SN 2008fv: the third type Ia supernova in NGC 3147

Multiple outbursts of type Ia SNe in one galaxy present a unique opportunity to study the homogeneity of these objects. NGC 3147 is only the second known galaxy with three SNe Ia, another one is NGC 1316. We present CCD UBVRI photometry for SN Ia 2008fv and compare the light and color curves of this object with those for SNe Ia discovered earlier in NGC 3147: 1972H and 1997bq. The photometric properties of SNe 1997bq and 2008fv are nearly identical, while SN 1972H exhibits faster declining light curve.Comment: 11 pages, 6 figures, submitted to Peremennye Zvezdy (Variable Stars

On the Coulomb corrections to the total cross section of the interaction of the π+π−\pi^+\pi^- atom with ordinary atoms at high energy

The size of $\pi^+\pi^-$ atom in the low lying states is considerably smaller than the radius of atomic screening. Due to that we can neglect this screening calculating the contribution of multi-photon exchanges. We obtain the analytic formula for Coulomb corrections which works with a very good accuracy for the ground state of $\pi^+\pi^-$ atom.Comment: 9 pages, LATEX with 1 Postscript figur

Superconductivity of electron-hole pairs in a bilayer graphene system in a quantizing magnetic field

The state with a spontaneous interlayer phase coherence in a graphene based bilayer quantum Hall system is studied. This state can be considered as a gas of superfluid electron-hole pairs with the components of the pair belonging to different layers. Superfluid flux of such pairs is equivalent to two electrical supercurrents in the layers. It is shown that the state with the interlayer phase coherence emerges in the graphene system if a certain imbalance of the Landau level filling factors of the layers is created. We obtain the temperature of transition into the superfluid state, the maximum interlayer distance at which the phase coherence is possible, and the critical values of the supercurrent. The advantages of use of graphene systems instead of GaAs heterostructures for the realization of the bilayer electron-hole superconductivity is discussed.Comment: 16 pages, 8 figure

Influence of Cooper pairing on the inelastic processes in a gas of Fermi atoms

Correlation properties in ultracold Fermi gas with negative scattering length and its impact on the three-body recombination is analyzed. We find that Cooper pairing enhances the recombination rate in contrast to the decrease of this rate accompanying Bose-Einstein condensation in a Bose gas. This trend is characteristic for all interval of temperatures T<Tc