The LHCb collaboration has recently performed a first measurement of the angular production asymmetry in the distribution of beauty quarks and anti-quarks at a hadron collider. We calculate the ...corresponding standard model prediction for this asymmetry at fixed-order in perturbation theory. Our results show good agreement with the data, which is provided differentially for three bins in the invariant mass of the \(b \bar b\) system. We also present similar predictions for both beauty-quark and charm-quark final states within the LHCb acceptance for a collision energy of \(\sqrt{s} = 13 \, {\rm TeV}\). We finally point out that a measurement of the ratio of the \(b \bar b\) and \(c \bar c\) cross sections may be useful for experimentally validating charm-tagging efficiencies.
We calculate a set of one-loop corrections to \(h\to b\bar b\) and \(h\to \tau\bar \tau\) decays in the dimension-6 Standard Model effective field theory (SMEFT). In particular, working in the limit ...of vanishing gauge couplings, we calculate directly in the broken phase of the theory all large logarithmic corrections and in addition the finite corrections in the large-\(m_t\) limit. Moreover, we give exact results for one-loop contributions from four-fermion operators. We obtain these corrections within an extension of the widely used on-shell renormalisation scheme appropriate for SMEFT calculations, and show explicitly how UV divergent bare amplitudes from a total of 21 different SMEFT operators are rendered finite within this scheme. As a by-product of the calculation, we also compute to one-loop order the logarithmically enhanced and finite large-\(m_t\) corrections to muon decay in the limit of vanishing gauge couplings, which is necessary to implement the \(G_F\) input parameter scheme within the SMEFT.
We calculate the \(\mathcal{O}(\alpha_s)\) QCD corrections to the inclusive \(h\to b\bar b\) decay rate in the dimension-6 Standard Model Effective Field Theory (SMEFT). The QCD corrections ...multiplying the dimension-6 Wilson coefficients which alter the \(hb\bar b\)-vertex at tree-level are proportional to the Standard Model (SM) ones, so next-to-leading order results can be obtained through a simple rescaling of the tree-level decay rate. On the other hand, contributions from the operators \(Q_{bG}\) and \(Q_{HG}\), which alter the \(gb\bar b\)-vertex and introduce a \(hgg\)-vertex respectively, enter at \(\mathcal{O}(\alpha_s)\) and induce sizeable corrections which are unrelated to the SM ones and cannot be anticipated through a renormalisation-group analysis. We present compact analytic results for these contributions, which we recommend to be included in future phenomenological studies.
We discuss two projects exploring the integration of thin CMOS pixel sensors in order to prototype ladders matching the geometry needed for the ILD vertex detector. The PLUME project has designed and ...fabricated full-size and fully functional double- sided layers which currently reach 0.6 % X0 and aim for 0.3 % X0 in mid-2012. Another approach, SERNWIETE, consists in wrapping the sensors in a polyimide-based micro-cable to obtain a supportless single-sided ladder with a material budget around 0.15 % X0. First promising samples have been produced and the full-size prototype is expected in spring 2012.
ISIS (In-situ Storage Imaging Sensor) is a novel CMOS sensor with multiple charge storage capability developed for the ILC vertex detector by the Linear Collider Flavour Identification (LCFI) ...collaboration. This paper reports test results for ISIS2, the second generation of ISIS sensors implemented in a 0.18 micron CMOS process. The local charge storage and charge transfer were unambiguously demonstrated.
