Threshold Resummation for Dark-Matter Production at the LHC

We derive precision predictions for the production of dark-matter particles recoiling against a jet with large transverse momentum at the LHC. The dark-matter fermions are described within a simplified model and couple to the Standard Model via a vector mediator. Our predictions for the mono-jet signature include the resummation of the leading and next-to-leading threshold logarithms. The corresponding matching coefficient is evaluated at NLO. The resummed result is matched to the fixed-order NLO cross section obtained from the MadGraph framework. We discuss numerical results for several benchmark scenarios at the LHC.Comment: 19 pages, 3 figure

Theoretical study of structural and optical properties of noble metal cluster–dipeptide hybrids at defect centers of MgO

We present the theoretical investigation of structural and optical properties of silver and gold cluster–dipeptide hybrids bound to the FS defect of the MgO (100) surface. We use DFT and its TDDFT variant combined with the polarizable embedded cluster model for the description of the extended MgO environment. As model peptide we have chosen CysTrp since the cysteine residue interacts strongly with metal particles through the sulfur atom and tryptophan is the most important chromophoric amino acid. Our results show that in the case of CysTrp bound to the supported Ag4 cluster an intense optical signal arises at 400 nm. In contrast, in the case of gold no strongly localized absorption is present since the optical response of supported gold–peptide hybrids is dominated by a large number of low intensity d-electron excitations spread over a broad energy range. Such a localized optical signal which is present in supported silver hybrids can be exploited for the optical detection of peptides and thus can serve as basis for the development of biosensing materials

Jet properties from di-hadron correlations in p+p collisions at s**(1/2) = 200-GeV

An analysis of high pT hadron spectra associated with high pT $\pi^0$ particles in p+p collisions at s**(1/2) = 200-GeV is presented. The shape of the azimuthal angular correlation is used to determine the value of partonic intrinsic momentum \sqrt{\left} = 2.68 \pm 0.07(\rm stat) \pm 0.34(\rm sys) GeV/c. The effect of kT-smearing of inclusive $\pi^0$ cross section is discussed.Comment: To appear in the proceedings of 2nd International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions (Hard Probes 2006), Asilomar, Pacific Grove, California, 9-16 Jun 200

High speed development of new chemical synthesis and materials at molecular-level: Methods and approaches

Recent success of advanced computational chemistry, in example for the prediction of chemical reactivity and materials properties, reflects its reputation as a valuable and widely accepted means to tackle problems in academia. The development of new simulation methods and new computer architectures enables an enormous improvement of the productivity of research and development of new chemical synthesisand materials. These advances can be achieved in terms of less time, material, and staff compared to traditional lab experiments. Especially, approaches like virtual high throughput screenings (vHTS) are highly scalable and allow fast and deep insights into new promising system modifications. Consequently, the time to market and risk of new product development can be decreased significantly. These characteristicspaved the way for the successful application in industry nowadays

A Phase I Trial of Aminolevulinic Acid-Photodynamic Therapy for Treatment of Oral Leukoplakia

Background Photodynamic therapy with aminolevulinic acid (ALA PDT) for oral leukoplakia has shown promising effects in regression of oral leukoplakia. Although ALA has been extensively studied and is an ideal photosensitizer, the optimal light dose for treatment of oral leukoplakia has not been determined. We conducted a phase I study to determine MTD and DLT of PDT in patients treated with ALA for leukoplakia. Methods Patients with histologically confirmed oral leukoplakia received a single treatment of ALA PDT in cohorts with escalating doses of light (585 nm). Clinical, histologic, and biologic markers were assessed. Results Analysis of 11 participants is reported. No significant toxicity from ALA PDT was observed in patients who received ALA with a light dose of up to 4 J/cm2. One participant experienced transient grade 3 transaminase elevation due to ALA. One participant had a partial clinical response 3 months after treatment. Biologic mucosal risk markers showed no significant associations. Determination of MTD could not be accomplished within a feasible timeframe for completion of the study. Conclusions ALA PDT could be safely administered with a light dose up to 4 J/cm2 and demonstrated activity. Larger studies are needed to fully elucidate the MTD and efficacy of ALA-PDT

Ag31(SG)19 and Ag15(SG)11

We report a simple synthesis of silver:glutathione (Ag:SG) clusters using a cyclic reduction under oxidative conditions. Two syntheses are described which lead to solutions containing well-defined Ag31(SG)19 and Ag15(SG)11 clusters that have been characterized by mass spectrometry. The optical properties of silver:glutathione (Ag:SG) cluster solutions have been investigated experimentally. In particular, the solution containing Ag15(SG)11 clusters shows a bright and photostable emission. For Ag31(SG)19 and Ag15(SG)11 clusters, the comparison of experimental findings with DFT and TDDFT calculations allowed us to reveal the structural and electronic properties of such low nuclearity liganded silver clusters

Ag31(SG)19 and Ag15(SG)11

We report a simple synthesis of silver:glutathione (Ag:SG) clusters using a cyclic reduction under oxidative conditions. Two syntheses are described which lead to solutions containing well-defined Ag31(SG)19 and Ag15(SG)11 clusters that have been characterized by mass spectrometry. The optical properties of silver:glutathione (Ag:SG) cluster solutions have been investigated experimentally. In particular, the solution containing Ag15(SG)11 clusters shows a bright and photostable emission. For Ag31(SG)19 and Ag15(SG)11 clusters, the comparison of experimental findings with DFT and TDDFT calculations allowed us to reveal the structural and electronic properties of such low nuclearity liganded silver clusters

Chemical shifts and cluster structure

The 2p core-level electron binding energies of size-selected silicon cluster ions have been determined from soft x-ray photoionization efficiency curves. Local chemical shifts and global charging energy contributions to the 2p binding energy can be separated, because core-level and valence-band electron binding energies exhibit the same inverse radius dependence. The experimental 2p binding energy distributions show characteristic size-specific patterns that are well reproduced by the corresponding electronic density of states obtained from density functional theory modeling. These results demonstrate that 2p binding energies in silicon clusters are dominated by initial state effects, i.e., by the interaction with the local valence electron density, and can thus be used to corroborate structural assignments

Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using √s=8 TeV proton-proton collision data

A search for squarks and gluinos in final states containing high-p T jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in s√=8 TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 20.3 fb−1. Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1330 GeV for a simplified model incorporating only a gluino and the lightest neutralino. For a simplified model involving the strong production of first- and second-generation squarks, squark masses below 850 GeV (440 GeV) are excluded for a massless lightest neutralino, assuming mass degenerate (single light-flavour) squarks. In mSUGRA/CMSSM models with tan β = 30, A 0 = −2m 0 and μ > 0, squarks and gluinos of equal mass are excluded for masses below 1700 GeV. Additional limits are set for non-universal Higgs mass models with gaugino mediation and for simplified models involving the pair production of gluinos, each decaying to a top squark and a top quark, with the top squark decaying to a charm quark and a neutralino. These limits extend the region of supersymmetric parameter space excluded by previous searches with the ATLAS detector