404 research outputs found

    Hadronic B Decays Involving Even Parity Charmed Mesons

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    Hadronic B decays containing an parity-even charmed meson in the final state are studied. Specifically we focus on the Cabibbo-allowed decays Bˉ→D∗∗π(ρ),D∗∗Dˉs(∗),Dˉs∗∗D(∗)\bar B\to D^{**} \pi(\rho), D^{**}\bar D_s^{(*)}, \bar D^{**}_sD^{(*)} and Bˉs→Ds∗∗π(ρ)\bar B_s\to D_s^{**}\pi(\rho), where D∗∗D^{**} denotes generically a p-wave charmed meson. The B→D∗∗B\to D^{**} transition form factors are studied in the improved version of the Isgur-Scora-Grinstein-Wise quark model. We apply heavy quark effective theory and chiral symmetry to study the strong decays of p-wave charmed mesons and determine the magnitude of the D11/2−D13/2D_1^{1/2}-D_1^{3/2} mixing angle. Except the decay to D1(2427)0π−D_1(2427)^0\pi^- the predictions for B−→D∗∗0π−B^-\to D^{**0}\pi^- agree with experiment. The sign of D11/2−D13/2D_1^{1/2}-D_1^{3/2} mixing angle is found to be positive in order to avoid a severe suppression on the production of D1(2427)0π−D_1(2427)^0\pi^-. The interference between color-allowed and color-suppressed tree amplitudes is expected to be destructive in the decay B−→D1(2427)0π−B^-\to D_1(2427)^0\pi^-. Hence, an observation of the ratio D1(2427)0π−/D1(2427)+π−D_1(2427)^0\pi^-/D_1(2427)^+\pi^- can be used to test the relative signs of various form factors as implied by heavy quark symmetry. Although the predicted B−→D1(2420)0ρ−B^-\to D_1(2420)^0\rho^- at the level of 3×10−33\times 10^{-3} exceeds the present upper limit, it leads to the ratio D1(2420)ρ−/D1(2420)π−≈2.6D_1(2420)\rho^-/D_1(2420)\pi^-\approx 2.6 as expected from the factorization approach and from the ratio fρ/fπ≈1.6f_\rho/f_\pi\approx 1.6 . Therefore, it is crucial to have a measurement of this mode to test the factorization hypothesis. For Bˉ→Dˉs∗∗D\bar B\to \bar D_s^{**}D decays, it is expected that \bar D_{s0}^*D\gsim \bar D_{s1}D as the decay constants of the multiplet (Ds0∗,Ds1)(D_{s0}^*,D_{s1}) become the same in the heavy quark limit.Comment: 27 pages, Belle's new data on DD_s^{**} productions in B decays and on the radiative decay D_{s1}-> D_s\gamma are updated and discussed. Add two reference

    Q**2-dependence of deep inelastic lepton scattering off nuclear targets

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    Deep inelastic scattering of leptons off nuclear targets is analized within the convolution model taking into account nucleon-nucleon correlations. We show that in the nuclear medium nucleons are distributed according to a function that exhibits a sizeable Q**2-dependence and reduces to the ordinary light-cone distribution in the Bjorken limit. At Q**2 1 this Q**2-dependence turns out to be stronger than the one associated with the nucleon structure function, predicted by pertubative quantum chromodynamics.Comment: 11 pages including figs. Figs. can be sent by PS-fil

    Pharmacokinetics of midazolam in CYP3A4- and CYP3A5-genotyped subjects

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    OBJECTIVE: We investigated whether differences in pharmacokinetics of midazolam, a CYP3A probe, could be demonstrated between subjects with different CYP3A4 and CYP3A5 genotypes. METHODS: Plasma concentrations of midazolam, and of total (conjugated + unconjugated) 1'OH-midazolam, and 4'OH-midazolam were measured after the oral administration of 7.5 mg or of 75 micro g of midazolam in 21 healthy subjects. RESULTS: CYP3A5*7, CYP3A4*1E, CYP3A4*2, CYP3A4*4, CYP3A4*5, CYP3A4*6, CYP3A4*8, CYP3A4*11, CYP3A4*12, CYP3A4*13, CYP3A4*17 and CYP3A4*18 alleles were not identified in the 21 subjects. CYP3A5*3, CYP3A5*6, CYP3A4*1B and CYP3A4*1F alleles were identified in 20, 1, 4 and 2 subjects, respectively. No statistically significant differences were observed for the AUC(inf) values between the different genotypes after the 75- micro g or the 7.5-mg dose. CONCLUSION: Presently, CYP3A4 and CYP3A5 genotyping methods do not sufficiently reflect the inter-individual variability of CYP3A activity

    Global QCD Analysis and the CTEQ Parton Distributions

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    The CTEQ program for the determination of parton distributions through a global QCD analysis of data for various hard scattering processes is fully described. A new set of distributions, CTEQ3, incorporating several new types of data is reported and compared to the two previous sets of CTEQ distributions. Comparison with current data is discussed in some detail. The remaining uncertainties in the parton distributions and methods to further reduce them are assessed. Comparisons with the results of other global analyses are also presented.Comment: (Change in Latex style only: 2up style removed since many don't have it.) 35 pages, 23 figures separately submitted as uuencoded compressed ps-file; Michigan State Report # MSU-HEP/41024 and CTEQ 40

    Heavy-quark mass dependence in global PDF analyses and 3- and 4-flavour parton distributions

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    We study the sensitivity of our recent MSTW 2008 NLO and NNLO PDF analyses to the values of the charm- and bottom-quark masses, and we provide additional public PDF sets for a wide range of these heavy-quark masses. We quantify the impact of varying m_c and m_b on the cross sections for W, Z and Higgs production at the Tevatron and the LHC. We generate 3- and 4-flavour versions of the (5-flavour) MSTW 2008 PDFs by evolving the input PDFs and alpha_S determined from fits in the 5-flavour scheme, including the eigenvector PDF sets necessary for calculation of PDF uncertainties. As an example of their use, we study the difference in the Z total cross sections at the Tevatron and LHC in the 4- and 5-flavour schemes. Significant differences are found, illustrating the need to resum large logarithms in Q^2/m_b^2 by using the 5-flavour scheme. The 4-flavour scheme is still necessary, however, if cuts are imposed on associated (massive) b-quarks, as is the case for the experimental measurement of Z b bbar production and similar processes.Comment: 40 pages, 11 figures. Grids can be found at http://projects.hepforge.org/mstwpdf/ and in LHAPDF V5.8.4. v2: version published in EPJ

    Oral administration of a low dose of midazolam (75 microg) as an in vivo probe for CYP3A activity.

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    OBJECTIVE: We investigated whether the oral administration of a low dose (75 micro g) of midazolam, a CYP3A probe, can be used to measure the in vivo CYP3A activity. METHODS: Plasma concentrations of midazolam, 1'OH-midazolam and 4'OH-midazolam were measured after the oral administration of 7.5 mg and 75 micro g midazolam in 13 healthy subjects without medication, in four subjects pretreated for 2 days with ketoconazole (200 mg b.i.d.), a CYP3A inhibitor, and in four subjects pretreated for 4 days with rifampicin (450 mg q.d.), a CYP3A inducer. RESULTS: After oral administration of 75 micro g midazolam, the 30-min total (unconjugated + conjugated) 1'OH-midazolam/midazolam ratios measured in the groups without co-medication, with ketoconazole and with rifampicin were (mean+/-SD): 6.23+/-2.61, 0.79+/-0.39 and 56.1+/-12.4, respectively. No side effects were reported by the subjects taking this low dose of midazolam. Good correlations were observed between the 30-min total 1'OH-midazolam/midazolam ratio and midazolam clearance in the group without co-medication (r(2)=0.64, P<0.001) and in the three groups taken together (r(2)=0.91, P<0.0001). Good correlations were also observed between midazolam plasma levels and midazolam clearance, measured between 1.5 h and 4 h. CONCLUSION: A low oral dose of midazolam can be used to phenotype CYP3A, either by the determination of total 1'OH-midazolam/midazolam ratios at 30 min or by the determination of midazolam plasma levels between 1.5 h and 4 h after its administration

    Heavy quarkonium: progress, puzzles, and opportunities

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    A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the BB-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations. The plethora of newly-found quarkonium-like states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b}, and b\bar{c} bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hot- and cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K. Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D. Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A. Petrov, P. Robbe, A. Vair

    Neutron structure function and inclusive DIS from H-3 and He-3 at large Bjorken-x

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    A detailed study of inclusive deep inelastic scattering (DIS) from mirror A = 3 nuclei at large values of the Bjorken variable x is presented. The main purpose is to estimate the theoretical uncertainties on the extraction of the neutron DIS structure function from such nuclear measurements. On one hand, within models in which no modification of the bound nucleon structure functions is taken into account, we have investigated the possible uncertainties arising from: i) charge symmetry breaking terms in the nucleon-nucleon interaction, ii) finite Q**2 effects neglected in the Bjorken limit, iii) the role of different prescriptions for the nucleon Spectral Function normalization providing baryon number conservation, and iv) the differences between the virtual nucleon and light cone formalisms. Although these effects have been not yet considered in existing analyses, our conclusion is that all these effects cancel at the level of ~ 1% for x < 0.75 in overall agreement with previous findings. On the other hand we have considered several models in which the modification of the bound nucleon structure functions is accounted for to describe the EMC effect in DIS scattering from nuclei. It turns out that within these models the cancellation of nuclear effects is expected to occur only at a level of ~ 3%, leading to an accuracy of ~ 12 % in the extraction of the neutron to proton structure function ratio at x ~ 0.7 -0.8$. Another consequence of considering a broad range of models of the EMC effect is that the previously suggested iteration procedure does not improve the accuracy of the extraction of the neutron to proton structure function ratio.Comment: revised version to appear in Phys. Rev. C; main modifications in Section 4; no change in the conclusion

    Charm System Tests of CPT and Lorentz Invariance with FOCUS

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    We have performed a search for CPT violation in neutral charm meson oscillations. While flavor mixing in the charm sector is predicted to be small by the Standard Model, it is still possible to investigate CPT violation through a study of the proper time dependence of a CPT asymmetry in right-sign decay rates for D0→K−π+D^0\to K^-\pi^+ and \d0b\to K^+\pi^-. This asymmetry is related to the CPT violating complex parameter Ο\xi and the mixing parameters xx and yy: ACPT∝ReΟy−ImΟxA_{CPT}\propto{\rm Re} \xi y-{\rm Im} \xi x . Our 95% confidence level limit is −0.0068<ReΟy−ImΟx<0.0234-0.0068<{\rm Re} \xi y-{\rm Im} \xi x<0.0234. Within the framework of the Standard Model Extension incorporating general CPT violation, we also find 95% confidence level limits for the expressions involving coefficients of Lorentz violation of (−2.8<N(x,y,ÎŽ)(Δa0+0.6ΔaZ)<4.8)×10−16(-2.8<N(x,y,\delta)(\Delta a_0 + 0.6 \Delta a_Z)<4.8)\times 10^{-16} GeV, (−7.0<N(x,y,ÎŽ)ΔaX<3.8)×10−16(-7.0<N(x,y,\delta)\Delta a_X<3.8)\times 10^{-16} GeV, and (−7.0<N(x,y,ÎŽ)ΔaY<3.8)×10−16(-7.0<N(x,y,\delta)\Delta a_Y<3.8)\times 10^{-16} GeV, where N(x,y,ÎŽ)N(x,y,\delta) is the factor which incorporates mixing parameters xx, yy and the doubly Cabibbo suppressed to Cabibbo favored relative strong phase ÎŽ\delta.Comment: 12 pages 5 figure

    The K−π+K^-\pi^+ S-wave from the D+→K−π+π+D^+ \to K^-\pi^+\pi^+ decay

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    Using data from FOCUS (E831) experiment at Fermilab, we present a model independent partial-wave analysis of the K−π+K^-\pi^+ S-wave amplitude from the decay D+→K−π+π+D^+ \to K^-\pi^+\pi^+. The S-wave is a generic complex function to be determined directly from the data fit. The P- and D-waves are parameterized by a sum of Breit-Wigner amplitudes. The measurement of the S-wave amplitude covers the whole elastic range of the K−π+K^-\pi^+ system.Comment: 13 pages, 9 figures, submitted to Physics Letters
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