“ The new technique took a probabilistic approach to the measurements
gleaned from the Fermilab collider. When the accelerator smashes a quark
and an anti-quark together, a top quark and an anti-top quark are
occasionally created. These quickly decay into other particle types, which
themselves decay into yet more particles before the Fermilab detectors can
begin to study them. This means the researchers have to work backward,
looking at the third generation particles and inferring how they were made
back in time, much like looking at a scattering of pool balls and deducing
where they were three moves ago. Traditionally, researchers would assign a
mass to the initial top and anti-top quarks and figure out what the
decayed results should look like, then compare those results with what the
detectors actually saw. The new technique works similarly, but assigns
probabilities to a range of initial masses, giving more importance to the
most accurate readings. The result, when played out over many collisions,
is a measurement that’s much more precise.”
—
“ When the real-world data was parsed, the method yielded a nearly 40
percent increase in precision; less than predicted, but still a tremendous
boon to physicists. The improved method allows researchers to glean as
much information from the available data as would have been possible from
a sample two and a half times as large, which is invaluable when
collecting data from each collision is such an delicate and arduous task.
“The second major fallout from the new measurements is that the Higgs boson
- the particle that is theorized to give rise to mass itself - apparently
exists at higher energy levels than where scientists have been searching.
Since all subatomic particles are related to each other, changes in the
characteristics of one ripples through other particles, and since the top
quark is especially massive, changes to it result in the largest changes
in other particles - especially the Higgs. Based on the old accepted value
of the top quark mass, physicists expected to find the Higgs boson at
around 96 GeV/c2 (gigaelectron-volts), but have been able to rule out that
it actually exists there. That threw the whole Standard Model into a
quandary. The new measurement for the top quark mass, however, now places
the Higgs at about 117 GeV/c2, which is a range accelerators haven’t yet
searched, putting the elusive Higgs back into play.”
