scholarly journals FCC: Building on the shoulders of giants

2021 ◽  
Vol 136 (10) ◽  
Author(s):  
Stephen Myers

AbstractThe plethora of open questions in particle physics, the new chapter opened by the Higgs boson, and the lack of clear theoretical guidance as to where new theory could lie call for a broad and diverse experimental programme boosting the intensity and energy-frontier. The proposed FCC-integrated programme consisting of a luminosity-frontier highest-energy lepton collider followed by an energy-frontier hadron collider promises the most far-reaching particle physics programme that foreseeable technology can deliver. In this essay, particular emphasis is given to the lessons from the predecessor of the LHC, LEP, which was commissioned in 1989 and finished operation in November 2000.

2019 ◽  
Vol 206 ◽  
pp. 08001
Author(s):  
Tadeusz Lesiak

A future giant electron-positron collider, operating at the energy frontier, is a natural proposal in order to push particle physics into new regime of precise measurements, in particular in the sectors of electroweak observables and Higgs boson parameters. The four projects of such accelerators: two linear (ILC and CLIC) and two circular (FCC and CEPC) are currently in various stages of development. In view of the update of European HEP strategy for particle physics and expectations of important decisions from Japan, China and USA, the next few years will be critical as far as the decisions about the construction of such colliders are concerned. The paper concisely reviews the relevant aspects and challenges of the proposed accelerators and detectors along with the presumed schedules of construction and operation. The motivation and very attractive physics program for new e+e− colliders, spanning in particular perspectives in Higgs, electroweak, and neutrino sectors, together with expectations of searches for New Physics, will be discussed as well.


2014 ◽  
Vol 03 (02) ◽  
pp. 23-24
Author(s):  

A team of physicists from Hong Kong has now formally joined one of the most prestigious physics experiments in the world. Following a unanimous vote of approval today by its Collaboration Board, ATLAS has admitted the Hong Kong team as a member. The ATLAS Collaboration operates one of the largest particle detectors in the world, located at the Large Hadron Collider (LHC), the world's highest energy particle accelerator at CERN, Switzerland. In 2012, the ATLAS team — along with the CMS Collaboration — co-discovered the Higgs boson, or so-called 'God Particle'. The gigantic but sensitive and precise ATLAS detector, together with the unprecedentedly high collision energy and luminosity of the LHC, make it possible to search for fundamentally new physics, such as dark matter, hidden extra dimensions, and supersymmetry — a proposed symmetry among elementary particles. The LHC is currently undergoing an upgrade, targeting a substantial increase in beam energy and intensity in a year's time. It is widely expected that the discovery of the Higgs boson is only the beginning of an era of new breakthroughs in fundamental physics. All these exciting opportunities are now opened up to scientists and students from Hong Kong.


2020 ◽  
Vol 18 ◽  
pp. 110-142
Author(s):  
Abdeljalil Habjia

In the context of particle physics, within the ATLAS and CMS experiments at large hadron collider (LHC), this work presents the discussion of the discovery of a particle compatible with the Higgs boson by the combination of several decay channels, with a mass of the order of 125.5 GeV. With increased statistics, that is the full set of data collected by the ATLAS and CMS experiments at LHC ( s1/2 = 7GeV and s1/2 = 8GeV ), the particle is also discovered individually in the channel h-->γγ with an observed significance of 5.2σ and 4.7σ, respectively. The analysis dedicated to the measurement of the mass mh and signal strength μ which is defined as the ratio of σ(pp --> h) X Br(h-->X) normalized to its Standard Model where X = WW*; ZZ*; γγ ; gg; ff. The combined results in h-->γγ channel gave the measurements: mh = 125:36 ± 0:37Gev, (μ = 1:17 ± 0:3) and the constraint on the width Γ(h) of the Higgs decay of 4.07 MeV at 95%CL. The spin study rejects the hypothesis of spin 2 at 99 %CL. The odd parity (spin parity 0- state) is excluded at more than 98%CL. Within the theoretical and experimental uncertainties accessible at the time of the analysis, all results: channels showing the excess with respect to the background-only hypothesis, measured mass and signal strength, couplings, quantum numbers (JPC), production modes, total and differential cross-sections, are compatible with the Standard Model Higgs boson at 95%CL. Although the Standard Model is one of the theories that have experienced the greatest number of successes to date, it is imperfect. The inability of this model to describe certain phenomena seems to suggest that it is only an approximation of a more general theory. Models beyond the Standard Model, such as 2HDM, MSSM or NMSSM, can compensate some of its limitations and postulate the existence of additional Higgs bosons.


2014 ◽  
Vol 29 (04) ◽  
pp. 1430004 ◽  
Author(s):  
Dezső Horváth

The 40 years old Standard Model, the theory of particle physics, seems to describe all experimental data very well. All of its elementary particles were identified and studied apart from the Higgs boson until 2012. For decades, many experiments were built and operated searching for it, and finally, the two main experiments of the Large Hadron Collider (LHC) at CERN, CMS and ATLAS, in 2012 observed a new particle with properties close to those predicted for the Higgs boson. In this paper, we outline the search story: the exclusion of the Higgs boson at the Large Electron Positron (LEP) collider, and its observation at LHC.


2015 ◽  
Vol 23 (1) ◽  
pp. 57-70
Author(s):  
Aleandro Nisati

The Large Hadron Collider (LHC) at CERN is the highest energy machine for particle physics research ever built. In the years 2010–2012 this accelerator has collided protons to a centre-mass-energy up to 8 TeV (note that 1 TeV corresponds to the energy of about 1000 protons at rest; the mass of one proton is about 1.67×10–24 g). The events delivered by the LHC have been collected and analysed by four apparatuses placed alongside this machine. The search for the Higgs boson predicted by the Standard Model and the search for new particles and fields beyond this theory represent the most important points of the scientific programme of the LHC. In July 2012, the international collaborations ATLAS and CMS, consisting of more than 3000 physicists, announced the discovery of a new neutral particle with a mass of about 125 GeV, whose physics properties are compatible, within present experimental and theoretical uncertainties, to the Higgs boson predicted by the Standard Model. This discovery represents a major milestone for particle physics, since it indicates that the hypothesized Higgs mechanism seems to be responsible for the masses of elementary particles, in particular W± and Z0 bosons, as well as fermions (leptons and quarks). The 2013 Physics Nobel Prize has been assigned to F. Englert and P. Higgs, ‘for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN's Large Hadron Collider’.


Author(s):  
Rolf-Dieter Heuer

This paper presents the Large Hadron Collider (LHC) and its current scientific programme and outlines options for high-energy colliders at the energy frontier for the years to come. The immediate plans include the exploitation of the LHC at its design luminosity and energy, as well as upgrades to the LHC and its injectors. This may be followed by a linear electron–positron collider, based on the technology being developed by the Compact Linear Collider and the International Linear Collider collaborations, or by a high-energy electron–proton machine. This contribution describes the past, present and future directions, all of which have a unique value to add to experimental particle physics, and concludes by outlining key messages for the way forward.


Author(s):  
G. Dissertori

Enormous efforts at accelerators and experiments all around the world have gone into the search for the long-sought Higgs boson, postulated almost five decades ago. This search has culminated in the discovery of a Higgs-like particle by the ATLAS and CMS experiments at CERN's Large Hadron Collider in 2012. Instead of describing this widely celebrated discovery, in this article I will rather focus on earlier attempts to discover the Higgs boson, or to constrain the range of possible masses by interpreting precise data in the context of the Standard Model of particle physics. In particular, I will focus on the experimental efforts carried out during the last two decades, at the Large Electron Positron collider, CERN, Geneva, Switzerland, and the Tevatron collider, Fermilab, near Chicago, IL, USA.


2014 ◽  
Vol 29 (27) ◽  
pp. 1430062 ◽  
Author(s):  
Sau Lan Wu

In 1964, a new particle was proposed by several groups to answer the question of where the masses of elementary particles come from; this particle is usually referred to as the Higgs particle or the Higgs boson. In July 2012, this Higgs particle was finally found experimentally, a feat accomplished by the ATLAS Collaboration and the CMS Collaboration using the Large Hadron Collider at CERN. It is the purpose of this review to give my personal perspective on a brief history of the experimental search for this particle since the '80s and finally its discovery in 2012. Besides the early searches, those at the LEP collider at CERN, the Tevatron Collider at Fermilab, and the Large Hadron Collider at CERN are described in some detail. This experimental discovery of the Higgs boson is often considered to be one of the most important advances in particle physics in the last half a century, and some of the possible implications are briefly discussed. This review is based on a talk presented by the author at the conference "OCPA8 International Conference on Physics Education and Frontier Physics," the 8th Joint Meeting of Chinese Physicists Worldwide, Nanyang Technological University, Singapore, June 23–27, 2014.


2013 ◽  
Vol 22 (07) ◽  
pp. 1330015
Author(s):  
◽  
DOMIZIA ORESTANO

This document presents a brief overview of some of the experimental techniques employed by the ATLAS experiment at the CERN Large Hadron Collider (LHC) in the search for the Higgs boson predicted by the standard model (SM) of particle physics. The data and the statistical analyses that allowed in July 2012, only few days before this presentation at the Marcel Grossman Meeting, to firmly establish the observation of a new particle are described. The additional studies needed to check the consistency between the newly discovered particle and the Higgs boson are also discussed.


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