Single-spin asymmetries in the leptoproduction of transversely polarized Λ\Lambda hyperons

We analyze single-spin asymmetries (SSAs) in the leptoproduction of transversely polarized $\Lambda$ hyperons within the collinear twist-3 formalism. We calculate both the distribution and fragmentation terms in two different gauges (lightcone and Feynman) and show that the results are identical. This is the first time that the fragmentation piece has been analyzed for transversely polarized hadron production within the collinear twist-3 framework. In lightcone gauge we use the same techniques that were employed in computing the analogous piece in $p^\uparrow p\to \pi\,X$, which has become an important part to that reaction. With this in mind, we also verify the gauge invariance of the formulas for the transverse SSA in the leptoproduction of pions.Comment: 12 pages, 1 figure, reference added, version to appear in Phys. Lett.

Longitudinal-transverse double-spin asymmetries in single-inclusive leptoproduction of hadrons

We analyze the longitudinal-transverse double-spin asymmetry in lepton-nucleon collisions where a single hadron is detected in the final state, i.e., $\vec{\ell}\,N^\uparrow \rightarrow h\,X$. This is a subleading-twist observable in collinear factorization, and we look at twist-3 effects in both the transversely polarized nucleon and the unpolarized outgoing hadron. Results are anticipated for this asymmetry from both HERMES and Jefferson Lab Hall A, and it could be measured as well at COMPASS and a future Electron-Ion Collider. We also perform a numerical study of the distribution term, which, when compared to upcoming experimental results, could allow one to learn about the "worm-gear"-type function $\tilde{g}(x)$ as well as assess the role of quark-gluon-quark correlations in the initial-state nucleon and twist-3 effects in the fragmenting unpolarized hadron.Comment: 14 pages, 7 figures, minor changes to the text, version to appear in Phys. Lett.

Twist-2 Generalized TMDs and the Spin/Orbital Structure of the Nucleon

Generalized transverse-momentum dependent parton distributions (GTMDs) encode the most general parton structure of hadrons. Here we focus on two twist-2 GTMDs which are denoted by $F_{1,4}$ and $G_{1,1}$ in parts of the literature. As already shown previously, both GTMDs have a close relation to orbital angular momentum of partons inside a hadron. However, recently even the mere existence of $F_{1,4}$ and $G_{1,1}$ has been doubted. We explain why this claim does not hold. We support our model-independent considerations by calculating the two GTMDs in the scalar diquark model and in the quark-target model, where we also explicitly check the relation to orbital angular momentum. In addition, we compute $F_{1,4}$ and $G_{1,1}$ at large transverse momentum in perturbative Quantum Chromodynamics and show that they are nonzero.Comment: 29 pages, 6 figures; two clarifications and a reference added; version to appear in Phys. Rev.

A Geometric Model for Odd Differential K-theory

Odd $K$-theory has the interesting property that it admits an infinite number of inequivalent differential refinements. In this paper we provide a bundle theoretic model for odd differential $K$-theory using the caloron correspondence and prove that this refinement is unique up to a unique natural isomorphism. We characterise the odd Chern character and its transgression form in terms of a connection and Higgs field and discuss some applications. Our model can be seen as the odd counterpart to the Simons-Sullivan construction of even differential $K$-theory. We use this model to prove a conjecture of Tradler-Wilson-Zeinalian regarding a related differential extension of odd $K$-theoryComment: 36 page

The Synthesis and Characterization of Glycol Nucleic Acids

A project was undertaken to elucidate the properties of the simplified glycol nucleic acid (GNA). GNA is novel in the fact that nucleic acid duplexes composed entirely of GNA show thermal stabilities that are superior to those of analogous DNA or RNA duplexes. Furthermore, GNA has been shown to pair with complementary sequences of RNA, but not with DNA. The first step towards understanding the thermal stabilities of GNA duplexes is the development of a straightforward synthesis of the phosphoramidites for solid phase oligonucleotide synthesis. Chapter 2 describes work towards a new set of exocyclic amino protection groups which could be removed in less time and under milder conditions than those previously reported. This new scheme results in a vastly improved synthesis of the individual phosphoramidites and allows for quicker access to the subsequent oligonucleotides. With easy access to GNA oligonucleotides in hand, the next goal was to use spectroscopy to compare the duplex formation properties with that of DNA as outlined in Chapter 3. These studies pointed to the preorganization of the single strands and increased stacking interactions as the main factors that increase the stability of GNA duplexes. Although the studies in Chapter 3 present a basic understanding of GNA duplex formation, it did not provide the direct structural insight that was desired. Chapter 4 presents the synthesis and pairing properties of three artificial metal-mediated base pairs in GNA duplexes; one of which was used as a handle in an 8-mer duplex for phasing the crystallographic data, thereby providing the initial structural insight that was desired. Uncertain as to the extent by which the artificial metal-mediated base pair perturbs the overall structure of GNA, several other structures of GNA duplexes containing exclusively Watson-Crick base pairs are presented in Chapter 5. The most impressive structure of a 6-mer GNA duplex displays many common structural features to that of the 8-mer duplex containing artificial base pairs. Overall this research has provided insight into the exceptional duplex formation properties of glycol nucleic acids and should provide the basis for future research on the application of GNA duplexes for various biological or technical purposes