# Physics of D-branes

I was following the question What is a D-brane? and I want to ask further: Does each open string have its own D-brane or pair of branes? Do elementary particles arise from oscillation of strings onto their own D-branes? Is there an object in QFT that is equivalent to a D-brane?

Each string has as endpoint a $Dp$-brane. $D$-branes can be coincident, that means one "living" on top of each other. There is no restriction on the number of D-branes a string can have as boundary. If a string is attached to $n$ D-branes on one side and $m$ on the other then we have a $U(n) \times U(m)$ system that can be interpreted as a gage theory with fields living transforming in the bifundamental representation say.
I a do not know exactly how "particles", as viewed by pheno people, originally arise but D-banes by themselves give rise to gauge theories. E.g. $n$ coincident D3 branes give rise to a conformal gauge theory with gauge group $U(n)$. In the context of brane engineering, attaching other types of branes to the system (in specific ways) can give rise to matter representations as well. Brane engineering has its origins in the Hanany-Witten constructions (check their famous paper). Ibanez's and Uranga's book discuss a lot of string phenomenology and how to obtain SM like field theories.