Search

The anomalous magnetic (MDM) and electric (EDM) dipole moments of the $\tau$ lepton serve as crucial indicators of new physics beyond the Standard Model. Leveraging azimuthal angular asymmetry as a novel tool in ultraperipheral collisions (UPCs), we attain unparalleled precision in the study of these key properties. Driven by the highly linear polarization of coherent photons, this method uniquely enables both the MDM and EDM to contribute to the $\cos2\phi$ angular distribution in similar magnitudes. Importantly, our approach substantially narrows the parameter space, excluding more than half of it compared to expected UPC-based measurements reliant solely on the total cross-section. This method not only provides improved constraints but also minimizes the need for additional theoretical assumptions., Comment: 8 pages, 3 figures, published version in SCIENCE CHINA Physics, Mechanics & Astronomy

Equivalence theorem is a cornerstone of Standard Model Effective Field Theory, ensuring the equality of the S-matrix and reducing redundant operators. The Warsaw basis and the SILH basis of dimension-6 operators have been shown to be equivalent and connected through equations of motion and field redefinitions, but how to connect the two operator bases in interpreting data is not clear. Through a unitarity analysis we verify that the two operator bases are indeed equivalent, but achieved in a non-trivial way., Comment: 5 pages, 1 figure

The determination of the $Zb\bar{b}$ coupling in experiments has been a long-standing challenge, as the limited precision of off $Z$-pole measurements at the LEP has resulted in two degenerate solutions remained to be resolved. In this paper, we propose a novel method to probe the $Zb\bar{b}$ coupling by measuring the forward-backward asymmetry of the bottom quark, $A^{b}_\text{{FB}}$, in the $b\bar{b}$ system of the $e^+ e^- \to b \bar{b} \gamma$ and/or $e^+ e^- \to b \bar{b} g$ processes at the $Z$-pole of future lepton colliders. The additional hard photon or light jet radiation can mimic the energy scanning of the $e^+e^-\to b\bar{b}$ process, and the $A_{\rm FB}^b$ distribution from the $\gamma$-$Z$ interference process is linearly sensitive to the $Zb\bar{b}$ coupling. By combining the expected measurements of $R^0_b$ and $A^{0,b}_\text{{FB}}$ at the $Z$-pole at the CEPC, the $A^{b}_\text{{FB}}$ distributions can break the degeneracy observed at the LEP, leading to a unique determination of the $Zb\bar{b}$ coupling through $Z$-pole running alone., Comment: 4 pages, 6 figures

In order to reveal the coupling effect among the chemical activity and the hydraulic seepage as well as the mechanical properties, a constitutive theoretical framework considering the chemical activity for saturated porous media is derived from the mixture theory incorporated with the chemical thermodynamics. First, to highlight the important role of porosity in the hydro-mechanical-chemical multi-field coupling mechanism, the solid strain is divided into the porosity-dependent skeleton strain, the matrix strain and the mass-exchange strain. The stress and strain state variables are determined from the energy-conjugated form of the energy balance equation for establishing constitutive equations. Second, under infinitesimal case, general elastic constitutive equations including the relationship between mass fraction and its chemical potential are expressed by the free energy potential. Plastic model and the constitutive equation of thermodynamic flux and force are derived from the dissipative potential. Finally, under the guide of this theoretical framework, the complete swelling constitutive models in the confined compression are established for bentonite. The corresponding governing equations are formulated for multi-field two-phase saturated porous media. Compared with the experimental data, the proposed model can well reflect the chemical and mechanic coupling characteristics of representative elementary volume in the different NaCl concentrations of solution for saturated bentonite., Comment: 64 pages, 9 figures

Confining gauge dynamics in dark sector is promising to provide dark matter with a mass in the range of sub-GeV to GeV. These dark sectors consist of composite particles, such as dark baryons and dark mesons, that are neutral under the standard-model charge. Dark photon is introduced as a portal matter between the dark sector and the standard-model sector in order to alleviate cosmological problems, and dark hadrons are produced through the same dark photon at accelerator-based experiments. As dark vector mesons and dark pions have the similar masses, dark vector mesons can be long-lived particles, which will be explored by far-detector experiments. In this study, we study the future prospect of the LHC forward-detector experiments, FASER2 and FACET, for exploring the dark vector mesons. When dark photon is heavier than dark pions, the LHC forward-detector searches can be comparable to DarkQuest, and the invisible decay searches of dark photons can also explore the same parameter space. Meanwhile, when dark photon is lightest in the dark sector, their future prospect will be comparable to the visible decay searches for dark photons at LHCb, Belle-II, and HPS., Comment: Published version

We study the determination of the top-quark mass using leptonic observables in t-channel single top-quark production at the LHC. We demonstrate sensitivity of transverse momentum of the charged lepton on the input top-quark mass. We present predictions at next-to-next-to-leading order (NNLO) in QCD with narrow width approximation and structure function approach. Further corrections due to parton shower and hadronization, non-resonant and non-factorized contributions are discussed. To reduce impact of SM backgrounds we propose to use the charge weighted distribution for the measurement, i.e., differences between distributions of charged lepton with positive and negative charges. By modeling both signal and background processes, we found the projections for (HL-)LHC to be promising, with a total theoretical uncertainty on the extracted top-quark mass of about 1 $\sim$ 2 GeV., Comment: 29 pages, 8 figures; version to appear on JHEP

This paper is devoted to the primary spectro-polarimetric observation performed at the New Vacuum Solar Telescope of China since 2017, and our aim is to precisely evaluate the real polarimetric accuracy and sensitivity of this polarimetry by using full Stokes spectro-polarimetric observations of the photospheric line Fe I 532.4 nm. In the work, we briefly describe the salient characteristic of the NVST as a polarimeter in technology and then characterize its instrumental polarization based on the operation in 2017 and 2019. It is verified that the calibration method making use of the instrumental polarization calibration unit (ICU) is stable and credible. The calibration accuracy can reach up to 3$\times 10^{-3}$ . Based on the scientific observation of the NOAA 12645 on April 5th, 2017, we estimate that the residual cross-talk from Stokes $I$ to Stokes $Q$, $U$ and $V$, after the instrumental polarization calibration, is about 4$\times10^{-3}$ on average, which is consistent with the calibration accuracy and close to the photon noise. The polarimetric sensitivity (i.e., the detection limit) for polarized light is of the order of $10^{-3}$ with an integration time over 20 seconds. Slow modulation rate is indeed an issue for the present system. The present NVST polarimeter is expected to be integrated with an high-order adaptive optics system and a field scanner to realize 2D magnetic field vector measurements in the following instrumentation update., Comment: 17pages, 9 figures,accepted by Research in Astronomy and Astrophysics