Volume 78, Number 6, June 2007
Article Number 68003
Number of page(s) 6
Section Interdisciplinary Physics and Related Areas of Science and Technology
Published online 29 May 2007
EPL, 78 (2007) 68003
DOI: 10.1209/0295-5075/78/68003

Random RNA under tension

F. David1, C. Hagendorf1, 2 and K.-J. Wiese2

1  Service de Physique Théorique, CEA Saclay - 91191 Gif-sur-Yvette, France
2  CNRS-Laboratoire de Physique Théorique de l'Ecole Normale Supérieure - 24, rue Lhomond, 75231 Paris cedex 05, France

received 13 February 2007; accepted in final form 7 May 2007; published June 2007
published online 29 May 2007

The Lässig-Wiese (LW) field theory for the freezing transition of random RNA secondary structures is generalized to the situation of an external force. We find a second-order phase transition at a critical applied force f=fc. For f < fc forces are irrelevant. For f > fc, the extension $\cal L $ as a function of pulling force f scales as ${\cal L}(f) \sim (f-f_{c})^{1/\gamma-1} $. The exponent $\gamma $ is calculated in an $\epsilon$-expansion: At 1-loop order $\gamma =\epsilon/2=1/2$, equivalent to the disorder-free case. 2-loop results yielding $\gamma =0.6$ are briefly mentioned. Using a locking argument, we speculate that this result extends to the strong-disorder phase.

87.15.Cc - Folding and sequence analysis.
05.70.Jk - Critical point phenomena.
64.70.Pf - Glass transitions.

© Europhysics Letters Association 2007