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Mercury February 10, 2007

Posted by dorigo in Uncategorized.
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Well, it looks like today I am in browsing rather than writing mood… I have been checking most of my colleagues’ blogs and left lots of comments around. And I got to read a great deal of interesting stuff, too!

Anyway, Mercury. The element, not the planet. Jennifer Ouellette has a great post on the history of mercury poisoning and a few satellite stories at her site. Check it out!

Comments

1. Helge - February 10, 2007

Hi T.

Just a little off-topic question. I wonder, if anybody thinks of discovering “gravitons” at LHC,…. It didn’t show up at https://dorigo.wordpress.com/2007/02/02/what-will-be-the-next-discovery/.

Cheers,
Helge

2. dorigo - February 11, 2007

Hi Helge,

well, I think gravitons will be sought with enthusiasm at the LHC, especially since a few of their production signatures are important also in searches for SuperSymmetry. The reason you do not see the graviton in the pie of future discoveries is that it is hidden in the “large extra dimensions” slice.

Both the graviton (either a Kaluza-Klein excitation in n>1 extra dimension models, or the so-called Randall-Sundrum graviton) and the supersymmetric gravitino can be detected, if they exist, in hadronic collisions of high enough energy. In fact they have already been sought for at the Tevatron; one straightforward way is to look for events with a high-energy jet recoiling against “missing” energy. The production processes involve a gluon recoiling against the gravit-on (-ino), which may leave the detector unseen, thereby resulting in a large imbalance in the transverse energy measured by the calorimeter.

See here for the gravitino and here for the RS or here for the KK graviton searches performed by CDF in that final state, for instance. Or this paper for a search in the final state of a high-energy photon recoiling against, again, missing energy.

As for D0, they published their latest graviton searches in PRD 90 (2003), 251802 (sorry, no link) and PRL 95, 091801 (2005); for large extra dimension searches in the dimuon final state see PRL 95 (2005) 161602.

The LHC discovery reach for these particles is of course much higher. A graviton can be seen as a high-mass resonance of two photons, for instance, or an electron-positron pair. CMS and ATLAS have a discovery reach well in excess of 2 TeV for the graviton mass in these decay modes, provided 100 fb-1 of integrated luminosity are collected, and the coupling of the graviton to standard model particles is not too weak.

Cheers,
T.


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