Status of the Fermilab Muon (g-2) Experiment

The New Muon $(g-2)$ Collaboration at Fermilab has proposed to measure the anomalous magnetic moment of the muon, $a_\mu$, a factor of four better than was done in E821 at the Brookhaven AGS, which obtained $a_\mu = [116 592 089 (63)] \times 10^{-11}$ $\pm 0.54$ ppm. The last digit of $a_{\mu}$ is changed from the published value owing to a new value of the ratio of the muon-to-proton magnetic moment that has become available. At present there appears to be a difference between the Standard-Model value and the measured value, at the $\simeq 3$ standard deviation level when electron-positron annihilation data are used to determine the lowest-order hadronic piece of the Standard Model contribution. The improved experiment, along with further advances in the determination of the hadronic contribution, should clarify this difference. Because of its ability to constrain the interpretation of discoveries made at the LHC, the improved measurement will be of significant value, whatever discoveries may come from the LHC.Comment: Proceedings of the PhiPsi09, Oct. 13-16, 2009, Beijing, China, 4 pages 2 figures. Version 2 includes Fermilab report number, minor corrections and one additional referenc

Recent progress on isospin breaking corrections and their impact on the muon g-2 value

We describe some recent results on isospin breaking corrections which are of relevance for predictions of the leading order hadronic contribution to the muon anomalous magnetic moment (amuhadLO) when using tau lepton data. When these corrections are applied to the new combined data on the pi^+pi^0 spectral function, the prediction for amuhadLO based on tau lepton data gets closer to the one obtained using e^+e^- data.Comment: 6 pages, 3 figures, Proceedings of the PhiPsi09 Workshop, Oct. 13-16, 2009, Beijing, China. Some typos corrected, and the FSR correction used in a previous work is added to Table

Electromagnetic form factors of charged and neutral kaons in an extended vector-meson-dominance model

A model is developed for electromagnetic form factors of the charged and neutral K-mesons. The formalism is based on ChPT Lagrangians with vector mesons. The form factors, calculated without fitting parameters, are in a good agreement with experiment for space-like and time-like photon momenta. Contribution of the two-kaon channels to the muon anomalous magnetic moment a_\mu is calculated.Comment: 23 pages, 11 figures, accepted for publication in Eur. Phys. J.

Near Elimination of Ventricular Pacing in SafeR Mode Compared to DDD Modes: A Randomized Study of 422 Patients

Aims:SafeR performance versus DDD/automatic mode conversion (DDD/AMC) and DDD with a 250-ms atrioventricular (AV) delay (DDD/LD) modes was assessed toward ventricular pacing (Vp) reduction. Methods:After a 1-month run-in phase, recipients of dual-chamber pacemakers without persistent AV block and persistent atrial fibrillation (AF) were randomly assigned to SafeR, DDD/AMC, or DDD/LD in a 1:1:1 design. The main endpoint was the percentage of Vp (%Vp) at 2 months and 1 year after randomization, ascertained from device memories. Secondary endpoints include %Vp at 1 year according to pacing indication and 1-year AF incidence based on automatic mode switch device stored episodes. Results:Among 422 randomized patients (73.2 ± 10.6 years, 50% men, sinus node dysfunction 47.4%, paroxysmal AV block 30.3%, bradycardia-tachycardia syndrome 21.8%), 141 were assigned to SafeR versus 146 to DDD/AMC and 135 to DDD/LD modes. Mean %Vp at 2 months was 3.4 ± 12.6% in SafeR versus 33.6 ± 34.7% and 14.0 ± 26.0% in DDD/AMC and DDD/LD modes, respectively (P < 0.0001 for both). At 1 year, mean %Vp in SafeR was 4.5 ± 15.3% versus 37.9 ± 34.4% and 16.7 ± 28.0% in DDD/AMC and DDD/LD modes, respectively (P < 0.0001 for both). The proportion of patients in whom Vp was completely eliminated was significantly higher in SafeR (69%) versus DDD/AMC (15%) and DDD/LD (45%) modes (P < 0.0001 for both), regardless of pacing indication. The absolute risk of developing permanent AF or of remaining in AF for >30% of the time was 5.4% lower in SafeR than in the DDD pacing group (ns). Conclusions:In this selected patient population, SafeR markedly suppressed unnecessary Vp compared with DDD modes. PACE 2012; 35:392–402

Hadronic light-by-light scattering contribution to the muon g-2

We review recent developments concerning the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon. We first discuss why fully off-shell hadronic form factors should be used for the evaluation of this contribution to the g-2. We then reevaluate the numerically dominant pion-exchange contribution in the framework of large-N_C QCD, using an off-shell pion-photon-photon form factor which fulfills all QCD short-distance constraints, in particular, a new short-distance constraint on the off-shell form factor at the external vertex in g-2, which relates the form factor to the quark condensate magnetic susceptibility in QCD. Combined with available evaluations of the other contributions to hadronic light-by-light scattering this leads to the new result a_{\mu}(LbyL; had) = (116 \pm 40) x 10^{-11}, with a conservative error estimate in view of the many still unsolved problems. Some potential ways for further improvements are briefly discussed as well. For the electron we obtain the new estimate a_{e}(LbyL; had) = (3.9 \pm 1.3) x 10^{-14}.Comment: 6 pages, 1 figure, to be published in the proceedings of the PhiPsi09 workshop, Oct. 13-16, 2009, Beijing, Chin

New results on the hadronic vacuum polarization to the muon g-2

Results on the lowest-order hadronic vacuum polarization contribution to the muon magnetic anomaly are presented. They are based on the latest published experimental data used as input to the dispersion integral. Thus recent results on tau to nutau pi pi0 decays from Belle and on e+ e- annihilation to pi+ pi- from BABAR and KLOE are included. The new data, together with improved isospin-breaking corrections for tau decays, result into a much better consistency among the different results. A discrepancy between the Standard Model prediction and the direct g-2 measurement is found at the level of 3 sigma.Comment: proceedings of the PhiPsi09 conference, Oct. 13-16, 2009, Beijing, Chin

Quenched BKB_K-parameter with the Wilson and Clover actions at β=6.0\beta = 6.0

We present results for the Kaon $B$ parameter from a sample of $200$ configurations using the Wilson action and $460$ configurations using the Clover action, on a $18^3 \times 64$ lattice at $\beta=6.0$. A slight improvement of the chiral behaviour of $B_K$ is observed due to the Clover action. We have also compared the results for $B_K$ obtained from two different procedures for the boosting of the coupling constant $g$. We observe a strong dependence of $B_K$ on the prescription adopted for $g$ in the Wilson case, contrary to the results of the Clover case which are almost unaffected by the choice of $g$. Combining some recently obtained non perturbative estimates for the renormalisation constants with our Clover matrix element, we observe a significant improvement in the chiral behaviour of $B_K$.Comment: 3 pages, Latex, Postscript file with figures available at ftp://hpteo.roma1.infn.it/pub/preprints/lat94/donini ; to appear in Lattice '94, Nucl. Phys. (Proc.Suppl.

Morphology of two dimensional fracture surface

We consider the morphology of two dimensional cracks observed in experimental results obtained from paper samples and compare these results with the numerical simulations of the random fuse model (RFM). We demonstrate that the data obey multiscaling at small scales but cross over to self-affine scaling at larger scales. Next, we show that the roughness exponent of the random fuse model is recovered by a simpler model that produces a connected crack, while a directed crack yields a different result, close to a random walk. We discuss the multiscaling behavior of all these models.Comment: slightly revise

New 4-(N-cinnamoylbutyl)aminoacridines as potential multi-stage antiplasmodial leads

A novel family of 4-aminoacridine derivatives was obtained by linking this heteroaromatic core to different trans-cinnamic acids. The 4-(N-cinnamoylbutyl)aminoacridines obtained exhibited in vitro activity in the low- or sub-micromolar range against (i) hepatic stages of Plasmodium berghei, (ii) erythrocytic forms of Plasmodium falciparum, and (iii) early and mature gametocytes of Plasmodium falciparum. The most active compound, having a meta-fluorocinnamoyl group linked to the acridine core, was 20- and 120-fold more potent, respectively, against the hepatic and gametocyte stages of Plasmodium infection than the reference drug, primaquine. Moreover, no cytotoxicity towards mammalian and red blood cells at the concentrations tested was observed for any of the compounds under investigation. These novel conjugates represent promising leads for the development of new multi-target antiplasmodials.Copyright © 2023 The Authors. Published by Elsevier Masson SAS.. All rights reserved