Fermilab Today Friday, Aug. 12, 2011
CMS Result

Searching for heavy cousins

A recent article set a limit on the mass of the W', a hypothetical cousin of the W boson. While that measurement is still valid, the CMS result described here sets a bigger limit still. (Clifford is a registered trademark of Norman Bridwell.)

There are a lot of things we don't understand about the subatomic realm, which is why we spend so much time studying it. Mysteries are fascinating, but maddening. My personal favorite conundrum stems from the knowledge that the up and down quarks are all that is necessary to make up the protons and neutrons of ordinary matter. We simultaneously know of two other pairs of quarks (charm and strange and top and bottom) that seem to be carbon copies of the up and down quarks, but heavier. The familiar electron has its own carbon copies.

These duplicates seem to me to be an enormous clue, screamed by the universe, telling us about some deeper and more fundamental physics.

These physicists played a role in the publication of the first CMS W' paper.

The EVO global scale videoconferencing system, developed by members of the CMS collaboration at Caltech University, allows CMS scientists to communicate on a daily basis. These people authored and built the system, and they are responsible for its continuous development and seamless functioning. Additional support is provided by a team of Slovakian scientists and engineers.

We also know of subatomic particles that carry the force holding together the universe. These particles are the gluon, photon, W & Z boson and the hypothetical graviton. For the force carrying particles, only one of each kind exists. But it's completely possible that these particles also have heavy cousins. Indeed, there are searches underway for heavier versions of all of these force-carrying particles.

An earlier Result of the Week described a search performed at the Tevatron looking for the W' (pronounced W-prime,) a heavier cousin of the W boson. Today's article tells the tale of when CMS joined the party.

The DZero measurement ruled out the existence of W' bosons lighter than about 900 times heavier than a proton. If the W' exists, it's heavy. Using the equivalent amount of beam delivered by the Tevatron in just four days, CMS published a paper ruling out W' bosons with less than about 1,600 times the mass of a proton. And last week at the EPS conference, CMS announced a result that said that, if the W' boson exists, it must have a mass at least 2,300 times the mass of the proton.

As the torrent of data pours in from the LHC, the situation is highly fluid. The searches improve dramatically every month. We expect to report a steady stream of measurements will be reported, and some of these may perhaps culminate in a discovery. Either way, our knowledge is evolving very rapidly and I hope you'll keep an eye on these extremely exciting times.

Don Lincoln

Fermi National Accelerator - Office of Science / U.S. Department of Energy | Managed by Fermi Research Alliance, LLC.
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