571 research outputs found

    Retail Price Dynamics and Retailer Heterogeneity: UK Evidence

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    We examine retailer heterogeneity in price adjustment in UK supermarkets. Considerable variation in the price change frequency of identically bar-coded products among retail chains is found. Decomposition analysis suggests that price adjustment is evenly split between sales and reference prices with substantive variation across retailers

    Precise QCD predictions for the production of a Z boson in association with a hadronic jet

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    We compute the cross section and differential distributions for the production of a Z boson in association with a hadronic jet to next-to-next-to-leading order (NNLO) in perturbative QCD, including the leptonic decay of the Z boson. We present numerical results for the transverse momentum and rapidity distributions of both the Z boson and the associated jet at the LHC. We find that the NNLO corrections increase the NLO predictions by approximately 1% and significantly reduce the scale variation uncertainty

    The NNLO QCD corrections to Z boson production at large transverse momentum

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    The transverse momentum distribution of massive neutral vector bosons can be measured to high accuracy at hadron colliders. The transverse momentum is caused by a partonic recoil, and is determined by QCD dynamics. We compute the single and double-differential transverse momentum distributions for fully inclusive Z/γ∗ production including leptonic decay to next-to-next-to-leading order (NNLO) in perturbative QCD. We also compute the same distributions normalised to the cross sections for inclusive Z/γ∗ production, i.e. integrated over the transverse momentum of the lepton pair. We compare our predictions for the fiducial cross sections to the 8 TeV data set from the ATLAS and CMS collaborations, which both observed a tension between data and NLO theory predictions, using the experimental cuts and binning. We find that the inclusion of the NNLO QCD effects does not fully resolve the tension with the data for the unnormalised pZT distribution. However, we observe that normalising the NNLO Z-boson transverse momentum distribution by the NNLO Drell-Yan cross section substantially improves the agreement between experimental data and theory, and opens the way for precision QCD studies of this observable

    π+\pi^+ and π0\pi^0 Polarizabilities from {ÎłÎłâ†’Ï€Ï€\gamma\gamma\rightarrow\pi\pi} Data on the Base of S-Matrix Approach

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    We suggest the most model-independent and simple description of the ÎłÎłâ†’Ï€Ï€\gamma\gamma\rightarrow\pi\pi process near threshold in framework of S-matrix approach. The amplitudes contain the pion polarizabilities and rather restricted information about ππ\pi \pi interaction. Application of these formulae for description of MARK-II \cite{M2} and Crystal Ball \cite{CB} data gives: (α−ÎČ)C=(6.0±1.2)⋅10−42cm3(\alpha-\beta)^{C}=(6.0\pm 1.2)\cdot 10^{-42} {\rm cm}^{3}, (α−ÎČ)N=(−1.4±2.1)⋅10−42cm3(\alpha-\beta)^{N}=(-1.4\pm 2.1)\cdot 10^{-42} cm^3 (in units system e2=4παe^2 = 4 \pi \alpha) at the experimental values of ππ\pi \pi scattering lengths. Both values are compartible with current algebra predictions.Comment: LaTeX, 14 pages plus 6 figures (not included, available upon request) , ISU-IAP.Th93-03, Irkuts

    3-Fluoro-4-hydroxyprolines:Synthesis, conformational analysis and stereoselective recognition by the VHL E3 ubiquitin ligase for targeted protein degradation

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    Hydroxylation and fluorination of proline alters the pyrrolidine ring pucker and the trans:cis amide bond ratio in a stereochemistry-dependent fashion, affecting molecular recognition of proline-containing molecules by biological systems. While hydroxyprolines and fluoroprolines are common motifs in medicinal and biological chemistry, the synthesis and molecular properties of prolines containing both modifications, i.e., fluoro-hydroxyprolines, have not been described. Here we present a practical and facile synthesis of all four diastereoisomers of 3-fluoro-4-hydroxyprolines (F-Hyps), starting from readily available 4-oxo-l-proline derivatives. Small-molecule X-ray crystallography, NMR spectroscopy, and quantum mechanical calculations are consistent with fluorination at C<sup>3</sup> having negligible effects on the hydrogen bond donor capacity of the C<sup>4</sup> hydroxyl, but inverting the natural preference of Hyp from C<sup>4</sup>-exo to C<sup>4</sup>-endo pucker. In spite of this, F-Hyps still bind to the von Hippel–Lindau (VHL) E3 ligase, which naturally recognizes C<sup>4</sup>-exo Hyp in a stereoselective fashion. Co-crystal structures and electrostatic potential calculations support and rationalize the observed preferential recognition for (3<i>R</i>,4<i>S</i>)-F-Hyp over the corresponding (3<i>S</i>,4<i>S</i>) epimer by VHL. We show that (3<i>R</i>,4<i>S</i>)-F-Hyp provides bioisosteric Hyp substitution in both hypoxia-inducible factor 1 alpha (HIF-1α) substrate peptides and peptidomimetic ligands that form part of PROTAC (proteolysis targeting chimera) conjugates for targeted protein degradation. Despite a weakened affinity, Hyp substitution with (3<i>S</i>,4<i>S</i>)-F-Hyp within the PROTAC MZ1 led to Brd4-selective cellular degradation at concentrations >100-fold lower than the binary <i>K</i><sub>d</sub> for VHL. We anticipate that the disclosed chemistry of 3-fluoro-4-hydroxyprolines and their application as VHL ligands for targeted protein degradation will be of wide interest to medicinal organic chemists, chemical biologists, and drug discoverers alike

    Photon-Photon Scattering, Pion Polarizability and Chiral Symmetry

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    Recent attempts to detect the pion polarizability via analysis of ÎłÎłâ†’Ï€Ï€\gamma\gamma\rightarrow\pi\pi measurements are examined. The connection between calculations based on dispersion relations and on chiral perturbation theory is established by matching the low energy chiral amplitude with that given by a full dispersive treatment. Using the values for the polarizability required by chiral symmetry, predicted and experimental cross sections are shown to be in agreement.Comment: 21 pages(+10 figures available on request), LATEX, UMHEP-38

    High-Speed Cylindrical Collapse of Two Perfect Fluids

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    In this paper, the study of the gravitational collapse of cylindrically distributed two perfect fluid system has been carried out. It is assumed that the collapsing speeds of the two fluids are very large. We explore this condition by using the high-speed approximation scheme. There arise two cases, i.e., bounded and vanishing of the ratios of the pressures with densities of two fluids given by cs,dsc_s, d_s. It is shown that the high-speed approximation scheme breaks down by non-zero pressures p1,p2p_1, p_2 when cs,dsc_s, d_s are bounded below by some positive constants. The failure of the high-speed approximation scheme at some particular time of the gravitational collapse suggests the uncertainity on the evolution at and after this time. In the bounded case, the naked singularity formation seems to be impossible for the cylindrical two perfect fluids. For the vanishing case, if a linear equation of state is used, the high-speed collapse does not break down by the effects of the pressures and consequently a naked singularity forms. This work provides the generalisation of the results already given by Nakao and Morisawa [1] for the perfect fluid.Comment: 11 pages, 1 figure, accepted for publication in Gen. Rel. Gra

    Energetics of the Einstein-Rosen spacetime

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    A study covering some aspects of the Einstein--Rosen metric is presented. The electric and magnetic parts of the Weyl tensor are calculated. It is shown that there are no purely magnetic E--R spacetimes, and also that a purely electric E--R spacetime is necessarily static. The geodesics equations are found and circular ones are analyzed in detail. The super--Poynting and the ``Lagrangian'' Poynting vectors are calculated and their expressions are found for two specific examples. It is shown that for a pulse--type solution, both expressions describe an inward radially directed flow of energy, far behind the wave front. The physical significance of such an effect is discussed.Comment: 19 pages Latex.References added and updated.To appear in Int.J.Theor.Phy

    Characteristic cohomology of pp-form gauge theories

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    The characteristic cohomology Hchark(d)H^k_{char}(d) for an arbitrary set of free pp-form gauge fields is explicitly worked out in all form degrees k<n−1k<n-1, where nn is the spacetime dimension. It is shown that this cohomology is finite-dimensional and completely generated by the forms dual to the field strengths. The gauge invariant characteristic cohomology is also computed. The results are extended to interacting pp-form gauge theories with gauge invariant interactions. Implications for the BRST cohomology are mentioned.Comment: Latex file, no figures, 44 page
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