Gravitational waves could be key to answering why more matter was left
over after Big Bang

Date:
December 8, 2021
Source:
Kavli Institute for the Physics and Mathematics of the Universe
Summary:
If researchers can detect Q-balls in gravitational waves, it could
help explain why more matter than anti-matter was left over after
the Big Bang.



FULL STORY ==========================================================================
A team of theoretical researchers have found it might be possible to
detect Q- balls in gravitational waves, and their detection would answer
why more matter than anti-matter to be left over after the Big Bang,
reports a new study in Physical Review Letters.


==========================================================================
The reason humans exist is because at some time in the first second
of the Universe's existence, somehow more matter was produced than
anti-matter. The asymmetry is so small that only one extra particle
of matter was produced every time ten billion particles of anti matter
were produced. The problem is that even though this asymmetry is small,
current theories of physics cannot explain it. In fact, standard theories
say matter and anti matter should have been produced in exactly equal quantities, but the existence of humans, Earth, and everything else in
the universe proves there must be more, undiscovered physics.

Currently, a popular idea shared by researchers is that this asymmetry
was produced just after inflation, a period in the early universe when
there was a very rapid expansion. A blob of field could have stretched
out over the horizon to evolve and fragment in just the right way to
produce this asymmetry.

But testing this paradigm directly has been difficult, even using the
largest particle accelerators in the world, since the energy involved is billions to trillions of times higher than anything humans can produce
on Earth.

Now, a team of researchers in Japan and the US, including Kavli Institute
for the Physics and Mathematics of the Universe Project Researcher
Graham White, and Visiting Senior Scientist Alexander Kusenko, who is
also a Professor of Physics and Astronomy at UCLA, have found a new way
to test this proposal by using blobs of field known as Q-balls.

The nature of Q-balls is a bit tricky to understand, but they are bosons
like the Higgs boson, explains Graham White, lead author and Project
Researcher at Kavli IPMU.

"A Higgs particle exists when the Higgs field is excited. But the Higgs
field can do other things, like form a lump. If you have a field that
is very like the Higgs field but it has some sort of charge -- not an
electric charge, but some sort of charge -- then one lump has the charge
as one particle. Since charge can't just disappear, the field has to
decide whether to be in particles or lumps. If it is lower energy to be
in lumps than particles, then the field will do that. A bunch of lumps coagulating together will make a Q-ball." "We argue that very often these blobs of field known as Q-balls stick around for some time. These Q-balls dilute slower than the background soup of radiation as the Universe
expands until, eventually, most of the energy in the Universe is in
these blobs. In the meantime, slight fluctuations in the density of the
soup of radiation start to grow when these blobs dominate. When the Q-
balls decay, their decay is so sudden and rapid that the fluctuations in
the plasma become violent soundwaves which leads to spectacular ripples
in space and time, known as gravitational waves, that could be detected
over the next few decades. The beauty of looking for gravitational waves
is that the Universe is completely transparent to gravitational waves
all the way back to the beginning," said White.

The researchers also found the conditions to create these ripples are very common, and the resulting gravitational waves should be large enough,
and low enough frequency to be detected by conventional gravitational
wave detectors.

"If this is how the asymmetry was made, it is almost certain that we will
soon detect a signal from the beginning of time confirming this theory
on why we, and the rest of the world of matter, exist at all," said White.

Details of their study were published in Physical Review Letters on
October 27.

========================================================================== Story Source: Materials provided by Kavli_Institute_for_the_Physics_and_Mathematics_of_the Universe. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Graham White, Lauren Pearce, Daniel Vagie, Alexander
Kusenko. Detectable
Gravitational Wave Signals from Affleck-Dine Baryogenesis. Physical
Review Letters, 2021; 127 (18) DOI: 10.1103/PhysRevLett.127.181601 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211208110316.htm

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