Majorana Neutrinos and Same-Sign Dilepton Production at LHC and in Rare Meson Decays

We discuss same-sign dilepton production mediated by Majorana neutrinos in high-energy proton-proton collisions pp\ra \ell^+ \ell^{\prime +}X for $\ell,~ \ell^\prime = e,~ \mu,~ \tau$ at the LHC energy $\sqrt{s}=14$ TeV, and in the rare decays of $K$, $D$, $D_s$, and $B$ mesons of the type M^{+}\ra M^{\prime -}\ell ^{+}\ell ^{\prime+}. For the $pp$ reaction, assuming one heavy Majorana neutrino of mass $m_N$, we present discovery limits in the $(m_{N},|U_{\ell N}U_{\ell^\prime N}|)$ plane where $U_{\ell N}$ are the mixing parameters. Taking into account the present limits from low energy experiments, we show that at LHC for the nominal luminosity L=100 fb$^{-1}$ there is no room for observable same-sign dilepton signals. However, increasing the integrated luminosity by a factor 30, one will have sensitivity to heavy Majorana neutrinos up to a mass $m_N\leq 1.5$ TeV only in the dilepton channels $\mu\mu$ and $\mu \tau$, but other dilepton states will not be detectable due to the already existing strong constraints. We work out a large number of rare meson decays, both for the light and heavy Majorana neutrino scenarios, and argue that the present experimental bounds on the branching ratios are too weak to set reasonable limits on the effective Majorana masses.Comment: 18 pages, 4 figures (requires graphicx), a coefficient in Eq. (4) corrected leading to drastic reduction in the Majorana-induced same-sign dilepton cross-section at LHC; revised Figs. 2 and 3; references adde

Homogenization of the planar waveguide with frequently alternating boundary conditions

We consider Laplacian in a planar strip with Dirichlet boundary condition on the upper boundary and with frequent alternation boundary condition on the lower boundary. The alternation is introduced by the periodic partition of the boundary into small segments on which Dirichlet and Neumann conditions are imposed in turns. We show that under the certain condition the homogenized operator is the Dirichlet Laplacian and prove the uniform resolvent convergence. The spectrum of the perturbed operator consists of its essential part only and has a band structure. We construct the leading terms of the asymptotic expansions for the first band functions. We also construct the complete asymptotic expansion for the bottom of the spectrum

Spinors for Spinning p-Branes

The group of the p-brane world volume preserving diffeomorphism is considered. The infinite-dimensional spinors of this group are related, by the nonlinear realization techniques, to the corresponding spinors of its linear subgroup, that are constructed explicitly. An algebraic construction of the Virasoro and Neveu-Schwarz-Ramond algebras, based on this infinite-dimensional spinors and tensors, is demonstrated.Comment: 18 page

In Escherichia coli ammonia inhibits cytochrome bo3 but activates cytochrome bd-I

Interaction of two redox enzymes of Escherichia coli, cytochrome bo3 and cytochrome bd-I, with ammonium sulfate/ammonia at pH 7.0 and 8.3 was studied using high-resolution respirometry and absorption spectroscopy. At pH 7.0, the oxygen reductase activity of none of the enzymes is affected by the ligand. At pH 8.3, cytochrome bo3 is inhibited by the ligand, with 40% maximum inhibition at 100 mM (NH4 )2SO4 . In contrast, the activity of cytochrome bd-I at pH 8.3 increases with increasing the ligand concentration, the largest increase (140%) is observed at 100 mM (NH4 )2SO4 . In both cases, the effector molecule is apparently not NH4+ but NH3 . The ligand induces changes in absorption spectra of both oxidized cytochromes at pH 8.3. The magnitude of these changes increases as ammonia concentration is increased, yielding apparent dissociation constants Kdapp of 24.3 ± 2.7 mM (NH4 )2SO4 (4.9 ± 0.5 mM NH3 ) for the Soret region in cytochrome bo3, and 35.9 ± 7.1 and 24.6 ± 12.4 mM (NH4 )2SO4 (7.2 ± 1.4 and 4.9 ± 2.5 mM NH3 ) for the Soret and visible regions, respectively, in cytochrome bd-I. Consistently, addition of (NH4)2SO4 to cells of the E. coli mutant containing cytochrome bd-I as the only terminal oxidase at pH 8.3 accelerates the O2 consumption rate, the highest one (140%) being at 27 mM (NH4 )2SO4 . We discuss possible molecular mechanisms and physiological significance of modulation of the enzymatic activities by ammonia present at high concentration in the intestines, a niche occupied by E. coli

Exchange-assisted tunneling in the classical limit

The exchange interaction and correlations may produce a power-law decay instead of the usual exponential decrease of the wave function under potential barrier. The exchange-assisted tunneling vanishes in the classical limit, however, the dependence on the Planck constant h is different from that for a conventional single-particle tunneling

Discrete symmetry's chains and links between integrable equations

The discrete symmetry's dressing chains of the nonlinear Schrodinger equation (NLS) and Davey-Stewartson equations (DS) are consider. The modified NLS (mNLS) equation and the modified DS (mDS) equations are obtained. The explicitly reversible Backlund auto-transformations for the mNLS and mDS equations are constructed. We demonstrate discrete symmetry's conjugate chains of the KP and DS models. The two-dimensional generalization of the P4 equation are obtained.Comment: 20 page