No Arabic abstract
This report summarizes the progress in the study of Higgs physics at a future linear electron positron collider at center-of-mass energies up to about 1000 GeV and high luminosity. After the publication of the TESLA Technical Design Report, an extended ECFA/DESY study on linear collider physics and detectors was performed. The paper summarizes the status of the studies with main emphasis on recent results obtained in the course of the workshop.
We study the potential of the TESLA linear collider operated at a center-of-mass energy of 500 to 1000 GeV for the measurement of the neutral Higgs boson properties within the framework of the MSSM. The process of associated Higgs boson production with subsequent decays of Higgs bosons into b-quark and tau-lepton pairs is considered. An integrated luminosity of 500 fb^{-1} is assumed at each energy. The Higgs boson masses and production cross sections are measured by reconstructing the bbbb and bbtautau final states. The precision of these measurements is evaluated in dependence of the Higgs boson masses. Under the assumed experimental conditions a statistical accuracy ranging from 0.1 to 1.0 GeV is achievable on the Higgs boson mass. The topological cross section sigma(e+e- -> HA -> bbbb) can be determined with the relative precision of 1.5 - 6.6 % and cross sections sigma(e+e- -> HA -> bb tautau) and sigma(e+e- -> HA -> tautau bb) with precision of 4 - 30 %. Constraints on the Higgs boson widths can be set exploiting bbtautau channel. The 5sigma discovery limit corresponds to the Higgs mass of around 385 GeV for the degenerate Higgs boson masses in the HA -> bbbb channel at sqrts = 800 GeV with integrated luminosity of 500 fb^{-1}. The potential of the Higgs mass determination for the benchmark point SPS 1a for the process e+e- -> HA -> bbbb at sqrt{s} = 1 TeV and luminosity 1000 fb^{-1} is investigated.
We report the important topics in ACFA report as well as the recent progress in the ACFA Higgs working group.
We perform comparative studies for four types of the two Higgs Doublet Models (2HDMs) under the precision measurements of the Standard Model (SM) Higgs observables at the proposed Higgs factories. We explore the discovery potential based on the hypothetical deviations in the precision data for the 2HDMs up to one-loop level. We find $5sigma$ observability from the $chi^2$ fitting in a significant theory parameter space at future Higgs factories. For the Type-I 2HDM, regions with $cos(beta-alpha)lesssim -0.1$ or $cos(beta-alpha)gtrsim 0.08$ are discoverable at more than $5sigma$ level. For the other three types of 2HDMs, the $5sigma$ region is even bigger: $|cos(beta-alpha)|gtrsim 0.02$ for $tanbetasim 1$. At small and large values of $tanbeta$, the region in $cos(beta-alpha)$ is further tightened. We examine the extent to which the different 2HDM theories may be distinguishable from one to the other at the $95%$ Confidence Level with four benchmark points as case studies. We show that a large part of the parameter space of the other types of 2HDMs can be distinguished from the benchmark points of the target model. The impacts of loop corrections are found to be significant in certain parameter regions.
This document aims to provide an assessment of the potential of future colliding beam facilities to perform Higgs boson studies. The analysis builds on the submissions made by the proponents of future colliders to the European Strategy Update process, and takes as its point of departure the results expected at the completion of the HL-LHC program. This report presents quantitative results on many aspects of Higgs physics for future collider projects of sufficient maturity using uniform methodologies. A first version of this report was prepared for the purposes of discussion at the Open Symposium in Granada (13-16/05/2019). Comments and feedback received led to the consideration of additional run scenarios as well as a refined analysis of the impact of electroweak measurements on the Higgs coupling extraction.
Precision measurement of the stop mass at the ILC is done in a method based on cross-sections measurements at two different center-of-mass energies. This allows to minimize both the statistical and systematic errors. In the framework of the MSSM, a light stop, compatible with electro-weak baryogenesis, is studied in its decay into a charm jet and neutralino, the Lightest Supersymmetric Particle(LSP), as a candidate of dark matter. This takes place for a small stop-neutralino mass difference.