http://hdl.handle.net/2440/1083 2013-05-21T11:02:04Z http://hdl.handle.net/2440/77860 Title: Optically reversible photochromism in natural pink diamond Author: Byrne, K. S.; Anstie, James D.; Chapman, J. G.; Luiten, André N. 2011-12-31T13:30:00Z http://hdl.handle.net/2440/77577 Title: Non-perturbative aspects of hadron structure in QCD Author: Thomas, Anthony William 2011-12-31T13:30:00Z http://hdl.handle.net/2440/77572 Title: Effects of quark spin flip on the Collins fragmentation function in a toy model Author: Matevosyan, Hrayr; Thomas, Anthony William; Bentz, W. Abstract: The recent extension of the NJL-jet model to hadronization of transversely polarized quarks allowed the study of the Collins fragmentation function. Both favored and unfavored Collins fragmentation functions were generated, the latter purely by multiple hadron emissions, with 1/2 moments of opposite sign in the region of the light-cone momentum fraction z accessible in current experiments. Hints of such behavior has been seen in the measurements in several experiments. Also, in the transverse momentum dependent(TMD)hadron emission probabilities, modulations of up to fourth order in sine of the polar angle were observed, while the Collins effect describes just the linear modulations. A crucial part of the extended model was the calculation of the quark spin ip probability after each hadron emission in the jet. Here we study the effects of this probability on the resulting unfavored and favored Collins functions by setting it as a constant and use a toy model for the elementary single hadron emission probabilities. The results of the Monte Carlo simulations showed that preferential quark spin ip in the elementary hadron emission is needed to generate the favored and unfavored Collins functions with opposite sign 1=2 moments. For the TMD hadron emission modulations, we showed that the model quark spin ip probabilities are a partial source of the higher rode modulations, while the other source is the Collins modulation of the remnant quark from the hadron emission recoil. Description: Extent: 9 p. 2011-12-31T13:30:00Z http://hdl.handle.net/2440/77515 Title: Isospin breaking in octet baryon mass splittings Author: Horsley, Roger; Najjar, J.; Nakamura, Yoshifumi; Pleiter, Dirk; Rakow, Paul E. L.; Schierholz, Gerrit; Zanotti, James Michael; QCDSF Collaboration; UKQCD Collaboration Abstract: Using an SU(3) flavor symmetry breaking expansion in the quark mass, we determine the QCD component of the nucleon, Sigma and Xi mass splittings of the baryon octet due to up-down (and strange) quark mass differences in terms of the kaon mass splitting. Provided the average quark mass is kept constant, the expansion coefficients in our procedure can be determined from computationally cheaper simulations with mass-degenerate sea quarks and partially quenched valence quarks. Both the linear and quadratic terms in the SU(3) flavor symmetry breaking expansion are considered; it is found that the quadratic terms only change the result by a few percent, indicating that the expansion is highly convergent. 2011-12-31T13:30:00Z