The Scientific Need for a Scalar/Higgs Factory

The scalar sector of the electroweak theory can be probed by a mu^+mu^- collider S channel resonance machine. We give arguments for when such a machine may be needed and when this information could be obtained by the LHC detector. A very interesting case is the possibility that several scalar particles are in the same mass range for the supersymmetric Higgs bosons h, H, and A, which would definitely require such a machine. The Higgs factory could follow the construction of a neutrino factory.Comment: 6 pages. Presented at the 5th Int. Conf. sponsored by UCLA on the Physics Potential and Development of mu^+mu^- Colliders (San Francisco, Dec. 15-17, 1999) and to be published in the Proceedings by AI

A Neutrino-Factory Muon Storage Ring to Provide Beams for Multiple Detectors Around the World

We briefly discuss the physics motivation for a neutrino factory with varying baseline distances of about 1000 to 9000 km. We describe the amount of non planarity of the storage ring required to service three or four detectors at once. A novel bowtie storage ring is described that could in part provide these beams; a preliminary lattice design is given. We give the space angles between the various detector locations and possible sites for neutrino factories. Finally we describe detectors at the Gran Sasso Laboratory and at a new laboratory near Carlsbad, NM to observe the neutrino interactions with wrong sign leptons.Comment: 8 pages. Presented at the 5th Int. Conf. sponsored by UCLA on the Physics Potential and Develoment of mu^+mu^- Colliders (San Francisco, December 15-17, 1999) and to be published in the Proceedings by AI

Observations of cosmic gamma-ray bursts with IMP-7: Evidence for a single spectrum

Spectral observation of nine recent cosmic gamma-ray bursts are reported. The average photon number spectra of all nine events are shown to be consistent with a 150-keV exponential from 100 keV to about 400 keV, and a power law of index -2.5 from 400 keV to 1100 keV. The observations also indicate an event rate of 16 in 1972 and 1973, or 8 + or - 2 per year, higher than the 5 + or - 1 per year initially reported. This corresponds to an approximately 40-percent lower effective intensity threshold, attained by using more sensitive detectors in multiple-satellite coincidence

Testing neutrino spectra formation in collapsing stars with the diffuse supernova neutrino flux

I address the question of what can be learned from the observation of the diffuse supernova neutrino flux in the precision phase, at next generation detectors of Megaton scale. An analytical study of the spectrum of the diffuse flux shows that, above realistic detection thresholds of 10 MeV or higher, the spectrum essentially reflects the exponential-times-polynomial structure of the original neutrino spectrum at the emission point. There is only a weak (tens of per cent) dependence on the power \beta describing the growth of the supernova rate with the redshift. Different original neutrino spectra correspond to large differences in the observed spectrum of events at a water Cerenkov detector: for typical supernova rates, the ratio of the numbers of events in the first and second energy bins (of 5 MeV width) varies in the interval 1.5 - 4.3 for pure water (energy threshold 18 MeV) and in the range 1 - 2.5 for water with Gadolinium (10 MeV threshold). In the first case discrimination would be difficult due to the large errors associated with background. With Gadolinium, instead, the reduction of the total error down to 10-20 % level would allow spectral sensitivity, with a dramatic improvement of precision with respect to the SN1987A data. Even in this latter case, for typical neutrino luminosity the dependence on \beta is below sensitivity, so that it can be safely neglected in data analysis.Comment: LaTeX, 10 pages, 5 figures; details added to fig. 5 and related text, minor modifications to the text, references added. Version in press in Phys.Rev.D

Unlocking Undergraduate Problem Solving

It is difficult to find good problems for undergraduates. In this article, we explore an interesting problem that can be used in virtually any mathematics course. We then offer natural generalizations, state and prove some related results, and ultimately end with several open problems suitable for undergraduate research. Finally, we attempt to shed some light on what makes a problem interesting

Composite magnetic dark matter and the 130 GeV line

We propose an economical model to explain the apparent 130 GeV gamma ray peak, found in the Fermi/LAT data, in terms of dark matter annihilation through a dipole moment interaction. The annihilating dark matter particles represent a subdominant component, with mass density 7-17% of the total DM density; and they only annihilate into gamma gamma, gamma Z, and ZZ, through a magnetic (or electric) dipole moment. Annihilation into other standard model particles is suppressed, due to a mass splitting in the magnetic dipole case, or to p-wave scattering in the electric dipole case. In either case, the observed signal requires a dipole moment of strength mu ~ 2/TeV. We argue that composite models are the preferred means of generating such a large dipole moment, and that the magnetic case is more natural than the electric one. We present a simple model involving a scalar and fermionic techniquark of a confining SU(2) gauge symmetry. We point out some generic challenges for getting such a model to work. The new physics leading to a sufficiently large dipole moment is below the TeV scale, indicating that the magnetic moment is not a valid effective operator for LHC physics, and that production of the strongly interacting constituents, followed by techni-hadronization, is a more likely signature than monophoton events. In particular, 4-photon events from the decays of bound state pairs are predicted.Comment: 8 pages, 5 figures; v2. fixed typos, clarifications, added discussion of model-building challenges; v3. clarifications added, discussion improved, accepted for publication in PR

Resolution of Nearly Mass Degenerate Higgs Bosons and Production of Black Hole Systems of Known Mass at a Muon Collider

The direct s-channel coupling to Higgs bosons is 40000 times greater for muons than electrons; the coupling goes as mass squared. High precision scanning of the lighter $h^0$ and the higher mass $H^0$ and $A^0$ is thus possible with a muon collider. The $H^0$ and $A^0$ are expected to be nearly mass degenerate and to be CP even and odd, respectively. A muon collider could resolve the mass degeneracy and make CP measurements. The origin of CP violation in the $K^{0}$ and $B^{0}$ meson systems might lie in the the $H^0/A^0$ Higgs bosons. If large extra dimensions exist, black holes with lifetimes of $\sim 10^{-26}$ seconds could be created and observed via Hawking radiation at the LHC. Unlike proton or electron colliders, muon colliders can produce black hole systems of known mass. This opens the possibilities of measuring quantum remnants, gravitons as missing energy, and scanning production turn on. Proton colliders are hampered by parton distributions and CLIC by beamstrahlung. The ILC lacks the energy reach.Comment: Latex, 5 pages, 2 figures, proceedings to the DPF 2004: Annual Meeting of the Division of Particles and Fields of APS, 26 August-31 August 2004, Riverside, CA, US