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

China

Xing-Yi Ji

Si-Wei Liu

Wen-Tao Lyu

De-Min Li

En Wang

Ju-Jun Xie

Role of Σ(1660) in the $\textit{K}$ $^{−}$ $\textit{p}$ → $\textit{π}$ $^{0}$ $\textit{π}$ $^{0}$Σ$^{0}$ reaction * Supported by the National Key R&D Program of China (2023YFA1606703, 2024YFE0105200), the National Natural Science Foundation of China (12435007, 12475086, 12192263, 12361141819, 1252200936), the Natural Science Foundation of Henan (232300421140, 252300423951) and the Zhengzhou University Young Student Basic Research Projects (PhD students) (ZDBJ202522)

We have performed an updated analysis of the angular distribution of the $ \psi(3686) \to p\bar{p} $ decay by considering transverse beam polarization to investigate potential sources of forward-backward asymmetry and azimuthal modulation beyond the simple $ 1+\alpha\cos^2\theta $ form. We focus on the interference between the $ \psi(3686) $ resonance and two-photon exchange continuum process, as well as on the background from initial-state–final-state radiation (ISR–FSR) interference. A maximum-likelihood fit to the $ \cos\theta $ distribution of $ \psi(3686)\to p\bar{p} $ yields $ \alpha = 1.00 \pm 0.03 $ , which is consistent with previous results. Our model predicts a significant $ \sin(2\phi) $ modulation in the azimuthal angle, indicating the influence of transverse beam polarization. Based on these findings, two-dimensional angular analyses can be conducted in the future to fully disentangle the polarization and interference dynamics in charmonium decays to baryon pairs.

Zhi Gao

Rong-Gang Ping

Minggang Zhao

Update analysis of $ {\psi(3686)\to p\bar{p}}$ * The work is partly supported by the National Natural Science Foundation of China(NSFC) (12575112)

This study investigates the ultraviolet realization of semileptonic four-fermion operator $ O_{ledq}^{\alpha \beta 11} $ that incorporates Majorana dark matter (DM) in both lepton-flavor-conserving (LFC) and lepton-flavor-violating (LFV) scenarios at the one-loop level via box diagram, thereby effectively alleviating the lower bounds on the new physics scale. In addition, we investigate the interplay between model-independent constraints on the Wilson coefficients and DM direct detection, relic density, and collider searches in the context of fermion portal DM model with two mediators. We found that both the projected future constraint on the LFC Wilson coefficient $ C_{ledq}^{2211}/\Lambda^2 \lt $ $ (12.3\; \text{TeV})^{-2} $ from the measurements of neutrino non-standard interaction in the next-generation neutrino oscillation experiments, and the LFV constraint $ C_{ledq}^{1211}/\Lambda^2 \lt \left(2.2\times 10^3\; \text{TeV} \right)^{-2} $ from ongoing charged-lepton-flavor-violation searches, provide a complementary exploration of the parameter space encompassing the DM and scalar masses. With a colored mediator mass of approximately $ 2\; \text{TeV} $ , the sensitivity of the indirect constraints on the four-fermion operator can surpass those of collider searches and DM direct detection, in scenarios where the masses of the DM and scalar are close. By ensuring the correct DM relic density, however, we find that the collider searches and DM direct detection are more sensitive to the electroweak-scale DM and scalar than indirect constraints.

Yuxuan He

Gang Li

Jia Liu

Xiao-Ping Wang

Xiang Zhao

Lepton flavor of four-fermion operator and fermion portal dark matter * Gang Li and Xiang Zhao are supported by the National Natural Science Foundation of China (12347105, 12505127), the Guangdong Basic and Applied Basic Research Foundation (2024A1515012668). The work of Jia Liu is supported by the National Science Foundation of China (12235001, 12475103) and State Key Laboratory of Nuclear Physics and Technology (NPT2025ZX11). The work of Xiao-Ping Wang is supported by National Science Foundation of China (12375095) and the Fundamental Research Funds for the Central Universities

We have performed a next-to-leading-order (NLO) QCD sum rules analysis of the $1^{-+}$ light tetraquark states. By investigating various compact and molecular tetraquark currents, we extracted the mass spectra of the corresponding states, all of which lie above $1.7\,\text{GeV}$ . We have identified multiple $1^{-+}$ states around $2.0\,\text{GeV}$ matching well with $\pi_{1}(2015)$ , confirming that $\pi_{1}(2015)$ is an excellent tetraquark candidate. By contrast, our calculations exclude the possibility that the $\pi_{1}(1400)$ is a tetraquark or hybrid–tetraquark mixture. This result suggests that it may not exist, which is consistent with recent experimental results.

Wei-Yang Lai

Hong-Ying Jin

NLO QCD sum rules analysis of 1$^{− +}$ tetraquark states

We investigate the oscillation of the Kasner exponent $$p_t$$ near the critical point of hairy black holes dual to holographic superfluid and reveal a clear inverse periodicity $$f(T_c/(T_c-T))$$ in a large region below the critical temperature. We first introduce the fourth-power term with a coefficient $$\lambda $$ to adjust the oscillatory behavior of the Kasner exponent $$p_t$$ near the critical point. Importantly, we show that the nonlinear coefficient $$\lambda $$ provides accurate control of this periodicity: a positive $$\lambda $$ stretches the region, while a negative $$\lambda $$ compresses it. By contrast, the influence of another coefficient $$\tau $$ is more concentrated in regions away from the critical point. This work provides a new perspective for understanding the complex dynamical structure inside black holes and extends the active control from the fourth- and sixth-power terms into the black hole interior region.

Zi-Qiang Zhao

Zhang-Yu Nie

Xing-Kun Zhang

Yu-Sen An

Jing-Fei Zhang

Xin Zhang

Interior structure of black holes with nonlinear terms

We investigate the cosmological implications of an extended gravitational framework based on biconnection gravity, constructed from the Schr $$\ddot{\textrm{o}}$$ dinger connection and its dual. In this approach, the difference between the two connections defines the mutual curvature, which encodes the non-Riemannian geometric degrees of freedom, while their symmetric combination reduces to the Levi-Civita connection and hence reproduces general relativity at the background level. Within this setting, we derive the generalized Friedmann equations for a spatially flat Friedmann–Lemaître–Robertson–Walker Universe. The resulting equations contain additional geometric contributions that may naturally encode an effective dark energy sector induced by the biconnection degrees of freedom. We explore this extra dark energy by adopting five commonly used parametrizations, namely B $$\Lambda $$ CDM, $$\omega $$ CDM, Chevallier–Polarski–Linder, Barboza–Alcaniz, and a logarithmic equations of state. These considerations are confronted with recent observational data, including DESI DR2, Pantheon $$^+$$ , and CC observations. Our analysis shows that the four parameterizations enter the acceleration phase at almost the same redshifts and share the same current value of the Hubble rate. Furthermore, the statistical comparison based on the Akaike, Bayesian, and Deviance Information Criterion shows that Barboza–Alcaniz, and logarithmic parameterizations have strong evidence and are competitive with $$\Lambda $$ CDM. To classify this biconnection gravity in the plethora theoretical models describing the current cosmic acceleration, we examine its implications through cosmographic tools, including the deceleration, jerk, and snap parameters, as well as through the Statefinder analysis and $\textit{Om}$($\textit{z}$) diagnostic. These diagnostics indicate that the geometric sector generates a dynamical dark energy component that remains observationally close to $$\Lambda $$ CDM at the background level. Indeed, the effective evolution of the biconnection gravity begins initially from a quintessence-like regime and subsequently evolves toward a phantom-like regime. All parameterizations under consideration face this transition in the recent past, except for the $$\omega $$ CDM model, which enters the phantom-like regime in the future.

Morocco

D. Mhamdi

A. Bouali

T. Ouali

Romania

T. Harko

Cosmological test of a length-preserving biconnection gravity

We study the influence of the instantaneous appearance of a conformal Killing vector (CKV) in self-gravitating fluid spheres during their evolution. For doing that we introduce a tensor variable whose time dependence allows the existence of a CKV for a given value of the time-like coordinate. We consider adiabatic and dissipative fluids. The analysis of different relevant physical variables in this process provides a smoking gun signature from the emergence of CKV at some point of the evolution. Prospective applications of these results, as well as open questions and pending issues related to this problem, are discussed.

Spain

L. Herrera

Venezuela

A. Prisco

J. Ospino

The imprints of the instantaneous appearance of a conformal Killing vector field on the evolution of self-gravitating fluid spheres

We investigate gluonic hidden-charm tetraquark states composed of two valence quarks, two valence antiquarks and an explicit valence gluon. In the color configuration $$[\bar{3}_c]_{c q}\otimes [8_c]_{G}\otimes [3_c]_{\bar{c}\bar{q}}$$ , a complete set of eight interpolating currents is constructed for states with quantum numbers $$^{PC}=0^{++}$$ , $$0^{-+},$$ $$0^{-}{-}$$ , and $$0^{+-}$$ . The corresponding mass spectra are systematically analysed within the QCD sum rule framework, including nonperturbative condensate contributions up to dimension eight. Our numerical analysis indicates the possible existence of six gluonic hidden-charm tetraquark states exhibiting stable behaviour in the adopted Borel windows. By replacing the charm quark with the bottom quark, masses for the corresponding hidden-bottom partners are also estimated. Possible production mechanisms and dominant decay channels are discussed, providing phenomenological guidance for experimental searches. These predicted states may be accessible at current and forthcoming facilities, including Belle II, PANDA, SuperB and LHCb, and thus offer an opportunity to probe explicit gluonic degrees of freedom in multiquark systems and deepen our understanding of nonperturbative QCD.

Bing-Dong Wan

Ming-Yang Yuan

Jun-Hao Zhang

Yan Zhang

Spectrum of $$J^{PC} = 0^{\pm \pm }$$ gluonic hidden-charm tetraquark states

Parton densities are obtained from a solution of the extended DGLAP-type evolution equation that includes both QCD and electroweak contributions. The equations are solved using the Parton-Branching (PB) approach, and the evolution is performed at next-to-leading order for QCD partons and leading order for electroweak bosons. The initial QCD parton distributions are fitted to HERA deep inelastic scattering data, while photon and weak-boson densities are generated perturbatively and validated against $$d\sigma /dQ^2$$ . The resulting collinear and transverse-momentum dependent (TMD) densities are provided in LHApdf and TMDlib formats for direct phenomenological use.

Germany

K. Moral Figueroa

E. Gallo

Belgium

H. Jung

S. Taheri Monfared

Determination of parton densities for QCD partons and electroweak bosons

We investigate the elastic scattering of sufficiently low-energy neutrinos by the ultra-relativistic electrons passing through the single crystal possessing a sufficiently strong internal electrostatic field. When the energy of the accelerated electron in the initial state is $$500 GeV$$ , the influence of the effective magnetic field generated by the relative motions of the crystalline electrostatic field and accelerated electrons passing through the single crystal on the elastic scattering of relic neutrinos by the accelerated electrons becomes significant if the generated magnetic field strength changes in the range $$4.50\times {10}^{8}G\lesssim B_{ef} \lesssim 1.42\times {10}^{9}G$$ . After the elastic scattering of relic neutrinos by the ultra-relativistic electrons possessing energy $$500 GeV$$ , the average energy of the scattered relic neutrinos is amplified up to $$\sim {10}^{2} GeV$$ . The numerical estimations show that the flux of the boosted relic neutrinos originated from the accelerated electrons passing through the tungsten single crystal is on the detectable level at the IceCube detector. If the boosted relic neutrinos originated from the elastic scattering of relic neutrinos by the ultra-relativistic electrons passing through the tungsten located in the way of the accelerated electrons are detected at the IceCube or any other related neutrino detector, it would constitute direct evidence for the existence of the cosmic neutrino background. The comparison of the boosted solar thermal neutrino flux and the boosted relic neutrino flux arriving at the detector shows that the former is much smaller than the latter and does not prevent a detection of the boosted relic neutrinos.