25 research outputs found
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The CMS dataset bookkeeping service
The CMS Dataset Bookkeeping Service (DBS) has been developed to catalog all CMS event data from Monte Carlo and Detector sources. It provides the ability to identify MC or trigger source, track data provenance, construct datasets for analysis, and discover interesting data. CMS requires processing and analysis activities at various service levels and the DBS system provides support for localized processing or private analysis, as well as global access for CMS users at large. Catalog entries can be moved among the various service levels with a simple set of migration tools, thus forming a loose federation of databases. DBS is available to CMS users via a Python API, Command Line, and a Discovery web page interfaces. The system is built as a multi-tier web application with Java servlets running under Tomcat, with connections via JDBC to Oracle or MySQL database backends. Clients connect to the service through HTTP or HTTPS with authentication provided by GRID certificates and authorization through VOMS. DBS is an integral part of the overall CMS Data Management and Workflow Management systems
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Holographic Systematics of D-brane Inflation
We provide a systematic treatment of possible corrections to the inflaton potential for D-brane inflation in the warped deformed conifold. We consider the D3-brane potential in the presence of the most general possible corrections to the throat geometry sourced by coupling to the bulk of a compact Calabi-Yau space. This corresponds to the potential on the Coulomb branch of the dual gauge theory, in the presence of arbitrary perturbations of the Lagrangian. The leading contributions arise from perturbations by the most relevant operators that do not destroy the throat geometry. We find a generic contribution from a non-chiral operator of dimension {Delta} = 2 associated with a global symmetry current, resulting in a negative contribution to the inflaton mass-squared. If the Calabi-Yau preserves certain discrete symmetries, this is the dominant correction to the inflaton potential, and fine-tuning of the inflaton mass is possible. In the absence of such discrete symmetries, the dominant contribution comes from a chiral operator with {Delta} = 3/2, corresponding to a {phi}{sup 3/2} term in the inflaton potential. The resulting inflationary models are phenomenologically identical to the inflection point scenarios arising from specific D7-brane embeddings, but occur under far more general circumstances. Our strategy extends immediately to other warped geometries, given sufficient knowledge of the Kaluza-Klein spectrum
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Electropolishing on small samples at Fermilab
The electropolishing process (EP) is considered an essential step in the processing of high gradient SRF cavities. Studies on EP of small samples has been started at Fermilab as part of the SRF materials R&D program. A simple bench top setup was developed to understand the basic variables affecting the EP. In addition a setup for vertical EP of half cells, based on the Cornell design, was used and another one for dumbbells was designed and tested. Results and findings are reported
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Magnetic Hydrogen Atmosphere Models and the Neutron Star RX J1856.5-3754
RX J1856.5-3754 is one of the brightest nearby isolated neutron stars, and considerable observational resources have been devoted to it. However, current models are unable to satisfactorily explain the data. We show that our latest models of a thin, magnetic, partially ionized hydrogen atmosphere on top of a condensed surface can fit the entire spectrum, from X-rays to optical, of RX J1856.5-3754, within the uncertainties. In our simplest model, the best-fit parameters are an interstellar column density N{sub H} {approx} 1 x 10{sup 20} cm{sup -2} and an emitting area with R{sup {infinity}} {approx} 17 km (assuming a distance to RX J1856.5-3754 of 140 pc), temperature T{sup {infinity}} {approx} 4.3 x 10{sup 5} K, gravitational redshift z{sub g} {approx} 0.22, atmospheric hydrogen column y{sub H} {approx} 1 g cm{sup -2}, and magnetic field B {approx} (3-4) x 10{sup 12} G; the values for the temperature and magnetic field indicate an effective average over the surface. We also calculate a more realistic model, which accounts for magnetic field and temperature variations over the neutron star surface as well as general relativistic effects, to determine pulsations; we find there exist viewing geometries that produce pulsations near the currently observed limits. The origin of the thin atmospheres required to fit the data is an important question, and we briefly discuss mechanisms for producing these atmospheres. Our model thus represents the most self-consistent picture to date for explaining all the observations of RX J1856.5-3754
Report of the 2005 Snowmass Top/QCD Working Group
This report discusses several topics in both top quark physics and QCD at an
International Linear Collider (ILC). Issues such as measurements at the
threshold, including both theoretical and machine requirements, and
the determination of electroweak top quark couplings, are reviewed. New results
concerning the potential of a 500 GeV collider for measuring
couplings and the top quark Yukawa coupling are presented. The status of higher
order QCD corrections to jet production cross sections, heavy quark form
factors, and longitudinal gauge boson scattering, needed for percent-level
studies at the ILC, are reviewed. A new study of the measurement of the
hadronic structure of the photon at a collider is presented. The
effects on top quark properties from several models of new physics, including
composite models, Little Higgs theories, and CPT violation, are studied.Comment: 39 pages, many figs; typos fixed and refs added. Contributed to the
2005 International Linear Collider Physics and Detector Workshop and 2nd ILC
Accelerator Workshop, Snowmass, Colorado, 14-27 Aug 200
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Challenges and concepts for design of an interaction region with push-pull arrangement of detectors - an interface document
Two experimental detectors working in a push-pull mode has been considered for the Interaction Region of the International Linear Collider [1]. The push-pull mode of operation sets specific requirements and challenges for many systems of detector and machine, in particular for the IR magnets, for the cryogenics and alignment system, for beamline shielding, for detector design and overall integration, and so on. These challenges and the identified conceptual solutions discussed in the paper intend to form a draft of the Interface Document which will be developed further in the nearest future. The authors of the present paper include the organizers and conveners of working groups of the workshop on engineering design of interaction region IRENG07 [2], the leaders of the IR Integration within Global Design Effort Beam Delivery System, and the representatives from each detector concept submitting the Letters Of Intent
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ECR plasma cleaning: an in-situ processing technique for RF cavities
A condition for Electron Cyclotron Resonance (ECR) can be established inside a fully assembled RF cavity without the need for removing high-power couplers. As such, plasma generated by this process can be used as a final cleaning step, or as an alternative cleaning step in place of other techniques. Tests showed filtered dry air plasma can successfully remove sulfur particles on niobium surface while the surface oxygen content remains intact
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Observation of Polarized Positrons from an Undulator-Based Source
An experiment (E166) at the Stanford Linear Accelerator Center (SLAC) has demonstrated a scheme in which a multi-GeV electron beam passed through a helical undulator to generate multi-MeV, circularly polarized photons which were then converted in a thin target to produce positrons (and electrons) with longitudinal polarization above 80% at 6 MeV. The results are in agreement with Geant4 simulations that include the dominant polarization-dependent interactions of electrons, positrons and photons in matter
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Oscillations in the CMB from Axion Monodromy Inflation
We study the CMB observables in axion monodromy inflation. These well-motivated scenarios for inflation in string theory have monomial potentials over super-Planckian field ranges, with superimposed sinusoidal modulations from instanton effects. Such periodic modulations of the potential can drive resonant enhancements of the correlation functions of cosmological perturbations, with characteristic modulations of the amplitude as a function of wavenumber. We give an analytical result for the scalar power spectrum in this class of models, and we determine the limits that present data places on the amplitude and frequency of modulations. Then, incorporating an improved understanding of the realization of axion monodromy inflation in string theory, we perform a careful study of microphysical constraints in this scenario. We find that detectable modulations of the scalar power spectrum are commonplace in well-controlled examples, while resonant contributions to the bispectrum are undetectable in some classes of examples and detectable in others. We conclude that resonant contributions to the spectrum and bispectrum are a characteristic signature of axion monodromy inflation that, in favorable cases, could be detected in near-future experiments
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Rare B meson decays at the Tevatron
Rare B meson decays are an excellent probe for beyond the Standard Model physics. Two very sensitive processes are the B{sub s,d}{sup 0} {yields} {mu}{sup +}{mu}{sup -} and b {yields} s{mu}{sup +}{mu}{sup -} decays. We report recent results at a center of mass energy of {radical}s = 1.96 TeV from the CDF II and D0 collaborations using between 3.7 fb{sup -1} and 6.9 fb{sup -1} taken during Run II of the Fermilab Tevatron Collider