Strangeness Enhancement in High Multiplicity Proton-proton Collisions at √s

Strangeness Enhancement in High Multiplicity Proton-proton Collisions at √s
Author: Plamen Rumenov Petrov
Publisher:
Total Pages:
Release: 2013
Genre:
ISBN:

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ALICE is one of the seven experiments at the Large Hadron Collider (LHC) at CERN, dedicated to the physics of heavy-ion collisions and, in particular, the properties of the Quark Gluon Plasma (QGP). IN addition to studying Pb-Pb collisions at \(\sqrt{sNN}\) = 2.76 TeV, ALICE has an extensive proton-proton (p-p) programme (\(\sqrt{s}\) = 0.9, 2.76, 7 and 8 TeV) aimed to provide a base for comparison with the Pb-Pb data as well as to complement the research in areas where ALICE is competitive with the other LHC experiments. Of particular interest for the ALICE collaboration are the high-multiplicity p-p events. As suggested by the Bjorken formula for the initial energy density in high energy collisions, such events could create conditions comparable to those in heavy-ion collisions at RHIC where the formation of the QGP has been observed. The identified charged hadron spectra in p-p collisions at \(\sqrt{s}\) = 7 TeV have been measured as a function of the event multiplicity, looking for signs of strangeness enhancement as one of the established signatures for the QGP formation. The analysis entails processing a sample of ~ 80 M minimum-bias and ~ 5 M high-multiplicity triggered p-p events. Three different particle identification techniques have been developed and assessed for the purpose of measuring the pion, kaon and proton yields over a momentum range of 0.2 GeV/c \(\leq\) pT \(\leq\) 2.5 GeV /c. A study of the systematic effects and the results are presented, including pT spectra and integrated yields for pions, kaons and protons, K \( \pm\)/\(\Pi\)\( \pm\) and p\( \pm\)/\(\Pi\)\( \pm\) ratios as a function of multiplicity, and a comparison to recent models. No significant variation in the particle ratios is observed up to multiplicities of the order of dN\(_{ch}\)/d\(\eta\) \(\approx\) 42.

The XVIII International Conference on Strangeness in Quark Matter (SQM 2019)

The XVIII International Conference on Strangeness in Quark Matter (SQM 2019)
Author: Domenico Elia
Publisher: Springer Nature
Total Pages: 568
Release: 2020-10-03
Genre: Science
ISBN: 3030534480

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This book focuses on new experimental and theoretical advances concerning the role of strange and heavy-flavour quarks in high-energy heavy-ion collisions and in astrophysical phenomena. The topics covered include • Strangeness and heavy-quark production in nuclear collisions and hadronic interactions, • Hadron resonances in the strongly-coupled partonic and hadronic medium, • Bulk matter phenomena associated with strange and heavy quarks, • QCD phase structure, • Collectivity in small systems, • Strangeness in astrophysics,• Open questions and new developments.

The Large Hadron Collider

The Large Hadron Collider
Author: Lyndon R. Evans
Publisher: EPFL Press
Total Pages: 264
Release: 2009-01-01
Genre: Hadron colliders
ISBN: 9782940222346

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Describes the technology and engineering of the Large Hadron collider (LHC), one of the greatest scientific marvels of this young 21st century. This book traces the feat of its construction, written by the head scientists involved, placed into the context of the scientific goals and principles.

Search for New Physics in Events with High Jet Multiplicity and Low Missing Transverse Momentum in Proton-proton Collisions at $\sqrt{s}

Search for New Physics in Events with High Jet Multiplicity and Low Missing Transverse Momentum in Proton-proton Collisions at $\sqrt{s}
Author:
Publisher:
Total Pages:
Release: 2016
Genre:
ISBN:

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A dedicated search is presented for new phenomena in inclusive eight- and ten-jet final states with low missing transverse momentum, with and without identification of jets originating from b quarks. The analysis is based on data from proton-proton collisions corresponding to an integrated luminosity of 19.6 inverse femtobarns collected with the CMS detector at the LHC at sqrt(s) = 8 TeV. The dominant multijet background expectations are obtained from low jet multiplicity control samples. Data agree well with the standard model background predictions, and limits are set in several benchmark models. Colorons (axigluons) with masses between 0.6 and 0.75 (up to 1.15) TeV are excluded at 95% confidence level. Similar exclusion limits for gluinos in R-parity violating supersymmetric scenarios are from 0.6 up to 1.1TeV. These results comprise the first experimental probe of the coloron and axigluon models in multijet final states.

Momentum Distributions

Momentum Distributions
Author: Richard N. Silver
Publisher: Springer Science & Business Media
Total Pages: 400
Release: 2013-11-11
Genre: Science
ISBN: 1489925546

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This volume presents the proceedings of the Workshop on Momentum Distributions held on October 24 to 26, 1988 at Argonne National Laboratory. This workshop was motivated by the enormous progress within the past few years in both experimental and theoretical studies of momentum distributions, by the growing recognition of the importance of momentum distributions to the characterization of quantum many-body systems, and especially by the realization that momentum distribution studies have much in common across the entire range of modern physics. Accordingly, the workshop was unique in that it brought together researchers in nuclear physics, electronic systems, quantum fluids and solids, and particle physics to address the common elements of momentum distribution studies. The topics dis cussed in the workshop spanned more than ten orders of magnitude range in charac teristic energy scales. The workshop included an extraordinary variety of interactions from Coulombic to hard core repulsive, from non-relativistic to extreme relativistic.

Strange Particle Production in Pp Collisions at Sqrt(s)

Strange Particle Production in Pp Collisions at Sqrt(s)
Author:
Publisher:
Total Pages: 38
Release: 2011
Genre:
ISBN:

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The spectra of strange hadrons are measured in proton-proton collisions, recorded by the CMS experiment at the CERN LHC, at centre-of-mass energies of 0.9 and 7 TeV. The K0_s, Lambda, and Xi-̂ particles and their antiparticles are reconstructed from their decay topologies and the production rates are measured as functions of rapidity and transverse momentum. The results are compared to other experiments and to predictions of the PYTHIA Monte Carlo program. The transverse momentum distributions are found to differ substantially from the PYTHIA results and the production rates exceed the predictions by up to a factor of three.

Femtoscopy of Proton-proton Collisions in the ALICE Experiment

Femtoscopy of Proton-proton Collisions in the ALICE Experiment
Author: Nicolas Bock
Publisher:
Total Pages: 79
Release: 2011
Genre:
ISBN:

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Abstract: The Large Ion Collider Experiment (ALICE) at CERN has been designed to study matter at extreme conditions of temperature and pressure, with the long term goal of observing deconfined matter (free quarks and gluons), study its properties and learn more details about the phase diagram of nuclear matter. The ALICE experiment provides excellent particle tracking capabilities in high multiplicity proton-proton and heavy ion collisions, allowing to carry out detailed research of nuclear matter. This dissertation presents the study of the space time structure of the particle emission region, also known as femtoscopy, in proton-proton collisions at 0.9, 2.76 and 7.0 TeV. The emission region can be characterized by taking advantage of the Bose-Einstein effect for identical particles, which causes an enhancement of produced identical pairs at low relative momentum. The geometry of the emission region is related to the relative momentum distribution of all pairs by the Fourier transform of the source function, therefore the measurement of the final relative momentum distribution allows to extract the initial space-time characteristics. Results show that there is a clear dependence of the femtoscopic radii on event multiplicity as wellas transverse momentum, a signature of the transition of nuclear matter into its fundamental components and also of strong interaction among these. The present work also considers a physics motivated parametrization of non-femtoscopic correlations to characterize the background signal. It is shown that at these high energies and multiplicities this parametrization does not work as it does for lower energies. A special chapter containing the detailed study of possible signatures of black hole formation is also presented.