arXiv subjects

M. Braun

Publications and source records attributed to M. Braun.

24 records · Page 2Linked to original sources

arXiv1996

Nonradiative proton--deuteron fusion in stellar plasma

The nuclear reaction e+p+d -----> He3 + e is considered at thermonuclear energies. The motion of the electron is treated within the adiabatic approximation and the pd scattering state is constructed in the form of an antisymmetrized product of the bound state wave function of the deuteron and of the wave function of the pd relative motion. The latter is calculated using an effective pd potential constructed via the Marchenko inverse scattering method. The bound state wave function of He3 is obtained using Faddeev--type integrodifferential equations. The reaction rate thus obtained for the solar interior conditions is approximately 10^{-4} of the corresponding rate for the radiative capture pd ----> He3 + gamma .

nucl-th↗

arXiv1996

The eta-meson light nucleus resonances and quasi-bound states

The position and movement of poles of the amplitude for elastic eta-meson scattering off the light nuclei d, t, ^3He, and ^4He are studied. It is found that, within the existing uncertainties for the elementary eta-N interaction, all these nuclei can support a quasi-bound state. The values of the eta-nucleus scattering lengths corresponding to the critical eta-N interaction which produces a quasi--bound state are given.

nucl-th↗

arXiv1996

Structure Functions and Particle Production in the Cumulative Region: two different exponentials

In the framework of the recently proposed QCD based parton model for the cumulative phenomena in the interactions with nuclei two mechanisms for particle production, direct and spectator ones, are analysed. It is shown that due to final state interactions the leading terms of the direct mechanism contribution are cancelled and the spectator mechanism is the dominant one. It leads to a smaller slope of the cumulative particle production rates compared to the slope of the nuclear structure function in the cumulative region $x>1$, in agreement with the recent experimental data.

hep-ph↗

arXiv1995

Interaction of eta-meson with light nuclei

A microscopic treatment of $η$--nucleus scattering is presented. When applying the underlying exact integral equations, the excitation of the target are neglected, and an input $ηN$ amplitude is chosen which reproduces the $S_{11}(1535)$ resonance. It is shown that the $η$--nucleus scattering lengths are quite sensitive to the $ηN$ parameters and the nuclear wave functions. For a special choice of the parameters an $η{^4\!H}e$ quasi--bound state occurs.

nucl-th↗

arXiv1995

The triple pomeron interaction in the perturbative QCD

The triple pomeron interaction is studied in the perturbative approach of BFKL-Bartels. At finite momentum transfers $\sqrt{-t}$ the contribution factorizes in the standard manner with a triple-pomeron vertex proportional to $1/\sqrt{-t}$. At $t=0$ the contribution is finite, although it grows faster with energy than for finite $t$ and does not factorize.

hep-ph↗

arXiv1995

The bootstrap condition for many reggeized gluons and the photon structure function at low x and large number of colours.

The bootstrap condition is generalized to $n$ reggeized gluons. As a result it is demonstrated that the intercept generated by $n$ reggeized gluons cannot be lower than the one for $n=2$. Arguments are presented that in the limit $N_{c}\rightarrow\infty$ the bootstrap condition reduces the $n$ gluon chain with interacting neighbours to a single BFKL pomeron. In this limit the leading contribution from $n$ gluons corresponds to $n/2$ non-interacting BFKL pomerons (the $n/2$ pomeron cut). The sum over $n$ leads to a unitary $γ^{\ast}γ$ amplitude of the eikonal form.

hep-ph↗