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University of Cincinnati Professor Shining Light on Dark Matter

As a High School Student, Stefania Gori visited CERN, one of the world’s most refined laboratories, when its Large Hadron Collider was only a hole in the ground hundreds of feet below Geneva, Switzerland.

UC Assistant Professor Stefania Gori and her students use a blackboard in her office to work out theoretical physics concepts. Credit: University of Cincinnati

The University of Cincinnati Theoretical Physicist is currently inspiring experiments there using her own ideas about her ultimate research subject, dark matter.

Visiting CERN played a big role for me in deciding to push for particle physics as my career. It’s a dream to imagine a future involved in these big experiments and active research.

Stefania Gori, Theoretical Physicist, University of Cincinnati

Dark matter makes up most of the known universe. This is yet to be observed, but Scientists are indeed confident that dark matter is out there influencing galaxies, stars and planets.

As an Assistant Professor of Physics, in UC's McMicken College of Arts & Sciences, Gori is presently shaping how Researchers learn about dark matter at some of the most sophisticated labs on Earth. Scientists at pioneering institutions such as Fermilab outside Chicago and the SLAC National Accelerator Laboratory at Stanford University have gained knowledge from Gori’s ideas.

Physicists are divided into two camps: experimental and theoretical.  However, Gori tries to bridge both worlds having succeeded in publishing more than 30 papers on elementary particles and dark matter.

My field is in the middle. I’m a theorist. But I’m developing these theories and trying to design experiments in such a way to test them.

Stefania Gori, Theoretical Physicist, University of Cincinnati

This year, Gori’s efforts were acknowledged by the National Science Foundation that awarded her a $400,000 grant to pursue her research.

“Particle physics faces two fundamental problems that point to ‘new physics’ lying beyond our current understanding,” the foundation’s grant award said.

The first focuses on how to explain the origin of the mass of the lately discovered Higgs boson particle. The second question deals with the nature and origin of dark matter, which occupies over five times as much mass as the remainder of the known universe.

“As part of her proposed research, Gori will pursue an ambitious research program focused on studying these two fundamental problems at the interface between high-energy and high-intensity experiments,” the foundation award said.

Dark matter is known as “dark” since it does not absorb, create or reflect light. However, the name might as well be an allusion to the mystery that surrounds it.

We know very little about it. There are lots of candidate theories for dark matter. And we don’t know which, if any of them, could be right. They could all be wrong.

Richard Gass, Physics Professor, University of Cincinnati

Scientists experience challenges in answering some of the big questions posed by dark matter. However, Gass stated that Gori’s work definitely will raise tantalizing new ones.

“Answering them will depend on how the experiments go,” Gass said.

According to Scientists, the expansion of the universe accelerates instead of slowing down because of dark energy, which indeed is considered to be the theoretical reason. Scientists naturally expect to find the universe expanding at an extremely slower rate due to the forces of gravity. However, observations by the Hubble space telescope discovered that the opposite was true – the universe is presently expanding at a faster rate than it was long ago.

“There is evidence of dark matter from looking at the location of galaxies,” Gori said. “The location of galaxies is different from what we would have expected. The reason is dark matter.”

Dark energy is considered to be responsible for 68% of the energy in the universe Dark matter takes up 27% or more. The measly remainder, which is less than 5%, is made up of suns, moons, planets, humans and all other observable matter.

“What we have discovered from physics is there is much more matter than what we have observed,” Gori said.

Gori’s mission is taking her back to CERN, where she works along with Experimental Physicists from all over the world who are responsible for testing her hypotheses using instruments such as the atom-smashing Large Hadron Collider.

The collider makes use of superconducting magnets in order to send protons dashing at the speed of light in opposite directions around a ring the size of Cincinnati. These protons hit against each other and produce 14 trillion electron volts of energy. That sounds both scary and impressive. But CERN states that it is equivalent to the energy a mosquito applies to fly. The difference lies in the fact that this energy is developed by matter a trillion times smaller than the buzzing insect.

Gori is attempting to comprehend the properties of the Higgs boson, an elementary particle discovered in 2012 at CERN. Sometimes, it is called “the God particle” for its central role in understanding matter. She is also exploring the nature of dark matter and enabling to come up with novel experiments in order to test those ideas.

This teamwork with Experimental Physicists from all over the globe is considered to be the most rewarding aspect of her career, she stated.

“The part of research I find super-interesting is to be the interface between theory and experiment,” she said. “This is a back and forth between theorists and experimental physicists. I find this very exciting. We’re trying to define this new phenomena together.”

Often, physics studies involve global teamwork. However, this is particularly true of particle physics, UC’s Gass said.

“Particle accelerators are so expensive and there are only a handful in the world,” Gass said. “The cutting-edge ones have to be built through international collaboration.”

Gori, however, is accustomed to working with foreign colleagues.

As a native of Italy, Gori earned Undergraduate and Graduate degrees from the University of Pisa prior to obtaining her PhD in Theoretical Particle Physics from Technical University Munich. She has traveled all over the world, working with and speaking to Physicists at private and public Universities from Bonn to Boston to Beijing.

In 2016, Gori delivered a lecture on Physics to an all-girls Catholic high school in Cincinnati. She regularly contributes to Women in Science and Engineering and also advocates for women in science, technology, engineering and math (STEM).

“It has been demonstrated that the main reason women are discouraged from pursuing an academic career in physics is they lack role models,” she said. “I am trying to get more women involved in physics. It’s important to have role models that will inspire the next generation of women in STEM fields.”

UC’s Gass stated that Gori’s work at CERN and several other labs brings honor to UC and its Physics Department.

“It helps to raise the visibility of the institution, place your students in good post-doctoral programs and recruit good graduate students,” he said.

According to Gass, theorists must often wait a long time for their blackboard concepts to be put to the test by Experimental Physicists. But Gori and other such theorists frequently play a central role in experiments

That’s particularly important for dark-matter research. We don’t know much about it. So if you’re designing an experiment to detect dark matter, it’s important to know what signal you’re looking for and have an idea about how dark matter interacts with normal matter.

Richard Gass, Physics Professor, University of Cincinnati

Gori is excited to find out. She suspects the possibility of dark matter to comprise of its own photons – dark photons. Last year, CERN greenlighted a new experiment to study the question.

In March, CERN’s Dark Matter Working Group in which Gori works suggested a new way for studying the possible interaction between normal matter and dark matter using the Large Hadron Collider.

“That’s a big mystery. We don’t know how dark matter behaves. The question is: does dark matter interact with the Higgs boson?” she said. “There are ideas that tell us dark matter comes with additional force. We’re trying to understand these properties. Is it alone? Or does it bring a set of additional particles?”

This summer, Scientists at CERN announced the discovery of a new subatomic particle, nicknamed Xi, that Theoretical Physicists assumed they would be able to find. Gori is keen on the prospect of testing her theories about dark matter via similar experimentation.

“We don’t know when the next big discovery will happen,” Gori said. “It’s been an interesting journey.”

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