E.A. Paschos

Baryogenesis from a lepton asymmetric universe

We demonstrate that CP-violation in the Majorana mass matrices of the heavy neutrinos can generate a CP-asymmetric universe. The subsequent decay of the Majorana particles generates a lepton number asymmetry. During the electroweak phase transition the lepton asymmetry is converted into a baryon asymmetry, which survives down to this time.

Baryogenesis through mixing of heavy Majorana neutrinos

Abstract A mechanism is presented in which the mixing of right-handed heavy Majorana neutrinos creates a CP-asymmetric universe. When these Majorana neutrinos subsequently decay more leptons than anti leptons are produced. Due to a resonance phenomenon the lepton asymmetry created by this new mechanism can exceed by a few orders of magnitude any lepton asymmetry originating from direct decays. The asymmetry is finally converted into a baryon asymmetry during the electroweak phase transition.

Neutrino interactions in oscillation experiments

We calculate the neutrino induced cross sections relevant for oscillation experiments, including the

A simple connection between neutrino oscillation and leptogenesis

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A proposal for solar axion detection via Bragg scattering

-lepton threshold for quasielastic, resonance and deep-inelastic scattering. In addition to threshold effects, we include nuclear corrections for heavy targets which are moderate for quasielastic and large for single pion production. The nuclear effects for deep-inelastic reactions are small. We present cross sections together with their nuclear corrections for various channels which are useful for interpreting the experimental results and for determining parameters of the neutrino sector. Finally, we calculate the

1 / N(c) corrections to the hadronic matrix elements of Q(6) and Q(8) in K ---> pi pi decays

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Analysis of epsilon-prime / epsilon in the 1 / N(c) expansion

-lepton event rates for the OPERA LBL experiment.

Leptogenesis in left-right symmetric theories

The usual see-saw formula is modied by the presence of two Higgs tripletsinleft-rightsymmetrictheories. Thecontributionfromtheleft-handedHiggs triplet to the see-saw formula can dominate over the conventional one when the neutrino Dirac mass matrix is identied with the charged lepton or down quark massmatrix. Inthiscaseananalyticcalculationoftheleptonasymmetry,generated by the decay ofthelightest right-handed Majorananeutrino, ispossible. Fortypical parameters, the out-of-equilibrium condition for the decay is automatically fullled. The baryon asymmetry has the correct order of magnitude, as long as the lightest mass eigenstate is not much lighter then 10 6 to 10 8 eV, depending on the solution ofthesolarneutrino problem. Asizablesignalinneutrinoless doublebetadecaycan beexpected,aslongasthesmallestmasseigenstateisnotmuchlighterthan10 3 eV and the Dirac mass matrix is identied with the charged lepton mass matrix.

Weak interactions in six- and eight-quark models

Abstract The paper suggests using Bragg scattering to search for solar axions or other bosons. The enhancement factor from constructive interference can be as large as ∼ 10 4 over the whole solar axion spectrum. The angular correlation of the axion-to-photon cross section can be utilized to focus the converted celestial axions by using a large surface antenna covered with a thin film (∼ μm) of single crystals. A few cases are discussed, and the potential importance of this interaction-mode in other crystalline radiation detectors is mentioned. Alternatively, existing experimental data with semiconductor or other thermal (cryogenic) detectors — not only in dark matter research — should be reevaluated. Experiments based on this proposal could measure a coupling constant at the level g aγγ =10 −8 GeV −1 or lower for an axion mass up to a few keV.

Analysis of

We calculate long-distance contributions to the amplitudes A(K^0 --> pi pi, I) induced by the gluon and the electroweak penguin operators Q_6 and Q_8, respectively. We use the 1/N_c expansion within the effective chiral lagrangian for pseudoscalar mesons. In addition, we adopt a modified prescription for the identification of meson momenta in the chiral loop corrections in order to achieve a consistent matching to the short-distance part. Our approach leads to an explicit classification of the loop diagrams into non-factorizable and factorizable, the scale dependence of the latter being absorbed in the low-energy coefficients of the effective theory. Along these lines we calculate the one-loop corrections to the O(p^0) term in the chiral expansion of both operators. In the numerical results, we obtain moderate corrections to B_6^(1/2) and a substantial reduction of B_8^(3/2).