Parton Sum Rules and Improved Scaling Variable

The effect from quark masses and transversal motion on the Gottfried, Bjorken, and Ellis-Jaffe sum rules is examined by using a quark-parton model of nucleon structure functions based on an improved scaling variable. Its use results in corrections to the Gottfried, Bjorken, and Ellis-Jaffe sum rules. We use the Brodsky-Huang-Lepage prescription of light-cone wavefunctions to estimate the size of the corrections. We constrain our choice of parameters by the roughly known higher twist corrections to the Bjorken sum rule and find that the resulting corrections to the Gottfried and Ellis-Jaffe sum rules are relevant, though not large enough to explain the observed sum rule violations.Comment: latex, with 1 postscript figure, to be published in Phys.Lett.

Gluon Fusion: A Probe of Higgs Sector CP Violation

We demonstrate that CP violation in the Higgs sector, \eg\ of a multi-doublet model, can be directly probed using gluon-gluon collisions at the SSC. % requires phyzzx.tex macro packageComment: UCD-93-

The Two-Loop Scale Dependence of the Static QCD Potential including Quark Masses

The interaction potential V(Q^2) between static test charges can be used to define an effective charge $\alpha_V(Q^2)$ and a physically-based renormalization scheme for quantum chromodynamics and other gauge theories. In this paper we use recent results for the finite-mass fermionic corrections to the heavy-quark potential at two-loops to derive the next-to-leading order term for the Gell Mann-Low function of the V-scheme. The resulting effective number of flavors $N_F(Q^2/m^2)$ in the $\alpha_V$ scheme is determined as a gauge-independent and analytic function of the ratio of the momentum transfer to the quark pole mass. The results give automatic decoupling of heavy quarks and are independent of the renormalization procedure. Commensurate scale relations then provide the next-to-leading order connection between all perturbatively calculable observables to the analytic and gauge-invariant $\alpha_V$ scheme without any scale ambiguity and a well defined number of active flavors. The inclusion of the finite quark mass effects in the running of the coupling is compared with the standard treatment of finite quark mass effects in the $\bar{MS}$ scheme.Comment: 27 pages, 13 figure

Jet Production in Polarized Lepton-Hadron Scattering

We calculate exact analytical expressions for \oas 3-jet and \oasz \\ 4-jet cross sections in polarized deep inelastic lepton nucleon scattering. Introducing an invariant jet definition scheme, we present differential distributions of 3- and 4-jet cross sections in the basic kinematical variables $x$ and $W^2$ as well as total jet cross sections and show their dependence on the chosen spin-dependent (polarized) parton distributions. Noticebly differences in the predictions are found for the two extreme choices, i.e. a large negative sea-quark density or a large positive gluon density. Therefore, it may be possible to discriminate between different parametrizations of polarized parton densities, and hence between the different physical pictures of the proton spin underlying these parametrizations.Comment: 35 pages, LaTeX, 9 ps figures available upon request, MAD/PH/827, KA TTP94-

Polarized parton distributions from charged-current deep-inelastic scattering and future neutrino factories

We discuss the determination of polarized parton distributions from charged-current deep-inelastic scattering experiments. We summarize the next-to-leading order treatment of charged-current polarized structure functions, their relation to polarized parton distributions and scale dependence, and discuss their description by means of a next-to-leading order evolution code. We discuss current theoretical expectations and positivity constraints on the unmeasured C-odd combinations Delta q-Delta qbar of polarized quark distributions, and their determination in charged-current deep-inelastic scattering experiments. We give estimates of the expected errors on charged-current structure functions at a future neutrino factory, and perform a study of the accuracy in the determination of polarized parton distributions that would be possible at such a facility. We show that these measurements have the potential to distinguish between different theoretical scenarios for the proton spin structure.Comment: 35 pages, 13 figures, plain TeX with harvmac; Final version, to be published in Nucl. Phys. B. Typo in eq 2.13 corrected and two references adde

T-odd Gluon-Top-Quark Effective Couplings at the CERN Large Hadron Collider

The T-odd top-quark chromoelectric dipole moment (tCEDM) is probed through top-quark-pair production via gluon fusion at the CERN Large Hadron Collider (LHC) by considering the possibility of having polarized protons. The complete analytic expressions for the tree-level helicity amplitudes of gg-> ttbar is also presented. For the derived analytic results we determine the 1-sigma statistical sensitivities to the tCEDM form factor for (i) typical CP-odd observables composed of lepton and anti-lepton momenta from t and tbar semileptonic decays for unpolarized protons, and (ii) a CP-odd event asymmetry for polarized protons by using the so-called Berger-Qiu (BQ) parametrization of polarized gluon distribution functions. We find that at the CERN LHC, the CP-odd energy and angular correlations can put a limit of 10^{-18} to 10^{-17} g_scm on the real and imaginary parts of the tCEDM, while the simple CP-odd event asymmetry with polarized protons could put a very strong limit of 10^{-20} g_scm on the imaginary part of the tCEDM.Comment: 14 pages(LaTeX), 1 Postscript figure(use epsfig.sty

Histological spectrum of pulmonary manifestations in kidney transplant recipients on sirolimus inclusive immunosuppressive regimens

<p>Abstract</p> <p>Background</p> <p>After the introduction of novel effective immunosuppressive therapies, kidney transplantation became the treatment of choice for end stage renal disease. While these new therapies lead to better graft survival, they can also cause a variety of complications. Only small series or case reports describe pulmonary pathology in renal allograft recipients on mTOR inhibitor inclusive therapies. The goal of this study was to provide a systematic review of thoracic biopsies in kidney transplant recipients for possible association between a type of immunosuppressive regimen and pulmonary complications.</p> <p>Methods</p> <p>A laboratory database search revealed 28 of 2140 renal allograft recipients (18 males and 10 females, 25 to 77 years old, mean age 53 years) who required a biopsy for respiratory symptoms. The histological features were correlated with clinical findings including immunosuppressive medications.</p> <p>Results</p> <p>The incidence of neoplasia on lung biopsy was 0.4% (9 cases), which included 3 squamous cell carcinomas, 2 adenocarcinomas, 1 diffuse large B-cell lymphoma, 1 lymphomatoid granulomatosis, and 2 post transplant B-cell lymphoproliferative disorders. Diffuse parenchymal lung disease was identified in 0.4% (9 cases), and included 5 cases of pulmonary hemorrhage, 3 cases of organizing pneumonia and 1 case of pulmonary alveolar proteinosis. Five (0.2%) cases showed histological features indicative of a localized infectious process. Patients on sirolimus had neoplasia less frequently than patients on other immunosuppressive combinations (12.5% vs. 58.3%, <it>p </it>= 0.03). Lung biopsies in 4 of 5 patients with clinically suspected sirolimus toxicity revealed pulmonary hemorrhage as the sole histological finding or in combination with other patterns.</p> <p>Conclusions</p> <p>Our study documents a spectrum of neoplastic and non-neoplastic lesions in renal allograft recipients on current immunosuppressive therapies. Sirolimus inclusive regimens are associated with increased risk of pulmonary toxicity but may be beneficial in cases of posttransplant neoplasia.</p> <p>Virtual Slides</p> <p>The virtual slide(s) for this article can be found here: <url>http://www.diagnosticpathology.diagnomx.eu/vs/3320012126569395</url>.</p

Gluon Polarization from QCD Sum Rules

The gluon polarization $\Delta G$ in a nucleon can be defined in a gauge invariant way as the integral over the Ioffe-time distribution of polarized gluons. We argue that for sufficiently regular polarized gluon distributions $\Delta G$ is dominated by contributions from small and moderate values of the Ioffe-time z < 10. As a consequence $\Delta G$ can be estimated with 20% accuracy from the first two even moments of the polarized gluon distribution, and its behavior at small values of Bjorken x or, equivalently, at large Ioffe-times z. We employ this idea and compute the first two moments of the polarized gluon distribution within the framework of QCD sum rules. Combined with the color coherence hypothesis we obtain an upper limit for $\Delta G \sim 2 \pm 0.5$ at a typical scale $\mu^2 \sim 1 GeV^2$.Comment: 12 pages, Latex, 2 figures include

High energy amplitude as an admixture of "soft" and "hard" Pomerons

In this paper an attempt is made to find an interface of the perturbative BFKL Pomeron with the non-perturbative Pomeron originating from non-perturbative QCD phenomena such as QCD instantons and/or scale anomaly. The main idea is that the non-perturbative Pomeron involves a large scale ($M_0 \approx 2 GeV$), which is larger than the scale from which perturbative QCD is applicable. One key result is that even for processes involving a large hard scale (such as DIS) the low $x$ behavior is determined by an effective Pomeron with an intercept having an essential non-perturbative QCD contribution.Comment: 29 pages, 13 fugures. Accepted for publication in Nucl. Phys.

Photon Structure Function in Supersymmetric QCD Revisited

We investigate the virtual photon structure function in the supersymmetric QCD (SQCD), where we have squarks and gluinos in addition to the quarks and gluons. Taking into account the heavy particle mass effects to the leading order in QCD and SQCD we evaluate the photon structure function and numerically study its behavior for the QCD and SQCD cases.Comment: 6 pages, LaTeX 3 eps figures, elsarticle.cls, typos corrected, comments adde