In this work, we investigate three representative new-physics resonances that couple to Standard Model (SM) quarks through flavor-changing interactions involving the top quark. We identify the possible SMEFT operators at the electroweak scale and analyze their phenomenology.

China

Min Huang

Yandong Liu

Hao Zhang

Exploring new resonances with direct top flavor changing interactions * Min Huang and Hao Zhang is supported in part by the National Science Foundation of China (12575114, 12235001, 12075257)

This study constrains the range of in-medium mass modification through a comparison of theoretical calculations with experimental transverse momentum spectra and the yield ratio <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mover accent="true"><mi>p</mi><mo>¯</mo></mover><mo>/</mo><mi>p</mi></mrow></math> of protons and antiprotons. Based on the constrained range and a Gaussian source model with radial flow, the theoretical predictions for the fermion back-to-back correlation (fBBC) of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mover accent="true"><mi>p</mi><mo>¯</mo></mover></mrow></math> pairs at BNL Relativistic Heavy Ion Collider energies are presented. The results reveal a strong sensitivity of the fBBC signal to the assumed source time distribution: a Lorentzian form generates a pronounced high-momentum signal, whereas an <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>α</mi></math>-stable Lévy form leads to a marked low-momentum signal. Moreover, the in-medium mass modification is shown to enhance the yield ratio <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mover accent="true"><mi>p</mi><mo>¯</mo></mover><mo>/</mo><mi>p</mi></mrow></math>. Therefore, events characterized by a larger <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mover accent="true"><mi>p</mi><mo>¯</mo></mover><mo>/</mo><mi>p</mi></mrow></math> ratio are predicted to have a significantly higher probability of exhibiting a detectable fBBC signal. This study may propose a promising new direction for the experimental observation of this phenomenon.

Yong Zhang

Squeezed spectra and back-to-back correlations of protons and antiprotons at energies available at the BNL Relativistic Heavy Ion Collider

We study the equation of state (EoS) of QCD matter in a bottom-up holographic setup that combines an Einstein-Maxwell-dilaton (EMD) sector with an improved Karch-Katz-Son-Stephanov (KKSS) flavor action. In the probe approximation, we perform an inverse reconstruction of the model functions by parameterizing them with neural networks and solving the EMD equations via a differentiable ODE solver (a neural ODE framework), calibrating the model to a reference thermodynamic table for $(2+1)$ -flavor QCD at finite temperature and finite baryon chemical potential. The reconstructed model functions are then parameterized and kept fixed across thermodynamic states. Next, viewing the EMD sector as an effective description of pure Yang-Mills theory, we fix its parameters by fitting the $\mu_B=0$ lattice pure-glue EoS using a hybrid optimization strategy. Finally, we go beyond the probe limit and solve the coupled EMD+KKSS equations with back-reaction, using the pure-glue-calibrated EMD sector as a fixed input and varying the KKSS couplings to compare with the $\mu_B=0$ two-flavor lattice EoS. We find a visible mismatch and a high-temperature behavior in which the back-reacted dimensionless ratios approach a nearly $\beta_1$ -insensitive plateau close to the pure-glue baseline, providing a simple structural diagnostic for the present flavor-sector truncation.

Yutian Deng

Mei Huang

Lin Zhang

Holographic QCD equation of state constrained by lattice QCD: neural-ODE for probe-limit and a back-reaction test * Start-up funding from Sun Yat-sen University (SYSU) (Y. Deng and L. Zhang); National Natural Science Foundation of China (NSFC) (12235016) (L. Zhang and M. Huang) and 12221005 (M. Huang)

Motivated by the observation of the doubly charmed tetraquark $ T_{cc}(3875)^+ $ , we present a systematic study of doubly heavy tetraquarks ( $ T_{QQ'\bar{q}\bar{q}'} $ ) using heavy antiquark-diquark symmetry (HADS) within a constituent quark model. By calibrating model parameters to known hadron spectra and incorporating the effective mass formula, we predict the masses for 38 ground-state tetraquarks with $ cc $ , $ bb $ , and $ bc $ heavy quark pairs, including the non-strange, single-strange, and double-strange configurations with quantum numbers $ J^P = 0^+, 1^+ $ and $ 2^+ $ . Notably, we identify several stable states below the relevant meson-meson thresholds, particularly in the $ bb\bar{q}\bar{q}' $ sector. The explicit connection between the doubly heavy tetraquark and the heavy baryon spectra through HADS reduces model dependence and reveals the fundamental systematics in the heavy-quark hadron landscape.

Liu-Yu Zhang

Tian-Wei Wu

Yong-Liang Ma

Bridging doubly heavy tetraquark mass spectrum with heavy baryons utilizing heavy antiquark-diquark symmetry * The work of Tian-Wei Wu is supported by the National Natural Science Foundation of China (12405108). Yong-Liang Ma is supported in part by the National Science Foundation of China (NSFC) (12347103) and Gusu Talent Innovation Program (ZXL2024363)

We investigated the effect of an isospin chemical potential ( $ \mu_{I} $ ) within the quark-meson model, which approximates quantum chromodynamics (QCD) by modeling low-energy phenomena such as chiral symmetry breaking and phase structure under varying conditions of temperature and chemical potential. Using the functional renormalization group (FRG) flow equations, we calculated the phase diagram in the chiral limit within the two-flavor quark-meson model in a finite $ \mu_{I} $ with $\textit{ρ}$ vector meson interactions. Fluctuation effects significantly decrease the critical chemical potential from the mean-field (MF) value $\mu_{I,{\rm MF}} \gt m_\rho$ to a lower value at which the $\textit{ρ}$ vector meson condensates alongside the chiral condensate once the isospin chemical potential exceeds the critical value $ \mu_{I}^{{\rm{crit}}} $ . This $\textit{ρ}$ condensation was investigated numerically for different meson coupling strengths. The $\textit{ρ}$ meson dominated region is delineated from other phases by a second-order phase transition at lower $ \mu_{I} $ and a first-order transition at slightly higher $ \mu_{I} $ .

Mohammed Osman

Defu Hou

Wentao Wang

United States

Hui Zhang

Functional renormalization group study of $\textit{ρ}$ meson condensate at a finite isospin chemical potential in the quark meson model * Supported in part by the National Key Research and Development Program of China (2022YFA1604900). This work is also partly supported by the National Natural Science Foundation of China (NSFC) (12435009, 12275104). Hui Zhang acknowledges the financial support from the Guangdong Major Project of Basic and Applied Basic Research (2020B0301030008) and the National Natural Science Foundation of China (12047523, 12105107)

We study the impacts of the squeezing effect caused by in-medium mass modification on the Hanbury- Brown–Twiss (HBT) correlation of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>ϕ</mi><mi>ϕ</mi></mrow></math> using a hydrodynamical source. The squeezing effect reduces the influence of transverse flow on the transverse distribution of the <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>ϕ</mi></math> emitting source while expanding the longitudinal source distribution. This trend becomes more noticeable as the transverse momentum increases, resulting in an enlargement of the HBT radii for <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>ϕ</mi><mi>ϕ</mi></mrow></math>. Notably, this enlargement is particularly evident with higher transverse pair momentum. As a result, the HBT radii of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>ϕ</mi><mi>ϕ</mi></mrow></math> increase as the transverse pair momentum increases instead of showing a consistent decrease, showcasing the nonflow behavior of HBT radii in hydrodynamical sources. Both Gaussian fitting and Lévy fitting support the conclusion.

Peng Ru

Hanbury-Brown–Twiss correlation of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>ϕ</mi><mi>ϕ</mi></mrow></math> with in-medium mass modification

We propose a new factorization pattern for tree-level Yang-Mills (YM) amplitudes, where they decompose into a sum of gluings of two lower-point amplitudes by setting specific two-point nonplanar Mandelstam variables within a rectangular configuration to zero. This approach manifests the hidden zeros of YM amplitudes recently identified. Furthermore, by setting specific Lorentz products involving polarization vectors to zero, the amplitudes further reduce to a sum of products of three currents. These novel factorizations provide a fresh perspective on the structure of YM amplitudes, potentially enhancing our understanding and calculation of these fundamental quantities.

New factorizations of Yang-Mills amplitudes

In this work, we prove the new factorization pattern for tree-level Yang-Mills (YM) amplitudes proposed in the companion paper [1]. This pattern reveals a decomposition of amplitudes into a sum of gluings of lower-point amplitudes under specific kinematic constraints, making the hidden zeros of YM amplitudes manifest. Utilizing the Cachazo-He-Yuan (CHY) formalism, we rigorously derive these factorizations by systematically analyzing the contributions of singular solutions to the scattering equations. Through the identification and application of key algebraic identities, we demonstrate how cancellations among terms uncover a recursive structure intricately tied to the hidden zeros. This work not only conclusively validates the proposed factorization but also provides new insights into the geometric and algebraic organization of YM amplitudes within the CHY framework.

Canada

On the new factorizations of Yang-Mills amplitudes

We apply the method of quantum chromodynamics (QCD) sum rules to study the <math><mi>q</mi><mi>c</mi><mover><mi>q</mi><mo>¯</mo></mover><mover><mi>c</mi><mo>¯</mo></mover></math> tetraquark states with the exotic quantum number <math><msup><mi>J</mi><mrow><mi>P</mi><mi>C</mi></mrow></msup><mo>=</mo><msup><mn>3</mn><mrow><mo>−</mo><mo>+</mo></mrow></msup></math>, and extract the mass of the lowest-lying state to be <math><msubsup><mn>4.49</mn><mrow><mo>−</mo><mn>0.41</mn></mrow><mrow><mo>+</mo><mn>0.45</mn></mrow></msubsup><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>. To construct the relevant tetraquark currents we need to explicitly add the covariant derivative operator. Our systematic analysis of these interpolating currents indicates that: (a) this state readily decays into the <math><mi>P</mi></math>-wave <math><mo>[</mo><mi>ρ</mi><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>]</mo><mo>/</mo><mo>[</mo><mi>ω</mi><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>]</mo></math> channel but not into the <math><mo>[</mo><mi>ρ</mi><msub><mi>χ</mi><mrow><mi>c</mi><mn>2</mn></mrow></msub><mo>]</mo><mo>/</mo><mo>[</mo><mi>ω</mi><msub><mi>χ</mi><mrow><mi>c</mi><mn>2</mn></mrow></msub><mo>]</mo><mo>/</mo><mo>[</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><msub><mi>f</mi><mn>2</mn></msub><mo>(</mo><mn>1270</mn><mo>)</mo><mo>]</mo></math> channels, and (b) it readily decays into the <math><mo>[</mo><msup><mi>D</mi><mo>*</mo></msup><msubsup><mover><mi>D</mi><mo>¯</mo></mover><mn>2</mn><mo>*</mo></msubsup><mo>]</mo></math> channel but not into the <math><mi>P</mi></math>-wave <math><mo>[</mo><msup><mi>D</mi><mo>*</mo></msup><msup><mover><mi>D</mi><mo>¯</mo></mover><mo>*</mo></msup><mo>]</mo></math> channel.

Hong-Zhou Xi

Hua-Xing Chen

Wei Chen

T. G. Steele

Dan Zhou

Charmoniumlike states with the exotic quantum number <math><mrow><msup><mrow><mi>J</mi></mrow><mrow><mi>P</mi><mi>C</mi></mrow></msup><mo>=</mo><msup><mrow><mn>3</mn></mrow><mrow><mo>−</mo><mo>+</mo></mrow></msup></mrow></math>

The attenuation length of the muon content in extensive air showers provides important information regarding the generation and development of air showers. This information can be used not only to improve the description of such showers but also to test fundamental models of hadronic interactions. Using data from the LHAASO-KM2A experiment, the development of the muon content in high-energy air showers was studied. The attenuation length of muon content in the air showers was measured from experimental data in the energy range from 0.3 to 30 PeV using the constant intensity cut method. By comparing the attenuation length of the muon content with predictions from high-energy hadronic interaction models (qgsjet-II-04, sibyll 2.3d, and epos-lhc), it is evident that LHAASO results are significantly shorter than those predicted by the first two models (qgsjet-II-04 and sibyll 2.3d) but relatively close to those predicted by the third model (epos-lhc). Thus, the LHAASO data favor the epos-lhc model over the other two models. The three interaction models confirmed an increasing trend in the attenuation length as the cosmic-ray energy increases.

Zhen Cao

Germany

Ireland

F. Aharonian

 Axikegu

Y. X. Bai

Y. W. Bao

D. Bastieri

X. J. Bi

Y. J. Bi

W. Bian

Russia

A. V. Bukevich

Q. Cao

W. Y. Cao

Zhe Cao

J. Chang

J. F. Chang

A. M. Chen

E. S. Chen

H. X. Chen

Liang Chen

Lin Chen

Long Chen

M. J. Chen

M. L. Chen

Q. H. Chen

S. Chen

S. H. Chen

S. Z. Chen

T. L. Chen

Y. Chen

N. Cheng

Y. D. Cheng

Hong Kong

M. C. Chu

M. Y. Cui

S. W. Cui

X. H. Cui

Y. D. Cui

B. Z. Dai

H. L. Dai

Z. G. Dai

 Danzengluobu

X. Q. Dong

K. K. Duan

J. H. Fan

Y. Z. Fan

J. Fang

J. H. Fang

K. Fang

C. F. Feng

H. Feng

L. Feng

S. H. Feng

X. T. Feng

Y. Feng

Y. L. Feng

France

S. Gabici

B. Gao

C. D. Gao

Q. Gao

W. Gao

W. K. Gao

M. M. Ge

T. T. Ge

L. S. Geng

G. Giacinti

G. H. Gong

Q. B. Gou

M. H. Gu

F. L. Guo

J. Guo

X. L. Guo

Y. Q. Guo

Y. Y. Guo

Y. A. Han

O. A. Hannuksela

M. Hasan

H. H. He

H. N. He

J. Y. He

Y. He

Y. K. Hor

B. W. Hou

C. Hou

X. Hou

H. B. Hu

Q. Hu

S. C. Hu

C. Huang

D. H. Huang

T. Q. Huang

W. J. Huang

X. T. Huang

X. Y. Huang

Y. Huang

Y. Y. Huang

X. L. Ji

H. Y. Jia

K. Jia

H. B. Jiang

K. Jiang

X. W. Jiang

Measurement of attenuation length of the muon content in extensive air showers from 0.3 to 30 PeV with LHAASO