A chromomagnetic mechanism for the X(3872) resonance

The chromomagnetic interaction, with proper account for flavour-symmetry breaking, is shown to explain the mass and coupling properties of the X(3872) resonance as a $J^{PC}$ = 1$^{++}$ state consisting of a heavy quark-antiquark pair and a light one. It is crucial to introduce all the spin-colour configurations compatible with these quantum numbers and diagonalise the chromomagnetic interaction in this basis. This approach thus differs from the molecular picture $D\bar {D}*$ and from the diquark-antidiquark picture.Comment: 4 pages - revtex4 - Typos corrected, refs. added, to be published in Phys. Rev.

Proposal to improve the behaviour of self-energy contributions to the S-matrix

A simple modification of the definition of the S-matrix is proposed. It is expected that the divergences related to nonzero self-energies are considerably milder with the modified definition than with the usual one. This conjecture is verified in a few examples using perturbation theory. The proposed formula is written in terms of the total Hamiltonian operator and a free Hamiltonian operator and is therefore applicable in any case when these Hamiltonian operators are known.Comment: 24 pages, 1 figure; v2: revised version; v3: section 3 improved. Accepted for publication in Central European Journal of Physics; v4: minor text misprints correcte

Production of the Smallest QED Atom: True Muonium (mu^+ mu^-)

The "true muonium" (mu^+ mu-) and "true tauonium" (tau^+ tau^-) bound states are not only the heaviest, but also the most compact pure QED systems. The rapid weak decay of the tau makes the observation of true tauonium difficult. However, as we show, the production and study of true muonium is possible at modern electron-positron colliders.Comment: 4 pages, ReVTeX, 4 eps figures; minor wording changes and reordering of a reference. Version accepted by Phys. Rev. Let

Compared efficacy of preservation solutions in liver transplantation: A long-term graft outcome study from the european liver transplant registry

International audienceBetween 2003 and 2012, 42 869 first liver transplantations performed in Europe with the use of either University of Wisconsin solution (UW; N = 24 562), histidine-tryptophan-ketoglutarate(HTK; N = 8696), Celsior solution (CE; N = 7756) or Institute Georges Lopez preservation solution (IGL-1; N = 1855) preserved grafts. Alternative solutions to the UW were increasingly used during the last decade. Overall, 3-year graft survival was higher with UW, IGL-1 and CE (75%, 75% and 73%, respectively), compared to the HTK (69%) (p 12 h or grafts used for patients with cancer (p < 0.0001). For partial grafts, 3-year graft survival was 89% for IGL-1, 67% for UW, 68% for CE and 64% for HTK (p = 0.009). Multivariate analysis identified HTK as an independent factor of graft loss, with recipient HIV (+), donor age ≥65 years, recipient HCV (+), main disease acute hepatic failure, use of a partial liver graft, recipient age ≥60 years, no identical ABO compatibility, recipient hepatitis B surface antigen (-), TIT ≥ 12 h, male recipient and main disease other than cirrhosis. HTK appears to be an independent risk factor of graft loss. Both UW and IGL-1, and CE to a lesser extent, provides similar results for full size grafts. For partial deceased donor liver grafts, IGL-1 tends to offer the best graft outcome

Liver grafts procured and discarded by all Belgian centers and transplanted within Eurotransplant network: analysis of cause to decline, a Be-LIAC study

The annual balance between imports and exports of grafts is a matter of debate. We examined the Eurotransplant database of all liver grafts procured within Belgium and Luxemburg which were exported and transplanted abroad. The aim of our study was to analyse the reasons for graft refusal by all Belgian transplant centres and early postoperative evolution. Database between 2015 and 2019 included donor characteristics, reason of offer decline, graft and recipient survival. During the 4 year period 329 grafts were procured in Belgium and transplanted abroad. 163 were exported for HU recipients, 17 no national match recipients (8 AB group, 2 pediatric and 7 other reasons), 19 pay back, 15 splits, 11 not mentioned. Hundred and four grafts were declined by all Belgian centres. Forty seven were declined primary offers and fifty seven livers were distributed by extended allocation. Between them we find out four DCD donors, 83 for medical reasons (age, cytolysis, size mismatch and steatosis). Thirteen livers were accepted and declined at arrival for size mismatch (kept as rescue offer in the same centre). One donor was unstable and two were rejected for positive HCV virology. Only one liver who was primary accepted for a split was transplanted as a whole liver. Two patients presented primary graft nonfunction and three primary graft dysfunction. All of them were retransplanted. Thirteen patients died in the early 3 month postoperative period. Even though higher mortality is expected from marginal grafts, better acceptance rate could be achieved at a national level