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VERSION:2.0
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PRODID:UW-Madison-Physics-Events
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UID:UW-Physics-Event-3876
DTSTART:20151215T213000Z
DTEND:20151215T223000Z
DTSTAMP:20210117T072311Z
LAST-MODIFIED:20151214T135332Z
LOCATION:5280 Chamberlin
SUMMARY:Raymond Stora's last discovery: Hidden U(1)_Y symmetry and new
Ward-Takahashi identities in the Abelian Higgs model\, Theory Seminar
(High Energy/Cosmology)\, Bryan Lynn\, Visiting Professor
DESCRIPTION: The SSB AHM (the gauge theory of a scalar ϕ∝(H+iπ) an
d a transverse vector A) has a massless pseudo-scalar π in Lorenz gau
ge. Physical states have a conserved global current and Goldstone theo
rem (GT)\, but no global charge. π contains a Nambu-Goldstone boson (
NGB). Slavnov-Taylor identities force on-shell T-matrix elements to be
independent of anomaly-free gauge\, and global\, U(1) transformations
\, yielding towers of ϕ-sector Ward-Takahashi IDs (WTI)\, which sever
ely constrain the dynamics\, and the effective potential\, of external
ϕ. Ultraviolet quadratic divergences (UVQD) contribute only to the p
seudo-NGB mass\, forced by the GT to 0 in the SSB mode\, so all UVQD v
anish. Weak-scale renormalized gauge-independent Higgs pole-mass and V
EV are therefore not technical-fine-tuned. The NGB is "eaten" and deco
uples as usual\, hiding the U(1) WTI from observable particle physics.
Our regularization-scheme-independent all-loop-orders results are unc
hanged by the addition of certain heavy matter fields\, as the WTI and
GT cause all relevant operators to vanish. We prove 5 new SSB decoupl
ing theorems\, illustrating them with two examples: a Heavy (>>Weak) Z
2-symmetric singlet real scalar field with 0 VEV\; and a heavy singlet
right-handed type 1 see-saw Majorana neutrino. Including all loops we
prove that these\, and certain other heavy degrees of freedom\, decou
ple from the low-energy effective Lagrangian\, contributing only irrel
evant operators. The NGB again decouples\, but our hidden SSB U(1) WTI
\, and the resultant NGB shift symmetry\, protect the low-energy SSB A
HM physics from loop contributions of heavy particles! Gauge-independe
nt observable weak-scale Higgs pole mass and VEV are not technical
-fine-tuned.
URL:https://www.physics.wisc.edu/events/?id=3876
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