The recent confirmation of the charged charmonium like resonance Z(4430) by the LHCb experiment strongly suggests the existence of QCD multi quarks bound states. Some preliminary results about hypothetical flavored tetraquark mesons are reported. Suc
h states are particularly amenable to Lattice QCD studies as their interpolating operators do not overlap with those of ordinary hidden-charm mesons.
The nature of the so-called XYZ states is a long-standing problem. It has been suggested that such particles may be described as compact four-quark states or loosely bound meson molecules. In the present work we analyze the Z_c() -> eta_c rho decay u
sing both approaches. Such channel might provide useful insights on the nature of the Z_c(), helping discriminating between the two different models.
Our recent paper on the Search for Neutron Flux Generation in a Plasma Discharge Electrolytic Cell [1] has as main goal the validation of the experiment in Ref.[2]. As a follow-up, Ref.[3] moves a set of objections on our procedure and presents argum
entations on why the experiments should not yield the same results. We collect here additional material and calculations that contribute to understanding the observed discrepancies. Furthermore we prove that the absence of signals from Indium activation detectors reported also for the experiment of Ref.[2] is a clear indication that neutron production does not occur. [1] R.Faccini et al arXiv:1310.4749 [2] D.Cirillo et al, Key Engineering Materials 495, 104 (2012). [3] A.Widom et al. arXiv:1311.2447
We attempt a description of the recently discovered Z_{c,b} states in terms of Feshbach resonances arising from the interaction between the `closed subspace of hadrocharmonium levels and the `open one of open-charm/beauty thresholds. We show how the
neutrality of the X(3872) might be understood in this scheme and provide a preliminary explanation of the pattern of the measured total widths of X,Z_{c,b}.
Following some recent unexpected hints of neutron production in setups like high-voltage atmospheric discharges and plasma discharges in electrolytic cells, we present a measurement of the neutron flux in a configuration similar to the latter. We use
two different types of neutron detectors, poly-allyl-diglicol-carbonate (PADC, aka CR-39) tracers and Indium disks. At 95% C.L. we provide an upper limit of 1.5 neutrons cm^-2 s^-1 for the thermal neutron flux at ~5 cm from the center of the cell. Allowing for a higher energy neutron component the largest allowed flux is 64 neutrons cm^-2 s^-1. This upper limit is two orders of magnitude smaller than what previously claimed in an electrolytic cell plasma discharge experiment. Furthermore the behavior of the CR-39 is discussed to point our possible sources of spurious signals.
The phenomenology of the so-called X, Y and Z hadronic resonances is hard to reconcile with standard charmonium or bottomonium interpretations. It has been suggested that some of these new hadrons can possibly be described as tightly bound tetraquark
states and/or as loosely bound two-meson molecules. In the present paper we focus on the hypothetical existence of flavored, doubly charmed, tetraquarks. Such states might also carry double electric charge, and in this case, if discovered, they could univocally be interpreted in terms of compact tetraquarks. Flavored tetraquarks are also amenable to lattice studies as their interpolating operators do not overlap with ordinary meson ones. We show that doubly charmed tetraquarks could significantly be produced at LHC from B_c or Xi_bc heavy baryons.
