arXiv subjects

Gary R. Goldstein

Publications and source records attributed to Gary R. Goldstein.

At least 55 records · Page 3Linked to original sources

arXiv2007

Dick Dalitz: Examples of His Contributions to Particle Physics

Dick Dalitz produced lasting contributions to particle physics for 50 years. Along with Dalitz pairs, Dalitz plots and CDD poles, he did major work in parity violation, hyperon resonance identification, the quark model, and hypernuclei. These topics will be summarized, with some emphasis on the author's collaboration with Dalitz on quark spin and fragmentation correlations, and, particularly, the work on the identification of the top quark and its mass. Short biographical information is interspersed. This paper is based on a presentation at the International School of Subnuclear Physics, Erice 2006.

physics.hist-ph↗

arXiv2005

Transversity Properties of Quarks and Hadrons in SIDIS and Drell-Yan

We consider the leading twist $T$-odd contributions as the dominant source of the azimuthal and transverse single spin asymmetries in SIDIS and dilepton production in Drell-Yan Scattering. These asymmetries contain information on the distribution of quark transverse spin in (un)polarized protons. In the spectator framework we estimate these asymmetries at HERMES kinematics and at $50\ {\rm GeV}$ for the proposed experiments at GSI, where an anti-proton beam is ideal for studying the transversity properties of quarks due to the dominance of {\em valence} quark effects.

hep-ph↗

arXiv2005

$T$-Odd Effects in Unpolarized Drell-Yan Scattering

We consider the leading twist $T$-odd contributions as the dominant source of the $\cos 2ϕ$ azimuthal asymmetry in unpolarized $p\bar{p}\to μμ^+ X$ dilepton production in Drell-Yan Scattering. This asymmetry contains information on the distribution of quark transverse spin in an unpolarized proton. In a parton-spectator framework we estimate these asymmetries at $50 {\rm GeV}$ center of mass energy. This azimuthal asymmetry is interesting in light of proposed experiments at GSI, where an anti-proton beam is ideal for studying the transversity properties of quarks due to the dominance of {\em valence} quark effects.

hep-ph↗

arXiv2004

Novel Azimuthal Asymmetries in Drell Yan and Semi-inclusive Deep Inelastic Scattering

We consider the leading and sub-leading twist $T$-odd and even contributions to the $\cos 2ϕ$ azimuthal asymmetry in unpolarized dilepton production in Drell-Yan Scattering. We estimate the contributions' effects at $500 {\rm GeV}$, $ 50 {\rm GeV}$, and $25 {\rm GeV}$ energies in the framework of the parton model using a quark diquark-spectator model of the nucleon to approximate the soft contributions.

hep-ph↗

arXiv2003

Novel Transversity Properties in SIDIS

We consider a rescattering mechanism to calculate a leading twist $T$-odd pion fragmentation function, a candidate for filtering the transversity properties of the nucleon. We evaluate the single spin azimuthal asymmetry for a transversely polarized target in semi-inclusive deep inelastic scattering (for HERMES kinematics) and the double $T$-odd $\cos2ϕ$ asymmetry in this framework.

hep-ph↗

arXiv2003

Nucleon Transversity Properties Through ep Scattering

The T-odd distribution functions contributing to transversity properties of the nucleon and their role in fueling nontrivial contributions to azimuthal asymmetries in semi-inclusive deep inelastic scattering are investigated. We use a dynamical model to evaluate these quantities in terms of HERMES kinematics. We point out how the measurements of cos(2phi) asymmetry may indicate the presence of T-odd structures in unpolarized ep scattering.

hep-ph↗

arXiv2003

A mechanism for the T-odd pion fragmentation function

We consider a simple rescattering mechanism to calculate a leading twist $T$-odd pion fragmentation function, a favored candidate for filtering the transversity properties of the nucleon. We evaluate the single spin azimuthal asymmetry for a transversely polarized target in semi-inclusive deep inelastic scattering (for HERMES kinematics). Additionally, we calculate the double $T$-odd $\cos2ϕ$ asymmetry in this framework.

hep-ph↗

arXiv2003

Novel Transversity Properties in Semi-Inclusive Deep Inelastic Scattering

The $T$-odd distribution functions contributing to transversity properties of the nucleon and their role in fueling nontrivial contributions to azimuthal asymmetries in semi-inclusive deep inelastic scattering are investigated. We use a dynamical model to evaluate these quantities in terms of HERMES kinematics.

hep-ph↗

arXiv2002

Transversity in Exclusive and Inclusive Processes

Both meson photoproduction and semi-inclusive deep inelastic scattering can potentially probe transversity properties of the nucleon. We explore how that potential can be realized dynamically. The role of rescattering in both exclusive and inclusive meson production as a source for single spin asymmetries is examined. Using a dynamical model, we evaluate the spin independent $\cos 2ϕ$ asymmetry associated with transversity of quarks inside unpolarized hadrons, at HERMES kinematics. We also explore the effects of rescattering on the transversity distribution of the nucleon.

hep-ph↗

arXiv2002

Transversity and Meson Photoproduction

Both meson photoproduction and semi-inclusive deep inelastic scattering can potentially probe transversity in the nucleon. We explore how that potential can be realized dynamically. The role of rescattering in both exclusive and inclusive meson production as a source for transverse polarization asymmetry is examined. We use a dynamical model to calculate the asymmetry and relate that to the transversity distribution of the nucleon.

hep-ph↗

arXiv2002

Flavor-Spin Symmetry and the Tensor Charge

Exploiting an approximate phenomenological symmetry of the $J^{PC}=1^{+-}$ light axial vector mesons and using pole dominance, we calculate the flavor contributions to the nucleon tensor charge. The result depends on the decay constants of the axial vector mesons and their couplings to the nucleons.

hep-ph↗

arXiv2001

The Chiral Odd Nucleon Tensor Charge

Exploiting the phenomenological symmetry of the $J^{PC}=1^{+-}$ light axial vector mesons and using pole dominance, we calculate the flavor contributions to the nucleon tensor charge.

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arXiv2001

A Determination of the Nucleon Tensor Charge

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arXiv2001

Flavor-Spin Symmetry Estimate of the Nucleon Tensor Charge

The axial vector and tensor charge, defined as the first moments of the forward nucleon matrix elements of corresponding quark currents, are essential for characterizing the spin structure of the nucleon. However, the transversity distribution and thus the tensor charge decouple at leading twist in deep inelastic scattering, making them hard to measure. Additionally, the non-conservation of the tensor charge makes it difficult to predict. There are no definitive theoretical predictions for the tensor charge, aside from several model dependent calculations. We present a new approach that exploits the approximate mass degeneracy of the light axial vector mesons ($a_1$(1260), $b_1$(1235) and $h_1$(1170)) and uses pole dominance to calculate the tensor charge. The result is simple in form. It depends on the decay constants of the axial vector mesons and their couplings to the nucleons, along with the average transverse momentum of the quarks in the nucleon.

hep-ph↗

arXiv2001

Estimates of the Nucleon Tensor Charge

Like the axial vector charges, defined from the forward nucleon matrix element of the axial vector current on the light cone, the nucleon tensor charge, defined from the corresponding matrix element of the tensor current, is essential for characterizing the momentum and spin structure of the nucleon. Because there must be a helicity flip of the struck quark in order to probe the transverse spin polarization of the nucleon, the transversity distribution (and thus the tensor charge) decouples at leading twist in deep inelastic scattering, although no such suppression appears in Drell-Yan processes. This makes the tensor charge difficult to measure and its non-conservation makes its prediction model dependent. We present a different approach. Exploiting an approximate SU(6)xO(3) symmetric mass degeneracy of the light axial vector mesons (a1(1260), b1(1235) and h1(1170)) and using pole dominance, we calculate the tensor charge. The result is simple in form and depends on the decay constants of the axial vector mesons and their couplings to the nucleons, along with the average transverse momentum of the quarks in the nucleon. The result is compared with other model estimates.

hep-ph↗

arXiv2000

Spin Dependent Fragmentation Functions for Heavy Flavor Baryons and Single Heavy Hyperon Polarization

Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. $Λ_b$ , $Λ_c$ and $Ξ_c$ production rate and polarization at LEP energies are calculated and, where possible, compared with experiment. A different approach, also relying on a heavy quark-diquark model, is proposed for the small momentum transfer inclusive production of polarized heavy flavor hyperons. The predicted $Λ_c$ polarization is roughly in agreement with experiment.

hep-ph↗

arXiv2000

Excited State Contributions to the Heavy Baryon Fragmentation Functions in a Quark-Diquark Model

Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. The resulting $Λ_b$ production rate and polarization at LEP energies are in agreement with experiment. The $Λ_c$ and $Ξ_c$ functions are also obtained. The spin independent $f_1(z)$ is compared to data. The integrated values for production rates agree with the data.

hep-ph↗

arXiv2000

A Review Essay: "Lise Meitner and the Dawn of the Nuclear Age", by Patricia Rife

The recently published book, ``Lise Meitner and the Dawn of the Nuclear Age'', by Patricia Rife (Boston: Birkhäuser, 1999) is reviewed in an essay for the lay audience. Meitner was a leading nuclear physicist at the time that the nucleus was the most exciting frontier of science. To establish her career, she had to overcome daunting prejudices against women in science and academia. Being of Jewish origin in Germany in the 1930's, she narrowly escaped certain disaster. Meitner was a crucial participant in the discovery of nuclear fission, yet did not share in the Nobel Prize that her collaborator, Otto Hahn, received in 1945. How these events came about, how they were intertwined with contemporary history and how they fit into the evolution of Meitner's social conscience and her abhorrence of war are some of the fascinating subjects discussed in the book and reviewed in this essay.

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