2025粒子物理标准模型及新物理精细计算研讨会

We compute all planar two-loop six-point massless integrals via canonical differential equations. The integral basis with uniform transcendentality is determined via the D-dimensional upgrading of dual conformal integrals and the Baikov representation analysis. The analytic boundary values are determined and all planar two-loop six-point massless planar are calculated as iterative integrals. This is a milestone of Feynman integral computation, and paves the way for two-loop six-point amplitude studies and the NNLO four-final-state precision computations.

In this talk, I will present a Leptogenesis scenario, which does not need primordial B-L asymmetry in the early Universe, and does not need the existence of right-handed neutrinos. In this case, the baryon asymmetry is generated by the requirement that the electron Yukawa interction enters thermal equilibrium after the quench of the electroweak sphaleron.

We introduce a novel search strategy for heavy top-philic resonances that induce new contributions to four-top production at the LHC. We capitalize on recent advances in top-tagging performance to demonstrate that the final state, that is expected to be boosted based on current limits, can be fully reconstructed and exploited. Notably, our approach promises bounds on new physics cross sections that are a few to 60 times stronger than those obtained with existing searches showcasing its unprecedented effectiveness in probing top-philic new physics.

The study of exotic gauge bosons beyond the Standard Model have always been of great interest. Future muon colliders will have a significant advantage in discovering exotic particles. We study the properties of $Z^\prime$ boson with the process of $\mu^+ \mu^- \rightarrow q \bar{q}$, $\mu^+ \mu^- \rightarrow l^+ l^-$, $\mu^+ \mu^- \rightarrow Z H$ and $\mu^+ \mu^- \rightarrow W^+ W^-$. Through studying the $\mu^+ \mu^- \to W^{\prime +} W^{\prime -} \to e^+ e^- n_e \bar{n}_e$ process, we explore the properties of $W^\prime$ in the alternative left-right model as well.

Here we discuss the 3pt celestial amplitude of two massive scalars and one massless scalar. In the massless limit $m\to 0$ for one of the massive scalars, the gamma function $\Gamma(1-\Delta)$ appears. By requiring the resulting amplitude to be well-defined, that is it goes to the 3pt amplitude of arXiv:2312.08597, the scaling dimension of this massive scalar has to be conformally soft $\Delta \to 1$. The pole $1/(1-\Delta)$ coming from $\Gamma(1-\Delta)$ is crucial for this massless limit. Without it the resulting amplitude would be zero. The phase factors in the massless limit of massive conformal primary wave functions, discussed in arXiv:1705.01027, plays an import and consistent role in the celestial massive amplitudes. Furthermore, the subleading orders $m^{2n}$ can also contribute poles when the scaling dimension is analytically continued to $\Delta=1-n$ or $\Delta = 2$. This consistent massless limit only exists for dimensions belonging to the generalized conformal primary operators $\Delta \in 2-\mathbb{Z}_{\geq 0}$ of massless bosons.

The integration-by-parts (IBP) reduction is one of the bottleneck steps in the evaluation of multi-loop Feynman integrals. NeatIBP is a program based on the syzygy method for IBP reduction. It generates much smaller IBP systems compared to traditional Laporta's algorithm, which helps reduce the computation cost of IBP reduction. In this talk, I will present the new version of NeatIBP. It is with multiple useful new features. These features include: the automated interface with the popular Feynman integral reduction software Kira, the implementation of IBP reduction using the idea of spanning cuts, the algorithm of syzygy vector simplification, and more. I will also introduce some recent works in amplitude computation that is supported by NeatIBP.

We evaluate thethree-loop five-pointpentagon-box-box massless integral family in the dimensional regularization scheme, via canonical differential equation. We use tools fromcomputational algebraic geometryto enable the necessary integral reductions. The boundary values of the differential equation are determinedanalyticallyin the Euclidean region. To express the final result, we introduce anew representation of weight six functionsin terms of one-fold integrals over the product of weight-three functions with weight-two kernels that are derived from the differential equation.Our work paves the way to the analytic computation of three-loop multi-leg Feynman integrals.

The scalar mesons are established for a long time, but their nature is still an open question. In this paper, we investigate the potential of categorizing their $SU(3)_f$ representations via $J/\psi \to SV $and $\gamma S$, offering a criterion that may illuminate this issue. Here, $S (V)$ denotes scalar (vector) mesons. Using the $SU(3)_f$ symmetry with the current data, we find that $f_0(500)$ and $f_0(980)$ are mostly made of singlet and octet $SU(3)_f$ representations, respectively, with the singlet-octet mixing angle of $\theta=(82.9\pm 4.4)^{\circ}$. This conclusion is consistent with the caculations of the quark-antiquark ($q\bar{q}$) hypothesis. For the scalar mesons in the range of 1-2 GeV, we discuss the mixings between qq¯ and glueballs. Our numerical results suggest that $f_0(1710)$ is likely composed of the scalar glueball. We urge our experimental colleagues to measure $J/\psi \to \rho a_0(980, 1450, 1710), K^∗(892)^{\pm} K^∗(700, 1430, 1950)^{\mp}$ and $\omega f_0(500)$, which provide useful information in the SU(3)f analysis.

In hidden-sector models, axion-like particles (ALPs) can couple to heavy neutral
leptons (HNLs), leading to rich phenomenologies. We study ALPs produced from D- and B-meson decays via quark-favor-violating couplings, and decaying exclusively into a pair of HNLs which mix with active neutrinos. The ALP can be either short- or long-lived, depending on the masses of the ALP and the HNL, as well as the corresponding coupling strength. Such GeV-scale HNLs are necessarily long-lived given the current bounds on their mixing parameters. We assess the sensitivities of the LHC far detectors, SHiP, and Belle II, to the long-lived HNLs in such theoretical scenarios. We fnd that for currently allowed values of the ALP couplings, most of the LHC experiments can probe the active-sterile-neutrino mixing parameters multiple orders of magnitude beyond the present bounds, covering large parameter region targeted with the type-I seesaw mechanism, while the Belle II experiment can test the mixing parameters up to two orders of magnitude below the existing limits.

Within the framework of Non-Relativistic Quantum Chromodynamics (NRQCD) factorization,
we calculate the next-to-leading order (NLO) perturbative QCD corrections to the form factors for
the semileptonic decays of Bcinto J/ψ via (axial-)vector and (axial-)tensor currents. We obtain the
complete analytical results for the form factors up to NLO, and provide their asymptotic expressions
in the hierarchical heavy quark limit. The NLO corrections are found to be both significant and
convergent in the relatively small squared transfer momentum （q2）region, while also reducing the
dependence on the renormalization scale µ. Finally, the theoretical predictions for Bc→ J/ψ form
factors over the full q2 range are provided.

X（3872），作为四夸克的候选者，其产生和衰变等性质被实验和理论广泛研究。我们在NRQCD框架下，通过Higgs和弱玻色子衰变研究了双粲紧致四夸克态的间接产生机制，并分别在LHC和CEPC上预言了其分支比和产生率等。基于共线因子化，利用两种碎裂函数方法，我们对全粲四夸克态的间接产生性质也进行了深入的研究。通过此报告将详细介绍近期我们关于四夸克态间接产生的理论研究工作。

We investigate three intriguing anomalies within the framework of the general next-to-minimal supersymmetric standard model. These anomalies include a significant deviation of the experimental results for the muon anomalous magnetic moment from its standard model prediction, with a confidence level of 5.1σ; a joint observation by the CMS and ATLAS Collaborations of a diphoton excess with a local significance of 3.1σ in the invariant mass distribution around 95.4 GeV; and a reported excess in the bb ̄ production at the Large Electron-Positron Collider with a local significance of 2.3σ. Through analytical and numerical analyses, we provide unified interpretations across an extensive parameter space that remain consistent with current experimental restrictions from data on the Higgs boson at 125 GeV, B-physics measurements, and dark matter observables, as well as existing searches for supersymmetry and extra Higgs bosons. We attribute the muon anomaly to loops involving muon-smuon-neutralino and muon- sneutrino-chargino interactions, while attributing the diphoton and bb ̄ excesses to the resonant production of a singlet-dominated scalar. These proposed solutions are poised for experimental tests at the high- luminosity LHC and future linear colliders.

Vector-like quarks (VLQs) are ubiquitous in many new physics models, such as grand unified theory, composite Higgs models, extra dimension theory, and so on. In minimal VLQ models, only seven types of representations can induce the mixing with standard model quarks. In non-minimal VLQ models, we can also introduce new scalar fields. The VLQ models can lead to rich phenomenology in electroweak precision observables, Higgs physics, flavour physics. In this talk, we will summarize our previous studies on the STU parameters, Higgs physics, and muon g-2 in the VLQ extended models.