THE CONNECTION BETWEEN NEUTRINO EXPERIMENTS AND LEPTOGENESIS

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THE CONNECTION BETWEEN NEUTRINO EXPERIMENTS AND
LEPTOGENESIS
Alicia Broncano Berrocal MPI
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Cosmological Baryon Asymmetry
Data from the sun and cosmic rays
We study the low energy implications of seesaw
model and analize what information could
they provide about the full theory
LEPTOGENESIS (Fukugita,Yanagida,1986)

SEESAW MODEL (Minkowski, 1977 Gell-Mann, Ramond,
Slansky, 1979)
Non-zero Neutrino Masses and Mixings !
First evidence of physics beyond the SM mn 0 in
the minimal SM by B-L accidental symmetry.
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Mass Lagrangian
It can be integrated out and obtain
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SEESAW MECHANISM
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The seesaw contains the fundamental
ingredients the cosmological baryon asymmetry

• Baryogenesis requires physics beyond the SM with
• New sources of CP dCKM phase too small
• B-L at T gt TEW 100 GeV,

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The dependence of leptogenesis on
and allows to relate it to neutrino seesaw masses.
( DavidsonIbarra,2002 Pilaftsis et.al, 2003
Giudice et.al, 2003 Buchmüller et.al.,2004...)
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Count the number of physical parameters in the
leptonic mass Lagrangians
(Santamaria,1993)
NOT ENOUGH LOW-ENERGY MEASUREMENTS
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Is there a model independent way to recover the
seesaw parameters ?
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THE SEESAW EFFECTIVE LAGRANGIAN
As , is integrated out
Seesaw effective Lagrangian
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term
(AB,Gavela,Jenkins,2002)
Conserves L
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Lagrangian in canonical form and in mass basis
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Non-unitary mixing matrix
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In 2x2 scenario
Which could appear, for instance, in
8 moduli 2 phases
The same as in the full theory
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By considering , we recover
the same number of parameters as in the original
theory
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Depends on both
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Leptogenesis CP-asymmetry
(AB,Gavela,Jenkins,2003)

• Complicated function, but it exists
• Lepto CP-phase depends on all low-energy phases
• For instance,

(No Dirac or Majorana phases)
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Limiting cases

• eigenvalues degenerate

• if

• if
• ??? if

(Davidson Ibarra,2002)
(Hambye et al,2004)
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Observational problem
Even lowering the seesaw scale at TeV

• Very far from present bounds
• Flavor Universality
• Rare decays
• Neutrino oscillations

(Bergmann Kagan, 1999)
(Bernabeu et al, 1996)
(NOMAD)
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• SEESAW BASED ALTERNATIVES
• Assume other models of new physics which
• Decrease the number of parameters
• GUT ( Branco et. al., 2002 Allbright
  Barr,2004)
• Flavor symmetries (Frampton et. al, 2002 Xing
  2002..)
• Provide other observables
• SUSY (Casas Ibarra, 2001 Davidson
  Ibarra,2002)

Minimal effective Lagrangian generic for all
models
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A possible symmetry between quarks and leptons,
is not evident when comparing

• Could they be similar at some high scale and have
  changed through renormalization effects ?
• Weak int. dominate lepton RGE flavor mixing
• Strong int. dominate quarks RGE no flavor
  mixing

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• Evolution of the leptonic mixing matrix
  calculated from the RGE of to
  

• Two generations and no CP-violation

(Babu et.al,1993 Casas et.al,2000 Antusch
et.al,2003,)

• Evolution of the leptonic mixing matrix
  calculated in the full seesaw theory has also
  terms of the type

(Pilaftsis,Kniehl,2002)
in effective theory
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The connection with the RGE of the leptonic
mixing in the full seesaw should consider the
dominant flavor changing terms in
the effective theory
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m M
Renormalization Group evolution
m100 GeV
d6 operators generated by radiative mixing (
does not mix)
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Non diagonal matrix in flavor space
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Necessary to define the one loop matrix
From me diagonalization
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Two generations and no CP-violation
(AB,Gavela,Jenkins,2004)
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OVERLOOK
Generic relationship between low-energy
quantities and seesaw model and leptogenesis
from
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LEPTOGENESIS
SEESAW MODEL
Basic ingredients

• Leptonic d measured CP-violation
• 2b0n-decay detected B-L violation