Specific heat evidence for two-gap superconductivity in ternary-iron silicide Lu2_{2}Fe3_{3}Si5_{5}

We report low-temperature specific heat studies on single-crystalline ternary-iron silicide superconductor Lu$_{2}$Fe$_{3}$Si$_{5}$ with$T_c$ = 6.1 K down to $\sim T_c/20$. We confirm a reduced normalized jump in specific heat at $T_c$, and find that the specific heat divided by temperature $C/T$ shows sudden drop at $\sim T_c/5$ and goes to zero with further decreasing temperature. These results indicate the presence of two distinct superconducting gaps in Lu$_{2}$Fe$_{3}$Si$_{5}$, similar to a typical two-gap superconductor MgB$_{2}$. We also report Hall coefficients, band structure calculation, and the anisotropy of upper critical fields for Lu$_{2}$Fe$_{3}$Si$_{5}$, which support the anisotropic multiband nature and reinforce the existence of two superconducting gaps in Lu$_{2}$Fe$_{3}$Si$_{5}$.Comment: 5 pages, 5 figure

Instantons on ALE spaces and Super Liouville Conformal Field Theories

We provide evidence that the conformal blocks of N=1 super Liouville conformal field theory are described in terms of the SU(2) Nekrasov partition function on the ALE space O_{P^1}(-2).Comment: 10 page

Uhlenbeck-Donaldson compactification for framed sheaves on projective surfaces

We construct a compactification $M^{\mu ss}$ of the Uhlenbeck-Donaldson type for the moduli space of slope stable framed bundles. This is a kind of a moduli space of slope semistable framed sheaves. We show that there exists a projective morphism $\gamma \colon M^{ss} \to M^{\mu ss}$, where $M^{ss}$ is the moduli space of S-equivalence classes of Gieseker-semistable framed sheaves. The space $M^{\mu ss}$ has a natural set-theoretic stratification which allows one, via a Hitchin-Kobayashi correspondence, to compare it with the moduli spaces of framed ideal instantons.Comment: 18 pages. v2: a few very minor changes. v3: 27 pages. Several proofs have been considerably expanded, and more explanations have been added. v4: 28 pages. A few minor changes. Final version accepted for publication in Math.

Vortex reflection at boundaries of Josephson-junction arrays

We study the propagation properties of a single vortex in square Josephson-junction arrays (JJA) with free boundaries and subject to an applied dc current. We model the dynamics of the JJA by the resistively and capacitively shunted junction (RCSJ) equations. For zero Stewart-McCumber parameter $\beta_c$ we find that the vortex always escapes from the array when it gets to the boundary. For $\beta_c\geq 2.5$ and for low currents we find that the vortex escapes, while for larger currents the vortex is reflected as an antivortex at one edge and the antivortex as a vortex at the other, leading to a stationary oscillatory state and to a non-zero time-averaged voltage. The escape and the reflection of a vortex at the array edges are qualitatively explained in terms of a coarse-grained model of a vortex interacting logarithmically with its image. We also discuss the case when the free boundaries are at $45$ degrees with respect to the direction of the vortex motion. Finally, we discuss the effect of self-induced magnetic fields by taking into account the full-range inductance matrix of the array, and find qualitatively equivalent results.Comment: 14 pages RevTex, 9 Postscript figure

Matone's Relation in the Presence of Gravitational Couplings

The prepotential in N=2 SUSY Yang-Mills theories enjoys remarkable properties. One of the most interesting is its relation to the coordinate on the quantum moduli space $u=$ that results into recursion equations for the coefficients of the prepotential due to instantons. In this work we show, with an explicit multi-instanton computation, that this relation holds true at arbitrary winding numbers. Even more interestingly we show that its validity extends to the case in which gravitational corrections are taken into account if the correlators are suitably modified. These results apply also to the cases in which matter in the fundamental and in the adjoint is included. We also check that the expressions we find satisfy the chiral ring relations for the gauge case and compute the first gravitational correction.Comment: 21 page

A Measurement of Neutrino Charged Current Interactions and a Search for Muon Neutrino Disappearance with the Fermilab Booster Neutrino Beam

In this thesis, we report on a measurement of muon neutrino inclusive charged current interactions on carbon in the few GeV region, using the Fermilab Booster Neutrino Beam. The all neutrino mode data collected in the SciBooNE experiment is used for this analysis. We collected high-statistics CC interaction sample at SciBooNE, and extracted energy dependent inclusive charged current interaction rates and cross sections for a wide energy range from 0.25 GeV to {approx}3 GeV. We measure the interaction rates with 6-15% precision, and the cross sections with 10-30% precision. We also made an energy integrated measurements, with the precisions of 3% for the rate, and 8% for the cross section measurements. This is the first measurement of the CC inclusive cross section on carbon around 1 GeV. This inclusive interaction measurement is nearly free from effects of hadron re-interactions in the nucleus. Hence, it is complementary to other exclusive cross section measurements, and essential to understand the neutrino interaction cross sections in the few GeV region, which is relevant to ongoing and future neutrino oscillation experiments. This analysis also provides the normalization for SciBooNE's previous cross section ratio measurements for charged current coherent pion production and neutral current neutral pion production. Then, a precise comparison between our previous measurements and the model predictions becomes possible. The result of the interaction rate measurement is used to constrain the product of the neutrino flux and the cross section at the other experiment on the Fermilab Booster Neutrino Beam: Mini-BooNE. We conducted a search for short-baseline muon neutrino disappearance using data both from SciBooNE and MiniBooNE, to test a possible neutrino oscillation with sterile neutrinos which is suggested by the LSND experiment. With this constraint by SciBooNE, we significantly reduced the flux and the cross section uncertainties at MiniBooNE, and achieved the world best sensitivity for the {nu}{sub {mu}} disappearance at 0.5 < {Delta}m{sup 2} < 30 (eV{sup 2}). We found no significant oscillation signal, and set one of the world strongest limits for the sterile neutrino models

Search for muon neutrion disappearance in a short-baseline accelerator neutrino beam

Neutrino oscillations have been observed and confirmed at {Delta}m{sup 2} {approx} 10{sup -3} and 10{sup -5} eV{sup 2} with various experiments. While oscillations at other mass splittings are prohibited by the current standard model, the LSND experiment observed an excess of electron antineutrinos in a muon antineutrino beam, indicating a possible oscillation at {Delta}m{sup 2} {approx} 1 eV{sup 2}. To test the oscillation at {Delta}m{sup 2} {approx} 1 eV{sup 2}, we search for muon neutrino disappearance using the Fermilab Booster Neutrino beamline and two experiments, SciBooNE and MiniBooNE. The neutrino fluxes are measured in the SciBooNE and MiniBooNE detectors, located at 100 m and 540 m downstream from the neutrino production target, respectively. We collected beam data from June 2007 through August 2008 with SciBooNE, and over a five year period with MiniBooNE. A preliminary sensitivity for a joint v{sub {mu}} disappearance search is presented

Status of FNAL SciBooNE experiment

SciBooNE is a new experiment at FNAL which will make precision neutrino-nucleus cross section measurements in the one GeV region. These measurements are essential for the future neutrino oscillation experiments. We started data taking in the antineutrino mode on June 8, 2007, and collected 5.19 x 10{sup 19} protons on target (POT) before the accelerator shutdown in August. The first data from SciBooNE are reported in this article