PICMG xTCA Standards Extensions for Physics: New Developments & Future Plans (open access)

PICMG xTCA Standards Extensions for Physics: New Developments & Future Plans

After several years of planning and workshop meetings, a decision was reached in late 2008 to organize PICMG xTCA for Physics Technical Subcommittees to extend the ATCA and MTCA telecom standards for enhanced system performance, availability and interoperability for physics controls and applications hardware and software. Since formation in May-June 2009, the Hardware Technical Subcommittee has developed a number of ATCA, ARTM, AMC, MTCA and RTM extensions to be completed in mid-to-late 2010. The Software Technical Subcommittee is developing guidelines to promote interoperability of modules designed by industry and laboratories, in particular focusing on middleware and generic application interfaces such as Standard Process Model, Standard Device Model and Standard Hardware API. The paper describes the prototype design work completed by the lab-industry partners to date, the timeline for hardware releases to PICMG for approval, and the status of the software guidelines roadmap. The paper also briefly summarizes the program of the 4th xTCA for Physics Workshop immediately preceding the RT2010 Conference. he case for developing ATCA and MicroTCA (xTCA) specification extensions for physics has been covered in several previous papers. Briefly, ATCA and MicroTCA is the first all-serial communication platform available to the physics community to support both massively complex …
Date: August 26, 2010
Creator: Larsen, R.S.
Object Type: Article
System: The UNT Digital Library
Lessons Learned from PEP-II LLRF and Longitudinal Feedback (open access)

Lessons Learned from PEP-II LLRF and Longitudinal Feedback

The PEP-II B-Factory collider ended the final phase of operation at nearly twice the design current and 4X the design luminosity. To highlight the evolution from the original conceptual design through to the 1.2E34 final machine we choose one example each from the broadband feedback and from the LLRF system. They illustrate the original design estimation missed some very significant details, and how in the course of PEP-II operation unexpected difficulties led to significant insights and new approaches which allowed higher machine performance. We present valuable 'lessons learned' which are of interest to designers of next generation feedback and impedance controlled LLRF systems.
Date: August 26, 2010
Creator: Fox, J. D.; Mastorides, T.; Rivetta, C. H.; Van Winkle, D. & Teytelman, D.
Object Type: Article
System: The UNT Digital Library
'Insightful D-branes' (open access)

'Insightful D-branes'

We study a simple model of a black hole in AdS and obtain a holographic description of the region inside the horizon. A key role is played by the dynamics of the scalar fields in the dual gauge theory. This leads to a proposal for a dual description of D-branes falling through the horizon of any AdS black hole. The proposal uses a field-dependent time reparameterization in the field theory. We relate this reparametrization to various gauge invariances of the theory. Finally, we speculate on information loss and the black hole singularity in this context.
Date: August 26, 2010
Creator: Horowitz, Gary; /UC, Santa Barbara; Lawrence, Albion; /Brandeis U. /Santa Barbara, KITP; Silverstein, Eva & /SLAC /Stanford U., Phys. Dept. /Santa Barbara, KITP
Object Type: Article
System: The UNT Digital Library
Status of CKM angle measurements, a report from BaBar and Belle (open access)

Status of CKM angle measurements, a report from BaBar and Belle

I will review the latest developments in determining the CP-violating phases of the CKM matrix elements from measurements by the BaBar and BELLE experiments at the high-luminosity B factories (PEP-II and KEKB). The emphasis will be on the angle {gamma}/{phi}{sub 3} of the Unitarity Triangle, which is the relative phase arg(-V{sub ud}V*{sub ub}/V{sub cd}V*{sub cb}), or the CP-violating phase of the b {yields} u transition in the commonly used Wolfenstein convention.
Date: August 26, 2010
Creator: Long, Owen & /UC, Riverside
Object Type: Article
System: The UNT Digital Library
Study of Higgs boson production and its b-b(bar) decay in gamma-gamma processes in proton-nucleus collisions at the LHC (open access)

Study of Higgs boson production and its b-b(bar) decay in gamma-gamma processes in proton-nucleus collisions at the LHC

We explore for the first time the possibilities to measure an intermediate-mass (m{sub H} = 115-140 GeV/c{sup 2}) Standard-Model Higgs boson in electromagnetic proton-lead (p Pb) interactions at the CERN Large Hadron Collider (LHC) via its b{bar b} decay. Using equivalent Weizsacker-Williams photon fluxes and Higgs effective field theory for the coupling {gamma}{gamma} {yields} H, we obtain a leading-order cross section of the order of 0.3 pb for exclusive Higgs production in elastic (p Pb {yields} {gamma}{gamma} p H Pb) and semielastic (p Pb {yields} {gamma}{gamma} X H Pb) processes at {radical}S{sub NN} = 8.8 TeV. After applying various kinematics cuts to remove the main backgrounds ({gamma}{gamma} {yields} b{bar b} and misidentified {gamma}{gamma} {yields} q{bar q} events), we find that a Higgs boson with m{sub H} = 120 GeV/c{sup 2} could be observed in the b{bar b} channel with a 3{sigma}-significance integrating 300 pb{sup -1} with an upgraded pA luminosity of 10{sup 31} cm{sup -2}s{sup -1}. We also provide for the first time semielastic Higgs cross sections, along with elastic t{bar t} cross sections, for electromagnetic pp, pA and AA collisions at the LHC.
Date: August 26, 2010
Creator: d'Enterria, David; /ICC, Barcelona U. /ICREA, Barcelona; Lansberg, Jean-Philippe & /Ecole Polytechnique, CPHT /SLAC
Object Type: Article
System: The UNT Digital Library
Touschek Background and Lifetime Studies for the SuperB Factory (open access)

Touschek Background and Lifetime Studies for the SuperB Factory

The novel crab waist collision scheme under test at the DA{Phi}NE Frascati {Phi}-factory finds its natural application to the SuperB project, the asymmetric e{sup +}e{sup -} flavour factory at very high luminosity with relatively low beam currents and reduced backgrounds. The SuperB accelerator design requires a careful choice of beam parameters to reach a good trade-off between different effects. We present here simulation results for the Touschek backgrounds and lifetime obtained for both the low and high energy rings for different machine designs. A first set of horizontal collimators has been studied to stop Touschek particles. A study of the distributions of the Touschek particle losses at the interaction region into the detectors for further investigations is underway.
Date: August 26, 2010
Creator: Boscolo, M.; Biagini, M.; Raimondi, P.; Sullivan, M. & Paoloni, E.
Object Type: Article
System: The UNT Digital Library
Parity Violation in Composite Inelastic Dark Matter Models (open access)

Parity Violation in Composite Inelastic Dark Matter Models

Recent experimental results indicate that the dark matter sector may have a non-minimal structure with a spectrum of states and interactions. Inelastic scattering has received particular attention in light of DAMA's annual modulation signal. Composite inelastic dark matter (CiDM) provides a dynamical origin for the mass splittings in inelastic dark matter models. We show that higher dimensional operators in the CiDM Lagrangian lead to an admixture of inelastic and elastic scattering in the presence of parity violation. This scenario is consistent with direct detection experiments, even when parity violation is nearly maximal. We present an effective field theory description of such models and discuss the constraints from direct detection experiments. The CiDM model with parity violation has non-trivial phenomenology because of the multiple scattering channels that are allowed.
Date: August 26, 2010
Creator: Lisanti, Mariangela & Wacker, Jay G.
Object Type: Article
System: The UNT Digital Library
Search for lepton flavor violating decay τ<sup>-</sup> →ℓ<sup>-</sup>ℓ<sup>+</sup>ℓ<sup>-</sup>ℓ = e, μ at BaBar (open access)

Search for lepton flavor violating decay τ<sup>-</sup> →ℓ<sup>-</sup>ℓ<sup>+</sup>ℓ<sup>-</sup>ℓ = e, μ at BaBar

The Standard Model (SM) is one of the most tested and verified physical theories of all time, present experimental observations are consistent with SM expectations. On the other hand SM can not explain many physical observations: the cosmological observations possibly infer the presence of dark matter which is clearly beyond the SM expectations; the SM Higgs model, while explaining the generation of fermion masses, can not explain the hierarchy problem and a non natural fine tuning of SM is needed to cancel out quadratic divergences in the Higgs boson mass. New physics (NP) beyond SM should hence be investigated: rising the energy above NP processes thresholds, and detecting new particles or new effects not predicted by the standard model directly, is one of the possible approaches; another approach is to make precision measurements of well known processes or looking for rare processes which involve higher order contribution from NP processes, this approach need higher luminosities with respect to the previous approach but lower beam energies. Search for Lepton Flavor Violation (LFV) in charged lepton decays is promising: neutrino physics provides indeed a clear and unambiguous evidence of LFV in the neutral lepton sector via mixing processes, which have been observed …
Date: May 26, 2010
Creator: Cervelli, Alberto
Object Type: Thesis or Dissertation
System: The UNT Digital Library
``Towards Strange Metallic Holography' (open access)

``Towards Strange Metallic Holography'

We initiate a holographic model building approach to 'strange metallic' phenomenology. Our model couples a neutral Lifshitz-invariant quantum critical theory, dual to a bulk gravitational background, to a finite density of gapped probe charge carriers, dually described by D-branes. In the physical regime of temperature much lower than the charge density and gap, we exhibit anomalous scalings of the temperature and frequency dependent conductivity. Choosing the dynamical critical exponent z appropriately we can match the non-Fermi liquid scalings, such as linear resistivity, observed in strange metal regimes. As part of our investigation we outline three distinct string theory realizations of Lifshitz geometries: from F theory, from polarized branes, and from a gravitating charged Fermi gas. We also identify general features of renormalization group flow in Lifshitz theories, such as the appearance of relevant charge-charge interactions when z {ge} 2. We outline a program to extend this model building approach to other anomalous observables of interest such as the Hall conductivity.
Date: August 26, 2010
Creator: Hartnoll, Sean A.; /Harvard U., Phys. Dept. /Santa Barbara, KITP /UC, Santa Barbara; Polchinski, Joseph; Silverstein, Eva; /Santa Barbara, KITP /UC, Santa Barbara; Tong, David et al.
Object Type: Article
System: The UNT Digital Library
Compact 400-Mhz Half-Wave Spoke Resonator Crab Cavity for the LHC Update (open access)

Compact 400-Mhz Half-Wave Spoke Resonator Crab Cavity for the LHC Update

Crab cavities are proposed for the LHC upgrade to improve the luminosity. There are two possible crab cavity installations for the LHC upgrade: the global scheme at Interaction Region (IR) 4 where the beam-beam separation is about 420-mm, and the local scheme at the IR5 where the beam-beam separation is only 194-mm. One of the design requirements as the result of a recent LHC-Crab cavity workshop is to develop a 400-MHz cavity design that can be utilized for either the global or local schemes at IR4 or IR5. Such a design would offer more flexibility for the final upgrade installation, as the final crabbing scheme is yet to be determined, and save R&amp;D cost. The cavity size of such a design, however, is limited by the beam-beam separation at IR5 which can only accommodate a cavity with a horizontal size of about 145-mm, which is a design challenge for a 400-MHz cavity. To meet the new design requirements, we have developed a compact 400-MHz half-wave spoke resonator (HWSR) crab cavity that can fit into the tight spaces available at either IR4 or IR5. In this paper, we present the optimization of the HWSR cavity shape and the design of HOM, …
Date: August 26, 2010
Creator: Li, Zenghai; Xiao, Liling; Ng, Cho & Markiewicz, Thomas
Object Type: Article
System: The UNT Digital Library
Cooling Coil Effects on Blending in a Pilot Scale Tank (open access)

Cooling Coil Effects on Blending in a Pilot Scale Tank

Blending, or mixing, processes in 1.3 million gallon nuclear waste tanks are complicated by the fact that miles of serpentine, vertical, cooling coils are installed in the tanks. As a step toward investigating blending interference due to coils in this type of tank, a 1/10.85 scale tank and pump model were constructed for pilot scale testing. A series of tests were performed in this scaled tank by adding blue dye to visualize blending, and by adding acid or base tracers to solution to quantify the time required to effectively blend the tank contents. The acid and base tests were monitored with pH probes, which were located in the pilot scale tank to ensure that representative samples were obtained. Using the probes, the hydronium ion concentration [H{sup +}] was measured to ensure that a uniform concentration was obtained throughout the tank. As a result of pilot scale testing, a significantly improved understanding of mixing, or blending, in nuclear waste tanks has been achieved. Evaluation of test data showed that cooling coils in the waste tank model increased pilot scale blending times by 200% in the recommended operating range, compared to previous theoretical estimates of a 10-50% increase. Below the planned operating …
Date: August 26, 2010
Creator: Leishear, R.; Poirier, M.; Fowley, M. & Steeper, T.
Object Type: Article
System: The UNT Digital Library
Supersymmetry Without (Too Much) Prejudice (open access)

Supersymmetry Without (Too Much) Prejudice

We have recently completed a detailed scan of the 19-dimensional parameter space of the phenomenological MSSM, i.e., the CP-conserving MSSM [Minimal Supersymmtric Standard Model] assuming Minimal Flavor Violation (MFV) with the first two sfermion generations degenerate. We found a large set of parameter space points that satisfied all of the existing experimental and theoretical constraints. This analysis allows us to examine the general features of the MSSM without reference to any particular SUSY breaking scenario or any other assumptions about physics at higher scales. This study opens up new possibilities for SUSY phenomenology both at colliders and in astrophysical observations.
Date: August 26, 2010
Creator: Rizzo, Thomas G.
Object Type: Article
System: The UNT Digital Library
Construction and Bench Testing of a Rotatable Collimator for the LHC Collimation Upgrade (open access)

Construction and Bench Testing of a Rotatable Collimator for the LHC Collimation Upgrade

The Phase II upgrade to the LHC collimation system calls for complementing the 30 high robust Phase I graphite secondary collimators with 30 high Z Phase II collimators. The Phase II collimators must be robust in various operating conditions and accident scenarios. This paper reports on the final construction and testing of the prototype collimator to be installed in the SPS (Super Proton Synchrotron) at CERN. Bench-top measurements will demonstrate that the device is fully operational and has the mechanical and vacuum characteristics acceptable for installation in the SPS.
Date: August 26, 2010
Creator: Smith, Jeffrey Claiborne; Keller, Lewis; Lundgren, Steven; Markiewicz, Thomas & /SLAC
Object Type: Article
System: The UNT Digital Library
Quantum Oscillations in the Parent pnictide BaFe2As2 : Itinerant Electrons in the Reconstructed State (open access)

Quantum Oscillations in the Parent pnictide BaFe2As2 : Itinerant Electrons in the Reconstructed State

We report quantum oscillation measurements that enable the direct observation of the Fermi surface of the low temperature ground state of BaFe{sub 2}As{sub 2}. From these measurements we characterize the low energy excitations, revealing that the Fermi surface is reconstructed in the antiferromagnetic state, but leaving itinerant electrons in its wake. The present measurements are consistent with a conventional band folding picture of the antiferromagnetic ground state, placing important limits on the topology and size of the Fermi surface.
Date: May 26, 2010
Creator: Analytis, J.G.
Object Type: Article
System: The UNT Digital Library
Transmission and Propagation of an Accelerating Mode in a Photonic Bandgap Fiber (open access)

Transmission and Propagation of an Accelerating Mode in a Photonic Bandgap Fiber

A hollow core photonic bandgap (PBG) lattice in a dielectric fiber can provide high gradient acceleration in the optical regime, where the accelerating mode resulting from a defect in the PBG fiber can be excited by high-power lasers. Efficient methods of coupling laser power into the PBG fiber are an area of active research. In this paper, we develop a simulation method using the parallel finite-element electromagnetic suite ACE3P to study the propagation of the accelerating mode in the PBG fiber and determine the radiation pattern into free space at the end of the PBG fiber. The far-field radiation will be calculated and the mechanism of coupling power from an experimental laser setup will be discussed.
Date: August 26, 2010
Creator: Ng, C. K.; England, R. J.; Lee, L. Q.; Noble, R.; Rawat, V. & Spencer, J.
Object Type: Article
System: The UNT Digital Library
Collective Quartics from Simple Groups (open access)

Collective Quartics from Simple Groups

This article classifies Little Higgs models that have collective quartic couplings. There are two classes of collective quartics: Special Cosets and Special Quartics. After taking into account dangerous singlets, the smallest Special Coset models are SU(5)/SO(5) and SU(6)/Sp(6). The smallest Special Quartic model is SU(5)/SU(3) x SU(2) x U(1) and has not previously been considered as a candidate Little Higgs model.
Date: August 26, 2010
Creator: Hook, Anson & Wacker, Jay G.
Object Type: Article
System: The UNT Digital Library
FERMI view of the TeV blazar Markarian 421 (open access)

FERMI view of the TeV blazar Markarian 421

The high energy component of the TeV blazar Markarian 421 has been extensively studied since the beginning of the 90s, when the source was first detected at gamma-rays with EGRET and the Whipple Telescope, yet the source is still far from being understood. The high sensitivity, large dynamic range, and excellent time coverage of the Fermi Large Area Telescope (LAT), all representing significant advances over previous gamma-ray observations, will play a key role in the elucidation of the physical processes underlying the high energy emission of this blazar. In this presentation we show the results from almost 6 months (4 August 2008 to 20 January 2009) of observation with LAT. We report significant flux/spectral variability on a range of time scales from weeks to days, and an energy spectrum from 0.1 GeV to 300 GeV, overlapping with the energy ranges covered by the current generation of Cherenkov Telescopes. Results on the observations of the BLLac object Markarian 421 collected in the first months of operation of the Fermi satellite have been presented. Light curves on weekly and daily timescales have been shown, as well as the results of the spectral analysis in the energy range between 100 MeV and 300 …
Date: August 26, 2010
Creator: Paneque, D; /SLAC /KIPAC, Menlo Park; Raino, S.; /Bari Polytechnic /INFN, Bari; Chiang, J.; /SLAC /KIPAC, Menlo Park et al.
Object Type: Article
System: The UNT Digital Library

Wind Turbine Manufacturers in the United States: Locations and Local Impacts

Suzanne Tegen's presentation about U.S. wind energy manufacturing (presented at WINDPOWER 2010 in Dallas) provides information about challenges to modeling renewables; wind energy's economic "ripple effect"; case studies about wind-related manufacturing in Colorado, Iowa, Ohio, and Indiana; manufacturing maps for the Great Lakes region, Arkansas, and the United States; sample job announcements; and U.S. Treasury Grant 1603 funding.
Date: May 26, 2010
Creator: Tegen, S.
Object Type: Presentation
System: The UNT Digital Library
Commissioning of the LHC Low Level RF System Remote Configuration Tools (open access)

Commissioning of the LHC Low Level RF System Remote Configuration Tools

The LHC Low Level RF system (LLRF) is a complex multi-loop system used to regulate the superconductive cavity gap voltage as well as to reduce the impedance presented by RF stations to the beam. The RF system can have a profound impact on the stability of the beam; a mis-configured RF system has the potential of causing longitudinal instabilities, beam diffusion and beam loss. To configure the RF station for operation, a set of parameters in the LLRF multi-loop system have to be defined. Initial system commissioning as well as ongoing operation requires a consistent method of computer based remote measurement and model-based design of each RF station feedback system. This paper describes the suite of Matlab tools used for configuring the LHC RF system during the start up in Nov2009-Feb2010. We present a brief overview of the tool, examples of commissioning results, and basics of the model-based design algorithms. This work complements our previous presentation, where the algorithms and methodology followed in the tools were described.
Date: August 26, 2010
Creator: Van Winkle, Daniel; Fox, John; Mastorides, Themis; Rivetta, Claudio; Baudrenghien, Philippe; Butterworth, Andrew et al.
Object Type: Article
System: The UNT Digital Library
The Suitability of Sodium Peroxide Fusion for Production-Scale Plutonium Processing Operations (open access)

The Suitability of Sodium Peroxide Fusion for Production-Scale Plutonium Processing Operations

Sodium peroxide (Na{sub 2}O{sub 2}) fusion is a method that offers significant benefits to the processing of high-fired plutonium oxide (PuO{sub 2}) materials. Those benefits include reduction in dissolution cycle time, decrease in residual solids, and reduction of the potential for generation of a flammable gas mixture during dissolution. Implementation of Na{sub 2}O{sub 2} fusion may also increase the PuO{sub 2} throughput in the HB-Line dissolving lines. To fuse a material, Na{sub 2}O{sub 2} is mixed with the feed material in a crucible and heated to 600-700 C. For low-fired and high-fired PuO{sub 2}, Na{sub 2}O{sub 2} reacts with PuO{sub 2} to form a compound that readily dissolves in ambient-temperature nitric acid without the use of potassium fluoride. The Savannah River National Laboratory (SRNL) demonstrated the feasibility of Na{sub 2}O{sub 2} fusion and subsequent dissolution for the processing of high-fired PuO{sub 2} materials in HB-Line. Testing evaluated critical dissolution characteristics and defined preliminary process parameters. Based on experimental measurements, a dissolution cycle can be complete in less than one hour, compared to the current processing time of 6-10 hours for solution heating and dissolution. Final Pu concentrations of 30-35 g/L were produced without the formation of precipitates in the final …
Date: October 26, 2010
Creator: Pierce, R. & Edwards, T.
Object Type: Article
System: The UNT Digital Library
Radiation Protection Aspects of the Linac Coherent Light Source Front End Enclosure (open access)

Radiation Protection Aspects of the Linac Coherent Light Source Front End Enclosure

The Front End Enclosure (FEE) of the Linac Coherent Light Source (LCLS) is a shielding housing located between the electron dump area and the first experimental hutch. The upstream part of the FEE hosts the commissioning diagnostics for the FEL beam. In the downstream part of the FEE, two sets of grazing incidence mirror and several collimators are used to direct the beam to one of the experimental stations and reduce the bremsstrahlung background and the hard component of the spontaneous radiation spectrum. This paper addresses the beam loss assumptions and radiation sources entering the FEE used for the design of the FEE shielding using the Monte-Carlo code FLUKA. The beam containment system prevents abnormal levels of radiations inside the FEE and ensures that the beam remains in its intended path is also described.
Date: August 26, 2010
Creator: Vollaire, J.; Fasso, A.; Liu, J.C.; Mao, X.S.; Prinz, A.; Rokni, S.H. et al.
Object Type: Article
System: The UNT Digital Library
Atmospheric Radiation Measurement Program Climate Research Facility Operation Quarterly Report July 1 - September 30, 2010. (open access)

Atmospheric Radiation Measurement Program Climate Research Facility Operation Quarterly Report July 1 - September 30, 2010.

Individual raw datastreams from instrumentation at the Atmospheric Radiation Measurement (ARM) Climate Research Facility fixed and mobile sites are collected and sent to the Data Management Facility (DMF) at Pacific Northwest National Laboratory (PNNL) for processing in near real-time. Raw and processed data are then sent approximately daily to the ARM Archive, where they are made available to users. For each instrument, we calculate the ratio of the actual number of data records received daily at the Archive to the expected number of data records. The results are tabulated by (1) individual datastream, site, and month for the current year and (2) site and fiscal year (FY) dating back to 1998. The U.S. Department of Energy (DOE) requires national user facilities to report time-based operating data. The requirements concern the actual hours of operation (ACTUAL); the estimated maximum operation or uptime goal (OPSMAX), which accounts for planned downtime; and the VARIANCE [1-(ACTUAL/OPSMAX)], which accounts for unplanned downtime. The OPSMAX time for the fourth quarter of FY2010 for the Southern Great Plains (SGP) site is 2097.60 hours (0.95 2208 hours this quarter). The OPSMAX for the North Slope of Alaska (NSA) locale is 1987.20 hours (0.90 2208) and for the Tropical …
Date: October 26, 2010
Creator: Sisterson, D. L.
Object Type: Report
System: The UNT Digital Library
Status Update on the Second-Generation ILC Marx Modulator Prototype (open access)

Status Update on the Second-Generation ILC Marx Modulator Prototype

This paper is a status update of the SLAC P2 Marx. This Marx-topology klystron modulator is a second-generation modulator which builds upon experience gained from the SLAC P1 Marx. There are several fundamental differences between these modulators including the correction scheme, bus voltages, and the control system architecture. These differences, along with preliminary experimental results and the schedule for further development, are detailed in this paper.
Date: August 26, 2010
Creator: Kemp, Mark A.; Benwell, Andrew; Burkhart, Craig; Larsen, Ray; MacNair, David; Nguyen, Minh et al.
Object Type: Article
System: The UNT Digital Library
Cold Nuclear Matter Effects on J/psi Production: Intrinsic and Extrinsic Transverse Momentum Effects (open access)

Cold Nuclear Matter Effects on J/psi Production: Intrinsic and Extrinsic Transverse Momentum Effects

Cold nuclear matter effects on J/{psi} production in proton-nucleus and nucleus-nucleus collisions are evaluated taking into account the specific J/{psi}-production kinematics at the partonic level, the shadowing of the initial parton distributions and the absorption in the nuclear matter. We consider two different parton processes for the c{bar c}-pair production: one with collinear gluons and a recoiling gluon in the final state and the other with initial gluons carrying intrinsic transverse momentum. Our results are compared to RHIC observables. The smaller values of the nuclear modification factor R{sub AA} in the forward rapidity region (with respect to the mid rapidity region) are partially explained, therefore potentially reducing the need for recombination effects.
Date: August 26, 2010
Creator: Ferreiro, E.G.; U., /Santiago de Compostela; Fleuret, F.; Polytechnique, /Ecole; Lansberg, J.P.; U., /Heidelberg et al.
Object Type: Article
System: The UNT Digital Library