1,733 research outputs found

    CP Violation from 5-dimensional QED

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    It has been shown that QED in (1+4)-dimensional space-time, with the fifth dimension compactified on a circle, leads to CP violation (CPV). Depending on fermionic boundary conditions, CPV may be either explicit (through the Scherk--Schwarz mechanism), or spontaneous (via the Hosotani mechanism). The fifth component of the gauge field acquires (at the one-loop level) a non-zero vacuum expectation value. In the presence of two fermionic fields, this leads to spontaneous CPV in the case of CP-symmetric boundary conditions. Phenomenological consequences are illustrated by a calculation of the electric dipole moment for the fermionic zero-modes.Comment: 11 pages, 2 figure

    Rigorous theory of nuclear fusion rates in a plasma

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    Real-time thermal field theory is used to reveal the structure of plasma corrections to nuclear reactions. Previous results are recovered in a fashion that clarifies their nature, and new extensions are made. Brown and Yaffe have introduced the methods of effective quantum field theory into plasma physics. They are used here to treat the interesting limiting case of dilute but very highly charged particles reacting in a dilute, one-component plasma. The highly charged particles are very strongly coupled to this background plasma. The effective field theory proves that this mean field solution plus the one-loop term dominate; higher loop corrections are negligible even though the problem involves strong coupling. Such analytic results for very strong coupling are rarely available, and they can serve as benchmarks for testing computer models.Comment: 4 pages and 2 figures, presented at SCCS 2005, June 20-25, Moscow, Russi

    Programmable viscoelastic matrices from artificial proteins

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    Extracellular matrix compliance influences cellular adhesion and migration, proliferation and apoptosis, and differentiation. Much of our current knowledge of the effects of substrate stiffness on cellular behavior is based on elastic substrates, in particular cross‐linked polyacrylamide hydrogels. Biological tissues, however, are viscoelastic and exhibit stress relaxation and energy dissipation on physiologically relevant timescales. While emerging evidence suggests that these physical properties also influence cellular behavior, materials in which viscoelasticity can be precisely engineered are currently lacking. Here, we describe programmable hydrogel matrices assembled from artificial recombinant proteins designed to be cross‐linked by covalent bonds involving cysteine residues, by association of helical domains as coiled coils, or by both mechanisms. Using these proteins, we construct chemical, physical, and chemical‐physical hydrogel networks that deform elastically or viscoelastically depending on the type of cross‐linking (Dooling et al., Adv. Mater., 2016, 28, 4651–4657). In viscoelastic networks, the amount of stress relaxation is tuned by controlling the ratio of physical cross‐linking to chemical crosslinking, and the timescale for stress relaxation is tuned over five orders of magnitude by single point mutations to the coiled‐coil physical cross‐linking domain (Dooling and Tirrell, ACS Cent. Sci., 2016, 2, 812–819). The genetic engineering approach also allows biological activity to be encoded directly within the protein sequence in the form of cell‐adhesive domains and proteolytic cleavage sites. The capacity to program the viscoelasticity and biological activity of hydrogel matrices is anticipated to have applications in studying and engineering cell‐matrix interactions

    Higgs Boson Bounds in Three and Four Generation Scenarios

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    In light of recent experimental results, we present updated bounds on the lightest Higgs boson mass in the Standard Model (SM) and in the Minimal Supersymmetric extension of the Standard Model (MSSM). The vacuum stability lower bound on the pure SM Higgs boson mass when the SM is taken to be valid up to the Planck scale lies above the MSSM lightest Higgs boson mass upper bound for a large amount of SUSY parameter space. If the lightest Higgs boson is detected with a mass M_{H} < 134 GeV (150 GeV) for a top quark mass M_{top} = 172 GeV (179 GeV), it may indicate the existence of a fourth generation of fermions. The region of inconsistency is removed and the MSSM is salvagable for such values of M_{H} if one postulates the existence of a fourth generation of leptons and quarks with isodoublet degenerate masses M_{L} and M_{Q} such that 60 GeV 170 GeV.Comment: 7 pages, 4 figures. To be published in Physical Review

    CP Violation from Dimensional Reduction: Examples in 4+1 Dimensions

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    We provide simple examples of the generation of complex mass terms and hence CP violation through dimensional reduction.Comment: 6 pages, typos corrected, 1 reference adde

    A model of CP Violation from Extra Dimension

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    We construct a realistic model of CP violation in which CP is broken in the process of dimensional reduction and orbifold compactification from a five dimensional theories with SU(3)×SU(3)×SU(3)SU(3)\times SU(3) \times SU(3) gauge symmetry. CP violation is a result of the Hosotani type gauge configuration in the higher dimension.Comment: 5 page

    Sum Rules of Neutrino Masses and CP Violation in the Four-Neutrino Mixing Scheme

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    We show that the commutator of lepton mass matrices is invariant under terrestial matter effects in the four-neutrino mixing scheme. A set of model-independent sum rules for neutrino masses, which may be generalized to hold for an arbitrary number of neutrino families, are for the first time uncovered. Useful sum rules for the rephasing-invariant measures of leptonic CP violation have also been found. Finally we present a generic formula of T-violating asymmetries and expect it to be applicable to the future long-baseline neutrino oscillation experiments.Comment: RevTex 8 pages. 3 references added. Phys. Rev. D (in printing

    Report of the Beyond the MSSM Subgroup for the Tevatron Run II SUSY/Higgs Workshop

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    There are many low-energy models of supersymmetry breaking parameters which are motivated by theoretical and experimental considerations. Here, we discuss some of the lesser-known theories of low-energy supersymmetry, and outline their phenomenological consequences. In some cases, these theories have more gauge symmetry or particle content than the Minimal Supersymmetric Standard Model. In other cases, the parameters of the Lagrangian are unusual compared to commonly accepted norms (e.g., Wino LSP, heavy gluino LSP, light gluino, etc.). The phenomenology of supersymmetry varies greatly between the different models. Correspondingly, particular aspects of the detectors assume greater or lesser importance. Detection of supersymmetry and the determination of all parameters may well depend upon having the widest possible view of supersymmetry phenomenology.Comment: 78 pages, 49 figures, to appear in the Proceedings of the Tevatron Run II SUSY/Higgs Workshop. Editor: J. F. Gunion; BTMSSM Convenors: M. Chertok, H. Dreiner, G. Landsberg, J. F. Gunion, J.D. Well
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