There are tens of unsolved basic problems in particle physics and cosmology.
There was published article entitled “Unifying inflation with the axion, dark matter, baryogenesis and the seesaw mechanism” by G.Ballesteros, et al. (21 February 2017). Authors try to solve five from the tens unsolved basic problems by introducing 6 new particles. We can read the arxiv original paper
https://arxiv.org/abs/1608.05414
published also in The Physical Review Letters, or the popular science article entitled “Group introduces six new particles to standard model (SM) to solve five enduring problems”
https://phys.org/news/2017-02-group-particles-standard-problems.html
The main conclusion is that we need 6 new particles to explain dark matter, to solve the strong CP problem, explain the origin of the small SM neutrino masses, the matter-antimatter asymmetry via thermal leptogenesis, and a stabilization of the effective SM potential at high energies due to a threshold mechanism.
First we can list the SM particles - in parenthesis is number of particles when we take into account antiparticles and the SM “colors”:
Quarks 6 (36)
Leptons 6 (12)
Carriers of strong interactions:
--Gluons 1 (8)
Carriers of weak interactions:
--W bosons 1 (2)
--Z bosons 1 (1)
Carriers of electromagnetic interactions:
--Photons 1 (1)
Higgs boson 1 (1)
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Total number: 17 (61)
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Authors of the paper propose 6 (14) new particles but it is not an end because there are the other unsolved basic problems! The new particles are as follows.
1) A vector-like color triplet fermion Q. The Dirac fermion Q can be split in two Weyl fermions with charges -1/3 and 1/3 so it looks as additional quark 1 (6). It solves the problem of overabundance of unwanted particles.
2) Primordial inflation is driven by two, not one, singlet scalar fields so there appears the modulus of the new singlet that leads to new particle rho 1 (1). The additional scalar field causes that the Higgs field does not move into instability region of the potential - such instability causes that the present electroweak vacuum is invalid.
3) The spin-0 axion: 1 (1), to explain dark matter.
4) Three right-handed heavy SM-singlet neutrinos 3 (6).
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Total number of new particles: 6 (14)
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Can you see the “method”? To explain new problems, there appear new free parameters, new free parameters, new free parameters….. Moreover, presented theory is very speculative.
This is not a serious physics! To the 17 + 6 = 23 (61 + 14 = 75) particles we must add next particles to solve the next basic problems and about 20 coupling constants describing interactions. What physical mechanisms quantized them? Why in SM appear free parameters as well? Why SM is such messy theory? And, first of all, why within SM we cannot calculate the half-integral spin of nucleons? Applying more and more parameters and functions taken from “ceiling” (i.e. without physical origin), we can explain everything and fit theoretical results to experimental data.
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On the other hand, in the Scale-Symmetric Theory (SST) all fields and particles are composed of free and bound non-gravitating tachyons i.e. in SST there is only one initial “particle”/piece-of-space. SST starts from 7 parameters only (and there do not appear free parameters) and a few new symmetries.