HEP Phenomenology·hep-ph

Wed·Jul 8, 2026Wednesday·July 8, 2026

40 papers—24 primary·16 cross-listed

01
Searching for charged Higgs bosons in top decays via the $t^{*} b$ channel
Saiyad Ashanujjaman🇩🇪 · Guglielmo Coloretti🇮🇹 · Andreas Crivellin🇪🇸 · Benjamin Fuks🇫🇷 · Yeonsu Heo🇨🇭
Rare top-quark decays offer a sensitive probe of charged Higgs bosons with masses below the top mass, owing to the large $t t ˉ$ production rate at the LHC and the distinctive final states involving leptons and $b$ -jets. While existing searches target the $H^{\pm} \to τ ν$ , $cs$ , and $c b$ modes, the decay $H^{\pm} \to t b$ has been studied only for heavier charged Higgs bosons with an on-shell top quark in the final state. The low-mass off-shell channel $H^{\pm} \to t^{*} b$ therefore remains essentially unconstrained, even though it can become the dominant decay mode below the top-quark threshold owing to the large top Yukawa coupling. We study charged-Higgs production from the rare top decay $t \to H^{\pm} b$ , followed by the decay $H^{\pm} \to t^{*} b$ . Top-antitop production and decay hence give rise to a $t t ˉ b b ˉ$ -like final state, which we constrain by reinterpreting recent ATLAS fiducial measurements in dileptonic events. We obtain model-independent limits of 1.9%-2.9% on the product of branching ratios $Br (t \to H^{\pm} b) \times Br (H^{\pm} \to t^{*} b)$ for charged-Higgs masses between 110 and 165 GeV, and interpret these bounds in several two-Higgs-doublet scenarios. While dedicated searches for conventional charged-Higgs decays dominate for canonical $Z_{2}$ -symmetric models, the $t^{*} b$ reinterpretation becomes competitive near the top-quark threshold in the up-type aligned limit and provides relevant direct constraint in a top-philic scenario. In the top-specific Two-Higgs-Doublet Model, it additionally excludes a low- $tan β$ region not covered by conventional searches. These results thus establish $t t ˉ$ production with additional $b$ -jets as a complementary probe of light charged Higgs bosons and nonstandard top-quark decays, and motivate dedicated analyses by the LHC collaborations.
hep-phhep-ex0 citations
02
Constant Scaling Fails for Global Monopole Networks
Wakutaka Nakano🇯🇵 · Wen Yin🇯🇵
Global monopoles, which can also be understood as the zero-gauge-coupling limit of gauged monopoles, can form in the early Universe and evolve following a scaling network, as do other topological defects. However, only a limited number of numerical studies have investigated their scaling behavior. In this Letter, we show that the monopole number density parameter, $ξ$ , does not follow the commonly assumed constant scaling. Instead, it exhibits a logarithmic-like evolution, despite the fact that the energy of an isolated global monopole grows linearly, rather than logarithmically, with the infrared cutoff. This behavior is found using the fat-monopole prescription and is supported by a conventional fixed-core simulation. We characterize the deviation by the fractional response $γ \equiv d lo g ξ / d lo g (m_{r} / H)$ , and find $γ \sim 0.5$ for blue-tilted initial spectra. These results suggest that analytic studies based on the assumption of constant scaling should be revisited. They are also relevant to cosmological scenarios involving monopole dark matter, axion and dark-photon dark matter produced by monopole networks, monopole-induced primordial black holes, and gravitational-wave production from monopole dynamics.
hep-phastro-ph.CO1 citation
03
Precision Study of Semileptonic and Non-Leptonic $B_{c}$ Decays to $η_{c}$ and P Wave Charmonia
Aritra Biswas🇩🇪 · Soumitra Nandi🇮🇳 · Shantanu Sahoo🇮🇳
We analyse semileptonic and non-leptonic decays of the $B_{c}$ meson into P wave charmonium states. The analytic expressions for the transition form factors are taken from NRQCD, while their normalisations and shapes are constrained directly using experimental data, without introducing any additional model-dependent inputs. Using radiative decay data of $χ_{c 0}$ , $χ_{c 1}$ , and $h_{c}$ , we extract the derivatives of their radial wave functions at the origin and update the $B_{c} \to (χ_{c 0}, χ_{c 1}, h_{c})$ form factors. We present predictions for the semileptonic branching fractions, the lepton flavour universality ratios $R (χ_{c 0}) = 0.185 (3)$ , $R (χ_{c 1}) = 0.147 (26)$ , and $R (h_{c}) = 0.068 (2)$ , as well as selected non-leptonic $B_{c}$ decays and P-wave charmonium production in $e^{+} e^{-}$ annihilation and $Z$ -boson decays.
hep-phhep-ex0 citations
04
Linear Breit-Wheeler pair production in the search for axion-like particles
Thomas Rook🇬🇧 · Wei Wu🇬🇧 · Stuart P. D. Mangles🇬🇧 · Steven J. Rose🇬🇧
Assuming the existence of axion-like particles (ALPs), the standard Quantum Electrodynamics (QED) amplitudes for the linear Breit-Wheeler (BW) pair production process are shown to be supplemented by an additional ALP-mediated amplitude. We compute the coherently combined cross section and show that, for pseudoscalar ALPs, interference with QED produces an asymmetric Fano-type resonance. We propose experimental observation of the BW process with real photons as a complementary probe of MeV-scale ALPs, coupling jointly with photons and electron-positron pairs, on the basis that it occupies a kinematic region not readily accessible to other ALP search methods.
hep-phphysics.plasm-ph0 citations
05
Can blind spots save neutralino dark matter in natural supersymmetry models?
Howard Baer🇺🇸 · Vernon Barger🇺🇸 · Dibyashree Sengupta🇮🇹
Natural supersymmetry (SUSY) models remain viable even in the face of LHC Run 2 sparticle search limits. However, the LZ experiment has placed strong limits on light higgsino dark matter even when the higgsinos carry only their thermally-produced abundance, with the bulk of the dark matter composed of axions. One way out is the possibility of WIMP direct detection blind spots where cancellations in direct detection (DD) couplings lead to tiny DD rates. We examine natural SUSY models with mu <0 and \mu >0 but find that the surviving blind spots all lie in the unnatural region where the superpotential |mu | parameter is much greater than the weak scale gaugino masses; the few natural candidates are excluded by LHC soft-dilepton searches and by the measured Higgs mass. Within NUHM2/NUHM3-type gravity-mediated models with positive gaugino masses and assuming a thermally produced neutralino fractional abundance, direct-detection blind spots do not rescue stable light higgsino dark matter in the electroweak-natural region. Thus, within this framework, stable light higgsino dark matter is disfavored, although special circumstances like large entropy dilution of all relics is still possible. This points to SUSY models with {\it unstable} light higgsinos as perhaps the preferred alternative.
hep-ph0 citations
06
Compactness, mass spectra, and strong stability of singly heavy tetraquarks
Wen-Nian Liu🇨🇳 · Kai-Kai Zhang🇨🇳 · Duo-Jie jia🇨🇳 · Fu-Quan Dou🇨🇳
We propose a Coulomb-like parameterization in terms of bag radius of the short-range chromo-electric interaction between heavy quarks and strange quarks within the framework of the MIT bag model for hadrons including multiquark systems and re-examine mass spectra of doubly and fully heavy baryons self-consistently and variationally. Building upon this, we apply this approach to systematically investigate the mass spectra and $S$ -wave strong decay stability of singly heavy tetraquark systems, including $n Q n ˉ n ˉ$ , $n Q s ˉ n ˉ$ , $Q s n ˉ n ˉ$ , $s Q s ˉ n ˉ$ , and $s Q s ˉ s ˉ$ (with $Q = c, b$ ). Choosing the bag confinement energy as a compactness criterion, the bag radius is shown to be close to the confinement uplimit of the radius, $R_{c} = 5.615 GeV^{- 1}$ , for the compact singly charmed systems,and for these systems some high-spin states are unlikely to form compact structures, while several others do exhibit potential for compactnessNotably, computation indicates that the state $T_{n c s ˉ n ˉ} (0^{+}, 2.925)$ emerges as a compact tetraquark with relatively large strong decay width, a plausible candidate of the observed tetrquark $T_{c s ˉ 0}^{a} (2900)$ .
hep-ph2 citations
07
Separating energy scales in hadron scattering
S.M. Troshin🇷🇺 · N.E. Tyurin🇷🇺
We discuss energy scales in soft hadron scattering and possibility of their separation: the one relevant to the region where the total cross--sections increase starts and another one related to the asymptotic region. The latter scale is most sensitive to the unitarity effects and the former one --- to the gross features of absorption of the initial wave due to multiparticle production. Transition from the shadow to reflective scattering sets a relation between the two energy scales.
hep-phhep-ex0 citations
08
Anisotropic electron scattering and Migdal effect in semiconductor detectors
Aula Al-Adulrazzaq🇫🇮 · Paolo Settembri🇨🇭 · Sebastian Sassi🇫🇮 · Federico Giannessi🇮🇹 · Gianni Profeta🇮🇹 · Matti Heikinheimo🇫🇮 · Kimmo Tuominen🇫🇮
Cryogenic semiconductor detectors are widely used in dark matter direct detection. Electronic excitations in these materials can be caused either by direct dark matter electron scattering events, or indirectly via dark matter nuclear scattering events. For nuclear scattering of light dark matter, the event rate is enhanced due to an inelastic process known as the Migdal effect. Both the electron recoils and the Migdal effect in semiconductors depend on the dielectric function of the target material via the so-called energy loss function (ELF). In the standard approach found in the literature, the ELF is approximated as isotropic to simplify the calculation of the event rate. We introduce a practical method for computing the event rate for a general anisotropic ELF. We find that the daily modulation of the Migdal rate arises solely due to the quadrupole component of the ELF, whereas in electron scattering all spherical harmonic components affect the rate. We apply the formalism to study the daily modulation in silicon and gallium arsenide detectors.
hep-ph0 citations
09
Radiative decays of $X (3872)$ within $D D ˉ^{*}$ molecular framework
Hao-Dong Cai🇨🇳 · Run-Hao Chen🇨🇳 · Yuan-Jun Gao🇨🇳 · Zhao-Sai Jia🇨🇳 · Gang Li🇨🇳 · Shi-Dong Liu🇨🇳
Within the framework of nonrelativistic effective field theory, we calculate the radiative decay width of the process $X (3872) \to D ˉ D γ$ while taking into account the $D D ˉ$ final-state interactions. In this work, the $X (3872)$ , with the spin-parity quantum numbers $J^{P C} = 1^{++}$ , is treated as a $D^{*} D ˉ + c.c.$ bound state comprising equal proportions of neutral and charged components. Our numerical calculations predict the tree-level partial decay width of approximately $11.0$ keV for the decay process $X (3872) \to D ˉ^{0} D^{0} γ$ , while the partial width for $X (3872) \to D^{-} D^{+} γ$ is less than $1.0$ keV. It is found that the $D D ˉ$ rescattering effect enhances the tree-level width of $X (3872) \to D ˉ^{0} D^{0} γ$ by $6%$ . In contrast, the rescattering effect makes a suppression to the charged channel $X (3872) \to D^{-} D^{+} γ$ by roughly $38%$ . We expect that the present predictions based on the molecular picture of the $X (3872)$ can be tested by future experiments.
hep-ph0 citations
10
A resonance-aware MC@NLO QCD+EW-matched calculation of lepton-pair production
Lois Flower🇬🇧 · Joanne Roper🇬🇧 · Marek Schönherr🇬🇧
As we approach HL-LHC, there is a growing need for increased precision in theoretical predictions so that meaningful comparisons with experimental data can be made. It is no longer sufficient to include only QCD higher-order corrections, with EW effects becoming increasingly important. Even at hadron colliders, QED radiation provides large corrections to some observables. In this paper, we present the first automated matching of NLO QCD+EW to an interleaved QCD+QED parton shower using the MC@NLO matching method in the Catani-Seymour dipole formalism. When considering such a matched parton shower, the presence of resonances can lead to spurious higher order terms, originating in the recoil assignment, within the standard dipole construction. We therefore develop a resonance-aware modification to the MC@NLO algorithm that can be applied to QCD- and QED-singlet resonances. We validate our interleaved matching and its resonance-aware modification against fixed-order NLO QCD+EW and pure MC@NLO QCD combined with YFS resummation. Finally, we present resonance-aware MC@NLO QCD+EW predictions for Drell-Yan lepton pair production, a vital precision process at hadron colliders.
hep-ph0 citations
11
A Quantitative Framework of Nonperturbative QCD from Topological Vacuum with Application to Parton Structures
Wei-Yang Liu🇺🇸
This dissertation develops a quantitative framework that provides a physical picture for non-perturbative QCD based on the topological structure of the QCD vacuum. By integrating out the ultraviolet degrees of freedom, the infrared gluon configurations are modeled as a liquid ensemble of instantons and anti-instantons, which induce effective interactions among quarks. This framework captures the origin of trace and axial anomalies through the infrared distributions of QCD and dynamically breaks chiral symmetry. More specifically, this framework can be formulated in two ways: in one, we construct a statistical ensemble with weights defined by the instanton action and Dirac determinant, while in the other we formulate an effective field theory (EFT) by rewriting the determinant as effective quark interactions. By reformulating the EFT on the light front, we explicitly construct the light-front wave functions and calculate various parton observables in linear factorization. We further embed the framework into transverse momentum dependent factorization and establish a vacuum origin for rapidity evolution by computing the soft functions. We also extend this approach to various form factors in light hadrons, including scalar, pseudoscalar, and energy-momentum tensor (EMT), as well as higher-twist color force and multigluon correlations, with applications to hadron mass and spin decomposition, near-threshold quarkonium production, and strong CP problem, highlighting the importance of the vacuum origin in hadron structures. Overall, this work demonstrates that the QCD vacuum provides a quantitatively crucial description of hadronic structure from low to moderate resolution, bridging nonperturbative vacuum physics with partonic phenomenology.
hep-phhep-th0 citations
12
ggxy: Fast and flexible NLO QCD corrections to gluon-initiated processes
Daniel Stremmer🇩🇪
We present the C++ library ggxy, which can be used for the fast and flexible calculation of partonic and hadronic cross sections to gluon-initiated top-mediated processes such as $g g \to H H$ , as well as the newly derived processes $g g \to Z H$ and $g g \to Z Z$ , at NLO QCD including full top-quark mass dependence. The two-loop virtual amplitudes are implemented using analytical approximations in different kinematic regions, while all other parts of the calculation are exact. This implementation allows to freely modify all input parameters, such as the top-quark mass and its renormalization scheme and the masses of the external $Z$ /Higgs bosons. In addition, ggxy has been interfaced to Powheg, which allows the matching to parton showers.
hep-phhep-ex0 citations
13
Radiative Breaking of Two-Zero Neutrino Mass Minors: Revisiting the $U (1)_{L_{μ} - L_{τ}}$ Model
Masahiro Ibe🇯🇵 · Jun Miyamoto🇯🇵 · Satoshi Shirai🇯🇵
The two-zero minor structure predicted by flavor symmetries is usually discussed as a tree-level relation among low-energy neutrino parameters. We point out that this relation can be significantly modified by radiative corrections even when the two-zero minor structure is enforced by an underlying symmetry at tree level. As a concrete example, we analyze the minimal $U (1)_{L_{μ} - L_{τ}}$ model and compute the universal one-loop threshold corrections associated with the type-I seesaw sector. These corrections generate flavor-dependent contributions to the Weinberg operator and violate the exact two-zero minor conditions once the $U (1)_{L_{μ} - L_{τ}}$ symmetry is spontaneously broken. This effect relaxes the tree-level lower bound on the total neutrino mass and thereby weakens the tension between the model and cosmological neutrino-mass constraints.
hep-ph0 citations
14
Non-Unitarity Effects and Fake CP Violation in Neutrino Oscillation Experiments
Pratima Singh🇮🇳 · Alina Naqvi🇮🇳 · Suhani Yadav🇮🇳 · R.B.Singh🇮🇳 · Jyotsna Singh🇮🇳
Future long-baseline neutrino oscillation experiments aim to establish leptonic CP violation and determine the neutrino mass ordering with unprecedented precision. However, these measurements can be significantly affected by possible deviations from the unitarity of the PMNS mixing matrix, which introduce additional CP-violating phases capable of generating fake CP-violating signals. We investigate the impact of non-unitary leptonic mixing on CP-violation and mass-ordering measurements at DUNE and Hyper-Kamiokande using GLoBES simulations with a custom non-unitary probability engine. We analyze the energy dependence of the neutrino--antineutrino CP asymmetry, quantify the fake-to-genuine CP asymmetry ratio, evaluate the CP violation discovery sensitivity, and study the hierarchy--CP--non-unitarity degeneracies in the $(δ_{C P}, ϕ_{21})$ parameter space. We demonstrate that non-unitary mixing can generate sizeable CP asymmetries even for CP-conserving values of the standard Dirac phase, thereby mimicking genuine leptonic CP violation. While the fake contribution remains below $5%$ of the genuine signal near each experiment's oscillation maximum, it exceeds the genuine signal in specific intermediate energy windows ( $\sim 130%$ at $1.5$ -- $1.6$ ~GeV), demonstrating that fake CP violation can dominate over the genuine contribution in these regions. The combined DUNE and Hyper-Kamiokande analysis reduces the allowed $(δ_{C P}, φ_{21})$ parameter space by a factor of $7$ at $1 σ$ and $\sim 16$ at $2 σ$ -- $3 σ$ , substantially suppressing the degeneracy that neither experiment resolves individually and providing a robust strategy for distinguishing genuine from fake CP violation while improving sensitivity to the neutrino mass ordering.
hep-ph0 citations
15
Quantum decoherence: a study applied to quarkonium-like bound states in strongly interacting matter
Gabriele Coci🇮🇹 · Salvatore Plumari🇮🇹 · Giuseppe Falci🇮🇹
We study the quantum decoherence of a bound state interacting with a reservoir of strongly interacting matter within the framework of open quantum systems. The bound state is modeled as a quantum harmonic oscillator whose parameters are tuned to reproduce the root-mean-square radius of $J /Ψ$ particle. The surrounding medium, representing the many degrees of freedom of strongly interacting matter, acts as an environment that induces dissipation and decoherence through system-reservoir coupling. By analyzing the time evolution of the reduced density matrix, we quantify the loss of quantum coherence and its dependence on medium properties. Subsequently, we extend the model by introducing a time dependence in the system-thermal bath coupling, thereby simulating a temperature evolution similar to that occurring during the expansion of a fireball in the central region of heavy-ion collisions. We find that a temperature evolution has a relevant impact on the way the system loses coherence through the coupling with the expanding medium. Finally, we estimate the impact of the time-dependent temperature on the decoherence process, also analyzing a scenario that includes viscous effects without finding a significant change with respect to ideal hydrodynamical evolution.
hep-phnucl-thquant-ph0 citations
16
Vector-Meson Spin Alignment from Anisotropic Quark or Hadron Coalescence
Wen-Bo Dong🇨🇳 · Xin-Li Sheng🇮🇹 · Yi-Liang Yin🇨🇳 · Dirk H. Rischke🇩🇪 · Qun Wang🇨🇳
The distribution of particles is highly anisotropic in the initial stage of a heavy-ion collision. In this paper we demonstrate that this anisotropy induces a sizable effect on the spin alignment of vector mesons. We study two different production mechanisms for $ϕ$ and $K^{* 0}$ mesons, on one hand the coalescence of quarks and on the other that of pseudoscalar mesons. In the quark-coalescence picture where $ϕ$ and $K^{* 0}$ are produced via a bare vector coupling to quarks, a negative $δ ρ_{00}^{y}$ of order $1 0^{- 3}$ is observed. In contrast, when $ϕ$ and $K^{* 0}$ are produced via quark coalescence with a vertex with spin-orbit coupling, or when they are produced via pseudoscalar-meson coalescence, a positive $δ ρ_{00}^{y}$ emerges. In all cases, the magnitude of the spin alignment is directly proportional to the degree of anisotropy. The sign difference between the cases provides a possibility to clarify the production mechanism for vector mesons.
hep-ph0 citations
17
Understanding the near-threshold structures in $e^{+} e^{-}$ annihilation from a unified $N N ˉ$ -interaction perspective
Teng Ji🇩🇪 · Ulf-G. Meißner🇩🇪
Near-threshold structures have been observed in the cross sections for $e^{+} e^{-} \to p p ˉ$ , $e^{+} e^{-} \to n n ˉ$ and several non-baryonic final states in the vicinity of the $N N ˉ$ thresholds. We investigate whether these structures can be understood as manifestations of a common $N N ˉ$ final-state interaction. The strong $N N ˉ$ interaction is taken from the chiral EFT description of the coupled $^{3} S_{1}$ - $^{3} D_{1}$ system constrained by low-energy $N N ˉ$ scattering data. With this interaction fixed, the $p p ˉ$ and $n n ˉ$ cross sections are described by fitting only short-distance electromagnetic production sources, which are assumed to vary slowly over the near-threshold region. The resulting $N N ˉ$ production amplitudes are then used as input for five inelastic hadronic channels. A simultaneous description of the near-threshold cross sections is obtained, indicating that the observed structures can be consistently interpreted as consequences of the same underlying $N N ˉ$ dynamics, without introducing separate narrow resonances in individual channels.
hep-phhep-ex1 citation
18
Polyakov Loops Tame Phase Transitions
Lisa Biermann🇨🇭 · Joydeep Chakrabortty🇮🇳 · Christoph Englert🇬🇧
We estimate the impact of Polyakov loop (PL) contributions on electroweak phase transitions (PTs). We show that the PL, which is unavoidable in thermal gauge field theory, tends to tame thermal contributions, thereby softening electroweak PTs and affecting bubble dynamics, nucleation, and the related gravitational-wave spectrum. Including this non-perturbative contribution in perturbative approaches results in a thermal effective potential that disfavours first-order PTs over either second-order PTs or smooth cross-overs. This feature is universal for both fermionic and bosonic contributions to the effective potential.
hep-phcond-mat.stat-mechhep-lathep-th1 citation
19
Flux-integrated inclusive and pionless cross sections for charged-current neutrino scattering off $^{40} Ar$ at energies available in the MicroBooNE experiment
A. V. Butkevich🇷🇺 · S. V. Luchuk🇷🇺
In this work, we analyze the flux-integrated inclusive and pionless differential cross sections for neutrino scattering off argon. The cross sections are calculated using the relativistic distorted-wave impulse approximation (RDWIA), taking into account the contribution of the two-particle-two-hole (2p-2h) meson-exchange currents (MEC). We find that the measured single- and double-differential cross sections can be well described within the experimental uncertainties using this approach. We also compare the differential cross sections for pionless neutrino scattering on carbon and argon, measured with the Booster Neutrino Beam flux in the MiniBooNE and MicroBooNE experiments, to study nuclear effects in these nuclei.
hep-ph0 citations
20
Role of the $Σ (1430) (1/ 2^{-})$ in the $J / ψ \to Λ Λ ˉ π^{0}$ reaction
Yu-Shan Ren🇨🇳 · Wen-Tao Lyu🇨🇳 · Eulogio Oset🇪🇸
We study the $J / ψ \to Λ ˉ Λ π^{0}$ reaction, an isospin violating reaction, by looking at the trios of baryon-antibaryon-pseudoscalar meson that conform a singlet of $SU (3)$ in the $u, d, s$ quarks. These terms conserve isospin; however, once the final-state interactions of meson-baryon and meson-antibaryon are taken into account, isospin is violated due to the different masses of particles within the same isospin multiplets. Since the reaction is tied to the interaction of particles, only resonances that are dynamically generated by these interactions show up in the reaction. In this sense, our approach produces the $Σ (1430) (1/ 2^{-})$ state, but not the $Σ (1385) (3/ 2^{+})$ . Comparing with the BESIII data we observe that, within the limited statistics of the experiment, the data show a structure {around $M_{π Λ} = 1430$ MeV} that is reproduced by the theory, and no signal is seen for the $Σ (1385) (3/ 2^{+})$ as the theory predicts. We call for a future update of the experiment once better statistics become available.
hep-ph0 citations
21
$K X (3872)$ interaction and correlation function
Jing Song🇨🇳 · Pedro Brandao🇧🇷 · Eulogio Oset🇯🇵
We investigate the $K X (3872)$ interaction and the corresponding correlation function, assuming the $X (3872)$ to be a molecular state of $D D ˉ^{*}$ and $D^{*} D ˉ$ with isospin $I = 0$ and positive $C$ -parity. The interaction is treated within the fixed-center approximation (FCA) to the Faddeev equations, in which the $X (3872)$ is taken as a cluster of its constituents and the kaon interacts with the $D^{*}$ and $D$ components. The three-body scattering amplitude is evaluated using the Fixed Center Approximation (FCA) to the Faddeev equations, improved by taking the FCA amplitude as an optical potential which is later unitarized by means of the Lippmann-Schwinger equation. We find a narrow resonant structure about 50~MeV below the $K^{+} X (3872)$ threshold with a width of approximately 1~MeV, and determine the $K X (3872)$ scattering length $a = (0.39 - i 0.00)$ ~fm and effective range $r_{0} = (1.16 - i 1.66)$ ~fm. The corresponding correlation function is evaluated and shows a clear deviation from unity at low momenta, characteristic of a strongly attractive interaction leading to a bound state. These predictions are tied to the molecular nature of the $X (3872)$ and can be measured experimentally via measurements of the $K X (3872)$ correlation function and three-body invariant mass distributions.
hep-ph1 citation
22
Dispersive estimation of the LO hadronic contribution to the muon $g - 2$ : fitting incompatible $e^{+} e^{-}$ data
V.V. Bryzgalov🇷🇺 · O.V. Zenin🇷🇺
Using an up-to-date compilation of $σ_{tot} (e^{+} e^{-} \to ha d r o n s)$ data we estimated the LO hadronic contribution to the muon anomalous magnetic moment, $a_{μ} (ha d, L O)$ . Incompatibilities between $σ_{tot} (e^{+} e^{-} \to ha d r o n s)$ measurements by independent experiments are mitigated by extra systematic uncertainties estimated using as a guideline a requirement of uniformity of $χ^{2}$ distribution over degrees of freedom in joint fits of $σ_{tot}$ . Tensions in the $e^{+} e^{-}$ input data translate into an expanded uncertainty of the $a_{μ} (ha d, L O) = (697.7 \pm 9.8_{e^{+} e^{-}} \pm 3. 6_{sy s}) \times 1 0^{- 10}$ . Given this, we obtain the SM prediction for the muon anomaly $a_{μ}^{SM} = 11659185.5 (10.6) \times 1 0^{- 10}$ , below the experimental world average $a_{μ}^{exp}$ at $2 σ$ level.
hep-ph0 citations
23
Interplay of CPT-Violating and CPT-Conserving Lorentz Invariance Violation at DUNE
Priyankush Deka🇮🇳 · Arnab Sarker🇮🇳 · Moon Moon Devi🇮🇳 · Sushant K. Raut🇮🇳
We present a study of Lorentz invariance violation (LIV) in neutrino oscillations, with primary emphasis on the interplay between CPT-violating and CPT-conserving Standard Model Extension (SME) coefficients. We find that $a_{ee}$ and $a_{τ τ}$ dominate among the diagonal LIV coefficients, whereas $a_{e μ}$ and $a_{e τ}$ provide the most significant off-diagonal contributions. In contrast, the corresponding $c_{α β}$ coefficients have comparatively sub-leading effects. Taking DUNE as a representative long-baseline experiment, we show that the sensitivity to CP violation is modified by LIV in a parameter-specific manner. We find correlations between off-diagonal LIV parameters, and non-trivial dependence on the new phases. In absence of LIV, DUNE is expected to establish CP violation at $5 σ$ for a limited fraction of $δ_{C P}$ values. We find that the presence of $a_{ee}$ , $a_{τ τ}$ , $a_{e μ}$ and $a_{e τ}$ weakens the CP discovery potential, reducing the achievable significance to below $3 σ$ over a substantial fraction of $δ_{CP}$ . The independent impact of $c_{α β}$ terms also results in suppression, but in combination with $a_{α β}$ , they introduce degeneracies, complicating the extraction of $δ_{C P}$ . This generally results in a deterioration of CP violation sensitivities below $5 σ$ . These findings emphasize the importance of incorporating LIV effects in precision oscillation studies at upcoming long-baseline experiments.
hep-phhep-th0 citations
24
Predictions for $b$ -baryon lifetimes at NNLO-QCD
Alexander Lenz🇩🇪 · Maria Laura Piscopo🇨🇭 · Aleksey V. Rusov🇩🇪
Motivated by recent and forthcoming experimental progress, we provide updated predictions for the total decay rates of $b$ -baryons, their lifetime ratios and their lifetimes normalised to that of the $B_{d}^{0}$ meson within the framework of the heavy quark expansion (HQE). We include, for the first time, next-to-next-to-leading-order QCD corrections to the free $b$ -quark decay, which significantly reduce the theoretical uncertainties in the total decay rates. In addition, we also include, for the first time, the complete next-to-leading-order QCD corrections to the dimension-five contributions. While these corrections have only a minor effect on the total decay rates, they induce a sizeable shift in the lifetime ratios, improving the agreement between HQE predictions and experimental data. Overall, we find excellent agreement between the HQE predictions and current experimental measurements for both total decay rates and lifetime ratios within the quoted uncertainties.
hep-phhep-ex0 citations
25
Alleviating the Hubble Tension with Smooth Sign-Switching Dark Energy: Full CMB Constraints with DESI and PantheonPlus
Mariam Bouhmadi-López🇪🇸 · Hsu-Wen Chiang🇨🇳 · Beñat Ibarra-Uriondo🇪🇸
Sign-switching dark energy has recently been proposed as a minimal modification of the late-time expansion history aimed at alleviating tensions within the standard cosmological model. In this work, we investigate ECDM, a smooth realisation of this scenario, with the dark energy density gradually transitioning from a negative to a positive value. We develop a consistent formulation of the perturbation equations that remains well behaved even when the dark energy equation-of-state parameter diverges during the transition. We confront the model with a comprehensive set of cosmological observations, including cosmic microwave background measurements from Planck 2018, ACT DR6 and SPT-3G, baryon acoustic oscillation measurements from DESI DR2, Type Ia supernova distances from Pantheon+, and local Hubble constant measurement of SH0ES. The inclusion of perturbations allows us to assess the impact of the model on structure growth and CMB anisotropies, providing a more thorough test of sign-switching dark energy. Our results show that this class of models is fully compatible with current precision cosmological observations while alleviating the Hubble tension and providing a compelling modification of the late-time dynamics of the Universe.
↳ astro-ph.COgr-qchep-phhep-th4 citations
26
An inquiry into the Absence of Fermion Doubling and why the Nielsen-Ninomiya Theorem Does Not Apply to Nonlocal Quantum Field Theory
Arvin Kouroshnia🇨🇦 · J. W. Moffat🇨🇦 · E. J. Thompson🇨🇦
In this paper we will examine if nonlocal quantum field theory will suffer from the fermion doubling pathology. We find that for a nonlocal Dirac theory, that no additional fermion species are introduced. This is provided that the form factor is nonvanishing at every point. The proof follows from the invertibility of the entire-function operator, which implies that the nonlocal Dirac operator has exactly the same kernel and finite-momentum zero set as the original local Dirac operator. We will distinguish this result from the standard Nielsen-Ninomiya theorem, which applies local lattice fermions on a compact Brillouin zone. We provide a general criterion for fermion doubling, a test for genuine and false doubling, and then a test procedure for mathematical and physical fermion doubling. We then will go on to distinguish this result from finite derivative truncations, which can introduce spurious polynomial zeros. We then conclude that fermion doubling is absent in the full continuum nonlocal theory.
↳ hep-thhep-lathep-ph2 citations
27
The Fate of Black Hole-Induced Moduli Excursions in the Presence of Scalar Potentials
Karim Benakli🇫🇷 · Anna Chrysostomou🇫🇷
Large charged black holes can create macroscopic, locally weakly curved regions in which moduli take values different from their asymptotic values. We study how robust this mechanism is once the scalar has a nontrivial potential. In four-dimensional Einstein-Maxwell-dilaton theory, the massless GHS solution provides a finite exterior throat in which the scalar and the gauge coupling vary logarithmically. We develop fixed-throat diagnostics for the competition between the black hole gauge source and a scalar potential, and compare them with back-reacted exterior evolutions when needed. The relevant criterion is not the mere presence of a potential, but how its force behaves along the scalar trajectory traced by the black hole throat. Quadratic stabilizing potentials erase the throat when the Compton wavelength becomes comparable to the horizon scale. Runaway, periodic, and barrier-type potentials instead exhibit distinct failure modes controlled by their slope, sign, oscillations, or barrier distance along the GHS trajectory. A quintessence-like scalar remains effectively massless on astrophysical black hole scales, leaving the throat essentially unobstructed. If the charge belongs to a hidden sector, and if the scalar also controls visible couplings or bulk propagation, such surviving altered-modulus regions could leave phenomenological imprints in near-horizon accretion or emission.
↳ hep-thastro-ph.COgr-qchep-ph2 citations
28
A Novel Implementation of Self-Interacting Dark Matter in AREPO
Oliver Zier · Xuejian Shen🇺🇸 · Vinh Tran · Martin Rosenlyst🇬🇧 · Mark Vogelsberger🇺🇸 · Rongrong Liu🇺🇸
Self-interacting dark matter (SIDM) influences halo structure through collisional heat transport and may solve several small-scale puzzles in structure formation. SIDM creates thermalized cores in low-mass haloes, which may account for the observed cored dwarf galaxies. During late-time gravothermal core collapse, SIDM can produce dense low-mass DM haloes and substructures detected through perturbations to cold stellar streams and strong gravitational lenses. In this work, we present a new Monte-Carlo SIDM implementation in the moving-mesh code AREPO-2, designed for efficiency, scalability, and extensibility. The central feature of the implementation is a dedicated DM-only neighbour-search tree that decouples the scattering solver from gravity. This preserves compatibility with the hierarchical time integration used by AREPO-2 while leaving the optimized gravity solver unconstrained. A pairwise communication scheme between MPI tasks allows tracking multiple scattering events in a single timestep while conserving momentum and energy and maintaining parallel consistency by construction. This is complemented by a per-pair timestep criterion that significantly reduces unnecessary timestep restrictions. The implementation natively supports velocity-dependent cross-sections and inelastic interactions, while a compact interface is designed for additional SIDM physics to be implemented without knowledge of the parallelization layer. We validate the implementation for isotropic, elastic scattering using a suite of idealized and cosmological tests. We assess performance and scalability in isolated core-collapse simulations and in cosmological boxes, both DM-only and with baryons. Except during the late stages of gravothermal collapse, SIDM simulations incur only modest overhead relative to the corresponding CDM runs and are substantially faster than the previous SIDM implementation in AREPO-1.
↳ astro-ph.COastro-ph.HEhep-phhep-th1 citation
29
Deuterium-Proton Fusion in an Effective Field Theory Constructed from On-Shell Amplitudes
Tim M.P. Tait🇺🇸
Big Bang nucleosynthesis (BBN) predicts the primordial deuterium abundance to a precision now limited by the nuclear reactions that burn deuterium. For the simplest of them, proton-deuteron radiative capture, d + p -> \gamma + 3He [d(p,\gamma)3He], the precise LUNA data sit below the ab initio benchmark, and BBN reaction networks split on which to adopt. We develop an effective field theory (EFT) expanding in the finite size of the nuclei, building the amplitude with modern on-shell methods that enumerate every tree-level structure consistent with symmetries without the need for an explicit Lagrangian. A global Bayesian fit to the capture data and nuclear-theory priors returns S(0) = 0.209 +/- 0.008 eV b and traces the offset from the ab initio benchmark to a single natural-sized next-to-leading contact term (t_E1 ~ -0.15, the fractional shift of the electric-dipole amplitude) -- equivalently a ~15% lower effective 3He asymptotic normalization. We estimate the leading EFT truncation errors and identify an elastic d-p observable that would separate them. Our results suggest that amplitude methods enable systematic and complete tree-level construction and matching of EFTs for low-energy nuclear reactions.
↳ nucl-thastro-ph.COhep-phhep-th1 citation
30
Degenerate and connection-dependent cosmological sectors in f(Q,C) gravity
Ismael Ayuso🇪🇸
We investigate cosmological solutions in $f (Q, C)$ gravity formulated within symmetric teleparallel geometry, where gravitation is described by the nonmetricity scalar $Q$ and the boundary term $C$ , related to the Ricci scalar of General Relativity through $R ˚ = Q + C$ in the absence of curvature and torsion. The symmetry requirements of FLRW spacetime admit three distinct realizations of the affine connection, leading in principle to three different cosmological sectors within the same theory. We show that the connection field equations play a crucial role in determining the cosmological dynamics. In their simplest realization, these equations impose a constraint that renders the theory dynamically equivalent to $f (R ˚)$ gravity, causing the cosmological background equations associated with the three connection realizations to coincide. This defines a degenerate cosmological sector of $f (Q, C)$ gravity, in which three a priori distinct geometric constructions converge to the same cosmological dynamics. We then consider the complementary class of genuinely nonequivalent $f (Q, C)$ models, for which the choice of connection becomes physically relevant. In this regime, the connection sector introduces additional dynamical degrees of freedom and gives rise to novel cosmological phenomenology absent in $f (R ˚)$ gravity.
↳ gr-qcastro-ph.COhep-phhep-th0 citations
31
Articulating Assumptions in AI-Generated Scientific Analyses through Task Decomposition
Ahmed Hammad🇰🇷 · Mihoko Nojiri🇯🇵
Scientific results produced by LLM generated analysis code must be understandable and reproducible. However, uncertainty can arise at different stages of the process, both in the original natural language specification and in the generated implementation. As a result, even executable code may not provide a clear understanding of which quantities are being computed or which assumptions determine the final results. To address this challenge, we introduce quantity grounded semantic differencing, a multi-agent framework for analyzing and comparing scientific programs generated by LLMs. The framework assigns code generation, execution, tracing, and validation to separate agents, allowing it to reconstruct how key output quantities are produced and to identify differences between the intended analysis and the implemented code. We also introduce a module that inspects ambiguities in the initial user instruction and suggests alternative rewrites before code generation. Its modular design enables application to different scientific domains by replacing domain specific resources while preserving the same workflow. We validate the framework on representative collider physics analyses. The results demonstrate that the modular task decomposition enhances both transparency and reliability relative to the previous single prompt approach, while enabling substantially smaller models to execute the complete workflow.
↳ cs.SEhep-exhep-ph2 citations
32
Dipole ghosts and spontaneous symmetry breaking in higher-order Chern-Simons theory
Carlos M. Reyes🇨🇱 · César Riquelme🇨🇱 · Angel Sanchez🇲🇽
In this work, we investigate the emergence of dipole ghost structures in gauge theories at both the classical and quantum levels. Traditionally, dipole ghosts are introduced through an auxiliary field $χ$ satisfying $□^{2} χ = 0$ , whose presence is reflected in the appearance of double poles in the propagator. We show that such dipole ghost sectors can instead be understood as a consequence of the multiplicity of solutions of the classical equations of motion. To establish this connection, we develop a constructive method and first apply it to covariant Maxwell theory in $(2 + 1)$ dimensions, where the essential ingredients can be identified in a transparent manner. We then extend the analysis to the constrained higher-order Chern-Simons theory, demonstrating that the same mechanism gives rise to dipole ghost sectors and associated double poles in the propagator. Our results provide a unified perspective on the origin of dipole ghosts, relating them directly to the degeneracy structure of the underlying classical dynamics. As a physical application, we investigate spontaneous symmetry breaking and compute the one-loop effective potential. We show that symmetry breaking removes the degeneracy underlying the dipole ghost sector, leading to a spectrum of ordinary massive gauge excitations that determine the quantum vacuum structure of the theory.
↳ hep-thhep-ph0 citations
33
Constraints on Yukawa-type New Forces from the Lamb Shift in Muonic Hydrogen and Deuterium
Chung-Chien Huang🇹🇼 · Li-Bang Wang🇹🇼
We develop an analytical framework to constrain Yukawa-type fifth-force interactions using the Lamb shift in hydrogen and deuterium. The sixfold coordinate-space integral for the energy shift is transformed into a one-dimensional momentum-space convolution of the atomic form factor and the Yukawa potential, eliminating the need for approximations. This formulation directly incorporates empirical nuclear charge distributions through their form factors, making the implementation of experimental results straightforward. Applying this method to the latest hydrogen and deuterium spectroscopy data, we derive constraints on the coupling constant $α$ in the interaction range $λ \in [1 0^{- 4}, 1 0^{6}]$ ~fm. A resonance-like cancellation between the $2 s$ and $2 p$ orbital shifts is identified at a critical range $λ \sim 1 0^{5}$ ~fm, where the energy shift vanishes and the constraint on $α$ diverges, marking a transition between attractive and repulsive regimes. The constraints are shown to be independent of the nuclear charge distribution model. Our results indicate that the transition frequency shifts induced by such new forces lie well below current spectroscopic resolution, establishing spectroscopic precision as the primary bottleneck for probing these interactions.
↳ physics.atom-phhep-phhep-th0 citations
34
Two fluid CFL strange quark stars with scalar dark matter: critical mass and mass gap implications
J. Sedaghat🇮🇷 · G. H. Bordbar🇮🇷 · M. Haghighat🇮🇷 · S. M. Zebarjad🇮🇷
We investigate the structure of strange quark stars (SQSs) in the color--flavor--locked (CFL) phase in the presence of scalar bosonic dark matter within a two--fluid formalism employing perturbative QCD. By considering different dark matter masses and varying the pairing gap $Δ$ and {the central dark matter pressure fraction} $f_{r}$ , we analyze the impact of dark matter on the structural properties of SQSs, including the maximum gravitational mass $M_{TOV}$ , the ratio of dark matter to strange-quark-matter radii $R_{DM} / R_{SQM}$ , and the dimensionless tidal deformability $Λ$ . We further examine the compatibility of the resulting mass--radius relations with the recent NICER measurements of compact stars. Within the parameter space considered in this study, we find that $M_{TOV}$ exhibits a non-monotonic dependence on the dark matter mass, with a critical value beyond which $M_{TOV}$ decreases. We also show that some pure CFL strange quark star configurations, particularly those associated with very stiff EOSs and larger maximum masses, may not simultaneously remain compatible with the $Λ$ range inferred from GW170817 while occupying the lower mass--gap region. In contrast, the inclusion of dark matter allows two-fluid CFL strange quark star configurations to reproduce the observed properties of massive compact objects in the lower mass--gap region, such as the secondary component of GW190814, while remaining qualitatively compatible with the $Λ$ range inferred from GW170817. We note, however, that the GW170817 constraints were originally inferred within single-fluid compact-star frameworks and therefore provide only {qualitative guidance} for the present two-fluid halo configurations. Our results suggest that exotic compact-star configurations may populate part of the conventionally defined lower mass--gap region.
↳ astro-ph.HEastro-ph.SRgr-qchep-ph+1NPB(2026)·1 citation
35
Background-independent one-loop renormalization of tensor and scalar primordial spectra
Guillermo Ballesteros🇪🇸 · Jesús Gambín Egea🇪🇸 · Flavio Riccardi🇮🇹
We present a background-independent renormalization framework for one-loop primordial spectra. We apply it to two observables: the scalar-induced tensor spectrum sourced by a minimally coupled spectator field, and the scalar spectrum generated by potential self-interactions. In both cases, the UV part of the loops is isolated and, using the universal WKB behavior of the internal modes, the UV poles are extracted analytically and absorbed into local counterterms without having to specify either the background evolution or the full dynamics of the field running in the loop. This yields finite model-independent expressions for the renormalized spectra amenable to numerical analysis.
↳ hep-thastro-ph.COgr-qchep-ph0 citations
36
On stochastic realism and CP bias in diffractive dissociations
A.Y. Klimenko🇷🇺
CP bias in proton--antiproton diffractive dissociation can be viewed from several philosophical perspectives, notably stochastic realism and stochastic epistemicism. When combined with the presumption of temporal symmetry, stochastic realism suggests that the laws of physics allow the possibility of thermodynamic antisystems, although whether antisystemic characteristics can be physically realised in nature remains an open question. Here, this bias is interpreted as apparent, indicating significant non-unitary contributions and a distinction from fundamental CP violations arising from unitary Hamiltonian dynamics. Such apparent effects may arise from intrinsic stochasticity, from environmental interactions, or from interference between the two. This work investigates the relevant mechanisms and determines conditions for creating, transmitting, or screening a CP bias. In the environmental branch, an equilibrated radiation bath may transmit a CP bias from matter-dominated surroundings, although causality constraints may limit this possibility. In the intrinsic branch, the observed bias is consistent with subleading antisystemic effects required by CPT invariance. Further experiments are needed to distinguish between these mechanisms.
↳ quant-phhep-ph0 citations
37
Determination of thermodynamics from entanglement entropy in the finite-density O(N) model
Niko Jokela🇫🇮 · Aatu Rajala🇫🇮 · Tobias Rindlisbacher🇫🇮
We nonperturbatively compute Rényi entropies for strip-shaped subregions in the three-dimensional O(4) model at finite density on the lattice. By using a dual variable representation and a tailored worm algorithm, we circumvent the sign problem when sampling the grand canonical ensemble. In the limit of large subregions, we also establish a direct, quantitative relationship between the derivative of entanglement entropy with respect to the size of the entangling region and the thermal entropy density for general quantum field theories, providing a new way to study their thermodynamics. We corroborate this argument with our lattice results by demonstrating that, in the appropriate limit, the derivative of entanglement entropy satisfies the same Maxwell relation as the thermal entropy density.
↳ hep-thcond-mat.stat-mechhep-lathep-ph+11 citation
38
Compact Syzygies for Feynman Integrals from Landau Singularities
Federico Coro🇧🇪 · Pavel P. Novichkov🇧🇪 · Ben Page🇧🇪 · Qian Song🇧🇪
We discuss a recent proposal for constructing ``syzygy solutions'', which play a crucial role in integration-by-parts reductions for multi-loop scattering amplitudes. We highlight a relationship between syzygies and the leading Landau singularities of Feynman diagrams and discuss how this implies that integral relations are controlled by infrared singularities. We use this insight to systematically construct highly compact, determinantal syzygy solutions, providing an explicit, simple example at one loop. We demonstrate the power of this approach by applying it to a two-loop pentabox family relevant for the NNLO corrections to $pp \to t t H$ at the LHC.
↳ hep-thhep-ph0 citations
39
An Intermediate Scale R-axion \& the QCD Axion
James Unwin🇺🇸
An intermediate scale R-axion faces an immediate obstruction from the Dine-Festuccia-Komargodski (DFK) bound on the superpotential, $2∣ ⟨ W ⟩ ∣ \leq f_{R} F$ , since for a nearly Minkowski vacuum it typically follows that $f_{R} ≳ M_{Pl}$ . We show that this lower bound on $f_{R}$ can be relaxed in an effective construction with the scalar potential tuned near zero via a mixed $F$ - and $D$ -term uplift, leading to a metastable vacuum in which the usual Planckian- $f_{R}$ inference from the DFK argument is avoided locally. Validity of the effective field theory and metastability of the small $f_{R}$ vacuum generically both imply a relaxed bound: $f_{R} ≳ m_{3/2} M_{Pl}$ . We also highlight that if the R-symmetry has a QCD anomaly, this potentially permits the R-axion to play the role of the QCD axion. TeV-scale supersymmetry permits $f_{R} \sim 1 0^{11}$ GeV, this not only evades certain astrophysical and cosmological axion constraints, but notably lies in the window for which the observed dark matter abundance can be reproduced by the R-axion via the misalignment mechanism.
↳ hep-thhep-phJHEP(2026)·0 citations
40
Finite-Field QED Corrections to Vacuum Birefringence and Magnetar Polarization Transport
S. Abbassi🇨🇦 · F. A. Chishtie🇨🇦 · S. R. Valluri🇨🇦
We study low-energy photon propagation in a constant magnetic field within the finite-field one-loop Heisenberg--Euler framework and apply the resulting mode-dependent refractive indices to magnetar polarization transport. In a centered-dipole model, the polarization-limiting radius is unchanged to better than $1 0^{- 12}$ because mode decoupling occurs at $\sim 1 0^{2} R_{NS}$ , where $B ≪ B_{cr}$ . Near the surface, however, the weak-field Cotton--Mouton expression overestimates the accumulated birefringent phase by up to a factor $2.9$ at $1 0^{15}$ ~G. At the plasma--vacuum resonance, finite-field corrections reduce the resonance density by $32%$ and raise the adiabatic conversion energy by $14%$ for 1E~1547.0 $-$ 5408; the corresponding changes are factors $2.6$ and $1.37$ for 1RXS~J1708 $-$ 4009, and factors $9.7$ and $2.13$ for SGR~1806 $-$ 20, the latter controlled by the strong-field asymptote. The parallel-mode magnetic response remains positive and exhibits a broad maximum near $17 B_{cr}$ . Its strict $O (α)$ expansion is monotonic, indicating that the detailed position and profile of the maximum are not controlled beyond the present approximation and require higher-loop assessment. These results identify vacuum-resonance observables as the most sensitive channel for testing finite-field QED in magnetars.
↳ astro-ph.HEhep-phEPJC(2026)·0 citations

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first authorsco-authorsvia INSPIRE