One of the mysteries of our universe lies in its earliest moments, as the most reliable physics models we currently have note that the universe should have collapsed shortly after its inflation, which occurred for a fraction of a second after the Big Bang. This is because Higgs bosons, which were created during this inflation and are key to explaining the masses of various other particles, should have created a large enough Higgs field to cause the collapse of the universe.
Now, researchers from the University of Copenhagen believe that they have come one step closer to solving this problem in a study in which they constrained the strength of the coupling between the Higgs field and gravity, the last unknown factor in the standard model.
Physicists believe that the stronger the bond between the Higgs field and gravity, the larger the fluctuations, which increase the chances of a fatal transition to a vacuum state consisting of negative energy. However, the scientists calculated that a collapse would only occur after inflation if the Higgs-gravity coupling strength was above the value of one.
Although Higgs-gravity coupling strength may be the key to explaining why the universe did not collapse upon itself during its early moments, further research will need to be conducted until conclusive evidence is found.
"It's a combination of parameters that actually determines the occurrence of such a transition, including the Higgs coupling to gravity, but also the energy scale of the inflation, which are not tightly constrained by current measurements," Matti Herranen, co-author of the study, told Phys.org.
"So, presently it is not possible to draw a conclusion on whether the standard model is in trouble due to instability-related issues, but it would be very interesting if the Higgs-gravity coupling and the scale of inflation could be constrained more tightly in the future by independent measurements, for example by observing primordial gravity waves from inflation," Herranen said.
The findings were published in the Dec. 11 issue of Physical Review Letters.
