I´ve just started to study superstrings and I´m working on Polchinski´s book problems. I come from other area and so I´m not used to work with group theory what makes a little difficult to me to understand the solution of exercise 1.5. The solution says that the states with [tex]m^2 =1/ \alpha ´[/tex] form complete representations of SO(D-1), D=26. It is because the states are [tex]\alpha^{i}_{-2} \vert 0,k>[/tex], that are vectors of SO(D-2) and [tex]\alpha^{i}_{-1} \alpha^{j}_{-1} \vert 0,k>[/tex], that are tensors of SO(D-2) and they add up to a representation of SO(D-1). I´ve been trying to understand this, but I couldn´t yet. Why [tex]\alpha^{i}_{-2} \vert 0,k>[/tex] are vectors of SO(D-2) and why [tex]\alpha^{i}_{-1} \alpha^{j}_{-1} \vert 0,k>[/tex] are tensors of SO(D-2)? I know just the basics of representation theory for Lie Groups. Can anyone help me and explain it? I´m sorry for such a basic question, but I´m just a begginer in these matters...(adsbygoogle = window.adsbygoogle || []).push({});

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Beginner´s Question on Bosonic Open Strings

Can you offer guidance or do you also need help?

Draft saved
Draft deleted

**Physics Forums | Science Articles, Homework Help, Discussion**