Synopsis: W Marks the Spot

Two experimental collaborations at Fermilab report a new measurement of the W boson mass that leads to a better prediction of the mass of the Higgs boson.
Synopsis figure

Long before experimentalists at the Large Hadron Collider reported hints of the Higgs boson in particle collisions (see 13 March 2012 Viewpoint), physicists knew roughly what the Higgs mass had to be from measurements of the W boson. That’s because according to the standard model, the W boson, one of the particles that mediates the weak interaction, can emit a virtual Higgs boson and reabsorb it, which alters the W boson’s mass. The mass of the W boson also shifts due to a virtual process containing a top and bottom quark. So with a precise measurement of the W mass, and a good measurement of the top quark mass, it is possible to predict the mass of the Higgs boson.

Now the CDF and D0 Collaborations at Fermilab are each reporting in Physical Review Letters their new measurements of the W mass using datasets containing a total of about 2 million W decays to an electron or muon and a neutrino. By analyzing the kinematics from this large sample, the two experiments achieve a combined precision of about 0.02%.

These new values narrow the allowed range in top-W mass space. The band of top-W masses corresponding to the 115–127 GeV range of Higgs masses, allowed by direct searches, goes right through the allowed region determined by CDF and D0. If the LHC does find the Higgs boson in the 115–127 GeV mass window, it will be yet another success for the predictions of the standard model. – Robert Garisto


Features

More Features »

Announcements

More Announcements »

Subject Areas

Particles and Fields

Previous Synopsis

Chemical Physics

Only on Paper

Read More »

Next Synopsis

Semiconductor Physics

Nanowire Lasing Explained

Read More »

Related Articles

Focus: Muons Reveal Record-Breaking Thunderstorm Voltage
Geophysics

Focus: Muons Reveal Record-Breaking Thunderstorm Voltage

A thunderstorm probed with atmospheric muons had an electric potential exceeding one billion volts, much higher than values measured previously.   Read More »

Synopsis: A Lens for Millimeter-Sized Electron Accelerators
Particles and Fields

Synopsis: A Lens for Millimeter-Sized Electron Accelerators

An array of silicon pillars could focus and confine an electron beam in future computer-chip-sized electron accelerators, allowing faster acceleration of electrons using this technology. Read More »

Synopsis: Putting the Proton Radius in Its Proper Place
Particles and Fields

Synopsis: Putting the Proton Radius in Its Proper Place

An analysis of the proton radius puzzle helps to define what the proton radius really means. Read More »

More Articles