1,686 research outputs found

    Novel observables for exploring QCD collective evolution and quantum entanglement within individual jets

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    We postulate that non-perturbative QCD effects occurring during parton fragmentation can result in collective effects of a multi-parton system, reminiscent of those observed in high-energy hadronic or nuclear interactions with large final-state particle multiplicity. Proton-proton collisions at the Large Hadron Collider showed surprising signatures of a strongly interacting, thermalized quark-gluon plasma, which was thought only to form in collisions of large nuclear systems. Another puzzle observed earlier in e+eāˆ’e^{+}e^{-} collisions is that production yields of various hadron species appear to follow a thermal-like distribution with a common temperature. We propose searches for thermal and collective properties resulting from parton fragmentation processes using high multiplicity jets in high-energy elementary collisions. Several novel observables are studied using the PYTHIA 8 Monte Carlo event generator. Experimental observation of such collectivity will offer a new view of non-perturbative QCD dynamics of multi-parton systems at the smallest scales. Absence of any collective effects may offer new insights into the role of quantum entanglement in the observed thermal behavior of particle production in high energy collisions.Comment: 14 pages, 12 figures. Updated to mirror version accepted by journa

    Molecular Dynamics Simulation of the Transport Properties of Molten Transuranic Chloride Salts

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    The Accelerator Research Laboratory at Texas A&M is proposing a design for accelerator-driven subcritical fission in molten salt (ADSMS), a system that destroys the transuranic elements in used nuclear fuel. The transuranics (TRU) are the most enduring hazard of nuclear power. TRU contain high radiotoxicity and have half-lives of a thousand to a million years. The ADSMS core is fueled by a homogeneous chloride-based molten salt mixture containing TRUCl3 and NaCl. Certain thermodynamic properties are critical to modeling both the neutronics and heat transfer of an ADSMS system. There is a lack of experimental data on the density, heat capacity, electrical and thermal conductivities, and viscosity of TRUCl3 salt systems. Molecular dynamics simulations using a polarizable ion model (PIM) are employed to determine the density and heat capacity of these melts as a function of temperature. Green-Kubo methods are implemented to calculate the electrical conductivity, thermal conductivity, and viscosity of the salt using the outputs of the simulations. Results for pure molten salt systems are compared to experimental data when possible to validate the potentials used. Here I discuss chloride salt systems of interest, their calculated properties, and possible sources of error for our simulations

    Measurements of two-particle correlations in e+eāˆ’e^+e^- collisions at 91 GeV with ALEPH archived data

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    Measurements of two-particle angular correlations of charged particles emitted in hadronic ZZ decays are presented. The archived e+eāˆ’e^+e^- annihilation data at a center-of-mass energy of 91 GeV were collected with the ALEPH detector at LEP between 1992 and 1995. The correlation functions are measured over a broad range of pseudorapidity and full azimuth as a function of charged particle multiplicity. No significant long-range correlation is observed in either the lab coordinate analysis or the thrust coordinate analysis, where the latter is sensitive to a medium expanding transverse to the color string between the outgoing qqĖ‰q\bar{q} pair from ZZ boson decays. The associated yield distributions in both analyses are in better agreement with the prediction from the PYTHIA v6.1 event generator than from HERWIG v7.1.5. They provide new insights to showering and hadronization modeling. These results serve as an important reference to the observed long-range correlation in proton-proton, proton-nucleus, and nucleus-nucleus collisions.Comment: Replaced with the published version. Added the journal reference and the DO

    First measurement of anti-kT_\mathrm{T} jet spectra and jet substructure using the archived ALEPH e+eāˆ’e^+e^- data at 91.2 GeV

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    We present the first anti-kT_{T} jet spectrum and substructure measurements using the archived ALEPH e+eāˆ’e^+e^- data taken in 1994 at a center of mass energy of s=91.2\sqrt{s} = 91.2 GeV. Jets are reconstructed with the anti-kT_{T} algorithm with a resolution parameter of 0.4. It is the cleanest test of jets and QCD without the complication of hadronic initial states. The fixed center-of-mass energy also allows the first direct test of pQCD calculation. We present both the inclusive jet energy spectrum and the leading dijet energy spectra, together with a number of substructure observables. They are compared to predictions from PYTHIA6, PYTHIA8, Sherpa, HERWIG, VINCIA, and PYQUEN. None of the models fully reproduce the data. The data are also compared to two perturbative QCD calculations at NLO and with NLL'+R resummation. The results can also serve as reference measurements to compare to results from hadronic colliders. Future directions, including testing jet clustering algorithms designed for future electron-ion collider experiments, will also be discussed

    Genome sequencing with gene panel-based analysis for rare inherited conditions in a publicly funded healthcare system: implications for future testing

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    Acknowledgements This study would not be possible without the families, patients, clinicians, nurses, research scientists, laboratory staff, informaticians and the wider Scottish Genomes Partnership team to whom we give grateful thanks. This research was made possible through access to the data and findings generated by the 100,000 Genomes Project. The 100,000 Genomes Project is managed by Genomics England Limited (a wholly owned company of the Department of Health). The Scottish Genomes Partnership was funded by the Chief Scientist Office of the Scottish Government Health Directorates (SGP/1) and The Medical Research Council Whole Genome Sequencing for Health and Wealth Initiative (MC/PC/15080). The 100,000 Genomes Project is funded by the National Institute for Health Research and NHS England. The Wellcome Trust, Cancer Research UK and the Medical Research Council have also funded research infrastructure.Peer reviewedPublisher PD

    Search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks using a matrix element method

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    A search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks is presented. Events with hadronic jets and one or two oppositely charged leptons are selected from a data sample corresponding to an integrated luminosity of 19.5 fb[superscript -1] collected by the CMS experiment at the LHC in pp collisions at a centre-of-mass energy of 8 TeV. In order to separate the signal from the larger t[bar over t] + jets background, this analysis uses a matrix element method that assigns a probability density value to each reconstructed event under signal or background hypotheses. The ratio between the two values is used in a maximum likelihood fit to extract the signal yield. The results are presented in terms of the measured signal strength modifier, Ī¼, relative to the standard model prediction for a Higgs boson mass of 125 GeV. The observed (expected) exclusion limit at a 95 % confidence level is Ī¼ < 4.2 (3.3), corresponding to a best fit value [^ over Ī¼] = 1.2[+1.6 over āˆ’1.5].United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

    2013 Review and Update of the Genetic Counseling Practice Based Competencies by a Task Force of the Accreditation Council for Genetic Counseling

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    The first practice based competencies (PBCs) for the field of genetic counseling were adopted by the American Board of Genetic Counseling (ABGC), 1996. Since that time, there has been significant growth in established and new work settings (clinical and nonā€clinical) and changes in service delivery models and the roles of genetic counselors. These changes prompted the ABGC to appoint a PBC Task Force in 2011 to review the PBCs with respect to their current relevance and to revise and update them as necessary. There are four domains in the revised PBCs: (I) Genetics Expertise and Analysis (II) Interpersonal, Psychosocial and Counseling Skills (III) Education and (IV) Professional Development and Practice. There are 22 competencies, each clarified with learning objectives or samples of activities and skills; a glossary is included. New competencies were added that address genomics, genetic testing and genetic counselorsā€™ roles in risk assessment, education, supervision, conducting research and presenting research options to patients. With PBCs serving as the preā€defined abilities or outcomes of training, graduating genetic counselors will be well prepared to enter the field with a minimum level of skills and abilities. A description of the Task Forceā€™s work, key changes and the 2013 PBCs are presented herein.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147172/1/jgc40868.pd

    Search for third-generation scalar leptoquarks in the tĻ„ channel in proton-proton collisions at āˆšs = 8 TeV

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    A search for pair production of third-generation scalar leptoquarks decaying to top quark and Ļ„ lepton pairs is presented using proton-proton collision data at a center-of-mass energy of āˆšs = 8 TeV collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 fb[superscript āˆ’1]. The search is performed using events that contain an electron or a muon, a hadronically decaying Ļ„ lepton, and two or more jets. The observations are found to be consistent with the standard model predictions. Assuming that all leptoquarks decay to a top quark and a Ļ„ lepton, the existence of pair produced, charge āˆ’1/3, third-generation leptoquarks up to a mass of 685 GeV is excluded at 95% confidence level. This result constitutes the first direct limit for leptoquarks decaying into a top quark and a Ļ„ lepton, and may also be applied directly to the pair production of bottom squarks decaying predominantly via the R-parity violating coupling Ī» [subscript 333] ā€².United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

    Search for Pair-Produced Resonances Decaying to Quark Pairs in Proton-Proton Collisions at āˆšs = 13ā€‰ā€‰TeV

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    A general search for the pair production of resonances, each decaying to two quarks, is reported. The search is conducted separately for heavier resonances (masses above 400 GeV), where each of the four final-state quarks generates a hadronic jet resulting in a four-jet signature, and for lighter resonances (masses between 80 and 400 GeV), where the pair of quarks from each resonance is collimated and reconstructed as a single jet resulting in a two-jet signature. In addition, a b-tagged selection is applied to target resonances with a bottom quark in the final state. The analysis uses data collected with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 35.9ā€‰ā€‰fbā»Ā¹, from proton-proton collisions at a center-of-mass energy of 13 TeV. The mass spectra are analyzed for the presence of new resonances, and are found to be consistent with standard model expectations. The results are interpreted in the framework of R-parity-violating supersymmetry assuming the pair production of scalar top quarks decaying via the hadronic coupling Ī»ā€²ā€²312 or Ī»ā€²ā€²323 and upper limits on the cross section as a function of the top squark mass are set. These results probe a wider range of masses than previously explored at the LHC, and extend the top squark mass limits in the Ėœtā†’qqā€² scenario

    Search for electroweak production of charginos and neutralinos in multilepton final states in proton-proton collisions at āˆšs = 13 TeV

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    Results are presented from a search for the direct electroweak production of charginos and neutralinos in signatures with either two or more leptons (electrons or muons) of the same electric charge, or with three or more leptons, which can include up to two hadronically decaying tau leptons. The results are based on a sample of proton-proton collision data collected at sāˆš=13 TeV, recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9 fbā»Ā¹. The observed event yields are consistent with the expectations based on the standard model. The results are interpreted in simplified models of supersymmetry describing various scenarios for the production and decay of charginos and neutralinos. Depending on the model parameters chosen, mass values between 180 GeV and 1150 GeV are excluded at 95% CL. These results significantly extend the parameter space probed for these particles in searches at the LHC. In addition, results are presented in a form suitable for alternative theoretical interpretations
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