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Scenarios for electroweak baryogenesis require an understanding of the effective potential at finite temperature near a first-order electroweak phase transition. Working in Landau gauge, we present a calculation of the dominant two-loop…

High Energy Physics - Phenomenology · Physics 2014-11-17 Peter Arnold , Olivier Espinosa

The coefficient functions of the gluon condensate $<G^2>$, in the correlators of heavy-quark vector, axial, scalar and pseudoscalar currents, are obtained analytically, to two loops, for all values of $z=q^2/4m^2$. In the limiting cases…

High Energy Physics - Phenomenology · Physics 2010-11-01 D. J. Broadhurst , P. A. Baikov , V. A. Ilyin , J. Fleischer , O. V. Tarasov , V. A. Smirnov

We provide a compendium of techniques that can be used to compute $O(N_f\alpha^2)$ corrections to low-energy electroweak processes. Specifically, these are the 2-loop electroweak corrections containing a light fermion loop. It is shown that…

High Energy Physics - Phenomenology · Physics 2007-05-23 R. Akhoury , Paresh Malde , Robin G. Stuart

We discuss the renormalization of the electric charge at the two-loop level in the Standard Model of the electroweak interactions. We explicitly calculate the expression of the complete on-shell two-loop counterterm using the Background…

High Energy Physics - Phenomenology · Physics 2009-11-10 Giuseppe Degrassi , Alessandro Vicini

Two-loop electroweak corrections to the muon anomalous magnetic moment are automatically calculated by using GRACE-FORM system, as a trial to extend our system for two-loop calculation. We adopt the non-linear gauge (NLG) to check the…

High Energy Physics - Phenomenology · Physics 2018-10-31 Tadashi Ishikawa , Nobuya Nakazawa , Yoshiaki Yasui

Measurements of electroweak precision observables at future electron-positron colliders, such as the CEPC, FCC-ee, and ILC, will be sensitive to physics at multi-TeV scales. To achieve this sensitivity, precise predictions for the Standard…

High Energy Physics - Phenomenology · Physics 2021-04-07 Lisong Chen , Ayres Freitas

We evaluate the two-loop ${\cal O}(\alpha_sG_Fm_t^2)$ correction to the $ZZH$ coupling in the Standard Model by means of a low-energy theorem, assuming that the top quark is much heavier than the Higgs boson. We then construct a…

High Energy Physics - Phenomenology · Physics 2016-09-01 Bernd A. Kniehl , Michael Spira

First results on the radiative corrections of order O(N_f\alpha_s\alpha) are presented for the off-shell production of W or Z bosons at the LHC, where N_f is the number of fermion flavours. These corrections comprise all diagrams at…

High Energy Physics - Phenomenology · Physics 2021-02-03 Stefan Dittmaier , Timo Schmidt , Jan Schwarz

We compute the two-loop QCD corrections to $q g \to H q$ and $q \bar{q} \to H g$ amplitudes mediated by loops of nearly massless quarks. These amplitudes provide the last missing ingredient required to compute the NLO QCD corrections to the…

High Energy Physics - Phenomenology · Physics 2017-03-22 Kirill Melnikov , Lorenzo Tancredi , Christopher Wever

We present the dominant two-loop ${\rm O}\left(G_F^2M_H^4\right)$ electroweak corrections to the fermi\-onic decay widths of a high-mass Higgs boson in the Standard Model. The corrections are negative and quite significant, and are larger…

High Energy Physics - Phenomenology · Physics 2009-09-25 Loyal Durand , Bernd Kniehl , Kurt Riesselmann

The vacuum polarization functions $\Pi(q^2)$ of charged and neutral gauge bosons which arise from top and bottom quark loops lead to important shifts in relations between electroweak parameters which can be measured with ever-increasing…

High Energy Physics - Phenomenology · Physics 2009-10-28 K. G. Chetyrkin , J. H. Kuehn , M. Steinhauser

We calculate the two--loop electroweak corrections to the fermionic decay width of the Higgs boson at leading order in $m_{H}$. The sum of one--loop and two--loop radiative corrections turns out to be at 6% level over the whole range of…

High Energy Physics - Phenomenology · Physics 2009-10-28 Adrian Ghinculov

The momentum dependent two-loop contributions of the order $\mathcal{O}$($\alpha_s \alpha_t$) to the masses in the Higgs-boson sector of the MSSM are computed. Adopting the Feynman-diagrammatic approach and using a mixed…

High Energy Physics - Phenomenology · Physics 2014-10-03 S. Borowka

An analysis of electroweak corrections to the anomalous dipole moments of lepton from some special two-loop diagrams where a closed neutralino/chargino loop is inserted into relevant one-loop diagrams of the standard model is presented in…

High Energy Physics - Phenomenology · Physics 2008-11-26 Tai-Fu Feng , Lin Sun , Xiu-Yi Yang

We present the first calculation of the two-loop electroweak fermionic correction to the flavour-dependent effective weak-mixing angle for bottom quarks, sin^2 theta_{eff}^{b anti-b}. For the evaluation of the missing two-loop vertex…

High Energy Physics - Phenomenology · Physics 2010-04-21 M. Awramik , M. Czakon , A. Freitas , B. A. Kniehl

Perturbative corrections to b->c transitions at zero recoil are considered in the two-step matching scheme. The matching coefficient for the b->c currents from the intermediate effective theory (between the scales m_b and m_c) to the…

High Energy Physics - Phenomenology · Physics 2007-05-23 Andrey Grozin

A new framework to study electroweak physics at one-loop level in general ${\rm SU(2)_L \times U(1)_Y}$ theories is introduced. It separates the 1-loop corrections into two pieces: process specific ones from vertex and box contributions and…

High Energy Physics - Phenomenology · Physics 2008-02-03 K. Hagiwara , S. Matsumoto , C. S. Kim

The Higgs-mass dependence of the two-loop contributions to muon decay is analyzed at the two-loop level. Exact results are given for the Higgs-dependent two-loop corrections associated with the fermions, i.e. no expansion in the top-quark…

High Energy Physics - Phenomenology · Physics 2007-05-23 G. Weiglein

We provide high-precision predictions for muon-pair and tau-pair productions in a photon-photon collision by considering a complete set of one-loop-level scattering amplitudes, i.e., electroweak (EW) corrections together with soft and hard…

High Energy Physics - Phenomenology · Physics 2021-06-10 Mehmet Demirci , M. Fauzi Mustamin

The rare K -> pi nu anti-nu decays play a central role in testing the Standard Model and its extensions. Upcoming experiments plan to measure the decay rates with high accuracy. Yet, unknown higher-order electroweak corrections result in a…

High Energy Physics - Phenomenology · Physics 2011-03-02 Joachim Brod , Martin Gorbahn , Emmanuel Stamou