摘要:

I review the topic of relic neutrino asymmetry generation through active-sterile neutrino and antineutrino oscillations in the early universe. Applications to (i) the suppression of sterile neutrino production, and (ii) the primordial Helium abundance are briefly presented. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328886

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We review the use of Type Ia supernovae for cosmological distance determinations. Low-redshift SNe Ia(z≲0.1)demonstrate that the Hubble expansion is linear, thatH0=65±2(statistical) km−1Mpc−1, and that the properties of dust in other galaxies are similar to those of dust in the Milky Way. We find that the light curves of high-redshift(z=0.3–1)SNe Ia are stretched in a manner consistent with the expansion of space; similarly, their spectra exhibit slower temporal evolution (by a factor of1+z) than those of nearby SNe Ia. The luminosity distances of our first set of 16 high-redshift SNe Ia are, on average, 10–15&percent; farther than expected in a low mass-density(&OHgr;M=0.2)universe without a cosmological constant. Preliminary analysis of our second set of 9 SNe Ia is consistent with this. Our work supports models with positive cosmological constant and a current acceleration of the expansion. We address the main potential sources of systematic error; at present, none of them appears to reconcile the data with&OHgr;&Lgr;=0andq0⩾0.The dynamical age of the Universe is estimated to be14.2±1.7&hthinsp;Gyr,consistent with the ages of globular star clusters. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328887

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We review the latest results and prospects for pulsar astronomy in the new millennium. Some of the most exciting discoveries and their impact on our understanding of radio pulsars are discussed as well as speculations for the future. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328888

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

A ∼2-meter satellite telescope with a 1-square-degree optical imager, a small near-IR imager, and a three-arm near-UV-to-near-IR spectrograph can discover over 2000 Type Ia supernovae in a year at redshifts betweenz=0.1and 1.7, and follow them with high-signal-to-noise calibrated light-curves and spectra. The resulting data set can determine the cosmological parameters with precision: mass density&OHgr;Mto ±0.02, vacuum energy density&OHgr;&Lgr;to ±0.05, and curvature&OHgr;kto ±0.06. The data set can test the nature of the “dark energy” that is apparently accelerating the expansion of the universe. In particular, a cosmological constant dark energy can be differentiated from alternatives including a range of “quintessence” dynamical scalar-field models, by measuring the ratio of the dark energy’s pressure to its density to ±0.05 over a range of redshifts. The large numbers of supernovae across a wide range of redshifts are necessary but not sufficient to accomplish these goals; the controls for systematic uncertainties are primary drivers of the design of this space-based experiment. These systematic and statistical controls cannot be obtained with other ground-based and/or space-based telescopes, either currently in construction or in planning stages. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328889

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Some past, present, and future aspects of CP violation are reviewed. The discrete symmetries C, P, and T are introduced with an example drawn from Maxwell’s Equations. The history of the discovery of CP violation in the kaon system is described briefly, and brought up-to-date with a review of recent results on kaon decays. The candidate theory of CP violation, based on phases in the Cabibbo-Kobayashi-Maskawa (CKM) matrix, will be tested by studies ofBmesons, both in decays to CP eigenstates and in “direct” decays; we will soon learn a great deal more about whether the CKM picture is self-consistent. Future measurements are noted and some brief remarks are made about the “other” manifestation of CP violation, the baryon asymmetry of the Universe. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328890

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The CPLEAR experiment at CERN has directly studied matter and antimatter symmetries via the measurement of the time evolution ofK0andK¯0.The CPT violation parameterRe(&dgr;)was directly measured with a precision of a few10−4whileIm(&dgr;)is determined from the Bell-Steinberger relation, with a precision of10−5.The mass and decay-width equality between theK0andK¯0were tested down to the level of10−18&hthinsp;GeV.©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328891

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We give an account of various possible measurements in B physics for the collider experiments, CDF andDO&slash;,in the coming Tevatron Run II at Fermilab. This includes the measurements ofsin(2&bgr;)and other angles in the unitarity triangle related to the CKM matrix, which may lead to observation of CP violation outside the kaon system. Measurements of mass and lifetime differences, especially forBs,will be particularly interesting at Tevatron as this probably would not be studied in the present B factories. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328892

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The NuTeV Experiment at Fermilab has searched for indications of physics beyond the standard model using indirect and direct search methods. The indirect method compares the NuTeV measurement ofsin2&hthinsp;&thgr;Wto the world measurement for this parameter. The direct measurement searches for decays of exotic neutral particles in a light mass, instrumented region upstream of the NuTeV calorimeter. No evidence for new physics has been observed. Therefore, NuTeV has placed constraints on extensions to the Standard Model which include certainZ′’s, neutral heavy leptons and the particle responsible for the Karmen Timing Anomaly. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328893

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The status of the searches for supersymmetry using the LEP data taken in 1999 and earlier and their consequence will be given. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328894

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We give the summary of the bounds on extra dimensions obtained from LEP running at energy above Z-pole. We present limits on “effective” Planck massMDand radius of extra dimensions from direct graviton production, limits on cut-off parameterMsfrom virtual graviton exchange contribution and limits on compactification scaleMcfrom electroweak observables and Bhabha scattering. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328895

出版商:AIP    

年代:1900

数据来源: AIP