First case of Chlamydia trachomatis L2b proctitis in a woman

AbstractSince 2003, outbreaks of lymphogranuloma venereum (LGV) have been reported in European countries, North America, and Australia. Current LGV cases have been caused by Chlamydia trachomatis serovar L2. This sexually transmitted infection is predominantly found among men who have sex with men, specifically men who are seropositive for human immunodeficiency virus and have clinical signs of proctitis. The current outbreak has been almost exclusively attributed to a new variant, designated L2b. Although urogenital cases of LGV have been described in the heterosexual population, we report the first case of C. trachomatis L2b proctitis in a woman

Z-boson as "the standard candle" for high precision W-boson physics at LHC

In this paper we propose a strategy for measuring the inclusive W-boson production processes at LHC. This strategy exploits simultaneously the unique flexibility of the LHC collider in running variable beam particle species at variable beam energies, and the configuration flexibility of the LHC detectors. We propose their concrete settings for a precision measurement of the Standard Model parameters. These dedicated settings optimise the use of the Z boson and Drell-Yan pair production processes as ``the standard reference candles''. The presented strategy allows to factorise and to directly measure those of the QCD effects which affect differently the W and Z production processes. It reduces to a level of 10^{-4} the impact of uncertainties in the partonic distribution functions (PDFs) and in the transverse momentum of the quarks on the measurement precision. Last but not the least, it reduces by a factor of 10 an impact of systematic measurement errors, such as the energy scale and the measurement resolution, on the W-boson production observables.Comment: 20 pages, 4 figure

ANALYSE DES NUCLÉONS ÉJECTÉS DANS UNE RÉACTION QUASI ÉLASTIQUE (p, p?) A 400 MeV

Une expérience de coïncidences (p,pγ) a été réalisée avec des protons incidents de 400 MeV sur différentes cibles 24Mg, 27Al, 28Si, 60Ni auprès de 1'accélérateur Saturne

Principle of Balance and the Sea Content of the Proton

In this study, the proton is taken as an ensemble of quark-gluon Fock states. Using the principle of balance that every Fock state should be balanced with all of the nearby Fock states (denoted as the balance model), instead of the principle of detailed balance that any two nearby Fock states should be balanced with each other (denoted as the detailed balance model), the probabilities of finding every Fock state of the proton are obtained. The balance model can be taken as a revised version of the detailed balance model, which can give an excellent description of the light flavor sea asymmetry (i.e., $\bar{u}\not= \bar{d}$) without any parameter. In case of $g\Leftrightarrow gg$ sub-processes not considered, the balance model and the detailed balance model give the same results. In case of $g\Leftrightarrow gg$ sub-processes considered, there is about 10 percent difference between the results of these models. We also calculate the strange content of the proton using the balance model under the equal probability assumption.Comment: 32 latex pages, 4 ps figures, to appear in PR

Flavor and Charge Symmetry in the Parton Distributions of the Nucleon

Recent calculations of charge symmetry violation(CSV) in the valence quark distributions of the nucleon have revealed that the dominant symmetry breaking contribution comes from the mass associated with the spectator quark system.Assuming that the change in the spectator mass can be treated perturbatively, we derive a model independent expression for the shift in the parton distributions of the nucleon. This result is used to derive a relation between the charge and flavor asymmetric contributions to the valence quark distributions in the proton, and to calculate CSV contributions to the nucleon sea. The CSV contribution to the Gottfried sum rule is also estimated, and found to be small

Étude expérimentale et théorique de la production de nuclides légers rapides dans les interactions proton-noyau à haute énergie

Nous donnons la description d'une expérience réalisée au CERN et concernant la production de 1H, 2H, 3H, 3He, 4He lors des interactions proton-noyau (12C, 27Al, 197Au) à des angles variés (30°, 45°, 75°, 105°). Nous présentons également une théorie thermodynamique permettant d'interpréter les résultats expérimentaux obtenus

Flavor Structure of the Nucleon Sea

The recent progress on our understanding of the flavor structure of unpolarized and polarized nucleon sea is reviewed. The large flavor asymmetry between the up and down sea quark distributions is now well established. This asymmetry strongly suggests the importance of the mesonic degrees of freedom in the description of the nucleon sea. The strong connection between the flavor structure and the spin structure of the nucleon sea is emphasized. Possible future measurements for testing various theoretical models are also discussed.Comment: 5pages, 4 figures, Invited talk presented at the QNP2002 conference, Julich, June 200

The sˉs\bar{s}s content of the D-meson at infinite coupling

We calculate the $\bar{s}s$ condensate in the D - and B - mesons using the unquenched hopping parameter expansion at infinite coupling for the Wilson lattice action. We discuss the phenomenological relevance of our result.Comment: 9 pages Latex file plus 2 uuencoded postscript figure

Polarized light-flavor antiquarks from Drell-Yan processes of h+\vec{N}\to\vec{l^{+-}} + l^{-+} + X

We propose a formula to determine the first moment of difference between the polarized $\bar u$- and $\bar d$-quarks in the nucleon, {\it i.e.} $\Delta\bar u-\Delta \bar d$ from the Drell-Yan processes in collisions of unpolarized hadrons with longitudinally polarized nucleons by measuring outgoing lepton helicities. As coefficients in the differential cross section depend on the $u$- and $d$-quark numbers in the unpolarized hadron beam, the difference $\Delta\bar u-\Delta\bar d$ can be independently tested by changing the hadron beam. Moreover, a formula for estimating the $K$-factor in Drell-Yan processes is also suggested.Comment: 10 pages, 1 figur

Chiral Quark Model with Configuration Mixing

The implications of one gluon exchange generated configuration mixing in the Chiral Quark Model ($\chi$QM$_{gcm}$) with SU(3) and axial U(1) symmetry breakings are discussed in the context of proton flavor and spin structure as well as the hyperon $\beta$-decay parameters. We find that $\chi$QM$_{gcm}$ with SU(3) symmetry breaking is able to give a satisfactory unified fit for spin and quark distribution functions, with the symmetry breaking parameters $\alpha=.4$, $\beta=.7$ and the mixing angle $\phi=20^o$, both for NMC and the most recent E866 data. In particular, the agreement with data, in the case of $G_A/G_V, \Delta_8$, F, D, $f_s$ and $f_3/f_8$, is quite striking.Comment: 16 pages, LaTex, Table and Appendix adde