119262345
Perturbative unitarity constraints on general W' models and collider implications
We study perturbative unitarity constraints on general W 0 models by considering the high energy behavior of fermion scattering into gauge bosons. In most cases we survey, a Z 0 boson with a comparable mass must be present for the theory to be consistent, with xed couplings to the standard model gauge bosons and fermions. Applying these results to a class of W 0 models which explains the top quark forward{backward asymmetry observed at the Tevatron, we nd that a Z 0 must exist with a mass below 7 8 TeV and sizable coupling to the light quarks. While such a Z 0 is strongly constrained by existing experiments, we show that the LHC can explore the entire mass range up to the unitarity limit. We also show how it is possible, by raising the Z 0 mass consistent with unitarity, to explain the CDF Wjj excess in terms of a light W 0 , without generating an excess in Zjj events.
30742433
Yukawa bound states of a large number of fermions
A bstractWe consider the bound state problem for a field theory that contains a Dirac fermion χ that Yukawa couples to a (light) scalar field ϕ. We are interested in bound states with a large number N of χ particles. A Fermi gas model is used to numerically determine the dependence of the radius R of these bound states on N and also the dependence of the binding energy on N. Since scalar interactions with relativistic χ’s are suppressed two regimes emerge. For modest values of N the state is composed of non-relativistic χ particles. In this regime as N increases R decreases. Eventually the core region becomes relativistic and the size of the state starts to increase as N increases. As a result, for fixed Yukawa coupling and χ mass, there is a minimum sized state that occurs roughly at the value of N where the core region first becomes relativistic. We also compute an elastic scattering form factor that can be relevant for direct detection if the dark matter is composed of such χ particles.
119109271
Type II Seesaw at LHC: The Roadmap
In this Letter we revisit the type-II seesaw mechanism based on the addition of a weak triplet scalar to the standard model. We perform a comprehensive study of its phenomenology at the LHC energies, complete with the electroweak precision constraints. We pay special attention to the doubly-charged component, object of collider searches for a long time, and show how the experimental bound on its mass depends crucially on the particle spectrum of the theory. Our study can be used as a roadmap for future complete LHC studies.
119306471
Inert Doublet Dark Matter and Mirror/Extra Families after Xenon100
J. Stefan Institute, Ljubljana, Slovenia(Dated: May 31, 2011)It was shown recently that mirror fermions, naturally present in a number of directions for newphysics, seem to require an inert scalar doublet in order to pass the electroweak precision tests.This provides a further motivation for considering the inert doublet as a dark matter candidate.Moreover, the presence of extra families enhances the Standard Model Higgs-nucleon coupling, whichhas crucial impact on the Higgs and dark matter searches. We study the limits on the inert darkmatter mass in view of recent Xenon100 data. We nd that the mass of the inert dark mattermust lie in a very narrow window 75 1GeV while the Higgs must weigh more than 400GeV. Forthe sake of completeness we discuss the cases with fewer extra families, where the possibility ofa light Higgs boson opens up, enlarging the dark matter mass window to
119264744
Effective angular momentum operators in NRQED and matching at one-loop order
We derive the effective angular momentum operator to 1/m2 and one-loop order in non-relativistic quantum electrodynamics (NRQED). In both dimensional and three-momentum-cutoff regularization schemes, we obtain the non-relativistic expansion for the spin and orbital angular momentum operators of the electron and photon, respectively. Our result is useful in precision calculations of the angular momentum properties for nonrelativistic QED bound states, such as atom systems.
19788205
CP-violating phenomenology of flavor conserving two Higgs doublet models
We analyze the constraints on CP-violating, flavor conserving two Higgs doublet models implied by measurements of Higgs boson properties at the Large Hadron Collider (LHC) and by the nonobservation of permanent electric dipole moments (EDMs) of molecules, atoms, and neutrons. We find that the LHC and EDM constraints are largely complementary, with the LHC studies constraining the mixing between the neutral CP-even states and the EDMs probing the effect of mixing between the CP-even and CP-odd scalars. Presently, the most stringent constraints are implied by the nonobservation of the ThO molecule EDM signal. Future improvements in the sensitivity of neutron and diamagnetic atom EDM searches could yield competitive or even more severe constraints. We analyze the quantitative impact of hadronic and nuclear theory uncertainties on the interpretation of the latter systems and conclude that these uncertainties cloud the impact of projected improvements in the corresponding experimental sensitivities.
118348335
Grand Unified Yukawa Matrix Ansatz: The Standard Model Fermion Mass, Quark Mixing and CP Violation Parameters
We propose a new mass matrix ansatz: At the grand unified (GU) scale, the standard model (SM) Yukawa coupling matrix elements are integer powers of the square root of the GU gauge coupling constant ε ≡ αGU, multiplied by order unity random complex numbers. It relates the hierarchy of the SM fermion masses and quark mixings to the gauge coupling constants, greatly reducing the SM parameters, and can give good fitting results of the SM fermion mass, quark mixing and CP violation parameters. This is a neat but very effective ansatz.
119300744
TeV scale universal seesaw, vacuum stability and heavy Higgs
A bstractWe discuss the issue of vacuum stability of standard model by embedding it within the TeV scale left-right universal seesaw model (called SLRM in the text). This model has only two coupling parameters (λ1, λ2) in the Higgs potential and only two physical neutral Higgs bosons (h, H). We explore the range of values for (λ1, λ2) for which the light Higgs boson mass Mh = 126 GeV and the vacuum is stable for all values of the Higgs fields. Combining with the further requirement that the scalar self couplings remain perturbative till typical GUT scales of order 1016 GeV, we find (i) an upper and lower limit on the second Higgs (H) mass to be within the range: 0.4 ≤ $ \frac{{{M_H}}}{{{v_R}}} $ ≤ 0.7, where the vR is the parity breaking scale and (ii) that the heavy vector-like top, bottom and τ partner fermions (P3, N3, E3) mass have an upper bound $ {M_{{{P_3},}}}_{{{N_3},{E_3}}}\leq {v_R} $. We discuss some phenomenological aspects of the model pertaining to LHC.
120528446
Some Remarks On the Extension of Loop-Groups
It is shown that in an anomalous Yang-Mills theory in 1+1 dimensions one can realise a non-central extension of a loop group, in addition to the well known central extension. The descent equations and Mickelsson's local coordinate techniques are used to construct 2-cocycles for the extended groups. It appears that in two-dimensional theories the central and non-central extensions of a loop group are compatible and equivalent to each other. The transition functions between different coordinate systems are also defined.
36920558
Determination of the Newtonian gravitational constant G with time-of-swing method.
We present a new value of the Newtonian gravitational constant G by using the time-of-swing method. Several improvements greatly reduce the uncertainties: (1) measuring the anelasticity of the fiber directly; (2) using spherical source masses minimizes the effects of density inhomogeneity and eccentricities; (3) using a quartz block pendulum simplifies its vibration modes and minimizes the uncertainty of inertial moment; (4) setting the pendulum and source masses both in a vacuum chamber reduces the error of measuring the relative positions. By two individual experiments, we obtain G = 6.673 49(18) x 10;{-11} m;{3} kg;{-1} s;{-2} with a standard uncertainty of about 2.6 parts in 10;{5}.
17226943
Superconformal Affine Liouville Theory
We present a superconformally invariant and integrable model based on the twisted affine KacMoody superalgebra ˆ osp(2|2) (2) which is the supersymmetrization of the purely bosonic conformal affine Liouville theory recently proposed by Babelon and Bonora. Our model reduces to the super-Liouville or to the super sinh-Gordon theories under certain limit conditions and can be obtained, via hamiltonian reduction, from a superspace WZNW model with values in the corresponding affine KM supergroup. The reconstruction formulae for classical solutions are given. The classical r-matrices in the homogeneous grading and the exchange algebras are worked out. Address after October 1, 1992: Laboratoire de Physique Théorique ENSLAPP, Ecole Normale Supérieure de Lyon, 46 Allée d’Italie, 69007 Lyon, France Address after 28 October 1992: Department of Mathematics, University of Queensland, Brisbane, Qld 4072, Australia