Related papers: Quark mass effects in B -> Xs gamma
We demonstrate that Borel QCD sum rules for heavy-light currents entail a very strong correlation between the $b$-quark mass $m_b$ and the $B$-meson decay constant $f_B,$ that is, $\delta f_B/f_B\approx-8\delta m_b/m_b.$ By starting from…
Theoretical predictions for the branching ratios of the $B \rightarrow X_s\,\gamma$ and $B \rightarrow K^*\,\gamma$ decays are calculated in the Standard Model and in the (type II) two-Higgs-doublet model. Both the complete leading and the…
We consider two-loop QCD corrections to the element $\Gamma_{12}^q$ of the decay matrix in $B_q-\bar{B}_q$ mixing, $q=d,s$, in the leading power of the Heavy Quark Expansion. The calculated contributions involve one current-current and one…
In the minimal supersymmetric model (MSSM), the upper limit of the lightest Higgs boson mass, $\mhl$, depends strongly on the top quark mass, $m_t$. We have computed the dominant two-loop radiative corrections to this upper limit of $\mhl$…
We give a summary about the various contributions which have to be calculated in order to obtain the next-to-leading logarithmic result for the branching ratio $BR(B \to X_s \gamma)$. Combining all these ingredients, which were obtained by…
We present a determination of the b-quark mass accurate through O(\alpha_s^2) in perturbation theory and including partial contributions at O(\alpha_s^3). Nonperturbative input comes from the calculation of the Upsilon and B_s energies in…
We use the threshold expansion and non-relativistic effective theory to determine the bottom quark mass from moments of the $b\bar{b}$ production cross section at next-to-next-to-leading order in the (resummed) perturbative expansion, and…
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…
We consider top-quark mass effects in the Higgs-interference contribution to $Z$-boson pair production in gluon fusion. While this production mechanism is formally of next-to-next-to leading order, its contribution is numerically important…
In this paper we investigate the next-to-leading power contribution to the $B_s \to \gamma\gamma$ and $B_s \to \gamma\ell\bar{\ell}$ decays from the strange quark mass effect with the dispersion approach which is QCD inspired and more…
We present the first lattice QCD calculation of the charm quark contribution to the nucleon electromagnetic form factors $G^c_{E,M}(Q^2)$ in the momentum transfer range $0\leq Q^2 \leq 1.4$ $\rm GeV^2$. The quark mass dependence, finite…
The impact of recent multi-loop calculations on precise determinations of charm- and bottom-quark masses and the strong coupling constant is discussed.
The integrated branching fraction of the process $B\to X_s l^+l^-$ is dominated by resonance background from narrow charmonium states, such as $B\to X_s\psi\to X_s l^+l^-$, which exceeds the non-resonant charm-loop contribution by two…
In this work the charm and bottom quark masses are determined from QCD moment sum rules for the charmonium and upsilon systems. In our analysis we include both the results from non-relativistic QCD and perturbation theory at…
We present $O(\alpha_s^2)$ QCD corrections to the fully-differential decay rate of a $b$-quark into inclusive semileptonic charmless final states. Our calculation provides genuine two-loop QCD corrections, beyond the…
We compute the two-loop term in the perturbation series for the quark-mass in the lattice Heavy Quark Effective Theory. This is an ingredient in the matching factor required to obtain the $b$-quark mass from lattice simulations of the HQET.…
We compute perturbative QCD corrections to the lifetime splitting between the charged and neutral $B$ meson in the framework of the heavy quark expansion. These next-to-leading logarithmic corrections are necessary for a meaningful use of…
We study the decay of the lightest neutral Higgs boson to a charm quark pair at full one-loop level in the MSSM with non-minimal quark flavour violation (QFV). In the numerical analysis we consider mixing between the second and the third…
We use lattice QCD simulations, with MILC gluon configurations and HISQ c-quark propagators, to make very precise determinations of moments of charm-quark pseudoscalar, vector and axial-vector correlators. These moments are combined with…
I will describe recent results from the HPQCD collaboration using a new very accurate method for charm quarks in lattice QCD, that we have used in calculations including the full effect of u, d and s sea quarks. Multiple values of the…