Skip to the Main Content

Note:These pages make extensive use of the latest XHTML and CSS Standards. They ought to look great in any standards-compliant modern browser. Unfortunately, they will probably look horrible in older browsers, like Netscape 4.x and IE 4.x. Moreover, many posts use MathML, which is, currently only supported in Mozilla. My best suggestion (and you will thank me when surfing an ever-increasing number of sites on the web which have been crafted to use the new standards) is to upgrade to the latest version of your browser. If that's not possible, consider moving to the Standards-compliant and open-source Mozilla browser.

October 8, 2003

Skyrme Fun

A while back, I wrote about the possible discovery of an exotic baryon state, Φ +\Phi^+, with mass m=1540MeVm=1540 \mathrm{MeV}, width Γ<22MeV\Gamma\lt 22 MeV and flavour quantum numbers uudds¯u u d d \overline{s}. Truth be told, this was but one of several observations of the same resonance.

What I didn’t say was that this flurry of experimental work was actually the result of a theoretical prediction of the existence of this state on the basis of Skyrme model calculations by Diakonov, Petrov & Polyakov. They found a set of states in the 10¯\overline{10} of SU(3)SU(3). By fitting the masses of two of these excitations to the observed N(1710) and Σ\Sigma(1880) resonances, they predicted that the lightest member of the 10¯\overline{10} would be the Φ +\Phi^+, with a mass and width (m=1530MeVm=1530 \mathrm{MeV}, Γ<15MeV\Gamma\lt 15 \mathrm{MeV}) extremely close to the (now) experimentally-observed values.

Recently, Itzhaki, Klebanov, Ouyang, and Rastelli have looked a little more closely at the large-N cN_c Skyrme Model. They argue that, in the “bound state” approach of Callan & Klebanov (Nucl. Phys. B262 (1985) 365), this resonance does not appear — unless you do something rather artificial, like crank up the SU(3) symmetry-breaking (m s>1GeVm_s \gt 1\mathrm{GeV}).

I don’t know what to make of this. Diakonov et al’s “rigid rotator” approximation results at N c=3N_c=3 are way too good to be dismissed out-of-hand. It would be sad if there weren’t a clean way to derive them from large-N cN_c.

Posted by distler at October 8, 2003 12:40 AM

TrackBack URL for this Entry:   https://golem.ph.utexas.edu/cgi-bin/MT-3.0/dxy-tb.fcgi/232

0 Comments & 0 Trackbacks

Post a New Comment