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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-3478
DTSTART:20140923T200000Z
DTEND:20140923T210000Z
DTSTAMP:20260419T161751Z
LAST-MODIFIED:20140920T222539Z
LOCATION:5280 Chamberlin Hall
SUMMARY:The Goldstone Exception:  Spontaneously broken global symmetry
 \, i.e. the Goldstone theorem\, protects the Higgs from a Fine Tuning 
 (FT) Problem\, Theory Seminar (High Energy/Cosmology)\, Bryan Lynn\, U
 niversity College London and Case Western University
DESCRIPTION:More than four decades ago\, B.W. Lee and K. Symanzik prov
 ed that\, in the O(4) Gell-Mann Levy (GML) model with Partially Conser
 ved Axial-vector Currents (PCAC)\, global Ward Takahashi Identities (W
 TI) force all Ultra-Violet Quadratic Divergences (UVQD) into the renor
 malized pseudo Nambu-Goldstone-Boson (NGB) pion mass-squared. Tadpole 
 renormalization is un-necessary.<br>
\n<br>
\nWe prove (to all-orders 
 perturbations) that all UVQD\, together with all other relevant operat
 ors\, therefore vanish identically in GML’s spontaneous symmetry bro
 ken (SSB) Goldstone-mode\, where pions are true NGB (i.e. exactly mass
 less). A weak-scale Higgs mass is natural in SSB GML\, the Higgs mass 
 and vacuum expectation value (VEV) are stable against quantum correcti
 ons and not FT: SSB GML has no Higgs FT problem. Neither do the SSB O(
 4) Schwinger model (PCAC=0) or the Standard Model (SM).  No-Higgs-FT i
 s simply another (albeit unfamiliar) consequence of WTI and the Goldst
 one Theorem.<br>
\n<br>
\nA huge class of high-mass-scale (M_{Heavy}>>
 m_{Higgs}) extensions of GML\, Schwinger and SM also demonstrate natur
 alness\, no-FT and heavy particle decoupling. We display two examples:
  a heavy (M_S >> m_{Higgs}) real scalar field\; and a right-handed Typ
 e 1 See-Saw Majorana neutrino with M_R >> m_{Higgs}. We prove that for
  |q^2| << M_{Heavy}^2\, the heavy degrees of freedom contribute only i
 rrelevant and marginal operators. Phenomenological consequences includ
 e the renewed possibility of thermal lepto-genesis in the neutrino-MSM
 . It is also easy to construct no-Higgs-FT models with very high-scale
  SUSY breaking.<br>
\n<br>
\nWe conjecture that\, since classical Gene
 ral Relativity (GR) couples democratically to spin=0\, ½ and 1 quantu
 m particles\, GR+SM (and maybe certain quantum gravity theories) will 
 also retain naturalness\, avoiding FT problems. Absent a SM FT problem
 \, there should be no expectation that LHC14 will discover physics bey
 ond the SM which is unrelated to neutrino mixing\, the only known expe
 rimental failure of the SM.
URL:https://www.physics.wisc.edu/events/?id=3478
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