Pair-production of Higgs bosons via heavy quark annihilation

Upper bounds on the cross section for production of Higgs boson pairs via heavey quark fusion are determined for various masses. The rates are compared with the contribution to Higgs pair-production from gauge boson fusion.     

Production characteristics of charmed particles in neutrino interactions

Using a hybrid emulsion spectrometer installed in the Fermilab wide-band neutrino beam, we located a total of 3855 neutrino interactions in the fiducial volume of our target. For 122 charmed-particle decays found in these interactions, we present distributions of x,y, charm-muon angular projection, Feynman-X, and the fragmentation Z. We find that the number of strange quarks in the nucleon sea is 4.2±2.1±2.6% of the number of down quarks.     

Asymmetric Host Molecule Bearing Pyridine Core for Highly Efficient Blue Thermally Activated Delayed Fluorescence OLEDs

In this study, two host materials, pCzBzbCz and pCzPybCz , are synthesized to achieve a high efficiency and long lifetime of blue thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs). The molecular design strategy involves the introduction of a pyridine group into the core structure of pCzPybCz as an electron-withdrawing unit, and an electron-donating phenyl group into the structure of pCzBzbCz . These host materials demonstrate good thermal stability and high triplet energy (T₁=3.07 eV for pCzBzbCz and 3.06 eV for pCzPybCz ) for the fabrication of blue TADF-OLEDs. In particular, pCzPybCz -based OLED devices demonstrate an external quantum efficiency (EQE) of 22.7 % and an operational lifetime of 24 h (LT₉₀, time to attain 90 % of initial luminance) at an initial luminance of 1000 cd m⁻². This superior lifetime could be explained by the C−N bond dissociation energy (BDE) in the host molecular structure. Furthermore, a mixed-host system using the electron-deficient 2,4-bis(dibenzo[b,d]furan-2-yl)-6-phenyl-1,3,5-triazine (DDBFT) is proposed to inhibit the formation of the anion state of our host materials. In short, the device operational lifetime is further improved by applying DDBFT. The carbazole-based asymmetric host molecule containing a pyridine core realizes a high-efficiency blue TADF-OLED showing a positive effect on the operating lifetime, and can provide useful strategies for designing new host materials.     

A Simple Method for the Preparation of Substituted Phenoxyacrylic Acid Phenyl Esters

A simple and efficient synthesis of phenoxyacrylic acid phenyl esters via one pot esterification and Michael-type addition starting from propynoic acid and an excess of an appropriate phenol is described.     

From the LHC to future colliders

Discoveries at the LHC will soon set the physics agenda for future colliders. This report of a CERN Theory Institute includes the summaries of Working Groups that reviewed the physics goals and prospects of LHC running with 10 to 300 fb^?1 of integrated luminosity, of the proposed sLHC luminosity upgrade, of the ILC, of CLIC, of the LHeC and of a muon collider. The four Working Groups considered possible scenarios for the first 10 fb^?1 of data at the LHC in which (i) a state with properties that are compatible with a Higgs boson is discovered, (ii) no such state is discovered either because the Higgs properties are such that it is difficult to detect or because no Higgs boson exists, (iii) a missing-energy signal beyond the Standard Model is discovered as in some supersymmetric models, and (iv) some other exotic signature of new physics is discovered. In the contexts of these scenarios, the Working Groups reviewed the capabilities of the future colliders to study in more detail whatever new physics may be discovered by the LHC. Their reports provide the particle physics community with some tools for reviewing the scientific priorities for future colliders after the LHC produces its first harvest of new physics from multi-TeV collisions.