A particle accelerator experiment involving scientists from Osaka
University created an unusual and extremely unstable particle and calculated
its mass. This might help us learn more about the interior workings of
ultra-dense neutron stars.
The majority of particles are composed of mixtures of just six different
kinds of fundamental particles known as quarks, according to the Standard
Model of particle physics. However, there are still a lot of unanswered
questions, one of which is the unusual but transient Lambda resonance
(1405). Understanding its makeup could help researchers learn more about the
incredibly dense matter found in neutron stars. It was originally thought to
be a particular mix of the three quarks up, down, and odd.
Now, researchers from Osaka University were a member of a group that was
successful in creating (1405) for the first time by fusing a K-meson and a
proton and figuring out its complicated mass (mass and width). A odd quark
and an up antiquark are both components of the negatively charged particle
known as the K-meson.
There are two up quarks and one down quark in the much more common proton
that forms up the matter that we are accustomed to. The study demonstrated
that instead of being a three-quark excited state, (1405) is best understood
as a transiently bound state of the proton and the K-meson.
The team explains the experiment they conducted at the J-PARC accelerator
in a paper that was recently published in Physics Letters B. The objective
was a deuterium target, which contained one proton and one neutron in each
K-meson. A K-meson expelled the neutron in an effective reaction, merging
with the proton to create the intended result (1405). According to Kentaro
Inoue, one of the study's authors, "the creation of a bound state of a K-
meson and a proton was only feasible because the neutron carried away some
of the energy."
The fact that quark (1405) has a very low total mass despite having an odd
quark that is almost 40 times heavier than an up quark has baffled
scientists. By watching how the decay products behaved during the trial, the
study team was able to determine the complex mass of (1405) with
accuracy.
According to Shingo Kawasaki, another study author, "we anticipate that
success in this sort of research can lead to a more precise depiction of
ultra-high-density matter that resides in the center of a neutron star."
This study suggests that (1405) is an unusual state with a total of five
quarks—four quarks and one antiquark—and deviates from the normal
categorization, which categorizes particles as either having three quarks or
one quark and one antiquark.
This study may help us understand how the Universe first began to develop
soon after the Big Bang and what happens to matter when it is subjected to
pressures and concentrations that are significantly higher than those we
observe in everyday situations.
