3,173 research outputs found

    Next-to-leading order QCD corrections to a heavy resonance production and decay into top quark pair at the LHC

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    We present a complete next-to-leading order (NLO) QCD calculation to a heavy resonance production and decay into a top quark pair at the LHC, where the resonance could be either a Randall-Sundrum (RS) Kaluza-Klein (KK) graviton GG or an extra gauge boson Z′Z'. The complete NLO QCD corrections can enhance the total cross sections by about 80%−100%80\%- 100\% and 20%−40%20\%- 40\% for the GG and the Z′Z', respectively, depending on the resonance mass. We also explore in detail the NLO corrections to the polar angle distributions of the top quark, and our results show that the shapes of the NLO distributions can be different from the leading order (LO) ones for the KK graviton. Moreover, we study the NLO corrections to the spin correlations of the top quark pair production via the above process, and find that the corrections are small.Comment: Published version in PR

    Precise QCD predictions on top quark pair production mediated by massive color octet vector boson at hadron colliders

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    We present a theoretical framework for systematically calculating next-to-leading order (NLO) QCD effects to various experimental observables in models with massive COVB in a model independent way at hadron colliders. Specifically, we show the numerical results for the NLO QCD corrections to total cross sections, invariant mass distribution and AFB of top quark pairs production mediated by a massive COVB in both the fixed scale (top quark mass) scheme and the dynamical scale (top pair invariant mass) scheme. Our results show that the NLO QCD calculations in the dynamical scale scheme is more reasonable than the fixed scheme and the naive estimate of the NLO effects by simple rescaling of the LO results with the SM NLO K-factor is not appropriate.Comment: 6 pages, 5 figures, 2 tables; version published in EPJ

    One-loop Helicity Amplitudes for Top Quark Pair Production in Randall-Sundrum Model

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    In this paper, we show how to calculate analytically the one-loop helicity amplitudes for the process qqˉrightarrowttˉq\bar{q} rightarrow t\bar{t} induced by KK gluon, using the spinor-helicity formalism. A minimal set of Feynman rules which are uniquely fixed by gauge invariance and the color representation of the KK gluon are derived and used in the calculation. Our results can be applied to a variety of models containing a massive color octet vector boson.Comment: 37 pages, 10 figures, journal versio

    QCD Effects in High Energy Processes

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    In this talk, some important QCD effects in Higgs physics, supersymmetry and top physics, as well as the factorization and resummation techniques in QCD are reviewed.Comment: LaTeX, 13 pages, uses ws-ijmpa.cls. Based on an invited talk at the International Conference on QCD and Hadronic Physics, Beijing, China, June 16--20, 2005. Minor change

    Next-to-leading order QCD corrections to the top quark decay via the Flavor-Changing Neutral-Current operators with mixing effects

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    In this paper detailed calculations of the complete O(αs)\mathcal{O}(\alpha_s) corrections to top quark decay widths Γ(t→q+V)\Gamma(t\to q+V) are presented (V=g,γ,ZV=g,\gamma,Z). Besides describing in detail the calculations in our previous paper (arXiv:0810.3889), we also include the mixing effects of the Flavor-Changing Neutral-Current (FCNC) operators for t→q+γt\to q+\gamma and t→q+Zt\to q+Z, which were not considered in our previous paper. The results for t→q+gt\to q+g are the same as in our previous paper. But the mixing effects can either be large or small, and increase or decrease the branching ratios for t→q+γt\to q+\gamma and t→q+Zt\to q+Z, depending on the values of the anomalous couplings (κtqg,γ,Z/Λ\kappa^{g,\gamma,Z}_{\mathrm{tq}}/\Lambda, ftqg,γ,Zf^{g,\gamma,Z}_{\mathrm{tq}} and htqg,γ,Zh^{g,\gamma,Z}_{\mathrm{tq}}).Comment: 21 pages, 12 figure

    Comparison of the Efficacy of MOE and PMO Modifications of Systemic Antisense Oligonucleotides in a Severe SMA Mouse Model

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    Spinal muscular atrophy (SMA) is a motor neuron disease. Nusinersen, a splice-switching antisense oligonucleotide (ASO), was the first approved drug to treat SMA. Based on prior preclinical studies, both 2'-O-methoxyethyl (MOE) with a phosphorothioate backbone and morpholino with a phosphorodiamidate backbone-with the same or extended target sequence as nusinersen-displayed efficient rescue of SMA mouse models. Here, we compared the therapeutic efficacy of these two modification chemistries in rescue of a severe mouse model using ASO10-29-a 2-nt longer version of nusinersen-via subcutaneous injection. Although both chemistries efficiently corrected SMN2 splicing in various tissues, restored motor function and improved the integrity of neuromuscular junctions, MOE-modified ASO10-29 (MOE10-29) was more efficacious than morpholino-modified ASO10-29 (PMO10-29) at the same molar dose, as seen by longer survival, greater body-weight gain and better preservation of motor neurons. Time-course analysis revealed that MOE10-29 had more persistent effects than PMO10-29. On the other hand, PMO10-29 appears to more readily cross an immature blood-brain barrier following systemic administration, showing more robust initial effects on SMN2 exon 7 inclusion, but less persistence in the central nervous system. We conclude that both modifications can be effective as splice-switching ASOs in the context of SMA and potentially other diseases, and discuss the advantages and disadvantages of each

    Experimental realization of large-alphabet quantum key distribution protocol using orbital angular momentum entanglement

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    We experimentally demonstrate a quantum key distribution (QKD) protocol using photon pairs entangled in orbit angular momentum (OAM). In our protocol, Alice and Bob modulate their OAM states on each entangled pair with spatial light modulators (SLMs), respectively. Alice uses a fixed phase hologram in her SLM, while Bob designs NN different suitable phase holograms and uses them to represent his NN-based information in his SLM. With coincidences, Alice can fully retrieve the key stream sent by Bob without information reconciliation or privacy amplification. We report the experiment results with N=3 and the sector states with OAM eigenmodes l=1 and l=-1. Our experiment shows that the coincidence rates are in relatively distinct value regions for the three different key elements. Alice could recover fully Bob's keys by the protocol. Finally, we discuss the security of the protocol both form the light way and against the general attacks

    Characterisation of volatile components of red and sparkling wines from a new wine grape cultivar 'Meili' (Vitis vinifera L.)

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    'Meili' (Vitis vinifera L.) is a new wine grape cultivar from China. Volatile profiles of red and sparkling wines made from 'Meili' grapes were analysed using stir bar sorptive extraction-gas chromatography-mass spectrometry in this study. Fiftyfive volatile compounds were quantified in both wines, and quantitative differences for most of the volatile compounds between 'Meili' wines were observed. 'Meili' sparkling wine had a greater content of esters, fatty acids and shikimic acid derivatives than 'Meili' red wine, although 'Meili' red wine had higher concentrations of alcohols, terpenoids and C13-norisoprenoids. On the basis of odour activity values, ethyl acetate, ethyl butanoate, ethyl hexanoate, ethyl octanoate, isoamyl acetate, ethyl 2-methylpropanoate, ethyl 3-methylbutanoate, octanoic acid, isoamyl alcohol, 2-phenyl ethanol, linalool, β-damascenone and β-ionone were considered as important aroma compounds in 'Meili' wines. For these compounds, 'Meili' sparkling wine had higher content of ethyl acetate, ethyl butanoate, ethyl hexanoate, ethyl octanoate and isoamyl acetate than 'Meili' red wine, while 'Meili' red wine had higher levels of isoamyl alcohol, 2-phenylethanol, linalool, β-damascenone and β-ionone. The concentration differences of aroma compounds due to the differential vinification procedures suggested the differences in sensory characteristics of the two types of wines. In particular, 'Meili' red wine had more rose aroma than 'Meili' sparkling wine.
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