Searches for CP violation in two-body charm decays

The LHCb experiment recorded data corresponding to an integrated luminosity of 3.0 $fb^{-1}$ during its first run of data taking. These data yield the largest samples of charmed hadrons in the world and are used to search for CP violation in the $D^0$ system. Among the many measurements performed at LHCb, a measurement of the direct CP asymmetry in $D^0 \rightarrow K_S^0 K_S^0$ decays is presented and is found to be $A_{CP}(D^0 \rightarrow K_S^0 K_S^0) = (-2.9 \pm 5.2 \pm 2.2)\, \%,$ where the first uncertainty is statistical and the second systematic. This represents a significant improvement in precision over the previous measurement of this parameter. Measurements of the parameter $A^\Gamma$, defined as the CP asymmetry of the $D^0$ effective lifetime when decaying to a CP eigenstate, are also presented. Using semi-leptonic b-hadron decays to tag the flavour of the $D^0$ meson at production with the $K^+K^-$ and $\pi^+\pi^-$ final states yields $A^\Gamma(K^+K^-) = (-0.134 \pm 0.077^{+0.026}_{-0.034})\, \%,$ $A^\Gamma(\pi^+\pi^-) = (-0.092 \pm 0.145^{+0.025}_{-0.033})\, \%.$ Thus no evidence of direct or indirect CP violation in the $D^0$ system is found, though it is tightly constrained.Comment: Proceedings for The European Physical Society Conference on High Energy Physics, 22-29 July 2015, Vienna, Austria. On behalf of the LHCb collaboratio

Charm: Mixing, CP Violation and Rare Decays at LHCb

Recent results on mixing, CP violation and rare decays in charm physics from the LHCb experiment are presented. Study of ''wrong-sign'' $D^{0} \rightarrow K^+ \pi^-$ decays provides the highest precision measurements to date of the mixing parameters $x^{\prime 2}$ and $y^{\prime}$, and of CP violation in this decay mode. Direct and indirect CP violation in the $D^0$ system are probed to a sensitivity of around $10^{-3}$ using $D^0 \rightarrow K^+K^-$ and $D^0 \rightarrow \pi^+\pi^-$ decays and found to be consistent with zero. Searches for the rare decays $D^+_{(s)} \rightarrow \pi^+\mu^+\mu^-$, $D^+_{(s)} \rightarrow \pi^-\mu^+\mu^+$ and $D^0 \rightarrow \mu^+\mu^-$ find no evidence of signal, but set the best limits on branching fractions to date. Thus, despite many excellent results in charm physics from LHCb, no evidence for physics beyond the Standard Model is found.Comment: Proceedings for PhiPsi 2013 conference. 6 pages, 3 figure

Finite energy coordinates and vector analysis on fractals

We consider (locally) energy finite coordinates associated with a strongly local regular Dirichlet form on a metric measure space. We give coordinate formulas for substitutes of tangent spaces, for gradient and divergence operators and for the infinitesimal generator. As examples we discuss Euclidean spaces, Riemannian local charts, domains on the Heisenberg group and the measurable Riemannian geometry on the Sierpinski gasket

Time is wasting: con/sequence and s/pace in the Saw series

Horror film sequels have not received as much serious critical attention as they deserve this is especially true of the Saw franchise, which has suffered a general dismissal under the derogatory banner Torture Porn. In this article I use detailed textual analysis of the Saw series to expound how film sequels employ and complicate expected temporal and spatial relations in particular, I investigate how the Saw sequels tie space and time into their narrative, methodological and moral sensibilities. Far from being a gimmick or a means of ensuring loyalty to the franchise (one has to be familiar with the events of previous episodes to ascertain what is happening), it is my contention that the Saw cycle directly requests that we examine the nature of space and time, in terms of both cinematic technique and our lived, off-screen temporal/spatial orientations

Beauville surfaces and finite simple groups

A Beauville surface is a rigid complex surface of the form (C1 x C2)/G, where C1 and C2 are non-singular, projective, higher genus curves, and G is a finite group acting freely on the product. Bauer, Catanese, and Grunewald conjectured that every finite simple group G, with the exception of A5, gives rise to such a surface. We prove that this is so for almost all finite simple groups (i.e., with at most finitely many exceptions). The proof makes use of the structure theory of finite simple groups, probability theory, and character estimates.Comment: 20 page