84 research outputs found
Meson-induced pentaquark productions
Production cross sections of the pentaquark Theta+ baryon in the
meson-induced reactions are calculated for JP=1/2+- and 3/2+- cases. Through
the comparison with the previous measurements at KEK, several quantum numbers
are excluded. The remaining possibilities can be used to cast the upper limit
on the Theta+ width, combining with the result from the J-PARC E19 experiment.Comment: 9 pages, 3 figures, 1 table, version to appear in Prog. Theor. Phy
Chiral Symmetry of Baryons
We study chiral symmetry aspects of the positive and negative parity baryons
by identifying them with linear representations of the chiral group . It is shown that there are two distinctive schemes: naive
and mirror assignments. We construct linear sigma models for baryons in the two
assignments and examine their physical implications. Then we investigate
properties of the naive and mirror nucleons microscopically by using QCD
interpolating fields. Finally, we propose experiments to distinguish the two
chiral assignments for the nucleon.Comment: 36 pages, To appear in Prog. Theor. Phy
Axial anomaly effect on three-quark and five-quark singly heavy baryons
Effects of the axial anomaly on the mass spectrum of singly heavy
baryons (SHBs) is studied in terms of the chiral effective theory based on the
chiral linear representation for light flavors. We consider SHBs made of both
three quarks () and five quarks (). For the three-quark SHBs
we prove that the inverse mass hierarchy for the negative-parity
and is realized only when the anomaly is present. For the
five-quark SHBs, in contrast, it is found that the anomaly does not
change the mass spectrum at the leading order, and accordingly their decay
properties induced by emitting a pseudoscalar meson are not affected by the
anomaly. Moreover, taking into account small mixings between the three-quark
and five-quark SHBs, we find that the observed excited state, either
or , can be consistently regarded as a
negative-parity SHB that is dominated by the five-quark component. We also
predict a new negative-parity five-quark dominant , whose mass is
around MeV and the decay width is of order a few MeV, which provides
useful information for future experiments to check our description.Comment: 15 pages, 10 figure
Influence of Finishing/Polishing Procedures on the Surface Texture of Two Resin Composites
This study compared surface roughness and gloss produced by different finishing/polishing procedures for two resin composites, Clearfil AP-X (AP-X) and Estelite Σ (ES). A total of 70 composite discs (n=35 for each resin composite) were prepared and divided at random into seven finishing/polishing groups (n=5): glass-pressed control; using a super-fine-grit diamond bur (SF); using CompoMaster (CM) after SF-finishing (SF+CM); using White Point (WP) after SF-finishing (SF+WP); using CM after SF+WP-finishing (SF+WP+CM); using Stainbuster (SB) after SF-finishing (SF+SB); and using CM after SF+SB-finishing (SF+SB+CM). After the finishing/polishing procedures, average surface roughness (Ra) and surface gloss (Gs(60°)) of all specimens were assessed with a surface profilometer and specimen gloss meter, respectively. Glass-pressed controls for both AP-X and ES composites showed the best surface finish in terms of both Ra and Gs(60°). SF-finishing produced the roughest surface and led to almost complete loss of gloss. While additional polishing with CM reduced Ra and increased Gs(60°), the additional finishing effect of WP or SB between SF-finishing and CM-polishing was not found for either AP-X or ES
Effect of professional dental prophylaxis on the surface gloss and roughness of CAD/CAM restorative materials
This study aimed to evaluate the effect of dental prophylaxis on the surface gloss and roughness of different indirect restorative materials for computer-aided design/computer-aided manufacturing (CAD/CAM): two types of CAD/CAM composite resin blocks (Shofu Block HC and Estelite Block) and two types of CAD/CAM ceramic blocks (IPS Empress CAD and Celtra DUO). After polishing the CAD/CAM blocks and applying prophylaxis pastes, professional dental prophylaxis was performed using four different experimental protocols (n = 5 each): mechanical cleaning with Merssage Regular for 10 s four times (Group 1); four cycles of mechanical cleaning with Merssage Regular for 10 s and Merssage Fine for 10 s (Group 2); four cycles of mechanical cleaning with Merssage Regular for 10 s and Merssage Fine for 30 s (Group 3); and mechanical cleaning with Merssage Fine for 10 s four times (Group 4). A glossmeter was used to measure surface gloss before and after mechanical cleaning, and a contact stylus profilometer was used to measure surface roughness (Ra). Polishing with prophylactic paste led to a significant reduction in surface gloss and increase in surface roughness among resin composite blocks, whereas the polishing-related change in surface gloss or roughness was smaller in Celtra DUO, a zirconia-reinforced lithium silicate block. Changes in surface gloss and roughness due to polishing with a prophylactic paste containing large particles were not improved by subsequent polishing with a prophylactic paste containing fine particles
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