Thursday, June 13, 2013

International Linear Collider: Technical Design Report out

Yesterday, as I learned from the CERN website and a CERN press release, the Linear Collider Collaboration (obtained by merging the officials behind ILC and CLIC) has released the ILC Technical Design Report, including a free and colorful 60-page PDF booklet.

It may be meaningful to mention Table 2.1 of that PDF file that describes the planned experiments with their center-of-mass energy.

At \(91 \GeV\), the plan is to study \(e^+e^-\to Z\), ultraprecision electroweak, and at \(160 \GeV\), one may study ultra-precision \(W\) mass via \(e^+e^-\to WW\). A big part of the early experiments would be \(e^+e^-\to Zh\) at \(250\GeV\) where this process peaks. This would be good for a precise measurement of the Higgs boson's interactions.

Center-of-mass energies \(350\)-\(400 \GeV\) would reveal top quark couplings from the \(t\bar t\) final state, precision \(W\) couplings from the \(WW\) final state, and precision Higgs coupling from the \(\nu\bar\nu h\) final state.

At \(500 \GeV\) and \(700\)-\(1000\GeV\), there would be various channels that would search for a \(Z'\) boson, Higgs compositeness, Higgs self-coupling, extended Higgs states; and the search for SUSY via the \(\tilde \chi\tilde\chi\) pair production of the Majorana particles (e.g. those of the dark matter) and from the pair production of scalar top quarks (stops) \(\tilde t \tilde t^*\).

The PDF booklet may tell you a lot about the electric fields, radio frequencies, two detectors that the collider should boast, not to mention a huge list of roughly 100 contributing institutes that harbor 1,000 scientists and engineers who have worked on the report.

There should be 7,000 collisions a second at \(500 \GeV\); 16,000 superconducting cavities guiding the beams. The booklet was ceremonially delivered to some VIPs in Europe, Asia, and the Americas. The tunnels are 31 kilometers long and the facility should be very cheap, just $7.8 billion or so, below the LHC costs.

Unrelated, two fun papers.

Don Bennett and Holger Bech Nielsen are trying to fudge a tender for the best gauge group in the Universe, with a pre-decided winner who should be the Standard Model. I agree with the general spirit that Nature may have declared such a job contest (a vacuum selection mechanism) but I think that its criteria were probably less contrived than the functions-of-Casimirs-based criteria in this paper. I also think that the job contest organized by Nature chose not only the gauge group but all other properties (matter spectrum and the parameters following from the right stringy compactification) of the Universe around us at the same moment which means that I tend to believe that any job contest that only chooses the gauge group is probably unnatural, contrived, and ultimately invalid.

Two Indian authors are trying to claim that the light, \(5\)-\(10\GeV\) particle of dark matter, may have already been near-discovered from the 1970s and 1980s due to eight of the so-called Kolář events in India (I couldn't resist to put the Czech diacritical signs because it's a rather standard Czech name).


  1. Darn, I first thought Kolar event is a technical term, until I opend the paper ... :-D

  2. The US DoE estimates the total cost of constructing the ILC to be $20B. Expect more if actually built. Actually, we may have reached the end of big physics. Considering the financial problems of the US, EU, Japan et al., ITER and LHC may be the last large research facilities ever built. Manned space flight is already dead: there will be no return to the Moon and no Mars mission. The US cannot even put a man in low earth orbit.

  3. About the Kolar events.

    We need a model of why we have not seen them at LEP, at least we have not seen anomalous missing energy.

    8 GeV mass pairs would be a piece of cake to produce. If the production cross section is so tiny how come dark matter now is five times the ordinary matter?