2,006 research outputs found
Novel observables for exploring QCD collective evolution and quantum entanglement within individual jets
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
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
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 collisions at 91 GeV with ALEPH archived data
Measurements of two-particle angular correlations of charged particles
emitted in hadronic decays are presented. The archived
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 pair from 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-k jet spectra and jet substructure using the archived ALEPH data at 91.2 GeV
We present the first anti-k jet spectrum and substructure measurements
using the archived ALEPH data taken in 1994 at a center of mass energy
of GeV. Jets are reconstructed with the anti-k
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
Long-range near-side correlation in Collisions at 183-209 GeV with ALEPH Archived Data
The first measurement of two-particle angular correlations for charged
particles produced in annihilation up to GeV with
LEP-II data is presented. Hadronic data, archived at center-of-mass
energies ranging from 183 to 209 GeV, were collected using the ALEPH detector
at LEP. The angular correlation functions have been measured across a wide
range of pseudorapidities and the full azimuth in bins of charged particle
multiplicity. Results for data at high energies, which allow for
higher event multiplicities reaching approximately 50 than LEP-I at Z pole
energy, are presented for the first time. A long-range near-side excess in the
correlation function has been identified in the analysis when calculating
particle kinematic variables with respect to the thrust axis. Moreover, the
two-particle correlation functions were decomposed using a Fourier series, and
the resulting Fourier coefficients were compared with event generator
outputs. In events with high multiplicity featuring more than 50 particles, the
extracted magnitude from the data are compared to those from the Monte
Carlo reference.Comment: Updated Figure 3 with ALICE publication To be submitted to PR
Genome sequencing with gene panel-based analysis for rare inherited conditions in a publicly funded healthcare system: implications for future testing
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
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, μ, 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 μ < 4.2 (3.3), corresponding to a best fit value [^ over μ] = 1.2[+1.6 over −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
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 non‐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 counselors’ roles in risk assessment, education, supervision, conducting research and presenting research options to patients. With PBCs serving as the pre‐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 Force’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 tτ channel in proton-proton collisions at √s = 8 TeV
A search for pair production of third-generation scalar leptoquarks decaying to top quark and τ lepton pairs is presented using proton-proton collision data at a center-of-mass energy of √s = 8 TeV collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 fb[superscript −1]. The search is performed using events that contain an electron or a muon, a hadronically decaying τ 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 τ lepton, the existence of pair produced, charge −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 τ lepton, and may also be applied directly to the pair production of bottom squarks decaying predominantly via the R-parity violating coupling λ [subscript 333] ′.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 √s = 13 TeV
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 35.9 fb⁻¹, 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 λ′′312 or λ′′323 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 ˜t→qq′ scenario
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