arXiv subjects

En Wang

Publications and source records attributed to En Wang.

At least 19 recordsLinked to original sources

arXiv2026

Roles of $f_0(980)$ and $a_0(980)$ in the process $Λ_c^+ \to pK_S^0K_S^0$: a clean probe of the $K\bar K$ final-state interaction

Based on the Belle measurement of $Λ_c^+ \to pK_S^0K_S^0$, we study the contributions of the light scalar mesons $f_0(980)$ and $a_0(980)$, dynamically generated from the $S$-wave pseudoscalar meson--pseudoscalar meson interaction within the chiral unitary approach, to the threshold enhancement in the $K_S^0K_S^0$ invariant mass squared distribution, and examine the possible contribution of the intermediate $Σ(1620)$ resonance in the $pK_S^0$ subsystem. We first argue that the $Λ_c^+ \to pK_S^0K_S^0$ channel is a cleaner probe of the $K\bar K$ final-state interaction than the charged channel $Λ_c^+ \to pK^+K^-$, since the $ϕ$ and $Λ^*$ contributions are forbidden and the $Σ(1620)$ and $Σ(1660)$ couple weakly to the $\bar{K}N$ channel. The threshold enhancement in the $K_S^0K_S^0$ invariant mass squared distribution is well described by the $S$-wave $K^0\bar K^0$ final-state interaction alone, with the $f_0(980)$ contribution dominating while that of $a_0(980)$ is small, supporting the interpretation of $f_0(980)$ as a $K\bar K$ hadronic molecular state. Future high-precision measurements by Belle~II and the proposed Super Tau-Charm Facility will help test the roles of the $f_0(980)$ and $a_0(980)$ and of the possible $Σ(1620)$ contribution in this process.

hep-ph↗

arXiv2026

Identifying $Σ(1380)$ and $Σ(1430)$ in the $J/ψ\to Λπ\barΣ$ reaction

We study the $J/ψ\to Λπ\barΣ$ reaction by looking at the $π^+ Λ$ mass distribution at low energies, in search of signals for the low lying $Σ^+$ excited states. Apart from a clear signal of the $Σ(1385) (3/2^+)$ state, we find a smaller peak for the predicted $Σ(1430) (1/2^-)$, which has already been confirmed by the Belle Collaboration. A first analysis, considering only the $πΛ$ interaction, shows that the low energy part of the spectrum is better reproduced including contributions from the $Σ(1430)$ and the predicted $Σ(1380)(1/2^-)$ state that has been claimed before from analyses of different experiments. However, when we consider the $π\barΣ$ interaction the need for the $Σ(1380)$ disappears.

hep-ph↗

arXiv2026

Revisiting the $Λ_c^+ \to nπ^+η$ decay in light of the BESIII measurement

Motivated by the recent BESIII measurement, we revisit the $Λ_c^+\to nπ^+η$ decay within the chiral unitary approach, including internal and external $W$-emission mechanisms and final-state interactions. The $a_0(980)^+$ and $N(1535)^{0,+}$ resonances are dynamically generated by meson--meson and meson--baryon interactions, respectively. With the relative weight of internal to external emission fixed at $1/3$, $2/3$, and $1$, all three scenarios reasonably describe the measured $π^+η$ invariant mass distribution, but yield different fractions for the $a_0(980)$ contribution, and the fraction obtained for $γ=2/3$ and $1$ are numerically below the experimental upper limit. The $a_0(980)$ contribution exhibits a threshold cusp, modified by coherent interference in the total spectrum. Its modest prominence, together with the limited statistical precision and coarse binning, offers a plausible explanation for the absence of a clear experimental signal. We also predict the $ηn$ and $π^+n$ invariant mass distributions. Future high-statistics measurements at BESIII, Belle~II, and STCF would enable a joint analysis to constrain the relative production weight and resonance contributions, providing further insight into the nature of the $a_0(980)$ and $N(1535)$.

hep-ph↗

arXiv2026

Dynamical resonances $Λ(1405)$, $Λ(1670)$, and $f_0(980)$ in the process $Λ_c^+ \to p K^+ K^-$

Motivated by new BESIII measurements of the singly Cabibbo-suppressed process $Λ_c^+ \to p K^+ K^- $, we investigate the $Λ_c^+ \to p K^+ K^-$ reaction by taking into account contributions from the low-lying excited baryons $Λ(1405)$ and $Λ(1670)$, which are dynamically generated via the $S$-wave pseudoscalar meson-octet baryon interaction. In addition, contributions from the light scalar mesons $f_0(980)/a_0(980)$ dynamically generated via the $S$-wave pseudoscalar meson-pseudoscalar meson interaction, as well as the vector meson $ϕ(1020)$, are also considered. The theoretical calculations could reproduce the invariant mass distributions of $K^- p$ and $K^+K^-$ measured by the BESIII Collaboration well. Specifically, a near-threshold enhancement and a cusp structure around 1670~MeV in the $pK^-$ invariant mass spectrum are obtained, which are associated with the $Λ(1405)$ and $Λ(1670)$ resonances, respectively. Furthermore, contributions from the scalar meson $f_0(980)$ and vector meson $ϕ(1020)$ are clearly observed in the $K^+ K^-$ invariant mass distribution. Future high-precision measurements by the BESIII, Belle II, and the proposed Super Tau-Charm Facility experiments will substantially deepen our understanding of the intrinsic properties of the low-lying excited $Λ$ states and the $f_0(980)/a_0(980)$ meson.

hep-ph↗

arXiv2026

Molecular Structure Effects in Low-Lying $P$-wave Bottom-Strange Meson Spectrum

Recently, the LHCb Collaboration reported a new narrow bottom-strange meson, $B_{s0}^*(5700)$ 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 $B_s^0π^0$ 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 $B_{s0}^*$ mass still exceeds the LHCb data by $\sim120$~MeV in a purely compact picture. The inclusion of the coupled-channel dynamics is decisive: the $BK$ threshold, lying close to the scalar mass, generates a sizeable meson--meson (molecular-like) component that pulls the pole down to $\sim5727$~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 $1^+$ $B_{s1}$ partner, for which we predict a mass $\sim5747$--$5755$~MeV, in agreement with the chiral-doubling scenario. The $B_{s1}$ state is expected to be very narrow and decaying mainly through the isospin-violating $B_s^*π^0$ and radiative $B_sγ$, $B_s^*γ$ modes, providing a clear discovery target at LHC Run~3. The $E1$ radiative widths of the $j_\ell=1/2$ states are predicted at the $50\sim 60$~keV, and the strong width of the pure $j_\ell=3/2$ state $B_{s2}^*(5840)$ ($1.5$~MeV) reproduces the measurement. Our results support the interpretation of $B_{s0}^*(5700)$ as a near-threshold scalar with strong molecular dressing and establish the predicted $1^+$ $B_{s1}(5747)$ as the decisive test of the hadronic dynamics in the $B_s$ sector.

hep-ph↗

arXiv2026

GeoBridge++: Fact-Guided Geo-Semantic Bridging for Unified Cross-View Geo-Localization

Cross-view geo-localization infers a location by retrieving geo-tagged reference images matching a query image. However, the traditional satellite-centric paradigm limits robustness when high-resolution or up-to-date satellite imagery is unavailable and underexploits complementary cues across views and modalities. To address these challenges, we propose GeoBridge, a novel model that performs bidirectional matching across views and supports language-to-image retrieval. GeoBridge builds on a novel semantic-anchor mechanism that bridges multi-view features through textual descriptions for robust, flexible localization. We further extend GeoBridge to propose GeoBridge++, a fact-guided geo-semantic bridging framework incorporating real-world geographic knowledge to reduce the ambiguity and instability in appearance-dominated supervision. It integrates structured geographic attributes with visual observations to construct factual descriptions and applies targeted guidance based on modality-specific observable content, thereby enhancing geographic discriminability. GeoBridge++ exploits explicit spatial structures encoded by static maps to build a geo-semantic bridge that adaptively aggregates complementary multi-view information and promotes cross-view consistency. In support of this task, we further construct GeoLoc-MM, a million-scale, multi-view, and multi-scale dataset with aligned drone, satellite, street-view, and static-map imagery at six spatial extents per location, enabling systematic evaluation of arbitrary cross-view retrieval, scale robustness, and cross-view generalization. Extensive experiments show that GeoBridge supports robust cross-view and cross-modal geo-localization, while GeoBridge++ achieves consistent improvements across multiple benchmarks. Code and dataset will be released at https://github.com/MiliLab/GeoBridge.

cs.CV↗

arXiv2026

Role of $K^*_0(700)$ exchange in the $p \bar{p} \to Λ\barΛ$ reaction

Based on the effective Lagrangian approach, we investigate the $p \bar{p} \to Λ\barΛ$ reaction. Within this framework, we provide a dynamical explanation by analyzing its total and differential cross sections, as well as the polarization of the produced $Λ$ hyperon. Incorporating the $t$-channel exchange of the scalar $K^*_0(700)$ and pseudoscalar $K$ mesons, complemented by an $s$-channel contribution from the vector excited state, we can reproduce the current experimental data fairly well in a wide energy region. Compared to the conventional $K$ and $K^*(892)$ mesons exchange, the $K^*_0(700)$ meson exchange plays a more essential role in simultaneously capturing the observed features of the total and differential cross sections. The introduction of the vector $s$-channel resonance improves the description of the spin observables. This work gives a perspective to inspect the role of $K^*_0(700)$ and serves as a test to search for the resonances in the reaction $p \bar{p} \to Λ\barΛ$ at threshold.

hep-ph↗

arXiv2026

Unveiling the elusive $Σ(1380)$ resonance through coupled-channel dynamics in $Λ_c^+\toηπ^+Λ$ reaction

We investigate the $Λ_c^+ \to ηπ^+ Λ$ decay measured by the Belle and BESIII Collaborations, focusing on the possible role of the $Σ(1380)$ state with spin-parity $J^P=1/2^-$. In our theoretical framework, the $Λ(1670)$ and $a_0(980)$ are dynamically generated from meson-baryon and meson-meson final-state interactions, respectively, and the corresponding line shapes of these two states used here are applicable to all relevant hadronic reactions. Furthermore, the contributions from the intermediate $Σ(1385)$ resonance and the possible $Σ(1380)$ state are included explicitly. By comparing the invariant mass and angular distributions obtained with and without the $Σ(1380)$ state, we demonstrate that this state plays an important role in improving the description of the experimental data. We also identify the kinematic regions most sensitive to the possible $Σ(1380)$ contribution. Future high-precision measurements of this process will be instrumental for testing the existence of the $Σ$ state with $J^P=1/2^-$.

hep-ph↗

arXiv2026

Finding a clean process $B^- \to K^- D^0 K^0$ to probe absolutely exotic four-quark states

Motivated by the observations of $T_{c\bar{s}0}(2900)^0$ and $T_{c\bar{s}0}(2900)^{++}$, we propose to search for $\tcsbar^0$ in the cleaner process $B^- \to K^- D^0 K^0$. In the $D^*K^*$ molecular picture, our estimates suggest that $T_{c\bar{s}0}(2900)^0$ should contribute significantly to the $D^0 K^0$ invariant mass distribution in $B^- \to K^- D^0 K^0$, as reported by the Belle II Collaboration. The corresponding fit fraction is estimated to be $(9.72\pm 3.92)\%$ or $(7.09\pm 5.88)\%$ in different fitting schemes. Further precise measurements of this process at Belle II and LHCb could be helpful for clarifying the nature of $T_{c\bar{s}0}(2900)$.

hep-ph↗

arXiv2026

Search for the low-lying excited baryon $Σ^*(1/2^-)$ through process $Λ^+_c \to ΛK^0 π^+$

Motivated by recent BESIII measurements of the singly Cabibbo-suppressed processes $Λ^+_c \to ΛK^+ π^0$ and $Λ^+_c \to ΛK_S^0 π^+$, we investigate the process $Λ^+_c \to ΛK^0 π^+$ by taking into account the contribution from the low-lying excited baryon $Σ^*(1/2^-)$, dynamically generated via the $S$-wave pseudoscalar meson-octet baryon interaction, as well as from the intermediate resonances $K^*(892)$ and $N(1535)$. Our model successfully reproduces the BESIII $π^+K^0$ invariant mass distribution, and predicts a distinct cusp structure around 1.43~GeV in the $π^+Λ$ invariant mass distribution, which is associated with the predicted $Σ^*(1/2^-)$. Future high-precise measurements of this process at BESIII, Belle~II, and the proposed Super Tau-Charm Facility experiments will be crucial for testing the existence of $Σ^*(1/2^-)$ and advancing our understanding of the light baryon spectrum.

hep-ph↗

arXiv2026

Probing the isospin structure and low-lying resonances in $Λ_c^+ \to n\bar{K}^0 π^+$ decays

The Cabibbo-favored decay $Λ_c^+ \to n \bar{K}^0π^+$ offers a unique window to explore unresolved puzzles in the low-energy baryon spectroscopy and the isospin dynamics of the $\bar{K}N$ system. Recent experimental results present a, for now, contradiction: LHCb and Belle analyses of $Λ_c^+ \to p K^-π^+$ suggest the $pK^-$ ($I=0$) component dominates, while the Beijing Spectrometer III (BESIII) hints at significant contributions from both isospin $0$ and $1$ in the $n\bar{K}^0$ system of $Λ_c^+ \to n K_S^0 π^+$. Furthermore, the measured branching fraction of $Λ_c^+ \to n K_S^0 π^+$ exceeds SU(3) symmetry predictions by a factor of 3-4, signaling strong contributions from low-lying resonances. In this work, we provide a theoretical analysis of $Λ_c^+ \to n \bar{K}^0π^+$ within the coupled-channel chiral unitary approach, where the $N(1535)$ and $Λ(1670)$ can be dynamically generated. Our calculations show a narrow peak from $N(1535)$ in the $π^+ n$ invariant mass spectrum and a distinct dip from $Λ(1670)$ in the $\bar{K}^0 n$ spectrum. The dip structure is qualitatively consistent with the $Λ(1670)$ manifestation in $\bar{K}N \to \bar{K}N$ scattering, supporting its molecular interpretation. This study not only connects the experimental observations but also highlights $Λ_c^+ \to n \bar{K}^0π^+$ as a crucial process to disentangle the nature of $N(1535)$ and $Λ(1670)$. Future precise measurements of this decay channel by the BESIII, Belle II, LHCb, and the proposed Super Tau-Charm Factory are strongly encouraged.

hep-ph↗

arXiv2026

Token-Level Policy Optimization: Linking Group-Level Rewards to Token-Level Aggregation via Sequence-Level Likelihood

Group Relative Policy Optimization (GRPO) has significantly advanced the reasoning ability of large language models (LLMs), particularly in their mathemat ical reasoning performance. However, GRPO and related entropy regularization methods still struggle with token-level sparse-rewards, which is an inherent chal lenge in chain-of-thought (CoT) reasoning. These approaches often rely on undifferen tiated token-level entropy regularization, which easily leads to entropy collapse or model degradation under sparse token rewards. In this work, we propose TEPO, a novel token-level framework that (1) leverages sequence-level likelihood to link group-level rewards with individual tokens via token-level aggregation, and (2) introduces a token-level KL-Divergence mask constraint that targets tokens with positive advantages and decreasing entropy to mitigate abrupt policy updates. Experiments demonstrate that TEPO not only achieves state-of-the-art performance on mathematical reasoning benchmarks but also markedly enhances training stability, reducing convergence time by 50% compared with GRPO/DAPO.

cs.CL↗

arXiv2026

The dynamically generated $N(1535)$ state in the $Λ_c^+ \to p\bar{K}^0 π^0$ decay

We present a theoretical analysis of the process $Λ_c^+ \to p\bar{K}^0 π^0$ within the chiral unitary approach, with particular emphasis on the dynamically generated $N(1535)$ resonance. In addition to $N(1535)$, our model incorporates contributions from other intermediate resonances including $N(1650)$, $K^*(892)$, $K_0^*(1430)$, $N(1440)$, and $Σ(1750)$. The calculated invariant mass distributions and Dalitz plot are in good agreement with the recent Belle measurements. Our analysis highlights the crucial role of $N(1535)$ state in this decay channel and supports its interpretation as a dynamically generated state arising from coupled-channel meson-baryon interactions.

hep-ph↗

arXiv2026

Role of $Σ(1660)$ in the $K^- p \toπ^0π^0Σ^0$ reaction

The processes of $K^-p \to π^0 π^0 Σ^0$ and $K^- p \to π^0 Λ(1405)$ are studied within the effective Lagrangian approach. In addition to the ``background" contribution from the $u$-channel nucleon pole term, contribution from the $Σ(1660)$ resonance with spin-parity $J^P=1/2^+$ is also considered. For the $K^-p \to π^0 π^0 Σ^0$ reaction, we perform a calculation for the total and differential cross sections by considering the contribution from the $Σ(1660)$ intermediate resonance decaying into $π^0 Λ(1405)$ with $Λ(1405)$ decaying into $π^0 Σ^0$. With our model parameters, the available experimental data on both the $K^-p \to π^0 π^0 Σ^0$ and $K^- p \to π^0 Λ(1405)$ reactions can be fairly well reproduced. It is shown that we really need the contribution from the $Σ(1660)$ resonance, and that these experimental measurements could be used to determine some properties of the $Σ(1660)$ resonance.

hep-ph↗

arXiv2025

Token-Level Policy Optimization: Linking Group-Level Rewards to Token-Level Aggregation via Markov Likelihood

Group Relative Policy Optimization (GRPO) has significantly advanced the reasoning ability of large language models (LLMs), particularly by boosting their mathematical performance. However, GRPO and related entropy-regularization methods still face challenges rooted in the sparse token rewards inherent to chain-of-thought (CoT). Current approaches often rely on undifferentiated token-level entropy adjustments, which frequently lead to entropy collapse or model collapse. In this work, we propose TEPO, a novel token-level framework that incorporates Markov Likelihood (sequence likelihood) links group-level rewards with tokens via token-level aggregation. Experiments show that TEPO consistently outperforms existing baselines across key metrics (including @k and accuracy). It not only sets a new state of the art on mathematical reasoning tasks but also significantly enhances training stability.

cs.CL↗

arXiv2025

Roles of $a_0(980)$ and $a_0(1710)$ in Cabibbo-suppressed process $D^+\to π^0π^+η$

Motivated by the BESIII amplitude analysis of the single Cabibbo-suppressed process $D^+\to π^0π^+η$, we investigate this reaction by taking into account the contributions from the $a_0(980)$, $ρ$, and $a_0(1710)$, where the scalar meson $a_0(980)$ could be dynamically generated from the $S$-wave pseudoscalar meson-pseudoscalar meson interaction within the chiral unitary approach. Our theoretical predictions for the $π^0η$, $π^+η$, and $π^+π^0$ invariant mass distributions are in agreement with the BESIII measurements, especially the clear peaks around 1~GeV in the $π^0η$ and $π^+η$ invariant mass distributions could be associated with the dynamically generated state $a_0(980)$. Furthermore, we demonstrate that the intermediate $a_0(1710)$ is also necessary to describe the enhancement structure around $1.6\sim 1.7$~GeV in the $π^{0/+}η$ invariant mass distribution. More precise experimental measurements of this process could provide deeper insights into the nature of the scalar mesons $a_0(980)$ and $a_0(1710)$.

hep-ph↗

arXiv2025

The $B^-\to J/ψη^\prime K^-$ reaction and the $Y(4710)$ and $K_0^*(1430)$ contributions

Motivated by the recent LHCb Collaboration analysis, we have investigated the process $B^-\to J/ψη^\prime K^-$ by considering the contributions from the resonances $Y(4710)$ and $K_0^*(1430)$. Our results are in good agreement with the measured invariant mass distributions and the Dalitz plot of LHCb, which supports the existence of the $K_0^*(1430)$ and the $Y(4710)$ in the process $B^-\to J/ψη^\prime K^-$. Since the decay mode of $Y(4710)\to J/ψη'$ is Okubo-Zweig-Iizuka (OZI) suppressed for the charmonium state, the measurements of the $\mathcal{B}(Y(4710)\to J/ψη')$ through the process $B^-\to J/ψη' K^-$ or other processes is helpful to understanding the nature of the $Y(4710)$. Thus, we advocate that Belle~II and LHCb Collaborations could perform the more precise analysis to confirm the evidence of the $Y(4710)$ state, which could be helpful to reduce the experimental uncertainties of its mass and width, and to explore its nature.

hep-ph↗

arXiv2025

Hadronic decay $D^+\toπ^+ηη$ and the $a_0(980)$ and $f_0(1370)$ contributions

Motivated by the resent BESIII Collaboration measurements of the process $D^+\toπ^+ηη$, we investigate this process by considering the contribution from the resonance $a_0(980)$, which is generated by $S$-wave pseudoscalar meson-pseudoscalar meson interaction, and the contribution from the intermediate scalar meson $f_0(1370)$. Our results could give a good description of the $π^+η$ and $ηη$ invariant mass distributions, which implies that the contribution from the intermediate $f_0(1370)$, neglected in BESIII analysis, could play a role in this process. Furthermore, the predicted Dalitz plots are also consistent with the BESIII measurements. The more precise measurements about this process in future could shed light on the mechanism of this process and the properties of $f_0(1370)$ and $a_0(980)$.

hep-ph↗