Physics – High Energy Physics – High Energy Physics - Phenomenology
Scientific paper
2002-07-29
Eur.Phys.J.C27:115-134,2003
Physics
High Energy Physics
High Energy Physics - Phenomenology
Published version
Scientific paper
10.1140/epjc/s2002-01098-9
Multi-flavour (N_f>=3) Chiral Perturbation Theory (ChPT) may exhibit instabilities due to vacuum fluctuations of sea q-bar q pairs. Keeping the fluctuations small would require a very precise fine-tuning of the low-energy constants L_4 and L_6 to L_4[crit](M_rho) = - 0.51 * 10^(-3), and L_6[crit](M_rho) = - 0.26 * 10^(-3). A small deviation from these critical values -- like the one suggested by the phenomenology of OZI-rule violation in the scalar channel -- is amplified by huge numerical factors inducing large effects of vacuum fluctuations. This would lead in particular to a strong N_f-dependence of chiral symmetry breaking and a suppression of multi-flavour chiral order parameters. A simple resummation is shown to cure the instability of N_f>=3 ChPT, but it modifies the standard expressions of some O(p^2) and O(p^4) low-energy parameters in terms of observables. On the other hand, for r=m_s/m > 15, the two-flavour condensate is not suppressed, due to the contribution induced by massive vacuum s-bar s pairs. Thanks to the latter, the standard two-flavour ChPT is protected from multi-flavour instabilities and could provide a well-defined expansion scheme in powers of non-strange quark masses.
Descotes-Genon Sebastien
Girlanda Luca
Stern Jan
No associations
LandOfFree
Chiral order and fluctuations in multi-flavour QCD does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Chiral order and fluctuations in multi-flavour QCD, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chiral order and fluctuations in multi-flavour QCD will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-251274