Related papers: Perturbative relations between $e^+e^-$ annihilati…
An updated measurement of alpha_s(m_tau) from ALEPH tau hadronic spectral functions is presented. We report a study of the perturbative prediction(s) showing that the fixed-order perturbation theory manifests convergence or principle…
We compute non-perturbative contributions to the Adler function, the derivative of the vacuum polarization function in gauge theory, using resurgence methods and Borel-summed gauge field propagators. At 2-loop, to order $1/N_f$, we…
We apply the method of graphical functions that was recently extended to six dimensions for scalar theories, to $\phi^3$ theory and compute the $\beta$ function, the wave function anomalous dimension as well as the mass anomalous dimension…
The first complete calculation of the quadratic quark mass correction to the correlator of the two currents relevant for the strangeness-changing semihadronic tau-decay rate is presented including its real part at the four-loop level. This…
Recently, the Belle collaboration reported the first measurements of the $\tau^- \to\nu_{\tau}\pi^-e^+e^-$ branching fraction and the spectrum of the pion-dielectron system. In an analysis previous to Belle's results, we evaluated this…
We have calculated the perturbative corrections to all the structure functions in the semileptonic decays of a heavy quark. Assuming an arbitrary gluon mass as a technical tool allowed to obtain in parallel all the BLM corrections. We…
We compute a variational approximation to the entanglement entropy for states of the Gross-Neveu model. Further, we examine the functional dependence of the entanglement entropy on the coupling and number of colors in the theory. Our…
We present predictions for the $e^{+}e^{-}$ event shape angularities at NNLL$^{\prime}$ resummed and $\mathcal{O}(\alpha_s^{2})$ matched accuracy and compare them to LEP data at center-of-mass energies $Q=91.2$ GeV and $Q=197$ GeV. We…
We reconsider the issue of the search for a nonzero electric dipole form factor (EDM) $d_\tau(s)$ using optimal observables in $\tau^+\tau^-$ production by $e^+ e^-$ collisions in the center-of-mass energy range from the $\tau$-pair…
An overview is given of Chiral Perturbation Theory and various applications to eta decays. In particular, the main decay $\eta\to3\pi$ is discussed at the one-loop level, and estimates of the higher order corrections are given. The…
A simple example of a non-equilibrium system for which fluctuations are important is a system of particles which diffuse and may annihilate in pairs on contact. The renormalization group can be used to calculate the time dependence of the…
The double lepton pair decay modes of the K_L meson are analyzed including all contributions of order p^6 in Chiral Perturbation Theory. The experimentally established e^+ e^- e^+ e^- mode and the recently observed e^+ e^- mu^+ mu^- mode…
The field theoretic renormalization group is applied to the stochastic Navier--Stokes equation that describes fully developed fluid turbulence. The complete two-loop calculation of the renormalization constant, the $\beta$ function, the…
Using a data sample of $(10087 \pm 44) \times {10^{6}}$ $J/{\psi}$ events collected with the BESIII detector, we search for the decays $\eta/\eta'\to e^+e^-\mu^+\mu^-$ and $\eta' \to \mu^+\mu^-\mu^+\mu^-$ via the radiative decays…
I briefly review three topics of recent interest concerning power corrections, renormalons and Sudakov resummation: (a) $1/Q$ corrections to event shape observables in $e^+ e^-$ annihilation, (b) power corrections in Drell-Yan production…
The paper is devoted to application of recently devised ghost-free Analytic Perturbation Theory (APT) for analysis of some QCD observables. We start with the discussion of the main problem of the perturbative QCD -- ghost singularities and…
The time evolution of entanglement tracks how information propagates in interacting quantum systems. We study entanglement entropy in CFT$_2$ with a time-dependent Hamiltonian. We perturb by operators with time-dependent source functions…
The question of the renormalization scheme dependence of the $\tau$ semileptonic decay rate is revisited in response to a recent criticism. Particular attention is payed to a distinction between a consistent quantitative description of this…
Physically relevant field-theoretic quantities are usually derived from perturbation techniques. These quantities are solved in the form of an asymptotic series in powers of small perturbation parameters related to the physical system, and…
We extend previous calculations of polarization observables for the annihilation reaction $\bar p +p\to \ell^{-}+\ell^{+}$ to the case of heavy leptons, such as the $\tau$-lepton. We consider the case when the beam and/or the target are…