Study of the Λb→N∗ℓ+ℓ−\Lambda_{b} \to N^\ast \ell^+ \ell^- decay in light cone sum rules

The form factors of the $\Lambda_{b} \to N^\ast \ell^+ \ell^-$ decay are calculated in the framework of the light cone QCD sum rules. In the calculations the contribution of the negative parity $\Lambda_b^\ast$ baryon is eliminated by constructing the sum rules for different Lorentz structures. Furthermore the branching ratio of the semileptonic $\Lambda_b \to N^\ast \ell^+ \ell^-$ decay is calculated. The numerical study for the branching ratio of the $\Lambda_{b} \to N^\ast \ell^+ \ell^-$ decay indicates that it is quite large and could be measurable at future planned experiments to be conducted at LHCb.Comment: 21 pages, 2 figures, LaTeX formatte

Radiative decays of the p-wave charmed heavy baryons

The radiative decays of the p-wave charmed heavy baryons to the ground state baryon states are studied in the framework of the light cone QCD sum rules method. Firstly, the transition form factors that describe these transitions are estimated, and then using these form factors the corresponding decay widths are calculated. A comparison of our results on the decay widths with those predicted by the other approaches existing in literature is performed

Global structure of thermal tides in the upper cloud layer of Venus revealed by LIR onboard Akatsuki

Longwave Infrared Camera (LIR) onboard Akatsuki first revealed the global structure of the thermal tides in the upper cloud layer of Venus. The data were acquired over three Venusian years, and the analysis was done over the areas from the equator to the mid-latitudes in both hemispheres and over the whole local time. Thermal tides at two vertical levels were analyzed by comparing data at two different emission angles. Dynamical wave modes consisting of tides were identified; the diurnal tide consisted mainly of Rossby-wave and gravity-wave modes, while the semidiurnal tide predominantly consisted of a gravity-wave mode. The revealed vertical structures were roughly consistent with the above wave modes, but some discrepancy remained if the waves were supposed to be monochromatic. In turn, the heating profile that excites the tidal waves can be constrained to match this discrepancy, which would greatly advance the understanding of the Venusian atmosphere.Comment: 27 pages, 8 figure

The masses and residues of doubly heavy spin--3/2 baryons

The masses and residues of the spin--3/2 doubly heavy baryons are calculated within the QCD sum rules method. A comparison of our predictions with those existing in the literature is also made.Comment: 11 Pages and 4 Table

Phononic thermal conductivity in silicene: the role of vacancy defects and boundary scattering

We calculate the thermal conductivity of free-standing silicene using the phonon Boltzmann transport equation within the relaxation time approximation. In this calculation, we investigate the effects of sample size and different scattering mechanisms such as phonon-phonon, phonon-boundary, phonon-isotope and phonon-vacancy defect. Moreover, the role of different phonon modes is examined. We show that, in contrast to graphene, the dominant contribution to the thermal conductivity of silicene originates from the in-plane acoustic branches, which is about 70\% at room temperature and this contribution becomes larger by considering vacancy defects. Our results indicate that while the thermal conductivity of silicene is significantly suppressed by the vacancy defects, the effect of isotopes on the phononic transport is small. Our calculations demonstrate that by removing only one of every 400 silicon atoms, a substantial reduction of about 58\% in thermal conductivity is achieved. Furthermore, we find that the phonon-boundary scattering is important in defectless and small-size silicene samples, specially at low temperatures.Comment: 9 pages, 11 figure

Tenth-order lepton g-2: Contribution of some fourth-order radiative corrections to the sixth-order g-2 containing light-by-light-scattering subdiagrams

This paper reports the tenth-order QED contribution to lepton g-2 from diagrams of three gauge-invariant sets VI(d), VI(g), and VI(h), which are obtained by including various fourth-order radiative corrections to the sixth-order g-2 containing light-by-light-scattering subdiagrams. In the case of electron g-2, they consist of 492, 480, and 630 vertex Feynman diagrams, respectively. The results of numerical integration, including mass-dependent terms containing muon loops, are 1.8418(95) (alpha/pi)^5 for the Set VI(d), -1.5918(65) (alpha/pi)^5 for the Set VI(g), and 0.1797(40) (alpha/pi)^5 for the Set VI(h), respectively. We also report the contributions to the muon g-2, which derive from diagrams containing an electron, muon or tau lepton loop: Their sums are -5.876(802) (alpha/pi)^5 for the Set VI(d), 5.710(490) (alpha/pi)^5 for the Set VI(g), and -8.361(232) (alpha/pi)^5 for the Set VI(h), respectively.Comment: 17 pages, 5 figure

Magnetic dipole moments of the heavy tensor mesons in QCD

The magnetic dipole moments of the ${\cal D}_2$, and ${\cal D}_{S_2}$, ${\cal B}_2$, and ${\cal B}_{S_2}$ heavy tensor mesons are estimated in framework of the light cone QCD sum rules. It is observed that the magnetic dipole moments for the charged mesons are larger than that of its neutral counterpart. It is found that the $SU(3)$ flavor symmetry violation is about 10\% in both $b$ and $c$ sectors.Comment: 16 pages, 6 figures, LaTeX formatte

Formation of the binary pulsars PSR B2303+46 and PSR J1141-6545 - young neutron stars with old white dwarf companions

We have investigated the formation of the binary radio pulsars PSR B2303+46 and PSR J1141-6545 via Monte Carlo simulations of a large number of interacting stars in binary systems. PSR B2303+46 has recently been shown (van Kerkwijk & Kulkarni 1999) to be the first neutron star - white dwarf binary system observed, in which the neutron star was born after the formation of the white dwarf. We discuss the formation process for such a system and are able to put constraints on the parameters of the initial ZAMS binary. We present statistical evidence in favor of a white dwarf companion to the binary pulsar PSR J1141-6545, just recently discovered in the Parkes Multibeam Survey. If this is confirmed by observations this system will be the second one known in which the neutron star was born after its white dwarf companion. We also predict a minimum space velocity of 150 km/s for PSR J1141-6545, and show it must have experienced an asymmetric SN in order to explain its low eccentricity. Finally, we estimate the birthrate of these systems relative to other binary pulsar systems and present the expected distribution of their orbital periods, eccentricities and velocities.Comment: 9 pages, 4 figures, 2 tables, some revisions, accepted for publication in A&A Main Journa