55543374
Supersymmetric subelectroweak scale dark matter, the Galactic Center gamma-ray excess, and exotic decays of the 125 GeV Higgs boson
We continue our exploration of the nearly Peccei-Quinn symmetric limit shared by common singlet extensions of the Minimal Supersymmetric Standard Model. This limit has been established as a viable framework for studying sub-electroweak scale dark matter phenomenology and has interesting and direct connections to new exotic Higgs decay physics. We present analytic calculations to motivate the important phenomenological features mentioned above. We also discuss benchmark points in this model framework that accommodate the observed Galactic Center gamma ray excess. We emphasize connections between phenomenology of dark matter direct detection and indirect detection, and new exotic decay channels for the 125 GeV Higgs boson. We conclude by identifying two benchmark modes of exotic Higgs decays for h ! + 6ET and h ! b b6ET nal states and estimate their sensitivity prospects at the LHC.
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 $\frac{\lambda}{\lambda_{\rm SM}} = 1$.
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.
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.
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.
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.
30481535
A compact apparatus for muon lifetime measurement and time dilation demonstration in the undergraduate laboratory
We describe a compact apparatus for measuring the charge-averaged lifetime of atmospheric muons in plastic scintillator using low-cost, low-power electronics. We present measurements of the stopping rate of atmospheric muons as a function of altitude to demonstrate relativistic time dilation. The apparatus is designed for the advanced undergraduate physics laboratory and is suitable for field measurements.
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.
118568439
Active inductor shunt peaking in high-speed VCSEL driver design
An all transistor active inductor shunt peaking structure has been used in a prototype of 8-Gbps highspeed VCSEL driver which is designed for the optical link in ATLAS liquid Argon calorimeter upgrade. The VCSEL driver is fabricated in a commercial 0.25-μm Silicon-on-Sapphire (SoS) CMOS process for radiation tolerant purpose. The all transistor active inductor shunt peaking is used to overcome the bandwidth limitation from the CMOS process. The peaking structure has the same peaking effect as the passive one, but takes a small area, does not need linear resistors and can overcome the process variation by adjust the peaking strength via an external control. The design has been tapped out, and the prototype has been proofed by the preliminary electrical test results and bit error ratio test results. The driver achieves 8-Gbps data rate as simulated with the peaking. We present the all transistor active inductor shunt peaking structure, simulation and test results in this paper.
118803187
Angular momentum decomposition from a QED example
We investigate the angular momentum decomposition with a quantum electrodynamics example to clarify the proton spin decomposition debates. We adopt the light-front formalism where the parton model is well defined. We prove that the sum of fermion and boson angular momenta is equal to half the sum of the two gravitational form factors $A(0)$ and $B(0)$, as is well known. However, the suggestion to make a separation of the above relation into the fermion and boson pieces, as a way to measure the orbital angular momentum of fermions or bosons, respectively, is not justified from our explicit calculation.
119232315
Quark orbital motions from Wigner distributions
We investigate quark Wigner distributions in a light-cone spectator model. Both the scalar and the axial-vector spectators are included. The light-cone wave functions are derived from effective quark-spectator-nucleon vertex and then generalized by adjusting the power of energy denominators. The gauge link is taken into account by introducing relative phases to the light-cone amplitudes, and the phases are estimated from one gluon exchange interactions. The mixing distributions, which describe the correlation between transverse coordinate and transverse momentum and represent quark orbital motions, are calculated from the Wigner distributions. We find both $u$ quark and $d$ quark have positive orbital angular momentum in a polarized proton at small $x$ region, but a sign change is observed at large $x$ region for the $d$ quark. Besides, some model relations between Wigner distributions with different polarization configurations are found.