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.
119264713
Measuring Di-Higgs Physics via the $t \bar t hh \to t \bar t b \bar bb\bar b$ Channel
The measurement of di-Higgs physics can provide crucial information on electroweak phase transition in the early Universe and significant clues on new physics coupling with the Higgs field directly. This measurement has been suggested to be pursued mainly via the $pp \to hh$ production. In this letter, we propose a new strategy to do that, i.e., via the $pp \to t \bar t hh $ production. Because of its positive correlation with the rescaled tri-Higgs coupling $\frac{\lambda}{\lambda_{\rm SM}}$ (in comparison to a negative one for the $pp \to hh$ production) in the neighborhood of $\frac{\lambda}{\lambda_{\rm SM}} \sim 1$, the $pp \to t\bar t hh$ production complements the $pp \to hh$ one in measuring di-Higgs physics, particularly for $\frac{\lambda}{\lambda_{\rm SM}}>1$, at both the High Luminosity LHC (HL-LHC) and a next-generation $pp$-collider. As an illustration, we work on the process $pp\to t\bar thh \to t\bar t b\bar b b\bar b$. We show that a statistical significance of $> 2.0 \sigma$ at the HL-LHC, comparable to that of the $pp \to hh \to b\bar b \gamma\gamma$ channel, and a statistical significance of $\sim 5 \sigma$ at a 100 TeV $pp$-collider, with 3000 fb$^{-1}$ of data, are achievable in searching for the di-Higgs production with $\frac{\lambda}{\lambda_{\rm SM}} = 1$.
119074364
Post-ACME2013 CP-violation in Higgs Physics and Electroweak Baryogenesis
We present a class of cancellation mechanisms to suppress the total contributions of Barr-Zee diagrams to the electron electric dipole moment (eEDM). This class of mechanisms are of particular significance after the new eEDM upper limit, which strongly constrains the allowed magnitude of CP-violation in Higgs couplings and hence the feasibility of electroweak baryogenesis (EWBG), were released by the ACME collaboration in 2013. We point out: if both the CP-odd Higgs-photonphoton (Z boson) and the CP-odd Higgs-electron-positron couplings are turned on, a cancellation may occur either between the contributions of a CP-mixing Higgs boson, with the other Higgs bosons being decoupled, or between the contributions of a CP-even and a CP-odd Higgs bosons. With the assistance of the cancellation mechanisms, a large CP-phase in Higgs couplings with viable electroweak baryogenesis (EWBG) is still allowed. The reopened parameter regions would be probed by the future neutron, mercury EDM measurements, and direct measurements of Higgs CP-properties at the LHC and future colliders.
118316245
Exotic Higgs Decay h to 2a at the International Linear Collider: a Snowmass White Paper
A Higgs factory like the International Linear Collider (ILC) can play a significant role in searching for exotic decays of Higgs bosons. As an illustration, we investigate the ILC sensitivity for the decay topology $h\to a_1 a_1 \to \tau\bar \tau\tau \bar \tau$ in the Next-to-Minimal-Supersymmetric-Standard-Model (NMSSM). Here $h$ can be either Standard-Model-like or non-standard, and $a_{1}$ is the lightest CP-odd Higgs boson. We also compare results to expectations for this channel at the LHC.
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.
119444679
Supersymmetric standard models, flux compactification and moduli stabilization
Abstract Based on the T-dual constructions of supersymmetric intersecting D6-models on Z 2 × Z 2 orientifolds, whose electroweak sector is parallel with the orientifold planes with Sp ( 2 f ) L × Sp ( 2 f ) R gauge symmetry [ hep-th/0407178 ], we derive and classify standard model-like vacua with RR and NSNS fluxes, which stabilize toroidal complex structure moduli and the dilaton. We find consistent four-family ( f = 4 ) and two-family ( f = 2 ) models with one- and two-units of the quantized flux, respectively. Such models typically possess additional gauge group factors with negative beta functions and may lead, via gaugino condensation, to stabilization of toroidal Kahler moduli. These models have chiral exotics.
9969479
Pseudo-goldstino and electroweakinos via VBF processes at LHC
A bstractThe multi-sector SUSY breaking predicts pseudo-goldstino which can couple to the visible sector more strongly than the ordinary gravitino and thus induce the decays of the lightest neutralino and chargino (collectively called electroweakinos) inside the detector. In this note we study the electroweakino pair productions via VBF processes followed by decays to pseudo-goldstino at the LHC. Our Monte Carlo simulations show that at the 14 TeV LHC with 3000 fb−1 luminosity the dominant production channel pp → χ1∓χ10jj can have a statistical significance above 2σ while other production channels are not accessible.
122901102
LABORATORY ASTROPHYSICS IN TAIWAN
We report the development of laboratory astrophysics program in Taiwan. We begin with outlining Taiwan's participation in the FLASH collaboration for measuring the fluorescence yield using SLAC 28.5 GeV electron beam. We then report the domestic effort of studying cosmic ray shower properties using NSRRC 1.5 GeV electron beam.
53310241
COSMOGENIC TAU NEUTRINO INDUCED RADIO EMISSION
Cosmogenic neutrinos1 are expected from ultrahigh energy cosmic rays undergoing the GZK process2,3 and anticipated to be observed by detection of the air showers from the decays of tau leptons. We use CORSIKA simulated shower structure to Calculate the coherent geosynchrotron radio emissions of the tau decay showers above 1017 eV. We present the pattern and spectrum of the radio waves and discuss their detections by radio antennae.
121725222
Optical links for ATLAS liquid argon calorimeter front-end electronics readout
We present the optical data links for the ATLAS liquid argon calorimeter. The current status of the vertical cavity surface emitting laser failures, the up-to-date results in searching for the failure cause, experiences gained in the searching process, possible backup plans for the optical transmitters and the lessons learned are also discussed.
55746504
The versatile link, a common project for super-LHC
A common project to develop a bi-directional, radiation tolerant, high speed (4.8 Gb/s) optical link for future high energy physics experiments is described. Due to be completed in 2012, it targets the upgrade programs of detectors installed at CERN's Large Hadron Collider (LHC). The development of radiation and magnetic field tolerant opto-electronic devices, fibre and connectors is described. Both Single-Mode and Multi-Mode versions of the system operating respectively at 850 nm and 1310 nm wavelength are proposed. First results at component and system level are presented, based mostly on commercially available devices.