## Thursday, February 23, 2012

### CDF: W-boson mass is 80.387 GeV

Speedy neutrinos are so yesterday, as Katie Yurkewicz said. What is hot today is the new accurate W-boson mass as measured by the CDF at the Tevatron.

A special seminar is beginning right now, at 10 a.m. Chicago Winter Time. Watch it live here. Direct link to Flash. However, you may already see some texts:
Higgs Boson Gets New Mass Limit (Duke Today)

World's best measurement of W boson mass tests Standard Model, Higgs boson limits (Fermilab Today)
The new accurate value of the W-boson rest mass/energy is
$$m_W c^2 = 80.387 \pm 0.019 \,\,{\rm GeV}$$
Here is a graph...

The graph shows that the slightly improved accuracy of the mass measurement makes the 115-127 GeV interval for the Higgs boson even more likely than it was before (by a little bit) but one can't make more accurate conclusions about the Higgs from this W-boson mass measurement, aside from the fact that the Higgs boson is pretty light.

Using this measurement and the Standard Model, the new upper limit on the Higgs mass is 145 GeV. Of course, we know a bit better from the LHC but everything seems consistent at this point.

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