806 research outputs found
Unparticle contribution to the hydrogen atom ground state energy
In the present work we study the effect of unparticle modified static
potentials on the energy levels of the hydrogen atom. By using
Rayleigh-Schr\"odinger perturbation theory, we obtain the energy shift of the
ground state and we compare it with experimental data. Bounds on the unparticle
energy scale as a function of the scaling dimension
and the coupling constant are derived. We show that
there exists a parameter region where bounds on are
stringent, signalling that unparticles could be tested in atomic physics
experiments.Comment: 11 pages, 3 figure
Hadronization conditions in relativistic nuclear collisions and the QCD pseudo-critical line
We compare the reconstructed hadronization conditions in relativistic nuclear
collisions in the nucleon-nucleon centre-of-mass energy range 4.7-2760 GeV in
terms of temperature and baryon-chemical potential with lattice QCD
calculations, by using hadronic multiplicities. We obtain hadronization
temperatures and baryon chemical potentials with a fit to measured
multiplicities by correcting for the effect of post-hadronization rescattering.
The post-hadronization modification factors are calculated by means of a
coupled hydrodynamical-transport model simulation under the same conditions of
approximate isothermal and isochemical decoupling as assumed in the statistical
hadronization model fits to the data. The fit quality is considerably better
than without rescattering corrections, as already found in previous work. The
curvature of the obtained "true" hadronization pseudo-critical line kappa is
found to be 0.0048 +- 0.0026, in agreement with lattice QCD estimates; the
pseudo-critical temperature at vanishing mu_B is found to be 164.3+-1.8 MeV.Comment: 9 pages, 2 figures. Minor corrections, version published in PL
Centrality and Energy Dependence of Proton, Light Fragment and Hyperon Production
Recent results of the NA49 collaboration are discussed. These include the
energy dependence of stopping and the production of the light fragments t and
3He. New data on the system size dependence of hyperon production at 40A and
158AGeV are also presented.Comment: 4 pages, Quark Matter 2006 proceeding
Resonance Production in RHIC Collisions
Results of resonance particle production measured at RHIC in 200 GeV Au+Au collisions are compared to measurements in p+p and d+Au
collisions in order to verify the existence of an extended hardronically
interacting medium. Yield and momentum distributions of resonances maybe
modified during the fireball lifetime due to resonance decay and the subsequent
rescattering of their decay daughters as well as the regeneration of resonances
from their decay products. Modified momentum spectra in heavy ion collisions
may change the nuclear modification factor R. The influence on the
elliptic flow v due to late regeneration of resonances is discussed.Comment: 6 pages, 6 figures, Proceedings of the 22st Winter Workshop on
Nuclear Dynamics, San Diago, California, 12-18 March, 200
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Zugzwangs in chess studies
Van der Heijden’s ENDGAME STUDY DATABASE IV, HHDBIV, is the definitive collection of 76,132 chess studies. The zugzwang position or zug, one in which the side to move would prefer not to, is a frequent theme in the literature of chess studies. In this third data-mining of HHDBIV, we report on the occurrence of sub-7-man zugs there as discovered by the use of CQL and Nalimov endgame tables (EGTs). We also mine those Zugzwang Studies in which a zug more significantly appears in both its White-to-move (wtm) and Black-to-move (btm) forms. We provide some illustrative and extreme examples of zugzwangs in studies
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Uniqueness in chess studies
Van der Heijden’s ENDGAME STUDY DATABASE IV, HhdbIV, is the definitive collection of 76,132 chess studies. In each one, White is to achieve the stipulated goal, win or draw: study solutions should be essentially unique with minor alternatives at most. In this second note on the mining of the database, we use the definitive Nalimov endgame tables to benchmark White’s moves in sub-7-man chess against this standard of uniqueness. Amongst goal-compatible mainline positions and goal-achieving moves, we identify the occurrence of absolutely unique moves and analyse the frequency and lengths of absolutely-unique-move sequences, AUMSs. We identify the occurrence of equi-optimal moves and suboptimal moves and refer to a defined method for classifying their significance
Hadronic Freeze-Out in A+A Collisions meets the Lattice QCD Parton-Hadron Transition Line
We analyze hadrochemical freeze-out in central Pb+Pb collisions at CERN SPS
and LHC energies. Employing the UrQMD hybrid transport model we study the
effects of the final hadron/resonance expansion phase on the hadron
multiplicities established at hadronization. The bulk meson yields freeze out
directly at hadronization whereas the baryon-antibaryon sector is subject to
significant alterations, due to annihilation and regeneration processes. We
quantify the latter changes by survival factors for each species which are
applied to modify the statistical model predictions for the data. The modified
SM analysis recovers the hadronization points, which coincide with the recent
lattice QCD predictions of the parton-hadron transition line at finite
baryochemical potential.Comment: Proceedings of the 8th International Workshop on Critical Point and
Onset of Deconfinement, March 11 to 15, 2013 Napa, California, US
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