eV seesaw with four generations

Abstract

We extend the eV seesaw scenario to four lepton generations. The LSND anomaly is taken as the right-handed seesaw scale, i.e. mR ∼ eV. The fourth generation then gives a heavy pseudo-Dirac neutrino which largely decouples from other generations, and is relatively stable. One effectively has a 3 + 3 solution to the LSND anomaly, where we illustrate with numerical solutions. Our study seems to indicate that the third mixing angle sin 2 θ13 may be less than 0.01.

Simultaneous extraction of the Fermi constant and PMNS matrix elements in the presence of a fourth generation

“…The possible role of a fourth generation in explaining some interesting hints for deviations from the Standard Model (SM) in flavour physics has been discussed in several papers [1][2][3][4][5][6][7][8][9]. The electroweak precision fit with respect to a fourth generation has been reconsidered as well [10][11][12].…”

AN UPDATED NUMERICAL ANALYSIS OF eV SEESAW WITH FOUR GENERATIONS

“…[6], and require m 2 41 ∼ 1 eV 2 , a total of 7 inputs. After minimizing the χ 2 , we obtain the values for the 12 parameters r i j , i and s i [3] of the model at the best fit point, and find Finally, we study CP violation by introducing CPV phase δ to leptonic mixing matrix and find that introducing δ leads to the relative improvement of the fit of χ 2 min,2009 − χ 2 min,CP = 0.007. Thus, the quality of the global fit does not improve much by introducing δ .…”

“…The LSND result of P(ν µ →ν e ) = 0.264% [1] can be explained if 1 sterile neutrino with m 2 ∼ 1eV 2 exists. In 2006, Hou and Soddu extended the so-called "eV seesaw" scenario [2], where the righthanded neutrino Majorana scale M R is of eV order, to four lepton generations [3]. The fourth generation gives a heavy pseudo-Dirac neutral lepton, which largely decouples from the other generations, and is relatively stable.…”

Updated Numerical Analysis of eV Seesaw with Four Generations

“…[6], and require m 2 41 ∼ 1 eV 2 , a total of 7 inputs. After minimizing the χ 2 , we obtain the values for the 12 parameters r i j , i and s i [3] of the model at the best fit point, and find where χ 2 min,2006 is the χ 2 minimum for best fit values in 2006, and χ 2 min,2009 is the χ 2 minimum for best fit values we get now. We conclude that agreement between eV Seesaw with 4 generations scenario and experimental data seems to improve slightly.…”

“…The LSND result of P(ν µ →ν e ) = 0.264% [1] can be explained if 1 sterile neutrino with m 2 ∼ 1eV 2 exists. In 2006, Hou and Soddu extended the so-called "eV seesaw" scenario [2], where the righthanded neutrino Majorana scale M R is of eV order, to four lepton generations [3]. The fourth generation gives a heavy pseudo-Dirac neutral lepton, which largely decouples from the other generations, and is relatively stable.…”