Neutrino Mass Bounds from Onbb Decays and Large Scale Structures Yong-Yeon Keum National Taiwan University Dec. 4-7, 2007 OMEG07, Hokkaido Univ., Japan Collaborations with K. Ichiki and T. kajino

Primordial Neutrinos in Astrophysics The connection between cosmological observations and neutrino physics is one of the interesting and hot topic in astro-particle physics. Precision observations of the cosmic microwave background and large scale structure of galaxies can be used to prove neutrino mass with greater precision than current laboratory experiments.

Contents: Neutrinoless Double beta Decays and Total Neutrino Mass bounds Neutrino Mass bound from Large Scale Structures (CMB, Power Spectrum,…..) Discussion

Nature of Neutrinos: Dirac Particles: - anti-Particle is different from Particle; - L is conserved. Majorana Particles: - anti-Particle = Particle; - processes. The nature of neutrinos is directly related to the fundamental symmetries of elementary particle interactions. The relative smallness of nu-masses can naturally be explained by at a high scale:(Seesaw-Mechanism: Gell-Mann, Ramond, Slansky; Yanagida[1979], Mohapatra,Senjanovic[1980]) In this case, the massive neutrinos are Majorana particles nu-oscillations cannot distinguish between Dirac and Majorana particles: only processes can answer this question and the most sensitive one is (bb)on decay.

What we know right Now: neutrinos have mass (NuOsc-exp.) the rough magnitude of the leptonic mixing angles (two large and one relatively small angles) the masses of all three neutrino species are very small compared with charged fermions

What we don’t know: Are neutrinos their own anti-particles ? ( Dirac vs Majorana particles ) What is the absolute mass of neutrinos and their mass ordering, i.e. (normal, inverted or quasi-degenerate ?) Is there CP violation in the leptonic sector ?

Neutrino Mixing and Oscillation If neutrinos are massive, it is possible that the weak eigenstates are not the same as the mass eigenstates: PMNS (Pontecorvo-Maki-Nakagawa-Sakata) matrix (1957-1962)

Neutrino Mixing Matrix

Neutrinoless Double Beta Decays Part I

Neutrinoless double-beta decay (A,Z)  (A,Z+2) + e- + e- (DL=2) -- the most senstive process to the total lepton number and small majorana neutrino masses

0nbb-decay has not yet been seen experimentally. The best result has been achieved in the Heidelberg-Moscow (HM) 76Ge experiment: T01/2 > 1.9 x 1025 years  |mbb| < 0.55 eV Many future ambitious projects: CAMEO,CUORE,COBRA,EXO,GENIUS,MAJORANA, MOON,XMASS

Neutrioless Double-beta decay vs Neutrino Mass Mass Ordering (for simplicity) The rate of 0nbb decay depends on the mag. of the element of the neutrino mass matrix:

Sum of Neutrino masses Since the solar mass-squared difference is very small, it can be ignored; setting For the sum of neutrino masses :

Bound of the total neutrino mass Depends on two parameters; the scale of atm. Neutrino Osci, (D) the amplitude of solar Neutrino Osci. ( )

Total Nu-Mass vs Mee ( NH vs IH ) Inverse Hierarchy Normal Hierarchy Mee(eV)

Effective Majorana Nu-mass

Mee vs lightest m Normal Hierarchy Inverse Hierarchy

Neutrino Mass bound from Large Scale Structures (CMB, Power Spectrum,… Neutrino Mass bound from Large Scale Structures (CMB, Power Spectrum,…..) Part II

Neutrino free-stream : If rn is carried by free-moving relativistic particles, we can discriminate between massless vs massive ,and between free vs interacting neutrinos. Neutrino masses determine two-different things: 1) temperature at which neutrinos cease to be non-relativistic, which controls the length on which neutrinos travel reducing clustering. 2) the function of energy carried by neutrinos, which controls how much neutrinos can smooth inhomogeneities. In Standard cosmology:

CMB vs Nv

Within Standard Cosmology Model (LCDM)

Equation of State (EoS) W = p/r It is really difficult to find the origin of dark-energy with non-interacting dark-energy scenarios.

Interacting dark energy model Interacting Neutrino-Dark-Energy Model Interacting dark energy model Example At low energy, The condition of minimization of Vtot determines the physical neutrino mass. nv mv Scalar potential in vacuum

Background Equations: K. Ichiki and YYK:2007 Background Equations: Perturbation Equations: We consider the linear perturbation in the synchronous Gauge and the linear elements:

With full consideration of Kinetic term Varying Neutrino Mass With full consideration of Kinetic term V( f )=Vo exp[- lf ] Mn=0.9 eV Mn=0.3 eV

W_eff Mn=0.9 eV Mn=0.3 eV

Mn=0.9 eV

Mn=0.3eV

Power-spectrum (LSS) Mn=0.9 eV Mn=0.3 eV

Neutrino mass Bound: Mn < 0.87 eV @ 95 % C.L.

Discussions Neutrinoless double beta decays can provides very important properties of neutrinos: Dirac or majorana particles; neutino mass information; mass-hierarchy pattern. In conclusion, results of precision analysis of CMB and LSS data don’t follow only from data, but also can rely on theoretical assumptions. Prospects: Future measurements of gravitational lensing of CMB light and/or of photon generated by far galaxies should allow to direct measure the total density with great accuracy. In this way, it might be possible to see the cosmological effects of neutrino masses, and measure them with an error a few times smaller than the atmospheric mass scale. This could allow us to discriminate between normal and inverted neutrino mass hierarchy.

Cosmological weak lensing Arises from total matter clustering Note affected by galaxy bias uncertainty Well modeled based on simulations (current accuracy <10%, White & Vale 04) Tiny 1-2% level effect Intrinsic ellipticity per galaxy, ~30% Needs numerous number (10^8) of galaxies for the precise measurement past z=zs Large-scale structure z=zl present z=0

Thanks For your attention!

Backup Slides

Four most useful items for probing new physics: Now we enter the era of Precision Neutrino Measurement Science (PMNS era). What do we hope to learn and which information is likely to teach us more about new physics than others. Four most useful items for probing new physics: Search for neutrinoless double beta decays Determined the sign of atmospheric mass difference square (neutrino mass hierarchy) the magnitude of establish or refute the existence of sterile neutrinos.

Max and Min values of m For a given value of Mee; The minimum value of m with The maximum value of m with

Sensitivities of the future exps.

76Ge 100Mo

present neutrino number density: The role played by neutrinos: Tdec ~ few me  dominant e-/e+  photons Tg = 2.73 K Tv = 1.96 K = 0.17 meV present neutrino number density: Since Tv is smaller than the neutrino mass scale, CMB neutrinos are today mostly non-relativisitic: Present data: H=100 h km/s Mpc with h=0.7 Neutrino masses have a minor effect(not yet observed), so that it is convenient, in first approximation, to consider neutrinos as massless.

Uncertainties from Nuclear Matix Element Higher order terms of nucleon current suppresses the nuclear element by about 30 % for all nuclei The estimated uncertainty of Mon due to gA is around 20 % ( in general gA =1.25, but gA =1 in quenched value) The evaluation of the Nuclear Matrix element Mon is a complex task Two established method : Shell Model vs Quasiparticle Random Phase Approximation (QRPA)