We present analytic results for one of two types of planar QED two-loop integrals for $μe$ scattering including finite lepton masses. No approximations are made, such that the results are valid not only in the limit of a small electron mass. The results are expressed in terms of multiple polylogarithms with algebraic function arguments in a representation which allows for fast numerical evaluation in the physical phase-space.
The QCD$\times$QED factorization is studied for two-body non-leptonic and semi-leptonic $B$ decays with heavy-light final states. These non-leptonic decays, like $\bar{B}^0_{(s)}\to D^+_{(s)} π^-$ and $\bar{B}_d^0 \to D^+ K^-$, are among the theoretically cleanest non-leptonic decays as penguin loops do not contribute and colour-suppressed tree amplitudes are suppressed in the heavy-quark limit or even completely absent. Advancing the theoretical calculations of such decays requires therefore also a careful analysis of QED effects. Including QED effects does not alter the general structure of …
The explanation for lepton $g-2$ anomalies is provided with the nonlocal QED which is the simple extension of the standard model. This solution is based on the same gauge symmetry as QED without introducing any new particles and interactions. The correlation functions in the nonlocal strength tension and lepton-photon interaction make it possible to explain the discrepancies of both $Δa_μ$ and $Δa_e$. With the same approach, the discrepancy of anomalous magnetic moment of $τ$ lepton from standard model is estimated in the range $1.19\times10^{-5}$ to $3.21\times10^{-3}$ which is covered by the…
We showcase the calculation of the master integrals needed for the two loop mixed QCD-QED virtual corrections to the neutral current Drell-Yan process $(q\bar{q}\rightarrow l^+ l^-)$. After establishing a basis of 51 master integrals, we cast the latter into canonical form by using the Magnus algorithm. The dependence on the lepton mass is then expanded such that potentially large logarithmic contributions are kept. After determining all boundary constants, we give the coefficients of the Taylor series around four space-time dimensions in terms of generalized polylogarithms up to weight four.
The master integrals for the mixed QCD-QED two-loop virtual corrections to the charged-current Drell-Yan process $q\bar{q}^{\prime} \rightarrow \ell ν$ are computed analytically by using the differential equation method. A suitable choice of master integrals makes it successful to cast the differential equation system into the canonical form. We keep the dependence on charged lepton mass in the building of differential equations and then expand the system against the ratio of small charged lepton mass to large $W$-boson mass. In such a way the final results will contain large logarithms of the…
Tenth-Order QED Contribution to the Lepton Anomalous Magnetic Moment -- Sixth-Order Vertices Containing an Internal Light-by-Light-Scattering Subdiagram
This paper presents a new method of numerical computation of the QED contributions to the electron anomalous magnetic moment which arises from Feynman graphs containing electron and photon lines and not containing electron loops. The method consists of two parts. The first part is the forest-like subtraction formula that removes all ultraviolet and infrared divergences in each Feynman graph point-by-point in Feynman-parametric space. The second part is the importance sampling Monte-Carlo algorithm with the probability density function that is constructed for each Feynman graph individually. Th…
McMule is a framework for fully differential higher-order QED calculations of scattering and decay processes involving leptons. It keeps finite lepton masses, which regularises collinear singularities. Soft singularities are treated with dimensional regularisation and using FKS$^\ell$ subtraction. We describe the implementation of the framework in Fortran 95, list the processes that are currently implemented, and give instructions on how to run the code. In addition, we present new phenomenological results for muon-electron scattering and lepton-proton scattering, including the dominant NNLO c…
The three-loop QED mass-dependent contributions to the $g-2$ of each of the charged leptons with two internal closed fermion loops, sometimes called $A^{(6)}_3\left(\frac{m_1}{m_2}, \frac{m_1}{m_3}\right)$ in the $g-2$ literature, is revisited using the Mellin-Barnes (MB) representation technique. Results for the muon and $τ$ lepton anomalous magnetic moments $A^{(6)}_{3,μ}$ and $A^{(6)}_{3,τ}$, which were known as series expansions in the lepton mass ratios up to the first few terms only, are extended to their exact expressions. The contribution to the anomalous magnetic moment of the electro…
We scrutinise the ability of the primary QED final-state resummation tools, combined with electroweak virtual corrections, to reproduce the exact next-to-leading order electroweak calculation in the four-charged-lepton final state. We further examine the dependence of the findings on the lepton-photon dressing-cone size as well as the resonance identification strategy. Overall we find excellent agreement with the fixed-order result, but partial differences not directly connected with resummation-induced higher-order effects at the few-percent level are observed in some cases, which are relevan…
This paper describes a computation of a part of the QED contribution to the electron anomalous magnetic moment that was performed by the author with the help of a supercomputer. The computed part includes all 5-loop QED Feynman graphs without lepton loops. The calculation has led to the result $A_1^{(10)}[\text{no lepton loops}]=6.793(90)$ that is slightly different than the value $7.668(159)$ presented by T. Aoyama, T. Kinoshita, and M. Nio in 2018. The discrepancy is about $4.8σ$. The computation gives the first independent check for that value. A shift in the fine-structure constant predict…
We discuss QED radiative corrections at first and second order for the parity violating asymmetry $A_\text{PV}$ in elastic electron proton scattering. A measurement of $A_\text{PV}$ is planned at low energies and with high precision by the forthcoming P2 experiment at the new MESA facility in Mainz. Bremsstrahlung leads to a shift of the momentum transfer $Q^2$ which affects the determination of the weak charge of the proton.
We construct a multiscalar and non-renormalizable model where the $\mathbf{S}_{3}$ flavor symmetry drives mainly the Yukawa couplings. In the quark sector, the Nearest Neighbor Interaction (NNI) textures are behind the CKM mixing matrix so that this is fitted in good agreement with the last available results. In the lepton sector, an almost diagonal charged lepton mass matrix and extended Fritzsch mass textures in the effective neutrino mass matrix, that comes from the type II see-saw mechanism, provide consistent values for the mixing angles where the normal hierarchy is favored. The model pr…
We present a comprehensive analysis of neutrino mass and lepton mixing in theories with $A_4$ modular symmetry, where the only flavon field is the single modulus field $τ$, and all masses and Yukawa couplings are modular forms. Similar to previous analyses, we discuss all the simplest neutrino sectors arising from both the Weinberg operator and the type I seesaw mechanism, with lepton doublets and right-handed neutrinos assumed to be triplets of $A_4$. Unlike previous analyses, we allow right-handed charged leptons to transform as all combinations of $\mathbf{1}$, $\mathbf{1}'$ and $\mathbf{1}…
The decay $H\to \ell^+\ell^- γ$, $\ell=e,μ$, receives contributions from $H\to Z[\to \ell^+\ell^-] γ$ and a non-resonant contribution, both of which are loop-induced. We describe how one can separate these sub-processes in a gauge-independent way, define the decay rate $Γ(H\to Zγ)$, and extract the latter from differential $H\to \ell^+\ell^- γ$ branching ratios. For $\ell=μ$ also the tree decay rate, which is driven by the muon Yukawa coupling, is important. We propose kinematic cuts optimized to separate the three contributions, paving the way to the milestones (i) discovery of $H\to Z γ$, (i…
Three-loop helicity amplitudes of four-lepton scattering in QED
Higgs Centre for Theoretical Physics, School of Physics and Astronomy The University of Edinburgh（爱丁堡大学物理与天文学学院希格斯理论物理中心）；Department of Mathematical Sciences, University of Liverpool（利物浦大学数学科学系）；Dipartimento di Fisica e Astronomia, Universita di Padova（帕多瓦大学物理与天文系）；INFN, Sezione di Padova（意大利国家核物理研究所帕多瓦分部）
Complete one-loop QED corrections to $D_s^+$ leptonic decays and impact on the CKM unitarity test
Chiba University（千叶大学）；Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University（名古屋大学小林-益川粒子宇宙起源研究所）；The University of Tokyo（东京大学）
The lepton sector is studied within a flavored non-renormalizable model where the $\mathbf{S}_{3}\otimes \mathbf{Z}_{2}$ flavor symmetry drives the Yukawa couplings. In this framework, the effective neutrino mass, that comes from the type II see-saw mechanism, as well as the charged lepton mass matrices are hierarchical and possessed (under a benchmark in the charged sector) a kind of Fritzsch textures that achieve to accommodate the mixing angles in good agreement with the last experimental data. The model predicts a CP-violating phase consistent with the experimental data and the branching r…
Probing axion-like particle couplings to leptons via the $γγjj$ signal at the FCC-ee
Department of Physics, Liaoning Normal University（辽宁师范大学物理学院）；Center for Theoretical and Experimental High Energy Physics, Liaoning Normal University（辽宁师范大学理论与实验高能物理中心）
Studies of strong field particle physics processes in electron/laser interactions and lepton collider interaction points are reviewed. These processes are defined by the high intensity of the electromagnetic fields involved and the need to take them into account as fully as possible. The main theoretical framework considered is the Furry picture. In this framework, the influence of a background electromagnetic field in the Lagrangian is calculated non perturbatively, involving exact solutions for quantised charged particles in the background field. These "dressed" particles go on to interact p…
