Mike Cooke

The Higgs boson and its decay products would have different event characteristics if its intrinsic spin were not the value of zero predicted by the Standard Model. While studies so far have shown that the particle discovered by the LHC experiments in 2012 is some version of a Higgs boson that appears consistent with the Standard Model, there’s a chance that a look from a different angle will put a new spin on things. To be consistent with the predictions…

Photons, the particles of light, make excellent probes of the strong-force interactions that hold the proton together. The strong force is difficult to study because gluons, the carriers of the strong force, interact with each other. This makes the inside of a proton a very busy place, since the gluons that the constituent quarks (two up and one down) exchange to bind together interact in complicated ways. On the other hand, photons, which are the particles of light and carry…

Precision measurements of top quark behavior could lead to a glimpse of new physics. The first sign of new physics may not be the direct observation of a new particle, but a glimpse of something new through its effect on known particles. Certain models of new physics would alter the behavior of top quark pair production from what the Standard Model predicts, which opens a window to look for new physics through precision studies of top quarks. Calculations based on…

The first dedicated study of Z boson plus charm quark production shows that the Z boson has more charm than predicted. Ask someone how often he’s seen a physicist with charm and you might get a wild response, but ask a physicist how often a Z boson is found with charm and—thanks to a new result from DZero—they can give you a quantitative answer. Sometimes a Z boson, the neutral weak-force carrier, is produced in association with quarks. This process…

Rare processes that produce a single top quark at a time can give insight into the nature of the weak force. Albert Einstein once stated, “The pursuit of truth and beauty is a sphere of activity in which we are permitted to remain children all our lives.” A recent analysis at DZero takes his advice in a literal search for truth and beauty. While top quarks are most commonly produced in pairs via the strong force, the W boson, a…

Pairs of photons can probe the structure of a proton and help improve the modeling of strong force interactions. A lot of activity is packed into a proton, and accurately modeling that particle maelstrom is important to measuring properties of the Higgs boson and searching for new physics. Most of a proton’s momentum is carried by its three “valence quarks,” which are two up quarks and one down quark for a proton. However, those valence quarks exchange many gluons, the…

To piece together many of the particles produced by Tevatron collisions, physicists at DZero must first piece together the muons they decayed into. To understand the subatomic world, physicists must piece together a picture of the particles made in a high-energy collision using information from detectors as large as apartment buildings. The particles recorded by a detector may themselves be the decay products of unstable particles, like a Higgs boson or a top quark, that don’t reach the detector directly….

Complementary experiments enhance the Tevatron physics program by improving searches and measurements. Two independent experiments, CDF and DZero, recorded the results of the proton-antiproton collisions provided by the Tevatron, and their complementary efforts have proven greater than the sum of their parts. Each collaboration scrutinizes its collected data, searching for signs of new physics while making precise measurements of particle properties in order to improve our understanding of the Standard Model. Comparing and combining the separate results from each collaboration…

When four force carriers directly interact, they can be used as a powerful probe for new physics. The Standard Model predicts a distinct behavior between force carrying particles when they directly interact with each other, so studying what happens when four force carriers simultaneously interact is a powerful test of the theory. By looking for a deviation from the predicted behavior, physicists can perform a generalized search for new physics without necessarily knowing what could be hiding in nature. The…

Most matter and antimatter annihilated each other in the very early universe, but a small excess of matter remained to form the universe we live in today. To attempt to understand this imbalance, scientists measure particle decay processes that show a difference between matter and antimatter. We live in a universe filled with matter, with no detectable pockets of antimatter, but don’t fully understand why. In the very early universe, matter and antimatter were created in equal abundance. As the…