- #1
kodama
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Does Peter Woits solution Higgs naturalness problem work?
"http://www.math.columbia.edu/~woit/wordpress/?p=5667
Conventional wisdom in the particle theory for about 30 years has been that the Standard Model has a huge “hierarchy” or “naturalness” problem, the solution to which is supposed to appear at the LHC via SUSY or some other new BSM physics. With no SUSY or other BSM physics appearing at the LHC, this conventional wisdom is now moving towards claims that fundamental physics has been shown by the LHC to be “unnatural”, with parameters that are environmental, artifacts of our position in the multiverse generated by the anthropic landscape of string theory.
It seems to me that a much more logical conclusion to draw would be that the LHC has just shown that the hierarchy/naturalness argument was mistaken. I’ve never understood why people found it convincing, and have often argued about this here on the blog. From the “hierarchy” angle, the problem is why the ratio of the electroweak-breaking scale to the GUT or Planck scale is such a small number, but we don’t actually have any evidence for GUT physics or for quantum gravitational physics, so no good reason to be sure that such high scales are relevant to anything or the cause of a hierarchy problem. From the “naturalness” side, while the theory is renormalizable, one can worry about the sensitivity to high energies of its cutoff dependence, but it’s unclear to me why one should be that concerned about this. More worrisome is that the Higgs sector introduces most of the undetermined parameters of the SM, a much more serious defect of the standard theory
He starts off with:
is there a Higgs naturalness problem?
•For decades the HEP community has asserted that naturalness is the central issue
•Simply put, we have assumed that either EWSB is natural, in which case we need to explain why, or that it is fine-tuned, in which case we also need to explain why
•I will argue that this is a false dichotomy,and that LHC results are hinting at a third path
then explains the standard dogma about quadratic sensitivity to the cutoff. He argues that the solution to this problem lies in properly understanding the scaling behavior of the Higgs, following ideas that go back at least to W. Bardeen in 1995 (see here). The fact that the renormalization group flow of the quartic term in the Higgs potential takes it to zero at high energies is interpreted as a suggestion that the right UV boundary condition is that the Higgs potential vanish.."
so Woit's proposed solution to the hierarchy angle is that
1- there is no GUT scale, no GUT unification, no GUT superheavy particles for the Higgs to couple to, driving up its mass and
2- the Planck scale is irrelevant to the Higgs. QG is irrelevant to the Higgs sector
it's worth noting that the particle associated with gravity, the graviton is presumably massless like photon and gluon, and the higgs does not couple to them.
Higgs physics is sensitive to cut-off but there is no GUT or Planck scale that serves as a cut-off. The top quark is the heaviest particle the Higgs couples to.
Higgs mass of 126 GEV is the result of quantum interactions with only the particles, fermions and WZ bosons of the SM, and possibly dark matter and light weight particles.
Does Peter Woit solution work?
Suppose there are no super heavy particles above the EW scale, Planck scale gravity does not couple with Higgs, and other particles like dark matter are ultra-light, less than 1 uev, like hypothetical axions and ultralight scalars. Is Higgs stable at 126 gev? ie there are many more particles yet to be discovered, and do couple to the Higgs, but they are all ultralight, less than 1 uev. The top quark is the heaviest fundamental particle
"http://www.math.columbia.edu/~woit/wordpress/?p=5667
Conventional wisdom in the particle theory for about 30 years has been that the Standard Model has a huge “hierarchy” or “naturalness” problem, the solution to which is supposed to appear at the LHC via SUSY or some other new BSM physics. With no SUSY or other BSM physics appearing at the LHC, this conventional wisdom is now moving towards claims that fundamental physics has been shown by the LHC to be “unnatural”, with parameters that are environmental, artifacts of our position in the multiverse generated by the anthropic landscape of string theory.
It seems to me that a much more logical conclusion to draw would be that the LHC has just shown that the hierarchy/naturalness argument was mistaken. I’ve never understood why people found it convincing, and have often argued about this here on the blog. From the “hierarchy” angle, the problem is why the ratio of the electroweak-breaking scale to the GUT or Planck scale is such a small number, but we don’t actually have any evidence for GUT physics or for quantum gravitational physics, so no good reason to be sure that such high scales are relevant to anything or the cause of a hierarchy problem. From the “naturalness” side, while the theory is renormalizable, one can worry about the sensitivity to high energies of its cutoff dependence, but it’s unclear to me why one should be that concerned about this. More worrisome is that the Higgs sector introduces most of the undetermined parameters of the SM, a much more serious defect of the standard theory
He starts off with:
is there a Higgs naturalness problem?
•For decades the HEP community has asserted that naturalness is the central issue
•Simply put, we have assumed that either EWSB is natural, in which case we need to explain why, or that it is fine-tuned, in which case we also need to explain why
•I will argue that this is a false dichotomy,and that LHC results are hinting at a third path
then explains the standard dogma about quadratic sensitivity to the cutoff. He argues that the solution to this problem lies in properly understanding the scaling behavior of the Higgs, following ideas that go back at least to W. Bardeen in 1995 (see here). The fact that the renormalization group flow of the quartic term in the Higgs potential takes it to zero at high energies is interpreted as a suggestion that the right UV boundary condition is that the Higgs potential vanish.."
so Woit's proposed solution to the hierarchy angle is that
1- there is no GUT scale, no GUT unification, no GUT superheavy particles for the Higgs to couple to, driving up its mass and
2- the Planck scale is irrelevant to the Higgs. QG is irrelevant to the Higgs sector
it's worth noting that the particle associated with gravity, the graviton is presumably massless like photon and gluon, and the higgs does not couple to them.
Higgs physics is sensitive to cut-off but there is no GUT or Planck scale that serves as a cut-off. The top quark is the heaviest particle the Higgs couples to.
Higgs mass of 126 GEV is the result of quantum interactions with only the particles, fermions and WZ bosons of the SM, and possibly dark matter and light weight particles.
Does Peter Woit solution work?
Suppose there are no super heavy particles above the EW scale, Planck scale gravity does not couple with Higgs, and other particles like dark matter are ultra-light, less than 1 uev, like hypothetical axions and ultralight scalars. Is Higgs stable at 126 gev? ie there are many more particles yet to be discovered, and do couple to the Higgs, but they are all ultralight, less than 1 uev. The top quark is the heaviest fundamental particle