134388752
Design study of 15-Tesla RHQT Nb3Al block type dipole magnet
The design study of the block type 15-Tesla RHQT Nb{sub 3}Al dipole magnet, and its merits over Nb{sub 3}Sn magnets are presented. The copper stabilized RHQT Nb{sub 3}Al strand is now becoming commercially available for the application to the accelerator magnets. A 1 mm diameter RHQT Nb{sub 3}Al strand with filament size about 50 {mu}, non-copper Jc about 1000 A/mm{sup 2} at 15 Tesla at 4.2K, copper ratio of 50%, can now be produced over several hundred meters. The stress and strain characteristics of the Nb{sub 3}Al strand are superior to the Nb{sub 3}Sn strand. Another advantage is that it can tolerate a longitudinal strain up to 0.55%. The RHQT Nb{sub 3}Al Rutherford cable will have less chance of contamination of the stabilizer, compared to Nb{sub 3}Sn cable. These characteristics of the RHQT Nb{sub 3}Al will be beneficial for designing and producing 15-Tesla dipole magnets. An example 15-Tesla magnet cross section, utilizing the RHQT Nb{sub 3}Sn strand is presented. A systematic investigation on RHQT Nb{sub 3}Al strands, its Rutherford cables, and building a small racetrack magnet for cable testing are proposed.
140060327
Nb-3_Al high field accelerator magnet \&
215736286
STATUS AND PERSPECTIVE OF THE NB3AL DEVELOPMENT IN JAPAN
The RHQT process enables to form a stoichiometric Nb3Al with fine-grain structures via a bcc supersaturated solid solution and so that a large Jc is achieved over the whole range of magnetic fields without trading off the excellent strain tolerance. A long-length of RHQ processing has been established, and a rectangular but Cu stabilized Nb3Al strand is about to be commercially available for NMR uses. Another stabilization technique has been developed and likely applicable to accelerator uses. Research activities at the KEK with respect to the low field Jc characterization are also described.
119349560
Constraints on two-Higgs-doublet models at large tan {beta} from W and Z decays
We study constraints on type-II two-Higgs-doublet models at large tan {beta} from CERN LEP and SLD Z-pole data and from lepton universality violation in W decay. We perform a global fit and find that, in the context of Z decay, the LEP-SLD experimental values for lepton universality violation, R{sub b}, and A{sub b} all somewhat disfavor the model. Contributions from the neutral-Higgs sector can be used to constrain the scalar-pseudoscalar Higgs mass splittings. Contributions from the charged-Higgs sector allow us to constrain the charged-Higgs boson mass. For tan {beta}=100 we obtain the 1{sigma} classical (Bayesian) bounds of m{sub H{sup {+-}}}{>=}670 GeV (370 GeV) and 1{>=}m{sub h{sup 0}}/m{sub A{sup 0}}|{sub {alpha}}{sub ={beta}}=m{sub H{sup 0}}/m{sub A{sup 0}}|{sub {alpha}}{sub =0}{>=}0.68 (0.64). The 2{sigma} bounds are weak. Currently, the Fermilab Tevatron experimental limits on lepton universality violation in W decay provide no significant constraint on the Higgs sector. (c) 2000 The American Physical Society.
119272601
Ratchet Model of Baryogenesis
We propose a toy model of baryogenesis which applies the ‘ratchet mechanism,’ used frequently in the theory of biological molecular motors, to a model proposed by Dimopoulos and Susskind.
119450303
Indirect probes of new physics
We summarize the indirect effects of new physics in a variety of processes. We consider precision electroweak measurements, the $g-2$ of the muon, rare decays, meson mixing, CP violation, lepton number violating interactions, double beta decay, and the electric dipole moments of atoms, molecules, and the neutron. We include discussions of both model independent and dependent analyses where applicable.
119989444
Future constraints on and from lepton universality
In the near future, experimental constraints on charged current (CC) lepton universality can be expected to improve dramatically. First, the PIENU experiment at TPIUMF and the PEN experiment at PSI aim to improve the bound on the ratio by almost an order of magnitude. Second, by analyzing existing data, the Belle experiment aims to improve the bound on the ratio by a factor of three. Further improvements can be expected by analyzing the τ decays in existing Belle data. There also exist a large amount of unanalyzed W decay data from the Tevatron. These new bounds will place very tight constraints on possible new physics beyond the Standard Model. For example, the 95% bounds on R-parity violating couplings will be improved as follows: These limits will be very difficult to improve further, even with future high statistics neutrino experiments such as NuSOnG [1]. However, for certain types of new physics, the combination of CC lepton universality data and NuSOnG will have a dramatic effect. I demonstrate this using a model in which neutrino mixing with heavy gauge singlet states suppress both the CC and NC neutrino couplings.