Antiproton Production in p+d Reaction at Subthreshold Energies

An enhancement of antiprotons produced in p+d reaction in comparison with ones in p+p elementary reaction is investigated. In the neighborhood of subthreshold energy the enhancement is caused by the difference of available energies for antiproton production. The cross section in p+d reaction, on the other hand, becomes just twice of the one in elementary p+p reaction at the incident energy far from the threshold energy when non-nucleonic components in deuteron target are not considered.Comment: LaTeX,7 pages with 5 eps figure

Equation of state in the PNJL model with the entanglement interaction

The equation of state and the phase diagram in two-flavor QCD are investigated by the Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model with an entanglement vertex between the chiral condensate and the Polyakov-loop. The entanglement-PNJL (EPNJL) model reproduces LQCD data at zero and finite chemical potential better than the PNJL model. Hadronic degrees of freedom are taken into account by the free-hadron-gas (FHG) model with the volume-exclusion effect due to the hadron generation. The EPNJL+FHG model improves agreement of the EPNJL model with LQCD data particularly at small temperature. The quarkyonic phase survives, even if the correlation between the chiral condensate and the Polyakov loop is strong and hadron degrees of freedom are taken into account. However, the location of the quarkyonic phase is sensitive to the strength of the volume exclusion.Comment: 9 pages, 7 figure

Alkaloids, Diarylheptanoid and Naphthalene Carboxylic Acid Ester from Rhoiptelea chiliantha

Two pyrrolidine alkaloids (1, 2) were isolated from the fruits of Rhoiptelea chiliantha DIEL et HAND.-MAZZ. (Rhoipteleaceae). A diphenyl ether-type diarylheptanoid (3), and a naphthalene carboxylic acid methyl ester (4) which is biogenetically-related to juglone were isolated from the branches of the same plant. Their chemical structures were elucidated on the basis of spectroscopic analysis and chemical evidence

On Nonperturbative Calculations in Quantum Electrodynamics

A new approach to nonperturbative calculations in quantum electrodynamics is proposed. The approach is based on a regular iteration scheme for solution of Schwinger-Dyson equations for generating functional of Green functions. The approach allows one to take into account the gauge invariance conditions (Ward identities) and to perform the renormalization program. The iteration scheme can be realized in two versions. The first one ("perturbative vacuum") corresponds to chain summation in the diagram language. In this version in four-dimensional theory the non-physical singularity (Landau pole) arises which leads to the triviality of the renormalized theory. The second version ("nonperturbative vacuum") corresponds to ladder summation and permits one to make non-perturbative calculations of physical quantities in spite of the triviality problem. For chiral-symmetrical leading approximation two terms of the expansion of the first-step vertex function over photon momentum are calculated. A formula for anomalous magnetic moment is obtained. A problem of dynamical chiral symmetry breaking (DCSB) is considered, the calculations are performed for renormalized theory in Minkowsky space. In the strong coupling region DCSB-solutions arise. For the renormalized theory a DCSB-solution is also possible in the weak coupling region but with a subsidiary condition on the value of $\alpha$.Comment: 31 pages, Plain LaTex, no figures. Journal version: some discussion and refs. are adde

Holographic Roberge-Weiss Transitions

We investigate N=4 SYM coupled to fundamental flavours at nonzero imaginary quark chemical potential in the strong coupling and large N limit, using gauge/gravity duality applied to the D3-D7 system, treating flavours in the probe approximation. The interplay between Z(N) symmetry and the imaginary chemical potential yields a series of first-order Roberge-Weiss transitions. An additional thermal transition separates phases where quarks are bound/unbound into mesons. This results in a set of Roberge-Weiss endpoints: we establish that these are triple points, determine the Roberge-Weiss temperature, give the curvature of the phase boundaries and confirm that the theory is analytic in mu^2 when mu^2~0.Comment: 37 pages, 13 figures; minor comments added, to appear in JHE

Revised Structure of Cercidinin A, a Novel Ellagitannin Having (R)-Hexahydroxydiphenoyl Esters at the 3, 4-Positions of Glucopyranose

The structue of cercidinin A, an ellagitannin isolated from the bark of Cercidiphyllum japonicum, was revised to 1, 2, 6-tri-O-galloyl-3, 4-(R)-hexahydroxydipenoyl-β-D-glucose by two-dimensional NMR spectral analysis. Cercidinin A represents the first ellagitannin possessing a hexahydroxydiphenoyl group at the 3, 4-positions of a modified 4C1-glucopyranose core