Majorana neutrinos and lepton-number-violating signals in top-quark and W-boson rare decays

We discuss rare lepton-number-violating top-quark and W-boson four-body decays to final states containing a same-charge lepton pair, of the same or of different flavors: t -> b W- li^+ lj^+ and W+ -> J J' li^+ lj^+, where i \ne j or i=j and J J' stands for two light jets originating from a (u-bar d) or a (c-bar s) pair. These \Delta L=2 decays are forbidden in the Standard Model and may be mediated by exchanges of Majorana neutrinos. We adopt a model independent approach for the Majorana neutrinos mixing pattern and calculate the branching ratios (BR) for these decays. We find, for example, that for O(1) mixings between heavy and light Majorana neutrinos (not likely but not ruled out) and if at least one of the heavy Majorana neutrinos has a mass of ~100 GeV, then the BR's for these decays are: BR(t -> b li^+ lj^+ W-) ~ 10^{-4} and BR(W+ -> li^+ lj^+ J J') ~ 10^{-7} if m_N ~ 100 GeV and BR(t -> b li^+ lj^+ J J') ~ BR(W+ -> li^+ lj^+ J J') ~ 0.01 if m_N < 50 GeV. Taking into account the present limits on the neutrino mixing parameters, we obtain more realistic values for these BR's: BR(t -> b li^+ lj^+ W-) ~ 10^{-6} and BR(W+ -> li^+ lj^+ J J') ~ 10^{-10} for m_N ~ 100 GeV and BR(t -> b li^+ lj^+ J J') ~ BR(W+ -> li^+ lj^+ J J') ~ 10^{-6} for m_N < 50 GeV.Comment: latex, 7 pages, 2 figures. V2 as published in PL

Magnetic fields of our Galaxy on large and small scales

Magnetic fields have been observed on all scales in our Galaxy, from AU to kpc. With pulsar dispersion measures and rotation measures, we can directly measure the magnetic fields in a very large region of the Galactic disk. The results show that the large-scale magnetic fields are aligned with the spiral arms but reverse their directions many times from the inner-most arm (Norma) to the outer arm (Perseus). The Zeeman splitting measurements of masers in HII regions or star-formation regions not only show the structured fields inside clouds, but also have a clear pattern in the global Galactic distribution of all measured clouds which indicates the possible connection of the large-scale and small-scale magnetic fields.Comment: 9 pages. Invited Talk at IAU Symp.242, 'Astrophysical Masers and their Environments', Proceedings edited by J. M. Chapman & W. A. Baa

Direct Observation of Long-Term Durability of Superconductivity in YBa2_2Cu3_3O7_7-Ag2_2O Composites

We report direct observation of long-term durability of superconductivity of several YBa$_2$Cu$_3$O$_7$-Ag$_2$O composites that were first prepared and studied almost 14 years ago [J. J. Lin {\it et al}., Jpn. J. Appl. Phys. {\bf 29}, 497 (1990)]. Remeasurements performed recently on both resistances and magnetizations indicate a sharp critical transition temperature at 91 K. We also find that such long-term environmental stability of high-temperature superconductivity can only be achieved in YBa$_2$Cu$_3$O$_7$ with Ag$_2$O addition, but not with pure Ag addition.Comment: to be published in Jpn. J. Appl. Phy

HAN

Tuesday, September 07, 2004, 10:30 EDT (10:30 AM EDT)CDCHAN-00212-2004-09-07-UPD-NThe 38-year old man who died of Lassa fever in a New Jersey hospital traveled to the United States from Liberia via London. Further progress has been made in identifying passengers at risk of exposure to Lassa fever during travel on Continental Flight 29, which departed London Gatwick Airport on August 24 and arrived in Newark, N.J., at 3:20 pm on August 24.The plane was a Boeing 777-200, which has seats configured in groups of 3 with 9 seats and two aisles in each row. The case patient was seated in seat 21L, which is a window seat in economy class. Passengers seated within a six-foot radius of the case patient (i.e., passengers seated in seats F, J, K, L in rows 19-23) are considered at low risk for potential exposure, based on guidance outlined in the CDC HAN issued September 2, 2004.The airline has provided CDC the names of passengers who occupied seats 19 F-L, 20 F-L, 21 F-L, 22 F-L, and 23 F-L. CDC\u2019s Division of Global Migration and Quarantine is distributing this information to appropriate local and state health departments and national public health authorities, who in turn will advise passengers of their potential for exposure. In addition, these passengers will be advised to monitor their health for 21 days (i.e., the maximum incubation period) after their travel on Continental Flight 29. For airline passengers, this 21-day period ends September 14, 2004 and NOT September 18 as was incorrectly stated in the previous HAN. During this time, passengers should report a fever 101oF or greater to their local or state health department.Based upon currently available information and the configuration of the aircraft, only passengers seated in these 20 seat locations are considered to be at low risk of exposure. While no specific evaluation or monitoring is currently advised for persons seated in rows other than those listed above, any passenger who traveled on the implicated flight and who has concerns or develops a fever of 101oF or greater should seek medical evaluation and contact public health authorities.2004Lassa Fever, 2004VirusLassa viru

The application of Han Dynasty cultural elements to modern product design

Chinese Han Culture, as Chinese nation's "core culture", is the cultural symbol of Chinese nation, and played an important role in the history of Chinese cultural development, even in the history of world cultural development. Designing in the Han Dynasty, while inheriting Chinese traditional culture, but also having its unique style, are appreciated and respected by the people nowadays. In a modern society where the design is becoming more diversified, the innovative design based on traditional culture and art has its unique charm and vitality. This paper presented our recent research on the application of Han Dynasty cultural elements to modern product design, reflected the local design connotation of Han Dynasty cultural elements

A Model of Low-lying States in Strongly Interacting Electroweak Symmetry-Breaking Sector

It is proposed that, in a strongly-interacting electroweak sector, besides the Goldstone bosons, the coexistence of a scalar state ($H$) and vector resonances such as $A_1$ [$I^G(J^P)=1^-(1^+$)], $V$ [$1^+(1^-)$] and $\omega_H^{}$ [$0^-(1^-)$] is required by the proper Regge behavior of the forward scattering amplitudes. This is a consequence of the following well-motivated assumptions: (a). Adler-Weisberger-type sum rules and the superconvergence relations for scattering amplitudes hold in this strongly interacting sector; (b). the sum rules at $t=0$ are saturated by a minimal set of low-lying states with appropriate quantum numbers. It therefore suggests that a complete description should include all these resonances. These states may lead to distinctive experimental signatures at future colliders.Comment: revised version, to appear in Modern Physics Letters A; file also available via anonymous ftp at ftp://ucdhep.ucdavis.edu/han/sews/lowlying.p

The Effect of Binary Interactions in Infrared Passbands

We present the integrated J, H, K, L, M and N magnitudes and the colours involving infrared bands, for an extensive set of instantaneous-burst binary stellar populations (BSPs) by using evolutionary population synthesis (EPS). By comparing the results for BSPs WITH and WITHOUT binary interactions we show that the inclusion of binary interactions makes the magnitudes of populations larger (fainter) and the integrated colours smaller (bluer) for t > 1Gyr. Also, we compare our model magnitudes and colours with those of Bruzual & Charlot (2003, hereafter BC03) and Maraston (2005, hereafter M05). At last, we compare these model broad colours with Magellanic Clouds globular clusters (GCs) and Milky Way GCs. In (V-R)-[Fe/H] and (V-I)-[Fe/H] diagrams it seems that our models match the observations better than those of BC03 and M05.Comment: 2 page 3 figure