Can Y(4140) be a ccˉssˉc \bar c s \bar s tetraquark ?

In this exploratory study the spectrum of tetraquarks of type $c \bar c s \bar s$ is calculated within a simple quark model with chromomagnetic interaction and effective quark masses extracted from meson and baryon spectra. It is tempting to see if this spectrum can accommodate the resonance Y(4140), observed by the CDF collaboration, but not yet confirmed. The results seem to favour the J$^{PC}$ = 1$^{++}$ sector where the coupling to the VV channel is nearly as small as that of X(3872), when described as a $c \bar c q \bar q$ tetraquark. This suggests that Y(4140) could possibly be the strange partner of X(3872), in a tetraquark interpretation. However the sector J$^{PC}$ = 0$^{++}$ cannot entirely be excluded. This work questions the practice of extracting effective quark masses containing spin independent contributions, from mesons and baryons, to be used in multiquark systems as well.Comment: new additional parts, published versio

Vibrational Satellites of C2_2S, C3_3S, and C4_4S: Microwave Spectral Taxonomy as a Stepping Stone to the Millimeter-Wave Band

We present a microwave spectral taxonomy study of several hydrocarbon/CS$_2$ discharge mixtures in which more than 60 distinct chemical species, their more abundant isotopic species, and/or their vibrationally excited states were detected using chirped-pulse and cavity Fourier-transform microwave spectroscopies. Taken together, in excess of 85 unique variants were detected, including several new isotopic species and more than 25 new vibrationally excited states of C$_2$S, C$_3$S, and C$_4$S, which have been assigned on the basis of published vibration-rotation interaction constants for C$_3$S, or newly calculated ones for C$_2$S and C$_4$S. On the basis of these precise, low-frequency measurements, several vibrationally exited states of C$_2$S and C$_3$S were subsequently identified in archival millimeter-wave data in the 253--280 GHz frequency range, ultimately providing highly accurate catalogs for astronomical searches. As part of this work, formation pathways of the two smaller carbon-sulfur chains were investigated using $^{13}$C isotopic spectroscopy, as was their vibrational excitation. The present study illustrates the utility of microwave spectral taxonomy as a tool for complex mixture analysis, and as a powerful and convenient `stepping stone' to higher frequency measurements in the millimeter and submillimeter bands.Comment: Accepted in PCC

Is S=1 for c=1?

The $c=1$ string in the Liouville field theory approach is shown to possess a nontrivial tree-level $S$-matrix which satisfies factorization property implied by unitary, if all the extra massive physical states are included.Comment: 11 page

H^s versus C^0-weighted minimizers

We study a class of semi-linear problems involving the fractional Laplacian under subcritical or critical growth assumptions. We prove that, for the corresponding functional, local minimizers with respect to a C^0-topology weighted with a suitable power of the distance from the boundary are actually local minimizers in the natural H^s-topology.Comment: 15 page

Spectroscopy of the hidden-charm [qc][qˉcˉ][qc][\bar q \bar c] and [sc][sˉcˉ][sc][\bar s \bar c] tetraquarks

We calculate the spectrum of $q\bar q c \bar c$ and $s\bar s c \bar c$ tetraquarks, where $q$, $s$ and $c$ stand for light ($u,d$), strange and charm quarks, respectively, in a relativized diquark model, characterized by one-gluon-exchange (OGE) plus confining potential. In the diquark model, a $q\bar q c \bar c$ ($s\bar s c \bar c$) tetraquark configuration is made up of a heavy-light diquark, $q c$ ($sc$), and anti-diquark, $\bar q \bar c$ ($\bar s \bar c$). According to our results, 13 charmonium-like observed states can be accommodated in the tetraquark picture, both in the hidden-charm ($q\bar q c \bar c$) and hidden-charm hidden-strange ($s\bar s c \bar c$) sectors.Comment: Discussions extended, references adde