Upper Limit on the Cosmological Gamma-ray Background

We show that the current extragalactic gamma-ray background (EGB) measurement below 100 GeV sets an upper limit on EGB itself at very high energy (VHE) above 100 GeV. The limit is conservative for the electromagnetic cascade emission from VHE EGB interacting with the cosmic microwave-to-optical background radiation not to exceed the current EGB measurement. The cascade component fits the measured VHE EGB spectrum rather well. However, once we add the contribution from known source classes, the Fermi VHE EGB observation exceeds or even violates the limit, which is approximated as E^2dN/dE < 4.5x10^-5 (E/100 GeV)^-0.7 MeV/cm^2/s/sr. The upper limit above 100 GeV is useful in the future to probe the EGB origin and the new physics like axion-like particles and Lorentz-invariance violation.Comment: 8 pages, 8 figures, accepted for publication in PRD, Interested readers may wish to consult the recent paper by Murase, Beacom and Takami (arXiv:1205.5755

On the Physics Case of a Super Flavour Factory

We summarize the physics case of a high-luminosity e{sup +}e{sup -} flavor factory collecting an integrated luminosity of 50 - 75 ab{sup -1}. Many New Physics sensitive measurements involving B and D mesons and {tau} leptons, unique to a Super Flavor Factory, can be performed with excellent sensitivity to new particles with masses up to {approx} 100 (or even {approx} 1000) TeV. Flavor- and CP-violating couplings of new particles that may be discovered at the LHC can be measured in most scenarios, even in unfavorable cases assuming minimal flavor violation. Together with the LHC, a Super Flavor Factory, following either the SuperKEKB or the SuperB proposal, could be soon starting the project of reconstructing the New Physics Lagrangian

A High Luminosity e+e- Collider to study the Higgs Boson

A strong candidate for the Standard Model Scalar boson, H(126), has been discovered by the Large Hadron Collider (LHC) experiments. In order to study this fundamental particle with unprecedented precision, and to perform precision tests of the closure of the Standard Model, we investigate the possibilities offered by An e+e- storage ring collider. We use a design inspired by the B-factories, taking into account the performance achieved at LEP2, and imposing a synchrotron radiation power limit of 100 MW. At the most relevant centre-of-mass energy of 240 GeV, near-constant luminosities of 10^34 cm^{-2}s^{-1} are possible in up to four collision points for a ring of 27km circumference. The achievable luminosity increases with the bending radius, and for 80km circumference, a luminosity of 5 10^34 cm^{-2}s^{-1} in four collision points appears feasible. Beamstrahlung becomes relevant at these high luminosities, leading to a design requirement of large momentum acceptance both in the accelerating system and in the optics. The larger machine could reach the top quark threshold, would yield luminosities per interaction point of 10^36 cm^{-2}s^{-1} at the Z pole (91 GeV) and 2 10^35 cm^{-2}s^{-1} at the W pair production threshold (80 GeV per beam). The energy spread is reduced in the larger ring with respect to what is was at LEP, giving confidence that beam polarization for energy calibration purposes should be available up to the W pair threshold. The capabilities in term of physics performance are outlined.Comment: Submitted to the European Strategy Preparatory Group 01-04-2013 new version as re-submitted to PRSTA

An update for the MuCool test area

Construction of a new facility known as the MuCool Test Area (MTA) has been completed at Fermi National Accelerator Laboratory. This facility supports research in new accelerator technologies for future endeavors such as a Neutrino Factory or Muon Collider. During the summer of 2004, an initial set of tests was completed for the filling of a convection-style liquid hydrogen absorber designed by KEK. The absorber contained 6.2 liquid liters of hydrogen and was tested for a range of heating conditions to quantify the absorber's heat exchanger performance. Future work at Fermilab includes the design, construction, and installation of a forced-flow absorber to be used with other components built to investigate the properties of a muon ionization cooling channel. A Tevatron-style refrigerator/compressor building is to be operational by spring of 2006 in support of the absorber tests and also to provide 5-K helium and liquid nitrogen to a 5-T solenoid magnet, an active element of the future test apparatus. The refrigerator will be configured in such a manner as to meet the 5 K and 14-20-K helium needs of the MTA. This paper reviews the challenges and successes of the past KEK absorber tests as well as looks into the future cryogenic capabilities and intentions of the site

Search for Standard Model Higgs Boson Production in Association with a W Boson at CDF

We present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions (p{bar p} {yields} W{sup {+-}}H {yields} {ell}{nu}b{bar b}) at a center of mass energy of 1.96 TeV. The search employs data collected with the CDF II detector which correspond to an integrated luminosity of approximately 1 fb{sup -1}. We select events consistent with a signature of a single lepton (e{sup {+-}}/{mu}{sup {+-}}), missing transverse energy, and two jets. Jets corresponding to bottom quarks are identified with a secondary vertex tagging method and a neural network filter technique. The observed number of events and the dijet mass distributions are consistent with the standard model background expectations, and we set 95% confidence level upper limits on the production cross section times branching ratio ranging from 3.9 to 1.3 pb for Higgs boson masses from 110 to 150 GeV/c{sup 2}, respectively

Search for large extra dimensions in final states containing one photon or jet and large missing transverse energy produced in p anti-p collisions at s**(1/2) = 1.96-TeV

The authors present the results of searches for large extra dimensions in samples of events with large missing transverse energy E{sub T} and either a photon or a jet produced in p{bar p} collisions at {radical}s = 1.96 TeV collected with the CDF II detector. For {gamma} + E{sub T} and jet + E{sub T} candidate samples corresponding to 2.0 fb{sup -1} and 1.1 fb{sup -1} of integrated luminosity respectively, they observe good agreement with standard model expectations and obtain a combined lower limit on the fundamental parameter of the large extra dimensions model, M{sub D}, as a function of the number of extra dimensions in the model

Functional Requirements on the Design of the Detectors and the Interaction Region of an e e- Linear Collider with a Push-Pull Arrangement of Detectors

The Interaction Region of the International Linear Collider is based on two experimental detectors working in a push-pull mode. A time efficient implementation of this model sets specific requirements and challenges for many detector and machine systems, in particular the IR magnets, the cryogenics and the alignment system, the beamline shielding, the detector design and the overall integration. This paper attempts to separate the functional requirements of a push pull interaction region and machine detector interface from any particular conceptual or technical solution that might have been proposed to date by either the ILC Beam Delivery Group or any of the three detector concepts. As such, we hope that it provides a set of ground rules for interpreting and evaluating the MDI parts of the proposed detector concept's Letters of Intent, due March 2009. The authors of the present paper are the leaders of the IR Integration Working Group within Global Design Effort Beam Delivery System and the representatives from each detector concept submitting the Letters Of Intent