BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:U(n) Spectral Covers from Decomposition - Hayashi\, H (Korea Insti
 tute for Advanced Study (KIAS))
DTSTART:20120628T161500Z
DTEND:20120628T163000Z
UID:TALK38737@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:We construct decomposed spectral covers for bundles on ellipti
 cally fibered Calabi-Yau threefolds whose structure groups are S(U(1) x U(
 4))\, S(U(2) x U(3)) and S(U(1) x U(1) x U(3)) in heterotic string compact
 ifications. The decomposition requires not only the tuning of the SU(5) sp
 ectral covers but also the tuning of the complex structure moduli of the C
 alabi-Yau threefolds. This configuration is translated to geometric data o
 n F-theory side. We find that the monodromy locus for two-cycles in K3 fib
 ered Calabi-Yau fourfolds in a stable degeneration limit is globally facto
 rized with squared factors under the decomposition conditions. This signal
 s that the monodromy group is reduced and there is a U(1) symmetry in a lo
 w energy effective field theory. To support that\, we explicitly check the
  reduction of a monodromy group in a slice of the moduli space for an E6 g
 auge theory with (1+2) decomposition. This may provide a systematic way fo
 r constructing some F-theory models with U (1) symmetries.\n
LOCATION:Seminar Room 1\, Newton Institute
END:VEVENT
END:VCALENDAR