Motivation for the mini-workshop on multiloop/multiscale methods and techniques in the context of precise Z-boson studies


The future 100-km circular collider (FCC, see the web page) will deliver the highest integrated luminosities to study all heavy Standard Model particles with unprecedented precision.

The first step of this collider (FCC-ee) will deliver e+e− collisions to study the Z, W, and Higgs bosons, and the top quark, but also the b and c quarks, and the tau lepton. The number of Z bosons produced by FCC-ee (up to 5×10^12), for example, is expected to be almost six orders of magnitude larger than the number of Z bosons collected at LEP (2×10^7), and orders of magnitude larger than that envisioned with a linear collider (a few 10^9). Furthermore, the exquisite determination of the centre-of-mass energy by resonant depolarization available in the storage rings will allow measurements of the W and Z masses and widths with a precision of a few hundred keV. The high-precision measurements and the observation of rare processes made possible by these large data samples will open opportunities for new physics discoveries, from very weakly-coupled light particles that could explain the yet unobserved dark matter to quantum effects of high-mass scale new physics typically up to 100 TeV. For these quantum effects to be measurable, however, the precision of the theoretical calculations that predict the various observables within the standard model and beyond will have to match that of the experimental measurements, i.e., to improve by one-to-two orders of magnitude with respect to current achievements. This tour-de-force will require complete two- and three-loop corrections to be calculated, and probably the developments of breakthrough computation techniques to keep the time needed for these numerical calculations within reasonable limits.

The purpose of the mini-workshop is to discuss:

(i) the precision of the theoretical calculations that predict the various observables within the standard model (and beyond) required to match that of the experimental measurements to be made by the FCC-ee,

(ii) the techniques to be applied and/or developed to reach this precision.

The programme will include detailed presentations on multiloop/multiscale techniques and other methods, identified bottle-necks problems of both present software and analytical/numerical methods, and discussions towards establishing a work plan for future studies.

For general physics studies connected with FCC-ee, you may consider to participate in the 2nd FCC Physcs weeks which will take place at CERN just a week after this event, 15-19 January 2018, see indico.

Registration for this event is currently open.
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