3,670 research outputs found
Updated Values of Running Quark and Lepton Masses
Reliable values of quark and lepton masses are important for model building
at a fundamental energy scale, such as the Fermi scale M_Z \approx 91.2 GeV and
the would-be GUT scale \Lambda_GUT \sim 2 \times 10^16 GeV. Using the latest
data given by the Particle Data Group, we update the running quark and
charged-lepton masses at a number of interesting energy scales below and above
M_Z. In particular, we take into account the possible new physics scale (\mu
\sim 1 TeV) to be explored by the LHC and the typical seesaw scales (\mu \sim
10^9 GeV and \mu \sim 10^12 GeV) which might be relevant to the generation of
neutrino masses. For illustration, the running masses of three light Majorana
neutrinos are also calculated. Our up-to-date table of running fermion masses
are expected to be very useful for the study of flavor dynamics at various
energy scales.Comment: 23 pages, 6 tables, 2 figures; version published in PR
Neutrino Masses, Lepton Flavor Mixing and Leptogenesis in the Minimal Seesaw Model
We present a review of neutrino phenomenology in the minimal seesaw model
(MSM), an economical and intriguing extension of the Standard Model with only
two heavy right-handed Majorana neutrinos. Given current neutrino oscillation
data, the MSM can predict the neutrino mass spectrum and constrain the
effective masses of the tritium beta decay and the neutrinoless double-beta
decay. We outline five distinct schemes to parameterize the neutrino
Yukawa-coupling matrix of the MSM. The lepton flavor mixing and baryogenesis
via leptogenesis are investigated in some detail by taking account of possible
texture zeros of the Dirac neutrino mass matrix. We derive an upper bound on
the CP-violating asymmetry in the decay of the lighter right-handed Majorana
neutrino. The effects of the renormalization-group evolution on the neutrino
mixing parameters are analyzed, and the correlation between the CP-violating
phenomena at low and high energies is highlighted. We show that the observed
matter-antimatter asymmetry of the Universe can naturally be interpreted
through the resonant leptogenesis mechanism at the TeV scale. The
lepton-flavor-violating rare decays, such as , are also
discussed in the supersymmetric extension of the MSM.Comment: 50 pages, 22 EPS figures, macro file ws-ijmpe.cls included, accepted
for publication in Int. J. Mod. Phys.
Initiation and Early Kinematic Evolution of Solar Eruptions
We investigate the initiation and early evolution of 12 solar eruptions,
including six active region hot channel and six quiescent filament eruptions,
which were well observed by the \textsl{Solar Dynamics Observatory}, as well as
by the \textsl{Solar TErrestrial RElations Observatory} for the latter. The
sample includes one failed eruption and 11 coronal mass ejections, with
velocities ranging from 493 to 2140~km~s. A detailed analysis of the
eruption kinematics yields the following main results. (1) The early evolution
of all events consists of a slow-rise phase followed by a main-acceleration
phase, the height-time profiles of which differ markedly and can be best fit,
respectively, by a linear and an exponential function. This indicates that
different physical processes dominate in these phases, which is at variance
with models that involve a single process. (2) The kinematic evolution of the
eruptions tends to be synchronized with the flare light curve in both phases.
The synchronization is often but not always close. A delayed onset of the
impulsive flare phase is found in the majority of the filament eruptions (5 out
of 6). This delay, and its trend to be larger for slower eruptions, favor ideal
MHD instability models. (3) The average decay index at the onset heights of the
main acceleration is close to the threshold of the torus instability for both
groups of events (although based on a tentative coronal field model for the hot
channels), suggesting that this instability initiates and possibly drives the
main acceleration.Comment: Accepted for publication in ApJ; 24 pages, 12 figures, 3 table
The components of empirical multifractality in financial returns
We perform a systematic investigation on the components of the empirical
multifractality of financial returns using the daily data of Dow Jones
Industrial Average from 26 May 1896 to 27 April 2007 as an example. The
temporal structure and fat-tailed distribution of the returns are considered as
possible influence factors. The multifractal spectrum of the original return
series is compared with those of four kinds of surrogate data: (1) shuffled
data that contain no temporal correlation but have the same distribution, (2)
surrogate data in which any nonlinear correlation is removed but the
distribution and linear correlation are preserved, (3) surrogate data in which
large positive and negative returns are replaced with small values, and (4)
surrogate data generated from alternative fat-tailed distributions with the
temporal correlation preserved. We find that all these factors have influence
on the multifractal spectrum. We also find that the temporal structure (linear
or nonlinear) has minor impact on the singularity width of the
multifractal spectrum while the fat tails have major impact on ,
which confirms the earlier results. In addition, the linear correlation is
found to have only a horizontal translation effect on the multifractal spectrum
in which the distance is approximately equal to the difference between its DFA
scaling exponent and 0.5. Our method can also be applied to other financial or
physical variables and other multifractal formalisms.Comment: 6 epl page
Gravitating Global k-monopole
A gravitating global k-monopole produces a tiny gravitational field outside
the core in addition to a solid angular deficit in the k-field theory. As a new
feature, the gravitational field can be attractive or repulsive depending on
the non-canonical kinetic term.Comment: 9 pages, 2 figures, references added, typos corrected, accepted by
Class. Quantum Gra
Two-zero Textures of the Majorana Neutrino Mass Matrix and Current Experimental Tests
In view of the latest T2K and MINOS neutrino oscillation data which hint at a
relatively large theta_13, we perform a systematic study of the Majorana
neutrino mass matrix M_nu with two independent texture zeros. We show that
three neutrino masses (m_1, m_2, m_3) and three CP-violating phases (delta,
rho, sigma) can fully be determined from two neutrino mass-squared differences
(delta m^2, Delta m^2) and three flavor mixing angles (theta_12, theta_23,
theta_13). We find that seven patterns of M_nu (i.e., A_{1,2}, B_{1,2,3,4} and
C) are compatible with current experimental data at the 3-sigma level, but the
parameter space of each pattern is more strictly constrained than before. We
demonstrate that the texture zeros of M_nu are stable against the one-loop
quantum corrections, and there exists a permutation symmetry between Patterns
A_1 and A_2, B_1 and B_2 or B_3 and B_4. Phenomenological implications of M_nu
on the neutrinoless double-beta decay and leptonic CP violation are discussed,
and a realization of those texture zeros by means of the Z_n flavor symmetries
is illustrated.Comment: 41 pages, including 4 tables and 14 figures, more discussions added,
to appear in JHE
Impacts of the Higgs mass on vacuum stability, running fermion masses and two-body Higgs decays
The latest results of the ATLAS and CMS experiments indicate 116 GeV \lesssim
M_H \lesssim 131 GeV and 115 GeV \lesssim M_H \lesssim 127 GeV, respectively,
for the mass of the Higgs boson in the standard model (SM) at the 95%
confidence level. In particular, both experiments point to a preferred narrow
mass range M_H \simeq (124 ... 126) GeV. We examine the impact of this
preliminary result of M_H on the SM vacuum stability by using the two-loop
renormalization-group equations (RGEs), and arrive at the cutoff scale
\Lambda_VS \sim 4 \times 10^{12} GeV (for M_H = 125 GeV, M_t = 172.9 GeV and
\alpha_s(M_Z) = 0.1184) where the absolute stability of the SM vacuum is lost
and some kind of new physics might take effect. We update the values of running
lepton and quark masses at some typical energy scales, including the ones
characterized by M_H, 1 TeV and \Lambda_VS, with the help of the two-loop RGEs.
The branching ratios of some important two-body Higgs decay modes, such as H
\to b\bar{b}, H \to \tau^+ \tau^-, H\to \gamma\gamma, H\to W^+ W^- and H \to Z
Z, are also recalculated by inputting the values of relevant particle masses at
M_H.Comment: RevTex 14 pages, 4 figures; the treatment of vacuum stability
improved, references update
An improvement of isochronous mass spectrometry: Velocity measurements using two time-of-flight detectors
Isochronous mass spectrometry (IMS) in storage rings is a powerful tool for
mass measurements of exotic nuclei with very short half-lives down to several
tens of microseconds, using a multicomponent secondary beam separated in-flight
without cooling. However, the inevitable momentum spread of secondary ions
limits the precision of nuclear masses determined by using IMS. Therefore, the
momentum measurement in addition to the revolution period of stored ions is
crucial to reduce the influence of the momentum spread on the standard
deviation of the revolution period, which would lead to a much improved mass
resolving power of IMS. One of the proposals to upgrade IMS is that the
velocity of secondary ions could be directly measured by using two
time-of-flight (double TOF) detectors installed in a straight section of a
storage ring. In this paper, we outline the principle of IMS with double TOF
detectors and the method to correct the momentum spread of stored ions.Comment: Accepted by Nuclear Inst. and Methods in Physics Research,
Protection induced by simultaneous subcutaneous and endobronchial vaccination with BCG/BCG and BCG/adenovirus expressing antigen 85A against Mycobacterium bovis in cattle
The incidence of bovine tuberculosis (bTB) in the GB has been increasing since the 1980s. Immunisation, alongside current control measures, has been proposed as a sustainable measure to control bTB. Immunisation with Mycobacterium bovis bacillus Calmette-Guerin (BCG) has been shown to protect against bTB. Furthermore, much experimental data indicates that pulmonary local immunity is important for protection against respiratory infections including Mycobacterium tuberculosis and that pulmonary immunisation is highly effective. Here, we evaluated protection against M. bovis, the main causative agent of bTB, conferred by BCG delivered subcutaneously, endobronchially or by the new strategy of simultaneous immunisation by both routes. We also tested simultaneous subcutaneous immunisation with BCG and endobronchial delivery of a recombinant type 5 adenovirus expressing mycobacterial antigen 85A. There was significantly reduced visible pathology in animals receiving the simultaneous BCG/BCG or BCG/Ad85 treatment compared to naïve controls. Furthermore, there were significantly fewer advanced microscopic granulomata in animals receiving BCG/Ad85A compared to naive controls. Thus, combining local and systemic immunisation limits the development of pathology, which in turn could decrease bTB transmission
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