
Fundamental Interactions of Fields and Particles
Belarus, Bulgaria, Canada, Chile, China, Croatia, Finland, France, Germany, Greece, Hungary, India, Iran, Italy, Poland, Portugal, Russia, Serbia, Slovakia, Spain, United Kingdom, USA, Vietnam. The problem under study and the main purpose of the research:
The
main current problems of the modern theory of fundamental
interactions are the development of methods of quantum field theory,
their application to the description of elementary particle physics
within the Standard Model and beyond, theoretical support for
existing and planned experiments. Within the framework of the
Standard Model, efforts will be focused on the development of
multiloop computing methods and their applications to processes at
the Large Hadron Collider, the development of new approaches to
hadron physics, including heavy quark physics. In physics beyond the
Standard Model, the search for Dark matter, manifestations of
supersymmetry and other possible new physical phenomena are of
particular interest. Theoretical support for the search for new
physics in accelerator experiments will be combined with research and
analysis of astrophysical data.
Brief annotation and scientific rationale: Quantum Field Theory (QFT) is a widely recognized “language” used to describe the properties of elementary particles and their interactions. It is well known that the triumph of the Standard Model (SM) of particle physics would have been impossible without comparing experimental data obtained from accelerators such as LEP (CERN), HERA (DESY), Tevatron (Fermilab), and LHC (CERN) with highprecision calculations performed using QFT methods. Many years have passed since the construction of the SM, and all these years scientists were searching for New Physics. The problem of dark matter in the Universe is an obvious argument for such searches. The main aim of the Project is to develop the quantum field formalism of gauge and supersymmetric theories, as well as to construct and study particle physics models beyond the Standard Model. In the context of the Project, it is planned to use existing experience and new ideas to investigate a wide range of problems related to highprecision calculations within and beyond perturbation theory as well as to the nature of possible New Physics. Special attention will also be paid to issues that arise at the intersection of particle physics, astrophysics, and cosmology.
Investigation of the shapes of higher twist contributions in deep inelastic scattering with the resummation of large threshold logarithms. Calculation of twoloop diagrams that arise in nonrelativistic QED using the effective mass method and investigation of the completeness of basis functions for elliptic polylogarithms. Development of a new specialized computer package for the epsilon expansion of generalized hypergeometric functions with one or more variables, whose indices depend on the dimensional regularization parameter, as well as for the numerical calculation of the resulting functions. Explicit analytical calculation of multipoint master integrals using differential equations. Calculation of twoloop contributions to electronmuon scattering and quarkonia production. Calculation of the double spectral density in the problem of sum rules for BantiB mixing, which is an important experimental quantity that imposes strict constraints on possible new physics. Calculation of threeloop massive form factors and polarization operators in QCD. Calculation of multiloop amplitudes and form factors with a large number of kinematic invariants in theories with extended supersymmetry. Derivation of systematic solutions to quantum spectral curve equations in the case of maximally supersymmetric YangMills theory in four dimensions and ABJM theory in three dimensions, both in the weak and strong coupling limits. Calculation of spectra, correlation functions, and amplitudes in a number of sixdimensional “fishnet” models. Application of the large charge expansion method to gauge theories and analysis of the resulting implications in both particle physics and condensed matter theory. Investigation of the scheme dependence of a previously proposed selfconsistent subtraction procedure for nonrenormalizable theories. Calculation of effective potentials for a range of theories of modified gravity and their application to analyze various inflationary models. Investigation of the theory and phenomenology of scalar and vector bosonic stars. Detailed cosmological and astrophysical analysis of the properties of primary black holes and their connection to the dark matter problem and observable supermassive black holes. Analysis of the prospects for experimental detection of additional Abelian gauge symmetries and an extended Higgs sector in a range of new physics models. Investigation of the socalled supersymmetric extensions of the Standard Model.
Physical
analysis of LHC data aimed at detecting manifestations of the “dark
sector” in events where either a Higgs boson or a Development of new (using neural networks for global scanning) as well as optimization and improvement of existing software for modeling physical processes beyond the Standard Model. Expected results of the project in the current year: Development of an optimized computer package for the expansion of generalized hypergeometric functions of one or several variables, whose indices depend on a regularization parameter, in terms of either generalized polylogarithms or repeated integrals with algebraic kernels. Development of computer code for the numerical computation of generalized hypergeometric functions and Feynman integrals defined by a system of differential equations, with any desired accuracy; for the case of functions of multiple variables, acceleration of individual procedures using modular arithmetic methods is planned to be implemented. Comprehensive analysis of contributions to the anomalous magnetic moment of the muon resulting from the quark thresholds in the hadronic vacuum polarization. Multiloop analysis of the possibility of implementing the asymptotic safety scenario within a quantum field theory model with gauge, Yukawa, and scalar interactions. Analysis of connections between integrable conformal quantum field theories in different spacetime dimensions, as well as their dual models. Calculation of multipoint correlation functions in fishnet models in the largespin limit. Calculation of twoloop corrections to the 3point form factor of the energymomentum operator for N=4 super YangMills theory on the Coulomb branch. Development of a method for systematic solution of quantum spectral curve equations for N=4 SYM and ABJM theories at large values of the Lorentz spin of twist 1 and 2 operators in the weak coupling limit. Calculation of anomalous dimensions of operators with large quantum numbers in the Standard Model using nonperturbative methods; comparison with perturbative results. Calculation of various observables for rare decays involving leptons, assessing the possibility of detecting New Physics in these processes. Analysis of the Higgs boson production in events with large missing energy at the LHC within the framework of twoHiggs doublet extensions of the Standard Model with an additional hidden scalar sector. Investigation of the problem of forming massive galaxies and supermassive black holes in the centers of galaxies in the early Universe. Analytical derivation of a relation linking the observational properties of giant voids in the universe, which appear practically empty, with the density of matter at the center of the void and the initial parameters of the primordial perturbation from which it originated. Analysis of the bosonicstars stability, estimation of their lifetime. Calculation of the «slowroll» parameters in the framework of various models of inflation, taking into account the dynamic effects associated with the use of quantum effective potentials obtained by means of the generalized renormalization group; a study of the phenomenological consequences of these quantum effects.
Brief annotation and scientific rationale: Lacking a complete theoretical understanding of the color confinement, the only method of applying QCD is based on the factorization of the shortdistance (perturbative) and longdistance (nonperturbative) dynamics. The conventional systematic way of dealing with the longdistance part is to parametrize it in terms of matrix elements of quark and gluonoperators between hadronic states generating GPDs, DAs, TMDs, etc. These matrix elements have to be either extracted from experiment or determined on the lattice. In many phenomenological applications they are usually modeled in terms of various nonperturbative methods or models. The main objective of the project is to develop comprehensive theoretical frameworks to study the multidimensional partonic content of hadrons by combining various approaches based on the factorization theorem and starting from the first principles of QCD. For many years, theoretical and experimental studies of the nucleon structure have been restricted to a onedimensional picture along a lightcone direction. Within this one dimensional picture, quark and gluon contents of the nucleus are described by the parton distribution functions (PDFs) which depend on the longitiudinal momentum of the parton inside the hadron. The last decade has witnessed a tremendous effort to go beyond this onedimensional description of the nucleon. Recent improvements in experimental facilities such as increased electron beam luminosities and polarization degrees, detector resolution and coverage, and advanced theoretical computation frameworks, such as calculating radiative and power corrections to complementary sets of observables, provide a breakthrough for investigating the multidimensional partonic content of the nucleon, which is also referred to as hadron tomography. In this respect, the multidimensional parton distribution functions such as transversemomentumdependent distribution functions (TMDs) or generalized parton distribution functions (GPDs) have been the key subjects of both experimental and theoretical studies. With the advent of new generation colliders such as the Electron Ion Collider (EIC) in the USA and the Large Hadron electron Collider (LHeC) at CERN, theoretical improvements of these distribution functions are mandatory for a precise comparison with experimental data. Motivated from this need, the main objective of the proposed project is to develop a comprehensive theoretical framework to study the multidimensional partonic content of the hadrons by combining various approaches starting from the first principles of QCD. Expected results upon completion of the project: Analytic evaluation of 3loop 2point Feynman masterintegrals with composite external vertices for arbitrary indices of propagators. Calculation of α^{2}_{s}(α_{s}β_{0})^{n1} and α^{3}_{s}β_{1}(α_{s}β_{0})^{n2} contributions in the nonsinglet ERBL evolution kernel and correlator of two vector composite quark currents in QCD. Calculation of pion electromagnetic form factors in the framework of lightcone sum rules in the low and (or) moderate energy regime. Revision of distribution amplitudes (leading twist) of (pseudo)scalar and (longitudinal and transverse) vector mesons within QCD sum rules taking into account new QCD corrections O(α^{2}_{s}) obtained by us for all of their components. Derivation and analysis of the full differential equation system for Feynman integrals with multiple parameters of masses and impulses. Study of tau lepton decays and processes of electronpositron annihilation into mesons including the processes with three pseudoscalar mesons in the final state. Investigation of the inner structure and nature of the meson interaction at low energies by using the Nambu–JonaLasinio model. Study of the DrellYan hadronic structure function within the perturbative QCD in α^{2}_{s }order of the coupling constant. Сheck of the LamTung identity in α^{2}_{s} order of the strong coupling constant. Study of dark axion portal and obtaining bounds for the model in fixed target experiments. The analysis of new physics for NA64 experiment. Study of visible mode of axion or dark photon. Study of the sum rules for hadron fragmentation functions in QCD with the use of the generalized truncated Mellin moments approach. Investigation of analytical and numerical optimizations of perturbative series for observables using the renormalization group in QCD. Study of anomalous transport phenomena in a relativistic quantum medium associated with the curvature of spacetime. Study of the influence of the hadron potential at large distances on the total cross sections, which determines the peculiarity of the scattering amplitude at small momentum transfer. Investigation of the energy dependence and crossing properties of the new anomalous terms of the elastic amplitude of protonproton and protonantiproton scattering at NICA energies. Study of the newfound types of transverse momentum dependent parton distributions within the original frame that involves the newlyfound additional contribution in the inverse Radon transforms. Study of the phase diagram of the SU(2)Higgs Electroweak theory. Study of Z(N) symmetry and thermodynamic properties of metastable states at very high temperature in the context of QCD and Electroweak theory. The creation of a computational framework to analyze CMS Open Data.
Expected results of the project in the current year: Calculation of fourparticle decays of the tau lepton into meson states in the framework of the Nambu–JonaLasinio model in order to verify the model on new classes of processes. Research of the meson interactions at low energies by using phenomenological models for better understanding of the nonperturbative region of QCD. Study of integral representation of hypergeometric function of Horn type. Study of heavy meson leptoproduction in Generalized Parton Distributions approach. Study of the charge sum rules for hadron fragmentation functions in QCD. Study of inclusive hadron production in protonproton and heavyion collisions at the collider NICA kinematics. Analytical and numerical optimization of perturbative series for observables using the renormalization group in QCD. Applications to the DIS sum rules. Сalculation of the electromagnetic pion form factor for moderate momentum transfers in the framework of the analytical perturbation theory of QCD and сomparison with the latest JLab experimental data. Analytical and numerical optimizations of perturbation series are expected to be performed for observables using βexpansion and renormalization group in QCD. Improvement of estimates of: Rrelation, width of taudecay, and Bjorken polarized SR. The main asymptotics at small Bjorken x for the QCD kernels DGLAP, P(x), and ERBL, V(x,y), at any number of loops n. Investigation of the possibility of the existence of previously unknown phase transitions in a relativistic fluid of elementary particles in the region of ultralow temperatures and extremely high accelerations and vorticities. Derivation of estimates for the energy dependence of the contribution of the tenzor pomeron to the spindependent amplitudes of nuclonnuclon elastic scattering. Getting quantitative description of all available experimental data of the differential cross sections and spincorrellation parameters in elastic NNscattering from sqrt(s)= 5 GeV up to sqrt(s)= 14 TeV. The study of the contribution of effects induced by the effective oneloop action of HeisenbergEuler QED, as well as its generalization to QCD, to the transport coefficients of transport effects (CME, CSE, CESE, CMW, CEW, CVE) in heavy ion collisions. The study of particle productions with orbital angular moments in strong interactions at heavyion collisions Analysis of manifestation of dark matter axions in spin effects. Implementation of analytic evaluations of 3loop 2point Feynman masterintegrals with composite external vertices for arbitrary indices of propagators. Calculation of the correlator of two vector composite quark currents and the nonsinglet Efremov RadyushkinBrodskyLepage evolution kernel of the orders α^{2}_{s}(α_{s}β_{0})^{n1} and α^{3}_{s}β_{1}(α_{s}β_{0})^{n2} in QCD. Study of the Todd hadronic structure function of DrellYan processes taking into account quark polarization.
Brief annotation and scientific rationale: The project is expected to develop lowenergy effective field theories: nonrelativistic quantum electrodynamics (NRQED) and covariant quark model of hadrons (Covariant Confined Quark Model, CCQM). The Standard Model of particle physics, formulated about 50 years ago, forms the basis of our understanding of fundamental interactions. During this time, significant theoretical work has been carried out to improve the calculation technique and increase the accuracy of predictions in the SM. An effective field theory (EFT) is a quantum field theory which is not fundamental but is valid over a limited range of energies or distances. This makes it possible to successfully use EFT and renormalization group methods to calculate real physical quantities and processes observed in the experiment with high accuracy. The EFT approach provides not only a systematic approach to the analysis of experimental results, but is also a valuable tool for determining the correlation of various observables, which gives a deeper understanding of where to look for possible indicators of new physics beyond the SM. Expected results upon completion of the project: Exploration of the possibilities of using the combined approach in NRQED, when part of the contributions to the energy of the bound system is considered in the framework of QED, as the total sum over all terms in the powers of the electron binding parameter v/c~Zα.
Introduction of new terms in the general NRQED scheme, which will make it possible to take into account the contributions of light scattering on light, nontrivial centipede diagrams for one and twoloop selfenergy diagrams, necessary for calculating corrections of the order mα^{7}mα^{8 }and higher.
Within the framework of CCQM, investigate the possibility of violation of lepton universality in lepton decays of charmonium and bottomonium and their radial excitations. Obtain bounds on the values of the Wilson coefficients of the Standard Model Effective Theory (SMEFT) operators responsible for the violation of lepton universality in the tauon sector. Calculate the partial widths of strong and electromagnetic decays of vector Dmesons with an open charm. Calculate matrix elements and widths of nonleptonic twoparticle decays of charmed baryons without changing the charm. Perform an analysis of strong decays of the charmoniumlike state Y(4230) in order to study the nature of its structure. Perform a theoretical analysis of lepton decays of the Bmeson with four leptons in the final state. Expected results of the project in the current year:
Сalculation
of the transition energies in the antiprotonic helium (p^{−}−He^{+})
atom, taking into account corrections in
Calculation
of the fine and hyperfine structure parameters in the bound states of
molecular hydrogen ions H_{2}^{+} and
HD^{+} taking
into account all contributions up to the order of mα^{7}ln(α)
inclusive, which gives a relative accuracy of the frequency (energy)
Investigation of the possibility of violation of lepton universality in lepton decays of charmonium and bottomonium and their radial excitations within the framework of CCQM. Obtaining of bounds on the values of the Wilson coefficients of the Standard Model Effective Theory (SMEFT) operators responsible for the violation of lepton universality in the tauon sector. Calculation of the partial widths of strong and electromagnetic decays of vector Dmesons with an open charm.
Modern heavy ion accelerators make it possible to study the properties of strong interactions of elementary particles, which are described by quantum chromodynamics (QCD) under the influence of extreme external conditions. In particular, the quarkgluon matter that is created in such experiments is expected to have a temperature of several hundred MeV, the baryon chemical potential of about 100 MeV, external magnetic field eB ~ 1 GeV^{2} and relativistic rotation with an angular velocity of ~ 10 MeV. Such conditions significantly change the properties of QCD. In the presented project, it is planned to study the properties of QCD at nonzero baryon density, high temperature, large external magnetic field and relativistic rotation using lattice simulation and other approaches.
In
the presented project, it is planned to study the properties of QCD
at nonzero baryon density, nonzero temperature and It is expected that quarkgluon matter, which is produced in the process of collision of heavy ions, is not only highly heated and affected by a strong magnetic field but also has a nonzero angular velocity of rotation. Therefore, to interpret the results of heavy ion collision experiments, an important theoretical problem is the study of the properties of rotating quarkgluon matter. In the presented project, we are planning for the first time to study the properties of rotating quarkgluon matter in the framework of lattice simulation. One of the aims of the project is to impose new constraints on the equation of state of the nuclear and hadronic matter under extreme conditions existing in heavyion collisions and the centers of compact stars. For this, the description of strongly interacting systems in and out of equilibrium will be developed. Such observables as the strange and charmed particle production, the directed and elliptic flows of particles, the global spin polarization of hyperons and their intercorrelations will be analyzed within transport and hydrodynamic approaches and compared with existing and future experimental data. Various sources of the spin polarization such as local vorticity of the medium, axial vortex effect, and electromagnetic field will be quantitatively compared and their role in the formation of the observable polarization signal will be clarified. The possibility of the thermodynamic description of light nuclei and hypernuclei production in heavyion collisions within the hydrodynamic approach will be theoretically explored. Formulation of the equations of the viscous hydrodynamics with the internal spin and rotation degrees of freedom as an effective field theory will be achieved. Possible phase transformation in nonequilibrium and equilibrium nuclear matter under the influence of compression, heating, magnetic field, and rotation will be classified and studied. New constraints on the equation of state from the description of the neutron star masses, radii, and the neutron star cooling should be obtained. Elementary hadronic scattering amplitudes and the corresponding differential cross sections are important ingredients of transport models. The multichannel description of the mesonbaryon scattering within the generalized potential approach based on the chiral SU(3) Lagrangian with the parameters tuned to the lattice QCD data and available experimental data on the hadron scattering will be developed. Expected results of the project in the current year: The equation of state calculated within the relativistic meanfield model and the particle propagation under the influence of the corresponding meanfield potentials will be included in the PHSD model. The impact of the potentials on the particle flow and the spin polarization will be investigated. New experimental data and, particularly, the directed flow obtained by the STAR collaboration for goldgold collisions at the center of mass energy 3GeV will be analyzed within the hydrodynamic approach. Superfluidity and superconductivity of vector bosons in a rotating piece of nuclear matter and a strong magnetic field will be studied. The properties of soft meson modes will be studied in equilibrium and nonequilibrium nuclear systems. Charm meson scattering off pions will be analyzed within the effective chiral field theory. The method of calculation of triangle and box diagrams conserving power counting will be developed. The resulting amplitudes will be confronted with the Lattice QCD results. Study of various issues related to the influence of rotation on the properties of gluodynamics and QCD. In particular, it is planned to study the equation of state of a rotating QCD, the effect of rotation on the confinement/deconfinement phase transitions and the breaking/restoration of chiral symmetry, the effect of rotation on the interaction potential of static quarks, inhomogeneous phases of rotating quark matter, etc. Study of the simultaneous influence of the magnetic field and the baryon density on the QCD equation of state. In this case, lattice calculations will be carried out with the physical masses of dynamic u, d, squarks.
The Standard Model of particle physics is the most successful theory of fundamental interactions. Despite numerous experiments on its verification and a deep theoretical study of its properties, there are still many problems in this model that need to be solved. The presence of such problems leads us to believe that the Standard Model is only an effective theory, i.e., a lowenergy approximation of a more fundamental physical theory. To search for new physical phenomena, it is necessary to have highprecision predictions obtained within the framework of the Standard Model. Within this project, it is planned to obtain such predictions for the conditions of existing and future experiments at colliders, including LHC, FCCee, CEPC, ILC. Calculations will be carried out in order to carry out precise verification of the Standard Model (SM) and search for the limits of applicability of the latter.
Neutrinos are a unique source of information on physics beyond the Standard Model. In particular, reliably observed transitions between different types of neutrinos (neutrino flavors) indicate a violation of the conservation of the electron, muon and taon quantum numbers, which is present in the SM with massless neutrinos. The project is devoted to the study of physical processes involving neutrinos, including elementary exclusive interactions of neutrinos with nucleons and nuclei, neutrino transport in matter, taking into account coherent and inelastic interactions, study of astrophysical and cosmological effects, superhighenergy neutrinos in cosmic rays, manifestation of neutrino oscillations in primary nucleosynthesis under extreme astrophysical conditions (in particular, in the vicinity of astrophysical black holes), as well as in accelerator and reactor experiments. In particular, the hypothesis about the possible existence of a sterile neutrino, its role in nucleosynthesis and the formation of the largescale structure of the Universe will be considered. It is also planned to study a new mechanism for the production of ultrahighenergy neutrinos, up to 10^{21} eV (UHECR) in models of modified gravity in higherdimensional space. Research carried out within the framework of this project will allow obtaining restrictions on models of compact objects, on the properties of particles (for example, on the mass of a graviton), as well as on alternative theories of gravity, which have been proposed recently. In recent years, reliable evidence has been obtained for the association of highenergy neutrinos with blazars, which are most likely supermassive black holes, and the construction of consistent models of these phenomena is also extremely important and timely. Cosmological and astrophysical phenomena predicted in modified gravity models will be investigated. First of all, scalartensor models of gravity will be considered and the manifestations of quantum field effects in them will be studied.
Improvement of basic phenomenological models of electromagnetic nucleon formsfactors in the spacelike and timelike domains of q^{2 }based on the global statistical analysis of elastic electron scattering data on hydrogen and deuterium. Implementation of the models in the form of software modules of the GENIE neutrino generator. Application of the results to calculations of the cross sections of neutrinonucleon interactions in the models of the running axial mass (M_{A}^{run}) and SuSAM*. Improvement of the superscaling model SuSAM* with a modified scaling function based on a global statistical analysis of quasielastic electron scattering data on various nuclear targets (from hydrogen to uranium). Model implementation in the GENIE generator. Predictions of the momentum distribution of nucleons in the nucleus within the superscaling approach. Improvement of the RK model of resonance neutrinoproduction of pions with corrected contributions to the full amplitude based on the global statistical analysis of single pion production data in (anti)neutrino interactions with hydrogen and deuterium. Implementation of the model in the GENIE generator. Development of a method for solving the quantum kinetic equations describing the transport of massive highenergy neutrinos in heterogeneous (astrophysical) media taking into account the neutrino mixing (including mixing with hypothetical sterile states) and their coherent and inelastic interactions with matter. Application of the theory to the calculation of the passage through the Sun of neutrinos generated by cosmic rays in the solar atmosphere (prediction of the flavor composition, energy and angular distributions). Evaluation of the corresponding background in the experiments on the detection of neutrinos generated by the annihilation of dark matter particles gravitationally bound in the Sun. Study of the contribution of ultrahigh energy neutrinos arising in a multidimensional modification of gravity and comparison of theoretical expectations with observations with the Baikal GVD and IceCube detectors. Calculation of electroweak radiative corrections to electronpositron annihilation processes, which are planned to be studied at future colliders, including FCCee, CEPC and Super CharmTau Factory. Creation of computer programs that can be directly used to simulate and analyze data from experiments at these colliders. Application of the method of parton distributions developed in QCD to describe electrodynamic corrections to processes studied in current and future experiments in the field of high energy physics. Construction of highprecision theoretical predictions for Bhabha scattering processes at small and large angles used for luminosity monitoring at electronpositron colliders.
Analysis
of semileptonic manyparticle decay modes of tau leptons taking into
account the excited states of mesons in intermediate states.
Construction of a consistent scheme for describing such decays and
creation of a computer program for simulating such
processes. Study of a new mechanism for the production of highenergy cosmic rays due to the annihilation and decay of superheavy dark matter particles in the form of heavy leptons. Highenergy neutrinos arising in these processes can potentially be detected by the Baikal GVD and IceCube neutrino telescopes. Analysis of cosmological restrictions on the sterile neutrino properties at a large mixing angle with active neutrinos, in particular, the effects of a possible resonance. As part of the TAIGA experiment, search for joint events with ultrahighenergy neutrinos detected with the Baikal GVD and IceCube facilities.
A
twoloop implementation of the inverse seesaw mechanism with residual
discrete symmetry stabilizing dark matter.
Development
of an extension of the Standard Model with an axionlike particle
contributing to the neutrino mass and dark matter. Application of the method of parton distributions in QED to describe the processes of electronpositron annihilation, muon decay and electronmuon scattering under the conditions of current and future experiments. With its help, higherorder radiative corrections will be taken into account in the nexttoleading order logarithmic approximation. Analysis of semileptonic manyparticle decay modes of tau leptons taking into account the excited states of mesons in intermediate states. Construction of a consistent scheme for describing such decays in the framework of the NambuJonaLasinio model. Analysis of quantum field effects in scalartensor models of modified gravity, including the generation of cosmological inflation due to effective potentials and the study of instabilities in solutions for the scalar field. Description of the processes of electronpositron annihilation into Dmesons through intermediate states of excited charmonia for experiments at the BESIII accelerator and the future Super CharmTau Factory.
