41 research outputs found
On in situ Determination of Earth Matter Density in Neutrino Factory
We point out that an accurate in situ determination of the earth matter
density \rho is possible in neutrino factory by placing a detector at the magic
baseline, L = \sqrt{2} \pi / G_{F} N_{e} where N_{e} denotes electron number
density. The accuracy of matter density determination is excellent in a region
of relatively large theta_{13} with fractional uncertainty \delta \rho / \rho
of about 0.43%, 1.3%, and \lsim 3% at 1 sigma CL at sin^2 2theta_{13}=0.1,
10^{-2}, and 3 x 10^{-3}, respectively. At smaller theta_{13} the uncertainty
depends upon the CP phase delta, but it remains small, 3%-7% in more than 3/4
of the entire region of delta at sin^2 2theta_{13} = 10^{-4}. The results would
allow us to solve the problem of obscured CP violation due to the uncertainty
of earth matter density in a wide range of theta_{13} and delta. It may provide
a test for the geophysical model of the earth, or it may serve as a method for
stringent test of the MSW theory of neutrino propagation in matter once an
accurate geophysical estimation of the matter density is available.Comment: 21 pages, 4 figures, version to appear in PR
Testing CPT Symmetry with Supernova Neutrinos
Diagnosing core of supernova requires favor-dependent reconstruction of three
species of neutrino spectra, \nu_e, \bar{\nu}_{e} and \nu_x (a collective
notation for \nu_{\mu}, \bar{\nu}_{\mu}, \nu_{\tau}, and \bar{\nu}_{\tau}). We
point out that, assuming the information available, CPT symmetry can be tested
with supernova neutrinos. We classify all possible level crossing patterns of
neutrinos and antineutrinos into six cases and show that half of them contains
only the CPT violating mass and mixing patterns. We discuss how additional
informations from terrestrial experiments help identifying CPT violation by
narrowing down the possible flux patterns. Although the method may not be good
at precision test, it is particularly suited to uncover gross violation of CPT
such as different mass patterns of neutrinos and antineutrinos. The power of
the method is due to the nature of level crossing in supernova which results in
the sensitivity to neutrino mass hierarchy and to the unique characteristics of
in situ preparation of both \nu and \bar{\nu} beams. Implications of our
discussion to the conventional analyses with CPT conservation are also briefly
mentioned.Comment: 24 pages, 4 figures, discussion added on narrowing down flux patterns
by terrestrial measuremen
Probing Non-Standard Neutrino Interactions with Neutrino Factories
We discuss the sensitivity reach of a neutrino factory measurement to
non-standard neutrino interactions (NSI), which may exist as a low-energy
manifestation of physics beyond the Standard Model. We use the muon appearance
mode \nu_e --> \nu_\mu and consider two detectors, one at 3000 km and the other
at 7000 km.
Assuming the effects of NSI at the production and the detection are
negligible, we discuss the sensitivities to NSI and the simultaneous
determination of \theta_{13} and \delta by examining the effects in the
neutrino propagation of various systems in which two NSI parameters
\epsilon_{\alpha \beta} are switched on. The sensitivities to off-diagonal
\epsilon's are found to be excellent up to small values of \theta_{13}.
We demonstrate that the two-detector setting is powerful enough to resolve
the \theta_{13}-NSI confusion problem. We believe that the results obtained in
this paper open the door to the possibility of using neutrino factory as a
discovery machine for NSI while keeping its primary function of performing
precision measurements of the lepton mixing parameters.Comment: 47 pages, 22 figures. Color version of Figs. 18, 19 and 22 can be
found in the article published in JHE
Perturbation Theory of Neutrino Oscillation with Nonstandard Neutrino Interactions
We discuss various physics aspects of neutrino oscillation with non-standard
interactions (NSI). We formulate a perturbative framework by taking \Delta
m^2_{21} / \Delta m^2_{31}, s_{13}, and the NSI elements \epsilon_{\alpha
\beta} (\alpha, \beta = e, \mu, \tau) as small expansion parameters of the same
order \epsilon. Within the \epsilon perturbation theory we obtain the S matrix
elements and the neutrino oscillation probability formula to second order
(third order in \nu_e related channels) in \epsilon. The formula allows us to
estimate size of the contribution of any particular NSI element
\epsilon_{\alpha beta} to the oscillation probability in arbitrary channels,
and gives a global bird-eye view of the neutrino oscillation phenomena with
NSI. Based on the second-order formula we discuss how all the conventional
lepton mixing as well as NSI parameters can be determined. Our results shows
that while \theta_{13}, \delta, and the NSI elements in \nu_e sector can in
principle be determined, complete measurement of the NSI parameters in the
\nu_\mu - \nu_\tau sector is not possible by the rate only analysis. The
discussion for parameter determination and the analysis based on the matter
perturbation theory indicate that the parameter degeneracy prevails with the
NSI parameters. In addition, a new solar-atmospheric variable exchange
degeneracy is found. Some general properties of neutrino oscillation with and
without NSI are also illuminated.Comment: manuscript restructured, discussion of new type of parameter
degeneracy added. 47 page
Recoilless Resonant Absorption of Monochromatic Neutrino Beam for Measuring Delta m^2_{31} and theta_{13}
We discuss, in the context of precision measurement of Delta m^2_{31} and
theta_{13}, physics capabilities enabled by the recoilless resonant absorption
of monochromatic antineutrino beam enhanced by the M\"ossbauer effect recently
proposed by Raghavan. Under the assumption of small relative systematic error
of a few tenth of percent level between measurement at different detector
locations, we give analytical and numerical estimates of the sensitivities to
Delta m^2_{31} and sin^2 2theta_{13}. The accuracies of determination of them
are enormous; The fractional uncertainty in Delta m^2_{31} achievable by 10
point measurement is 0.6% (2.4%) for sin^2 2theta_{13} = 0.05, and the
uncertainty of sin^2 2theta_{13} is 0.002 (0.008) both at 1 sigma CL with the
optimistic (pessimistic) assumption of systematic error of 0.2% (1%). The
former opens a new possibility of determining the neutrino mass hierarchy by
comparing the measured value of Delta m^2_{31} with the one by accelerator
experiments, while the latter will help resolving the theta_{23} octant
degeneracy.Comment: 23 pages, 3 figures, version to appear in New Journal of Physic
Broad-Spectrum Matrix Metalloproteinase Inhibition Curbs Inflammation and Liver Injury but Aggravates Experimental Liver Fibrosis in Mice
Background Liver fibrosis is characterized by excessive synthesis of extracellular matrix proteins, which prevails over their enzymatic degradation, primarily by matrix metalloproteinases (MMPs). The effect of pharmacological MMP inhibition on fibrogenesis, however, is largely unexplored. Inflammation is considered a prerequisite and important co-contributor to fibrosis and is, in part, mediated by tumor necrosis factor (TNF)-α-converting enzyme (TACE). We hypothesized that treatment with a broad-spectrum MMP and TACE-inhibitor (Marimastat) would ameliorate injury and inflammation, leading to decreased fibrogenesis during repeated hepatotoxin-induced liver injury.Methodology/Principal Findings Liver fibrosis was induced in mice by repeated carbon tetrachloride (CCl4) administration, during which the mice received either Marimastat or vehicle twice daily. A single dose of CCl4was administered to investigate acute liver injury in mice pretreated with Marimastat, mice deficient in Mmp9, or mice deficient in both TNF-α receptors. Liver injury was quantified by alanine aminotransferase (ALT) levels and confirmed by histology. Hepatic collagen was determined as hydroxyproline, and expression of fibrogenesis and fibrolysis-related transcripts was determined by quantitative reverse-transcription polymerase chain reaction. Marimastat-treated animals demonstrated significantly attenuated liver injury and inflammation but a 25% increase in collagen deposition. Transcripts related to fibrogenesis were significantly less upregulated compared to vehicle-treated animals, while MMP expression and activity analysis revealed efficient pharmacologic MMP-inhibition and decreased fibrolysis following Marimastat treatment. Marimastat pre-treatment significantly attenuated liver injury following acute CCl4-administration, whereas Mmp9 deficient animals demonstrated no protection. Mice deficient in both TNF-α receptors exhibited an 80% reduction of serum ALT, confirming the hepatoprotective effects of Marimastat via the TNF-signaling pathway.Conclusions/Significance Inhibition of MMP and TACE activity with Marimastat during chronic CCl4administration counterbalanced any beneficial anti-inflammatory effect, resulting in a positive balance of collagen deposition. Since effective inhibition of MMPs accelerates fibrosis progression, MMP inhibitors should be used with caution in patients with chronic liver diseases