Lattice study of the scalar and baryon spectra in many-flavor QCD

In the search for a composite Higgs boson in walking technicolor models, many flavor QCD, in particular with [Formula: see text], is an attractive candidate, and has been found to have a composite flavor-singlet scalar as light as the pion. Based on lattice simulations of this theory with the HISQ action, we will present our preliminary results on the scalar decay constant using the fermionic bilinear operator, and on the mass of the lightest baryon state which could be a dark matter candidate. Combining these two results, implications for dark matter direct detection are also discussed.

Present status on experimental search for pentaquarks

It has been ten years since the first report for a positive strangeness pentaquark-like baryon state. However, the existence of the pentaquark state is still controversial. Some contradictions between the experiments are unsolved. In this paper, we review the experimental search for the pentaquark candidates Θ+, Θ++, Ξ- -, [Formula: see text] and N* in detail. We review the experiments with positive results and compare the experiments with similar conditions but opposite results.

CHIRAL LOGARITHMIC QUARK MODEL OF N AND Δ WITH AN A-TERM IN THE MEAN-FIELD APPROXIMATION

The A-term is included in the logarithmic quark sigma model, which is based on chiral symmetry and its spontaneous breaking. We investigate the consequences of this term and its relevance to baryon properties. The field equations have been solved in the mean-field approximation for the hedgehog baryon state. We found that including the A-term in the logarithmic quark model leads to lower energies of the nucleon and delta masses and reduces the values of the sigma commutator σπN(0), proton μp(N), and neutron μn(N) of the magnetic moments. This indicates that the inclusion of the A-term improves the calculated nucleon properties in comparison with previous work and other models.

Charm Decays at B Factories

Recent results relating to charm baryon and meson decays from the Belle and BABAR experiments are presented. In addition to recent observations for charm hyperons, evidence for a new charm baryon state, the Λc(2940), observed in its decay to D0p is also reported. No evidence for doubly charmed baryons is seen in e+e- interactions. A measurement of the spin of the Ω- hyperon is made using decays of the [Formula: see text] and [Formula: see text] baryons. On the assumption that the spin of the parent baryons are J = 1/2, the assignment J = 3/2 is confirmed and both J = 1/2 and also higher spins are excluded. New results on rare, Cabibbo-suppressed decays of charm mesons are also presented.

SEARCHES FOR CHARMED PENTAQUARKS AT CDF

Recently the H 1 Collaboration observed a narrow peak in D*-p invariant mass spectrum from what is believed to be an anti-charmed pentaquark baryon state with [Formula: see text] quark content, produced in deep inelastic scattering in ep collisions at HERA. This new state was tentatively named [Formula: see text] as being an anti-charmed analog of Θ+ pentaquark discovered in 2003 by LEPS Collaboration. The upgraded CDF detector is sensitive to production of charmed pentaquark states in central rapidity region due to ability to trigger on displaced tracks from weakly decaying daughter hadrons. At this conference we report results of searches for anti-charmed pentaquark [Formula: see text] and its charged isospin partner [Formula: see text] in [Formula: see text] collisions at [Formula: see text] at Tevatron.

EVIDENCE FOR A NARROW BARYON STATE WITH |S|=1 AT THE HERMES EXPERIMENT

A narrow baryon state has been found in the channel [Formula: see text] of quasi-real photoproduction on a deuterium target at the HERMES experiment. Its mass is 1528±2.6±2.1 MeV and its width is somewhat larger than the experimental resolution of 4.3-6.2 MeV. This state may be interpreted as the predicted S=+1 exotic Θ+ pentaquark baryon. No signal for a hypothetical Θ++ baryon was observed, indicating that the Θ+ is an isoscalar particle.