Signatures of supernova neutrino oscillations in the Earth mantle and core

The Earth matter effects on supernova (SN) neutrinos can be identified at a single detector through peaks in the Fourier transform of their ``inverse energy'' spectrum. The positions of these peaks are independent of the SN models and therefore the peaks can be used as a robust signature of the Earth matter effects, which in turn can distinguish between different neutrino mixing scenarios. Whereas only one genuine peak is observable when the neutrinos traverse only the Earth mantle, traversing also the core gives rise to multiple peaks. We calculate the strengths and positions of these peaks analytically and explore their features at a large scintillation detector as well as at a megaton water Cherenkov detector through Monte Carlo simulations. We propose a simple algorithm to identify the peaks in the actual data and quantify the chances of a peak identification as a function of the location of the SN in the sky.Comment: 17 pages, 9 figure

Testing Times for Supersymmetry: Looking Under the Lamp Post

We make a critical study of two highly-constrained models of supersymmetry --- the constrained minimal supersymmetric standard model (cMSSM), and the non-universal Higgs mass model (NUHM) --- in the light of the 125-126 GeV Higgs boson, the first observation of $B_s \to \mu\mu$ at the LHCb, and the updated $B \to \tau \nu$ branching ratio at BELLE. It turns out that these models are still allowed by the experimental data, even if we demand that there be a light stop with mass less than 1.5 TeV. The only significant effects of all these constraints are to push the mass of the light stop above $\sim 500$ GeV, and to prefer the universal trilinear coupling $A_0$ to be large and negative. We calculate the Higgs boson branching ratios to $WW, ZZ, \tau\tau$ and $\gamma\gamma$ in these models and show that improved experimental limits on these could put them to the most stringent experimental tests yet.Comment: Updated version consistent with recent data, a few references adde

Tree FCNC and non-unitarity of CKM matrix

We discuss possible signatures of the tree level FCNC, which results from the non-unitarity of CKM matrix. We first define the unitaity step-by-step, and possible test of the non-unitaity through the 4-value-KM parametrization. We, then, show how the phase angle of the unitary triangle would change in case of the vector-like down quark model. As another example of tree FCNC, we investigate the leptophobic $Z'$ model and its application to the recent $B_s$ mixing measurements.Comment: Talk given at Neutrino Masses and Mixings 2006 (NMM2006), Shizuoka, Japan (December 2006

Supernova pointing with low- and high-energy neutrino detectors

A future galactic SN can be located several hours before the optical explosion through the MeV-neutrino burst, exploiting the directionality of $\nu$-$e$-scattering in a water Cherenkov detector such as Super-Kamiokande. We study the statistical efficiency of different methods for extracting the SN direction and identify a simple approach that is nearly optimal, yet independent of the exact SN neutrino spectra. We use this method to quantify the increase in the pointing accuracy by the addition of gadolinium to water, which tags neutrons from the inverse beta decay background. We also study the dependence of the pointing accuracy on neutrino mixing scenarios and initial spectra. We find that in the ``worst case'' scenario the pointing accuracy is $8^\circ$ at 95% C.L. in the absence of tagging, which improves to $3^\circ$ with a tagging efficiency of 95%. At a megaton detector, this accuracy can be as good as $0.6^\circ$. A TeV-neutrino burst is also expected to be emitted contemporaneously with the SN optical explosion, which may locate the SN to within a few tenths of a degree at a future km$^2$ high-energy neutrino telescope. If the SN is not seen in the electromagnetic spectrum, locating it in the sky through neutrinos is crucial for identifying the Earth matter effects on SN neutrino oscillations.Comment: 13 pages, 7 figures, Revtex4 format. The final version to be published in Phys. Rev. D. A few points in the original text are clarifie

Supernova neutrino oscillations: what do we understand?

We summarize our current understanding of the neutrino flavor conversions inside a core collapse supernova, clarifying the important role played by the "collective effects" in determining flavor conversion probabilities. The potentially observable $\nu_e$ and $\bar{\nu}_e$ spectra may help us identify the neutrino mixing scenario, distinguish between primary flux models, and learn more about the supernova explosion.Comment: 6 pages, 1 eps figure, jpconf.cls used. Talk given at TAUP 2009, Rome, July 200

Supernova Neutrino Oscillations

Observing a high-statistics neutrino signal from a galactic supernova (SN) would allow one to test the standard delayed explosion scenario and may allow one to distinguish between the normal and inverted neutrino mass ordering due to the effects of flavor oscillations in the SN envelope. One may even observe a signature of SN shock-wave propagation in the detailed time-evolution of the neutrino spectra. A clear identification of flavor oscillation effects in a water Cherenkov detector probably requires a megatonne-class experiment.Comment: Proc. 129 Nobel Symposium "Neutrino Physics", 19-24 Aug 2004, Swede

Neutrino oscillations in low density medium

For the case of small matter effects: $V \ll \Delta m^2/2E$, where $V$ is the matter potential, we develop the perturbation theory using $\epsilon \equiv 2VE/\Delta m^2$ as the expansion parameter. We derive simple and physically transparent formulas for the oscillation probabilities in the lowest order in $\epsilon$ which are valid for arbitrary density profile. The formulas can be applied for propagation of the solar and supernova neutrinos in matter of the Earth, substantially simplifying numerical calculations. Using these formulas we study sensitivity of the oscillation effects to structures of the density profile situated at different distances from the detector $d$. We show that for the mass-to-flavor state transitions, {\it e.g.}, $\nu_2 \to \nu_e$, the sensitivity is suppressed for remote structures: $d > l_{\nu} E/\Delta E$, where $l_{\nu}$ is the oscillation length and $\Delta E/E$ is the energy resolution of detector.Comment: discussion simplified, clarifications adde

Physics potential of future supernova neutrino observations

We point out possible features of neutrino spectra from a future galactic core collapse supernova that will enhance our understanding of neutrino mixing as well as supernova astrophysics. We describe the neutrino flavor conversions inside the star, emphasizing the role of "collective effects" that has been appreciated and understood only very recently. These collective effects change the traditional predictions of flavor conversion substantially, and enable the identification of neutrino mixing scenarios through signatures like Earth matter effects.Comment: 8 pages, uses jpconf.cls. Talk given at Neutrino 2008, Christchurch, NZ. Some entries in Table 2 have been correcte

Nonleptonic two-body charmless B decays involving a tensor meson in ISGW2 model

Nonleptonic charmless B decays into a pseudoscalar (P) or a vector (V) meson accompanying a tensor (T) meson are re-analyzed. We scrutinize the hadronic uncertainties and ambiguities of the form factors which appear in the literature. The Isgur-Scora-Grinstein-Wise updated model (ISGW2) is adopted to evaluate the relevant hadronic matrix elements. We calculate the branching ratios and CP asymmetries for various $B\to P(V)T$ decay processes. With the ISGW2 model, the branching ratios are enhanced by about an order of magnitude compared to the previous estimates. We show that the ratios \calB(B\to VT)/\calB(B\to PT) for some strangeness-changing processes are very sensitive to the CKM angle $\gamma$ ($\phi_3$).Comment: 23 pages, REVTEX; minor clarifications included; to appear in Phys. Rev.

Weak Phase γ\gamma From Ratio of B→KπB \to K \pi Rates

The ratio of partial decay rates for charged and neutral $B$ mesons to $K \pi$ final states provides information on the weak phase $\gamma \equiv {\rm Arg} (V_{ub}^*)$ when augmented with information on the CP-violating asymmetry in the $K^\pm \pi^\mp$ mode. The requirements for a useful determination of $\gamma$ are examined in the light of present information about the decays $B^0 \to K^+ \pi^-$, $B^+ \to K^0 \pi^+$, and the corresponding charge-conjugate modes. The effects of electroweak penguins and rescattering corrections are noted, and proposals are made for estimating and measuring their importance.Comment: 16 pages, latex, 3 figures, revised version sent to Phys. Rev.