At the Relativistic Heavy Ion Collider (RHIC), a U.S. Department of Energy (DOE) Office of Science user facility for nuclear physics research located at DOE’s Brookhaven National Laboratory, physicists are analyzing data from gold ion smashups for evidence of a so-called critical point in the transition of nuclear matter from one phase to another.
New discoveries from individuals from RHIC’s STAR Joint effort distributed in Actual Survey Letters hint that computations anticipating the number of lightweight cores that ought to rise up out of crashes could assist with denoting that spot on the guide of atomic stage changes. To answer fundamental questions about the composition of our universe, proof of a critical point—a point at which nuclear matter changes from one phase to another—is essential.
Xiaofeng Luo, a member of the RHIC’s STAR Collaboration from Central China Normal University (CCNU) who led a group of students in this analysis, stated, “You can imagine the nuclear phase diagram as a bridge connecting the past—the Big Bang and the early universe—to visible matter as we know it today and even neutron stars.” It is crucial for scientific research as well as human comprehension of our origins.”
“It is crucial for science and for our understanding of where we came from as a species. You can think of the nuclear phase diagram as a bridge connecting the past—the Big Bang and the early universe—to visible matter as we know it today, and even neutron stars.”
Xiaofeng Luo, a member of RHIC’s STAR Collaboration from Central China Normal University (CCNU).
The collisions of the Critical Point Search Party (RHIC) recreate a hot, dense state of matter that existed for a brief moment 14 billion years after the Big Bang. A soup of “free” quarks and gluons—the building blocks of protons and neutrons in atomic nuclei—makes up this matter, which is referred to as a quark-gluon plasma (QGP). RHIC physicists can examine how this primordial soup is created and transformed back into ordinary nuclear matter by colliding heavy ions at various energies.
To search for indications of a basic point — where the kind of progress from QGP to conventional matter changes from a smooth hybrid (where two stages coincide, as when margarine bit by bit liquefies on a warm day) to an unexpected shift (like water out of nowhere bubbling)—the researchers search for variances in things they measure emerging from the impacts.
A past report found tempting indications of the sort of changes researchers would expect around the basic point by taking a gander at the quantity of net protons created at the different impact energies. As the QGP cools, protons, each composed of three quarks, form. Protons can be used to represent the overall baryon density—baryons are all particles composed of three quarks, including neutrons.
Researchers expect that as the baryon thickness of the issue expands, it’s almost certain these protons and neutrons will blend, or meet up, to frame lightweight cores when the QGP “freezes out.” As a result, they attempted to track the yield of a particular kind of light nucleus known as a triton, which is composed of one proton and two neutrons. They might be able to pinpoint the crucial point by observing patterns of fluctuation in the production of tritons.
During phase one of the Beam Energy Scan (BES-I), the data were gathered by the Solenoidal Tracker at RHIC, a particle detector known as STAR, just like in the previous study. This program recorded depictions of impacts at different energies and temperatures from 2010 to 2017, catching changes in the numbers and sorts of particles spilling out. This new analysis builds on a 2017 paper by Brookhaven physicist Zhangbu Xu and colleagues that predicted that the critical point should be linked to the yield ratio of light nuclei like tritons.
Dingwei Zhang, a member of the RHIC’s STAR Collaboration and Ph.D. student at CCNU, stated, “The formation of these light nuclei requires a certain baryon density.” On the off chance that the framework is moving toward the basic point, the baryon thickness varies a great deal. As a result, we wanted to see if this analysis revealed any fluctuations and thus identified the critical point.
The STAR detector ought to be sensitive to a critical point when it comes to following changes in the yield ratio of lightweight nuclei like deuterons and tritons that emerge from collisions. The data (red points) mostly match the predictions (shaded areas), but two outlying points may be indications of the kinds of fluctuations that scientists anticipate occurring around the critical point. Credit: Brookhaven National Laboratory Theorists’ models of how new nuclei would form when protons and neutrons coalesced matched the data at most of the analyzed collision energies. Yet, at two places — from impacts at 19.6 billion political decision volts (GeV) and 27 GeV — the information leaped out of the gauge anticipated by the model, indicating those sought-after changes.
The points have a combined significance that is still below the level needed to claim a discovery in physics.
According to Luo, “We hoped this analysis would be sensitive to the critical point.” It is certainly encouraging to see these outliers here, which makes us very happy. All of these observables ought to eventually give a consistent signal if the critical point exists in the energy range we covered.
The results of the analysis of a plethora of additional collision data will be eagerly anticipated by researchers. In 2021, the STAR coordinated effort effectively finished the second period of the Shaft Energy Output (BES II), which caught gold smashup previews at different RHIC energies, including the most reduced energy of 3 GeV.
“We trust that the BES II information will assist us with improving the aversion to a basic point signal,” Luo said. “With higher insights, we might have the option to arrive at the degree of importance expected to guarantee a revelation. What’s more, that sounds enormous.”
More information: M. I. Abdulhamid et al, Beam Energy Dependence of Triton Production and Yield Ratio ( Nt×Np/Nd2 ) in Au+Au Collisions at RHIC, Physical Review Letters (2023). DOI: 10.1103/PhysRevLett.130.202301
