LHCb status and charm physics program

LHCb is a dedicated flavor physics experiment that will observe the 14 TeV proton-proton collisions at CERN's Large Hadron Collider (LHC). Construction of the LHCb detector is near completion, commissioning of the detector is well underway, and LHCb will be fully operational and ready to take data in advance of the projected May 2008 turn-on date for the LHC. The LHCb software trigger will feature a dedicated channel for events containing D* mesons that will dramatically enhance the statistical reach of LHCb in many charm physics measurements. The LHCb charm physics program is initially focused on mixing and CP violation measurements in two body decay modes of D0. A much broader program is possible and will be explored as manpower allows. We intend to use both promptly produced charm and secondary charm from B meson decays in measurements. Initial studies have focused on using secondary D*+ mesons for mixing measurements in two body decays. Preliminary Monte Carlo studies indicate that LHCb may obtain a statistical precision of \sigma(x'^2) = +/- 0.064 x 10^{-3} (stat) and \sigma(y') = +/- 0.87 x 10^{-3} (stat) from a time dependent mixing analysis of wrong sign two body D0 --> pi- K+ decays and a statistical precision of \sigma(y_{CP}) = +/- 0.5 x 10^{-3} (stat) from a ratio of the lifetimes of D0 decays to the final states K- K+ and K- pi+ in 10 fb^{-1} of data.Comment: To be published in the proceedings of CHARM07, Ithaca, NY, August 2007, eConf C070805. Updated to respect collaboration authorship convention

Dense Quarks, and the Fermion Sign Problem, in a SU(N) Matrix Model

We study the effect of dense quarks in a SU(N) matrix model of deconfinement. For three or more colors, the quark contribution to the loop potential is complex. After adding the charge conjugate loop, the measure of the matrix integral is real, but not positive definite. In a matrix model, quarks act like a background Z(N) field; at nonzero density, the background field also has an imaginary part, proportional to the imaginary part of the loop. Consequently, while the expectation values of the loop and its complex conjugate are both real, they are not equal. These results suggest a possible approach to the fermion sign problem in lattice QCD.Comment: 9 pages, 3 figure

Degravitation, Inflation and the Cosmological Constant as an Afterglow

In this report, we adopt the phenomenological approach of taking the degravitation paradigm seriously as a consistent modification of gravity in the IR, and investigate its consequences for various cosmological situations. We motivate degravitation-- where Netwon's constant is promoted to a scale dependent filter function-- as arising from either a small (resonant) mass for the graviton, or as an effect in semi-classical gravity. After addressing how the Bianchi identities are to be satisfied in such a set up, we turn our attention towards the cosmological consequences of degravitation. By considering the example filter function corresponding to a resonantly massive graviton (with a filter scale larger than the present horizon scale), we show that slow roll inflation, hybrid inflation and old inflation remain quantitatively unchanged. We also find that the degravitation mechanism inherits a memory of past energy densities in the present epoch in such a way that is likely significant for present cosmological evolution. For example, if the universe underwent inflation in the past due to it having tunneled out of some false vacuum, we find that degravitation implies a remnant `afterglow' cosmological constant, whose scale immediately afterwards is parametrically suppressed by the filter scale ($L$) in Planck units $\Lambda \sim l^2_{pl}/L^2$. We discuss circumstances through which this scenario reasonably yields the presently observed value for $\Lambda \sim O(10^{-120})$. We also find that in a universe still currently trapped in some false vacuum state, resonance graviton models of degravitation only degravitate initially Planck or GUT scale energy densities down to the presently observed value over timescales comparable to the filter scale.Comment: To appear in JCAP; sections discussing degravitation as a semi-classical effect and the modified Bianchi identities adde

Dressing the Giant Magnon II

We extend our earlier work by demonstrating how to construct classical string solutions describing arbitrary superpositions of scattering and bound states of dyonic giant magnons on S^5 using the dressing method for the SU(4)/Sp(2) coset model. We present a particular scattering solution which generalizes solutions found in hep-th/0607009 and hep-th/0607044 to the case of arbitrary magnon momenta. We compute the classical time delay for the scattering of two dyonic magnons carrying angular momenta with arbitrary relative orientation on the S^5.Comment: 13 pages, harvma

Shared mission operations concept

Historically, new JPL flight projects have developed a Mission Operations System (MOS) as unique as their spacecraft, and have utilized a mission-dedicated staff to monitor and control the spacecraft through the MOS. NASA budgetary pressures to reduce mission operations costs have led to the development and reliance on multimission ground system capabilities. The use of these multimission capabilities has not eliminated an ongoing requirement for a nucleus of personnel familiar with a given spacecraft and its mission to perform mission-dedicated operations. The high cost of skilled personnel required to support projects with diverse mission objectives has the potential for significant reduction through shared mission operations among mission-compatible projects. Shared mission operations are feasible if: (1) the missions do not conflict with one another in terms of peak activity periods, (2) a unique MOS is not required, and (3) there is sufficient similarity in the mission profiles so that greatly different skills would not be required to support each mission. This paper will further develop this shared mission operations concept. We will illustrate how a Discovery-class mission would enter a 'partner' relationship with the Voyager Project, and can minimize MOS development and operations costs by early and careful consideration of mission operations requirements

Orientifolded Locally AdS3 Geometries

Continuing the analysis of [arXiv:1003.4089[hep-th]], we classify all locally AdS3 stationary axi-symmetric unorientable solutions to AdS3 Einstein gravity and show that they are obtained by applying certain orientifold projection on AdS3, BTZ or AdS3 self-dual orbifold, respectively O-AdS3, O-BTZ and O-SDO geometries. Depending on the orientifold fixed surface, the O-surface, which is either a space-like 2D plane or cylinder, or a light-like 2D plane or cylinder one can distinguish four distinct cases. For the space-like orientifold plane or cylinder cases these geometries solve AdS3 Einstein equations and are hence locally AdS3 everywhere except at the O-surface, where there is a delta-function source. For the light-like cases the geometry is a solution to Einstein equations even at the O-surface. We discuss the causal structure for static, extremal and general rotating O-BTZ and O-SDO cases as well as the geodesic motion on these geometries. We also discuss orientifolding Poincare patch AdS3 and AdS2 geometries as a way to geodesic completion of these spaces and comment on the 2D CFT dual to the O-geometries.Comment: 26 page, 4 .eps figure

Tachyons in de Sitter space and analytical continuation from dS/CFT to AdS/CFT

We discuss analytic continuation from d-dimensional Lorentzian de Sitter (dS$_d$) to d-dimensional Lorentzian anti-de Sitter (AdS$_{d}$) spacetime. We show that AdS$_{d}$, with opposite signature of the metric, can be obtained as analytic continuation of a portion of dS$_d$. This implies that the dynamics of (positive square-mass) scalar particles in AdS$_{d}$ can be obtained from the dynamics of tachyons in dS$_d$. We discuss this correspondence both at the level of the solution of the field equations and of the Green functions. The AdS/CFT duality is obtained as analytic continuation of the dS/CFT duality.Comment: 17 pages, 1 figure, JHEP styl

Quantum Entropy Function from AdS(2)/CFT(1) Correspondence

We review and extend recent attempts to find a precise relation between extremal black hole entropy and degeneracy of microstates using AdS_2/CFT_1 correspondence. Our analysis leads to a specific relation between degeneracy of black hole microstates and an appropriately defined partition function of string theory on the near horizon geometry, -- named the quantum entropy function. In the classical limit this reduces to the usual relation between statistical entropy and Wald entropy.Comment: LaTeX file, 27 pages, A modified and extended version of the talk given at Strings 200

PP-wave and Non-supersymmetric Gauge Theory

We extend the pp-wave correspondence to a non supersymmetric example. The model is the type 0B string theory on the pp-wave R-R background. We explicitly solve the model and give the spectrum of physical states. The field theory counterpart is given by a sector of the large N SU(N) x SU(N) CFT living on a stack of N electric and N magnetic D3-branes. The relevant effective coupling constant is g_{eff}=g_sN/J^2. The string theory has a tachyon in the spectrum, whose light-cone energy can be exactly computed as a function of g_{eff}. We argue that the perturbative analysis in g_{eff} in the dual gauge theory is reliable, with corrections of non perturbative type. We find a precise state/operator map, showing that the first perturbative corrections to the anomalous dimensions of the operators have the behavior expected from the string analysis.Comment: 19 pages. Revised versio

Giant Magnons and Singular Curves

We obtain the giant magnon of Hofman-Maldacena and its dyonic generalisation on R x S^3 < AdS_5 x S^5 from the general elliptic finite-gap solution by degenerating its elliptic spectral curve into a singular curve. This alternate description of giant magnons as finite-gap solutions associated to singular curves is related through a symplectic transformation to their already established description in terms of condensate cuts developed in hep-th/0606145.Comment: 34 pages, 17 figures, minor change in abstrac