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Yong-Hui Lin

Publications and source records attributed to Yong-Hui Lin.

At least 19 recordsLinked to original sources
arXiv2026

Nucleon electromagnetic form-factors in a minimal Gari-Kr\"umpelmann model including the explicit two-pion continuum

The Gari--Kr\"umpelmann (GK) model provided one of the first semiphenomenological descriptions of the electromagnetic nucleon form-factors over a wide range of momentum transfer. It combined vector-meson dominance at low and intermediate momentum transfer with perturbative-QCD constraints at large momentum transfer. The present work extends this framework by including the dispersive two-pion continuum explicitly in the isovector channel. The two-pion contribution is taken from modern dispersive analyses and embedded into the intrinsic high-$Q^2$ structure of the GK ansatz. The physical $\rho$ dynamics is then interpreted as part of the correlated two-pion spectral function. The direct coupling terms remain essential for the transition to the asymptotic regime. This gives a cleaner separation between long-range continuum dynamics, coherent vector-meson contributions, and direct quark-current dynamics. With just 5 parameters, we can describe the large body on form-factor data and differential cross sections from electron-proton scattering in the space-like region.

nucl-th↗
arXiv2025

Short-range production of three bottom mesons

Previous investigations of the three-body dynamics of $B$ mesons have shown that no Efimov effect arises in systems composed of three $B$ and $B^*$ mesons. This implies that the properties of such three-body systems can be described reliably within nonrelativistic effective field theory (NREFT) with short-range interactions using only two-body input, as three-body forces are strongly suppressed. In this work, we present leading-order predictions for the three-body point production rates of systems consisting of three $B$ and $B^*$ mesons. These predictions provide a novel way to experimentally probe the $B^{(*)}$-$\bar{B}^{(*)}$ interactions, which play a crucial role in the hadronic-molecule interpretation of the $T_{b\bar{b}1}(10610)$ and $T_{b\bar{b}1}(10650)$ states. Moreover, they provide a way to test the approximate conformal symmetry predicted for such systems at low energies experimentally.

hep-ph↗
arXiv2025

Towards the LHCb pentaquark modes in the single-charm sector

The mass spectrum of $\Lambda_c$ baryon family is investigated within the $DN$-$D^*N$ coupled-channel framework using two phenomenological approaches for the low-energy $D^{(*)} N$ interactions: the heavy quark effective theory and the flavor-symmetry-constrained effective Lagrangian method. It is shown that the LHCb pentaquark states have direct analogs in the $\Lambda_c$ family. Specifically, $\Lambda_c(2765)$, $\Lambda_c(2910)$, and $\Lambda_c(2940)$ mirror the patterns of $P_{c\bar{c}}(4312)$, $P_{c\bar{c}}(4440)$, and $P_{c\bar{c}}(4457)$, respectively. These mirror pentaquark modes offer valuable insights into the quantum numbers of the two heavy $P_{c\bar{c}}$ states, which remain experimentally undetermined. Further exploration of such correlations among exotic hadronic states across different flavor sectors will be crucial for developing a comprehensive theoretical understanding of the modern hadron spectrum.

hep-ph↗
arXiv2025

Model-independent mass determination of near-threshold states from short-range production

We propose a novel observable for the precision measurements of a wide class of near-threshold dimer states: the short-range production rate of a dimer--spectator two-body system, composed of the given near-threshold state and one of its constituents. Within the framework of nonrelativistic effective field theory, these production rates exhibit characteristic line shapes for the specific partial wave and reach a model-independent minimum. This feature enables a precise extraction of their masses from experimental data, provided that the line shape can be resolved with sufficient accuracy. Applying this novel method to both the $T_{b\bar{b}1}(10610)B$ and $T_{b\bar{b}1}(10650)B^*$ systems allows for a precise determination of the binding energy $\delta$ of the $T_{b\bar{b}1}(10610)$ and $T_{b\bar{b}1}(10650)$ via the relation of $\delta=-{E_{\text{dip}}^{\text{exp}}}/{0.1983}$ once the respective dip position $E_{\text{dip}}^{\text{exp}}$ is experimentally identified.

hep-ph↗
arXiv2025

Exploring Efimov states in $D^*D^*D^*$ and $DD^*D^*$ three-body systems

The Efimov effect is an intriguing three-body quantum phenomenon. Searching for Efimov states within the realms of nuclear and hadronic physics presents a challenge due to the inherent inability of natural physical systems to exhibit adjustable two-body scattering lengths. In this study, we examine the potential existence of Efimov states in the $D^*D^*D^*$ and $DD^*D^*$ three-hadron systems. Utilizing a pionless effective field theory framework, we determine that the presence of Efimov states in the spectrum of the $D^*D^*D^*$ system is contingent upon the existence of an $(I,J)=(1,2)$ $D^*D^*$ two-body bound system. If only the $T_{cc}^+$ and its heavy quark spin partner $T_{cc}^{*+}$ exist while there is no near-threshold pole in all other $S$-wave $D^{(*)}D^*$ scattering amplitudes, no Efimov effect is expected in the $D^{(*)}D^*D^*$ systems.

hep-ph↗
arXiv2024

Baryon Form Factors

We review the status of baryon form factors with a special focus on the nucleon electromagnetic form factors which are known best. First, we give an introduction into the dispersive analyses and emphasize the role of unitarity and analyticity in the construction of the isoscalar and isovector spectral functions. Second, we present the state of the art in our understanding of nucleon form factors and radii including reliable uncertainty estimates from bootstrap and Bayesian methods. Third, we discuss the physics of the time-like form factors and point out further issues to be addressed in this framework. Finally, we review the status of hyperon form factors and comment on the pion cloud.

hep-ph↗
arXiv2024

The Proton Charge Radius from Dimuon Photoproduction off the Proton

We investigate the feasibility of measuring the proton charge radius through dimuon photoproduction off a proton target. Our findings indicate that the Bethe-Heitler mechanism, which dominates at small momentum transfers, allows for an extraction of the proton electromagnetic form factors in the extremely low $Q^2$ region below $10^{-3}$ GeV$^2$ in the spacelike region, when the incident photon beam energy exceeds several hundred MeV. The optimal kinematical region and a sensitivity study of the proton charge radius from dimuon photoproduction are presented. Such a measurement is expected to provide an alternative to the elastic muon-proton scattering measurements such as MUSE at PSI and AMBER at CERN.

hep-ph↗
arXiv2023

Method for measuring the charge radii of charged hyperons from the time-like region

We propose a novel method for measuring the charge radii of charged stable hadrons, with which the first measurement of the charge radii of the $\Sigma^+$ and the $\Xi^-$ is foreseen. The method explores the facts that the Dalitz decay $\psi(2S) \to Y\bar{Y}e^+e^-$ contains the hyperon form factors and the lowest measurable four-momentum transfer squared can be as low as $\sim 4m_e^2= 1.05\times10^{-6}\,{\rm GeV^2}$ in the time-like region. We identify a kinematic region where the hyperon form factors are essential and propose a method for subtracting the background from the data. It is estimated that the hyperon charge radii can be measured to a precision of about {0.2~fm} with the BES\Rom{3} experiment and one order of magnitude better at the future Super $\tau$-Charm Facility. Moreover, the same method can be used to measure the charge radius of the proton, which provides an independent cross-check on the extraction of proton radius from elastic $ep$ scattering or leptonic hydrogen spectroscopy.

hep-ph↗
arXiv2023

Isospin-conserving hadronic decay of the ${D_{s1}(2460)}$ into ${D_s\pi^+\pi^-}$

The internal structure of the charm-strange mesons $D_{s0}^*(2317)$ and $D_{s1}(2460)$ are subject of intensive studies. Their widths are small because they decay dominantly through isospin-breaking hadronic channels $D_{s0}^*(2317)^+\to D_s^+\pi^0$ and $D_{s1}(2460)^+\to D_s^{*+}\pi^0$. The $D_{s1}(2460)$ can also decay into the hadronic final states $D_s^+\pi\pi$, conserving isospin. In that case there is, however, a strong suppression from phase space. We study the transition $D_{s1}(2460)^+\to D_s^+\pi^+\pi^-$ in the scenario that the $D_{s1}(2460)$ is a $D^*K$ hadronic molecule. The $\pi\pi$ final state interaction is taken into account through dispersion relations. We find that the ratio of the partial widths of the $\Gamma(D_{s1}(2460)^+\to D_s^+\pi^+\pi^-)/\Gamma(D_{s1}(2460)^+\to D_s^{*+}\pi^0)$ obtained in the molecular picture is consistent with the existing experimental measurement. More interestingly, we demonstrate that the $\pi^+\pi^-$ invariant mass distribution shows a double bump structure, which can be used to disentangle the hadronic molecular picture from the compact state picture for the $D_{s1}(2460)^+$. Predictions on the $B_{s1}^0\to B_s^0\pi^+\pi^-$ are also made.

hep-ph↗
arXiv2022

Dispersion-theoretical analysis of the electromagnetic form factors of the $\Lambda$ hyperon

The electromagnetic form factors of the $\Lambda$ hyperon in the time-like region are determined precisely through a dispersion-theoretical analysis of the world data for the cross section of the annihilation process $e^+e^-\to \bar{\Lambda}{\Lambda}$. The spectral function is represented by a superposition of narrow and broad vector meson poles. We test different scenarios for the spectral function and obtain a good description of the world data in the time-like region. The uncertainties in the extracted form factors are estimated by means of the bootstrap sampling method. The analytical continuation of the form factors to the space-like region introduces large errors due to the lack of data. When the electric $\Lambda$ radius from chiral perturbation theory is taken as a constraint, the magnetic radius is predicted as $r_M = 0.681 \pm 0.002$ fm. We also extract various vector meson to baryon coupling constants.

hep-ph↗
arXiv2022

Precision calculation of the recoil--finite-size correction for the hyperfine splitting in muonic and electronic hydrogen

We present a high-precision calculation of the recoil--finite-size correction to the hyperfine splitting (HFS) in muonic and electronic hydrogen based on nucleon electromagnetic form factors obtained from dispersion theory. This will help guide the upcoming searches of the HFS transition in muonic hydrogen, and will allow a precise determination of the polarizability and Zemach radius contributions when this transition is found.

nucl-th↗
arXiv2022

The electromagnetic Sigma-to-Lambda transition form factors with coupled-channel effects in the space-like region

Using dispersion theory, the electromagnetic Sigma-to-Lambda transition form factors are expressed as the product of the pion electromagnetic form factor and the $\Sigma\bar{\Lambda}\to\pi\pi$ scattering amplitudes with the latter estimated from SU(3) chiral perturbation theory including the baryon decuplet as explicit degrees of freedom. The contribution of the $K\bar{K}$ channel is also taken into account and the $\pi\pi$-$K\bar{K}$ coupled-channel effect is included by means of a two-channel Muskhelishvili-Omn\`{e}s representation. It is found that the electric transition form factor shows a significant shift after the inclusion of the $K\bar{K}$ channel, while the magnetic transition form factor is only weakly affected. However, the $K\bar{K}$ effect on the electric form factor is obscured by the undetermined coupling $h_A$ in the three-flavor chiral Lagrangian. The error bands of the Sigma-to-Lambda transition form factors from the uncertainties of the couplings and low-energy constant in three-flavor chiral perturbation theory are estimated by a bootstrap sampling method.

hep-ph↗
arXiv2022

Proton charge radius from a dispersive analysis of the latest space-like $e$-$p$ scattering data

We present a dispersion theoretical analysis of recent date from electron-proton scattering. This allows for a high-precision extraction of the electric and magnetic radius of the proton, $r_E = (0.839\pm 0.002{}^{+0.002}_{-0.003})$~fm and $r_M = (0.846\pm 0.001{}^{+0.001}_{-0.005})$~fm, where the first error refers to the statistical type estimated from the bootstrap method, and the second one refers to the systematic uncertainty related to the underlying spectral functions.

hep-ph↗
arXiv2022

Proton charge radius from a dispersive analysis of the experimental data over the space- and time-like regions

We present a dispersion theoretical analysis of the experimental data on the electromagnetic form factors of the nucleon covering both the space- and time-like regions. The nucleon form factors over the full range of momentum transfers and the nucleon radius are extracted with high precision. The statistical uncertainties of the extracted form factors and radius are estimated using the bootstrap method, while systematic errors are determined from variations of the spectral functions. For the proton charge radius, we find $r_E^p = 0.840^{+0.003}_{-0.002}{}^{+0.002}_{-0.002}$~fm, in line with previous analyses of spacelike data alone and also the muonic Lamb shift determination.

hep-ph↗
arXiv2022

Radiative corrections to elastic muon-proton scattering at low momentum transfers

We systematically calculate the radiative corrections of order $\alpha/\pi$ to elastic muon-proton scattering at low momentum transfers. These include vacuum polarization, photon-loop form factors of the muon and the proton, two-photon exchange corrections and soft photon radiation. In particular, we discuss these corrections for the kinematics of the upcomimg AMBER experiment with a $100\,$GeV muon beam energy. It is found that for the ratio to the Born cross section, only the minor terms from the photon-loop form factors of the proton and two-photon exchange depend on the proton structure predetermined by the strong interactions. Since a prominent role among the radiative corrections is played by soft photon radiation, the calculation of the bremsstrahlung process $\mu p \to\mu p \gamma$ should be extended beyond the soft photon approximation and tailored to the specific experimental conditions.

hep-ph↗
arXiv2022

Interpretation of the $\eta_1(1855)$ as a $K\bar K_1(1400)+$ c.c. molecule

An exotic state with $J^{PC}=1^{-+}$, denoted by $\eta_1(1855)$, was observed by BESIII collaboration recently in $J/\psi \to \gamma \eta\eta'$. The fact that its mass is just below the threshold of $K\bar K_1(1400)$ stimulates us to investigate whether this exotic state can be interpreted as a $K\bar K_1(1400)+$ c.c { molecule or not}. Using the one boson exchange model, we show that it is possible for $K\bar K_1(1400)$ with $J^{PC}=1^{-+}$ to bind together by taking the momentum cutoff $\Lambda\gtrsim 2$ GeV and yield the same binding energy as the experimental value when $\Lambda\approx 2.5$ GeV. In this molecular picture, the predicted branch ratio $\mathrm{Br}(\eta_1(1855)\to\eta\eta') \approx 15\%$ is consistent with the experimental results, which again supports the molecular explanation of $\eta_1(1855)$. Relevant systems, namely $K\bar K_1(1400)$ with $J^{PC}=1^{--}$ and $K\bar K_1(1270)$ with $J^{PC}=1^{-\pm}$, are also investigated, some of which can be searched for in the future experiments.

hep-ph↗
arXiv2021

Differential Cross Section Predictions for PRad-II from Dispersion Theory

We predict the differential cross sections for $e^-p$ and $e^+p$ elastic scattering in the PRad-\Rom{2} energy region. The prediction is based on form factors obtained in our previous high-precision analysis of space- and time-like data from dispersion theory and different sets of two-photon exchange corrections. We investigate the sensitivity of the cross sections to two-photon exchange effects and find that the differences between model calculations and phenomenological extractions of the two-photon corrections can not be resolved if the uncertainty in the form factors is taken into account.

hep-ph↗