Microwave-mediated synthesis of N-methyliminodiacetic acid (MIDA) boronates

A library of over 20, mainly aryl or heteroaryl, N-methyliminodiacetic acid (MIDA) boronates have been synthesised. A rapid microwave-mediated (MW) method (5–10 min) has been developed using polyethylene glycol 300 (PEG 300) as solvent. However, acetonitrile (MeCN) and dimethylformamide (DMF) were found to be alternative solvents, the latter especially for 2-substituted aryl boronic acids

Charmonium levels near threshold and the narrow state X(3872) \to \pi^{+}\pi^{-}\jpsi

We explore the influence of open-charm channels on charmonium properties, and profile the 1:3D2, 1:3D3 and 2:1P1 charmonium candidates for X(3872). The favored candidates, the 1:3D2 and 1:3D3 levels, both have prominent radiative decays. The 1:3D2 might be visible in the $D^{0}\bar{D}^{*0}$ channel, while the dominant decay of the 1:3D3 state should be into $D\bar{D}$. We propose that additional discrete charmonium levels can be discovered as narrow resonances of charmed and anticharmed mesons.Comment: 8 pages, 6 figures, uses RevTeX and boxedeps; few transcription errors corrected in Tables IV and VI, three entries added in Table V, updated references. Version to appear in Phys. Rev.

A chromomagnetic mechanism for the X(3872) resonance

The chromomagnetic interaction, with proper account for flavour-symmetry breaking, is shown to explain the mass and coupling properties of the X(3872) resonance as a $J^{PC}$ = 1$^{++}$ state consisting of a heavy quark-antiquark pair and a light one. It is crucial to introduce all the spin-colour configurations compatible with these quantum numbers and diagonalise the chromomagnetic interaction in this basis. This approach thus differs from the molecular picture $D\bar {D}*$ and from the diquark-antidiquark picture.Comment: 4 pages - revtex4 - Typos corrected, refs. added, to be published in Phys. Rev.

Achieving peak brightness in an atom laser

In this paper we present experimental results and theory on the first continuous (long pulse) Raman atom laser. The brightness that can be achieved with this system is three orders of magnitude greater than has been previously demonstrated in any other continuously outcoupled atom laser. In addition, the energy linewidth of a continuous atom laser can be made arbitrarily narrow compared to the mean field energy of a trapped condensate. We analyze the flux and brightness of the atom laser with an analytic model that shows excellent agreement with experiment with no adjustable parameters.Comment: 4 pages, 4 black and white figures, submitted to Physical Revie

Nature of the light scalar mesons

Despite the apparent simplicity of meson spectroscopy, light scalar mesons cannot be accommodated in the usual $q\bar q$ structure. We study the description of the scalar mesons below 2 GeV in terms of the mixing of a chiral nonet of tetraquarks with conventional $q\bar q$ states. A strong diquark-antidiquark component is found for several states. The consideration of a glueball as dictated by quenched lattice QCD drives a coherent picture of the isoscalar mesons.Comment: 14 pages, 1 figure, accepted for publication in Phys. Rev.

Mean field baryon magnetic moments and sumrules

New developments have spurred interest in magnetic moments ($\mu$-s) of baryons. The measurement of some of the decuplet $\mu$-s and the findings of new sumrules from various methods are partly responsible for this renewed interest. Our model, inspired by large colour approximation, is a relativistic self consistent mean field description with a modified Richardson potential and is used to describe the $\mu$-s and masses of all baryons with up (u), down (d) and strange (s) quarks. We have also checked the validity of the Franklin sumrule (referred to as CGSR in the literature) and sumrules of Luty, March-Russell and White. We found that our result for sumrules matches better with experiment than the non-relativistic quark model prediction. We have also seen that quark magnetic moments depend on the baryon in which they belong while the naive quark model expects them to be constant.Comment: 7 pages, no figure, uses epl.cl

Neutrino induced threshold production of two pions and N^*(1440) electroweak form factors

We study the threshold production of two pions induced by neutrinos in nucleon targets. The contribution of nucleon, pion and contact terms are calculated using a chiral Lagrangian. The contribution of the Roper resonance, neglected in earlier studies, has also been taken into account. The numerical results for the cross sections are presented and compared with the available experimental data. It has been found that in the two pion channels with $\pi^+\pi^-$ and $\pi^0\pi^0$ in the final state, the contribution of the $N^*(1440)$ is quite important and could be used to determine the $N^*(1440)$ electroweak transition form factors if experimental data with better statistics become available in the future.Comment: This version corrects a mistake on the helicity amplitudes sign. Additional comments on resonance-background relative sign are added. Other minor corrections. Matches published version. 17 pages, 7 figure