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Electromagnetic dipole moments of fermions
Full text linkThe electric (EDM) and magnetic (g-2) dipole moments are static properties sensitive to quantum corrections induced by the virtual particles that populate the vacuum.
Indeed, they are well suited to test the Standard Model of Elementary of particle physics and to unveil unknown New Physics (NP) hidden at high energy.
The electron and muon g-2 have been measured with the wonderful precision of 0.24 ppb and 0.54 ppm, respectively, and thus they represent one of the strongest confirmation of the SM and greatest achievement in Quantum Field Theory.
Nonetheless the SM deficiencies, the explanation of dark matter and dark energy, cosmological inflaton, neutrino oscillations and masses, the strong CP problem and the origin of matter-antimatter asymmetry, call for new physics beyond the SM.
Since NP contribution to the dipole moments of a fermion f is expected to be proportional to m_f^2, dipole moments of heavy fermions, such as the top quark or the tau lepton, are much more sensitive to NP effects than the electron or muon ones.
However the very short lifetime of these unstables particle makes it impossible to directly measure their electromagnetic properties.
Therefore, indirect information must be obtain by precisely measuring cross sections and decay rates in processes involving the emission of a real photon by the heavy fermion.
In this thesis, we investigate the possibility to measure the anomalous magnetic moment and the electric dipole moment of the top quark at the LHC and tau lepton at future high luminosity B-factories
Supplemental material for "NNLO QCD corrections to the q2 spectrum of inclusive semileptonic B-meson decays"
No full text<p>Supplementary material for the publication "NNLO QCD corrections to the q2 spectrum of inclusive semileptonic B-meson decays".</p>
<p>See the file <strong>README</strong> for instructions.</p>
Third order correction to semileptonic decay: fermionic contributions
Full text linkWe present the QCD corrections of order αs3 to the decay rate of b→uℓν¯ℓ, with ℓ=e, μ, originating from diagrams with closed fermion loops and neglecting the mass of the up quark. Our calculation relies on integration-by-parts reduction of Feynman integrals with one propagator raised to a symbolic power in kira and the numerical evaluation of master integrals with amflow. This allows us to obtain results for the fermionic contributions to the total semileptonic rate with an accuracy of more than 30 digits.We present the QCD corrections of order to the decay rate of , with , originating from diagrams with closed fermion loops and neglecting the mass of the up quark. Our calculation relies on integration-by-parts reduction of Feynman integrals with one propagator raised to a symbolic power in Kira and the numerical evaluation of master integrals with AMFlow. This allows us to obtain results for the fermionic contributions to the total semileptonic rate with an accuracy of more than thirty digits
Taming the N3LO corrections to semileptonic b -> u decay
No full textWe review the calculation of the QCD corrections of order α3s to the decay rate of b→ulν, originating from diagrams with closed fermion loops and neglecting the mass of the up quark. Our calculation takes advantage of integration-by-parts reduction of Feynman integrals with one propagator raised to a symbolic power in Kira. The five-loop master integrals are then evaluated numerically with the auxiliary mass flow method as implemented in AMFlow, in combination with an ad hoc interface to Kira. We obtain results for the fermionic contributions to the total semileptonic rate with an accuracy of more than thirty digits
Probing top quark electromagnetic dipole moments in single-top-plus-photon production
Full text linkThe production of a single top quark in association with an isolated photon probes the electromagnetic coupling structure of the top quark. We investigate the sensitivity of kine- matical distributions at the LHC in single-top-plus-photon production in view of a detection of anomalous electric and magnetic dipole moments of the top quark
NNLO QCD corrections to the q spectrum of inclusive semileptonic B-meson decays
Full text linkWe calculate the next-to-next-to-leading order QCD corrections to the leptonic invariant mass (q) spectrum of semileptonic b → c inclusive decays, taking into account the mass of the charm quark and the charged lepton in the final state. We obtain analytic results in terms of generalized polylogarithms and present numerical studies of the () corrections to the q spectrum of b → decays, for ℓ = e, μ and τ, in the kinetic scheme. Our computation can be used to incorporate the recent measurements of q moments by Belle and Belle II into global fits of inclusive semileptonic B-decays.We calculate the next-to-next-to-leading order QCD corrections to the leptonic invariant mass () spectrum of semileptonic inclusive decays, taking into account the mass of the charm quark and the charged lepton in the final state. We obtain analytic results in terms of generalized polylogarithms and present numerical studies of the corrections to the spectrum of decays, for and , in the kinetic scheme. Our computation can be used to incorporate the recent measurements of moments by Belle and Belle II into global fits of inclusive semileptonic -decays
Kolya: an open-source package for inclusive semileptonic decays
Full text linkWe introduce the code kolya, an open-source tool for phenomenological analyses of inclusive semileptonic decays. It contains a library to compute predictions for the total rate and various kinematic moments within the framework of the heavy quark expansion, utilizing the so-called kinetic scheme. The library currently includes power corrections up to . All available QCD perturbative corrections are implemented via interpolation grids for fast numerical evaluation. We also include effects from new physics parameterized as Wilson coefficients of dimension-six operators in the weak effective theory below the electroweak scale. The library is interfaced to CRunDec for easy evaluation of the quark masses and strong coupling constant at different renormalization scales. The library is developed in Python and does not require compilation. The code is flexible and can be extended to other kinds of inclusive decays such as meson lifetimes, and meson decays.We introduce the code kolya, an open-source tool for phenomenological analyses of inclusive semileptonic meson decays. It contains a library to compute predictions for the total rate and various kinematic moments within the framework of the heavy quark expansion, utilizing the so-called kinetic scheme. The library currently includes power corrections up to . All available QCD perturbative corrections are implemented via interpolation grids for fast numerical evaluation. We also include effects from new physics parameterised as Wilson coefficients of dimension-six operators in the weak effective theory below the electroweak scale. The library is interfaced to CRunDec for easy evaluation of the quark masses and strong coupling constant at different renormalization scales. The library is developed in Python and does not require compilation. It can be used in an interactive Jupyter notebook session
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