SoylentNews

Glueballs are the Missing Frontier of the Standard Model

posted by CoolHand on Monday October 26 2015, @03:39PM   
from the these-glueballs-ain't-for-sniffin dept.

darkfeline writes:

http://arstechnica.com/science/2015/10/missing-glueballs-are-sticky-problem-for-particle-physics/

The discovery of the Higgs boson was rightfully heralded as a triumph of particle physics, one that brought completion to the Standard Model, the collection of theories that describes particles and their interactions. Lost in the excitement, however, was the fact that we're still missing a piece from the Standard Model—another type of particle that doesn't resemble any other we've yet seen.

The particle is a glueball, but its goofy name doesn't express how interesting it is. Glueballs are unique in that they don't contain any matter at all: they have no quarks or electrons or neutrinos. Instead, they are made entirely of gluons, which are the particles that bind quarks together inside protons, neutrons, and related objects.

Particle physicists are sure they exist, but everything else about them is complicated, to say the least. Like so many other exotic particles (including the Higgs), glueballs are very unstable, decaying quickly into other, less massive particles. We don't have any ideas about their masses, however, which is obviously kind of important to know if you want to find them. We also don't know exactly how they decay, making it hard to know exactly how we'll identify them in experiments.

If I may be so bold, what do fellow SNs think of modern particle physics, and do any of you have any crazy alternative non-particle-centric physical theories (for example, a model of reality that works using 7-dimensional strings as opposed to 1-dimensional strings from string theory?)

---

Original Submission

• Glueballs Glueballs (Score: 5, Informative) by stormwyrm on Monday October 26 2015, @06:36PM

  by stormwyrm (717) on Monday October 26 2015, @06:36PM (#254815) Journal

  Chances are CERN or Fermilab has already seen at least one somewhere, the only problem is that they couldn't be absolutely sure that they were actually seeing was a glueball. It should be possible in principle to calculate their properties solely from the equations of quantum chromodynamics that explain how the Strong Force operates and from there design particle accelerator experiments to create glueballs and a means to detect them when they are created. Given how the glueballs are supposed to be unstable that generally means that they'd need to predict into what other particles they are supposed to decay into and at what rates. The only problem is that the required computations are so difficult that physicists have to use a method known as lattice QCD to even have a hope of getting even an approximation since simpler techniques based on perturbation theory that worked very well for electromagnetics don't cut it for the strong force. These Lattice QCD simulations are so hard that they have been used as a benchmark for high-performance supercomputing, and even the best simulations can only produce numerical approximations. There is also a bit of uncertainty as to the values of some of the physical constants that go into the equations of QCD, and the many different ways of calculating the glueball's properties result in many different predictions for its behaviour. There was an article [soylentnews.org] here recently about a team of physicists who used a different approach, showing that an already known particle resonance event seems like it might actually be a glueball, by using a different technique.

  --
  Numquam ponenda est pluralitas sine necessitate.

  Starting Score:	1		point
  Moderation		+3
  Interesting=1, Informative=2, Total=3
  Extra 'Informative' Modifier		0
  Karma-Bonus Modifier		+1
  Total Score:		5

• Re:Glueballs (Score: 2, Interesting) by pTamok on Monday October 26 2015, @10:33PM

  by pTamok (3042) on Monday October 26 2015, @10:33PM (#254909)

  This review paper looks at possible glueball candidates in existing particle accelerator data:

  Wolfgang Ochs (2013). "The status of glueballs". Journal of Physics G 40 (4): 043001. arXiv:1301.5183. doi:10.1088/0954-3899/40/4/043001. http://arxiv.org/abs/1301.5183 [arxiv.org]

  It's not that there are no candidates, but so far none of the candidates have reached the necessary level of significance.

  There is also very recent news about a particular candidate: the f0(1710) meson

  http://www.livescience.com/52558-glueballs-potentially-found-lhc.html [livescience.com] which references http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.115.131601 [aps.org]
  Another report of the same item: http://www.gizmag.com/meson-f01710-glueball-particle/39866/ [gizmag.com]
  ...and another http://www.techtimes.com/articles/94845/20151013/glueball-particle-nuclear-force.htm [techtimes.com]

  Parent