Resonances play a unique role in the study of ultra-relativistic heavy-ion collisions. Resonance yields, which may be modified by rescattering and regeneration after hadronization, can be used to ...study the properties of the hadronic phase of the collision. The transversemomentum spectra of the proton and the ϕ(1020) can be used to study the mechanisms of particle production. In addition, resonance measurements in pp and p–Pb collisions help to distinguish initial-state effects from the effects of the hot and dense final state. The ALICE Collaboration has studied the K*(892)0 and ϕ(1020) mesons in pp, p–Pb, and Pb–Pb collisions. Measurements of many resonance properties, including pT spectra, integrated yields, masses, widths, mean pT values, and the nuclear modification factors RAA and RpPb, are presented and compared to measurements from other experiments, non-resonances, and the predictions of theoretical models.
The aim of this paper is to understand resonance production (and more generally particle production) for different collision systems, namely proton-proton (pp), proton-nucleus (pA), and ...nucleus-nucleus (AA) scattering at the LHC. We will investigate in particular particle yields and ratios versus multiplicity, using the same multiplicity definition for the three different systems, in order to analyse in a compact way the evolution of particle production with the system size and the origin of a very different system size dependence of the different particles.
In heavy-ion physics, measurements of short-lived hadronic resonances allow the properties of the hadronic phase of the collision to be studied. In addition, resonances can be used along with stable ...hadrons to study parton energy loss in the quark-gluon plasma and the mechanisms that shape hadron pT spectra at intermediate transverse momenta. Resonance measurements in small systems serve as a reference for heavy-ion collisions and contribute to searches for collective effects. An overview of recent results on hadronic resonance production measured in ALICE is presented. These results include the pT spectra and yields of the ρ(770)0, K*(892)0, and φ(1020) mesons in pp, p-Pb, and Pb-Pb collisions at different energies as well as the Σ(1385)± and Ξ (1530)0 baryons in pp and p-Pb collisions.
Hadronic resonances serve as unique probes in the study of the hot and dense nuclear matter produced in heavy-ion collisions. Properties of the hadronic phase of the collision can be extracted from ...measurements of the suppression of resonance yields. A comparison of the transverse-momentum spectra of the φ(1020) meson and the proton (which have similar masses) can be used to study particle production mechanisms. Resonance measurements in pp collisions provide input for tuning QCD-inspired particle production models and serve as reference measurements for other collision systems. Measurements of resonances in p-Pb collisions allow nuclear effects in the absence of a hot and dense final state to be studied. The ALICE Collaboration has measured resonances in pp, p-Pb, and Pb-Pb collisions. These measurements will be discussed and compared to results from other experiments and to theoretical models.
Properties of the hadronic phase of high-energy heavy-ion collisions can be studied by measuring the ratios of hadronic resonance yields to the yields of longer-lived particles. These ratios can be ...used to study the strength of re-scattering effects, the chemical freeze-out temperature, and the lifetime between chemical and kinetic freeze-out. The restoration of chiral symmetry during the early hadronic phase or near the phase transition may lead to shifts in the masses and increases in the widths of hadronic resonances. The ALICE collaboration has measured the spectra, masses, and widths of the K*(892)0 and φ(1020) resonances in Pb-Pb collisions at 2.76 TeV. These results, including RAA and the ratios of the integrated resonance yields to stable hadron yields, are presented and compared to results from other collision systems and to theoretical predictions.
Measurements of the yields of hadronic resonances (relative to non-resonances) in high-energy heavy-ion collisions allow the chemical freeze-out temperature and the time between chemical and thermal ...freeze-out of the collision system to be studied, while modifications to resonance masses and widths could be a signature of chiral symmetry restoration. The spectra (for pT < 5 GeV/c), total integrated yields, ratios to non-resonances (φ/π and φ/K), mass, and width of the φ(1020) meson and the uncorrected yields, mass, and width of the K*(892)0 and mesons have been measured using the ALICE detector for Pb-Pb collisions at TeV. These measurements will be compared to results from other collision systems and energies. Angular correlations between leading trigger hadrons and φ(1020) mesons have been measured in Pb-Pb and pp collisions; the mass and width of the φ(1020) meson as a function of the correlation angle will be presented.
Hadronic resonances at ALICE Knospe, A G
Journal of physics. Conference series,
01/2013, Volume:
446, Issue:
1
Journal Article
Peer reviewed
Open access
Measurements of the ratios of hadronic resonance yields to non-resonance yields can be used to study the properties of the hadronic phase of high-energy heavy-ion collisions. A change in resonance ...masses or widths could be an indication of chiral symmetry restoration. Measurements of resonances in proton-proton collisions provide an important baseline for measurements in heavy-ion collisions as well as data for tuning QCD-inspired particle production models. The ALICE collaboration has measured the K*(892)0 and φ(1020) resonances in Pb–Pb collisions at 2.76 TeV and the K*(892)0, φ(1020), and Σ*(1385)± resonances in pp collisions at 7 TeV. These measurements – including transverse momentum spectra, ratios to non-resonances, masses, and widths – are discussed and compared to theoretical predictions.
We study anisotropic spatial autocorrelation in differential synthetic aperture radar interferometric (dInSAR) measurements and its impact on geophysical parameter estimations. The dInSAR phase ...acquired by the satellite sensor is a superposition of different contributions, and when studying geophysical processes, we are usually only interested in the surface deformation part of the signal. Therefore, to obtain high-quality results, we would like to characterize and/or remove other phase components. A stochastic model has been found to be appropriate to describe atmospheric phase delay in dInSAR images. However, these phase delays are usually modeled as being isotropic, which is a simplification, because InSAR images often show directional atmospheric anomalies. Here, we analyze anisotropic structures and show validation results using both real and simulated data. We calculate experimental semivariograms of the dInSAR phase in several European Remote Sensing satellite-1/2 tandem interferograms. Based on the theory of random functions (RFs), we then fit anisotropic variogram models in the spatial domain, employing Mate¿rn- and Bessel-family correlation functions in nested models to represent complex dInSAR covariance structures. The presented covariance function types, in the statistical framework of stationary RFs, are consistent with tropospheric delay models. We find that by using anisotropic data covariance information to weight dInSAR measurements, we can significantly improve both the precision and accuracy of geophysical parameter estimations. Furthermore, the improvement is dependent on how similar the deformation pattern is to the dominant structure of the anisotropic atmospheric signals.
Heavy-flavor semileptonic decays are expected to dominate the spectrum of non-photonic electrons produced from collisions at the energies of the Relativistic Heavy Ion Collider. The non-photonic ...electron yield is suppressed by approximately a factor of 5 in central Au + Au events at
GeV relative to
p
+
p
events with the same collision energy. Most theoretical models predict less non-photonic-electron suppression than is observed experimentally. We present a preliminary measurement of the yield of non-photonic electrons in Cu + Cu events at
GeV, as well as the nuclear modification factor.
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