Nonlocal Dynamics in String Field Theory and cosmological applications Liudmila Joukovskaya, CTC, DAMTP, University of Cambridge 21 January, Imperial College London
Plan of the talk General Motivations Construction of rolling solutions in the truncated SFT a) Truncated SFT (nonlocality) b) Space homogeneous rolling solutions Cosmological motivations for nonlocal theories SFT as a possible framework for cosmology Rolling cosmological solutions
Motivations Cosmological Motivations Theoretical Motivations String Field Theory as a possible framework for Cosmology
Cubic Fermionic String Field Theory Witten’s Cubic Open String Field Theory I.Aref’eva, P.Medvedev, A.Zubarev Phys.Lett. B240 (1990)356 C.Preitschopf, C.Thorn, S.Yost, Nucl. Phys. B337 (1990) 363 I.Arefeva, D.Belov, A.Koshelev, P.Medvedev, Nucl.Phys.B638 (2002)3 E. Witten, Nucl. Phys. B 268 (1986) 253 V.A. Kostelecky, S.Samuel, Phys. Lett. B 207 (1988) 169 V.A. Kostelecky,S.Samuel, Phys. Lett. B 207 (1988) 169, P.West, Phys.Lett.B548:92-96,2002 N. Moeller, A. Sen, B. Zwiebach, JHEP, 08 (2000) 039
In the approximation u=U we have a more simple approximate action
Covariant String Field Theory Level truncation
Spatially-Homogeneous Configurations
Stress Tensor N. Moeller, B. Zwiebach, JHEP, 10 (2002) 034 H. Yang, JHEP 11 (2002) 007 I. Aref’eva, L.J., A. Koshelev, JHEP, 09 (2003) 012
Intuition about possible solutions
Solution construction for Minkowski case Ya. Volovich, JPA, 2003; Ya. Volovich, V.S. Vladimirov, Theor. Math. Phys. 2004; L.J., Theor. Math. Phys or arxiv: [hep-th]; V.S. Vladimirov, arxiv: D. V. Prokhorenko, math-ph/ ; G. Calcagni, G. Nardelli, arxiv:
Solution of Equation of Motion
Standard Cosmological Concordance Model is emerging during the last 10 years …
Big Bang/Inflationary Cosmology Picture taken from: cosmology.berkeley.edu
Cyclic/Ekpyrotic Cosmology N. Turok, P.J. Steinhardt, J. Khoury, B. Ovrut
A great discovery of the last few years is the discovery of the current accelerated expansion of the Universe Observations (1998) of very distant supernovae demonstrated that the Universe is expanding with an acceleration. Ia Supernovae: S.Perlmutter et al., A.Riess et al., 1998; This acceleration seems to be explicable by the presence of a new component of matter called dark energy (DE). DE is a special unknown form of matter with negative pressure and it provides universal repulsive forces (antigravity).
Picture taken from: map.gsfc.nasa.gov
One more reason to work on new inflationary candidates
String Field Theory as a possible cosmological framework Standard Cosmological Concordance Model is emerging during the last 10 years…
Non-locality and Cosmology Non-local gravity ad-hoc: Non-local SFT: Arkani-Hamed at al hep-th/ ; Khoury, hep-th/ ; T.Biswas, A.Mazumdar, W.Siegel, hep-th/ , G.Dvali, S. Hofmann, JKhoury, hep-th/ G.Dvali, S. Hofmann, J Khoury, hep-th/ S.Deser, R.Woodard, arXiv S. S.Deser, R.Woodard, arXiv: S. I.Aref’eva, LJ, A.Koshelev, JHEP, 2003; I.Aref’eva, LJ, JHEP, 2005 G.Calcagni, JHEP, 2005 LJ, PRD 2007 G. Calcagni, M.Montobbio, G.Nardelli; PRD 2007 N. Barnaby, T. Biswas, J.M. Cline, JHEP 2007 J.Lidsey, PRD 2007; D. Mulryne, N. Nunes, PRD 2008
Friedmann Cosmology Einstein equations + Cosmological principle Homogeneous Isotropic K=+1 (3-sphere), k=0 (plane), k=-1 (3-hyperboloid)
Intuition about possible solutions
L.J., PRD 2007
Two fields case
Second possibility
Numerical Scheme for Solution Construction II
Numerical Scheme for Solution Construction II - continuation
Numerical Solution
Does exist the rolling tachyon solution in the case of cubic potential?
Coupling to the gravity / FRW case
Do we have the rolling tachyon solution in this case?
L.J., arxiv:
Numerical solutions a. b.
Energy and pressure for Rolling Tachyon Solutions a. b.
Main results presented in this talk: Construction of rolling cosmological solutions for: Tachyon field describing non-BPS branes in Friedmann-Robertson-Walker background ( Does exist in Minkowski case AJK ) Tachyon field of open bosonic string in Friedmann-Robertson-Walker background ( Does not exist in the Minkowski case (Moeller, Zwiebach) )
Conclusions and further directions
Thank you for the attention!