Some aspects of interaction amplitudes of D branes carrying worldvolume fluxes

Abstract

We report a systematic study of the stringy interaction between two sets of Dp branes placed parallel at a separation in the presence of two worldvolume fluxes for each set. We focus in this paper on that the two fluxes on one set have the same structure as those on the other set but they in general differ in values, which can be both electric or both magnetic or one electric and one magnetic. We compute the respective stringy interaction amplitude and find that the presence of electric fluxes gives rise to the open string pair production while that of magnetic ones to the open string tachyon mode. The interplay of these two leads to the open string pair production enhancement in certain cases when one flux is electric and the other is magnetic. In particular, we find that this enhancement occurs even when the electric flux and the magnetic one share one common field strength index which is impossible in the one-flux case studied previously by the present author and his collaborator in [17]. This type of enhancement may have realistic physical applications, say, as a means to explore the existence of extra dimensions.

A note on the open string pair production of the D3/D1 system

“…Our studies indicate that a significantly enhanced open string pair production can be achieved when the applied magnetic field strength does not share any common field strength index with the electric one and as such we need to have p ≥ 3 in general [1,2]. Among these, the p = 3 system actually gives rise to the largest open string pair production rate if the applied electric and magnetic fluxes remain the same for all p ≥ 3.…”

“…In a series of recent publications by the present author and his collaborators [1,2,3,4], we uncover the existence of open string pair production, in the spirit of Schwinger pair production in QED [5], for a system of two Dp branes, placed parallel at a separation, with each carrying electric and magnetic fluxes in Type II superstring theories. The open string pair production for un-oriented bosonic string or un-oriented Type I superstring was discussed a while ago by Bachas and Porrati in [6,7].…”

“…So this can give a small m eff even though either term on the right side of (23) can be on the string scale. In particular, a small tunable magnetic fluxĝ can be useful to tune the parameter ν 1 slightly away from 1/2 from the second equation in (2). This can be used in laboratory to adjust the contribution from the first term on the right side of (23) for a given y π √ α ′ to give a small m eff .…”

On D-brane interaction & its related properties

“…This manifests itself by the appearance of an infinite number of simple poles in the integrand of the integral representation of the open string one-loop annulus amplitude, implying that the interaction amplitude has an imaginary part. Each of these simple poles actually indicates the corresponding open string pair production under the action of the applied electric fluxes [21,25,26]. The imaginary amplitude just reflects the decay of the underlying system via the so-called open string pair production, releasing the excess energy of the system until it reaches the corresponding 1/2 BPS stable one.…”

“…When both electric and magnetic fluxes are present in a certain way, the open string pair production has an enhancement, uncovered recently in [6,18,21,26,30,31].…”