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Four Physicists Present: “How Does the ILC Case Depend on the LHC?” - 25 August

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At Thursday evening’s forum, “How does the ILC case depend on the LHC ?" Sven Heinemeyer of CERN, Michael Peskin of SLAC, Chris Damerell of Rutherford Lab and Joe Lykken of Fermilab, presented their views about the relationship between the proposed International Linear Collider and the Large Hadron Collider now nearing completion at CERN. Jonathan Bagger, a theorist from Johns Hopkins University and member of the HEPAP sub-panel on LHC/ILC physics, introduced the debate. “What is the relationship between the ILC and LHC?” Bagger asked.“We need an answer that we can support and defend,” he said. “The ILC competes with important societal goals. For that reason, the ILC needs an ironclad physics case, but it also needs more. It needs a case so compelling that the government, physicists and the public at large support the project. We all need to work together to present a clear and compelling case – one that inspires the public and excites the imagination.”

Heinemeyer and Damerell argued that ILC construction should be independent of results from the LHC.

“Why do I oppose the link between the ILC and LHC?” asked Damerell. “Two words – ‘unpredictable delay.’ The LHC is the most complex system ever built, and there could be problems with the machine, detectors, and understanding the data. These are all reasons why we shouldn’t wait for the LHC.” Heinemeyer explained that he was not arguing against the LHC. “I have nothing against the LHC,” he said. “It is a great machine, but it cannot get the precise measurements that the ILC can achieve. The ILC has always had a compelling physics case that is independent of LHC data.”

Peskin and Lykken argued that synergy with the LHC helps the case for the ILC. Despite disagreements over the relationship between the two machines, all four participants agreed that the physics case for the both the LHC and the ILC is very strong.

“We have made a very strong and compelling case for the ILC, and you should be proud of that,” said Lykken. “But we have only just begun the process of communication. We should understand that difference.” Lykken emphasized the need to focus on pushing the ILC R&D forward. “Let’s focus on getting the ILC R&D program going,” he said. “In that step, the linkage to the LHC is all positive. The fact that the LHC is turning on in two years helps us argue that we need to do this R&D now.”

Slides from Sven Heinemeyer (pdf)
Slides from Chris Damerell (pdf)