We propose a novel method to probe gluon linear polarization via energy correlations in hard scattering processes. This approach exploits the characteristic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>cos</mi><mn>2</mn><mi>ϕ</mi></math> azimuthal modulation in single- and two-point energy correlations within jets initiated by polarized gluons. In contrast to conventional techniques that rely on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>k</mi><mi>t</mi></msub></math> resummation or intricate jet substructure observables, our method offers a theoretically robust and experimentally accessible avenue for gluon polarimetry. We perform an all-order analysis within the Ciafaloni-Catani-Fiorani-Marchesini formalism, incorporating coherent branching effects to achieve improved precision. Our predictions can be tested at current and future facilities, including the LHC, RHIC, HERA, and the EIC.

Yu-Kun Song

Shu-Yi Wei

Lei Yang

Jian Zhou

Gluon Polarimetry with Energy-Energy Correlators

We propose a novel strategy to systematically isolate the nucleon’s intrinsic nonperturbative three-dimensional structure by employing zero jettiness to suppress initial-state radiation in transverse-momentum-dependent observables. Applying this method to transverse single spin asymmetries (SSAs) in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>W</mi></mrow><mrow><mo>±</mo></mrow></msup></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mn>0</mn></msup></math> boson production at Relativistic Heavy Ion Collider (RHIC), we demonstrate a substantial enhancement of the asymmetry signal (e.g., by 115% for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>W</mi><mo>−</mo></msup></math> SSA at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>q</mi></mrow><mrow><mo>⊥</mo></mrow></msub><mo>=</mo><mn>5</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>). We show that this enhancement yields a substantial net gain in experimental sensitivity—even after accounting for the statistical cost of the veto—facilitating a more definitive test of the predicted Sivers function sign change. We further explore its applicability to spin-dependent measurements at the Electron-Ion Collider. Our analysis is formulated within a joint resummation framework that systematically resums large logarithms associated with both the veto scale and the gauge boson’s transverse momentum.

China

Shen Fang

Shuo Lin

Ding Yu Shao

Nucleon Tomography with Zero Jettiness

We present an investigation on cosmological implications resulting from spontaneous dark $ S U(2)_d $ symmetry breaking in conjunction with the Witten effect. Furthermore, we examine the mass of hidden monopoles generated by phase transition as well as the impact of axion-monopole interactions on the axion mass. Following spontaneous breaking of the PQ symmetry, axions emitted by cosmic strings or domain walls as well as hidden monopoles generated during this transition may collectively contribute to the observed dark matter relic density. Additionally, the stochastic gravitational wave background generated by sub-GeV phase transitions and by the decay of axionic domain walls formed during sub-ZeV phase transitions could account for the low-frequency gravitational wave signals detected by PTA experiments.

Ruiyu Zhou

Ligong Bian

Gravitational waves and dark matter with Witten effect * Supported by the National Key Research and Development Program of China (2021YFC2203004). Ruiyu Zhou is supported by the National Natural Science Foundation of China (12305109, 12147102), Chongqing Natural Science Foundation project (CSTB2022NSCQ-MSX0534), and Science and Technology Research Project of Chongqing Municipal Education Commission (KJQN202300614). Ligong Bian is supported by the National Natural Science Foundation of China (12322505, 12347101). Ligong Bian also acknowledges Chongqing Natural Science Foundation (CSTB2024NSCQ-JQX0022) and Chongqing Talents: Exceptional Young Talents Project (cstc2024ycjhbgzxm0020).

The neutrino floor, a theoretical sensitivity limit for dark matter (DM) direct detection, is being redefined as the boundary of a dynamic ''neutrino fog,'' where neutrino signals become inevitable, obscuring DM detection due to statistical and systematic uncertainties. This study provides the first site-specific analysis of the neutrino floor at China Jinping Underground Laboratory (CJPL), leveraging its unique geographic and environmental characteristics. We quantify how CJPL’s suppressed atmospheric neutrino flux (approximately 30% lower than that of Laboratori Nazionali del Gran Sasso (LNGS)) reshapes the neutrino floor, thereby enabling improved sensitivity to high-mass WIMPs (mass > 10 GeV). Using a gradient-based framework, we derive the CJPL’s neutrino floor and estimate the detection prospects for the PandaX-xT experiment. Our results demonstrate that a 500 tonne-year exposure with PandaX-xT could reach the floor, probing spin independent cross-sections down to $ \sigma_{n}\sim 3\times 10^{-49}\; {\rm{cm}}^2$ at a DM mass of 70 GeV/$\textit{c}$ $^{2}$.

Yingjie Fan

Xuewen Liu

Ning Zhou

Characterizing the CJPL’s site-specific neutrino floor as the neutrino fog boundary * Xuewen Liu is supported by the Project of Shandong Province Higher Educational Science and Technology Program (2022KJ271). Ning Zhou is supported by National Science Foundation of China (12325505)

In this study, we investigate the $R^2$ corrections to the dissociation of heavy quarkonium in the Gauss-Bonnet gravitational background. We analyze the impact of the Gauss-Bonnet parameter $\lambda_{\rm GB}$ on the spectral function of charmonium and bottomonium and examine the effect of $\lambda_{\rm GB}$ on the dissociation of heavy quarkonium. Our results show that $\lambda_{\rm GB}$ reduces the peak height and increases the peak width of the spectral function, suggesting that $\lambda_{\rm GB}$ enhances the dissociation of heavy quarkonium. We also discuss the variation in the dissociation of heavy quarkonium with the ratio of shear viscosity to entropy density and observe that the dissociation is easier in more perfect plasma. Additionally, we observe that the temperature decreases the peak height and widens the peak, thereby accelerating the dissociation.

Zhou-Run Zhu

Manman Sun

Rui Zhou

Jinzhong Han

$\textit{R}$ $^{2}$ corrections to holographic heavy quarkonium dissociation * Rui Zhou supported by the Science and Technology Development Plan Project of Henan Province, China (242102230085), the National Natural Science Foundation of China (12404470), the High Level Talents Research and Startup Foundation Projects for Doctors of Zhoukou Normal University, China (ZKNUC2023017). Manman Sun supported by the National Natural Science Foundation of China (12305076). Zhou-Run Zhu supported by the High Level Talents Research and Startup Foundation Projects for Doctors of Zhoukou Normal University, China (ZKNUC2023018)

In this Letter, we advocate a set of novel azimuthal-angle-related observables associated with exclusive hadron production from two-photon fusion at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> colliders, taking the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi><mi>γ</mi><mo stretchy="false">→</mo><mi>π</mi><mi>π</mi></math> as a benchmark process. As a direct consequence of the linearly polarized quasireal photons emitted off the electron and positron beams, the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>cos</mi><mn>2</mn><mi>ϕ</mi></math> azimuthal asymmetry in dipion production is predicted within the transverse-momentum-dependent factorization framework. In numerical analysis, we take the helicity amplitudes of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi><mi>γ</mi><mo stretchy="false">→</mo><mi>π</mi><mi>π</mi></math> determined from the partial wave solutions in dispersion relation as input, and find that the predicted <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>cos</mi><mn>2</mn><mi>ϕ</mi></math> azimuthal modulation may reach 40% for the typical kinematical setup of Belle 2 and BESIII experiments. Future accurate measurement of this azimuthal asymmetry may facilitate the direct extraction of the relative phase between two helicity amplitudes with photon helicity configurations <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>+</mo><mo>+</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>+</mo><mo>−</mo></math>. This knowledge provides a valuable input for the dispersive determination of the hadronic light-by-light contributions.

Yu Jia

Ya-jin Zhou

Novel Azimuthal Observables from Two-Photon Collision at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> Colliders

In this work we study the tau-function <math altimg='si2.svg'><msup><mrow><mi>Z</mi></mrow><mrow><mn>1</mn><mi>D</mi></mrow></msup></math> of the KP hierarchy specified by the topological 1D gravity. As an application, we present two types of algorithms to compute the orbifold Euler characteristics of the moduli spaces <math altimg='si1.svg'><msub><mrow><mover accent='true'><mrow><mi mathvariant='script'>M</mi></mrow><mo>&#8254;</mo></mover></mrow><mrow><mi>g</mi><mo>,</mo><mi>n</mi></mrow></msub></math> of stable curves. The first is to use (fat or thin) topological recursion formulas emerging from the Virasoro constraints for <math altimg='si2.svg'><msup><mrow><mi>Z</mi></mrow><mrow><mn>1</mn><mi>D</mi></mrow></msup></math>; and the second is to use a formula for the connected <italic>n</italic>-point functions of a KP tau-function in terms of its affine coordinates on the Sato Grassmannian. This is a sequel to an earlier work <cross-ref refid='br0340' id='crf0030'>[34]</cross-ref>.

Zhiyuan Wang

Topological 1D gravity, KP hierarchy, and orbifold Euler characteristics of <math altimg='si1.svg'><msub><mrow><mover accent='true'><mrow><mi mathvariant='script'>M</mi></mrow><mo>&#8254;</mo></mover></mrow><mrow><mi>g</mi><mo>,</mo><mi>n</mi></mrow></msub></math>

The axion-gluon coupling can be constrained directly through hard exclusive processes at the LHC. Specifically, we study the associated production of a long-lived axion with a <math><msup><mi>ρ</mi><mn>0</mn></msup></math> meson in ultraperipheral <math><mi>A</mi><mi>A</mi></math> collisions and in <math><mi>p</mi><mi>p</mi></math> collisions. With the axion escaped from the detector, the final state is characterized by a monohadron signature. The main background in our analysis originates from the <math><msup><mi>ρ</mi><mn>0</mn></msup><mo>+</mo><msup><mi>π</mi><mn>0</mn></msup></math> process, where the photons from the <math><msup><mi>π</mi><mn>0</mn></msup></math> decay are undetected due to limited detector performance. Our analysis yields an exclusion limit of the axion-gluon coupling that is comparable to the limit obtained from the monojet process at the LHC.

Shou-shan Bao

Wenhai Gao

Hong Zhang

Constraining axion-gluon coupling in monohadron processes

We propose to detect signals from quark orbital angular momentum (OAM) through exclusive <math><msup><mi>π</mi><mn>0</mn></msup></math> production in electron- (longitudinally polarized) proton collisions. Our analysis demonstrates that the <math><mi>sin</mi><mn>2</mn><mi>ϕ</mi></math> azimuthal angular correlation between the transverse momentum of the scattered electron and the recoil proton serves as a sensitive probe of quark OAM. Additionally, we present a numerical estimate of the asymmetry associated with this correlation for the kinematics accessible at the Electron-Ion Colliders in the U.S. and China. This study aims to pave the way for the first experimental study of quark OAM in relation to the Jaffe-Manohar spin sum rule.

United States

Shohini Bhattacharya

Duxin Zheng

Probing the Quark Orbital Angular Momentum at Electron-Ion Colliders Using Exclusive <math><mrow><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup></mrow></math> Production

We explore the impact of initial state soft gluon radiations on the azimuthal angle asymmetries in photo-production of hard di-jet via coherent diffraction in ultraperipheral heavy ion collisions, as well as in electron-proton (ep) and electron-nucleus (eA) collisions. The primary production mechanism is identified as the diffractive production of two hard jets, accompanied by a collinear gluon emission along the beam direction. In contrast, the diffractive exclusive di-jet production, where the initial state radiation is absent, is suppressed due to color transparency. Our analysis shows that azimuthal asymmetries, traditionally attributed to final state gluon emissions, are reduced by the presence of initial state radiations. The sensitivity of azimuthal asymmetries to both initial and final state radiations suggests that they could provide novel insights into the mechanisms of di-jet production in diffractive processes.