Abstract
We study a, Ramond-Neveu-Schwarz string with one end fixed on a D0-brane and the other end free as a qualitative guide to the spectrum of hadrons containing one very heavy quark. The mixed boundary conditions break half of the worldsheet supersymmetry and allow only odd α and even d modes in the Ramond sector, while the Neveu-Schwarz oscillators b's become odd-integer moded. Boson-fermion masses can still be matched if space-time is nine-dimensional; thus SO(8) triality still plays a role in the spectrum, although full space-time supersymmetry does not survive. We quantize the system in a temporal-like gauge where X0 ∼ τ. Although the gauge choice eliminates negative-norm states at the outset, there are still even-moded Virasoro and even (odd) moded super-Virasoro constraints to be imposed in the NS(R) sectors. The Casimir energy is now positive in both sectors; there are no tachyons. States for α′M2 ≤ 13/4 are explicitly constructed and found to be organized into SO(8) irreps by (super)constraints, which include a novel "√L0" operator in the Neveu-Schwarz and Γ0 ± I in the Ramond sectors. GSO projections are not allowed. The preconstraint states above the ground state have matching multiplicities, indicating space-time supersymmetry is broken by the (super)constraints. A distinctive physical signature of the system is a, slope twice that of the open RNS string. When both ends are fixed, all leading and subleading trajectories are eliminated, resulting in a spectrum qualitatively similar to the J/ψ and γ particles.
Original language | English |
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Pages (from-to) | 185-204 |
Number of pages | 20 |
Journal | International Journal of Modern Physics A |
Volume | 21 |
Issue number | 1 |
DOIs | |
Publication status | Published - 10 Jan 2006 |
Externally published | Yes |
Keywords
- Heavy quark physics
- String and brane theory
- Supersymmetry phenomenology