2,120 research outputs found
Generational Mass Splitting of Neutrinos in High Temperature Gauge Theory
We calculate the generational mass splitting of neutrinos in high temperature
gauge theory when the temperature
is above GeV and the gauge symmetry is restored. We consider the case of
neutrinos that are massless at tree level as well as the case of neutrinos with
tree-level mass and large mixing.Comment: 12 Pages, JHU-TIPAC-940008/INFNCA-TH-94-
Performance of RF MEMS switches at low temperatures
The actuation voltage of microelectromechanical system (MEMS) \ud
metal switches was investigated at temperatures ranging from 10 to 290 K. The investigation shows a 50% increase in the actuation voltage at low temperature. A comparison has been made using a published model and showed similar increment of actuation voltage at low temperature
Gravitational Effects on the Neutrino Oscillation
The propagation of neutrinos in a gravitational field is studied. A method of
calculating a covariant quantum-mechanical phase in a curved space-time is
presented. The result is used to calculate gravitational effects on the
neutrino oscillation in the presence of a gravitational field. We restrict our
discussion to the case of the Schwartzschild metric. Specifically, the cases of
the radial propagation and the non-radial propagation are considered. A
possible application to gravitational lensing of neutrinos is also suggested.Comment: 15 pages, RevTex, No figures. Minor modifications and some typos
correcte
Rare radiative exclusive B decays in soft-collinear effective theory
We consider rare radiative B decays such as B -> K^* gamma or B -> rho gamma
in soft-collinear effective theory, and show that the decay amplitudes are
factorized to all orders in alpha_s and at leading order in Lambda/m_b.By
employing two-step matching, we classify the operators for radiative B decays
in powers of a small parameter lambda(~ \sqrt{Lambda/m_b}) and obtain the
relevant operators to order lambda in SCET_I. These operators are constructed
with or without spectator quarks including the four-quark operators
contributing to annihilation and W-exchange channels. And we employ SCET_II
where the small parameter becomes of order Lambda/m_b, and evolve the operators
in order to compute the decay amplitudes for rare radiative decays in
soft-collinear effective theory. We show explictly that the contributions from
the annihilation channels and the W-exchange channels vanish at leading order
in SCET. We present the factorized result for the decay amplitudes in rare
radiative B decays at leading order in SCET, and at next-to-leading order in
alpha_s.Comment: v2: 31 pages, 11 figures. An appendix is added about the quark mass
effects on radiative B decay
A scale-dependent cosmology for the inhomogeneous Universe
A scale-dependent cosmology is proposed in which the Robertson-Walker metric
and the Einstein equation are modified in such a way that , and
the age of the Universe all become scale-dependent. Its implications on the
observational cosmology are discussed.Comment: 7 pages, in RevTex. To be appeared in TAUP '9
EP-1260: Prognostic factors in hepatoma patients treated with radiotherapy for lymph node metastasis
Do the Age of the Universe and the Hubble Constant Depend on What Scale One Observes Them?
The apparent cosmological conflict between the age of the Universe, predicted
in the standard Friedman cosmology by using the recent measurement of the
larger Hubble constant from a direct calibration of the distance to the Virgo
galaxy cluster, and the ages of the oldest stars and globular clusters is
resolved by invoking the scale dependence of cosmological quantities, including
the age of the Universe. The distance dependence or the running of cosmological
quantities is motivated by the asymptotically-free higher- derivative quantum
gravity. The running can also be derived by ``properly" modifying the Friedman
equations. This property can also provide partial explanation of the apparent
disagreement between the two recent measurements of the Hubble constant using
NGC 4571 at 15 Mpc and NGC 5253 at 4 Mpc.Comment: Revtex file, 9 pages (no figures
Magnetic properties of neutrinos in high temperature SU(2)XU(1) gauge theory
We calculate the finite temperature self-energy for neutrinos in the presence
of a constant magnetic field in a medium in the unbroken
model. We obtain the exact dispersion relation for such neutrinos and find that
the thermal effective mass is modified by the magnetic field. We also find a
simple analytic expression for the dispersion relation and obtain the index of
refraction for large neutrino momentum.Comment: 13 pp, RevTeX, no figure
Collinear effective theory at subleading order and its application to heavy-light currents
We consider a collinear effective theory of highly energetic quarks with
energy E, interacting with collinear and soft gluons by integrating out
collinear degrees of freedom to subleading order. The collinear effective
theory offers a systematic expansion in power series of a small parameter
lambda ~ p_{\perp}/E, where p_{\perp} is the transverse momentum of a collinear
particle. We construct the effective Lagrangian to first order in ,
and discuss its features including additional symmetries such as collinear
gauge invariance and reparameterization invariance. Heavy-light currents can be
matched from the full theory onto the operators in the collinear effective
theory at one loop and to order lambda. We obtain heavy-light current operators
in the effective theory, calculate their Wilson coefficients at this order, and
the renormalization group equations for the Wilson coefficients are solved. As
an application, we calculate the form factors for decays of B mesons to light
energetic mesons to order lambda and at leading-logarithmic order in alpha_s.Comment: 29 pages, 5 figures, revised versio
- …