Charge Stripe in an Antiferromagnet: 1d Band of Composite Excitations

With the help of analytical and numerical studies of the $t$-$J_z$ model we argue that the charge stripe in an antiferromagnetic insulator should be understood as a system of holon-spin-polaron excitations condensed at the self-induced antiphase domain wall. The structure of such a charge excitation is studied in detail with numerical and analytical results for various quantities being in a very close agreement. An analytical picture of these excitations occupying an effective 1D stripe band is also in a very good accord with numerical data. The emerging concept advocates the primary role of the kinetic energy in favoring the stripe as a ground state. A comparative analysis suggests the effect of pairing and collective meandering on the energetics of the stripe formation to be secondary.Comment: 5 pages, 3 figures, proceedings of SCES'01 conference, Ann Arbor, 2001, to be published in Physica

[Review of] Fran Leeper Buss, La Partera: Story of a Midwife

La Partera is the story of Jesusita Aragén, one of the last traditional midwives of northeastern New Mexico, as written from recorded interviews between the author and Jesusita. Before telling Jesusita\u27s account of her own life, the author introduces the reader geographically, historically, and culturally to the area of San Miguel County and its main city of Las Vegas. Buss clearly shows her love and understanding of this region where she and her husband served as United Church of Christ ministers in 1975. She writes, ”the weather is dominated by striking turquoise skies and a brilliant, penetrating sun” (p. 2) and describes the area as a largely rural county which straddles the forested mountains, the foothills and the plains.” (p. 4) She states that the majority of the people in west Las Vegas are Hispanic New Mexican, touching on the Hispanic settlement, religious customs, and health care practices of the region. At the turn of the century, curanderas, médicas, and parteras, a female network, delivered health care to the area until the early 1930s, when Anglo medical personnel, again mostly women, began to take over these services

The Zeldovich approximation

This year marks the 100th anniversary of the birth of Yakov Zel'dovich. Amongst his many legacies is the Zel'dovich approximation for the growth of large-scale structure, which remains one of the most successful and insightful analytic models of structure formation. We use the Zel'dovich approximation to compute the two-point function of the matter and biased tracers, and compare to the results of N-body simulations and other Lagrangian perturbation theories. We show that Lagrangian perturbation theories converge well and that the Zel'dovich approximation provides a good fit to the N-body results except for the quadrupole moment of the halo correlation function. We extend the calculation of halo bias to 3rd order and also consider non-local biasing schemes, none of which remove the discrepancy. We argue that a part of the discrepancy owes to an incorrect prediction of inter-halo velocity correlations. We use the Zel'dovich approximation to compute the ingredients of the Gaussian streaming model and show that this hybrid method provides a good fit to clustering of halos in redshift space down to scales of tens of Mpc.Comment: 11 pages, 7 figures. Minor modifications to match version accepted by MNRAS. Erratum added to shear equations in Appendix, no conclusions change

Comment on ``Stripes and the t-J Model''

This is a comment being submitted to Physical Review Letters on a recent letter by Hellberg and Manousakis on stripes in the t-J model.Comment: One reference correcte