Cold Nuclear Matter Effects on Quarkonium Production from the SPS to the LHC

Cold Nuclear Matter Effects on Quarkonium Production from the SPS to the LHC
Author:
Publisher:
Total Pages: 5
Release: 2009
Genre:
ISBN:
GET BOOK

Download Cold Nuclear Matter Effects on Quarkonium Production from the SPS to the LHC Book in PDF, Epub and Kindle

The J/?,???????? and?c production yields are expected to be considerably suppressed in a quark-gluon plasma. In addition, the? states, with the possible exception of the 1S state, are also expected to be suppressed. However, in proton-nucleus collisions all the quarkonium production cross sections scale less than linearly with the number of binary nucleon-nucleon collisions. These 'cold nuclear matter' effects need to be accounted for before signals of the high density QCD medium can be identified in the measurements made in nucleus-nucleus collisions. There are two cold nuclear matter effects important for midrapidity quarkonium production: 'nuclear absorption', a final-state effect, and shadowing, an initial-state effect. We characterize these effects and study their energy and rapidity dependence.

Cold Nuclear Matter Effects in J/[psi] Production

Cold Nuclear Matter Effects in J/[psi] Production
Author:
Publisher:
Total Pages: 6
Release: 2009
Genre:
ISBN:
GET BOOK

Download Cold Nuclear Matter Effects in J/[psi] Production Book in PDF, Epub and Kindle

Lattice QCD predicts that, above a certain critical energy density or temperature, strongly interacting matter undergoes a phase transition from the hadronic world to a quark-gluon plasma state, where the coloured quarks and gluons are no longer bound to colourless hadrons. The suppression of quarkonium production in high-energy nuclear collisions is one of the most interesting signatures of QGP formation, for two reasons: due to their large masses, charm and beauty quarks are created only in the initial hard scattering processes, before the QGP is formed; and the Q{bar Q} binding potential should be screened in the deconfined colour medium. Until the LHC starts colliding Pb nuclei, charm is the heaviest quark that can check the validity of the finite temperature QCD predictions, given the much smaller beauty production cross sections. However, the interpretation of the presently available results on charmonium suppression in heavy-ion collisions, obtained at the SPS and RHIC, is hampered by a multitude of other 'nuclear effects', which exist even in the absence of QGP formation, such as the badly understood nuclear modifications of the gluon distribution functions, the level of energy lost by the partons traversing the nuclei before producing the Q{bar Q} pair, the rate at which the nascent quarkonium state is broken up by the surrounding nuclear matter, etc. Fortunately, most of these 'cold nuclear matter' effects can be studied on the basis of proton-nucleus measurements. However, care must be taken when converting the p-A observations into a reference baseline that can be used in the analysis of the heavy-ion data. In particular, it has recently been shown [1] that it is wrong to assume that the rate of final-state Glauber-like J/[psi] absorption, usually called the 'J/[psi] absorption cross section', [sigma]{sub abs}{sup J/{psi}}, is independent of the collision energy and of the charmonium kinematics, as was previously assumed in the analysis of the SPS heavy-ion data.

Proceedings of RIKEN BNL Research Center Workshop

Proceedings of RIKEN BNL Research Center Workshop
Author:
Publisher:
Total Pages:
Release: 2011
Genre:
ISBN:
GET BOOK

Download Proceedings of RIKEN BNL Research Center Workshop Book in PDF, Epub and Kindle

Understanding the structure of the hadron is of fundamental importance in subatomic physics. Production of heavy quarkonia is arguably one of the most fascinating subjects in strong interaction physics. It offers unique perspectives into the formation of QCD bound states. Heavy quarkonia are among the most studied particles both theoretically and experimentally. They have been, and continue to be, the focus of measurements in all high energy colliders around the world. Because of their distinct multiple mass scales, heavy quarkonia were suggested as a probe of the hot quark-gluon matter produced in heavy-ion collisions; and their production has been one of the main subjects of the experimental heavy-ion programs at the SPS and RHIC. However, since the discovery of J/psi at Brookhaven National Laboratory and SLAC National Accelerator Laboratory over 36 years ago, theorists still have not been able to fully understand the production mechanism of heavy quarkonia, although major progresses have been made in recent years. With this in mind, a two-week program on quarkonium production was organized at BNL on June 6-17, 2011. Many new experimental data from LHC and from RHIC were presented during the program, including results from the LHC heavy ion run. To analyze and correctly interpret these measurements, and in order to quantify properties of the hot matter produced in heavy-ion collisions, it is necessary to improve our theoretical understanding of quarkonium production. Therefore, a wide range of theoretical aspects on the production mechanism in the vacuum as well as in cold nuclear and hot quark-gluon medium were discussed during the program from the controlled calculations in QCD and its effective theories such as NRQCD to various models, and to the first principle lattice calculation. The scientific program was divided into three major scientific parts: basic production mechanism for heavy quarkonium in vacuum or in high energy elementary collisions; the formation of quarkonium in nuclear medium as well as the strong interacting quark-gluon matter produced in heavy ion collisions; and heavy quarkonium properties from the first principle lattice calculations. The heavy quarkonium production at a future Electron-Ion Collider (EIC) was also discussed at the meeting. The highlight of the meeting was the apparent success of the NRQCD approach at next-to-leading order in the description of the quarkonium production in proton-proton, electron-proton and electron positron collisions. Still many questions remain open in lattice calculations of in-medium quarkonium properties and in the area of cold nuclear matter effects.

Cold Nuclear Matter Effects on J/psi and Upsilon Production at the LHC.

Cold Nuclear Matter Effects on J/psi and Upsilon Production at the LHC.
Author:
Publisher:
Total Pages: 24
Release: 2009
Genre:
ISBN:
GET BOOK

Download Cold Nuclear Matter Effects on J/psi and Upsilon Production at the LHC. Book in PDF, Epub and Kindle

The charmonium yields are expected to be considerably suppressed if a deconfined medium is formed in high-energy heavy-ion collisions. In addition, the bottomonium states, with the possible exception of the [Upsilon](1S) state, are also expected to be suppressed in heavy-ion collisions. However, in proton-nucleus collisions the quarkonium production cross sections, even those of the [Upsilon](1S), scale less than linearly with the number of binary nucleon-nucleon collisions. These 'cold nuclear matter' effects need to be accounted for before signals of the high density QCD medium can be identified in the measurements made in nucleus-nucleus collisions. We identify two cold nuclear matter effects important for midrapidity quarkonium production: 'nuclear absorption', typically characterized as a final-state effect on the produced quarkonium state and shadowing, the modification of the parton densities in nuclei relative to the nucleon, an initial-state effect. We characterize these effects and study their energy and rapidity dependence.

Cold Nuclear Matter Effects on J/psi-->e+e- and Psi'-->;e+e- Production in D+Au Collisions at 200 Gev

Cold Nuclear Matter Effects on J/psi-->e+e- and Psi'-->;e+e- Production in D+Au Collisions at 200 Gev
Author: Darren McGlinchey
Publisher:
Total Pages:
Release: 2012
Genre: Nuclear physics
ISBN:
GET BOOK

Download Cold Nuclear Matter Effects on J/psi-->e+e- and Psi'-->;e+e- Production in D+Au Collisions at 200 Gev Book in PDF, Epub and Kindle

ABSTRACT: Mesons composed of heavy quark-antiquark pairs, known as quarkonia, provide the only direct probe of the screening length in the deconfined state of quarks and gluons, known as the quark gluon plasma (QGP), which is believed to be produced in high energy heavy ion collisions. However, the observation of suppression of quarkonia production in heavy ion collisions at high energies is complicated by the modification of quarkonia production in normal nuclear matter. Measuring the modification of quarkonia production due to the effects of normal nuclear matter, often termed cold nuclear matter (CNM) effects, provide a critical baseline for understanding the properties of the QGP. Measurements of CNM effects on quarkonia production are also interesting in their own right, and can be measured independently in proton-nucleus (p+A) collisions. The modification of quarkonia production in p+A collisions provides insight into quarkonia production mechanisms unavailable through the study of proton-proton collisions alone. The study of quarkonia production in p+A collisions over a wide range of kinematic variables can also provide constraints on the modification of parton distribution functions in nuclei. In order to quantify the CNM effects present at the Relativistic Heavy Ion Collider (RHIC), the PHENIX experiment has recorded data on d+Au collisions at \sqsn=200 GeV. The analysis of J/psi→e+e- and psi'→e+e- production from that data set is presented here. Both J/psi and psi' production are found to be suppressed in d+Au relative to p+p collisions, with the suppression increasing for collisions with small impact parameters. The psi' production is found to be much more suppressed than J/psi production, a result which is unexpected based on measurements at lower collision energy and present theoretical pictures. A parametrization of the J/psi modification measured by PHENIX in terms of two CNM effects is also presented. One is the nuclear breakup of the forming quarkonium state through collisions with nucleons during the d+Au collision. The other is the modification of the gluon distribution in the Au nucleus. It is found that the two effects can be separated due to the very different impact parameter dependencies. A strongly non-linear geometric dependence on the modification of the gluon distribution function is observed, with the modification found to be concentrated near the center of the Au nucleus. This parametrization is also used to estimate the modification of J/psi production in Au+Au collisions due to CNM effects. This modification is compared to PHENIX measurements of J/psi production in Au+Au collisions. Suppression of J/psi production in Au+Au collisions beyond CNM effects is observed. This excess suppression is interpreted as suppression of J/psi production due to the formation of a QGP.

Quark-gluon Plasma 5

Quark-gluon Plasma 5
Author: Xin-nian Wang
Publisher: World Scientific
Total Pages: 416
Release: 2016-01-21
Genre: Science
ISBN: 9814663727
GET BOOK

Download Quark-gluon Plasma 5 Book in PDF, Epub and Kindle

This is the fifth volume in the series on the subject of quark-gluon plasma, a unique phase created in heavy-ion collisions at high energy. It contains review articles by the world experts on various aspects of quark-gluon plasma taking into account the advances driven by the latest experimental data collected at both the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC). The articles are pedagogical and comprehensive which can be helpful for both new researchers entering the field as well as the experienced physicists working on the subject.

Quark-gluon Plasma Five

Quark-gluon Plasma Five
Author:
Publisher: World Scientific
Total Pages: 416
Release: 2016
Genre: Science
ISBN: 9814663719
GET BOOK

Download Quark-gluon Plasma Five Book in PDF, Epub and Kindle

"This is the fifth volume in the series on the subject of quark-gluon plasma, a unique phase created in heavy-ion collisions at high energy. It contains review articles by the world experts on various aspects of quark-gluon plasma taking into account the advances driven by the latest experimental data collected at both the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC). The articles are pedagogical and comprehensive which can be helpful for both new researchers entering the field as well as the experienced physicists working on the subject."--

Quark Gluon Plasma and Cold Nuclear Matter Modification of Y States at [square Root][superscript S]NN

Quark Gluon Plasma and Cold Nuclear Matter Modification of Y States at [square Root][superscript S]NN
Author: Santona Tuli
Publisher:
Total Pages:
Release: 2019
Genre:
ISBN: 9781658413558
GET BOOK

Download Quark Gluon Plasma and Cold Nuclear Matter Modification of Y States at [square Root][superscript S]NN Book in PDF, Epub and Kindle

Quantum chromodynamics describes the phases of strongly-interacting matter and their boundaries, including the deconfined quark-gluon plasma (QGP) phase reached in the high energy density regime. Properties of the QGP are studied using ultrarelativistic collisions of fully-ionized heavy nuclei, which also exhibit (cold) nuclear matter properties unrelated to the plasma. An indicator of the QGP temperature is the modification of quarkonium production in collisions between two heavy ions relative to collisions between two protons. The modification in collisions between a heavy ion and a proton, where the QGP is typically not produced but nuclear matter is abundant, provides an essential baseline. Production cross sections of Y(1S), Y(2S), and Y(3S) mesons decaying into [mu]+[mu]− in proton-lead (pPb) collisions are measured using data collected by the CMS experiment at [square root][superscript s]NN = 5.02 TeV. Nuclear modification factors R[subscript pPb] for all three Y states, obtained using measured proton-proton (pp) cross sections at the same collision energy, show that Y states are suppressed in pPb collisions compared to pp collisions. Sequential ordering of the Y R[subscript pPb], with Y(1S) least suppressed and Y(3S) most suppressed, indicates presence of final- state modification of Y mesons in pPb collisions. The R[subscript pPb] of individual Y states are found to be consistent with constant values when studied as functions of transverse momentum and center-of-mass rapidity. Predictions using the final-state comover interaction model, which incorporates sequential suppression of bottomonia in pPb, are found to be in better agreement with the measured R[subscript pPb] versus rapidity than predictions using initial-state mod- ification models. Nuclear modification is less pronounced in pPb collisions than in lead-lead collisions, where the additional lead nucleus and QGP effects result in greater Y suppression. Forward-backward production ratios R[subscript FB] of Y states, which help investigate regions of different nuclear matter densities, are found to be consistent with unity and constant with increasing event activity measured both far away from and near to the measured Y.

Estimating Cold Nuclear Matter Effects Using Jets in P-Pb Collisions At {591}sNN

Estimating Cold Nuclear Matter Effects Using Jets in P-Pb Collisions At {591}sNN
Author: Christopher Ghanim Yaldo
Publisher:
Total Pages: 162
Release: 2015
Genre: Cold fusion
ISBN:
GET BOOK

Download Estimating Cold Nuclear Matter Effects Using Jets in P-Pb Collisions At {591}sNN Book in PDF, Epub and Kindle

In heavy-ion collisions at RHIC and the LHC, a suppression of the nuclear modification factor for jets along with other strongly interacting particles has been observed relative to proton-proton collisions. To unambiguously determine if this suppression is due to the creation of a strongly interacting medium of de-confied partons referred to as the Quark-Gluon Plasma, or due to Cold Nuclear Matter effects, a "control experiment" is required. Proton-lead collisions serve as this control experiment, because these colli- sions are expected to be sensitive to cold nuclear matter effects while not producing a QGP at this collision energy ({591}sNN = 5.02 TeV). Presented in this defense are the first measurements of charged + neutral jets in p-Pb collisions using the ALICE detector at the LHC. Measurements of CNM effects are done via the nuclear modification factor for jets: RpPb, RCP, and the jet structure ratio. Measurements of the jet spectrum along with a detailed and proper discussion of the statistical, systematic, and normalization uncertain- ties will be presented. Also a comparison of RpPb and RCP measured in this analysis to other measured RpPb and RCP from ATLAS and CMS will be presented. All the measurements performed in this analysis indicate that no strong cold nuclear matter effects are observed in p-Pb collisions using the ALICE detector at the LHC.