HEP Phenomenology·hep-ph

Tue·Apr 29, 2025Tuesday·April 29, 2025

44 papers—30 primary·14 cross-listed·reconstructed*

01*
Targets for Flavor-Violating Top Decay
Wolfgang Altmannshofer🇺🇸 · Zev Balme🇺🇸 · Christopher M. Donohue🇺🇸 · Stefania Gori🇺🇸 · Siddharth Vignesh Mukundhan🇺🇸
Analyticity and unitarity constrain certain classe of new physics models by linking flavor-conserving and flavor-violating four-fermion interactions. In this work, we explore how these theoretical relations impact flavor-violating rare top quark decays. Building on our previous results, we present an updated analysis of the decays $t \to q ℓ^{+} ℓ^{-}$ and identify interesting target branching ratios in the range of $1 0^{- 7}$ to $1 0^{- 6}$ once current experimental constraints from flavor-conserving processes are taken into account. We extend the analysis to top decays with lepton flavor violation, deriving correlations among the relevant Wilson coefficients and confronting them with existing limits from LEP and the LHC. Notably, we find that current searches for $t \to q e μ$ are already probing theoretically motivated regions of parameter space. These results strongly support continued efforts to explore flavor-violating top decays as a powerful probe of new physics.
hep-phJHEP(2025)·5 citations
02*
A combined analysis of $Y (2240)$ in the $e^{+} e^{-} \to K^{+} K^{-}$ and $e^{+} e^{-} \to K_{S}^{0} K_{L}^{0}$ processes
Dian-Yong Chen🇨🇳 · Jing Liu🇨🇳 · Yu Bai🇨🇳 · Chun-Hua Liu🇨🇳 · Wen-Biao Yan🇨🇳 · Zhao-Xia Meng🇨🇳
In the present work, we perform a combined analysis of the cross sections for $e^{+} e^{-} \to K^{+} K^{-}$ and $e^{+} e^{-} \to K_{S}^{0} K_{L}^{0}$ by including the interference between direct coupling process and resonance intermediate process. When setting the isospin factor as a free parameter, we can well reproduce the structures in the cross sections for $e^{+} e^{-} \to K^{+} K^{-}$ and $e^{+} e^{-} \to K_{S}^{0} K_{L}^{0}$ , however, the isospin factor deviates with the isospin symmetry conservation predicted value of one. By fixing the isospin factor to be one, we find the cross sections for $e^{+} e^{-} \to K^{+} K^{-}$ can be accurately fitted, while the same model parameters fail to adequately reproduce the observed cross section for the process $e^{+} e^{-} \to K_{S}^{0} K_{L}^{0}$ , which indicate that there should be contributions from other vector meson states, such as $ρ (2150)$ and $ω (2220)$ . More precise experimental measurement below 2.0 GeV and between $2.3 \sim 2.5$ GeV may provide more information about the vector resonances in this energy range, which should be accessible for the BESIII collaboration.
hep-phEPJC(2025)·1 citation
03*
Geometric scaling of elastic $pp$ cross section at the LHC
Michał Praszałowicz🇵🇱
We show that geometric scaling conjectured and observed at the ISR more than 50 years ago, still holds at the LHC. We discuss regularities of the dip-bump structures of the differential elastic cross sections, emphasizing the fact that the ratio of bump to dip positions is constant from the ISR to the LHC. Applying crossing and analyticity we identify imaginary and real parts of the scattering amplitude and compute the $ρ$ parameter and the ratio of bump to dip values of the differential $pp$ cross sections. We also discuss the energy dependence of the total elastic cross section and the violation of geometrical scaling outside the dip-bump region at the LHC.
hep-phPLB(2025)·4 citations
04*
Moat regimes within a $2 + 1$ flavor Polyakov-quark-meson model
Gaoqing Cao🇨🇳
To better understand recent predictions on the moat regime of quantum chromodynamics (QCD) matter, this paper extends the previous work within the two-flavor quark-meson (QM) model to the more realistic $2 + 1$ flavor Polyakov-quark-meson (PQM) model. Mainly, two effects are further taken into account: strange quark and confinement coded through Polyakov loop. Model parameters are chosen to consistently reproduce the pseudocritical temperature from lattice QCD, $T_{C} \sim 156 MeV$ , and the baryon chemical potential at the critical end point (CEP) from FRG-QCD, $μ_{B (CEP)} \sim 635 MeV$ . It is found that the basic features of moat regimes for $σ$ and $π$ mesons remain similar to those from QM model: Moat regimes cover the region where temperature or baryon chemical potential is large; reentrances occur around the critical baryon chemical potential of chiral transition at zero temperature. Thus, the FRG-QCD results can still not be well understood, especially why the CEP should locate at the entrances of moat regimes for $σ$ and $π$ mesons. Nevertheless, some basic features can be understood qualitatively, and it is consistent that the pole energies are increasing functions of momenta in the whole $T - μ_{B}$ plane. The moat regime and pole energy of $K$ mesons are also studied with the features similar.
hep-phnucl-thPRD(2025)·7 citations
05*
Lorentz and CPT violation and the hydrogen and antihydrogen molecular ions II -- hyperfine-Zeeman spectrum
Graham M Shore🇬🇧
Fundamental principles of quantum field theory such as Lorentz invariance, CPT symmetry and locality may be tested to extremely high precision in atomic and molecular spectroscopy. The narrow natural linewidth of rovibrational states in the hydrogen molecular ion $H_{2}^{+}$ and its antimatter counterpart $H ˉ_{2}^{-}$ , make these ideal candidates, and give $O (m_{p} / m_{e})$ increased sensitivity to Lorentz and CPT violation in the proton sector compared to $H$ and $H ˉ$ atoms. In a previous paper, we presented a detailed analysis of the rovibrational spectrum of $H_{2}^{+}$ and $H ˉ_{2}^{-}$ in an effective QFT encoding Lorentz and CPT violation, focusing on spin-independent effects. Here, we extend this analysis to include the full hyperfine-Zeeman spectrum and include spin-dependent Lorentz and CPT violating operators in the effective theory. The results demonstrate how constraints on these symmetry-violating couplings may be extracted from specific rovibrational transitions between hyperfine-Zeeman states in the presence of an applied magnetic field.
hep-phphysics.atom-phPRD(2025)·3 citations
06*
Searching for elusive dark Higgs boson in spin-1/2 inelastic dark matter models at Belle II
P. Ko🇰🇷 · Youngjoon Kwon🇰🇷 · Chih-Ting Lu🇨🇳 · Xinqi Wei🇨🇳
Spin-1/2 inelastic dark matter (DM) models are popular among sub-GeV to GeV thermal DM scenarios due to the dominant role of co-annihilation in determining the DM relic abundance. In these models, the dark Higgs boson plays a crucial role in generating the mass of the new gauge boson, the dark photon ( $A^{'}$ ), and in establishing the mass splitting between the excited ( $χ_{2}$ ) and ground ( $χ_{1}$ ) states of DM. In particular, the Compton scattering $χ_{1} A^{'} \to χ_{2}^{*} \to χ_{1} A^{'}$ and its $t$ -channel crossed process, $χ_{1} χ_{1} \to A^{'} A^{'}$ , remain unitary for high energy longitudunal dark photon, only if the contribution of the dark Higgs boson is included. However, experimental searches for the dark Higgs boson have received relatively little attention. In particular, when the dark Higgs boson mass exceeds twice that of the DM excited state, its decay signatures become semi-visible or invisible, making detection challenging with current light scalar search strategies. In this work, we explore the prospects for detecting the elusive dark Higgs boson in spin-1/2 inelastic DM models at Belle II via dark Higgs-strahlung and rare $B$ meson decay processes. Our analysis indicates that both the inclusive signature of two displaced dilepton vertices and the additional missing energy from dark Higgs boson decays serve as robust indicators of its presence. Furthermore, we assess the future potential for detecting the dark Higgs boson with the proposed far detector related to Belle II, GAZELLE.
hep-phJHEP(2025)·6 citations
07*
A scale invariant extension of the Georgi Machacek model
Hamza Taibi🇩🇿
We propose a classically scale-invariant extension of the Georgi--Machacek model by augmenting its custodial $SU(2)_L \times SU(2)_R$-symmetric Higgs sector -- originally composed of a doublet and two triplets -- with a gauge-singlet scalar. Employing the Gildener--Weinberg formalism, we demonstrate that radiative symmetry breaking via the Coleman--Weinberg mechanism dynamically generates the electroweak scale along a flat direction. The scalar spectrum retains the quintet ($H_5$) and triplet ($H_3$) states of the original model while introducing three CP-even singlets: a pseudo-Goldstone boson (the \emph{scalon}), which acquires mass at one loop, and two additional massive scalars. One of these massive states corresponds to the observed $125\,\mathrm{GeV}$ Higgs boson. We rigorously derive theoretical constraints from vacuum stability and perturbative unitarity, and we incorporate experimental bounds from electroweak precision tests (notably the $S$ parameter) and Higgs signal strength measurements. Our parameter space analysis identifies viable regions where the scalon mass is below approximately $200\,\mathrm{GeV}$ and the heavier scalar remains under $600\,\mathrm{GeV}$. This framework addresses the hierarchy problem without fine-tuning, preserves custodial symmetry (with $\rho \approx 1$ at tree level), and predicts testable deviations in Higgs couplings. Together with the extended scalar sector, these signatures provide promising avenues for direct investigation at collider experiments.
hep-phNPB(2026)·0 citations
08*
Full analysis of CP violation induced by the decay angular correlations in four-body cascade decays of heavy hadrons
Zhen-Hua Zhang🇨🇳 · Jian-Yu Yang🇨🇳 · Xin-Heng Guo🇨🇳
The violation of the charge-parity (CP) transformation symmetry, which although has been observed in plenty of pure meson decay processes, was only confirmed just very recently by the LHCb collaboration in the four-body decay of the heavy baryon $Λ_{b}^{0}$ , $Λ_{b}^{0} \to p K^{-} π^{+} π^{-}$ , through a comparison of the decay branching ratio with that of the CP-conjugate process. However, the detailed dynamics behind this CP asymmetry is obviously far from clear. In this paper, we propose a formalism for the full analysis of the decay angular correlations in four-body cascade decays of heavy hadrons which can provide more information about the CP violation in these decays. To illustrate this, we apply the decay angular correlation analysis of CP violation to another four-body decay channel that involve baryons, $B^{0} \to p p ˉ K^{+} π^{-}$ , which has also been investigated by the LHCb collaboration with no evidence of CP violation being found. Surprisingly, based on a simple assumption on the statistical errors, and with the event yield extracted inversely from the published data of LHCb, we obtain non-zero CP asymmetries of about $10%$ corresponding to the decay angular correlations, which are considerably larger than the CPA asymmetries observed in the $Λ_{b}^{0} \to p K^{-} π^{+} π^{-}$ channel. We suggest our experimental colleagues to perform full decay angular correlation analyses of CP violation in four-body decays of heavy hadrons, including the above two decay channels.
hep-phhep-exChin.Phys.Lett.(2026)·4 citations
09*
The influence of majorons on neutrino oscillations in the presence of a magnetic field and matter
A.Lichkunov🇷🇺 · A.Popov🇷🇺 · A.Studenikin🇷🇺
Neutrino spin-flavour oscillations in the magnetic field, matter, and majoron fields are studied. The effective Lagrangian of Majorana neutrino interaction with a majoron field mediated by heavy neutrino is calculated. It is shown that the presence of a majoron field with a high energy density significantly shifts the resonances in neutrino oscillations, or even induces new resonances. The influence of the majoron suppresses oscillations for neutrino energies below 10 MeV. Additionally, the dependence of the oscillations probabilities on the Dirac and Majorana CP-violating phases becomes weaker under the influence of a dense majoron field. These findings can be applied to experiments that study neutrinos from supernovae, such as JUNO, DUNE, and the upcoming Hyper-Kamiokande experiment.
hep-phhep-thPhys.Atom.Nucl.(2026)·2 citations
10*
Non-Markovian dynamics of bottomonia in the QGP
Vyshakh B R🇮🇳 · Rishi Sharma🇮🇳
The evolution of quarkonia in the QGP medium can be described through the formalism of Open Quantum Systems (OQS). In previous works with OQS, the quarkonium evolution was studied by working in either quantum Brownian or optical regime. In this paper, we set up a general non-Markovian master equation to describe the evolution of the quarkonia in the medium. Due to the non-Markovian nature, it cannot be cast in Lindblad form which makes it challenging to solve. We numerically solve the master equation for $Υ (1 S)$ without considering stochastic jumps for Bjorken and viscous hydrodynamic background at energies relevant to LHC and RHIC. We quantify the effect of the hierarchy between the system time scale, $τ_{S} \sim 1/ E_{b}$ , and the environment time scale, $τ_{E}$ , on quarkonium evolution and show that it significantly affects the nuclear modification factor. A comparison of our results with the existing experimental data from LHC and RHIC is presented.
hep-phPRD(2025)·5 citations
11*
Exploring bottom-charmed molecular tetraquarks with the complex scaling method
Qing-Fu Song🇨🇳 · Wei Liang🇨🇳 · Qi-Fang Lü🇨🇳 · Xiao-Nu Xiong🇨🇳
In this work, we adopt the one-boson exchange model to analyze the $D_{(s)}^{(*)} B_{(s)}^{(*)}$ interactions from a coupled-channel perspective. For the $I (J^{P}) = 1 (1^{+})$ $D B^{*} / D^{*} B / D^{*} B^{*}$ system, employing the complex scaling method, we obtain a loosely bound state and two resonant states located below the $D B^{*}$ , $D^{*} B$ , and $D^{*} B^{*}$ thresholds, respectively. Assuming that the charmonium-like states $T_{c c ˉ 1} (3900)$ and $T_{c c ˉ 1} (4020)$ , as well as the bottomonium-like states $T_{b b ˉ 1} (10610)$ and $T_{b b ˉ 1} (10650)$ , are molecular states near their respective thresholds, we suggest that the predicted states in the $I (J^{P}) = 1 (1^{+})$ $D_{(s)}^{(*)} B_{(s)}^{(*)}$ system could be their bottom-charmed analogues. In addition, we extend our analysis to other $D_{(s)}^{(*)} B_{(s)}^{(*)}$ combinations with various quantum numbers. Our results suggest that some exotic structures may exist in the bottom-charmed sector. Finally, we collect the possible decay channels for future experimental observations. The $B_{c} / B_{c}^{*}$ plus a light meson are the ideal final state to search for the bound states, while the $D_{(s)}^{(*)} B_{(s)}^{(*)}$ channels are suitable for the resonances. We highly recommend that the future experiments hunt for these bottom-charmed exotic particles.
hep-phPRD(2026)·1 citation
12*
Different scenarios of dynamical chiral symmetry breaking in the interacting instanton liquid model via flavor symmetry breaking
Yamato Suda🇯🇵 · Daisuke Jido🇯🇵
We investigate a type of dynamical chiral symmetry breaking (D $χ$ SB) for various current quark masses using the interacting instanton liquid model. The type of D $χ$ SB is classified based on the sign of the second derivative of the free energy density with respect to the quark condensate at the origin. We perform numerical simulations of the interacting instanton liquid model with the flavor SU(2) symmetric and (2+1)-flavor quarks. We find that the curvature is negative in the SU(2) case. This means the ordinary type of D $χ$ SB. In contrast, in the (2+1)-flavor case, a positive curvature is observed when the strange quark mass is as small as those of the up and down quarks. This suggests that the anomaly-driven type of D $χ$ SB can occur under the approximate flavor SU(3) symmetry. As the strange quark mass increases, the curvature gradually decreases and becomes negative when the strange quark mass is approximately three times larger than those of the light quarks. This difference can be understood in terms of the 't Hooft vertex which induces a six-quark interaction in the $N_{f} = 3$ case and does a four-quark interaction in the $N_{f} = 2$ case. Our results might indicate that the ratio between the strange and light quark masses plays a crucial role in understanding the microscopic relationship between D $χ$ SB and the anomaly effect.
hep-phnucl-thPRD(2025)·1 citation
13*
Properties of $X (3872)$ from hadronic potentials coupled to quarks
Ibuki Terashima🇯🇵 · Tetsuo Hyodo🇯🇵
The concept of compositeness is used to quantitatively discuss the hadronic molecular nature in exotic hadrons. In this work, we develop a formulation to explicitly introduce the compact quark state contribution in the hadronic potentials together with the direct four-point interaction. We derive analytic expressions of the compositeness from the effective potential between hadrons when the system has a bound state. Applying this formulation to the $X (3872)$ , we examine the variation of the compositeness with respect to the binding energy, energy of $χ_{c 1} (2 P)$ , cutoff momentum, and strength of the direct $D^{0} D ˉ^{* 0}$ interaction.
hep-phnucl-thPoS(2025)·0 citations
14*
Exploring Ultralight Dark Matter Self-Coupling via the Gravitational Wave Background
Pratick Sarkar🇮🇳
Supermassive black hole (SMBH) binary mergers are a primary source of the stochastic gravitational wave background (SGWB) in the nanohertz band, now being actively probed by pulsar timing arrays (PTAs). We investigate how ultralight dark matter (ULDM) with a quartic self-interaction, forming solitonic cores around SMBHs, modifies the SGWB through dynamical friction on the inspiralling binary. Solving the Gross--Pitaevskii--Poisson (GPP) equations numerically for halo masses $M_{halo} \sim 1 0^{13} M_{⊙}$ , we compute self-consistent solitonic density profiles across a range of dimensionless self-coupling parameters $λ^$ , covering both attractive and repulsive self-interactions. We find that soliton-induced dynamical friction imprints a characteristic suppression feature in the GW strain spectrum, whose frequency location and depth are sensitive to both the ULDM mass $m$ and the coupling $λ^$ . For SMBH masses $M_{∙} \sim 1 0^{8.5} M_{⊙}$ and ULDM masses in the range $m \sim (3 \times 1 0^{- 22} - 2 \times 1 0^{- 21}) eV$ , current PTA observations from NANOGrav, EPTA, and PPTA may place qualitative limits on the attractive and repulsive self-coupling of ULDM particles. ULDM masses exceeding $\sim 1.6 \times 1 0^{- 21} eV$ are independently excluded by soliton accretion-timescale constraints. These results demonstrate that the nanohertz GW spectrum provides a complementary probe of ULDM self-interactions, operating in a regime distinct from conventional particle-scattering or rotation-curve analyses.
hep-phastro-ph.GAgr-qcJ.Phys.G(2026)·7 citations
15*
The impact of the TMD shape function on matching the transverse momentum spectrum in $J / ψ$ production at the EIC
Luca Maxia🇳🇱 · Daniël Boer🇳🇱 · Jelle Bor🇳🇱
The impact of the inclusion of TMD shape functions on the transverse momentum spectrum in $J / ψ$ production at the EIC is investigated by considering the matching of the TMD factorization description at low transverse momentum with the collinear factorization description at high transverse momentum by means of the inverse-error weighting method. Despite large uncertainties from scale variations and the $J / ψ$ long-distance matrix elements, predictions for the differential cross section and its $cos (2 ϕ_{ψ})$ modulation are obtained. We find that physical constraints are satisfied in case a process-dependent term is included for color octet production, but not in all cases when it is excluded. These numerical results support the analytic calculations in \cite{Boer:2023zit}. Future experimental data can thus test the validity of TMD factorization in $J / ψ$ production and explore the presence of nontrivial process-dependent effects in the soft-gluon resummation. This will be crucial in the extraction of gluon unpolarized and linearly polarized TMD distributions of the proton. In addition, we suggest how the sign of the latter can be determined by investigating the presence of a node in the $cos (2 ϕ_{ψ})$ modulation as a function of transverse momentum.
hep-phPRD(2025)·5 citations
16*
The asymmetry $A_{LL}^{c o s 2 ϕ}$ in the polarized proton-proton Drell-Yan process within TMD factorization
Hui Li🇨🇳 · Ting Hu🇨🇳 · Liang-Liang Liu🇨🇳 · Xiao-Yu Wang🇨🇳 · Zhun Lu🇨🇳
We study the $cos 2 ϕ$ azimuthal asymmetry in doubly longitudinally polarized proton-proton Drell-Yan collisions within the transverse momentum dependent factorization framework. The asymmetry arises from the convolution of the longitudinal transversity distribution $h_{1 L}^{⊥}$ for both protons. Using the Bacchetta-Delcarro-Pisano-Radici-Signori parametrization for the nonperturbative Sudakov form factor and the Wandzura-Wilczek approximation for the collinear $h_{1 L}^{⊥}$ , we predict the double spin asymmetry $A_{LL}^{c o s 2 ϕ}$ at RHIC and NICA kinematics. Our results demonstrate sensitivity to sea quark distributions, with the asymmetry reaching up to $25%$ for maximal sea quark contributions. These predictions highlight the potential of polarized Drell-Yan measurements to probe sea quark dynamics and advance our understanding of nucleon structure.
hep-phCPC(2025)·1 citation
17*
Emerging Photon Jets in the Hadronic Calorimeter: A Novel Signature of Neutral Long-Lived Particles at the LHC
Jinheung Kim🇰🇷 · Dongjoo Kim🇰🇷 · Soojin Lee🇰🇷 · Jeonghyeon Song🇰🇷
We propose a novel collider signature for neutral long-lived particles (LLPs): the emerging photon jet in the hadronic calorimeter (HCAL). This signature arises when a neutral LLP decays into photons within the HCAL, producing an electromagnetic shower without associated charged tracks or energy deposits in the electromagnetic calorimeter (ECAL). To demonstrate the viability of this approach, we consider the fermiophobic Higgs boson $h_{f}$ in the Type-I two-Higgs-doublet model as a representative scenario. In the ultralight regime ( $m_{h_{f}} < 1$ GeV), $h_{f}$ decays exclusively into a photon pair via loop-induced processes, resulting in a suppressed width and consequently a long lifetime. Focusing on the golden channel $pp \to H^{\pm} h_{f} \to W^{\pm} h_{f} h_{f}$ , we analyze the exotic final state in which one $h_{f}$ decays in the ECAL and appears as a highly collimated photon jet (reconstructed as a single photon), while the other decays within the HCAL, producing an emerging photon jet. Through a detailed signal-to-background analysis incorporating realistic detector effects via fast simulation, we demonstrate that this signature achieves discovery-level sensitivity at the HL-LHC across a broad region of parameter space consistent with theoretical and experimental constraints. While our study focuses on the fermiophobic Higgs, the emerging photon jet in the HCAL constitutes a broadly applicable and previously unexplored strategy for detecting neutral LLPs decaying into photons, opening a new avenue in LLP searches at colliders.
hep-phPLB(2025)·5 citations
18*
Rescuing leptogenesis in inverse seesaw models with the help of non-Abelian flavor symmetries
Yan Shao🇨🇳 · Zhen-hua Zhao🇨🇳
The inverse seesaw (ISS) model provides an attractive framework that can naturally explain the smallness of neutrino masses while accommodating some sterile neutrinos potentially accessible at present or future experiments. However, in generic ISS models with hierarchical pseudo-Dirac (PD) sterile neutrino pairs, the generation of the observed baryon asymmetry of the Universe via the leptogenesis mechanism is extremely challenging. In this paper, we investigate rescuing leptogenesis in the ISS model with the help of non-Abelian flavor symmetries which have the potential to explain the observed peculiar neutrino mixing pattern: we first implement non-Abelian flavor symmetries to naturally enforce mass degeneracies among different pseudo-Dirac sterile neutrino pairs and then break them in a proper way so that resonant leptogenesis among different PD sterile neutrino pairs can arise, thus enhancing the generated baryon asymmetry. To be specific, we have considered the following two well-motivated approaches for generating the tiny mass splittings among different PD sterile neutrino pairs: one approach makes use of the renormalization-group corrections to the sterile neutrino masses, while the other approach invokes non-trivial flavor structure of the $μ_{s}$ matrix. For these two scenarios, we aim to explore the viability of leptogenesis and to identify the conditions under which the observed baryon asymmetry can be successfully reproduced.
hep-phPRD(2026)·2 citations
19*
Fast numerical evaluation of dark matter direct detection event rates
Sebastian Sassi🇫🇮 · Aula Al-Adulrazzaq🇫🇮 · Matti Heikinheimo🇫🇮 · Kimmo Tuominen🇫🇮
The mathematical expression for the dark matter nuclear recoil event rate in a detector consists of a six dimensional integral over the velocity distribution of dark matter in the detector frame, and over the recoil momentum of the nucleus. While a significant part of this integral can be solved in closed form under traditional assumptions of the standard halo model and/or isotropic detector response, analysis of alternate assumptions is conventionally impeded by the inefficiency of multidimensional numerical integration methods. In this work we introduce a novel, fast and efficient algorithm for direct detection event rate computations. This algorithm takes advantage of a closed form expression for the Radon transform of three dimensional Zernike functions, which are used as basis functions for the velocity distribution. We demonstrate an implementation of this algorithm ZebraDM (https://github.com/sebsassi/zebradm), which is typically faster than an optimized numerical integration approach by a factor between $1 0^{2}$ and $1 0^{4}$ .
hep-phPRD(2025)·2 citations
20*
Collision parameters needed to measure polarisation-dependent nonlinear pair creation
Mathias Samuelsson🇸🇪 · Thomas G. Blackburn🇸🇪
Pair creation by a $γ$ ray in a high-intensity electromagnetic field (the nonlinear Breit-Wheeler process) is sensitive to the $γ$ -ray polarisation. Here we study the stability required in order to measure this polarisation dependence in a head-on collision between a high-power linearly polarised laser and a relativistic electron beam, where the $γ$ -rays produced via nonlinear Compton scattering are highly polarised. We find that the laser strength parameter $a_{0}$ has to be known to within a few per cent, and that the alignment of the laser and electron beam cannot fluctuate by more than half the spot size, in order to attribute the reduction in positron yield to polarisation effects. These collision parameters are difficult to achieve, but may be realised in future precision experiments that focus on beam stability.
hep-phphysics.plasm-phPRA(2025)·0 citations
21*
Meson scattering and tetraquarks in two-dimensional QCD
Hagop Sazdjian🇫🇷
Two-quark--two-antiquark systems with four different quark flavors are considered in the framework of two-dimensional QCD, in the light-cone gauge, at leading orders of the $1/ N_{c}$ expansion. Introducing basis functions with color-singlet mesonic clusters, integral equations are established for the Green's functions and the related scattering amplitudes involved in the sectors of the direct and quark-exchange channels. The problem of infrared divergences is dealt with via a systematic use of an infrared regulator cutoff introduced in the gluon propagator. It is shown that the on-mass shell scattering amplitudes are free of infrared divergences up to order $1/ N_{c}^{2}$ . In the limit of vanishing of the infrared cutoff, they can be represented by effective four-meson contact-type interaction terms with unitarity loops, calculable in terms of the meson wave functions and propagators. The results, obtained at order $1/ N_{c}^{2}$ , are summed with the constraint of unitarization. The unitarized scattering amplitudes are continued in the total mass-squared variable below the two-meson thresholds, leading to a tetraquark bound state equation, which generally has one solution. Spectroscopic applications of the above results are sketched and discussed.
hep-phPRD(2025)·0 citations
22*
Cosmic strings in the complex symmetron model
Ali Nezhadsafavi🇨🇦 · Levon Pogosian🇨🇦
We study cosmic strings in the complex symmetron model, a scalar-tensor theory with a spontaneously broken local $U (1)$ symmetry in low matter density regions. Using numerical simulations, we show that these strings preferentially attach to matter halos, leading to the stabilization of string loops. While the requirement for screening of fifth-force interactions in the solar system limits observable signatures in theories with universal coupling to matter, analogous topological defects in the dark sector may still influence cosmic structure formation, offering a novel avenue to constrain dark-sector interactions.
hep-phastro-ph.COgr-qchep-thPRD(2025)·2 citations
23*
Pseudo-Nambu-Goldstone-boson Dark Matter from Three Complex Scalars
Riasat Sheikh🇯🇵 · Takashi Toma🇯🇵 · Koji Tsumura🇯🇵
This study explores a dark matter model in which a pseudo-Nambu-Goldstone boson arises as a viable dark matter candidate from the spontaneous and soft breaking of global $U (1)$ symmetries and stabilized by a residual $Z_{3}$ discrete symmetry. The model introduces three complex scalar fields, singlets under the Standard Model gauge group, and charged under a dark $U (1)_{V}$ gauge symmetry together with a permutative exchange symmetry among three scalars. These features naturally suppress the dark matter--nucleon scattering cross section by its Nambu-Goldstone boson nature. In addition to conventional annihilation channels, the $Z_{3}$ structure allows semi-annihilation processes, playing a crucial role in setting the relic abundance.We analyze theoretical and experimental constraints, including relic abundance, Higgs invisible decays, and perturbative unitarity, and evaluate the elastic scattering cross section for boosted dark matter.
hep-phJHEP(2025)·3 citations
24*
Analytic reconstruction with massive particles: one-loop amplitudes for $0 \to q ˉ q t t ˉ H$
John M. Campbell🇺🇸 · Giuseppe De Laurentis🇬🇧 · R. Keith Ellis🇬🇧
We present an analytic reconstruction of one-loop amplitudes for the process $0 \to q ˉ q t t ˉ H$ . Our calculation is a novel use of analytic reconstruction, retaining explicit covariance in the massive spin states through the massive spinor-helicity formalism. The analytic reconstruction relies on embedding the massive five-point kinematics in a fully massless eight-point phase space while still building a minimal ansatz directly in the five-point phase space. In order to obtain compact analytic expressions it is necessary to identify suitable partial fraction decompositions and extract common numerator factors, which we achieve through careful inspection of limits in which pairs of denominators vanish. We find that the resulting amplitudes are more numerically efficient than ones computed using automatic methods but that the gains are not as significant as in the massless case, at least at present. The method opens the door to applications at two-loop order, where numerical efficiency and improvements in the reconstruction methodology are more crucial, especially with regards to the number of free parameters in the ansatz.
hep-phJHEP(2025)·5 citations
25*
Narrow Spectra in Heavy Quark Systems
Estia Eichten🇺🇸
Opportunities to observe new hadrons with very narrow widths are discussed. Two areas of focus are the lowest P-states of heavy-light mesons and doubly heavy baryons.
hep-phhep-exPoS(2025)·1 citation
26*
How Charged Can Neutrinos Be?
Sudip Jana🇮🇳 · Michael Klasen🇩🇪 · Vishnu P.K
We investigate how neutrinos may acquire small electric charges within the Standard Model framework while preserving electromagnetic gauge invariance. Instead of gauging the standard hypercharge generator $Y$ , a linear combination of $Y$ and a new generator $X$ from a gaugable global $U (1)_{X}$ symmetry is embedded, under which neutrinos transform non-trivially. We demonstrate that minimal scenarios based on flavor-dependent $U (1)_{X}$ symmetries, such as $X = L_{α} - L_{β}$ , are incompatible with current neutrino oscillation data. In contrast, we have shown that only flavor-universal $U (1)_{X}$ symmetries-such as $U (1)_{B - L}$ , which shifts both quark and lepton charges, and $U (1)_{L}$ , which modifies only the lepton sector-can generate tiny neutrino charges consistent with observed masses and mixing. We also discuss the necessary connection between such charges and the Dirac nature of neutrinos. By analyzing the phenomenological implications in detail, our findings emphasize that constraints on neutrino charges should be evaluated within the specific framework of the $U (1)_{X}$ symmetry under consideration, rather than assuming a generic approach, as is often the case.
hep-phastro-ph.HEhep-exhep-th4 citations
27*
Up-type FCNC in presence of Dark Matter
Subhaditya Bhattacharya🇮🇳 · Lipika Kolay🇮🇳 · Dipankar Pradhan🇮🇳 · Abhik Sarkar🇮🇳
Dark Matter (DM) is a known unknown. Apart, current experimental constraints on flavor-changing neutral current (FCNC) processes involving up-type quarks also provide scope to explore physics beyond the Standard Model (SM). In this article, we establish a connection between the flavor sector and the DM sector with minimal extension of the SM. Here a singlet complex scalar field, stable under $Z_{3}$ symmetry, acts as DM and couples to SM up-type quarks through a heavy Dirac vector-like quark (VLQ), which shares the same $Z_{3}$ charge as of the DM. The model thus addresses the observed $D^{0} - D^{0} ˉ$ mixing, top-FCNC interactions, and $D^{0}$ meson decays, together with DM relic density, while evading the direct and indirect DM search bounds. The model can be probed at the future high-energy muon collider, through distinctive signatures of VLQ production, where the VLQ decays into DM and SM particles, abiding by the existing bounds.
hep-phhep-exJHEP(2026)·6 citations
28*
The Weak Gravity Conjecture in Asymptotically Safe Quantum Gravity
Gayatri Ghosh🇮🇳
The Weak Gravity Conjecture (WGC) posits that gravity must be the weakest force in any consistent theory of quantum gravity. Originally formulated to constrain the landscape of effective field theories arising from string theory, the WGC suggests the existence of states with a charge-to-mass ratio larger than that of extremal black holes. In this work, we revisit the WGC within the framework of Asymptotically Safe Quantum Gravity, a non-perturbative approach where gravitational and gauge couplings flow to a non-Gaussian ultraviolet (UV) fixed point. We construct a scale-dependent effective action, derive quantum-corrected Reissner--Nordström black hole solutions by incorporating position-dependent renormalization scale identification, and compute leading quantum corrections to the extremality condition. Our key finding is that the quantum correction to the extremal charge-to-mass ratio is dominantly governed by the running of the gauge coupling, characterized by a correction parameter $δ \sim ϵ_{e} (ℓ_{P} / r_{+})^{2 θ}$ , where $ϵ_{e}$ captures deviations from infrared behavior. We show that if the electromagnetic coupling grows in the UV ( $ϵ_{e} > ϵ_{G}$ ), the WGC is dynamically strengthened, whereas if it decreases ( $ϵ_{e} < ϵ_{G}$ ), large extremal black holes may violate the WGC unless additional light charged states exist. Our analysis demonstrates that Asymptotic Safety provides a concrete ultraviolet mechanism influencing low-energy swampland criteria, offering a deep UV/IR connection between quantum gravity consistency and effective field theory behavior.
hep-phgr-qc1 citation
29*
Induced Gravitational Waves as Cosmic Tracers of Leptogenesis
Marco Chianese🇮🇹 · Guillem Domènech🇩🇪 · Theodoros Papanikolaou🇮🇹 · Rome Samanta🇮🇹 · Ninetta Saviano🇮🇹
We demonstrate that induced gravitational waves (IGWs) can naturally emerge within well-motivated realizations of thermal leptogenesis, thereby providing a possible observational handle on this framework at remarkably high energy scales. To illustrate this principle, we put forth a simple leptogenesis model in which an early matter-dominated phase, connected to the leptogenesis scale, enhances the generation of gravitational waves induced by early structure formation. Leveraging recent N-body and lattice simulation results for IGW computations in the non-linear regime, we show that, within the assumptions of the model, the frequency and amplitude of these IGWs can be correlated with the thermal leptogenesis scale.
hep-phastro-ph.COgr-qcJCAP(2026)·8 citations
30*
Shear and bulk viscosity for a pure glue theory using an effective matrix model
Manas Debnath🇮🇳 · Ritesh Ghosh🇺🇸 · Najmul Haque🇮🇳 · Yoshimasa Hidaka🇯🇵 · Robert D. Pisarski🇺🇸
At nonzero temperatures, the deconfining phase transition can be analyzed using an effective matrix model to characterize the change in holonomy. The model includes gluons and two-dimensional ghost fields in the adjoint representation, or ``teens''. As ghosts, the teen fields are responsible for the decrease of the pressure as $T \to T_{d}$ , with $T_{d}$ the transition temperature for deconfinement. Using the solution of this matrix model for a large number of colors, the parameters of the teen fields are adjusted so that the expectation value of the Polyakov loop is close to the values from the lattice. The shear, $η$ , and bulk, $ζ$ , viscosities are computed in weak coupling but nonzero holonomy. In the pure glue theory, the value of the Polyakov loop is relatively large in the deconfined phase, $\approx 1/2$ at $T_{d}$ . Consequently, if $s$ is the entropy density, while $η / s$ decreases as $T \to T_{d}$ , it is still well above the conformal bound. In contrast, $ζ / s$ is largest at $T_{d}$ , comparable to $η / s$ , then falls off rapidly with increasing temperature and is negligible by $\sim 2 T_{d}$ .
hep-phhep-latnucl-thPRD(2025)·4 citations
31*
Asymmetric warm nuclear matter described by Gogny and Skyrme-version models
Odilon Lourenço🇧🇷 · Mariana Dutra🇧🇷 · Mario Centelles🇪🇸 · Xavier Viñas🇪🇸
In this work, we perform a detailed study of the thermodynamical properties of asymmetric nuclear matter at finite temperatures by means of the Gogny force, with a particular focus on its D1 family. We emphasize the investigation of the liquid-gas phase transition with the respective analysis of phase-coexistence boundaries (binodal sections) and instability regions (spinodal contours). Furthermore, the phenomenon of isospin distillation, intrinsically related to the unstable part of the system, is also described. In order to estimate the impact of the finite range of the nuclear interaction, for each Gogny parametrization we provide a respective zero-range Skyrme version, for which the free parameters of the model are obtained with the aim of reproducing at zero temperature the same saturation density, binding energy, incompressibility, isoscalar effective mass, isovector effective mass, symmetry energy, and symmetry energy slope. As a main result, we verify systematic deviations between the Gogny models and their Skyrme-version models, particularly at higher temperatures, where the Skyrme-version parametrizations exhibit reduced binodal and spinodal regions.
↳ nucl-thhep-phPRC(2025)·0 citations
32*
Symmetry Energy Expansion with Strange Dense Matter
Yumu Yang🇺🇸 · Nikolas Cruz Camacho🇺🇸 · Mauricio Hippert🇧🇷 · Jacquelyn Noronha-Hostler🇺🇸
The quantum chromodynamics (QCD) phase diagram at large densities and low temperatures can be probed using both neutron stars and low-energy heavy-ion collisions. Heavy-ion collisions are nearly isospin-symmetric systems, whereas neutron stars are highly isospin asymmetric since they are neutron-rich. The symmetry-energy expansion is used to connect these regimes across isospin asymmetry. However, the current symmetry-energy expansion does not account for strange particles. In this work, we include finite strangeness by redefining the isospin-asymmetry parameter and the symmetry-energy expansion in a way that is consistent with QCD SU(3) flavor symmetry. Our new symmetry energy works well beyond typical neutron star central densities and admits a skewness term in the presence of strangeness for the case of weak equilibrium.
↳ nucl-thastro-ph.HEhep-phPRC(2026)·12 citations
33*
Superradiant dark matter production from primordial black holes: Impact of multiple modes and gravitational wave emission
Nayun Jia🇺🇸 · Shou-Shan Bao🇨🇳 · Chen Zhang🇺🇸 · Hong Zhang🇨🇳 · Xin Zhang🇺🇸
Rotating primordial black holes (PBHs) in the early universe can emit particles through superradiance, a process particularly efficient when the particle's Compton wavelength is comparable to the PBH's gravitational radius. Superradiance leads to an exponential growth of particle occupation numbers in gravitationally bound states. We present an analysis of heavy bosonic dark matter (DM) production through three gravitational mechanisms: Hawking radiation, superradiant instabilities, and ultraviolet (UV) freeze-in. We consider PBHs that evaporate before Big Bang Nucleosynthesis (BBN). For both scalar and vector DM, our analysis incorporates the evolution of a second superradiant mode. We demonstrate that the growth of a second superradiant mode causes the decay of the first mode, and thus the second mode cannot further enhance the DM abundance beyond that already achieved by the first mode. Our study also reveals that while superradiance generally enhances DM production, gravitational wave (GW) emission from the superradiant cloud may significantly modify this picture. For scalar DM, GW emission reduces the parameter space where superradiance effectively augments relic abundance. For vector DM, rapid GW emission from the superradiant cloud may yield relic abundances below those achieved through Hawking radiation alone. These findings demonstrate that multiple-mode effect and GW emission play critical roles in modeling DM production from PBHs in the early universe.
↳ astro-ph.COastro-ph.HEgr-qchep-ph+1JHEP(2025)·10 citations
34*
Effective Field Theory of Chiral Gravitational Waves
Katsuki Aoki🇯🇵 · Tomohiro Fujita🇯🇵 · Ryodai Kawaguchi🇯🇵 · Kazuki Yanagihara🇯🇵
When a (non-)Abelian gauge field acquires an isotropic background configuration during inflation, strong gravitational waves (GWs) with parity-violating polarization, known as chiral GWs, can be produced in addition to the intrinsic unpolarized GWs. However, previous studies have analyzed individual models, leaving the generality of this phenomenon unclear. To perform a model-independent analysis, we construct an effective field theory (EFT) of chiral GWs by extending the EFT of inflation and incorporating gauge fields. The resulting action unifies inflationary models with a $S U (2)$ gauge field, such as chromo-natural inflation and gauge-flation, and ones with a triplet of $U (1)$ gauge fields, systematically encompassing all possible GW production mechanisms consistent with the symmetry breaking induced by the gauge field background. We find that chiral GWs are generically and inevitably produced, provided that the effective energy density of the background gauge field is positive and the gauge kinetic function is not fine-tuned to a specific time dependence. This EFT offers a useful foundation for future phenomenological studies as well as for deepening our theoretical understanding of chiral GWs.
↳ astro-ph.COgr-qchep-phhep-thJCAP(2026)·10 citations
35*
Search for high energy 5.5 MeV solar axions with the complete Borexino dataset
Borexino Collaboration
A search for solar axions and axion-like particles produced in the $p + d \to^{3} He + A (5.5 MeV)$ reaction was performed using the complete dataset of the Borexino detector (3995 days of measurement live-time). The following interaction processes have been considered: axion decay into two photons $(A \to 2 γ)$ , inverse Primakoff conversion on nuclei $(A + Z \to γ + Z$ ), the Compton conversion of axions to photons $(A + e \to e + γ)$ and the axio-electric effect $(A + e + Z \to e + Z$ ). Model-independent limits on axion-photon ( $g_{A γ}$ ), axion-electron ( $g_{A e}$ ), and isovector axion-nucleon ( $g_{3 A N}$ ) couplings are obtained: $∣ g_{A γ} \times g_{3 A N} ∣ \leq 2.3 \times 1 0^{- 11} GeV^{- 1}$ and $∣ g_{A e} \times g_{3 A N} ∣ \leq 1.9 \times 1 0^{- 13}$ at $m_{A} <$ 1 MeV (90\% c.l.). The Borexino results exclude new large regions of $g_{A γ}$ , and $g_{A e}$ coupling constants and axion masses $m_{A}$ , and leads to constraints on the products $∣ g_{A γ} \times m_{A} ∣$ and $∣ g_{A e} \times m_{A} ∣$ for the KSVZ- and the DFSZ-axion models.
↳ hep-exastro-ph.SRhep-phnucl-exEPJC(2025)·6 citations
36*
Impact of Initial-State Nuclear and Sub-Nucleon Structures on Ultra-Central Puzzle in Heavy Ion Collisions
Qi Wang🇨🇳 · Long-Gang Pang🇨🇳 · Xin-Nian Wang🇨🇳
Hydrodynamic models fail to describe the near-equal $v_{2} / v_{3}$ ratio observed in ultra-central heavy-ion collisions, despite their success in other centrality classes. This discrepancy stems from shear viscosity suppressing higher-order geometric eccentricities, resulting in underestimated $v_{3}$ when using the conventional QGP viscosity coefficient. We explore two initial-state modifications to resolve this puzzle: (1) enforcing a minimum nucleon separation distance to homogenize distributions, and (2) amplifying sub-nucleon structures to reduce initial eccentricity. Using TRENTo initial conditions and 3+1D viscous hydrodynamic model CLVisc, both approaches significantly lower geometric eccentricity, reduce required viscosity, and narrow the $v_{2}$ - $v_{3}$ gap in ultra-central collisions. Our results implicate initial-state nuclear and sub-nucleon structures as critical factors in addressing this puzzle. Resolving it would advance nuclear structure studies and improve precision in extracting QGP transport coefficients (e.g., shear viscosity), bridging microscopic nuclear features to macroscopic quark-gluon plasma properties.
↳ nucl-thhep-ph2 citations
37*
A Perturbatively Stable Non-Supersymmetric String Model with AdS Vacuum
Ignatios Antoniadis🇹🇭 · Alonzo R. Diaz Avalos🇬🇧 · Alon E. Faraggi🇬🇧
We present a construction of a perturbatively stable non-supersymmetric type II closed string model in four dimensions. It is based on a freely acting Scherk-Schwarz Z2-deformation of a supersymmetric construction which is recovered in appropriate decompactification limits. The model exhibits also the so-called misaligned supersymmetry with alternating signs for the number difference between bosons and fermions at successive mass levels. The tree-level spectrum is tachyon free for any value of the radii and moduli. At one loop level, the scalar potential has a non-supersymmetric minimum at the self-dual (free fermionic) point with negative energy, around which all tree-level massless scalars acquire positive masses. The model is thus non-supersymmetric and perturbatively stable.
↳ hep-thhep-phJHEP(2025)·6 citations
38*
Four-Fermion Deformations on Line Defects in QED $_{4}$ with Yukawas
Alessandra D'Alise🇮🇹 · Giulia Muco🇩🇰 · Francesco Sannino🇩🇰
We elucidate the dynamics induced by a Wilson Line of charge $q$ and electron charge $e$ in $QE D_{4}$ coupled to a real scalar via Yukawa interactions. We observe that there is a range of the fixed product $e^{2} q$ with $e \to 0$ and $q \to \infty$ for which four-fermion operators play a dominant role for the dynamics of the theory. We uncover the fixed-point dynamics of the theory and analyze their critical behavior.
↳ hep-thcond-mat.str-elhep-lathep-ph1 citation
39*
The shape of differential radial flow $v_{0} (p_{T})$ , not its zero-crossing, carries physical information
Somadutta Bhatta🇺🇸 · Aman Dimri🇺🇸 · Jiangyong Jia🇺🇸
Radial flow, a key collective phenomenon in heavy-ion collisions, manifests itself through event-by-event fluctuations of transverse-momentum ( $p_{T}$ ) spectra. The $p_{T}$ -differential radial flow observable, $v_{0} (p_{T})$ , was introduced to quantify local spectral-shape fluctuations, but it is unavoidably influenced by global multiplicity fluctuations. Using the HIJING model, we show that different event-activity definitions for centrality classification and different spectral normalization schemes generate a constant vertical offset in $v_{0} (p_{T})$ without altering its shape. This offset reflects the impact of residual volume/centrality fluctuations rather than genuine dynamical radial flow fluctuations. Accordingly, only the shape of $v_{0} (p_{T})$ , or equivalently its derivative $d v_{0} (p_{T}) / d p_{T}$ , carries physical information about radial-flow dynamics; its zero crossing does not. Practical implications include the need to vertically align measurements from different experiments before comparison, thereby removing normalization ambiguities when constraining QGP properties.
↳ nucl-thhep-phnucl-exNucl.Sci.Tech.(2026)·7 citations
40*
Starlight from JWST: Implications for star formation and dark matter models
John Ellis🇨🇭 · Malcolm Fairbairn🇬🇧 · Juan Urrutia🇪🇪 · Ville Vaskonen🇪🇪
We confront the star formation rate in different dark matter (DM) models with UV luminosity data from JWST up to $z ≃ 25$ and legacy data from HST. We find that a transition from a Salpeter population to top-heavy Pop-III stars is likely at $z ≃ 10$ and that beyond $z = 10 - 15$ the feedback from supernovae and active galactic nuclei is progressively reduced, so that at $z ≃ 25$ the production of stars is almost free from any feedback. We compare fuzzy and warm DM models that suppress small-scale structures with the CDM paradigm, finding that the fuzzy DM mass $> 5.6 \times 1 0^{- 22} eV$ and the warm DM mass $> 1.5 keV$ at the 95% CL. The fits of the star formation rate parametrisation do not depend strongly on the DM properties within the allowed range. We find no preference over CDM for enhanced matter perturbations associated with axion miniclusters or primordial black holes. The scale of the enhancement of the power spectrum should be $> 25 Mpc^{- 1}$ at the 95% CL, excluding axion miniclusters produced for $m_{a} < 6.6 \times 1 0^{- 17} eV$ or heavy primordial black holes that constitute a fraction $f_{PBH} > max [105 M_{⊙} / m_{PBH}, 1 0^{- 4} (m_{PBH} /1 0^{4} M_{⊙})^{- 0.09}]$ of DM.
↳ astro-ph.COastro-ph.GAhep-phAstron.Astrophys.(2025)·17 citations
41*
Neutrino flavor instabilities in a binary neutron star merger remnant: Roles of a long-lived hypermassive neutron star
Hiroki Nagakura🇯🇵 · Kohsuke Sumiyoshi🇯🇵 · Sho Fujibayashi🇯🇵 · Yuichiro Sekiguchi🇯🇵 · Masaru Shibata🇩🇪
Understanding the post-merger evolution of binary neutron star merger (BNSM) requires accurate modeling of neutrino transport and microphysics including neutrino flavor conversions. Many previous studies have suggested that fast flavor instability (FFI) and collisional flavor instability (CFI) pervade inner regions of BNSM remnant, and they could impact on fluid dynamics and r-process nucleosynthesis. In this work, we re-examine prospects of occurrences of FFI and CFI using Boltzmann neutrino transport, assuming a frozen fluid background obtained from a numerical relativity simulation of BNSM. We pay special attention to a case involving a long-lived ( $> 1$ s) hypermassive neutron star (HMNS). Apart from confirming the claim that these flavor instabilities can occur in BNSM remnants, some new insights are revealed. We identify multiple mechanisms responsible for generating electron neutrino lepton number (ELN) angular crossings, corresponding to a key indicator of FFI onset, which differ notably from those in black hole (BH) accretion disk systems. We argue that the appearance of positive chemical potential of electron-type neutrinos plays important roles on generating ELN angular crossings. For CFI, their growth rates are generally lower than FFI, but they can persistently occur in most of the accretion disk up to $\sim 1$ s. We also find that neglecting contributions of heavy-leptonic neutrinos results in overestimating growth rate and area of unstable regions of CFI. Our result suggests that FFI (CFI) tends to occur transiently (persistently) and locally (widespread in the disk), and FFI is more sensitive to the central compact object (HMNS or BH) than CFI, though more self-consistent simulations with incorporating effects of flavor conversions are needed to confirm these claims.
↳ astro-ph.HEgr-qchep-phnucl-thPRD(2025)·16 citations
42*
Future Circular Collider Feasibility Study Report: Volume 1, Physics, Experiments, Detectors
M. Benedikt (Study Leader) · F. Zimmermann (Deputy Study Leader) · B. Auchmann · W. Bartmann · J.P. Burnet · C. Carli · A. Chancé · P. Craievich · M. Giovannozzi · C. Grojean · J. Gutleber · K. Hanke and 1452 other authors
Volume 1 of the FCC Feasibility Report presents an overview of the physics case, experimental programme, and detector concepts for the Future Circular Collider (FCC). This volume outlines how FCC would address some of the most profound open questions in particle physics, from precision studies of the Higgs and EW bosons and of the top quark, to the exploration of physics beyond the Standard Model. The report reviews the experimental opportunities offered by the staged implementation of FCC, beginning with an electron-positron collider (FCC-ee), operating at several centre-of-mass energies, followed by a hadron collider (FCC-hh). Benchmark examples are given of the expected physics performance, in terms of precision and sensitivity to new phenomena, of each collider stage. Detector requirements and conceptual designs for FCC-ee experiments are discussed, as are the specific demands that the physics programme imposes on the accelerator in the domains of the calibration of the collision energy, and the interface region between the accelerator and the detector. The report also highlights advances in detector, software and computing technologies, as well as the theoretical tools /reconstruction techniques that will enable the precision measurements and discovery potential of the FCC experimental programme. This volume reflects the outcome of a global collaborative effort involving hundreds of scientists and institutions, aided by a dedicated community-building coordination, and provides a targeted assessment of the scientific opportunities and experimental foundations of the FCC programme.
↳ hep-exhep-phphysics.acc-phEPJC(2025)·269 citations
43*
Future Circular Collider Feasibility Study Report: Volume 3, Civil Engineering, Implementation and Sustainability
M. Benedikt (Study Leader) · F. Zimmermann (Deputy Study Leader) · B. Auchmann · W. Bartmann · J.P. Burnet · C. Carli · A. Chancé · P. Craievich · M. Giovannozzi · C. Grojean · J. Gutleber · K. Hanke and 1452 other authors
Volume 3 of the FCC Feasibility Report presents studies related to civil engineering, the development of a project implementation scenario, and environmental and sustainability aspects. The report details the iterative improvements made to the civil engineering concepts since 2018, taking into account subsurface conditions, accelerator and experiment requirements, and territorial considerations. It outlines a technically feasible and economically viable civil engineering configuration that serves as the baseline for detailed subsurface investigations, construction design, cost estimation, and project implementation planning. Additionally, the report highlights ongoing subsurface investigations in key areas to support the development of an improved 3D subsurface model of the region. The report describes development of the project scenario based on the 'avoid-reduce-compensate' iterative optimisation approach. The reference scenario balances optimal physics performance with territorial compatibility, implementation risks, and costs. Environmental field investigations covering almost 600 hectares of terrain - including numerous urban, economic, social, and technical aspects - confirmed the project's technical feasibility and contributed to the preparation of essential input documents for the formal project authorisation phase. The summary also highlights the initiation of public dialogue as part of the authorisation process. The results of a comprehensive socio-economic impact assessment, which included significant environmental effects, are presented. Even under the most conservative and stringent conditions, a positive benefit-cost ratio for the FCC-ee is obtained. Finally, the report provides a concise summary of the studies conducted to document the current state of the environment.
↳ physics.acc-phhep-exhep-phEur.Phys.J.ST(2025)·72 citations
44*
Future Circular Collider Feasibility Study Report: Volume 2, Accelerators, Technical Infrastructure and Safety
M. Benedikt (Study Leader) · F. Zimmermann (Deputy Study Leader) · B. Auchmann · W. Bartmann · J.P. Burnet · C. Carli · A. Chancé · P. Craievich · M. Giovannozzi · C. Grojean · J. Gutleber · K. Hanke and 1452 other authors
In response to the 2020 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) Feasibility Study was launched as an international collaboration hosted by CERN. This report describes the FCC integrated programme, which consists of two stages: an electron-positron collider (FCC-ee) in the first phase, serving as a high-luminosity Higgs, top, and electroweak factory; followed by a proton-proton collider (FCC-hh) at the energy frontier in the second phase. FCC-ee is designed to operate at four key centre-of-mass energies: the Z pole, the WW production threshold, the ZH production peak, and the top/anti-top production threshold - delivering the highest possible luminosities to four experiments. Over 15 years of operation, FCC-ee will produce more than 6 trillion Z bosons, 200 million WW pairs, nearly 3 million Higgs bosons, and 2 million top anti-top pairs. Precise energy calibration at the Z pole and WW threshold will be achieved through frequent resonant depolarisation of pilot bunches. The sequence of operation modes remains flexible. FCC-hh will operate at a centre-of-mass energy of approximately 85 TeV - nearly an order of magnitude higher than the LHC - and is designed to deliver 5 to 10 times the integrated luminosity of the HL-LHC. Its mass reach for direct discovery extends to several tens of TeV. In addition to proton-proton collisions, FCC-hh is capable of supporting ion-ion, ion-proton, and lepton-hadron collision modes. This second volume of the Feasibility Study Report presents the complete design of the FCC-ee collider, its operation and staging strategy, the full-energy booster and injector complex, required accelerator technologies, safety concepts, and technical infrastructure. It also includes the design of the FCC-hh hadron collider, development of high-field magnets, hadron injector options, and key technical systems for FCC-hh.
↳ physics.acc-phhep-exhep-phEur.Phys.J.ST(2025)·168 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.