560 research outputs found
Recent HBT results in Au+Au and p+p collisions from PHENIX
We present Hanbury-Brown Twiss measurements from the PHENIX experiment at
RHIC for final results for charged kaon pairs from sqrt{s_{NN}} = 200 GeV Au+Au
collisions and preliminary results for charged pion pairs from sqrt{s} = 200
GeV p+p collisions. We find that for kaon pairs from Au+Au, each traditional 3D
Gaussian radius shows approximately the same linear increase as a function of
N^{1/3}_{part}. An imaging analysis reveals a significant non-Gaussian tail for
r \gtrsim 10 fm. The presence of a tail for kaon pairs demonstrates that
similar non-Gaussian tails observed in earlier pion measurements cannot be
fully explained by decays of long-lived resonances. The preliminary analysis of
pions from sqrt{s} = 200 GeV p+p minimum biased collisions show correlations
which are well suited to traditional 3D HBT radii extraction via the
Bowler-Sinyukov method, and we present R_out, R_side, and R_long as a function
of mean transverse pair mass.Comment: 4 pages, 3 figures - To appear in the conference proceedings for
Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse
Towards a class compromise in South Africa's "double transition": bargained liberalization and the consolidation of democracy
Paper presented at the Wits History Workshop: Forging the links between historical research and the policy process, 18-19 September 1999.South Africa's 1994 settlement ensured the survival of one of the world's most unequal capitalist systems. Liberals liked that it was based on the international economic order. All that changed was the inclusion of a few Blacks in the economic power of the White corporate elite. Change came though a conservative pact. What is needed is a class compromise which allows for engaging in the global economy but limits economic liberalisation, i.e. bargained (limited) liberalization not complete economic liberalization
Femtoscopic results in Au+Au and p+p from PHENIX at RHIC
Ultra-relativistic gold-gold and proton-proton collisions are investigated in
the experiments of the Relativistic Heavy Ion Collider (RHIC). In the last
several years large amount of results were revealed about the matter created in
these collisions. The latest PHENIX results for femtoscopy and correlations are
reviewed in this paper. Bose-Einstein correlations of charged kaons in 200 GeV
Au+Au collisions and of charged pions in 200 GeV p+p collisions are shown. They
are both compatible with previous measurements of charged pions in gold-gold
collisions, with respect to transverse mass or number of participants scaling.Comment: Talk given at the VI Workshop on Particle Correlations and
Femtoscopy, Kiev, September 14-18, 2010. 6 pages, 4 figures. This work was
supported by the OTKA grant NK73143 and M. Csanad's Bolyai scholarshi
Constraining models with vector-like fermions from FCNC in K and B physics
In this work, we update the constraints on tree level FCNC couplings in the
framework of a theory with n isosinglet vector-like down quarks. In this
context, we emphasize the sensitivity of the B -> J/psi K_S CP asymmetry to the
presence of new vector-like down quarks. This CP asymmetry, together with the
rare decays B -> X_{s,d} l bar{l} and K -> pi nu bar{nu} are the best options
to further constrain the FCNC tree level couplings or even to point out, in the
near future, the possible presence of vector-like quarks in the low energy
spectrum, as suggested by GUT theories or models of large extra dimensions at
the TeV scale.Comment: 29 pages 11 figures. Comments on the calculation of epsilon' added,
references included, conclusions unchange
Neutrino Zero Modes on Electroweak Strings
Zero modes of massive standard model fermions have been found on electroweak
Z-strings. A zero mode solution for a massless left-handed neutrino is also
known, but was thought to be non-normalizable. Here we show that although this
mode is not discretely normalizable, it is delta-function normalizable and the
correct interpretation of this solution is within the framework of the
continuum spectrum. We also analyze an extension of the standard model
including right-handed neutrinos in which neutrinos have Dirac masses, arising
from a Yukawa coupling to the usual SU(2) Higgs doublet, and right-handed
Majorana masses. The Majorana mass terms are taken to be spatially homogeneous
and are presumed to arise from the vacuum expectation value of some field
acquired in a phase transition well above the electroweak phase transition. The
resulting zero energy equations have a discrete zero mode.Comment: 5 pages, 1 figures, version to appear in Phys. Rev.
Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration
Extensive experimental data from high-energy nucleus-nucleus collisions were
recorded using the PHENIX detector at the Relativistic Heavy Ion Collider
(RHIC). The comprehensive set of measurements from the first three years of
RHIC operation includes charged particle multiplicities, transverse energy,
yield ratios and spectra of identified hadrons in a wide range of transverse
momenta (p_T), elliptic flow, two-particle correlations, non-statistical
fluctuations, and suppression of particle production at high p_T. The results
are examined with an emphasis on implications for the formation of a new state
of dense matter. We find that the state of matter created at RHIC cannot be
described in terms of ordinary color neutral hadrons.Comment: 510 authors, 127 pages text, 56 figures, 1 tables, LaTeX. Submitted
to Nuclear Physics A as a regular article; v3 has minor changes in response
to referee comments. Plain text data tables for the points plotted in figures
for this and previous PHENIX publications are (or will be) publicly available
at http://www.phenix.bnl.gov/papers.htm
Phenomenology of non-standard Z couplings in exclusive semileptonic b -> s transitions
The rare decays , and
are analyzed in a generic scenario where New Physics effects
enter predominantly via penguin contributions. We show that this
possibility is well motivated on theoretical grounds, as the vertex
is particularly susceptible to non-standard dynamics. In addition, such a
framework is also interesting phenomenologically since the coupling
is rather poorly constrained by present data. The characteristic features of
this scenario for the relevant decay rates and distributions are investigated.
We emphasize that both sign and magnitude of the forward-backward asymmetry of
the decay leptons in , , carry sensitive information on New Physics. The observable is proposed as a useful probe of
non-standard CP violation in couplings.Comment: Minor modifications; version to appear in Phys. Rev.
Harnessing the NEON data revolution to advance open environmental science with a diverse and data-capable community
It is a critical time to reflect on the National Ecological Observatory Network (NEON) science to date as well as envision what research can be done right now with NEON (and other) data and what training is needed to enable a diverse user community. NEON became fully operational in May 2019 and has pivoted from planning and construction to operation and maintenance. In this overview, the history of and foundational thinking around NEON are discussed. A framework of open science is described with a discussion of how NEON can be situated as part of a larger data constellation—across existing networks and different suites of ecological measurements and sensors. Next, a synthesis of early NEON science, based on \u3e100 existing publications, funded proposal efforts, and emergent science at the very first NEON Science Summit (hosted by Earth Lab at the University of Colorado Boulder in October 2019) is provided. Key questions that the ecology community will address with NEON data in the next 10 yr are outlined, from understanding drivers of biodiversity across spatial and temporal scales to defining complex feedback mechanisms in human–environmental systems. Last, the essential elements needed to engage and support a diverse and inclusive NEON user community are highlighted: training resources and tools that are openly available, funding for broad community engagement initiatives, and a mechanism to share and advertise those opportunities. NEON users require both the skills to work with NEON data and the ecological or environmental science domain knowledge to understand and interpret them. This paper synthesizes early directions in the community’s use of NEON data, and opportunities for the next 10 yr of NEON operations in emergent science themes, open science best practices, education and training, and community building
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