Coalescence of minijet partons with partons from the quark-gluon plasma formed in relativistic heavy ion collisions is suggested as the mechanism for production of hadrons with intermediate ...transverse momentum. The resulting enhanced antiproton and pion yields at intermediate transverse momenta give a plausible explanation for the observed large antiproton to pion ratio. With further increasing momentum, the ratio is predicted to decrease and approach the small value given by independent fragmentations of minijet partons after their energy loss in the quark-gluon plasma.
Results of resonance searches in the Xi(-)pi(-), Xi(-)pi(+), Xi;(+)pi(-), and Xi;(+)pi(+) invariant mass spectra in proton-proton collisions at sqrts=17.2 GeV are presented. Evidence is shown for the ...existence of a narrow Xi(-)pi(-) baryon resonance with mass of 1.862+/-0.002 GeV/c(2) and width below the detector resolution of about 0.018 GeV/c(2). The significance is estimated to be above 4.2sigma. This state is a candidate for the hypothetical exotic Xi(--)(3/2) baryon with S=-2, I=3 / 2, and a quark content of (dsdsū). At the same mass, a peak is observed in the Xi(-)pi(+) spectrum which is a candidate for the Xi(0)(3/2) member of this isospin quartet with a quark content of (dsus-d). The corresponding antibaryon spectra also show enhancements at the same invariant mass.
Vladimir Naumovich Gribov was one of the most outstanding theorists, a key figure in the creation of the modern elementary particle physics. His many discoveries are famous and well accepted by the ...physics community (Gribov-Regge theory of high energy hadron interactions, Gribov vacuum pole — Pomeron, Reggeon field theory, parton evolution equations, neutrino oscillations, Gribov copies in non-Abelian gauge field theories, etc.); Some of his ideas look unacceptable and strange at the first glance. Even at the second glance. Nowadays, under the weight of new theoretical developments and experimental results, his ideas are receiving the recognition they deserve. The Gribov Memorial Workshop, organized on his 75th birthday in Budapest, Hungary in 2005, clearly demonstrated the wealth and fertilization force of his ideas. Close colleagues, younger followers, world experts of the quark-hadron world have gathered together to display new angles of the Gribov heritage. And to remember the personality of a great man. This book collects the talks presented at, and contributed to, the Gribov-75 Memorial Workshop.
The site characterisation of future underground gravitational wave detectors is based on spectral properties of the low frequency seismic noise. The evaluation of the collected long term ...seismological data in the Mátra Gravitational and Geophysical Laboratory revealed some aspects that are not apparent in short term spectral noise characterisation. In this paper we survey the methodology. In particular, we argue that the spectral properties are best represented by percentiles of the data instead of the mode, because it is noisy, sensitive to the discretization and intrinsic averaging, therefore it is less suitable for a robust characterisation. The suitable cumulative measures are also scrutinized.
Real-time interferometric diagnostics of rubidium plasma Djotyan, G.P.; Bakos, J.S.; Kedves, M.Á. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2018, Letnik:
884
Journal Article
Recenzirano
A method of interferometric real-time diagnostics is developed and applied to rubidium plasma created by strong laser pulses in the femtosecond duration range at different initial rubidium vapor ...densities using a Michelson-type interferometer. A cosine fit with an exponentially decaying relative phase is applied to the obtained time-dependent interferometry signals to measure the density–length product of the created plasma and its recombination time constant. The presented technique may be applicable for real-time measurements of rubidium plasma dynamics in the AWAKE experiment at CERN, as well as for real-time diagnostics of plasmas created in different gaseous media and on surfaces of solid targets.
Heavy quark jet quenching in high energy nuclear collisions became a decisive tool to distinguish between theories based on Standard Model perturbative QCD and AdS/CFT gravity dual models. The ...momentum independence and inverse quark mass dependence of the drag coefficient in AdS/CFT differs substantially from the characteristic
log
(
p
T
/
M
)
/
p
T
variation of the heavy quark drag in QCD, which was obtained from early calculations. The latest pQCD efforts on heavy quark energy loss include color magnetic dynamical effects and final size non-static coherence effects in perturbative quark gluon plasmas and the obtained results are much closer to the experimental data for heavy quarks. We discuss our recent understanding of heavy quark quenching and summarize the measurable quantities to distinguish between the pQCD and AdS/CFT scenarios.
We introduce a quasi-particle model of strongly interacting quark-gluon matter and explore the possible connection to an effective field theoretical description consisting of a scalar
σ field by ...introducing a dynamically generated mass,
M
(
σ
)
, and a self-consistently determined interaction term,
B
(
σ
)
. We display a possible connection between the two types of effective description, using the Friedberg-Lee model.
A systematic expansion in opacity, L/lambda, is used to clarify the nonlinear behavior of induced gluon radiation in quark-gluon plasmas. The inclusive differential gluon distribution is calculated ...up to second order in opacity and compared to the zeroth order (factorization) limit. The opacity expansion makes it possible to take finite kinematic constraints into account that suppress jet quenching in nuclear collisions below RHIC (square root of s = 200 AGeV) energies.
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