On measuring the leptonic forward-backward asymmetry at the Tevatron and recent results from CDF

The larger-than-expected forward-backward asymmetry of the topquark pairs produced in proton-antiproton collisions is suggestive of new physics. The forward-backward asymmetry of the charged leptons from the cascade decay of top-quark pairs serve as an complementary test for evidence for or against new physics. We provide a detailed study of the methodology used to measure the leptonic asymmetry at CDF, and measure the leptonic asymmetry in leptonic top quark pair decays, as well as the CDF combination of the leptonic asymmetry. The CDF leptonic asymmetry combination shows a 2 standard-deviation larger value than the next–to–leading-order standard model expectation

Forward–Backward Asymmetry of Top Quark Pair Production at the Fermilab Tevatron

This dissertation presents the final measurements of the forward-backward asymmetry (AFB) of top quark-antiquark pair events (tt) at the Collider Detector at Fermilab (CDF) experiment. The tt events are produced in proton-anti-proton collisions with a center of mass energy of 1:96 TeV during the Run II of the Fermilab Tevatron. The measurements are performed with the full CDF Run II data (9:1 fb^-1) in the final state that contain two charged leptons (electrons or muons, the dilepton final state), and are designed to confirm or deny the evidence-level excess in the AFB measurements in the final state with a single lepton and hadronic jets (lepton+jets final state) as well as the excess in the preliminary measurements in the dilepton final state with the first half of the CDF Run II data. New measurements include the leptonic AFB (A^l FB), the lepton-pair AFB (A^ll FB) and the reconstructed top AFB (A^tt FB). Each are combined with the previous results from the lepton+jets final state measured at the CDF experiment. The inclusive A^l FB, A^ll FB, and A^tt FB measured in the dilepton final state are 0:072 ± 0:060, 0:076 ± 0:081, and 0:12 ± 0:13, to be compared with the Standard Model (SM) predictions of 0:038 ± 0:003, 0:048 ± 0:004, and 0:010 ± 0:006, respectively. The CDF combination of A^l FB and A^tt FB are 0:090^+0:028 -0:026, and 0:160 ± 0:045, respectively. The overall results are consistent with the SM predictions

On the Forward-Backward Asymmetry of Leptonic Decays of ttˉt\bar{t} at the Fermilab Tevatron

We report on a study of the measurement techniques used to determine the leptonic forward-backward asymmetry of top anti-top quark pairs in Tevatron experiments with a proton anti-proton initial state. Recently it was shown that a fit of the differential asymmetry as a function of $q_{l}\eta_{l}$ (where $q_{l}$ is the charge of the lepton from the cascade decay of the top quarks and $\eta_{l}$ is the final pseudorapidity of the lepton in the detector frame) to a hyperbolic tangent function can be used to extrapolate to the full leptonic asymmetry. We find this empirical method to well reproduce the results from current experiments, and present arguments as to why this is the case. We also introduce two more models, based on Gaussian functions, that better model the $q_{l}\eta_{l}$ distribution. With our better understanding, we find that the asymmetry is mainly determined by the shift of the mean of the $q_{l}\eta_{l}$ distribution, the main contribution to the inclusive asymmetry comes from the region around $|q_{l}\eta_{l}| = 1$, and the extrapolation from the detector-covered region to the inclusive asymmetry is stable via a multiplicative scale factor, giving us confidence in the previously reported experimental results.Comment: 26 pages, 12 figure

Novel Smart N95 Filtering Facepiece Respirator with Real-time Adaptive Fit Functionality and Wireless Humidity Monitoring for Enhanced Wearable Comfort

The widespread emergence of the COVID-19 pandemic has transformed our lifestyle, and facial respirators have become an essential part of daily life. Nevertheless, the current respirators possess several limitations such as poor respirator fit because they are incapable of covering diverse human facial sizes and shapes, potentially diminishing the effect of wearing respirators. In addition, the current facial respirators do not inform the user of the air quality within the smart facepiece respirator in case of continuous long-term use. Here, we demonstrate the novel smart N-95 filtering facepiece respirator that incorporates the humidity sensor and pressure sensory feedback-enabled self-fit adjusting functionality for the effective performance of the facial respirator to prevent the transmission of airborne pathogens. The laser-induced graphene (LIG) constitutes the humidity sensor, and the pressure sensor array based on the dielectric elastomeric sponge monitors the respirator contact on the face of the user, providing the sensory information for a closed-loop feedback mechanism. As a result of the self-fit adjusting mode along with elastomeric lining, the fit factor is increased by 3.20 and 5 times at average and maximum respectively. We expect that the experimental proof-of-concept of this work will offer viable solutions to the current commercial respirators to address the limitations.Comment: 20 pages, 5 figures, 1 table, submitted for possible publicatio

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference

A Stress Induced Source of Phonon Bursts and Quasiparticle Poisoning

The performance of superconducting qubits is degraded by a poorly characterized set of energy sources breaking the Cooper pairs responsible for superconductivity, creating a condition often called "quasiparticle poisoning." Recently, a superconductor with one of the lowest average quasiparticle densities ever measured exhibited quasiparticles primarily produced in bursts which decreased in rate with time after cooldown. Similarly, several cryogenic calorimeters used to search for dark matter have also observed an unknown source of low-energy phonon bursts that decrease in rate with time after cooldown. Here, we show that a silicon crystal glued to its holder exhibits a rate of low-energy phonon events that is more than two orders of magnitude larger than in a functionally identical crystal suspended from its holder in a low-stress state. The excess phonon event rate in the glued crystal decreases with time since cooldown, consistent with a source of phonon bursts which contributes to quasiparticle poisoning in quantum circuits and the low-energy events observed in cryogenic calorimeters. We argue that relaxation of thermally induced stress between the glue and crystal is the source of these events, and conclude that stress relaxation contributes to quasiparticle poisoning in superconducting qubits and the athermal phonon background in a broad class of rare-event searches.Comment: 13 pages, 6 figures. W. A. Page and R. K. Romani contributed equally to this work. Correspondence should be addressed to R. K. Roman