Resummation4PS · Advances in higher-order resummation and Parton Shower
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2017-10-01 → 2019-09-30
- EU contribution
- €175,420
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
Advances in higher-order resummation and Parton Shower
For the decades to come, the LHC will continue its exploration of the energy frontier by addressing several open questions in particle physics, notably the study of the fine details of the Higgs sector, and the search for small deviations from the SM which would ultimately diagnose the presence of new physics. Besides the great complexity of the measurements, this program requires an unprecedented level of precision in the theoretical predictions of the SM, and specifically of Quantum Chromodynamics (QCD). In the perturbative approach to QCD at colliders, the hard scattering is predicted by means of a power series in the strong coupling constant, that is truncated at a fixed order once the goal precision is achieved. However, a substantial part of the information about what happened in any given high-energy LHC collision is contained in the low-energy particles that are observed in the detector. The description of the multiscale evolution of the system from the energy of the hard scattering towards the low energies of the observed hadrons crucially requires the summation of all orders of the perturbative series in the soft and collinear limits, where the emission probability is enhanced. Improving this understanding is of paramount importance to derive the accurate predictions necessary for the success of the LHC mission. The objective of this proposal has been to explore the theoretical aspects of this problem and to develop the theory and the computational methods necessary to carry out accurate calculations of the the scattering process for broad categories of collider physical observables.
Data: CORDIS, © European Union
Project objective
Full exploitation of the LHC data, notably for Higgs precision measurements, traditional standard-model studies and certain BSM searches, relies on high-precision theoretical calculations. The most widely used kind of theoretical prediction is the parton-shower Monte Carlo approach (PSMC). This accounts for logarithmically enhanced contributions to all order in the coupling. While there has been much progress in the past decade in combining PSMC and fixed-order calculations, the logarithmic accuracy of the underlying parton shower has received much less attention.This project will start by developing the technology to describe the structure of the perturbative calculations at next-to-next-to-leading logarithmic (NNLL) accuracy for processes that involve QCD radiation both off the initial and the final state particles. That understanding will provide the foundations to extend for the first time the accuracy of parton showers to NNLL accuracy for a broad class of observables. Given recent developments in matching and merging of PSMCs with fixed order predictions, this will be of benefit not just for the intrinsic logarithmic accuracy of the shower but also facilitate future improvements in matching and merging, with resulting further improvements in LHC data extraction and interpretation.
Original text from CORDIS.
Participants
- ORGANISATION EUROPEENNE POUR LA RECHERCHE NUCLEAIRE · GENEVE 23CoordinatorSwitzerland
Links
Data: CORDIS, © European Union