Thursday, December 17, 2009

Dark matter live webcast

Ok, a litle bit late, but still something is going on:

Fermilab webcast in dark matter CDMSresults

Or, if you prefer you can watch the other simultaneous conference:

As I am posting late just tell that the main announcement has been already made, two events. That means not a definitive discovering, because of statistical considerations, but certainlly something. Now they are preciselly discusing exactly how significant this is.

Update: If you want to see a summary of the results by the CDMS team, get it here (it is a two pages pdf, without formulae, readable for most people).

Quick summary, as said in CF: if these events are interpreted as signal, the lower bound on the WIMP mass for these recoil energies is roughly 0.5 GeV.

I would add, a good guess (it gives the best possible cross-section) is a 70 GeV WIMP. DAMA claims of dark matter discovering, via inelastic dark matter (that is the WIMP has excited energy state) is compatible with CDMS results in a reasonable parameter range.

I invite you to read the entries on the topic in many of the blogs in my link list (and possibly many others). Although not a discovering there will be a lot of discussion about these results in the near future. And new results are announced for the future, when the new superCDMS would be working.

Update: You can see the recorded video of one of the conferences from this website:

The arxiv paper, still not submitted when I am posting this, is availabe here

There are some discussion in the blogs about the actual relevance of the signal. The most accepted one is a 1.5 sigma result. The discrepancies differ in how to actually consider the background. The data of 1.3 goes with the blinded background (optimized background obtained without knowledge of the existence of the signals). If one use other background one could get as much as (almost) 3 sigmas, or as few as 0. By the way, the very use of "sigma" is more appropriate for gaussian distributions, but it is used commonly for non gaussian ones with the appropriated corrections.

For the future I have read that before de superCDMS it is expected to have data from another experiment, the XENON100. They talk about "early in the 2010". It remains to see what "early" exactly means, and -more important- what the results are.

If one wants to read an easy introduction to the detailss of how CDMS works one can read this entry in the old tomasso dorigo blog. Be aware that Dorigo dosn't like too much supersymmetry and it argues that the (previous) CDMS result convince him a little bit more about that. Curiously he hasn't any entry about this new CDMS dataset.

I had not time to answer Matti to a question in the previous post. I leave here a link to his own view of these results as a compensation:

No comments: