{"id":11445,"date":"2021-05-12T16:17:09","date_gmt":"2021-05-12T15:17:09","guid":{"rendered":"https:\/\/www.innovationnewsnetwork.com\/?p=11445"},"modified":"2021-05-13T07:21:00","modified_gmt":"2021-05-13T06:21:00","slug":"a-circular-electron-positron-higgs-factory-for-the-world","status":"publish","type":"post","link":"https:\/\/www.innovationnewsnetwork.com\/a-circular-electron-positron-higgs-factory-for-the-world\/11445\/","title":{"rendered":"A circular electron-positron Higgs factory for the world"},"content":{"rendered":"

CEPC<\/a> Project Director, Professor Xinchou Lou, outlines the need for a new high energy electron-position collider and what the Circular Electron-Positron Collider (CEPC) could achieve.<\/h2>\n

In September 2012, soon after the Higgs boson was discovered at the Large Hadron Collider (LHC)<\/a>, Chinese particle physicists gathered in Beijing to plan for the next major accelerator project in China. What was proposed from that meeting is a high energy Circular Electron-Positron Collider (CEPC),1,2<\/sup> followed by a pp collider, named the Super Proton-Proton Collider (SppC) that will be housed in the same tunnel. The CEPC will be a Higgs factory with a centre of mass energy of 240 GeV that will enable the precision study of the Higgs beyond the capability of the LHC. The SppC will enable proton-proton collisions at 100 TeV, bringing scientists to the new energy frontier.<\/p>\n

The need for a new collider<\/h3>\n

A high energy electron-position collider with a centre of mass energy of several hundred GeV is long overdue. The new accelerator can be in the form of a straight line, like the International Linear Collider (ILC) and the Compact Linear Collider (CLIC), or a ring like the CEPC or the Future Circular Collider (FCC) proposed for Europe.<\/p>\n

Historically, new particles such as the beauty quark and the W and Z bosons had been discovered at hadron accelerators due to their high production rates in pp collisions, albeit in the presence of very high backgrounds.3<\/sup> Subsequently, these new particles have been studied in detail and many precision particle physics measurements have been carried out at electron-positron colliders.<\/p>\n

The clean environment of e+<\/sup>e–<\/sup> colliders led to the precision study of the Z, W, and perturbative QCD at the Large Electron\u2013Positron Collider (LEP)4<\/sup> that provided stringent constraint on the Standard Model and made possible the observation of the CP-violation in B meson decays at B-factories.5<\/sup> Yet, since the discovery of the top quark in 1995 and the Higgs boson in 2012, humankind has not managed to build a dedicated high-luminosity e+<\/sup>e–<\/sup> collider that will serve as a factory of the top quark or Higgs boson. A Higgs factory that can deliver high statistical samples of clean Higgs for probing the Higgs boson with a precision at 1% level or better is especially called for.<\/p>\n

In September 2013, Chinese physicists formed a study group, which is hosted by the Institute of High Energy Physics (IHEP) in Beijing. An international advisory committee, consisting of renowned scientists, experts, and former directors of major particle physics labs, has been advising the CEPC study group from a very early stage. With support and participation by international scientists, the group began the design of the CEPC accelerator and experiments, and thus the R&D of critical components. In November 2018 (see Fig. 1)., the study group went on to release the conceptual design reports (CDR) of the CEPC accelerator and the detectors. 1, 2<\/sup><\/p>\n

The CEPC accelerator<\/h3>\n

The CEPC accelerator will be installed in a 100km underground tunnel and shall deliver luminosities of 2.93\u25ca1034<\/sup>cm-2<\/sup>s-1<\/sup>, 11.5\u25ca1034<\/sup>cm-2<\/sup>s-1<\/sup>, and 32.1\u25ca1034cm-2<\/sup>s-1<\/sup>, at the Higgs (240 GeV), the W (160 GeV), and Z (91 GeV) energies, respectively. The CEPC collider complex consists of a linear accelerator (Linac), a damping ring (DR), the booster ring, the electron and positron storage rings, and several transport lines. In the CDR, there will be two interaction points where detectors with high precision tracking and PFA-capable high granularity calorimeters will be operated. The tunnel is ~6m wide, sufficiently large to allow for a future Super proton-proton Collider (SppC) without dismantling the electron accelerator, thus preserving opportunities for future electron-positron and electron-ion physics programs. The CEPC is envisioned to be a large international scientific project.<\/p>\n

Since the release of the CDR, the CEPC study group has devoted much effort to enhancing the design of the CEPC collider and executing the R&D programme with a focus on innovation.<\/p>\n

Design enhancement and better understanding of the physics potential<\/h3>\n

The optimised CEPC accelerator design, with reduced machine parameters \u03b2y* and the emittance, by moving the final focus closer to the interaction point and adopting a smaller and thinner beam pipe, along with several other improvements, has achieved increases in luminosity of 70%, 63%, and 229% for the Higgs, the W, and the Z, respectively.<\/p>\n

The group has planned several upgrade paths, including:<\/p>\n