Threshold corrections to rapidity distributions of Z and W^\pm bosons beyond N^2 LO at hadron colliders

Threshold enhanced perturbative QCD corrections to rapidity distributions of $Z$ and $W^\pm$ bosons at hadron colliders are presented using the Sudakov resummed cross sections at N${}^3$LO level. We have used renormalisation group invariance and the mass factorisation theorem that these hard scattering cross sections satisfy to construct the QCD amplitudes. We show that these higher order threshold QCD corrections stabilise the theoretical predictions for vector boson production at the LHC under variations of both renormalisation and factorisation scales.Comment: 17 pages, 8 eps figures. This paper is dedicated to the memory of W.L.G.A.M. van Neerve

Soft Resummation of Quark Anomalous Dimensions and Coefficient Functions in MS-bar Factorization

The asymptotic behaviour at large N of the MS-bar quark anomalous dimensions is derived to all orders assuming only MS-bar factorization and standard results for the exponentiation of soft logarithms in the quark initiated bare cross sections for deep inelastic scattering and Drell-Yan. The result is then used to write the MS-bar quark coefficient functions in a form in which all terms of $O(\ln^m N)$ are resummed.Comment: 12 page

Parton distribution functions from the precise NNLO QCD fit

We report the parton distribution functions (PDFs) determined from the NNLO QCD analysis of the world inclusive DIS data with account of the precise NNLO QCD corrections to the evolution equations kernel. The value of strong coupling constant \alpha_s^{NNLO}(M_Z)=0.1141(14), in fair agreement with one obtained using the earlier approximate NNLO kernel by van Neerven-Vogt. The intermediate bosons rates calculated in the NNLO using obtained PDFs are in agreement to the latest Run II results.Comment: 8 pages, LATEX, 2 figures (EPS

Threshold Corrections in Precision LHC Physics: QED otimes QCD

With an eye toward LHC processes in which theoretical precisions of 1 percent are desired, we introduce the theory of the simultaneous YFS resummation of QED and QCD to compute the size of the expected resummed soft radiative threshold effects in precision studies of heavy particle production at the LHC. Our results show that both QED and QCD soft threshold effects must be controlled to be on the conservative side to achieve such precision goals.Comment: 4 pages, no figures; presented by B.F.L. Ward in DPF200

Resummation of Hadroproduction Cross-sections at High Energy

We reconsider the high energy resummation of photoproduction, electroproduction and hadroproduction cross-sections, in the light of recent progress in the resummation of perturbative parton evolution to NLO in logarithms of Q^2 and x. We show in particular that the when the coupling runs the dramatic enhancements seen at fixed coupling, due to infrared singularities in the partonic cross-sections, are substantially reduced, to the extent that they are largely accounted for by the usual NLO and NNLO perturbative corrections. This leads to a novel explanation of the large K-factors commonly found in perturbative calculations of hadroproduction cross-sections. We give numerical estimates of high energy resummation effects for inclusive B-production, inclusive jets, Drell-Yan and vector boson production, along with their rapidity distributions. We find that resummation modifies the B-production cross-section at the LHC by at most 15%, but that the enhancement of gluonic W-production may be as large as 50% at large rapidities.Comment: 49 pages, 25 figures, version to be published in Nucl Phys

Complexity of the Ruminococcus flavefaciens FD-1 cellulosome reflects an expansion of family-related protein-protein interactions

This work was supported in part by the European Union, Area NMP.2013.1.1–2: Self-assembly of naturally occurring nanosystems: CellulosomePlus Project number: 604530, and by the EU Seventh Framework Programme (FP7 2007–2013) under the WallTraC project (Grant Agreement no 263916), and BioStruct-X (grant agreement no 283570). This paper reflects the author’s views only. The European Community is not liable for any use that may be made of the information contained herein. CMGAF is also supported by Fundação para a Ciência e a Tecnologia (Lisbon, Portugal) through grants PTDC/BIA-PRO/103980/2008 and EXPL/BIA-MIC/1176/2012. EAB is also funded by a grant (No. 1349/13) from the Israel Science Foundation (ISF), Jerusalem, Israel and by a grant (No. 2013284) from the U.S.-Israel Binational Science Foundation (BSF). E.A.B. is the incumbent of The Maynard I. and Elaine Wishner Chair of Bio-organic Chemistry.Peer reviewedPublisher PD

h→μτh\to \mu\tau at Hadron Colliders

We study the observability for a lepton flavor-changing decay of a Higgs boson $h\to \mu\tau$ at hadron colliders. Flavor-changing couplings of a Higgs boson exist at tree level in models with multiple Higgs doublets. The $h\mu\tau$ coupling is particularly motivated by the favorable intepretation of $\nu_\mu-\nu_\tau$ oscillation. We find that at the Tevatron Run II the unique $\mu\tau$ signature could serve as the Higgs discovery channel, surpassing expectations for Higgs boson searches in the SM and in a large parameter region of the MSSM. The sensitivity will be greatly improved at the LHC, beyond the coverage at a muon collider Higgs factory.Comment: Version to appear in PR

Observational tests of interstellar methanol formation

Context. It has been established that the classical gas-phase production of interstellar methanol (CH3OH) cannot explain observed abundances. Instead it is now generally thought that the main formation path has to be by successive hydrogenation of solid CO on interstellar grain surfaces. Aims: While theoretical models and laboratory experiments show that methanol is efficiently formed from CO on cold grains, our aim is to test this scenario by astronomical observations of gas associated with young stellar objects (YSOs). Methods: We have observed the rotational transition quartets J = 2K - 1K of 12CH3OH and 13CH3OH at 96.7 and 94.4 GHz, respectively, towards a sample of massive YSOs in different stages of evolution. In addition, the J = 1-0 transitions of 12C18O and 13C18O were observed towards some of these sources. We use the 12C/13C ratio to discriminate between gas-phase and grain surface origin: If methanol is formed from CO on grains, the ratios should be similar in CH3OH and CO. If not, the ratio should be higher in CH3OH due to 13C fractionation in cold CO gas. We also estimate the abundance ratios between the nuclear spin types of methanol (E and A). If methanol is formed on grains, this ratio is likely to have been thermalized at the low physical temperature of the grain, and therefore show a relative over-abundance of A-methanol. Results: We show that the 12C/13C isotopic ratio is very similar in gas-phase CH3OH and C18O, on the spatial scale of about 40", towards four YSOs. For two of our sources we find an overabundance of A-methanol as compared to E-methanol, corresponding to nuclear spin temperatures of 10 and 16 K. For the remaining five sources, the methanol E/A ratio is less than unity. Conclusions: While the 12C/13C ratio test is consistent with methanol formation from hydrogenation of CO on grain surfaces, the result of the E/A ratio test is inconclusive

Oblique Corrections To The W Width

The lowest-order expression for the partial $W$ width to $e \nu ,~\Gamma (W \to e \nu) = G_\mu M_W^3 /(6 \pi \sqrt{2})$, has no oblique radiative corrections from new physics if the measured $W$ mass is used. Here $G_\mu = (1.16639 \pm 0.00002) \times 10^{-5}$ GeV/$c^2$ is the muon decay constant. For the present value of $M_W = (80.14 \pm 0.27)$ GeV/$c^2$, and with $m_t = 140$ GeV$/c^2$, one expects $\Gamma (W \to e \nu) = (224.4 \pm 2.3)$ MeV. The total width $\Gamma_{\rm tot}(W)$ is also expected to lack oblique corrections from new physics, so that $\Gamma_{\rm tot} (W)/ \Gamma (W \to e \nu) = 3 + 6 [1 + \{\alpha_s (M_W)/\pi \}]$. Present data are consistent with this prediction.Comment: 15 pages (LaTeX), one PostScript figure not included (available upon request

Anomalous dimension of the gluon operator in pure Yang-Mills theory

We present new one loop calculations that confirm the theorems of Joglekar and Lee on the renormalization of composite operators. We do this by considering physical matrix elements with the operators inserted at non-zero momentum. The resulting IR singularities are regulated dimensionally. We show that the physical matrix element of the BRST exact gauge variant operator which appears in the energy- momentum tensor is zero. We then show that the physical matrix elements of the classical energy-momentum tensor and the gauge invariant twist two gluon operator are independent of the gauge fixing parameter. A Sudakov factor appears in the latter cases. The universality of this factor and the UV finiteness of the energy-momentum tensor provide another method of finding the anomalous dimension of the gluon operator. We conjecture that this method applies to higher loops and takes full advantage of the triangularity of the mixing matrix.Comment: submitted to Phys. Rev. D, 18 pages LaTEX uses psfig and revtex macros, figures appended as uuencoded Postscript file (complete Postsript version including figures available via anonymous ftp from ftp://max.physics.sunysb.edu/preprints/harris/paper.ps.Z), ITP-SB-94-3