Search results for "Lagrangian"
showing 10 items of 204 documents
Cellular automaton for chimera states
2016
A minimalistic model for chimera states is presented. The model is a cellular automaton (CA) which depends on only one adjustable parameter, the range of the nonlocal coupling, and is built from elementary cellular automata and the majority (voting) rule. This suggests the universality of chimera-like behavior from a new point of view: Already simple CA rules based on the majority rule exhibit this behavior. After a short transient, we find chimera states for arbitrary initial conditions, the system spontaneously splitting into stable domains separated by static boundaries, ones synchronously oscillating and the others incoherent. When the coupling range is local, nontrivial coherent struct…
η–η′ mixing in the flavor basis and large N
2010
Abstract The mass matrix for η – η ′ is derived in the flavor basis at O ( p 4 ) of the chiral Lagrangian using the large N approximation. Under certain assumptions, the mixing angle ϕ = 41.4 ° and the decay constants ratio f K / f π = 1.15 are calculated in agreement with the data. It appears that the FKS scheme arises as a special limit of the chiral Lagrangian. Their mass matrix is obtained without the hypothesis on the mixing pattern of the decay constants.
Dynamical Aspects of Generalized Palatini Theories of Gravity
2009
We study the field equations of modified theories of gravity in which the Lagrangian is a general function of the Ricci scalar and Ricci-squared terms in Palatini formalism. We show that the independent connection can be expressed as the Levi-Civitagrave connection of an auxiliary metric which, in particular cases of interest, is related with the physical metric by means of a disformal transformation. This relation between physical and auxiliary metric boils down to a conformal transformation in the case of f(R) theories. We also show with explicit models that the inclusion of Ricci-squared terms in the action can impose upper bounds on the accessible values of pressure and density, which m…
Correlators of left charges and weak operators in finite volume chiral perturbation theory
2002
We compute the two-point correlator between left-handed flavour charges, and the three-point correlator between two left-handed charges and one strangeness violating \Delta I=3/2 weak operator, at next-to-leading order in finite volume SU(3)_L x SU(3)_R chiral perturbation theory, in the so-called epsilon-regime. Matching these results with the corresponding lattice measurements would in principle allow to extract the pion decay constant F, and the effective chiral theory parameter g_27, which determines the \Delta I = 3/2 amplitude of the weak decays K to \pi\pi as well as the kaon mixing parameter B_K in the chiral limit. We repeat the calculations in the replica formulation of quenched c…
〈VAP〉 Green function in the resonance region
2004
Abstract We analyze the 〈 V A P 〉 three-point function of vector, axial-vector and pseudoscalar currents. In the spirit of large N C , a resonance dominated Green function is confronted with the leading high-energy behaviour from the operator product expansion. The matching is shown to be fully compatible with a chiral resonance Lagrangian and it allows to determine some of the chiral low-energy constants of O ( p 6 ) .
Meson resonances, large N_c and chiral symmetry
2003
14 páginas, 2 tablas.-- arXiv:hep-ph/0305311v1
One-loop Renormalization of Resonance Chiral Theory with Scalar and Pseudoscalar Resonances
2005
The divergent part of the generating functional of the Resonance Chiral Theory is evaluated up to one loop when one multiplet of scalar an pseudoscalar resonances are included and interaction terms which couple up to two resonances are considered. Hence we obtain the renormalization of the couplings of the initial Lagrangian and, moreover, the complete list of operators that make this theory finite, at this order.
Effects of aNcc¯*resonance with hidden charm in theπ−p→D−Σc+reaction near threshold
2015
We study the effect of a hidden charm nuclear excited state ${N}_{c\overline{c}}^{*}$ in the ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{D}^{\ensuremath{-}}{\mathrm{\ensuremath{\Sigma}}}_{c}^{+}$ reaction near threshold using an effective Lagrangian approach. We calculate the background contribution of the $t$ and $u$ channels by the ${D}^{*0}$ vector meson exchange and ${\mathrm{\ensuremath{\Sigma}}}_{c}^{++}$ intermediate state, respectively. We show that the consideration of a ${N}_{c\overline{c}}^{*}$ resonance provides an enhancement of the total cross section close to the reaction threshold. We also evaluate the differential cross section for different energies and w…
Cranked Relativistic Hartree-Bogoliubov Theory: Formalism and Application to the Superdeformed Bands in the $A\sim 190$ region
2000
Cranked Relativistic Hartree-Bogoliubov theory without and with approximate particle number projection by means of the Lipkin-Nogami method is presented in detail as an extension of Relativistic Mean Field theory with pairing correlations to the rotating frame. Pairing correlations are taken into account by a finite range two-body force of Gogny type. The applicability of this theory to the description of rotating nuclei is studied in detail on the example of superdeformed bands in even-even nuclei of the $A\sim 190$ mass region. Different aspects such as the importance of pairing and particle number projection, the dependence of the results on the parametrization of the RMF Lagrangian and …
Moments of inertia of nuclei in the rare earth region: A relativistic versus nonrelativistic investigation
2000
A parameter free investigation of the moments of inertia of ground state rotational bands in well deformed rare-earth nuclei is carried out using Cranked Relativistic Hartree-Bogoliubov (CRHB) and non-relativistic Cranked Hartree-Fock-Bogoliubov (CHFB) theories. In CRHB theory, the relativistic fields are determined by the non-linear Lagrangian with the NL1 force and the pairing interaction by the central part of finite range Gogny D1S force. In CHFB theory, the properties in particle-hole and particle-particle channels are defined solely by Gogny D1S forces. Using an approximate particle number projection before variation by means of the Lipkin Nogami method improves the agreement with the…