110567078
ASIC developments for high speed serial data transmission in particle physics experiments
Abstract We report R&D results on two integrated circuit designs: a 5 Gbps 16:1 serializer and a 5 GHz LC phase-locked-loop (PLL). The prototypes were fabricated with a commercial thin-film silicon-on-sapphire 0.25 μm CMOS technology. Both the serializer and the PLL have been evaluated to meet design goals and tested against operation conditions in the environment of a particle physics detector front-end for the proposed HL-LHC upgrade.
17176468
Status report on the LOC ASIC
Based on a commercially available 0.25 μm Silicon on Sapphire CMOS technology, we are developing the LOC ASIC for high speed serial data transmission in the front-end electronics systems of the ATLAS upgrade for the SLHC 1 . Evaluation of this technology for applications in the SLHC, based on a dedicated test chip, has been performed with irradiation tests in gamma (Co-60) and in 230 MeV proton beams. Test results indicate that this may be a candidate technology of ASIC developments for the SLHC. More thorough evaluation tests will be carried out under another R&D program supported through the Advanced Detector Research (ADR) from the Department of Energy. Characterization tests on the first prototype serializer, LOC1, have been carried out in lab. Based on the lessons learned from this chip, we propose a new architecture design of the second prototype, LOC2, aiming for a serial data rate in the range of 5 Gbps. Simulation on key components of LOC2 are being carried out and the results we have so far are presented in this note. LOC2 is scheduled to be submitted for fabrication in the first half of 2009.
6496614
Response of a 0.25 μm thin-film silicon-on-sapphire CMOS technology to total ionizing dose
The radiation response of a 0.25 μm silicon-on-sapphire CMOS technology is characterized at the transistor and circuit levels utilizing both standard and enclosed layout devices. The threshold-voltage shift is less than 170 mV and the leakage-current increase is less than 1 nA for individual standard-layout nMOSFET and pMOSFET devices at a total dose of 100 krad(SiO2). The increase in power supply current at the circuit level was less than 5%, consistent with the small change in off-state transistor leakage current. The technology exhibits good characteristics for use in the electronics of the ATLAS experiment at the Large Hadron Collider.
119231771
Multiple b -jets reveal top superpartners and the 125 GeV Higgs
We demonstrate that in supersymmetry (SUSY) with relatively light top superpartners, h -> bb can be a very promising channel to discover the SM-like Higgs resonance at the Large Hadron Collider (LHC), although in general contexts it is thought to be challenging because of its huge QCD background. In this scenario, the SM-like Higgs boson is mainly produced via cascade decays initiated by pair-produced stop or sbottom squarks. The good sensitivity to h -> bb owes a great deal to the application of multiple (>= 4) b-jet tagging in removing the QCD background, and color-flow variables for reconstructing the Higgs resonance. We show in two benchmark points that a SM-like Higgs resonance can be discovered at the 14 TeV LHC (with a signal-to-background ratio as high as 0.35), with ~< 40/fb of data. Potentially, this strategy can be also applied to non-SUSY theories with cascade decays of top partners for the SM-like Higgs search, such as little Higgs, composite Higgs, and Randall-Sundrum models.
14074616
Classification of supersymmetric flux vacua in M-theory
Abstract We present a comprehensive classification of supersymmetric vacua of M-theory compactification on seven-dimensional manifolds with general four-form fluxes. We analyze the cases where the resulting four-dimensional vacua have N = 1 , 2 , 3 , 4 supersymmetry and the internal space allows for SU ( 2 ) , SU ( 3 ) or G 2 structures. In particular, we find for N = 2 supersymmetry, that the external space–time is Minkowski and the base manifold of the internal space is conformally Kahler for SU ( 2 ) structures, while for SU ( 3 ) structures the internal space has to be Einstein–Sasaki and no internal fluxes are allowed. Moreover, we provide a new vacuum with N = 1 supersymmetry and SU ( 3 ) structure, where all fluxes are non-zero and the first order differential equations are solved.
119209516
Polarized view of the top asymmetry
Recent experimental results from the CDF collaboration which study the top forward-backward asymmetry have strengthened the case that new physics is playing a role in $t\overline{t}$ production. Here, we propose a set of measurements, built from the charged lepton kinematics in semileptonic and fully leptonic $t\overline{t}$ events, designed to further probe the underlying causes of this asymmetry both at the Tevatron and at the LHC. Using a set of conservative reference models, we find that measurements of the charged lepton asymmetry, top polarization, and $t\overline{t}$ spin correlation can establish the existence of new physics and distinguish between competing models both at the Tevatron and the LHC. At the Tevatron, discrimination between models is possible at the $3\ensuremath{\sigma}$ level. At the LHC, we demonstrate that a top forward-backward asymmetry can be established at $\ensuremath{\gtrsim}3\ensuremath{\sigma}$ in the first $\ensuremath{\sim}5\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data and show how competing explanations can be further disentangled.
33634938
Standardlike models as type IIB flux vacua
We construct new semirealistic type IIB flux vacua on ${Z}_{2}\ifmmode\times\else\texttimes\fi{}{Z}_{2}$ orientifolds with three- and four-standard model families and up to three units of quantized flux. The open string sector is comprised of magnetized D-branes and is T-dual to supersymmetric intersecting D6-brane constructions. The standard model sector contains magnetized D9-branes with negative D3-brane charge contribution. There are large classes of such models and we present explicit constructions for representative ones. In addition to models with one and two units of quantized flux, we also construct the first three- and four-family standard-like models with supersymmetric fluxes, i.e. comprising three units of quantized flux. Supergravity fluxes are due to the self-dual Neveu-Schwarz-Neveu-Schwarz and Ramond-Ramond three-form field strength and they fix the toroidal complex structure moduli and the dilaton. The supersymmetry conditions for the D-brane sector fix in some models all three toroidal K\"ahler moduli. We also provide examples where toroidal K\"ahler moduli are fixed by strong gauge dynamics on the ``hidden sector'' D7-brane. Most of the models possess Higgs doublet pairs with Yukawa couplings that can generate masses for quarks and leptons. The models have (mainly right-) chiral exotics.
44596378
Unraveling the physics behind modified Higgs couplings: LHC versus a Higgs factory
Strongly modified $h\ensuremath{\gamma}\ensuremath{\gamma}$ and $hgg$ couplings indicate new electroweak and color mediators, respectively, with a light mass and a significant coupling to the Higgs boson. We point out the Higgs boson could have a significant decay width into the mediators. This represents one new class of exotic Higgs decay possibilities: off-shell exotic Higgs decays. We then propose uncovering the hidden new physics through such exotic decays. A great advantage of this strategy is that we can directly probe the couplings between the Higgs boson and the mediators, which is hard to achieve by using other methods. Focusing on the electroweak mediators, we study a simplified model using as an example final states with tau leptons and neutrinos. Because one of the mediators is off shell and its decay products are extremely soft, it is challenging to make a discovery at the Large Hadron Collider. A Higgs factory such as the International Linear Collider, however, could serve as a discovery machine for such exotic Higgs decays even in an early stage.