189904940
Multiquark Systems
In this talk we tackle the description of hadron spectroscopy in terms of the constituent quark model. We focus on the mesonic charm sector, where several of the new reported resonances seem to defy their classification as simple quark-antiquark states. We pay special attention to higher order Fock space components in describing excited states of the meson spectra in close connection with the hadron-hadron interaction. The main goal of the present study is a coherent understanding of the low-energy hadron phenomenology without enforcing any particular model, to constrain its characteristics and learn about low-energy realization of the theory.
115324045
The few body problem of the quark-model hadron structure
We discuss recent results of hadron spectroscopy and hadron-hadron interaction within a quark model framework. New experimental data could point to the important role played by higher order Fock space components on low-energy observables. Our aim is to obtain a coherent description of the low-energy hadron phenomenology to constrain QCD phenomenological models and try to learn about low-energy realizations of the theory. This long-range effort is based in adapting few-body techniques to study many-quark systems. PACS numbers:
119867295
The $N\Lambda \Lambda -\Xi NN$ bound state problem
We use a diagrammatic method to derive the Faddeev equations of the coupled NΛΛ–ΞNN system and apply them to the bound-state problem of the channel. We use as input the nucleon–nucleon, nucleon–hyperon and hyperon–hyperon interactions obtained from a chiral constituent quark model. We explore different parametrizations of the quark–quark interacting potential. While the system alone is unbound, the full coupled channel problem NΛΛ–ΞNN may present a three-baryon bound state just below threshold. Different from double- hypernuclei with four nucleons or more, where the Pauli principle acts strongly because there is no room for more that four nucleons in S wave, in H the full interaction can act in S wave.
120223418
Heavy hadron spectroscopy: A quark model perspective
Abstract We present recent results of hadron spectroscopy and hadron–hadron interaction from the perspective of constituent quark models. We pay special attention to the role played by higher order Fock space components in the hadron spectra and the connection of this extension with the hadron–hadron interaction. The main goal of our description is to obtain a coherent understanding of the low-energy hadron phenomenology without enforcing any particular model, to constrain its characteristics and learn about low-energy realization of the theory.
120906120
Double Charmed and Charmless Four-Quark States
We present a systematic and self-consistent analysis of four-quark charmonium states and applied it to study compact four-quark systems and meson-meson molecules. Our results are robust and should serve to clarify the situation of charmonium spectroscopy above the threshold production of charmed mesons.
188638461
Too many $X's$, $Y's$ and $Z's$?
119237428
GRAVITATIONAL FIELD OF A GLOBAL MONOPOLE IN A MODIFIED GRAVITY
In this paper we analyze the gravitational field of a global monopole in the context of f(R) gravity. More precisely, we show that the field equations obtained are expressed in terms of $F(R) = \frac{df(R)}{dR}$. Since we are dealing with a spherically symmetric system, we assume that F(R) is a function of the radial coordinate only. Moreover, adopting the weak field approximation, we can provide all components of the metric tensor. A comparison with the corresponding results obtained in General Relativity and in the Brans-Dicke theory is also made.
118427849
Structure formation in a $\Lambda$ $viscous$ CDM universe
The possibility of dark matter being a dissipative component represents an option for the standard view where cold dark matter (CDM) particles behave on large scales as an ideal fluid. By including a physical mechanism to the dark matter description like viscosity we construct a more realistic model for the universe. Also, the known small scale pathologies of the standard CDM model either disappear or become less severe. We study clustering properties of a $\Lambda$CDM-like model in which dark matter is described as a bulk viscous fluid. The linear power spectrum, the nonlinear spherical "top hat" collapse and the mass functions are presented. We use the analysis with such structure formation tools in order to place an upper bound on the magnitude of the dark matter's viscosity.
119180568
Effective gravitational equations for $f(R)$ braneworld models
Instituto de Fisica Universidade Federal Fluminense, Avenue Gal. Milton Tavares de Souza, s/n, CEP 24210-346 Niteroi-Rio de Janeiro
8958778
Spherically symmetric vacuum solutions of modified gravity theory in higher dimensions
AbstractIn this paper we investigate spherically symmetric vacuum solutions of f(R) gravity in a higher-dimensional spacetime. With this objective we construct a system of non-linear differential equations whose solutions depend on the explicit form assumed for the function 
$F(R)=\frac{df(R)}{dR}$
. We explicit show that for specific classes of this function exact solutions from the field equations are obtained; also we find approximated results for the metric tensor for more general cases admitting F(R) close to the unity.
118504967
Nonlinear dark matter collapse under diffusion
Diffusion is one of the physical processes allowed for describing the large scale dark matter dynamics. At the same time, it can be seen as a possible mechanism behind the interacting cosmologies. We study the non-linear spherical "top-hat" collapse of dark matter which undergoes velocity diffusion into a solvent dark energy field. We show constraints on the maximum magnitude allowed for the dark matter diffusion. Our results reinforce previous analysis concerning the linear perturbation theory.