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The decay B_s -> mu^+ mu^- in the Standard Model is generated by the well-known W-box and Z-penguin diagrams that give rise to an effective quark-lepton operator Q_A at low energies. We compute QCD corrections of order alpha_s^2 to its…

High Energy Physics - Phenomenology · Physics 2014-03-18 Thomas Hermann , Mikolaj Misiak , Matthias Steinhauser

We consider Quantum Chromodynamics with external vector, axial-vector, scalar and pseudo-scalar currents and compute three-loop corrections to the corresponding vertex function taking into account massive quarks. We consider all non-singlet…

High Energy Physics - Phenomenology · Physics 2022-09-14 Matteo Fael , Fabian Lange , Kay Schönwald , Matthias Steinhauser

We present the two-loop corrected operator matrix elements contributing to the scale evolution of the longitudinal spin structure function $g_1(x,Q^2)$ calculated up to finite terms which survive in the limit $\epsilon = N - 4 \to 0$. These…

High Energy Physics - Phenomenology · Physics 2009-10-31 Y. Matiounine , J. Smith , W. L. van Neerven

We consider the currents formed by a heavy and a light quark within Quantum Chromodynamics and compute the matching to Heavy Quark Effective Theory to three-loop accuracy. As an application we obtain the third-order perturbative corrections…

High Energy Physics - Phenomenology · Physics 2010-04-30 S. Bekavac , A. G. Grozin , P. Marquard , J. H. Piclum , D. Seidel , M. Steinhauser

We perform extensive three-loop tests of the hexagon bootstrap approach for structure constants in planar $\mathcal{N}=4$ SYM theory. We focus on correlators involving two BPS operators and one non-BPS operator in the so-called $SL(2)$…

High Energy Physics - Theory · Physics 2015-10-07 Benjamin Basso , Vasco Goncalves , Shota Komatsu , Pedro Vieira

The measurements of the $\gamma\gamma$ and $b \bar b$ partial decay widths of an intermediate-mass Standard Model Higgs boson are among the most important goals of a future photon linear collider. While in an initially polarized $J_z=0$…

High Energy Physics - Phenomenology · Physics 2011-01-25 Michael Melles , W. James Stirling

Current status of the NNLO QCD corrections to B -> X_s gamma is reviewed. The calculations include three-loop matching conditions, four-loop anomalous dimensions as well as two- and three-loop on-shell amplitudes. Certain parts of the…

High Energy Physics - Phenomenology · Physics 2007-05-23 M. Misiak

We evaluate the corrections to the matching coefficient of the vector current between Quantum Chromodynamics (QCD) and Non-Relativistic QCD (NRQCD) to three-loop order containing a closed heavy-fermion loop. The result constitutes a…

High Energy Physics - Phenomenology · Physics 2009-07-24 P. Marquard , J. H. Piclum , D. Seidel , M. Steinhauser

We calculate the $O(\a_s)$ virtual corrections to the matrix element for $b \to s \gamma$, taking into account the contributions of the four-Fermi operator $O_2$ and the electromagnetic and color dipole-type operators. The results are…

High Energy Physics - Phenomenology · Physics 2011-01-05 C. Greub , T. Hurth , D. Wyler

We calculate the coefficients of operators with dimensions d <= 7 in the operator product expansion of correlators of q Gamma Q currents, for the effective field theory of an infinite-mass quark, Q. Exact two-loop results are obtained, with…

High Energy Physics - Phenomenology · Physics 2010-11-01 D. J. Broadhurst , A. G. Grozin

The most recent recalculation of the two-loop correction to the static quark-antiquark potential gave the numerical value different from the previously known one. We comment on the effect this change produces on the numerical estimates of…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. A. Penin , A. A. Pivovarov

We calculate the three-loop master integrals of Ref. [1] [arXiv:1709.02160] in analytic form. This allows us to present the fermionic contributions to the $\Delta B=2$ Wilson coefficients of the $B$-$\bar B$ decay matrix in…

High Energy Physics - Phenomenology · Physics 2022-07-06 Artyom Hovhannisyan , Ulrich Nierste

We report on recent results on the two-mass corrections for massive operator matrix elements at 2- and 3-loop orders in QCD. These corrections form the building blocks of the variable flavor number scheme. Due to the similar values of the…

High Energy Physics - Phenomenology · Physics 2018-07-23 J. Ablinger , J. Blümlein , A. De Freitas , A. Goedicke , C. Schneider , K. Schönwald

The 3-loop heavy flavor corrections to deep-inelastic scattering are essential for consistent next-to-next-to-leading order QCD analyses. We report on the present status of the calculation of these corrections at large virtualities $Q^2$.…

High Energy Physics - Phenomenology · Physics 2014-11-21 J. Blümlein , A. De Freitas , C. Schneider

We compute the matching coefficients between QCD and non-relativistic QCD for external vector, axial-vector, scalar and pseudo-scalar currents up to three-loop order. We concentrate on the non-singlet contributions and present precise…

High Energy Physics - Phenomenology · Physics 2022-06-22 Manuel Egner , Matteo Fael , Fabian Lange , Kay Schönwald , Matthias Steinhauser

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

Recent results on the calculation of 3-loop massive operator matrix elements in case of one and two heavy quark masses are reported. They concern the $O(n_f T_F^2 C_{F,A})$ and $O(T_F^2 C_{F,A})$ gluonic corrections, two-mass quarkonic…

High Energy Physics - Phenomenology · Physics 2016-08-14 J. Ablinger , J. Blümlein , A. De Freitas , A. Hasselhuhn , S. Klein , C. Raab , M. Round , C. Schneider , F. Wißbrock

We compute the three-loop QCD corrections to the massive quark form factors with external vector, axial-vector, scalar and pseudo-scalar currents. All corrections with closed loops of massless fermions are included. The non-fermionic part…

High Energy Physics - Phenomenology · Physics 2018-07-04 Roman N. Lee , Alexander V. Smirnov , Vladimir A. Smirnov , Matthias Steinhauser

We compute three-loop corrections to the singlet form factors for massive quarks using a semi-analytic method which provides precise results over the whole kinematic range. Particular emphasis is put on the anomaly contribution originating…

High Energy Physics - Phenomenology · Physics 2023-05-24 Matteo Fael , Fabian Lange , Kay Schönwald , Matthias Steinhauser

In this paper we present the complete two-loop vertex corrections to scalar and pseudo-scalar Higgs boson production for general colour factors for the gauge group ${\rm SU(N)}$ in the limit where the top quark mass gets infinite. We derive…

High Energy Physics - Phenomenology · Physics 2010-04-05 V. Ravindran , J. Smith , W. L. van Neerven