The Scales of Brane Nucleation Processes

The scales associated with Brown-Teitelboim-Bousso-Polchinski processes of brane nucleation, which result in changes of the flux parameters and the number of D-branes, are discussed in the context of type IIB models with all moduli stabilized. It is argued that such processes are unlikely to be described by effective field theory.Comment: some corrections made, conclusions unchanged, references added, 10 page

N=3 Warped Compactifications

Orientifolds with three-form flux provide some of the simplest string examples of warped compactification. In this paper we show that some models of this type have the unusual feature of D=4, N=3 spacetime supersymmetry. We discuss their construction and low energy physics. Although the local form of the moduli space is fully determined by supersymmetry, to find its global form requires a careful study of the BPS spectrum.Comment: 27 pages, v2: 32pp., RevTeX4, fixed factors, slightly improved sections 3D and 4B, v3: added referenc

Moyo Vol. VII N 2

Durica, Paul. Editor\u27s Letter . 4. Spears, Amy L. As If Lipstick Was A Sign of My Declining Mind (How ChickRock Happened) . 5. Frey, Randall. Portrait of the Cartoonist as a Young Man . 6. Clements, Nina. Grease Me Up: One Woman\u27s Descent into the Depths of Pittsburgh Dinner Culture . 7. Levine, Robert. Under the Needle\u27s Point (The Healing Power of Acupuncture) . 8. Durica, Paul. The Glory that was/is Greek: Denison Three Years After the Decision . 12. Lamont, Jean. Smokin\u27 Joe Lights Up . 13. Durica, Paul. Ode on a Second Grecian Turn: An Interview with President Michele T. Myers . 14. Fisher, Dan. Lenane on the Social Scene . 19. Combe, Kirk. Intellectual Bio-Diversity: A Faculty Perspective on the Greek Residential Issue . 20. Williams, Adam. Elephants on the Floor Above and Brats in the Basement: Life on the North Quad . 22. Pfleeger, Jon. New Kid on the Block (Sigma Phi Epsilon\u27s President Speaks) . 23. Werne, Kirsten. Coffee Talk at the Bandersnatch (An Interview with Kevin Clay and Adam) . 29

String Theoretic Bounds on Lorentz-Violating Warped Compactification

We consider warped compactifications that solve the 10 dimensional supergravity equations of motion at a point, stabilize the position of a D3-brane world, and admit a warp factor that violates Lorentz invariance along the brane. This gives a string embedding of ``asymmetrically warped'' models which we use to calculate stringy (\alpha') corrections to standard model dispersion relations, paying attention to the maximum speeds for different particles. We find, from the dispersion relations, limits on gravitational Lorentz violation in these models, improving on current limits on the speed of graviton propagation, including those derived from field theoretic loops. We comment on the viability of models that use asymmetric warping for self-tuning of the brane cosmological constant.Comment: 20pg, JHEP3; v2 additional references, slight change to intro; v3. added referenc

An X-ray jet discovered by Chandra in the z=4.3 radio-selected quasar GB 1508+5714

We report the Chandra discovery of an X-ray jet associated with the redshift 4.3 radio-loud quasar GB 1508+5714. The jet X-ray emission peaks ~2 arcsec to the South-West of the quasar core. We present archival HST WFPC2 data of the quasar field which shows no optical emission at the location of the X-ray jet. We discuss possible emission mechanisms and give constraints to the magnetic field and energy densities for synchrotron radiation or for Compton scattering of the Cosmic Microwave Background radiation as the jet X-ray emission process.Comment: 5 pages, 4 figures, submitted to ApJ. Letters on Aug.13, accepted for publication in ApJ Letters on Oct.

Immigration and internal migration “flight”: A California case study

Recent analyses of 1990 census migration data have pointed up disparities in the way immigration and internal migration contributions affect an area's demographic profile. They show that there is little overlap between states with large population gains from internal migration from other parts of the United States and states with large population gains from immigration from abroad. This emerging pattern, along with the fact that immigration and internal migration select on very different demographic characteristics, could lead toward a “demographic balkanization” of the nation's population. This paper evaluates immigration-induced out-movement from California, based on an analysis of recently released migration data from the 1990 U.S. census. The results presented here suggest that California's out-migration consists of two different migration systems: first, an immigration-induced “flight” that exports lower income and less-educated Californians, primarily, to the nearby states of Washington, Oregon, Nevada and Arizona. And second, a more conventional migration exchange with the rest of the United States that involves the redistribution of better educated, higher income migrants. It is the former migration system which appears to be most responsive to the low-skilled immigration flows, while the latter should be responsive to more conventional labor market employment characteristics. This implies that, irrespective of changing economic conditions in the state, the continued immigration of low-skilled migrants will lead to more losses of native-born internal migrants to neighboring states and metropolitan areas. However, these migrant streams will not be made up of the “best and brightest” residents that characterize most conventional migration streams.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43483/1/11111_2005_Article_BF02208119.pd

Moyo Vol. VII N 1

Durica, Paul. Editor\u27s Letter . 4 Lemke, Angelica. Paxil, Effexor, and Prozac, Oh My! Is Depression Awareness Day Going Too Far? 5. Frey, Randall. Just Be: How to Make Money Without Really Doing Anything . 6. Purks, Robert. 007, Missing The Action. Dalton\u27s Bond Reconsidered . 7. Stine, Alison. Hatching A masterpiece: Jeffery Hatcher Talks of Writing, Melville, Woody Allen, and Denison . 8. Levine, Robert. Dial DU For Murder: Cinema Student Shuffles Off The Mortal Coil, and Finds it an Acquired Taste . 13. Almirall, Sarah. Dial DU For Murder: Cinema Student Shuffles Off The Mortal Coil, and Finds it an Acquired Taste, Photographs . 13. Werne, Kirsten. Back in the Day (Mom and Pop Alums Reflect on the Sixties Social Scene) . 18. Kohlbecker, Matthew. Between a Rock and a Hard Place (A Geological Excursion Into the Wilds of Canada) . 20. Lammont, Jean. Where\u27s Waldon? Comments on the Homestead . 21. Frey, Randall. Me Experimenting with Berry Beer . 25. Frey, Randall. Shoes for Mr. Jordan . 28. Porcheddu, Fred. My Late Adolescence . 30. Combe, Clayton. The Modern Guinea Pig . 31

Smeared versus localised sources in flux compactifications

We investigate whether vacuum solutions in flux compactifications that are obtained with smeared sources (orientifolds or D-branes) still survive when the sources are localised. This seems to rely on whether the solutions are BPS or not. First we consider two sets of BPS solutions that both relate to the GKP solution through T-dualities: (p+1)-dimensional solutions from spacetime-filling Op-planes with a conformally Ricci-flat internal space, and p-dimensional solutions with Op-planes that wrap a 1-cycle inside an everywhere negatively curved twisted torus. The relation between the solution with smeared orientifolds and the localised version is worked out in detail. We then demonstrate that a class of non-BPS AdS_4 solutions that exist for IASD fluxes and with smeared D3-branes (or analogously for ISD fluxes with anti-D3-branes) does not survive the localisation of the (anti) D3-branes. This casts doubts on the stringy consistency of non-BPS solutions that are obtained in the limit of smeared sources.Comment: 23 pages; v2: minor corrections, added references, version published in JHE

Moduli Stabilization from Fluxes in a Simple IIB Orientifold

We study novel type IIB compactifications on the T^6/Z_2 orientifold. This geometry arises in the T-dual description of Type I theory on T^6, and one normally introduces 16 space-filling D3-branes to cancel the RR tadpoles. Here, we cancel the RR tadpoles either partially or fully by turning on three-form flux in the compact geometry. The resulting (super)potential for moduli is calculable. We demonstrate that one can find many examples of N=1 supersymmetric vacua with greatly reduced numbers of moduli in this system. A few examples with N>1 supersymmetry or complete supersymmetry breaking are also discussed.Comment: 49 pages, harvmac big; v2, corrected some typo

The Throat as a Randall-Sundrum Model with Goldberger-Wise Stabilization

An interesting feature of type IIB flux compactifications is the natural presence of strongly warped regions or `throats'. These regions allow for a 5d Randall-Sundrum model interpretation with a large hierarchy between the UV and IR brane. We show that, in the 5d description, the flux stabilization of this hierarchy (or, equivalently, of the brane-to-brane distance) can be understood as an implementation of the Goldberger-Wise mechanism. This mechanism relies on the non-trivial bulk profile of the so-called Goldberger-Wise scalar, which in addition has fixed expectation values at the boundaries and thereby stabilizes the size of the 5d interval. The Goldberger-Wise scalar is realized microscopically by the continuously varying flux of the Neveu-Schwarz 2-form potential B_2 on the S^2 cycle in the throat. Its back-reaction on the 5d geometry leads to a significant departure from a pure AdS_5 background. We also find that, for a wide range of parameters, the universal Kaehler modulus of the 10d compactification plays the role of a UV-brane field in the equivalent 5d model. It governs the size of a large 4d curvature term localized at the UV brane. We hope that our simple 5d description of the stabilized throat will be useful in various phenomenological and cosmological applications and that refined versions of this construction will be able to account for all relevant details of the 10d model.Comment: 27 pages, 2 figures; references adde