54 Matching Results

Search Results

Advanced search parameters have been applied.

Scientific Presentation. 7th Meeting of the Management Steering Committee of the RIKEN BNL Collaboration.

Description: The RIKEN BNL Research Center (RBRC) was established in April 1997 at Brookhaven National Laboratory. It is funded by the ''Rikagaku Kenkysho,'' (RIKEN) The Institute of Physical and Chemical Research, of Japan. The Center is dedicated to the study of strong 'interactions, including hard QCD/spin physics, lattice QCD and RHIC (Relativistic Heavy Ion Collider) physics through nurturing of a new generation of young physicists. The Director of RBRC is Professor T. D. Lee. The first years were dedicated to the establishment of a theory group. This has essentially been completed consisting of Fellows, Postdocs, and RHIC Physics/University Fellows, with an active group of consultants. The center also organizes an extensive series of workshops on specific topics in strong interactions with an accompanying series of published proceedings. In addition, a 0.6 teraflop parallel processor computer has been constructed and operational since August 1998. It was awarded the Supercomputer 1998 Gordon Bell Prize for price performance. An active experimental group centered around the spin physics program at RHIC has subsequently also been established at RBRC. It presently consists of five Fellows, one Postdoc and several scientific collaborators with more appointments being expected in the near future. Members and participants of RBRC on occasion will develop articles such as this one, in the nature of a status report or a general review.
Date: February 13, 2001
Creator: Lee,T. D.
Partner: UNT Libraries Government Documents Department

Scientific Presentation. 7th Meeting of the Management Steering Committee of the RIKEN BNL Collaboration.

Description: The RIKEN BNL Research Center (RBRC) was established in April 1997 at Brookhaven National Laboratory. It is funded by the ''Rikagaku Kenkysho,'' (RIKEN) The Institute of Physical and Chemical Research, of Japan. The Center is dedicated to the study of strong interactions, including hard QCD/spin physics, lattice QCD and RHIC (Relativistic Heavy Ion Collider) physics through nurturing of a new generation of young physicists. The Director of RBRC is Professor T. D. Lee. The first years were dedicated to the establishment of a theory group. This has essentially been completed consisting of Fellows, Postdocs, and RHIC Physics/University Fellows, with an active group of consultants. The center also organizes an extensive series of workshops on specific topics in strong interactions with an accompanying series of published proceedings. In addition, a 0.6 teraflop parallel processor computer has been constructed and operational since August 1998. It was awarded the Supercomputer 1998 Gordon Bell Prize for price performance. An active experimental group centered around the spin physics program at RHIC has subsequently also been established at RBRC. It presently consists of five Fellows, one Postdoc and several scientific collaborators with more appointments being expected in the near future. Members and participants of RBRC on occasion will develop articles such as this one, in the nature of a status report or a general review.
Date: February 13, 2001
Creator: Lee, T. D.
Partner: UNT Libraries Government Documents Department

QUARKONIUM PRODUCTION IN RELATIVISTIC NUCLEAR COLLISIONS. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP, VOLUME 12

Description: The RIKEN-BNL Workshop on Quarkonium Production in Relativistic Nuclear Collisions was held September 28--October 2, 1998, at Brookhaven National Laboratory. The Workshop brought together about 50 invited participants from around the world and a number of Brookhaven physicists from both particle and nuclear physics communities.
Date: April 20, 1999
Creator: Kharzeev, D.
Partner: UNT Libraries Government Documents Department

Summary (Summary Talk at the Quarkonium Production in Nuclear Collisions Workshop).

Description: This summary is an attempt to overview the wealth of new results and ideas in quarkonium physics presented at the Seattle Workshop. The Workshop in Seattle has shown that the physics of heavy quarkonium continues to develop at a fast pace; moreover, we have every reason to believe that the next year, with RHIC turning on, will mark the beginning of the new exciting era in this field.
Date: May 11, 1998
Creator: Kharzeev, D.
Partner: UNT Libraries Government Documents Department

The Parity Partner of the Nucleon in Quenched QCD With Domain Wall Fermions

Description: The authors present preliminary results for the mass spectrum of the nucleon and its low-lying excited states from quenched lattice QCD using the domain wall fermion method which preserves the chiral symmetry at finite lattice cutoff. Definite mass splitting is observed between the nucleon and its parity partner. This splitting grows with decreasing valence quark mass. They also present preliminary data regarding the first positive-parity excited state.
Date: July 12, 2000
Creator: Sasaki, S.
Partner: UNT Libraries Government Documents Department

Strange Dibaryons in Neutron Stars and in Heavy-Ion Collisons.

Description: The formation of dibaryons with strangeness are discussed for the interior of neutron stars and for central relativistic heavy-ion collisions. We derive limits for the properties of H-dibaryons from pulsar data. Signals for the formation of possible bound states with hyperons at BNL's Relativistic Heavy-Ion Collider (RHIC) are investigated by studying their weak decay patterns and production rates.
Date: April 25, 2001
Creator: Schaffner-Bielich, J.
Partner: UNT Libraries Government Documents Department

RIKEN BNL RESEARCH CENTER WORKSHOP ON HIGH ENERGY POLARIMETRY, VOLUME 23

Description: The RHIC collider, in its pp mode, will be a unique machine. It will open up a new frontier in the use of spin in the study of hadronic physics. Using its polarized beams, a whole new range of tests of the Standard Model will become feasible, and much new information about the detailed partonic structure of-the nucleon will emerge. It will also be possible to answer intriguing questions concerning the relationship between pp and pp total cross-sections and real parts of forward amplitudes, questions which are relevant to attempts to understand certain aspects of non-perturbative QCD. This entire, rich program relies upon an accurate determination of the polarization of the proton beams, a matter which is far from trivial. In the summer of 1997 Larry Trueman and the author ran a six-week Working Group, the aim of which was to try to understand theoretically the accuracy with which one could predict the analyzing power of various reactions which were under consideration as high energy proton polarimeters. The results of the study were somewhat negative in the sense that they concluded that analyzing powers could only be predicted to within an accuracy of {+-}10%, whereas RHIC was aiming for {+-}5%. On the other hand some very positive consequences followed. The working group stimulated the study of a polarimeter based on CNI in proton-carbon scattering and this is the polarimeter that will be used in the early stages of RHIC operation. It will be regarded as a relative polarimeter and will have to be calibrated absolutely at some later stage, probably via use of a polarized jet hydrogen target. In addition the surprising discovery was made that proton-proton elastic scattering, at high energy and very small momentum transfer, is self-spin analyzing, in the sense that the measurement of a sufficient number ...
Date: June 15, 2000
Creator: Leader, E.
Partner: UNT Libraries Government Documents Department

QCD Phase Transitions-Volume 15.

Description: The title of the workshop, ''The QCD Phase Transitions'', in fact happened to be too narrow for its real contents. It would be more accurate to say that it was devoted to different phases of QCD and QCD-related gauge theories, with strong emphasis on discussion of the underlying non-perturbative mechanisms which manifest themselves as all those phases. Before we go to specifics, let us emphasize one important aspect of the present status of non-perturbative Quantum Field Theory in general. It remains true that its studies do not get attention proportional to the intellectual challenge they deserve, and that the theorists working on it remain very fragmented. The efforts to create Theory of Everything including Quantum Gravity have attracted the lion share of attention and young talent. Nevertheless, in the last few years there was also a tremendous progress and even some shift of attention toward emphasis on the unity of non-perturbative phenomena. For example, we have seen some. efforts to connect the lessons from recent progress in Supersymmetric theories with that in QCD, as derived from phenomenology and lattice. Another example is Maldacena conjecture and related development, which connect three things together, string theory, super-gravity and the (N=4) supersymmetric gauge theory. Although the progress mentioned is remarkable by itself, if we would listen to each other more we may have chance to strengthen the field and reach better understanding of the spectacular non-perturbative physics.
Date: November 4, 1998
Creator: Schafer, T.
Partner: UNT Libraries Government Documents Department

Strange Goings on in Quark Matter.

Description: We review recent work on how the superfluid state of three flavor quark matter is affected by non-zero quark masses and chemical potentials. The study of hadronic matter at high baryon density has recently attracted a lot of interest. At zero baryon density chiral symmetry is broken by a quark-anti-quark condensate. At high density condensation in the quark-anti-quark channel is suppressed. Instead, attractive interactions in the color anti-symmetric quark-quark channel favor the formation of diquark condensates. As a consequence, cold dense quark matter is expected to be a color superconductor. The symmetry breaking pattern depends on the density, the number of quark flavors, and their masses. A particularly symmetric phase is the color-flavor-locked (CFL) phase of three flavor quark matter. This phase is believed to be the true ground state of ordinary matter at very large density.
Date: June 5, 2001
Creator: Schafer, T.
Partner: UNT Libraries Government Documents Department

PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP, RHIC SPIN COLLABORATION MEETINGS XII AND XIII, SEPTEMBER 16, 2002, OCTOBER 22, 2002.

Description: Since its inception, the RHIC Spin Collaboration (RSC) has held semi-regular meetings each year to discuss the physics possibilities and the operational details of the program. Having collected our first data sample of polarized proton-proton collisions in Run02 of RHIC, we are now in the process of examining the performance of both the accelerator and the experiments. During the PAC meeting on August 29, 2002, the beam use proposal with a four week, polarized proton physics run was approved as part of the plan for Run-03. So, we meet at BNL on September 16, 2002 to discuss the concrete plans for this proton-proton run.
Date: March 6, 2003
Creator: Fox, B.
Partner: UNT Libraries Government Documents Department

NUMERICAL ALGORITHMS AT NON-ZERO CHEMICAL POTENTIAL. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP, VOLUME 19

Description: The RIKEN BNL Research Center hosted its 19th workshop April 27th through May 1, 1999. The topic was Numerical Algorithms at Non-Zero Chemical Potential. QCD at a non-zero chemical potential (non-zero density) poses a long-standing unsolved challenge for lattice gauge theory. Indeed, it is the primary unresolved issue in the fundamental formulation of lattice gauge theory. The chemical potential renders conventional lattice actions complex, practically excluding the usual Monte Carlo techniques which rely on a positive definite measure for the partition function. This ''sign'' problem appears in a wide range of physical systems, ranging from strongly coupled electronic systems to QCD. The lack of a viable numerical technique at non-zero density is particularly acute since new exotic ''color superconducting'' phases of quark matter have recently been predicted in model calculations. A first principles confirmation of the phase diagram is desirable since experimental verification is not expected soon. At the workshop several proposals for new algorithms were made: cluster algorithms, direct simulation of Grassman variables, and a bosonization of the fermion determinant. All generated considerable discussion and seem worthy of continued investigation. Several interesting results using conventional algorithms were also presented: condensates in four fermion models, SU(2) gauge theory in fundamental and adjoint representations, and lessons learned from strong; coupling, non-zero temperature and heavy quarks applied to non-zero density simulations.
Date: September 14, 1999
Creator: BLUM,T.
Partner: UNT Libraries Government Documents Department

PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ON RHIC SPIN PHYSICS III AND IV, POLARIZED PARTONS AT HIGH Q2 REGION, AUGUST 3, 2000 AT BNL, OCTOBER 14, 2000 AT KYOTO UNIVERSITY.

Description: International workshop on II Polarized Partons at High Q2 region 11 was held at the Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, Japan on October 13-14, 2000, as a satellite of the international conference ''SPIN 2000'' (Osaka, Japan, October 16-21,2000). This workshop was supported by RIKEN (The Institute of Physical and Chemical Research) and by Yukawa Institute. The scientific program was focused on the upcoming polarized collider RHIC. The workshop was also an annual meeting of RHIC Spin Collaboration (RSC). The number of participants was 55, including 28 foreign visitors and 8 foreign-resident Japanese participants, reflecting the international nature of the RHIC spin program. At the workshop there were 25 oral presentations in four sessions, (1) RHIC Spin Commissioning, (2) Polarized Partons, Present and Future, (3) New Ideas on Polarization Phenomena, (4) Strategy for the Coming Spin Running. In (1) the successful polarized proton commissioning and the readiness of the accelerator for the physics program impressed us. In (2) and (3) active discussions were made on the new structure function to be firstly measured at RHIC, and several new theoretical ideas were presented. In session (4) we have established a plan for the beam time requirement toward the first collision of polarized protons. These proceedings include the transparencies presented at the workshop. The discussion on ''Strategy for the Coming Spin Running'' was summarized by the chairman of the session, S. Vigdor and G. Bunce.
Date: March 15, 2001
Creator: Bunce, G. & Vigdor, S.
Partner: UNT Libraries Government Documents Department

Prompt Photon Production in Polarized Hadron Collisions.

Description: We consider spin asymmetries for prompt photon production in collisions of longitudinally polarized hadrons. This reaction will be a key tool at the BNL-RHIC {rvec p}{rvec p} collider for determining the gluon spin density in a polarized proton. We study the effects of QCD corrections, such as all-order soft-gluon ''threshold'' resummations.
Date: April 25, 2000
Creator: Vogelsang, W.
Partner: UNT Libraries Government Documents Department

Domain wall fermion calculation of nucleon G{sub A}/G{sub V}

Description: The authors present a preliminary domain-wall fermion lattice-QCD calculation of isovector vector and axial charges, g{sub V} and g{sub A}, of the nucleon. Since the lattice renormalizations, Z{sub V} and Z{sub A}, of the currents are identical with DWF, the lattice ratio (g{sub A}/g{sub V}){sup lattice} directly yields the continuum value. Indeed Z{sub V} determined from the matrix element of the vector current agrees closely with Z{sub A} from a non-perturbative renormalization study of quark bilinears. They also obtain spin related quantities {Delta}q/g{sub V} and {delta}q/g{sub V}.
Date: August 17, 2000
Creator: Blum, T.; Ohta, S. & Sasaki, S.
Partner: UNT Libraries Government Documents Department

Proceedings of RIKEN/BNL Research Center Workshop Future Transversity Measurements (Volume 29).

Description: The RIKEN-BNL Research Center workshop on ''Future Transversity Measurements'' was held at BNL from September 18-20, 2000. The main goal of the workshop was to explore future measurements of transversity distributions. This issue is of importance to the RHIC experiments, which will study polarized proton-proton collisions with great precision. One of the workshop's goals was to enhance interactions between the DIS community at HERA and the spin community at RHIC in this field. The workshop has been well received by the participants; the number of 69 registered participants demonstrates broad interest in the workshop's topics. The program contained 35 talks and there was ample time for lively discussions. The program covered all recent work in the field and in addition some very elucidating educational talks were given. At the workshop the present status of the field was discussed and it has succeeded in stimulating new experimental and theoretical studies (e.g. model calculations for interference fragmentation functions (IFF), IFF analysis at DELPHI). It also functioned to focus attention on the open questions that need to be resolved for near future experiments. In general, the conclusions were optimistic, i.e. measuring the transversity functions seems to be possible, although some new experimental hurdles will have to be taken.
Date: January 2, 2001
Creator: Boer, D. & Grosse Perdekamp, M.
Partner: UNT Libraries Government Documents Department

J/{Psi} suppression as an evidence for quark gluon matter

Description: The J/{psi} suppression was originally proposed as a signature of the quark-gluon plasma. Strong suppression of J/{psi} production was indeed observed recently by the NA50 Collaboration at CERN SPS. Is it the first signature of a long-awaited quark-gluon matter, or just a peculiar combination of ''conventional'' effects acting together to produce the puzzling pattern observed experimentally? In this lecture, I am trying to summarize the existing theoretical explanations.
Date: August 10, 1998
Creator: Kharzeev, D.
Partner: UNT Libraries Government Documents Department

Why Color-Flavor Locking Is Just Like Chiral Symmetry Breaking

Description: The authors review how a classification into representations of color and flavor can be used to understand the possible patterns of symmetry breaking for color superconductivity in dense quark matter. In particular, the authors show how for three flavors, color-flavor locking is precisely analogous to the usual pattern of chiral symmetry breaking in the QCD vacuum.
Date: May 10, 2000
Creator: Pisarski, R. D. & Rischke, D. H.
Partner: UNT Libraries Government Documents Department