121581020
The renewed challenge of the H dibaryon
We review the theoretical and experimental current status of the H dibaryon. We revise the recent experimental results obtained from double-Λ hypernuclei produced by means of Ξ-capture reactions using different target nuclei. Forthcoming experimental projects are briefly summarized. We also review the recent theoretical quark-model studies, some of them constrained by observables of the strangeness -2 two-baryon sector. Ongoing theoretical efforts by means of lattice QCD are also discussed.
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.
122074768
Doubly charmed exotic mesons: A gift of nature?
Article history: We study doubly charmed exotic states by solving the scattering problem of two D mesons. Our results point to the existence of a stable isoscalar doubly charmed meson with quantum numbers (I) J P = (0)1 + . We perform a thorough comparison to the results obtained within the hyperspherical harmonic formalism. Such exotic states could be measured at LHC and RHIC. Their experimental observation would,
188638461
Too many $X's$, $Y's$ and $Z's$?
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.
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.
118412284
Spherical collapse for unified dark matter models
We study the non-linear spherical "top hat" collapse for Chaplygin and viscous unified cosmologies. The term unified refers to models where dark energy and dark matter are replaced by one single component. For the generalized Chaplygin gas (GCG) we extend previous results of [R. A. A. Fernandes {\it et al}. Physical Review D 85, 083501 (2012)]. We discuss the differences at non-linear level between the GCG with $\alpha=0$ and the $\Lambda$CDM model. We show that both are indeed different. The bulk viscous model which differs from the GCG due to the existence of non-adiabatic perturbations is also studied. In this case, the clustering process is in general suppressed and the viable parameter space of the viscous model that accelerates the background expansion does not lead to collapsed structures. This result challenges the viability of unified viscous models.
118545135
ON THE MOTION OF A TEST PARTICLE AROUND A GLOBAL MONOPOLE IN A MODIFIED GRAVITY
In this paper we suggest an approach to analyze the motion of a test particle in the spacetime of a global monopole within a f(R)-like modified gravity. The field equations are written in a simplified form in terms of . Since we are dealing with a spherically symmetric metric, we express F(R) as a function of the radial coordinate only, e.g., . So, the choice of a specific form for f(R) will be equivalent to adopt an Ansatz for . By choosing an explicit functional form for , we obtain the weak field solutions for the metric tensor also compute the time-like geodesics and analyze the motion of a massive test particle. An interesting feature is an emerging attractive force exerted by the monopole on the particle.
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.
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.
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.