HEP Phenomenology·hep-ph

Wed·Oct 7, 2026Wednesday·October 7, 2026

33 papers—25 primary·8 cross-listed

01
Relative $P$ -wave excitations of $D^{(*)} D ˉ^{(*)}$ configurations in QCD sum rules
Yi-Wei Jiang · Hua-Xing Chen · Er-Liang Cui · Ding-Kun Lian · Niu Su
We investigate the relative $P$ -wave excitations of the $D^{(*)} D ˉ^{(*)}$ systems using the QCD sum rule method. By introducing a covariant derivative between two ground-state charmed meson fields, we construct color-singlet interpolating currents to describe the relative orbital excitation between the two meson clusters. The $P$ -wave $D D ˉ$ , $D D ˉ^{*} / D^{*} D ˉ$ , and $D^{*} D ˉ^{*}$ configurations with $J^{P} = 1^{-}$ are systematically studied. Their masses are predicted to be around $3.8$ , $3.9$ , and $4.0$ - $4.1$ GeV, respectively. These values are close to the corresponding thresholds and are compatible with the structures around $X (3790)$ and $G (3900)$ , supporting their possible interpretations as $P$ -wave $D D ˉ$ and $D D ˉ^{*} / D^{*} D ˉ$ configurations, respectively. In addition, we find that the $J^{P C} = 1^{-+}$ and $1^{--}$ combinations in the $D D ˉ^{*} / D^{*} D ˉ$ sector possess identical correlation functions in the present QCD sum rule framework, leading to degenerate mass predictions for these two channels. These results indicate that relative $P$ -wave excitations of heavy meson pairs may constitute another interesting class of near-threshold hadronic configurations worthy of further experimental investigation.
hep-ph
02
$λ$ - $ρ$ mode mixing and radial Regge trajectories for triply heavy baryons $Ω_{ccc}$ and $Ω_{bbb}$ in the diquark picture
Jiao-Kai Chen · Xin-Ru Liu · Qi Liu
The mixed-mode trajectories arising from permutation-enforced $λ$ - $ρ$ mode mixing are first investigated in the diquark picture. By accounting for the internal structure and substructure of baryons, we propose an approach to construct the mixed-mode Regge trajectories for baryons composed of three identical quarks. For triply heavy baryons $Ω_{ccc}$ and $Ω_{bbb}$ , naive diquark-quark basis states without full permutation symmetrization violate the exchange symmetry required by the Pauli exclusion principle for three identical fermions; consequently, physical eigenstates arise as permutation-enforced $λ$ - $ρ$ mode admixtures. Under the minimal-mixing assumption, we explicitly perform permutation symmetrization for the $J^{P} = (3/2)^{+}$ radially-excited S-wave states and construct mixed-mode Regge trajectory formulas for these symmetrized states. Unlike triply heavy baryons $Ω_{cc b} / Ω_{c bb}$ in the fixed diquark $(cc) b / (bb) c$ picture where well-defined pure $ρ$ - and $λ$ -trajectories exist, genuine pure-mode trajectories no longer survive for $Ω_{ccc}$ and $Ω_{bbb}$ due to permutation-driven cross-mode mixing. The resulting effective radial trajectories exhibit a novel sprouting-branch-like behavior. Both the original unmixed trajectories and the mixed-mode effective trajectories exhibit behavior of $M \sim x^{2/3}$ (where $x = n_{r}, N_{r}, n_{r} + N_{r}$ ). Radially excited masses are crudely estimated via the mixed-mode Regge trajectories, which show reasonable agreement with existing theoretical predictions.
hep-ph
03
Lunar radio emission from dark photon dark matter
Ariel Arza
The dielectric surface of the Moon provides an efficient interface for the conversion of dark matter dark photons into radio waves. This work explores a novel detection strategy that aims to capture this radio emission using standard radio telescope antennas. Detailed sensitivity projections are presented that demonstrate the power of this technique. It is found that both current and future radio observatories, including large arrays such as the Atacama Large Millimeter/submillimeter Array (ALMA) and the Square Kilometer Array (SKA), as well as large single dishes like the Five-hundred-meter Aperture Spherical Telescope (FAST) and the Green Bank Telescope (GBT), can explore a substantial and previously inaccessible parameter space for these dark matter candidates.
hep-phastro-ph.COastro-ph.IM
04
Primordial black holes and scalar-induced gravitational waves in the supersymmetric 331 model from SU(6)
Imtiaz Khan · Niamat Ullah · Ali Muhammad · Mussawir Khan · G. Mustafa · Farruh Atamurotov · Ahmadjon Abdujabbarov
We study primordial black holes and scalar-induced gravitational waves in the supersymmetric 331 model based on SU(6). The inflaton continues to be the D-flat radial combination of the 331 symmetry-breaking fields Phi and Phi-bar, fields which are already accountable for the CMB branch. A gauge-invariant contribution that is localised in the Kaehler frame function causes the force in the Einstein frame to decrease over a finite range of the field and results in a temporary nonattractor phase. We calculate the supergravity potential and the radial metric, evolve the background and the Mukhanov-Sasaki modes, and assess the neutral covariant Hessian along the local region. The CMB trajectory is still in agreement with the present observational constraints while the curvature spectrum attains a value of P_zeta ~ 5.38 x 10^-3 when k ~ 1.88 x 10^13 Mpc^-1. The enhanced spectrum leads to a primordial black hole distribution with a mass comparable to that of an asteroid and to a maximum in the scalar-induced gravitational wave signal at a frequency of 3.17 x 10^-2 Hz with Omega_GW,0 h^2 ~ 9.41 x 10^-11. The local geometry also results in a clear hierarchy of sensitivities. The gravitational wave spectrum changes smoothly as one moves along nearby trajectories whereas the Gaussian tail of the primordial black hole distribution changes much more rapidly. The positive eigenvalues of the neutral transverse Hessian remain throughout the reference trajectory. A Gaussian critical collapse calculation yields a reference integrated primordial black hole fraction of near 9.08 x 10^-3, while recent nonlinear studies suggest significant corrections to the statistics of rare collapses at the scalar power achieved here.
hep-ph
05
Molecular Structure Effects in Low-Lying $P$ -wave Bottom-Strange Meson Spectrum
Wei Hao · Guan-Ying Wang · M. Atif Sultan · En Wang
Recently, the LHCb Collaboration reported a new narrow bottom-strange meson, $B_{s 0}^{*} (5700)$ with mass $M = (5698.9 \pm 1.5 \pm 0.6)$ ~MeV, width $Γ < 9.8$ ~MeV, and spin-parity $J^{P} = 0^{+}$ in the $B_{s}^{0} π^{0}$ invariant-mass spectrum. Motivated by this observation, we study the low-lying $P$ -wave $B_{s}$ mesons in a two-stage refined constituent quark model. The one-loop radiative corrections to the confinement--one-gluon exchange potential ( $α_{s}^{2}$ ) lower the whole multiplet by $25$ -- $50$ ~MeV and improve the level ordering; however, the scalar $B_{s 0}^{*}$ mass still exceeds the LHCb data by $\sim 120$ ~MeV in a purely compact picture. The inclusion of the coupled-channel dynamics is decisive: the $B K$ threshold, lying close to the scalar mass, generates a sizeable meson--meson (molecular-like) component that pulls the pole down to $\sim 5727$ ~MeV, within $30$ ~MeV of the measurement, and simultaneously suppresses the $S$ -wave phase space, naturally accounting for the anomalously narrow width. Consistent results are obtained for the $1^{+}$ $B_{s 1}$ partner, for which we predict a mass $\sim 5747$ -- $5755$ ~MeV, in agreement with the chiral-doubling scenario. The $B_{s 1}$ state is expected to be very narrow and decaying mainly through the isospin-violating $B_{s}^{*} π^{0}$ and radiative $B_{s} γ$ , $B_{s}^{*} γ$ modes, providing a clear discovery target at LHC Run~3. The $E 1$ radiative widths of the $j_{ℓ} = 1/2$ states are predicted at the $50 \sim 60$ ~keV, and the strong width of the pure $j_{ℓ} = 3/2$ state $B_{s 2}^{*} (5840)$ ( $1.5$ ~MeV) reproduces the measurement. Our results support the interpretation of $B_{s 0}^{*} (5700)$ as a near-threshold scalar with strong molecular dressing and establish the predicted $1^{+}$ $B_{s 1} (5747)$ as the decisive test of the hadronic dynamics in the $B_{s}$ sector.
hep-ph
06
Minimal cascade decay of the top quark through a new scalar
Bogdan A. Dobrescu · Max H. Fieg · Alessandro Russo
We explore a possible decay of the top quark into a new scalar $ϕ_{t}$ plus a charm quark. The decay is mediated by a dimension-5 operator that may be generated by the exchange of a heavy vectorlike quark, $χ$ , and can have a branching fraction close to a percent. In a minimal model, $ϕ_{t}$ decays due to the same operator that allows the nonstandard top decay, leading to a final state involving a $c$ jet, a $b$ jet and a $W$ boson. Hence, the top quark would undergo a nonstandard cascade decay through $ϕ_{t}$ and then through an off-shell top quark. The main nonstandard collider signal is a $t t ˉ \to c c ˉ b b ˉ W^{+} W^{-}$ process. In addition, production of the vectorlike quark at the LHC would lead to a signal of the type $χ ϕ_{t} j \to 3 c + b b ˉ W W j$ .
hep-ph
07
Monopole Catalysis from Standard Model Anomalies
Nathaniel Craig · Dan Sehayek
We study the generalized symmetries associated with Standard Model flavor and their fate in the presence of magnetic monopoles. This illuminates a striking phenomenological consequence: even when baryon and lepton number are classically conserved, the electroweak anomaly induces $Δ B = Δ L \in 3 Z$ in monopole-fermion scattering for any monopole activating the anomaly. We demonstrate this mechanism in Pati-Salam theory and trinification.
hep-phhep-th
08
Coherent versus incoherent amplification: from parametric resonance to the kinetic regime in stimulated axion decay
Clemente Smarra · Elisa Todarello
Although the spontaneous decay of axions into two photons is extremely slow on cosmological timescales, it can be strongly enhanced in environments with large bosonic occupation numbers. From a classical field perspective, stimulated axion decay is described by modified Maxwell equations. For a coherent axion background, these equations exhibit a parametric resonance characterized by a photon growth exponent $s \propto g_{aγ}$ . By contrast, a standard kinetic description, for instance based on Boltzmann equations, involves the squared matrix element of the decay process and therefore would naturally predict a characteristic rate scaling as $s \propto g_{aγ}^{2}$ . In this work, we show that these apparently different behaviors originate from the coherence properties of the axion field. Starting from an axion field with a finite momentum dispersion, we show how dephasing among its momentum modes modifies the photon instability and derive an effective evolution equation in which this effect is encoded in a kernel. For a continuous Maxwell-Boltzmann distribution of axion velocities, we obtain an implicit expression for the photon growth exponent that reproduces the two asymptotic regimes and provides an approximate description of the crossover. When amplification develops on scales shorter than the axion coherence length, the parametric resonance scaling $s \propto g_{aγ}$ is recovered, whereas in the opposite limit an effectively kinetic behavior with $s \propto g_{aγ}^{2}$ emerges. Although the detailed form of the crossover depends on the axion momentum distribution, we expect the asymptotic scaling with $g_{aγ}$ to be largely insensitive to the specific distribution assumed.
hep-phastro-ph.COhep-th
09
Magnus: neutrino oscillation probabilities for any Hermitian Hamiltonian, any number of flavors, and any matter profile
Mauricio Bustamante
Interpreting neutrino oscillation measurements requires computing the probability that a neutrino born with one flavor is detected with another. In vacuum and in matter of constant density, this probability has exact formulas. Where the density varies along the path, as in the Earth, the Sun, or a supernova, it does not. There, the usual approaches either replace the profile by constant-density steps, whose error falls only as the square of their width, or integrate the evolution equation with a general-purpose solver, which must shorten its steps to meet a tighter tolerance. Both become slow at high accuracy, yet an analysis needs the probability at many energies, directions, and parameter values. Each new experiment or model often requires writing and validating a new solver. We present Magnus, an open-source Python code that avoids these limitations. It uses the Magnus expansion, whose error falls as a high power of its step width and whose cost is set by how fast the density varies, not by how many oscillations the path holds. Magnus accepts any density profile, any number of flavors, and any Hermitian Hamiltonian, such as those of non-standard interactions, sterile neutrinos, Lorentz-invariance violation, and pseudo-Dirac neutrinos. Where a cheaper route exists, it takes it automatically. For example, where the density varies slowly, as in the Sun, it follows the instantaneous eigenstates and applies the expansion only at resonances. Besides oscillating probabilities, Magnus returns phase-averaged ones, which describe solar and astrophysical neutrinos. A typical probability takes a few milliseconds, and batched scans are one to two orders of magnitude cheaper per point. Among the public codes we compared, Magnus is the fastest at high accuracy on a varying profile. Magnus shifts the effort of studying a new experiment or model from writing a solver to specifying its physics.
hep-phastro-ph.HEhep-exhep-th+1
10
Compositeness and decay properties of the flavor partner of $D_{s 0}^{*} (2317)$
J. Sánchez-Illana · R. Molina · Pan-Pan Shi
In view of the recent experimental finding of the heavy quark flavor partner of the $D_{s 0} (2317)$ in the bottom sector, the $B_{s 0} (5700)$ , we perform the $B^{(*)} K ˉ^{(*)}$ coupled-channel calculation in the hidden-gauge formalism. By fixing the mass of the bound state generated by the $B K ˉ$ interaction with $J^{P} = 0^{+}$ to the observed state, we also predict five new states with $J^{P} = {0, 1, 2}^{+}$ in this sector. In particular, three of them have $J^{P} = 1^{+}$ and masses $5740$ , $6005$ and $6065$ MeV, respectively. In addition, we evaluate the decay width of the $B_{s 0}$ and $B_{s 1}$ states through the isospin breaking decay mode $B_{s}^{0} π^{0}$ and $B_{s}^{* 0} π^{0}$ , respectively. We find that, because these states have large binding energies with respect to the $B^{(*)} K ˉ$ threshold, the coupling to the bare component can reduce this decay width by more than half of the decay width, from $50$ keV in the purely molecular model to $10 - 20$ keV, when the $B_{s 0}$ is coupled to the bare component. We also observe that, after considering heavy-quark-spin violating contributions, the decay width for the $B_{s 1}$ becomes smaller than for the $B_{s 0}$ .
hep-phhep-exhep-lat
11
Unitarity limits on HH production from VBF mediated channels
A. Dobado · D. Domenech · M. Herrero · R. A. Morales
In this work we study the unitarity constraints on double Higgs production from Vector Boson Fusion mediated channels, specifically in $f_{1} f_{2} \to f_{3} f_{4} H_{5} H_{6}$ scattering, where $f$ refers generically to either fermion or anti-fermion, and both cases with quarks and leptons will be considered. We focus on the beyond Standard Model contributions from anomalous quartic couplings of two electroweak gauge bosons and two Higgs bosons ( $V V H H$ with $V V = W W, Z Z$ ) from effective operators containing four derivatives. These four derivative operators appear in the two most popular effective field theories, SMEFT (at canonical dimension 8) and HEFT (at chiral dimension 4), and their corresponding $V V H H$ effective vertices can be easily related for the considered processes here. The aim of this work is to derive jointly the unitarity constraints on these related effective vertices using the peculiarities of the VBF mediated channels with four particles in the final state while keeping the propagation of the internal $V V$ pairs being off-shell as it must be for these channels. We also discuss the relevance of the obtained constraints for $f_{1} f_{2} \to f_{3} f_{4} H_{5} H_{6}$ at high energy colliders.
hep-ph
12
Toward N $^{3}$ LO CT global PDF analyses: The SACOT- $χ$ scheme in DIS and DGLAP evolution at partial N $^{3}$ LO
Marco Guzzi · Yao Fu · Casey Hampson · Pavel Nadolsky · Maximiliano Ponce-Chavez · Tanishq Sharma · Keping Xie · C.-P. Yuan
We discuss three aspects of the ongoing efforts of the CTEQ--TEA group toward global parton distribution function (PDF) analyses beyond NNLO accuracy in QCD. First, we present a realization of the SACOT- $χ$ general-mass variable flavor number scheme for deep-inelastic scattering (DIS) at the partial next-to-next-to-next-to-leading order (pN $^{3}$ LO) in QCD. We numerically illustrate how this SACOT- $χ$ theory prediction captures the dependence of DIS structure functions on masses of heavy quarks with inclusion of the available $O (α_{s}^{3})$ contributions. Second, we discuss a preliminary pN $^{3}$ LO CT25 fit that implements such contributions. Third, we extend the Candia algorithm for solving DGLAP evolution equations for unpolarized parton distribution functions (PDFs) in $x$ space to N $^{3}$ LO in QCD. The algorithm is based on logarithmic expansions of the solution and can be extended to all orders in QCD. An expansion equivalent to the exact DGLAP solution at N $^{3}$ LO is presented in the non-singlet sector. We show results for approximate N $^{3}$ LO PDFs evolved using the most recent approximations to the 4-loop splitting functions in QCD.
hep-ph
13
Probing axion-like particles through associated gauge-boson recoil and polarization at the LHC
Amandip De · Monoranjan Guchait · Arnab Roy
Axion-like particles (ALPs) appear in many well-motivated extensions of the Standard Model (SM) and can exhibit characteristic interactions with electroweak gauge bosons ( $V = W^{\pm} / Z$ ) through higher-dimensional operators. We explore the production of ALPs ( $a$ ) in association with $V$ at the HL-LHC, with $s = 14 TeV$ and an integrated luminosity of $L = 3 ab^{- 1}$ . We study the process $pp \to V a$ , with $a \to γ γ$ , for ALP masses in the range $20 GeV \leq m_{a} \leq 200 GeV$ . This analysis extends existing associated-production searches by exploiting characteristic recoil and polarization features induced by the momentum-dependent $V - V - a$ interaction. Using both cut-based selections and an XGBoost multivariate analysis, we demonstrate that these observables provide robust discrimination against SM backgrounds beyond the diphoton mass peak, improving the sensitivity to electroweak ALP couplings to $C_{W W} ≳ 5.6 \times 1 0^{- 3} TeV^{- 1}$ and $C_{B B} ≳ 2.8 \times 1 0^{- 2} TeV^{- 1}$ . We further show that, if a resonance peak is observed in data, the same observables can help distinguish an ALP-like signal from a Higgs-like spin--0 state of the same mass.
hep-phhep-ex
14
Spectator Dark Matter and the Higgs Portal
Stephen E. Henrich · Yann Mambrini · Keith A. Olive
Light scalar spectators generically acquire large stochastic fluctuations during inflation, which can lead to a catastrophic overproduction of dark matter if the resulting primordial condensate survives until late times. We show that this inflationary memory can be sufficiently suppressed by an extremely feeble Higgs portal interaction with sub-freeze-in couplings ( $1 0^{- 28} ≲ λ_{H S} ≲ 1 0^{- 9}$ ). The Higgs portal induces both a radiative self-interaction for the spectator as well as a thermal mass, both of which can lead to early onset of oscillations and efficient redshifting of the condensate's energy density without thermalizing the spectator or destroying the condensate. The Higgs portal also alters the stochastic equilibrium distribution of the spectator fluctuations, leading to a suppression of the field variance relative to an isolated spectator. We include a detailed treatment of the possibility that inflation may not have lasted sufficiently long for the spectator to reach its equilibrium distribution of fluctuations, finding the major constraint on such a scenario to come from isocurvature, which requires $N ≳ 1 0^{10}$ e-folds. We also consider the addition of a non-minimal gravitational coupling, which extends the parameter space significantly. This model generally favors sub-GeV light dark matter ( $0.1 eV ≲ m_{S} ≲ 10 GeV$ ) and in the absence of non-minimal gravity it also favors low reheating temperatures. While this mechanism can supply the entire relic abundance with sub-freeze-in portal couplings, it also naturally provides a suppressed initial condition for standard Higgs portal freeze-in.
hep-phastro-ph.CO
15
Born-Oppenheimer Effective Field Theory as a unified framework for all the XYZ exotics
Tommaso Scirpa
We discuss some recent applications of the Born-Oppenheimer effective field theory (BOEFT) formalism, directly derived from QCD and grounded in scale separation and symmetries, to hadronic systems containing two heavy quarks. This formalism provides a unified description of both ordinary and exotic quarkonium states (i.e., hybrids, tetraquarks, pentaquarks, ...) dynamics via coupled Schrödinger equations, whose potentials are computable on the lattice. The aim is to unveil the elusive pattern of the XYZ exotic hadrons. Here, we apply the BOEFT formalism to the $χ_{c 1} (3872)$ , $T_{cc} (3875)^{+}$ , and their bottom counterparts. Moreover, we assess the threshold effects on the quarkonium spectrum and discuss the inclusive production cross section for $χ_{c 1} (3872)$ .
hep-phhep-exhep-latnucl-th
16
Neutral Pseudoscalar Mesons, Hadron Light-by-Light Scattering, and the Muon Anomalous Magnetic Moment
Cong-Cong Ye · Yu-Chen Hu · Minghui Ding · Craig D. Roberts
Continuum Schwinger function methods\linebreak (CSM) are used to provide estimates of pseudoscalar meson pole contributions - $P = π^{0}$ , $η$ , $η^{'}$ , $η_{c}$ , $η_{b}$ - to the muon anomalous magnetic moment. The analysis framework is benchmarked via successful applications to an array of other meson and nucleon properties. It uses the leading order CSM truncation, augmented by a parametrisation of non-Abelian anomaly effects, to deliver an internally consistent treatment of all the pseudoscalar--two-photon transition form factors required to complete such a calculation. Employing those form factor predictions, the following results are obtained (units $1 0^{- 11}$ ): $a_{μ}^{π^{0}} + a_{μ}^{η} + a_{μ}^{η^{'}} = 84.3 (0.8)$ - a value lower than some other contemporary estimates; $a_{μ}^{η_{c}} = 0.82 (0.04)$ ; and a value of $a_{μ}^{η_{b}}$ that is negligible. The total contribution is $\sum_{P} a_{μ}^{P} = 85.1 (0.8) /1 0^{11}$ . Our analysis suggests that this pole contribution to $a_{μ}$ is still not known with precision better than 5\%.
hep-phhep-exhep-latnucl-ex+1
17
Fractal phase structure of QCD under imaginary rotation
Rin Takada
We show that in hot QCD rotating at an imaginary angular velocity $Ω_{I}$ , the angular velocity selects not only the temperature of the bulk but whether charge conjugation $C$ is broken there. For QCD at temperature $T$ and imaginary quark chemical potential $θ$ , with $Ω_{I} /2 π = p / q$ in lowest terms, the bulk far from the rotation axis is in the same thermal equilibrium state as nonrotating QCD at temperature $T / q$ and imaginary quark chemical potential $θ^{'} = q θ + π (p + q + 1)$ ; this follows from the Euclidean boundary conditions and locality alone, and holds nonperturbatively. Consequently, even at zero quark chemical potential, the bulk is placed at the Roberge-Weiss (RW) point whenever $p$ and $q$ are both odd, and $C$ is spontaneously broken there for $T > q T_{RW}$ , with $T_{RW}$ the RW endpoint temperature. The bulks at $Ω_{I} = 2 π /3$ and $4 π /3$ , for example, are both at temperature $T /3$ , yet only the former can break $C$ . The set of imaginary angular velocities at which $C$ is broken has a fractal structure: raising $T$ adds rationals of ever larger denominator. At irrational $Ω_{I} /2 π$ the bulk corresponds to zero-temperature QCD at any $T$ and remains confined.
hep-phhep-th
18
Fully charmed tetraquarks on the Lattice with controlled errors
Zhenyu Zhang · Bing-Nan Lu · Qian Wang · Qiang Zhao
We introduce the lattice quark potential model (LQPM), which discretizes the nonrelativistic quark potential model on a periodic cubic lattice and diagonalizes the resulting many-body Hamiltonian exactly. Unlike variational approaches, which provide only upper bounds on the energy, LQPM removes this variational bias, and its remaining finite-volume uncertainty is removed by extrapolation. Formulated directly in coordinate space, the method is indifferent to the specific form of the potential and accommodates arbitrary interactions, such as including three-body forces and spin-orbit and tensor couplings, that are difficult to treat in conventional few-body approaches. As a benchmark, the charmonium and $Ω_{ccc}$ spectra are reproduced within a few MeV of experiment. For the fully charmed tetraquark $cc c ˉ c ˉ$ , we obtain a $J^{P} = 0^{+}$ ground state at $5934.8 (13) MeV$ , $33.2 (13) MeV$ below the $η_{c} η_{c}$ threshold, unambiguously identified as a deeply bound tetraquark whose existence is robust against the choice of potential. Such a state can decay into two dileption pairs $2 (e^{+} e^{-})$ via $J / ψ e^{+} e^{-}$ , with significance similar to $X (6400)$ , or about one order of magnitude smaller. Lying below the lowest strong-decay channel, it can decay only through electromagnetic and weak interactions. Our results establish exact lattice diagonalization as a controlled, systematically improvable, and broadly applicable route to multiquark spectroscopy, providing a quantitative benchmark for the strong interaction and valuable guidance for future experimental searches for exotic hadrons.
hep-phhep-lat
19
Safety of dynamical SUSY breaking and gaugino condensation in models of spontaneous CP violation
Norimi Yokozaki
Solving the strong CP problem with spontaneous CP violation (SCPV) in SUSY requires that the constant term of the superpotential and the SUSY-breaking F-term be real to high accuracy. When both are generated dynamically, by gaugino condensation and by dynamical SUSY breaking (DSB), their phases need not vanish even if every theta-angle vanishes and every coupling is real; e.g., the multivalued non-perturbative superpotential may sit on a branch with a complex phase. In fact, gaugino condensation, in pure SUSY Yang-Mills theory and in its Affleck-Dine-Seiberg generalization, is safe only for N_c - N_f in {1,2} (N_c = 2 for pure SYM); otherwise the phase of the constant term reaches the gluino mass through anomaly mediation. The SUSY-breaking F-term is the main source of the MSSM soft masses, including the gluino mass, so its phase reaches theta-bar as well. In the framework of global SUSY, the 3-2 model introduces no phase. The ISS model is safe for non-degenerate quark masses in that sector; in the degenerate (or nearly degenerate) limit, however, a complex vacuum orientation can generate an O(1) phase. The IYIT model can generate a purely imaginary F-term: for roughly half of the real Yukawa parameter space, the meson VEV is purely imaginary and CP is spontaneously broken. In all three, the vacuum of the field coupled to the messengers is aligned with the constant term, so a complex constant term generates a strong CP phase through a second route, separate from anomaly mediation.
hep-phhep-th
20
Formation of Supermassive Black Hole Seeds from Vacuum-Dependent Thermal Dark Matter
Masahiro Kawasaki · Jie Sheng · Tsutomu T. Yanagida
The origin of supermassive black holes, especially those already present at high redshift, remains an open problem. We propose that their seeds are primordial black holes formed from rare overdense regions of conventional thermal DM. A spectator scalar with two degenerate vacua gives the DM different masses, and hence different freeze-out abundances, in the two vacua. Inflationary fluctuations populate the vacuum containing the heavier relic only in exponentially rare patches. As the Universe cools, the density contrast of these patches grows sufficiently large for the patches to collapse into PBHs after horizon re-entry. We derive the resulting PBH mass function and show that it is sharply concentrated near a lower cutoff while reproducing the mass scale and abundance required for SMBH seeds. Since the overdensities originate from a rare, non-Gaussian population rather than from an enhancement of nearly Gaussian primordial curvature perturbations, the usual CMB spectral-distortion constraint does not directly apply. The construction also correlates the seed population with the dark-sector spectrum and the inflation scale, providing complementary avenues for testing the scenario.
hep-ph
21
Axion Pyramid
Chan-Gyung Park · Dahee Lee · Hyerim Noh · Jai-chan Hwang
A pronounced pyramid-shaped enhancement in the axion density power spectrum induced by the QCD phase transition is identified. The enhancement occurs near the horizon scale at the transition, with a characteristic comoving length scale comparable to the size of the Solar System, and amplifies the axion density perturbation by factors exceeding $3.5 \times 1 0^{13}$ relative to the CDM case. Under the hilltop initial condition, coupling to radiation triggers this enhancement. The initial condition is related to the axion mass, suggesting that observation of the axion pyramid in cosmology may constrain the QCD axion mass.
hep-phastro-ph.COgr-qchep-th
22
The neutrino magnetic moment and supernovae with strong magnetic fields
Clément Ehrhardt · Maria Cristina Volpe · Miguel Ángel Aloy · Martin Obergaulinger
Despite several decades of searches, the neutrino magnetic moment remains unknown. If it is large, the neutrino evolution can be affected by its coupling to strong magnetic fields like the ones present in at least some core-collapse supernovae. We explore these effects for Majorana neutrinos. We first discuss a schematic model often employed and show the impact of resonant spin-flavor precession on the neutrino signal for a future galactic supernova. Then, we consider detailed simulations of a neutrino-driven supernova with 17 $M_{⊙}$ leaving a neutron star and a magnetorotational supernova with 26 $M_{⊙}$ with a black-hole remnant. We present predictions for the supernova neutrino fluxes and the event rates in presence of a non-zero neutrino magnetic moment, for the running JUNO and upcoming Hyper-Kamiokande experiments. Our results show a significant impact for transition magnetic moments of $1 0^{- 14} μ_{B}$ during the neutronization burst and the accretion phase for the neutrino driven supernova, and as small as $1 0^{- 15} μ_{B}$ at the early times for the magnetorotational supernova.
hep-phastro-ph.HE
23
Comparison of pair-source and correlation-function based Lévy analyses in Ar+Sc system at SPS energies
Barnabás Pórfy
Non-Gaussian features in femtoscopic observables have been observed in high-energy collisions, yet their origin remains not fully understood. This study focuses on the phenomenological approach to femtoscopy, going beyond the Gaussian approximation by utilizing Lévy-stable source distributions. Using UrQMD simulations, three-dimensional analyses of pion sources are done in central Ar+Sc collisions, and the extracted parameters are studied as functions of transverse mass and collision energy. This analysis contributes to a hadronic baseline motivated by past and future research work in femtoscopy at the NA61/SHINE experiment. A direct methodological comparison is presented between parameters extracted from the projections of three-dimensional pair-source distribution and those obtained from the three-dimensional correlation function, reconstructed via Fast Fourier Transform.
hep-phnucl-th
24
Flavor decoherence and washout timing in nonthermal leptogenesis after inflation
Boliang Yu · Ruixin Zhou
We investigate why changing the heavy-neutrino mass hierarchy can reverse the baryon asymmetry in nonthermal leptogenesis after hilltop inflation. Along the mass trajectory studied here, lowering the mass of the lighter state, $N_1$, reverses the final asymmetry while leaving the dominant injection from $N_2$ decays nearly unchanged. The mass change primarily delays $N_1$ washout relative to electron--muon flavor decoherence; at fixed source and background, translating the washout history while preserving its shape and integrated strength reproduces more than 99\% of the yield changes from the nonthermal $N_2$ source at two physical target masses. Decomposing the $N_2$ CP source shows that the projector-aligned component remains positive under both washout histories, whereas the initially trace-free component reverses its propagated contribution and accounts for about 99.7\% of the timing contrast in the fixed-source comparison. Rapid damping of $e\mu$ flavor coherence largely removes this contrast, while rapid chemical equilibration does not. Later washout therefore acts on a more decohered flavor state, reducing the positive $e\mu$ contribution and allowing negative diagonal contributions to determine the final sign. At a mass recomputed to reproduce the observed baryon yield, a 10\% increase of the muon collision operator reverses the sign in a fixed-input sensitivity test.
hep-phastro-ph.CO
25
Gravitational Waves and Nambu-Goldstone Bosons from Infrared-Finite Cosmic Strings
Hajime Fukuda · Shuailiang Ge · Keisuke Harigaya
Skyrmion lines and semi-local strings are examples of infrared-finite cosmic strings that arise in theories with spontaneously broken global symmetries. Unlike global $U (1)$ strings, they do not support the long-range Nambu-Goldstone boson (NGB) profile responsible for a logarithmically infrared-divergent string tension. We argue that NGB emission from their low-frequency oscillations is strongly suppressed. Consequently, their gravitational-wave signals may be comparable to those from local strings.
hep-phastro-ph.COgr-qchep-th
26
The quasinormal modes of Kerr-Newman black holes: a separated approach
Kyriakos Destounis · Vitor Cardoso · Peter Hintz
We compute Kerr-Newman quasinormal modes using a recently found exact separation of the gravitoelectric perturbation equations. For each spin-label $ς = \pm 1$ , a matrix angular ordinary differential equation and a scalar second-order radial ordinary differential equation define a joint spectral problem for the complex frequency $ω$ and separation constant $λ$ . We solve this problem by imposing regularity at the angular poles, ingoing behavior at the event horizon, and outgoing behavior at infinity. We benchmark the numerical code built to solve the separated equations, and the resulting frequencies, against recently published spectral calculations of the coupled system. Comparisons with those results yield absolute differences of order $1 0^{- 10}$ to $1 0^{- 5}$ , depending on the BH parameters and overtone number. We also find numerical hints of spin-label isospectrality in both the electromagnetic-led and gravitational-led sectors of fundamental quasinormal modes, even at near-extremal Kerr-Newman configurations. These results provide numerical evidence that the separated equations reproduce Kerr-Newman quasinormal frequencies and offer a practical route to exploring the ringdown of rotating, charged black holes.
↳ gr-qchep-phhep-th
27
The Back-to-Back Plateau of the Energy-Energy Correlator from Weak to Strong Coupling
Hao Chen · Ian Moult · Bo Wang · Hua Xing Zhu
The back-to-back limit of the energy-energy correlator (EEC) exhibits a finite plateau, capturing the evolution from perturbative soft-collinear radiation at weak coupling to string dynamics at strong coupling. At weak coupling, we resum its leading and next-to-leading-power logarithms through N $^{3}$ LL in $N = 4$ SYM, including non-planar contributions. Combining this weak-coupling endpoint with bootstrap and strong-coupling data, we construct an interpolation for the plateau height from weak to strong coupling. The calculation uses a human-in-the-loop agentic workflow.
↳ hep-thhep-ph
28
The QCD phase diagram and critical end point at finite magnetic field from holography with neural networks
Shaojie Liu · Yehong Zhang · Hui Liu · Xuanmin Cao
We study the magnetic-field-driven critical end point (CEP) of the QCD thermal transition at zero baryon chemical potential using a five-dimensional Einstein--Maxwell--dilaton (EMD) model. We calibrate the model to lattice entropy at zero and finite magnetic fields using a neural-network formulation of holographic radial evolution. As the magnetic field increases, the thermal transition changes from a crossover to a first-order transition. The merger of temperature turning points, a divergent specific heat, and a vanishing squared sound speed identify $(e B_{c}, T_{c}) ≃ (7.22 GeV^{2}, 95.9 MeV)$ . The transition-region inflection of $s / T^{3}$ defines the crossover temperature, while an equal-pressure Maxwell construction determines the first-order coexistence line. The two lines meet at the CEP. The change of transition order agrees qualitatively with lattice results. The phase boundary is a prediction of the calibrated model.
↳ hep-thhep-ph
29
Occam's Razor and a Three-Family Ultralight Fermionic Dark Matter Model
Fabian Hernandez-Gutierrez · Juan Barranco
Inspired by the three generations in the Standard Model, we propose that dark matter particles are simply three non-interacting ultralight fermions. This model is tested at galactic scales with the SPARC catalog of rotational velocity curves. This is done by modeling the dark matter halo as the self-gravitating configuration of three gravitationally coupled fermion species. This configuration is capable of forming more complex rotational curves which gives it flexibility to describe more complex and diverse morphologies of galaxy rotation curves. The core of the halos will be described by degenerate fermions and the transitions from a degenerate core to a non-degenerate halo will be described by either a perfect-fluid-like halo or a NFW density profile. In order to construct the priors of the three-fermion model, first we performed a single-fermion analysis and obtained three characteristic mass regions around 20, 40, and 65-70 eV, for both halo types. It is found that the three-component fermion model improves the goodness of fit for 94.9\% of the galaxies considered. To estimate if the additional parameters are favored despite the added complexity by the corresponding improvement in the fit, the information criteria of AICc and BIC were computed and we found that more than $50%$ of the galaxies analyzed prefer the three-component fermion model over a single fermion model. The three-fermion model is particularly favored for galaxies with larger radial extent and more complex rotation curves. The multicomponent fermionic dark sector is able to describe a large diversity of rotation curves while maintaining characteristic fermion mass scales across the galaxy sample.
↳ astro-ph.GAhep-ph
30
Mass as pairing: an explicit Majorana mass on half of a generation does not seesaw in symmetric mass generation
Piotr S. Topa
A fermion mass pairs a field with a partner of conjugate charge: elementary (Higgs-Dirac), self-conjugate (seesaw) or a three-fermion composite (symmetric mass generation, SMG). We give half of a Spin(10)-like generation an explicit Majorana mass in a four-dimensional SMG model and ask what the other half does in a phase with no condensate. With the source on, every mass-type term of the unsourced half averages to zero under the symmetry group of the sourced action, so a light mass term, and a seesaw's light-heavy mixing, requires a spontaneously broken symmetry; exact on the lattice and a general proposition. The source is colour-democratic (a Delta_R-type mass on every flavour's right-handed taste doublet); the single-nu_R split lies outside the positivity class used but inside the symmetry statement. Measured up to 8^4: (i) in the symmetric-gap phase, with the source screened to at most 1.1% of free, the unsourced half's single-fermion readout stays at 0.3% of free while its pair susceptibility rises from 0.2% to 1.2-1.7% at h=2; on like mode sets it falls with the volume, on (4^4,8^4) no inequivalent light mass channel grows faster than free, and symmetry breaking is not resolved at L<=8; (ii) at the critical point the explicit mass collapses the critical sigma channel and moves the light half toward free as a saturating crossover, not a power law; direction tests (MIXED by their pre-registered letter) are consistent with a critical coupling rising with the mass; y_c(h) is not located. Pole versus zero of the light propagator at p->0 is not measured. The outcomes are readings after pre-registered tests that mostly returned no verdict. Also: no first-order signature of the merged transition at L<=8, a Z_4-odd response handed to a lattice composite, and flavour democracy of the positivity class. Every claim has an evidence class and a runnable check.
↳ hep-lathep-phhep-th
31
Reheating surface volume renormalization and eternal inflation under broken scale invariance
Min-Seok Seo
Recently, Cotler, Ivo, and Maldacena have shown that under scale invariance, eternal inflation is interpreted as a failure of the reheating surface volume renormalization due to an ill-defined scaling dimension. Meanwhile, observations suggest that scale invariance is slightly broken, which is parametrized by deviation of the spectral index from unity, $ε = n_{s} - 1$ . Motivated by this, we study how the scale invariance breaking effect modifies the no-eternal inflation condition as the renormalizability of the reheating surface volume. For this purpose, we adopt two independent approaches: investigating the behavior of the normal ordered reheating surface volume operator under a shift of the curvature perturbation, and analyzing the coarse-graining structure to obtain the scaling dimension. Both approaches commonly reveal that as long as $ε$ is negative, which is consistent with observations, the fractal structure of the reheating surface volume breaks down at macroscopic scale, moderating the no-eternal inflation condition.
↳ hep-thgr-qchep-ph
32
Stochastic Bubble Completion in de Sitter Space: Power Spectrum, Bispectrum, and Infrared Moment Hierarchies
Hyukjung Kim · Alp Kagan Ozmen · Heeseung Zoe
Stochastic bubble nucleation makes the local completion time of a first-order phase transition a random spatial field. We study its power spectrum and equilateral bispectrum in Minkowski and de Sitter backgrounds, with particular emphasis on the infrared consequences of a finite transition duration. In an eternally extended de Sitter history, rare bubbles nucleated in the remote past generate an ancient-bubble tail that produces a hierarchy of infrared-sensitive spatial moments. For the two-point function, the first finite- $k$ correction becomes tail sensitive at $H / β = 1/5$ , while the leading moment becomes singular at $H / β = 1/3$ . The corresponding three-point thresholds are $H / β = 1/8$ and $1/6$ , showing that the bispectrum is more infrared sensitive than the power spectrum. For any finite starting time, however, the ancient-bubble tail is cut off, all spatial moments remain finite, and the strict infrared spectra recover the analytic white-noise limits $P_{τ} \propto k^{3}$ and $B_{τ}^{eq} \propto k^{6}$ . The eternal-background thresholds instead control the duration dependence of the moment coefficients and the crossover into an intermediate tail-sensitive regime, in agreement with our numerical calculations. We further show that temporal localization of the nucleation history provides a smooth regulator of the ancient-bubble tail and restores the same analytic infrared limits. These results establish a general first-arrival framework for completion-time fluctuations and clarify how de Sitter expansion can generate distinct power-spectrum and bispectrum infrared hierarchies relevant to curvature perturbations and non-Gaussianity.
↳ astro-ph.COgr-qchep-phhep-th
33
Evolution of neutrino distributions under repeated electron scattering
Jens Chluba · Bryce Cyr · Michiru Uwabo-Niibo · Masahide Yamaguchi
We study the energy redistribution of neutrinos by repeated elastic scattering with an isotropic thermal bath of free electrons. Starting from the relevant Boltzmann collision integral, we formulate the evolution equations in terms of the neutrino--electron redistribution kernel derived in our companion work. The scattering kernel formulation retains recoil, relativistic kinematics and Pauli blocking, while reducing the calculation to a one-dimensional integral in the outgoing neutrino energy. To gain a better analytic understanding, we derive the corresponding Fokker--Planck (FP) limit of the collision operator in two independent ways and contrast it with the Kompaneets equation for photons. This shows that the different energy dependence of the weak cross section changes the drift and diffusion operators which causes the high-energy part of a neutrino distribution to evolve much faster than its low-energy part. We discuss the fermionic analogues of temperature-, chemical-potential- and $y$ -type spectral distortions, and give approximate analytic solutions to the FP equation in several limiting cases. We also derive the analytic expressions for the relativistic scattering operator when Doppler terms dominate, allowing us to compute the relativistic Sunyaev-Zeldovich equivalent for neutrinos in the inefficient scattering limit. We compare these expressions to the full numerical result based on the detailed collision term. Finally, we set up conservative numerical schemes for both the FP equation and the scattering kernel, generalizing previous codes developed for studying the repeated Compton scattering of photons by relativistic electrons. Controlled line-injection experiments then illustrate when the diffusion approximation is accurate and where the non-locality of the redistribution kernel remains essential.
↳ astro-ph.COastro-ph.HEhep-ph