When we look at the stars in the night sky, we are only looking at five percent of the universe. The rest is composed of two unknown components: 25 percent being dark matter and 70 percent being dark energy.
A new physics grant is going towards helping Florida Tech researchers better understand the properties of dark matter and the makeup of the matter content of the universe.
Florida Tech professor Marcus Hohlmann and associate professor Francisco Yumiceva in physics were recently awarded a four-year, $1.3 million grant from the U.S. Department of Energy to continue research with the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) at CERN in Geneva, Switzerland. The money will go towards sub-system upgrades to the CMS detector in order to operate the detector at higher intensities, as the rate of collisions will increase by a factor of five at the upgraded LHC.
A signature of new physics never before observed could well be hidden in the data recorded by the CMS detector. Subatomic particles such as the “top quark” are copiously produced in the LHC collisions. The top quark is the heaviest subatomic particle ever discovered – even heavier than the Higgs boson discovered in 2012. Top quarks could provide researchers with an ideal opportunity to use them as a tool to search for new physics through very precise measurements of its properties. In particular, Yumiceva’s students and postdoc are focused on studying rare processes with light-emitting top quarks.
“There are different elementary particles, like the electron, but we also have these particles called quarks,” Yumiceva said. “We will accumulate a large sample of data from the detector which will allow us to measure the rare processes involving the top quark.”
While particle physics suggests all massive particles should interact with the Higgs boson, current data are so far not sufficient to nail this down for the lighter particles. “The Higgs particle should interact with muons or electrons, but the probability for that to happen is so small that with the current data set we just can’t prove that yet, so we need larger data sets, so that’s why we’re upgrading the LHC to a higher luminosity,” Hohlmann said. The upgrade will increase the event rates and radiation load for the detectors and possibly produce dark matter from the collisions of protons.
To identify the energy and particles causing the collisions, Yumiceva and Hohlmann’s research will involve different parts of the detector. Yumiceva’s upgrade work will go towards the calorimeter detector, which measures the energy of particles created, while Hohlmann’s upgrades will go towards the muon detector, which detects and analyzes muons, a heavier version of the electron (200 times more massive).
While Hohlmann says scientists have seen an indirect indication of dark matter particles, no one has detected them yet.
“The only effect that we know of is the gravitational effect because there are these halos of dark matter that are posited to surround the galaxies, which add to their mass and gravitational force and make the galaxies rotate at a faster level than expected,” Hohlmann said. “It’s matter and has mass, but it doesn’t emit light, hence it’s dark, so it’s hard to observe.”
In order to advance closer to dark matter, the team is analyzing the possibility of “long-lived dark matter particles” that may emerge from the collisions at the LHC. Hohlmann, along with a research student, is working on simulations to gauge what those particles and collisions may look like in the CMS muon detectors and analyzing data to see if there are similar events showing up in the CMS data.