Effect of the smaller mass-squared difference for the long base-line neutrino experiments

Usually, neutrino oscillation experiments are analyzed within the two-flavor framework which is governed by 1 mass-squared difference and 1 mixing angle. But there are 6 parameters,2 mass-squared differences, 3 mixing angles, and 1 CP phase within the three-flavor framework.In this article,we estimate the effect from the smaller mass-squared difference,the other mixing angles, and the CP phase, which we call three-flavor effect, for the determination of the mass-squared difference and the mixing angle from the nu_mu's survival and transition probability with the two-flavor analysis.It is found that the mass-squared difference from the two-flavor analysis is slightly shifted from the larger mass-squared difference by the three-flavor effect.The order of magnitude of the three-flavor effect for the mass-squared difference is comparable with that of the expected error for the mass-squared difference of the two-flavor analysis in the future long base-line neutrino oscillation experiments.The CP phase dependence of the nu_mu to nu_etransition probability is also shown.Comment: 13 pages, no figure new reference added, correct typos, Accepted by Progress of Theoretical Physic

Re-evaluation of the T2KK physics potential with simulations including backgrounds

The Tokai-to-Kamioka-and-Korea (T2KK) neutrino oscillation experiment under examination can have a high sensitivity to determine the neutrino mass hierarchy for a combination of relatively large (\sim 3.0^circ) off-axis angle beam at Super-Kamiokande (SK) and small (\sim 0.5^circ) off-axis angle at L \sim 1,000km in Korea. We elaborate previous studies by taking into account smearing of reconstructed neutrino energy due to finite resolution of electron or muon energies, nuclear Fermi motion and resonance production, as well as the neutral current \pi^0 production background to the nu_mu to nu_e oscillation signal. It is found that the mass hierarchy pattern can still be determined at 3sigma level if sin^22thata_rct \quiv 4|U_{e3}|^2(1-|U_{e3}|^2) \gsim 0.08(0.09) when the hierarchy is normal (inverted) with 5 \times10^{21} POT exposure, or 5 years of the T2K experiment, if a 100kton water cherenkov detector is placed in Korea. The \pi^0 backgrounds deteriorate the capability of the mass hierarchy determination, whereas the events from nuclear resonance productions contribute positively to the hierarchy discrimination power. We also find that the \pi^0 backgrounds seriously affect the CP phase measurement. Although \delta_mns can still be constrained with an accuracy of \sim \pm 45^circ (\pm 60^circ) at 1sigma level for the normal (inverted) hierarchy with the above exposure if sin^22theta_rct \gsim 0.04, CP violation can no longer be established at 3sigma level even for delta_mns=\pm 90^circ and sin^22theta_rct=0.1. About four times higher exposure will be needed to measure delta_mns with \pm 30^circ accuracy.Comment: 46 pages, 13 figure

Solving the neutrino parameter degeneracy by measuring the T2K off-axis beam in Korea

The T2K neutrino oscillation experiment will start in 2009. In this experiment the center of the neutrino beam from J-PARC at Tokai village will go through underground beneath Super-Kamiokande, reach the sea level east of Korean shore, and an off-axis beam at $0.5^{\circ}$ to $1.0^{\circ}$ can be observed in Korea. We study physics impacts of putting a 100 kt-level Water \cerenkov detector in Korea during the T2K experimental period. For a combination of the $3^{\circ}$ off-axis beam at SK with baseline length L = 295 km and the $0.5^{\circ}$ off-axis beam in the east coast of Korea at L = 1000 km, we find that the neutrino mass hierarchy (the sign of $m^2_{3} - m^2_1$) can be resolved and the CP phase of the MNS unitary matrix can be constrained uniquely at 3-$\sigma$ level when \sin^2 2\theta_{\rm rct} $\ge 0.06$

The structure and the evolution of essential patents for standards: Lessons from three IT standards

This paper examines the structure and the evolution of the patents declared as essential for three major technical standards in information technology (MPEG2, DVD and W-CDMA). These standards have many essential patents, which are owned by many firms with different interests. Many patents have been applied even after the standard was set. We analyze three important reasons for why the essential patents are many and increase over time: they cover a number of different technology fields, there exist R&D competition even in a narrowly defined technology field and a firm can expand its patent portfolio by using continuations and other practices based on the priority dates of its earlier filed patent applications in the USA. Around 40% of the essential US patents for MPEG2 and DVD standards have been obtained by using these applications. However, our empirical analysis suggests that a firm with pioneering patents does not obtain more essential patents, using these practices.standard, essential patent, continuations

Revisiting T2KK and T2KO physics potential and νμ\nu_\mu - νˉμ\bar{\nu}_\mu beam ratio

We revisit the sensitivity study of the Tokai-to-Kamioka-and-Korea (T2KK) and Tokai-to-Kamioka-and-Oki (T2KO) proposals where a water Cerenkov detector with the 100 kton fiducial volume is placed in Korea ($L = 1000$ km) and Oki island ($L = 653$ km) in Japan, respectively, in addition to the Super-Kamiokande for determination of the neutrino mass hierarchy and leptonic CP phase ($\delta_{CP}$). We systematically study the running ratio of the $\nu_\mu$ and $\bar{\nu}_\mu$ focusing beams with dedicated background estimation for the $\nu_e$ appearance and $\nu_\mu$ disappearance signals, especially improving treatment of the neutral current $\pi^0$ backgrounds. Using a $\nu_\mu$ - $\bar{\nu}_\mu$ beam ratio between 3 : 2 and 2.5 : 2.5 (in unit of $10^{21}$POT with the proton energy of 40 GeV), the mass hierarchy determination with the median sensitivity of 3 - 5 $\sigma$ by the T2KK and 1 - 4 $\sigma$ by the T2KO experiment are expected when $\sin^2\theta_{23} = 0.5$, depending on the mass hierarchy pattern and CP phase. These sensitivities are enhanced (reduced) by $30\%$ - $40\%$ in $\Delta \chi^2$ when $\sin^2\theta_{23} = 0.6\, (0.4)$. The CP phase is measured with the uncertainty of $20^\circ$ - $50^\circ$ by the T2KK and T2KO using the $\nu_\mu$ - $\bar{\nu}_\mu$ focusing beam ratio between 3.5 : 1.5 and 1.5 : 3.5. These findings indicate that inclusion of the $\bar{\nu}_\mu$ focusing beam improves the sensitivities of the T2KK and T2KO experiments to both the mass hierarchy determination and leptonic CP phase measurement simultaneously with the preferred beam ratio being between 3 : 2 - 2.5 : 2.5 ($\times 10^{21}$POT).Comment: 33 pages, 16 figures, 5 table