| 1. |
- Abelev, Betty, et al.
(författare)
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Long-range angular correlations on the near and away side in p-Pb collisions at root S-NN=5.02 TeV
- 2013
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 719:1-3, s. 29-41
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Tidskriftsartikel (refereegranskat)abstract
- Angular correlations between charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV for transverse momentum ranges within 0.5 < P-T,P-assoc < P-T,P-trig < 4 GeV/c. The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity, and expressed as associated yield per trigger particle. Two long-range ridge-like structures, one on the near side and one on the away side, are observed when the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. The excess on the near-side is qualitatively similar to that recently reported by the CMS Collaboration, while the excess on the away-side is reported for the first time. The two-ridge structure projected onto azimuthal angle is quantified with the second and third Fourier coefficients as well as by near-side and away-side yields and widths. The yields on the near side and on the away side are equal within the uncertainties for all studied event multiplicity and p(T) bins, and the widths show no significant evolution with event multiplicity or p(T). These findings suggest that the near-side ridge is accompanied by an essentially identical away-side ridge. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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| 2. |
- Abelev, Betty, et al.
(författare)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :11
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Tidskriftsartikel (refereegranskat)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 3. |
- Abelev, Betty, et al.
(författare)
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Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.
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| 4. |
- Addazi, Andrea, et al.
(författare)
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Cosmology from Strong Interactions
- 2022
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Ingår i: Universe. - : MDPI AG. - 2218-1997. ; 8:9
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Forskningsöversikt (refereegranskat)abstract
- A wealth of theoretical and phenomenological information about Quantum Chromodynamics at short and long distances collected so far in major collider measurements has profound implications in cosmology. In this review, we give a brief discussion of major implications of strongly-coupled dynamics of quarks and gluons and effects of their collective motion in physics of early Universe and in astrophysics.
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| 5. |
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| 6. |
- Flach Basso, Eduardo, et al.
(författare)
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Drell-Yan phenomenology in the color dipole picture revisited
- 2016
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Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-7998. ; 93:3
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Tidskriftsartikel (refereegranskat)abstract
- An extensive phenomenological study of the Drell-Yan (DY) process in pp collisions at various energies is performed in the color dipole framework. Besides previously studied γ∗ production we also include the Z0 contribution relevant at large dilepton invariant masses. We investigate the DY cross section differential in invariant mass, rapidity and transverse momentum of the dilepton pair in pp collisions at the RHIC and LHC. We consider three different phenomenological models for the dipole cross section and find a reasonable agreement with the available data. As a further test of the color dipole formalism, we also study the correlation function in azimuthal angle between the dilepton pair and a forward pion Δφ for different energies, dilepton rapidities and invariant masses. The characteristic double-peak structure of the correlation function around Δφ≃π found for very forward pions and low-mass dilepton pairs is sensitive to the saturation effects and can be tested by future DY measurements in pp collisions.
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| 7. |
- Flach Basso, Eduardo, et al.
(författare)
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Study of dilepton production in association with leading hadron at RHIC and LHC energies
- 2015
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Ingår i: Proceedings of Science. - 1824-8039.
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that current experimental data on γ/Z0 and heavy quarkonium production in pp collisions at RHIC and LHC energies can be described by the color dipole formalism. Three different phenomenological models based on saturation physics are used to estimate the Drell-Yan (DY) dilepton spectra in such processes. In order to further constrain QCD dynamics we suggest to measure the azimuthal correlation function C(Δφ) between mid-rapidity DY pairs and central/forward pions. On the other hand, this is a key background for C-odd heavy quarkonia (e.g. J/Φ and ϒ) production at high pT's which can be accompanied by a high-pT hadron from fragmentation of an additional gluon according to the Color-Singlet model (CSM). As a first step, we have estimated the transverse momentum distributions J/Φ; and ϒ in the dipole CSM and found a reasonable agreement with data at various energies. Similarly to the DY case we suggest to study correlations between a high-pT jet and J/Φ or ϒ in the dilepton channel at mid-rapidities.
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| 8. |
- Goncalves, Victor P., et al.
(författare)
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Isolated photon production and pion-photon correlations in high-energy pp and pA collisions
- 2020
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Ingår i: Physical Review D. - 2470-0010. ; 101:9
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Tidskriftsartikel (refereegranskat)abstract
- A phenomenological study of the isolated photon production in high energy pp and pA collisions at RHIC and LHC energies is performed. Using the color dipole approach we investigate the production cross section differential in the transverse momentum of the photon considering three different phenomenological models for the universal dipole cross section. We also present the predictions for the rapidity dependence of the ratio of pA to pp cross sections. As a further test of the formalism, for different energies and photon rapidities we analyze the correlation function in azimuthal angle Δφ between the photon and a forward pion. The characteristic double-peak structure of the correlation function around Δφ≃π observed previously for Drell-Yan pair production is found for an isolated photon emitted into the forward rapidity region which can be tested by future experiments.
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| 9. |
- Lima, Yuri N., et al.
(författare)
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Isolated photon production in the color dipole picture
- 2021
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Ingår i: Proceedings of Science. - 1824-8039. ; 408
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Konferensbidrag (refereegranskat)abstract
- A phenomenological study of the isolated photon production in high energy pp and pA collisions at RHIC and LHC energies is performed. Using the color dipole formalism, we investigate the impact of the saturation effects on the production cross sections considering three different phenomenological models for the universal dipole cross section. Predictions for the rapidity dependence of the ratio of pA to pp cross sections are also presented. Moreover, we present our predictions for the correlation function in azimuthal angle Δφ between the photon and a forward pion for different energies and photon rapidities. Our results demonstrate that the presence of saturation effects implies a double-peak structure in the correlation function around Δφ≃ π when the isolated photon and the pion are produced at forward rapidities.
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| 10. |
- Pasechnik, Roman, et al.
(författare)
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Different faces of confinement
- 2021
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Ingår i: Universe. - : MDPI AG. - 2218-1997. ; 7:9
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Forskningsöversikt (refereegranskat)abstract
- In this review, we provide a short outlook of some of the current most popular pictures and promising approaches to non-perturbative physics and confinement in gauge theories. A qualitative and by no means exhaustive discussion presented here covers such key topics as the phases of QCD matter, the order parameters for confinement, the central vortex and monopole pictures of the QCD vacuum structure, fundamental properties of the string tension, confinement realisations in gauge-Higgs and Yang–Mills theories, magnetic order/disorder phase transition, among others.
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| 11. |
- Pasechnik, Roman, et al.
(författare)
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Phenomenological review on quark-gluon plasma : Concepts vs. Observations
- 2017
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Ingår i: Universe. - : MDPI AG. - 2218-1997. ; 3:1
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Forskningsöversikt (refereegranskat)abstract
- In this review, we present an up-to-date phenomenological summary of research developments in the physics of the Quark-Gluon Plasma (QGP). A short historical perspective and theoretical motivation for this rapidly developing field of contemporary particle physics is provided. In addition, we introduce and discuss the role of the quantum chromodynamics (QCD) ground state, non-perturbative and lattice QCD results on the QGP properties, as well as the transport models used to make a connection between theory and experiment. The experimental part presents the selected results on bulk observables, hard and penetrating probes obtained in the ultra-relativistic heavy-ion experiments carried out at the Brookhaven National Laboratory Relativistic Heavy Ion Collider (BNL RHIC) and CERN Super Proton Synchrotron (SPS) and Large Hadron Collider (LHC) accelerators. We also give a brief overview of new developments related to the ongoing searches of the QCD critical point and to the collectivity in small (p + p and p + A) systems.
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| 12. |
- Pasechnik, Roman, et al.
(författare)
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Quantum Chromodynamics in the Early Universe : The Color Glass Condensate
- 2024
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Ingår i: Proceedings of Science. - 1824-8039. ; 441
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Konferensbidrag (refereegranskat)abstract
- Quantum chromodynamics (QCD), the basic theory of strong interactions between the quarks and gluons is expected to play an important role in the early universe. We discuss the scenario when the fast cooling of QCD matter leads to the creation of a saturated phase with an enormous number of possible configurations. Using an analogy with the classical glasses we predict that this glassy form of matter - the Glasma - existing at temperatures above a few GeV has dominated properties of the universe in the period preceding the formation of quark-gluon plasma (QGP). We examine the possibility that the properties of this high-temperature color-glass condensate (CGC) filling the universe in the very hot QCD and EW eras, and beyond were close to the stiff matter.
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| 13. |
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