Will Loinaz

Theory of neutrinos: a white paper

This paper is a review of the present status of neutrino mass physics, which grew out of an APS sponsored study of neutrinos in 2004. After a discussion of the present knowledge of neutrino masses and mixing and some popular ways to probe the new physics implied by recent data, it summarizes what can be learned about neutrino interactions as well as the nature of new physics beyond the Standard Model from the various proposed neutrino experiments. The intriguing possibility that neutrino mass physics may be at the heart of our understanding of a long standing puzzle of cosmology, i.e. the origin of matter?antimatter asymmetry is also discussed.

An Improved lattice measurement of the critical coupling in phi(2)**4 theory

We use Monte Carlo simulations to obtain an improved lattice measurement of the critical coupling constant [{lambda}/{mu}{sup 2}]{sub crit} for the continuum (1+1)-dimensional ({lambda}/4){phi}{sup 4} theory. We find that the critical coupling constant depends logarithmically on the lattice coupling, resulting in a continuum value of [{lambda}/{mu}{sup 2}]{sub crit}=10.8{sub -0.05}{sup +0.10}, in considerable disagreement with the previously reported [{lambda}/{mu}{sup 2}]{sub crit}=10.26{sub -0.04}{sup +0.08}. Although this logarithmic behavior was not observed in earlier lattice studies, it is consistent with them, and expected analytically.

Higgs boson interactions in supersymmetric theories with large tanβ

Abstract We show that radiative corrections to the Higgs potential in supersymmetric theories with large tan β generically lead to large differences in the light Higgs boson decay branching fractions compared to those of the standard model Higgs boson. In contrast, the light Higgs boson production rates are largely unaffected. We identify Wh associated production followed by Higgs boson decays to photons or to leptons via WW ∗ as potential experimental probes of these theories.

Terascale Physics Opportunities at a High Statistics, High Energy Neutrino Scattering Experiment: NuSOnG

This paper presents the physics case for a new high-energy, ultra-high statistics neutrino scattering experiment, NuSOnG (Neutrino Scattering on Glass). This experiment uses a Tevatron-based neutrino beam to obtain over an order of magnitude higher statistics than presently available for the purely weak processes νμ + e- → νμ + e- and νμ + e- → νe + μ-. A sample of Deep Inelastic Scattering events which is over two orders of magnitude larger than past samples will also be obtained. As a result, NuSOnG will be unique among present and planned experiments for its ability to probe neutrino couplings to Beyond the Standard Model physics. Many Beyond Standard Model theories physics predict a rich hierarchy of TeV-scale new states that can correct neutrino cross-sections, through modifications of Zνν couplings, tree-level exchanges of new particles such as Z′s, or through loop-level oblique corrections to gauge boson propagators. These corrections are generic in theories of extra dimensions, extended gauge symmetries, supersymmetry, and more. The sensitivity of NuSOnG to this new physics extends beyond 5 TeV mass scales. This paper reviews these physics opportunities.

Universal Torsion Induced Interaction from Large Extra Dimensions

We consider the Kaluza-Klein (KK) scenario in which only gravity exists in the bulk. Without the assumption of symmetric connection, the presence of brane fermions induces torsion. The result is a universal axial contact interaction that dominates those induced by KK gravitons. This enhancement arises from a large spin density on the brane. Using a global fit to Z-pole observables, we find the 3sigma bound on the scale of quantum gravity to be 28 TeV for n = 2. If Dirac or light sterile neutrinos are present, the data from SN1987A increase the bound to sqrt[n] M(S)>/=210 TeV.

Quark lepton unification and lepton flavor nonconservation from a TeV scale seesaw neutrino mass texture

In a recent paper, we pointed out that mixing of the light neutrinos with heavy gauge singlet states could reconcile the Z-pole data from e + e − colliders and the �� (¯�� ) scattering data from the NuTeV experiment at Fermilab. We further noted that the mixing angle required to fit the data is much larger than what would be expected from the conventional seesaw mechanism. In this paper, we show how such mixings can be arranged by a judicious choice of the neutrino mass texture. We also argue that by invoking the unification of the Dirac mass matrix for the up-type quarks and the neutrinos, the mass of the heavy states can naturally be expected to lie in the few TeV range. The model is strongly constrained by the lepton flavor changing process µ → e which requires lepton universality to be violated in the charged channel.

Constraints on top-color assisted technicolor models from vertex corrections

We use the LEP-SLD data to place constraints on top-color assisted technicolor models. We find that, due to a large negative shift in R{sub b} induced by charged top-pion exchange, it is difficult to make the models compatible with experiment. {copyright} {ital 1999} {ital The American Physical Society}

Monte Carlo Simulation Calculation of Critical Coupling Constant for Continuum \phi^4_2

We perform a Monte Carlo simulation calculation of the critical coupling constant for the continuum {\lambda \over 4} \phi^4_2 theory. The critical coupling constant we obtain is [{\lambda \over \mu^2}]_crit=10.24(3).

Quantum revivals and carpets in some exactly solvable systems

We consider the revival properties of quantum systems with an eigenspectrum En n2, and compare them with the simplest member of this class - the infinite square well. In addition to having perfect revivals at integer multiples of the revival time tR, these systems all enjoy perfect fractional revivals at quarterly intervals of tR. A closer examination of the quantum evolution is performed for the Poschel-Teller and Rosen-Morse potentials, and comparison is made with the infinite square well using quantum carpets.

Critical dimensions of the diffusion equation.

We study the evolution of a random initial field under pure diffusion in various space dimensions. From numerical calculations we find that the persistence properties of the system show sharp transitions at critical dimensions d(1) approximately 26 and d(2) approximately 46. We also give refined measurements of the persistence exponents for low dimensions.