved outcome $f$ of multiple hard particles and photons has probability $P_{f} (i) = \sum_{n} ∣ ⟨ f, n ∣ S ∣ i, 0 ⟩ ∣^{2} = ⟨ i ∣ F_{f} ∣ i ⟩$ , with Kraus operators $K_{n} =_{soft} ⟨ n ∣ S ∣0 ⟩_{soft}$ and effect $F_{f} = \sum_{n} K_{n}^{†} Π_{f} K_{n}$ . The SK formulation places unresolved virtual and real terms in one doubled-contour expansion. At one loop they carry the same on-shell eikonal kernel with opposite signs. This elegantly organizes the QED probability: for the same observable, perturbative order, diagrams, and phase space, the OQS gives the same infrared-finite terms as the full-QED. The soft-photon evolution is a unitary coherent-state displacement driven by the scattering current. The equal-history identity of influence functional exactly normalizes this soft evolution; together with the soft-photon theorem it removes the IR divergent leading-soft factor from inclusive probability. I also derive explicit leading-soft QED realization of scale-parametrized Lindblad evolution on a fixed hard-branch space. Tracing an infinitesimal soft-photon shell produces diagonal jump operators whose entries are fixed by the corresponding eikonal emission amplitudes. The finite-shell map is a completely positive unital Schur channel and, in the sharp scale-invariant leading-soft regime, a dephasing semigroup of a completely-positive-divisible scale flow. The resulting logarithmic visibility slope and monotonic purity loss are off-diagonal predictions of the reduced-state description. The same controlled-displacement dilation gives the Sudakov probability, Poisson soft-photon multiplicities, and the bremsstrahlung number spectrum.
↳ hep-thcond-mat.stat-mechhep-phquant-ph4 citations
29
$SMaSH$ : Simplify Massive Spinor Helicity
Aakash Kumar · Arnab Rudra · Rahul Shaw
We present $SMaSH$ , a $Mathematica$ package to do spinor helicity computations in four spacetime dimensions $\href$ . It can handle massive spinor helicity computations with explicit little group indices which is a novel feature. It can also handle massless as well as off-shell spinor helicity variables. It is designed to compute perturbative computations; it comes with predefined three point amplitudes and propagators for any masses and spins (arXiv:1709.04891). It can implement the high energy limit over an expression, check the discrete $C, P, T$ transformations, compute contact terms and impose gauge invariance for any scattering process. We have shown the usage of such functions for computing gauge invariant Weinberg minimal amplitudes (arXiv:2506:12431, arXiv:2504:06343). The package can also generate both real and complex numerical kinematics for any $n$ -point scattering for arbitrary masses and energy scales by implementing the $RAMBO$ algorithm. It is also rich with basic spinor helicity manipulations like Schouten simplification, Clifford algebra manipulation, conversion between spinor helicity and Lorentz vectors, derivative w.r.t. spinors and their scalars, helicity scaling etc.
↳ hep-thhep-phphysics.comp-ph0 citations
30
Probing Two Dark Dimensions through Primordial Black Holes, Gravitational Waves, and Colliders
Waqas Ahmed🇨🇳 · George K. Leontaris🇬🇷
We study primordial-black-hole (PBH) dark matter in the two-dark-dimensions (2DD) framework, a six-dimensional brane-world scenario with two compact extra dimensions and a fundamental gravity scale of order $10 TeV$ . We calculate the evolution of higher-dimensional PBHs including the recently proposed quantum-gravitational memory-burden effect. For a memory exponent $p = 2$ , the evaporation rate is strongly suppressed, allowing PBHs with initial masses as small as $\sim 1 0^{- 3} g$ to survive until the present epoch. Consequently, PBHs can account for the observed dark matter over a mass range extending from $1 0^{- 3} g$ to $1 0^{21} g$ . We further compute the stochastic gravitational-wave background generated at second order by the primordial curvature perturbations responsible for PBH formation. We show that the conventional four-dimensional formalism for scalar-induced gravitational waves remains applicable throughout the mass range accessible to current and future gravitational wave experiments. The resulting signals can be probed by LISA, DECIGO, and pulsar timing arrays. Using Fisher forecasts, we find that these observations can constrain the PBH mass, dark-matter fraction, and width of the primordial curvature spectrum with high precision. The low fundamental gravity scale of the 2DD framework also permits the production of microscopic black holes at future high-energy colliders. Their decay signatures, together with gravitational-wave measurements, provide complementary tests of higher-dimensional gravity, the memory-burden mechanism, and primordial-black-hole dark matter.
↳ gr-qchep-phhep-th1 citation
31
UV artefacts in ultra-slow-roll models of inflation
Gerald Barnert🇬🇧 · Laura Iacconi🇬🇧 · Hooshyar Assadullahi🇬🇧 · Kazuya Koyama🇬🇧 · David Wands🇬🇧
Within single-field inflation, primordial black hole and scalar-induced gravitational wave production from enhanced primordial perturbations typically requires a transient non-attractor phase, such as ultra-slow roll. We investigate the physical consistency of modeling such scenarios through analytical Hubble-flow parametrisation. By reconstructing the underlying scalar field potential, we show that even slow transitions in the slow-roll parameters can hide sharp, localised spikes in higher-order derivatives of the potential at the transition from ultra-slow-roll to slow-roll. These are typically not found in analytic potentials. To evaluate the impact of these structures, we implement a UV-filtering procedure based on discrete Fourier transform to systematically suppress high frequency modes in field space in both classes of models. We find that the filter effectively removes sharp features in Hubble-flow-derived potentials. As a consequence, we show that UV-filtered models typically respect Wands duality invariance as the field evolves back from ultra-slow roll to slow roll. Beyond linear perturbation theory, the introduction of spurious UV effects might affect other observables, such as non-Gaussianity and loop contributions. Our results thereby question the robustness of simple analytical Hubble-flow parametrisation for modeling inflationary models with a transient non-attractor phase.
↳ astro-ph.COgr-qchep-phhep-th1 citation
32
The QCD energy-momentum tensor on the lattice: non-perturbative renormalization with $N_{f} = 3$
Matteo Bresciani🇮🇪 · Mattia Dalla Brida🇮🇹 · Leonardo Giusti🇮🇹 · Mitsuaki Hirasawa🇮🇹 · Michele Pepe🇮🇹 · Luca Virzì🇮🇹
We construct the traceless components of the energy-momentum tensor on the lattice for QCD with $N_{f} = 3$ flavours, such that their correlation functions satisfy the appropriate Ward identities in the continuum limit. To carry out this program, we define the theory on the lattice by the Wilson-plaquette and the $O (a)$ -improved Wilson actions for gluons and quarks respectively. The discretization of the space-time entails that (i) the irreducible nonet representation of the SO( $4$ ) group splits into a triplet and a sextet irreducible representations of the hypercubic group, and (ii) for each multiplet non-perturbative determinations of the the gluonic and fermionic renormalization constants are required. The bare gluonic components of the energy-momentum tensor are defined via the clover discretization of the field strength tensor, while the fermionic ones are discretized by appropriate combinations of symmetric covariant derivatives. Either for the triplet or the sextet representations, the two independent renormalization constants are then fixed non-perturbatively by imposing discretized versions of continuum Ward identities for one-point correlation functions in the presence of shifted boundary conditions and an imaginary chemical potential. The non-perturbative calculation is then carried out by Monte Carlo simulations, and the resulting renormalization constants are determined with a final accuracy of a few percent for values of the bare coupling constant squared in the range $0 \leq g_{0}^{2} \leq 0.96$ .
↳ hep-latastro-ph.COhep-phhep-th0 citations
33
The QCD phase diagram for three-flavor Möbius domain-wall fermions
Yu Zhang🇩🇪 · Yasumichi Aoki🇯🇵 · Jishnu Goswami🇩🇪 · Shoji Hashimoto🇯🇵 · Issaku Kanamori🇯🇵 · Takashi Kaneko🇯🇵 · Yoshifumi Nakamura🇯🇵
We investigate the phase transition of Quantum Chromodynamics (QCD) with three degenerate quark flavors at zero baryon chemical potential. Using Möbius domain-wall fermions as the lattice fermion formulation, we ensure excellent chiral symmetry preservation. Our simulations are performed at three different temporal lattice extents, $N_{t} = 6, 8, 12$ , with a fixed lattice spacing $a = 0.1361 (20)$ fm, corresponding to temperatures of 242(4), 181(3), and 121(2) MeV, respectively. We explore a range of quark masses and spatial volumes with aspect ratios $N_{s} / N_{t}$ spanning from 2 to 4. By analyzing the mass and volume dependencies of the plaquette, plaquette susceptibility, chiral condensate, chiral susceptibilities, and Binder cumulant, we identify the pseudocritical transition quark masses from our largest lattice volumes. For $N_{t} = 6$ , this is 184(10) MeV (determined from the plaquette susceptibility). For $N_{t} = 8$ and 12, the transition points vary slightly depending on whether the total or disconnected chiral susceptibility is used, yielding ranges of 36(1)-39.1(9) MeV and 3.5(3)-3.7(2) MeV, respectively, in the $MS$ scheme at a scale of $μ = 2$ GeV. The negligible volume dependence at $N_{t} = 6$ and 8, combined with finite-size scaling analysis at $N_{t} = 12$ revealing volume growth significantly weaker than expected for a first- or second-order phase transition, points to a continuous crossover at these specific quark mass points. Additionally, we study the effects of residual chiral symmetry breaking on the chiral condensate and chiral susceptibilities using two different values of $L_{s}$ .
↳ hep-lathep-phhep-thnucl-th0 citations
34
Mellin Moments of Pion and Kaon Unpolarized PDFs from Nonlocal Operators in Lattice QCD
Joshua Miller🇺🇸 · Joseph Torsiello🇺🇸 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Joseph Delmar🇺🇸
We present a first-principles lattice-QCD determination of Mellin moments of the unpolarized pion and kaon parton distribution functions using matrix elements of boosted mesons coupled to nonlocal operators containing a straight Wilson line. The calculation is performed on an $N_{f} = 2 + 1 + 1$ ensemble of maximally twisted-mass fermions with a clover term, with lattice volume $3 2^{3} \times 64$ , lattice spacing $a = 0.0934$ fm, and pion mass $m_{π} = 260$ MeV. Matrix elements are computed for hadron momenta $P_{3} = 0$ , 0.41, 0.83, 1.25, 1.66, and 2.07 GeV and analyzed within the short-distance factorization framework. We investigate the dependence of the extracted moments on the truncation of the operator-product expansion, the coordinate-space fit window, and the perturbative accuracy of the Wilson coefficients, comparing next-to-leading-order and next-to-next-to-leading-order results. We also perform an RG-improved analysis as a consistency check of the perturbative treatment. Our final results are obtained from combined fits in $(P_{3}, z)$ space at next-to-next-to-leading-order and are quoted at $μ = 2$ GeV. We also study the SU(3) symmetry-breaking effect and reconstruct the valence PDFs from the moments.
↳ hep-lathep-exhep-phhep-th2 citations
35
Finite Coherence in Gravitational Waves from Tidally Excited Axion Clouds
Yizhi Liang🇨🇳 · Mian Zhu🇨🇳 · Wen-Biao Han🇨🇳 · Lianfu Wei🇨🇳 · Peng Wang🇨🇳 · Jun Tao🇨🇳
Axion clouds around rotating black holes form gravitational atoms whose tidal transitions can radiate gravitational waves in binaries. For strongly coupled Bohr crossings, transition radiation is governed by the outgoing two-level coherence, not by the transition probability alone. This coherence is suppressed both on the adiabatic branch and in the weak passage limit, but survives for intermediate sweep rates, producing a finite transition waveform and a localized orbital response. In more massive systems, fine and hyperfine transitions produce narrowband gravitational radiation and cumulative departures from vacuum binary waveforms. Coherent tidal crossings offer a gravitational-wave probe of axion-cloud dynamics.
↳ gr-qchep-ph0 citations
36
Spectral densities from Euclidean correlators via integral transforms: theoretical framework
Leonardo Giusti🇮🇹 · Matteo Saccardi🇺🇸 · Diego Toniolo🇮🇹
Spectral densities link experimental measurements to dynamical properties of a quantum field theory which, in turn, can be resolved non-perturbatively from the Euclidean time-dependence of correlation functions. By making extensive use of integral transforms, we present analytic formulae to carry out the inverse Laplace transform so as to extract spectral densities from either the continuum or the discrete sampling of correlation functions in the Euclidean time. Formulae extend to regulated and/or smeared spectral densities as well. We explicitly show that the proposed lattice solution tends to its continuum counterpart up to $O (a^{2})$ effects in the lattice spacing $a$ if the lattice correlator is $O (a)$ -improved. In practical computations, lattices have necessarily a finite Euclidean temporal extent, a lack of knowledge which suggests to introduce incomplete integral transforms and the corresponding incomplete smeared spectral densities. The contribution from the unknowns to a smeared spectral density can then be rigorously bound and kept under control if the integral transform of the smearing function decays fast enough with the conjugate variable. Conversely, the bound can be used to plan lattices so as to achieve a given target precision on the reconstructed spectral density of interest. The formulae presented here in the context of lattice field theory can be easily applied or extended to other areas of research.
↳ hep-lathep-phhep-th4 citations
37
HIcosmo: a differentiable JAX-based framework for cosmology inference
Jing-Zhao Qi🇺🇸 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇺🇸
The Stage IV cosmological surveys, such as Euclid, LSST, DESI, and SKA, will deliver observational data of unprecedented volume, calling for efficient and reliable inference tools. This paper presents HIcosmo (High-performance Inference for Cosmology), an open-source JAX-based framework for cosmology inference. In HIcosmo, the forward model, distance integrals, likelihood evaluations, posterior sampling, and Fisher forecasts are all built from JAX primitives, so that gradients and Hessians of the log-likelihood are obtained directly by automatic differentiation, without any finite-difference approximation. The framework implements the $Λ$ CDM, $w$ CDM, $w_{0} w_{a}$ CDM, and interacting dark-energy models, and provides likelihoods for Type Ia supernovae (Pantheon+, DES-SN5YR, Union3), baryon acoustic oscillations (DESI DR1/DR2, SDSS), Planck 2018 distance priors, local $H_{0}$ measurements, and strong-lensing time delays. Its scope is restricted to background cosmology, with Boltzmann solvers and full perturbation-level likelihoods left to external tools. We validate HIcosmo against the reference implementation of each likelihood and against Cobaya. $χ^{2}$ values agree to absolute differences of $1 0^{- 6}$ - $1 0^{- 2}$ , and the marginalized constraints from the two codes differ by less than $0.2 σ$ in every analysis tested. Leveraging just-in-time compilation and automatic differentiation, HIcosmo achieves about $8.7 \times$ the end-to-end sampling throughput of Cobaya on CPU. As the dataset grows to survey scale, GPU acceleration over CPU reaches up to $20 \times$ . As applications, we present multi-probe $Λ$ CDM joint constraints, dark-energy equation-of-state constraints, and Fisher forecasts for six 21 cm intensity-mapping surveys, including SKA1, MeerKAT, BINGO, Tianlai, and CHIME.
↳ astro-ph.COgr-qchep-ph0 citations
38
Universal EOS-Radius Inverse Mappings Govern Precision-Dependent Inference of the Neutron Star Equation of State
Bao-An Li🇺🇸
Bayesian inference of the neutron star (NS) equation of state (EOS) generally assumes that improved observations primarily reduce posterior uncertainties while leaving inferred EOS parameters unchanged. Using mock measurements of the radius of a canonical $1.4 M_{⊙}$ NS with identical central values but varying observational precisions, we show that the inferred posterior means of EOS parameters can shift systematically as the measurement uncertainty changes. We demonstrate that this behavior originates from previously unidentified nearly universal inverse mappings between the NS radius $R_{1.4}$ and empirical EOS parameters. Across a broad range of observational precisions, posterior samples collapse onto nearly unique functions. These mappings are largely independent of observational precision and define a low-dimensional EOS manifold underlying Bayesian inference. We show that the precision dependence of inferred EOS parameters arises from nonlinear filtering of the posterior radius distribution through these mappings. In the narrow-distribution limit this effect reduces to a Jensen-type correction proportional to the local curvature of the inverse mapping, while for presently realistic uncertainties the full nonlinear-filtering relation accurately reproduces the posterior means. Our results reveal a geometric origin of precision-dependent inference in NS EOS studies and provide a new framework for connecting astrophysical observations directly to microscopic nuclear many-body theories.
↳ nucl-thastro-ph.HEhep-phhep-th+12 citations
39
Efficient calculation of two-neutrino double-beta-decay nuclear matrix elements
Mihai Horoi🇺🇸
Reliable nuclear matrix elements (NMEs) are essential for interpreting double-beta-decay experiments and for connecting measured or constrained half-lives to the underlying weak-interaction physics. The two-neutrino mode ( $2 ν β β$ ) is allowed by the Standard Model and has been observed in several nuclei, whereas the neutrinoless mode ( $0 ν β β$ ) remains the key experimental signature of lepton-number violation and Majorana neutrino masses. Recent statistical shell-model studies indicate a strong correlation between the $2 ν β β$ and $0 ν β β$ NMEs, making accurate and efficient calculations of the former especially useful for assessing the latter. Direct evaluations of $2 ν β β$ NMEs usually require summing over many $1^{+}$ states in the intermediate odd-odd nucleus, a procedure that becomes expensive and may converge slowly in large model spaces. We present and test an improved strength-function method based on Lanczos iterations that avoids full diagonalization while preserving the accuracy of explicit summation where such benchmarks are possible. The method is applied to several experimentally important emitters and to different effective Hamiltonians. We also show that the same framework can be used for the higher-order NMEs entering Taylor-expanded phase-space treatments of $2 ν β β$ and related decay modes.
↳ nucl-thhep-ph0 citations
40
Cancellation of one-loop time dependence in superhorizon curvature perturbations from all scales
Keisuke Inomata🇺🇸
We show the conservation of the superhorizon curvature perturbations at one-loop level in spatially-flat gauge, including contributions from loop wavenumbers on all scales. In contrast to previous works, we do not assume a hierarchy $k ≫ q$ between the wavenumber of the loop integral, $k$ , and that of the power spectrum, $q$ , and we explicitly include the regime $k ≲ q$ . Taking into account the nonlinear relation between the inflaton fluctuation and the curvature perturbation with the $δ N$ formalism, we show that the apparent time dependence of the one-loop curvature power spectrum cancels once all contributions, including boundary terms, are combined consistently.
↳ astro-ph.COgr-qchep-phhep-th2 citations
41
QCD critical surface from constant entropy contours
Hitansh Shah🇺🇸 · Tristan Gyure🇺🇸 · Anabella Leon🇺🇸 · Francesco Di Clemente🇺🇸 · Mauricio Hippert🇧🇷 · Claudia Ratti🇺🇸 · Volodymyr Vovchenko🇺🇸
We provide the first mapping of the critical surface in (2+1)-flavor QCD in the full $(T, μ_{B}, μ_{Q}, μ_{S})$ space, anchored on lattice QCD results at vanishing chemical potentials and obtained within an expansion along contours of constant entropy density. In the pure $μ_{B}$ direction, this framework yields a critical point at $(T_{c}, μ_{B, c}) ≃ (114, 602)$ MeV. Here we extend the construction to arbitrary directions in the three-dimensional chemical-potential space, parametrized by spherical coordinates $(μ, θ, φ)$ , with the radial expansion truncated at $O (μ^{2})$ . The resulting two-dimensional surface carries a direction-dependent critical temperature $T_{c} (θ, φ)$ and baryochemical potential $μ_{B, c} (θ, φ)$ , which quantify the shift of the critical point relative to the pure $μ_{B}$ direction. We find that $μ_{B, c}$ increases by 40-100 MeV along the approximately strangeness neutral direction [ $μ_{S} \approx (0.15$ -- $0.33) μ_{B}$ , $μ_{Q} \approx 0$ ] relevant for heavy-ion collisions, while the critical temperature stays essentially unchanged. In the charge-neutral, weak-equilibrium direction~[ $μ_{Q} \approx - (0.05$ -- $0.1) μ_{B}$ , $μ_{S} = 0$ ] relevant for neutron star mergers, the critical point, and the associated first-order phase transition, remain present at essentially the same location in the $(T, μ_{B})$ plane. We find no evidence for a critical point at large isospin densities, $∣ μ_{Q} ∣/ μ_{B} ≳ 1$ , relevant for cosmic trajectories in the early Universe, nor along the pure electric-charge or strangeness directions, at least outside the regions where pion or kaon condensation may occur.
↳ nucl-thhep-ph0 citations

Affiliations

first authorsco-authorsvia INSPIRE