Asymmetrically twisted strings

In this letter a new class of twisted strings is presented, with an asymmetry between the holomorphic and antiholomorphic sectors parametrized by integer $N$. Their physical content given massless resonances closed string plus mass-level $N$ spectrum open string. The appeal model singling out (higher spin) massive levels theory together their self/gauge/gravity interactions. Motivated original tree level Kawai-Lewellen-Tye relation for strings, its asymmetrically version at four points conjectured shown to naturally interpolate conventional strings. resulting four-point amplitudes have generalized Virasoro-Shapiro dressing factor.