The Color-Octet Contributions to PP-wave BcB_c Meson Hadroproduction

The contributions from the color-octet components $|(c\bar b)_{\bf 8}(^{1}S_{0}) g>$ and $|(c\bar b)_{\bf 8}(^{3}S_{1}) g>$ to the $h_{B_c}$ or $\chi_{B_c}^J$ (the $P$-wave $B_c$ meson) hadroproduction are estimated in terms of the complete ${\cal O}(\alpha_s^4)$ calculation. As necessary inputs in the estimate, we take the values of the octet matrix elements according to the NRQCD scaling rules, and as a result, we have found that the contributions to the $P$-wave production may be the same in order of magnitude as those from the color-singlet ones, $|(c\bar b)_{\bf 1}(^{1}P_{1})>$ and $|(c\bar b)_{\bf 1}(^{3}P_{J})>$ ($J=1,2,3$). Especially, our result indicates that the observation of the color-octet contributions to the $P$-wave production in the low transverse momentum region is not very far from the present experimental capability at Tevatron and LHC.Comment: 14 pages, 4 figures (8 eps-files for figures), add references and correct typo

Successful Resection of a Mycotic Aneurysm of the Superior Mesenteric Artery

AbstractAneurysm of the superior mesenteric artery is rare. More than 50% are mycotic. An aneurysm at this site ruptures easily and is difficult to manage. Here, we report a 49-year-old man with a mycotic aneurysm of the superior mesenteric artery, which was successfully resected, with revascularization from the infrarenal aorta using a retrograde vein graft

Estimate of the Hadronic Production of the Doubly Charmed Baryon Ξcc\Xi_{cc} under GM-VFN Scheme

Hadronic production of the doubly charmed baryon $\Xi_{cc}$ ($\Xi^{++}_{cc}$ and $\Xi^{+}_{cc}$) is investigated under the general-mass variable-flavor-number (GM-VFN) scheme. The gluon-gluon fusion mechanism and the intrinsic charm mechanisms, i.e. via the sub-processes $g+g\to(cc)[^3S_1]_{\bar 3}+\bar{c}+\bar{c}$, $g+g\to(cc)[^1S_0]_6+\bar{c}+\bar{c}$; $g+c\to (cc)[^3S_1]_{\bar 3}+\bar{c}$, $g+c\to (cc)[^1S_0]_6+\bar{c}$ and $c+c\to (cc)[^3S_1]_{\bar 3}+g$, $c+c\to (cc)[^1S_0]_6+g$, are taken into account in the investigation, where $(cc)[^3S_1]_{\bar 3}$ (in color {\bf $\bar 3$}) and $(cc)[^1S_0]_6$ (in color {\bf 6}) are two possible $S$-wave configurations of the doubly charmed diquark pair $(cc)$ inside the baryon $\Xi_{cc}$. Numerical results for the production at hadornic colliders LHC and TEVATRON show that both the contributions from the doubly charmed diquark pairs $(cc)[^1S_0]_6$ and $(cc)[^3S_1]_{\bar 3}$ are sizable with the assumption that the two NRQCD matrix elements are equal, and the total contributions from the `intrinsic' charm mechanisms are bigger than those of the gluon-gluon fusion mechanism. For the production in the region of small transverse-momentum $p_t$, the intrinsic mechanisms are dominant over the gluon-gluon fusion mechanism and they can raise the theoretical prediction of the $\Xi_{cc}$ by almost one order.Comment: 26 pages, 8 figure

Evaluating Feynman integrals by the hypergeometry

The hypergeometric function method naturally provides the analytic expressions of scalar integrals from concerned Feynman diagrams in some connected regions of independent kinematic variables, also presents the systems of homogeneous linear partial differential equations satisfied by the corresponding scalar integrals. Taking examples of the one-loop $B_{_0}$ and massless $C_{_0}$ functions, as well as the scalar integrals of two-loop vacuum and sunset diagrams, we verify our expressions coinciding with the well-known results of literatures. Based on the multiple hypergeometric functions of independent kinematic variables, the systems of homogeneous linear partial differential equations satisfied by the mentioned scalar integrals are established. Using the calculus of variations, one recognizes the system of linear partial differential equations as stationary conditions of a functional under some given restrictions, which is the cornerstone to perform the continuation of the scalar integrals to whole kinematic domains numerically with the finite element methods. In principle this method can be used to evaluate the scalar integrals of any Feynman diagrams.Comment: 39 pages, including 2 ps figure