In this work, we investigate the resonance structures in the $ \Sigma(1/2^-) $ system from both three-quark and five-quark perspectives within the framework of the chiral quark model. An accurate few-body computational approach, the Gaussian expansion method, is employed to construct the orbital wave functions of multiquark states. To reduce the model dependence on parameters, we fit two sets of parameters to check the stability of the results. The calculations show that our results remain stable despite changes in the parameters. In the three-quark calculations, two $ \Sigma(1/2^-) $ states are obtained with energies around 1.8 GeV, which are good candidates for the experimentally observed $ \Sigma(1750) $ and $ \Sigma(1900) $ . In the five-quark configuration, several stable resonance states are identified, including $ \Sigma \pi $ , $ N \bar{K} $ , and $ N \bar{K}^{*} $ . These resonance states survive the channel-coupling calculations under the complex-scaling framework and manifest as stable structures. Our results support the existence of a two-pole structure for the $ \Sigma(1/2^-) $ system, predominantly composed of $ \Sigma \pi $ and $ N \bar{K} $ configurations, analogous to the well-known $ \Lambda(1380) $ - $ \Lambda(1405) $ ( $ \Sigma \pi $ - $ N \bar{K} $ ) system. On the other hand, although the energy of the $ N \bar{K}^{*} $ configuration is close to that of $ \Sigma(1750) $ and $ \Sigma(1900) $ , the obtained width is not consistent with the experimental values. This suggests that the $ N \bar{K}^{*} $ state needs to mix with three-quark components to better explain the experimental $ \Sigma(1750) $ and $ \Sigma(1900) $ states. According to our decay width calculations, the predicted two resonance states are primarily composed of $ \Sigma \pi $ and $ N \bar{K} $ , with their main decay channel being $ \Lambda \pi $ . Therefore, we encourage experimental groups to search for the predicted two-pole structure of the $ \Sigma(1/2^-) $ system in the invariant mass spectrum of $ \Lambda \pi $ .

China

Yu Yao

Xuejie Liu

Xiaoyun Chen

Yuheng Wu

Jialun Ping

Yue Tan

Qi Huang

Investigation of resonances in the Σ(1/2$^{–}$) system based on the chiral quark model * Supported partly by the National Science Foundation of China (12205249, 12305087). Yue Tan is supported by the Funding for School-Level Research Projects of Yancheng Institute of Technology (xjr2022039) and the Qinglan Project Fund of Jiangsu Province. Qi Huang is supported by the Start-up Funds of Nanjing Normal University (184080H201B20)

A recent independent dark photon (DP) focused reanalysis of existing data from the TASEH axion haloscope experiment reported a tentative DP dark matter signal with local significance <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>∼</mo><mn>4.7</mn><mi>σ</mi></math> at a frequency <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>f</mi><mo>≈</mo><mn>4.71</mn><mtext> </mtext><mtext> </mtext><mrow><mi>GHz</mi></mrow></mrow></math>, corresponding to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>X</mi></mrow></msub><mo>≈</mo><mn>19.5</mn><mtext> </mtext><mtext> </mtext><mi mathvariant="normal">μ</mi><mi>eV</mi></mrow></math> and kinetic mixing <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ϵ</mi><mo>∼</mo><mn>6.5</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>15</mn></mrow></msup></mrow></math>. Motivated by this report, we performed a dedicated, narrowband follow-up experiment to confirm or refute the signal with a cryogenic microwave cavity operated without a magnetic field, leveraging the ORGAN-Q dilution refrigeration and receiver chain. Scanning a window centered on the reported frequency over a live time of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>int</mi></msub><mo>∼</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>days</mi></math>, we find no excess consistent with a dark photon signal as reported, and set a 95% CL of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ϵ</mi><mo>≤</mo><mn>5.04</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>15</mn></mrow></msup></mrow></math> in a narrow mass range around <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>∼</mo><mn>19.5</mn><mtext> </mtext><mtext> </mtext><mi mathvariant="normal">μ</mi><mi>eV</mi></math>, excluding a signal of the strength and frequency reported to 99.92% confidence. We discuss the experiment and present the exclusion limits.

Australia

Aaron P. Quiskamp

Graeme R. Flower

Maxim Goryachev

Michael E. Tobar

Ben T. McAllister

Follow-up search for a tentative dark photon signal near <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>19.5</mn><mtext> </mtext><mtext> </mtext><mi mathvariant="normal">μ</mi><mi>eV</mi></mrow></math> using the ORGAN-Q infrastructure

We present limits on spin-independent inelastic weakly interacting massive particle (WIMP)-nucleus scattering using the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>737.1</mn><mtext> </mtext><mtext> </mtext><mi>kg</mi><mo>·</mo><mi>day</mi></mrow></math> dataset from the CDEX-1B experiment. Expected nuclear recoil spectra for various inelastic WIMP masses <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>χ</mi></msub></math> and mass splittings <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>δ</mi></math> are calculated under the standard halo model. An accurate background model of CDEX-1B is constructed by simulating all major background sources. The model parameters are then determined through maximum likelihood estimation and Markov chain Monte Carlo fitting. The resulting 90% confidence level upper limits on the WIMP-nucleon cross section <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>σ</mi><mi mathvariant="normal">n</mi></msub></math> exclude certain DAMA/LIBRA allowed regions: the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>χ</mi><mn>2</mn></msup><mo>&lt;</mo><mn>4</mn></math> regions for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>δ</mi><mo>&lt;</mo><mn>30</mn><mtext> </mtext><mtext> </mtext><mi>keV</mi></math> at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>χ</mi></msub><mo>=</mo><mn>250</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> and the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>χ</mi><mn>2</mn></msup><mo>&lt;</mo><mn>9</mn></math> region for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>δ</mi><mo>&lt;</mo><mn>50</mn><mtext> </mtext><mtext> </mtext><mi>keV</mi></math> at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>χ</mi></msub><mo>=</mo><mn>500</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>. The method is applicable to other inelastic dark matter scenarios, and the upcoming CDEX-50 experiment is expected to improve sensitivity by four orders of magnitude.

Y.F. Liang

L.T. Yang

Q. Yue

K.J. Kang

Y.J. Li

H.P. An

Taiwan

Greeshma C.

J.P. Chang

H. Chen

Y.H. Chen

J.P. Cheng

J.Y. Cui

W.H. Dai

Z. Deng

Y.X. Dong

C.H. Fang

H. Gong

Q.J. Guo

T. Guo

X.Y. Guo

L. He

J.R. He

H.X. Huang

T.C. Huang

S. Karmakar

Y.S. Lan

H.B. Li

H.Y. Li

J.M. Li

J. Li

M.C. Li

Q.Y. Li

R.M.J. Li

X.Q. Li

Y.L. Li

B. Liao

F.K. Lin

S.T. Lin

J.X. Liu

R.Z. Liu

S.K. Liu

Y.D. Liu

Y. Liu

Y.Y. Liu

H. Ma

Y.C. Mao

A. Mureed

H. Pan

N.C. Qi

J. Ren

X.C. Ruan

M.B. Shen

H.Y. Shi

M.K. Singh

T.X. Sun

W.L. Sun

C.J. Tang

Y. Tian

H.F. Wan

G.F. Wang

J.Z. Wang

L. Wang

Q. Wang

Y.F. Wang

Y.X. Wang

H.T. Wong

Y.C. Wu

H.Y. Xing

K.Z. Xiong

R. Xu

Y. Xu

T. Xue

Y.L. Yan

N. Yi

C.X. Yu

H.J. Yu

X. Yu

M. Zeng

Z. Zeng

F.S. Zhang

P. Zhang

Z.Y. Zhang

M.G. Zhao

J.F. Zhou

Z.Y. Zhou

J.J. Zhu

Constraints on inelastic dark matter from the CDEX-1B experiment

We numerically study the formation of the gauge-mediation type <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math> balls in the logarithmic square potential on three-dimensional lattices. We obtain the broad charge distribution of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math> ball of this type for the first time, to the best of our knowledge. The charge of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math> ball at the peak of the distribution is smaller than what we estimated as the average of the largest tens of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math> balls in the logarithmic potential for the same initial amplitude of the field at the onset of its oscillation. We also discuss some impacts of the broad distribution on cosmology and astrophysics. In the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> ball (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math> being the baryon number) case, the broad distribution would lead to the coexistence of both stable and unstable <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> balls. We find that stable <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> balls can account for the dark matter of the Universe without affecting successful big bang nucleosynthesis by the decay of the unstable <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> balls, but the baryon number of the Universe cannot be explained by them. On the other hand, the large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>L</mi></math> balls (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math> being the lepton number) would be the dark matter as well while avoiding the constraints on the x- and/or <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi></math>-rays from the decay of the smaller <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>L</mi></math> balls.

Japan

Shinta Kasuya

Masahiro Kawasaki

Charge distribution of the gauge-mediation type <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math> ball

Charged lepton flavor-violating (cLFV) processes, which are definite proof of new physics beyond the Standard Model, have remained experimentally elusive to date. Effective field theory (EFT) has been very useful in providing information about such new physics through the higher-dimensional operators. These operators respect SM gauge invariance, and they are suppressed by appropriate powers of the energy scale <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Λ</mi></math>. In regard to lepton flavour violating (LFV) processes, the Standard Model effective field theory (SMEFT) is shown to be a useful tool for estimating any new physics effect at the scale <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Λ</mi></math>. It is worth noting that a large class of cLFV processes involves both quarks and leptons. Thus, low-energy observables play a significant role in providing bounds on lepton-flavor-violating 2-quark-2-lepton (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mi>q</mi><mn>2</mn><mo>ℓ</mo></math>) operators. In this work, we explore several low-energy cLFV processes that can be addressed within the SMEFT framework, relating them to the specific operators of relevance. Keeping in mind the correlation that exists among the SMEFT operators, we want to extract the strongest constraints on these <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mi>q</mi><mn>2</mn><mo>ℓ</mo></math> operators.

India

Utpal Chattopadhyay

Debottam Das

Rahul Puri

Joydeep Roy

Constraining lepton flavor violating SMEFT <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mi>q</mi><mn>2</mn><mo>ℓ</mo></math> operators from low-energy charged lepton flavor-violating processes

We study a multicomponent <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><msup><mi>P</mi><mi>N</mi></msup></math> model’s scalar electrodynamics. The model contains <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-balls and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-shells, which are nontopological compact solitons with time dependency <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mrow><mi>i</mi><mi>ω</mi><mi>t</mi></mrow></msup></math>. Two coupled <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><msup><mi>P</mi><mi>N</mi></msup></math> models can decouple locally if one of their <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><msup><mi>P</mi><mi>N</mi></msup></math> fields takes the vacuum value. Because of the compacton nature of solutions, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-shells can shelter another compact <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-ball or <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-shell within their hollow region. Even if compactons do not overlap, they can interact through the electromagnetic field. We investigate how the size of multicompacton formations is affected by electric charge, with a focus on structures with nonzero or zero total net charge.

Brazil

P. Klimas

L.C. Kubaski

N. Sawado

S. Yanai

Gauged compact <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>Q</mi></mrow></math>-balls and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-shells in a multicomponent <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><msup><mi>P</mi><mi>N</mi></msup></math> model

<list id='lst0002'><list-item id='lstitem0001'><label>&#8226;</label><para id='p0001'>The non-coincident branch introduces a genuine dynamical scalar degree of freedom from the connection, allowing a scalar-tensor representation of the theory and enabling nontrivial vacuum solutions.</para></list-item><list-item id='lstitem0002'><label>&#8226;</label><para id='p0002'>We obtain cosmologically significant analytic solutions including de Sitter, scaling regimes, &#923;CDM mimicking dynamics, standard and generalized Chaplygin gas, and CPL parameterizations, all reconstructed within the <italic>f</italic>(<italic>Q</italic>) framework.</para></list-item><list-item id='lstitem0003'><label>&#8226;</label><para id='p0003'>These analytic solutions show that the non-coincident formulation admits a richer solution space than both the coincident gauge and <italic>f</italic>(<italic>T</italic>) teleparallel limits, capturing both early and late accelerated phases without matter sources.</para></list-item><list-item id='lstitem0004'><label>&#8226;</label><para id='p0004'>The results demonstrate that non-coincident <italic>f</italic>(<italic>Q</italic>) gravity can unify inflation and late acceleration geometrically, offering a promising alternative to dark-energy driven &#923;CDM.</para></list-item></list>

Malaysia

Avik De

South Africa

Chile

Andronikos Paliathanasis

Exact cosmological solutions in vacuum non-coincidence <italic>f</italic>( <italic>Q</italic>)-theory

We show that, in the thin-wall regime, $\textit{Q}$-ball-anti-$\textit{Q}$-ball collisions reveal chaotic behaviour. This is explained by the resonant energy transfer mechanism triggered by the internal modes hosted by the $\textit{Q}$-balls and by the existence of $\textit{ephemeral}$ states, that is unstable, sometimes even short-lived, field configurations that appear as intermediate states. The most important examples of such states are the $\textit{bubble}$ of the false broken vacuum, which as intermediate states govern the $\textit{QQ}$ annihilation, and the $\textit{charged oscillons}$.

Spain

D. Canillas Martínez

United Kingdom

P. Dorey

Poland

T. Romańczukiewicz

Paul Saffin

K. Sławińska

A. Wereszczyński

Oscillons and bubbles in $\textit{Q}$-ball dynamics

We study the holographic dual of the extended thermodynamics of spherically symmetric, charged Gauss–Bonnet AdS black holes in the context of the AdS/CFT correspondence. Compared to Einstein’s theory of gravity, Gauss–Bonnet gravity introduces higher-order curvature terms. The coupling constants of these higher-order curvature terms $$\alpha $$ can serve as new thermodynamic quantities, which will also be dual to thermodynamic quantities on the boundary CFT, a feature not present in the CFT dual to Einstein’s gravity previously. Based on the holographic dictionary, we studied the critical behavior and phase transition of the CFT description of the charged Gauss–Bonnet black holes in $$d=4$$ and $$d=5$$ in the ensemble at fixed $$(C, \mathcal {V}, \tilde{Q}, \tilde{\mathcal {A}})$$ . The interesting behaviour of free energy stems from the fact that the constraints we introduced to handle the gravitational constant on CFT and the AdS radius differ from conventional approaches. Using the criticality equation, we numerically found the critical points of the zeroth-order and first-order phase transition for $$\tilde{\mathcal {A}}$$ . The relationships between conjugate thermodynamic pairs (equation of state) were also examined. In the case of the $$p-\mathcal {V}$$ , $$\tilde{T}-\tilde{S}$$ and $$\tilde{\varPhi }-\tilde{Q}$$ conjugate pairs, characteristics that are analogous to the first-order phase transition of van der Waals fluids were found.

Limin Zeng

Holographic CFT phase transitions and criticality for charged Gauss–Bonnet AdS black holes in the ensemble at fixed $$(C, \mathcal {V}, \tilde{Q}, \tilde{\mathcal {A}})$$

We develop a unified dynamical systems framework for spatially flat FLRW cosmology in $\textit{f}$($\textit{Q}$) gravity, covering all three connection branches using a single set of Hubble-normalised variables without fixing the function $\textit{f}$($\textit{Q}$) a priori. This model-independent and connection-agnostic approach enables direct comparison across connection choices and uncovers structural features of the cosmological dynamics not visible in connection-specific formulations. While the existing works narrowly focus only on fixed point analysis, in our work we put special efforts to identify the invariant submanifolds, model-independent trajectories and physically viable regions of phase space across connections. For a broad class of viable $\textit{f}$($\textit{Q}$) models, we establish the generic existence of de Sitter attractors and matter-dominated fixed points in the two branches of connection, offering a robust route to late-time acceleration without fine-tuning. We further identify an invariant submanifold that yields $$\Lambda $$ CDM-like background evolution despite underlying dynamics distinct from General Relativity, providing a geometric origin for cosmic acceleration distinguishable only at the perturbation level. We also derive a first integral on this submanifold, allowing analytic reconstruction of the dynamical connection and uncovering hidden conservation laws. Another key feature we found is that while trivial connections exhibit strong parameter dependence, the nontrivial branches often feature parameter-independent behaviours. We also study the variation of the effective gravitational coupling, $$k_{\text {eff}}$$ , across branches and show how this can be constrained using astrophysical observations, which bridges theoretical viability with observational consistency in a novel way. Applying our framework to the illustrative model $$f(Q)=\alpha Q + \beta (-Q)^n$$ , we find late-time acceleration and $$\Lambda $$ CDM-like behaviour without vacuum energy. Finally, we propose a general route for extending dynamical systems analysis to broader classes of $\textit{f}$($\textit{Q}$) models using the $$m_i$$ -hierarchy method. This framework enables closure for models previously inaccessible to standard approaches and offers a diagnostic tool for identifying structurally viable cosmologies within modified gravity theories.

Jibitesh Dutta

Wompherdeiki Khyllep

Thailand

Saikat Chakraborty

Daniele Gregoris

Khamphee Karwan

A unified dynamical systems framework for cosmology in $\textit{f}$($\textit{Q}$) gravity: generic features across the connection branches