corrections to form factors of D-meson semileptonic decays

Ivanov, A. N.; Troitskaya, N. I.

doi:10.1016/s0370-2693(96)01666-8

Cited by 33 publications

(70 citation statements)

References 24 publications

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“…2. The warp has an oscillatory behaviour, as found by Ivanov & Illarionov (1997), with the wavelength increasing with radius, consistent with the local dispersion relation. This non-monotonic behaviour of the inclination contrasts with the Bardeen-Petterson effect (Bardeen & Petterson 1975), which was derived using an incorrect equation for the warp.…”

Section: Variation Of Disc Tilt With Radiussupporting

confidence: 81%

“…Depending on the 'amount of viscosity', the induced warps can propagate either diffusively, roughly speaking if the Shakura & Sunyaev (1973) viscosity parameter α is greater than H/r, or in a wave-like manner if α is smaller than H/r. Ivanov & Illarionov (1997) showed that the warp has an oscillatory radial structure in a low-viscosity disc, and this was investigated further by Lubow, Ogilvie & Pringle (2002).…”

Section: Warped Discsmentioning

confidence: 92%

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On an excitation mechanism for trapped inertial waves in discs around black holes

Ferreira

Ogilvie

2008

Monthly Notices RAS

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According to one model, high‐frequency quasi‐periodic oscillations (QPOs) can be identified with inertial waves, trapped in the inner regions of accretion discs around black holes due to relativistic effects. In order to be detected, their amplitudes need to reach large enough values via some excitation mechanism. We work out in detail a non‐linear coupling mechanism suggested by Kato, in which a global warping or eccentricity of the disc has a fundamental role. These large‐scale deformations combine with trapped modes to generate ‘intermediate’ waves of negative energy that are damped as they approach either their corotation resonance or the inner edge of the disc, resulting in amplification of the trapped waves. We determine the growth rates of the inertial modes, as well as their dependence on the spin of the black hole and the properties of the disc. Our results indicate that this coupling mechanism can provide an efficient excitation of trapped inertial waves, provided the global deformations reach the inner part of the disc with non‐negligible amplitude.

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Section: Variation Of Disc Tilt With Radiussupporting

confidence: 81%

Section: Warped Discsmentioning

confidence: 92%

On an excitation mechanism for trapped inertial waves in discs around black holes

Ferreira

Ogilvie

2008

Monthly Notices RAS

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“…The derivation of these equations lies beyond the scope of our paper, but can be found in papers by Papaloizou & Pringle (1983), PL, Demianski & Ivanov (1997) and Ivanov & Illarionov (1997) (hereafter II). Note that equations (28) and (29) are applicable not only to the case of a binary system, but also for general perturbing forces which can cause apsidal and nodal precession of the disc gas trajectories in the linear approximation over the angle b (Demianski & Ivanov 1997; II).…”

Section: T H E T W I S T E D Ac C R E T I O N D I S C a R O U N D T Hmentioning

confidence: 99%

The evolution of a supermassive binary caused by an accretion disc

Ivanov¹,

Papaloizou²,

Polnarev³

1999

Monthly Notices of the Royal Astronomical Society

249

380

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The interaction between a massive binary and a non-self-gravitating circumbinary accretion disc is considered. The shape of the stationary twisted disc produced by the binary is calculated. It is shown that the inner part of the disc must lie in the binary orbital plane for any value of the ivi@tfa.fy.chalmers.se viscosity.When the inner disc midplane is aligned with the binary orbital plane on the scales of interest and it rotates in the same sense as the binary, the modification to the disc structure and the rate of decay of the binary orbit, assumed circular, due to tidal exchange of angular momentum with the disc, are calculated. It is shown that the modified disc structure is well described by a self-similar solution of the non-linear diffusion equation governing the evolution of the disc surface density. The calculated time scale for decay of the binary orbit is always smaller than "accretion" time scale t acc = m/Ṁ (m is the mass of secondary component, andṀ is the disc accretion rate), and is determined by ratio of secondary mass m, assumed to be much smaller than the primary mass, the disc mass inside the initial binary orbit, and the form of viscosity in the disc.

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“…In the framework of the hydrodynamical theory of perturbations, Papaloizou & Pringle (1983) pointed out that the simple model developed in the previous works is, in fact, inconsistent since it does not conserve all components of the angular momentum content of an accretion disc. They showed that a self-consistent model must necessarily contain perturbations of the disc density and velocity fields induced by the disc twist, which determine deviations of the gas particle motion in the disc from the circular one (see Ivanov & Illarionov 1997 for a qualitative explanation of this effect). In particular, the velocity perturbations should be odd with respect to the disc vertical coordinate thus having the structure of a shear flow.…”

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confidence: 99%

A fully relativistic twisted disc around a slowly rotating Kerr black hole: derivation of dynamical equations and the shape of stationary configurations

Zhuravlev

Ivanov

2011

Monthly Notices of the Royal Astronomical Society

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In this paper we derive equations describing the dynamics and stationary configurations of a twisted fully relativistic thin accretion disc around a slowly rotating black hole. We assume that the inclination angle of the disc is small and that the standard relativistic generalization of the α model of accretion discs is valid when the disc is flat. We find that similar to the case of non‐relativistic twisted discs the disc dynamics and stationary shapes can be determined by a pair of equations formulated for two complex variables describing the orientation of the disc rings and velocity perturbations induced by the twist. We analyse analytically and numerically the shapes of stationary twisted configurations of accretion discs having non‐zero inclinations with respect to the black hole equatorial plane at large distances r from the black hole. It is shown that the stationary configurations depend on two parameters – the viscosity parameter α and the parameter , where δ* is the opening angle (δ*∼h/r, where h is the disc half‐thickness and r is large) of a flat disc and a is the black hole rotational parameter. When a > 0 and the shapes depend drastically on the value of α. When α is small the disc inclination angle oscillates with radius with amplitude and radial frequency of the oscillations dramatically increasing towards the last stable orbit, Rms. When α has a moderately small value the oscillations do not take place but the disc does not align with the equatorial plane at small radii. The disc inclination angle either is increasing towards Rms or exhibits a non‐monotonic dependence on the radial coordinate. Finally, when α is sufficiently large the disc aligns with the equatorial plane at small radii. When a < 0 the disc aligns with the equatorial plane for all values of α. The results reported here may have implications for determining the structure and variability of accretion discs close to Rms as well as for modelling of emission spectra coming from different sources, which are supposed to contain black holes.

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corrections to form factors of D-meson semileptonic decays

Cited by 33 publications

References 24 publications

On an excitation mechanism for trapped inertial waves in discs around black holes

On an excitation mechanism for trapped inertial waves in discs around black holes

The evolution of a supermassive binary caused by an accretion disc

A fully relativistic twisted disc around a slowly rotating Kerr black hole: derivation of dynamical equations and the shape of stationary configurations

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