Studying the Quark Structure of the Proton in High Energy Proton-Proton Collisions at RHIC
Studying the Quark Structure of the Proton in High Energy Proton-Proton Collisions at RHIC

Author: Ruizhe Yang

Publisher:

Published: 2011

Total Pages:

ISBN-13:

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This thesis presents the first measurement of single spin asymmetries from inclusive di-hadron production in polarized proton-proton collisions at Relativistic Heavy Ion Collider. This measurement combines the transversity distribution function and a polarized di-hadron fragmentation function, therefore can be included in the global analysis as an independent measurement of quark transversity. Di-hadron single spin symmetries from currently available data sample are calculated for different ranges of invariant mass and transverse momentum of the pairs. Discussion of the results and projections of statistical uncertainties for future transverse running are presented.

New Aspects of High-Energy Proton-Proton Collisions
New Aspects of High-Energy Proton-Proton Collisions

Author: A. Ali

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 437

ISBN-13: 1461595401

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Articles focus on the planned European proton-proton collider, and concentrate on physics issues, rather than the more technical concerns addressed in the three previous workshops. The use of energies much higher than those of the American Superconducting Super Collider is featured. Topics include reviews of current projects, hadron collisions, lep

The Spin Structure of the Proton
The Spin Structure of the Proton

Author: Steven D. Bass

Publisher: World Scientific

Published: 2008

Total Pages: 212

ISBN-13: 9812709487

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One of the main challenges in nuclear and particle physics in the last 20 years has been to understand how the proton''s spin is built up from its quark and gluon constituents. Quark models generally predict that about 60% of the proton''s spin should be carried by the spin of the quarks inside, whereas high energy scattering experiments have shown that the quark spin contribution is small OCo only about 30%. This result has been the underlying motivation for about 1000 theoretical papers and a global program of dedicated spin experiments at BNL, CERN, DESY and Jefferson Laboratory to map the individual quark and gluon angular momentum contributions to the proton''s spin, which are now yielding exciting results. This book gives an overview of the present status of the field: what is new in the data and what can be expected in the next few years. The emphasis is on the main physical ideas and the interpretation of spin data. The interface between QCD spin physics and the famous axial U(1) problem of QCD (eta and etaprime meson physics) is also highlighted. Sample Chapter(s). Chapter 1: Introduction (159 KB). Contents: Spin Experiments and Data; Dispersion Relations and Spin Sum Rules; g 1 Spin Sum Rules; Fixed Poles; The Axial Anomaly, Gluon topology and g (0) A; Chiral Symmetry and Axial U(1) Dynamics; QCD Inspired Models of the Proton Spin Problem; The Spin-Flavour Structure of the Proton; QCD Fits to g 1 Data; Polarized Quark Distributions; Polarized Glue o g(x, Q 2 ); Transversity; Deeply Virtual Compton Scattering and Exclusive Processes; Polarized Photon Structure Functions; Conclusions and Open Questions: How Does the Proton Spin?. Readership: Academics, as well as physicists working on particle and nuclear physics at the interface of theory and experiment.

Studying the QCD Medium in Proton-proton Collisions Using PYTHIA
Studying the QCD Medium in Proton-proton Collisions Using PYTHIA

Author: Omar Tarek Elsherif

Publisher:

Published: 2017

Total Pages: 170

ISBN-13:

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Abstract: It is believed that in the first microsecond after the big bang, the universe was in a state known as the Quark-Gluon Plasma (QGP), where quarks and gluons were asymptotically free. Signatures of QGP like jet quenching and elliptic flow have been observed in heavy-ion collisions at RHIC and LHC experiments. The aim of this study was to investigate the possibility of QGP formation in proton-proton (p-p) collisions. PYTHIA was used to simulate the p-p collision at center-of-mass energies of √s = 200 GeV and √s = 13 TeV corresponding to the available energies of the current collider experiments. The ratios between the near-side and away-side yields associated with the high transverse momentum particles were calculated and compared for the low and high multiplicity events as a function of transverse momentum in order to search for such phase. For LHC energies at high multiplicity, away-side yields show suppression in comparison to near-side yields. This indicates that there is a possibility of creating QGP at high-energy high-multiplicity p-p collisions.

Nuclear Physics
Nuclear Physics

Author: National Research Council

Publisher: National Academies Press

Published: 1999-03-31

Total Pages: 222

ISBN-13: 0309173663

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Dramatic progress has been made in all branches of physics since the National Research Council's 1986 decadal survey of the field. The Physics in a New Era series explores these advances and looks ahead to future goals. The series includes assessments of the major subfields and reports on several smaller subfields, and preparation has begun on an overview volume on the unity of physics, its relationships to other fields, and its contributions to national needs. Nuclear Physics is the latest volume of the series. The book describes current activity in understanding nuclear structure and symmetries, the behavior of matter at extreme densities, the role of nuclear physics in astrophysics and cosmology, and the instrumentation and facilities used by the field. It makes recommendations on the resources needed for experimental and theoretical advances in the coming decade.

An Assessment of U.S.-Based Electron-Ion Collider Science
An Assessment of U.S.-Based Electron-Ion Collider Science

Author: National Academies of Sciences, Engineering, and Medicine

Publisher: National Academies Press

Published: 2018-10-13

Total Pages: 153

ISBN-13: 0309478561

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Understanding of protons and neutrons, or "nucleons"â€"the building blocks of atomic nucleiâ€"has advanced dramatically, both theoretically and experimentally, in the past half century. A central goal of modern nuclear physics is to understand the structure of the proton and neutron directly from the dynamics of their quarks and gluons governed by the theory of their interactions, quantum chromodynamics (QCD), and how nuclear interactions between protons and neutrons emerge from these dynamics. With deeper understanding of the quark-gluon structure of matter, scientists are poised to reach a deeper picture of these building blocks, and atomic nuclei themselves, as collective many-body systems with new emergent behavior. The development of a U.S. domestic electron-ion collider (EIC) facility has the potential to answer questions that are central to completing an understanding of atoms and integral to the agenda of nuclear physics today. This study assesses the merits and significance of the science that could be addressed by an EIC, and its importance to nuclear physics in particular and to the physical sciences in general. It evaluates the significance of the science that would be enabled by the construction of an EIC, its benefits to U.S. leadership in nuclear physics, and the benefits to other fields of science of a U.S.-based EIC.

Heavy-Quarkonium Production in High Energy Proton-Proton Collisions at RHIC.
Heavy-Quarkonium Production in High Energy Proton-Proton Collisions at RHIC.

Author:

Publisher:

Published: 2009

Total Pages: 4

ISBN-13:

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We update the study of the total [psi] and [Upsilon] production cross section in proton-proton collisions at RHIC energies using the QCD-based Color-Singlet (CS) Model, including next-to-leading order partonic matrix elements. We also include charm-quark initiated processes which appear at leading order in [alpha]{sub s}, but which have so far been overlooked in such studies. Contrary to earlier claims, we show that the CS yield is consistent with measurements over a broad range of J/[psi] rapidities. We also find that charm-quark initiated processes, including both intrinsic and sea-like charm components, typically contribute at least 20 % of the direct J/[psi] yield, improving the agreement with data both for the integrated cross section and its rapidity dependence. The key signature for such processes is the observation of a charm-quark jet opposite in azimuthal angle [phi] to the detected J/[psi]. Our results have impact on the proper interpretation of heavy-quarkonium production in heavy-ion collisions and its use as a probe for the quark-gluon plasma.

Quark Model and High Energy Collisions
Quark Model and High Energy Collisions

Author: Vladimir Vladislavovich Anisovich

Publisher: World Scientific

Published: 2004

Total Pages: 547

ISBN-13: 9812386998

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This is an updated version of the book published in 1985. QCD-motivated, it gives a detailed description of hadron structure and soft interactions in the additive quark model, where hadrons are regarded as composite systems of dressed quarks.In the past decade it has become clear that nonperturbative QCD, responsible for soft hadronic processes, may differ rather drastically from perturbative QCD. The understanding of nonperturbative QCD requires a detailed investigation of the experiments and the theoretical approaches. Bearing this in mind, the book has been rewritten paying special attention to the interplay of soft hadronic collisions and the quark model. It is at the crossroads of these domains that peculiar features of strong QCD reveal themselves.The book discusses constituent quarks, diquarks, the massive effective gluons and the problem of scalar isoscalar mesons. The quark-gluonium classification of meson states is also given. Experimentally observed properties of hadrons are presented together with the corresponding theoretical interpretation in the framework of the composite hadron structure.The text includes a large theoretical part, which shows how to treat composite systems (including relativistic ones) with a technique based on spectral integration. This technique provides the possibility of handling hadrons as weakly bound systems of quarks and, at the same time, takes into account confinement.Attention is focused on the composite structure revealing itself in high energy hadron collisions. Fields of applicability of the additive quark model are discussed, as is colour screening in hadronic collisions at high and superhigh energies. Along with a detailed presentation of hadron-hadron collisions, a description of hadron-nucleus collisions is given.

Dijet Angular Distributions in Proton-Proton Collisions
Dijet Angular Distributions in Proton-Proton Collisions

Author: Nele Boelaert

Publisher: Springer Science & Business Media

Published: 2011-10-26

Total Pages: 176

ISBN-13: 3642245978

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This thesis is based on the first data from the Large Hadron Collider (LHC) at CERN. Its theme can be described as the classical Rutherford scattering experiment adapted to the LHC: measurement of scattering angles to search for new physics and substructure. At the LHC, colliding quarks and gluons exit the proton collisions as collimated particle showers, or jets. The thesis presents studies of the scattering angles of these jets. It includes a phenomenological study at the LHC design energy of 14 TeV, where a model of so-called large extra dimensions is used as a benchmark process for the sensitivity to new physics. The experimental result is the first measurement, made in 2010, by ATLAS, operating at the LHC start-up energy of 7 TeV. The result is compatible with the Standard Model and demonstrates how well the physics and the apparatus are understood. The first data is a tiny fraction of what will be accumulated in the coming years, and this study has set the stage for performing these measurements with confidence as the LHC accumulates luminosity and increases its energy, thereby probing smaller length scales.

Studying the Spin Structure of the Proton Using the Solenoidal Tracker at RHIC.
Studying the Spin Structure of the Proton Using the Solenoidal Tracker at RHIC.

Author:

Publisher:

Published: 1998

Total Pages: 11

ISBN-13:

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The primary goal of RHIC is to produce nuclear matter under extremes of temperature and density sufficient to excite the QCD vacuum, resulting in the creation of a deconfined plasma of quarks and gluons. A second goal central to the RHIC scientific program is to advance the study of the spin structure of the proton significantly beyond what has been learned from deep inelastic scattering (DIS) measurements by studying spin asymmetries in strong processes involving the partonic constituents of polarized protons. After decades of being regarded as an inessential complication to the strong interaction at high energy, spin has again become a topic of considerable experimental and theoretical interest. This is largely due to the observation from DIS that the net contribution to the proton spin from the quark constituents ((approximately) 30%) is smaller than expected relative to the momentum carried in this sector. The RHIC accelerator will provide an unprecedented opportunity to fully explore the spin structure of the proton with high precision studies focused on measuring the spin-dependent parton distributions (valence quark, sea quark, gluon) of the proton. It is designed to operate both with high luminosity (1031--1032 cm−2 sec−1) and high polarization ((approximately) 70%). In addition, the energy range at RHIC ((square root)s = 200--500 GeV) is sufficiently high that spin effects in polarized proton interactions should be calculable once the spin structure of the proton is sufficiently understood. The experimental results will therefore provide a rigorous test of QCD. A further focus of the RHIC spin physics program will be to search for physics beyond the standard model. The increased sensitivity afforded by using polarized protons to study parity violation in inclusive jet production at high p{sub t} makes this exploration competitive with respect to ongoing searches using unpolarized beams.