Light mixed sneutrinos as thermal dark matter

In supersymmetric models with Dirac neutrino masses, a left-right mixed sneutrino can be a viable dark matter candidate. We examine the MSSM+$\tilde\nu_R$ parameter space where this is the case with particular emphasis on light sneutrinos with masses below 10 GeV. We discuss implications for direct and indirect dark matter searches, including the relevant uncertainties, as well as consequences for collider phenomenology.Comment: 33 pages, 14 figures; one figure and references adde

Detection of an exoplanet around the evolved K giant HD 66141

Aims. We have been carrying out a precise radial velocity (RV) survey for K giants to search for and study the origin of the lowamplitude and long-periodic RV variations. Methods. We present high-resolution RV measurements of the K2 giant HD 66141 from December 2003 to January 2011 using the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory (BOAO). Results. We find that the RV measurements for HD 66141 exhibit a periodic variation of 480.5 +/- 0.5 days with a semi-amplitude of 146.2 +/- 2.7 m/s. The Hipparcos photometry and bisector velocity span (BVS) do not show any obvious correlations with RV variations. We find indeed 706.4 +/- 35.0 day variations in equivalent width (EW) measurements of H_alpha line and 703.0 +/- 39.4 day variations in a space-born measurements 1.25{\mu} flux of HD 66141 measured during COBE/DIRBE experiment. We reveal that a mean value of long-period variations is about 705 +/- 53 days and the origin is a rotation period of the star and variability that is caused by surface inhomogeneities. For the 480 day periods of RV variations an orbital motion is the most likely explanation. Assuming a stellar mass of 1.1 +/- 0.1 M_Sun? for HD 66141, we obtain a minimum mass for the planetary companion of 6.0 +/- 0.3 M_Jup with an orbital semi-major axis of 1.2 +/- 0.1 AU and an eccentricity of 0.07 +/- 0.03.Comment: 7 pages, 10 figures, 3 tables, accepted for publisation in Astronomy & Astrophysic

Low-amplitude and long-period radial velocity variations in giants HD 3574, 63 Cygni, and HD 216946 (Research Note)

Aims. We study the low-amplitude and long-period variations in evolved stars using precise radial velocity measurements. Methods. The high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) was used from September 2004 to May 2014 as part of the exoplanet search program at the Bohyunsan Optical Astronomy Observatory (BOAO). Results. We report the detection of low-amplitude and long-period orbital radial velocity variations in three evolved stars, HD 3574, 63 Cyg, and HD 216946. They have periods of 1061, 982, and 1382 days and semi-amplitudes of 376, 742, and 699 m/s, respectively.Comment: 6 pages, 7 figures, 4 tables, accepted for publisation in Astronomy & Astrophysic

Study of Low Energy Spin Rotons in the Fractional Quantum Hall Effect

Motivated by the discovery of extremely low energy collective modes in the fractional quantum Hall effect (Kang, Pinczuk {\em et al.}), with energies below the Zeeman energy, we study theoretically the spin reversed excitations for fractional quantum Hall states at $\nu=2/5$ and 3/7 and find qualitatively different behavior than for $\nu=1/3$. We find that a low-energy, charge-neutral "spin roton," associated with spin reversed excitations that involve a change in the composite-fermion Landau level index, has energy in reasonable agreement with experiment.Comment: Postscript figures included. Accepted in Phys. Rev. B (Rapid Communication

Anisotropy of in-plane magnetization due to nodal gap structure in the vortex state

We examine the interplay between anisotropy of the in-plane magnetization and the nodal gap structure on the basis of the approximate analytic solution in the quasiclassical formalism. We show that a four-fold oscillation appears in the magnetization, and its amplitude changes sign at an intermediate field. The high-field oscillation originates from the anisotropy of the upper critical field, while the low-field behavior can be understood by the thermally activated quasiparticles near nodes depending on the applied field angles. The temperature dependence of the magnetization also shows a similar sign change. The anisotropy of the magnetization offers a possible measurement to identify the gap structure directly for a wide class of type II superconductors.Comment: 4 pages, 4 figure

A Note on Tachyons in the D3+D3ˉD3+{\bar {D3}} System

The periodic bounce of Born-Infeld theory of $D3$-branes is derived, and the BPS limit of infinite period is discussed as an example of tachyon condensation. The explicit bounce solution to the Born--Infeld action is interpreted as an unstable fundamental string stretched between the brane and its antibrane.Comment: 10 pages, 2 figures. v2: minor changes, acknowledgement added; v3: explanations and references added. Final version to appear in Mod. Phys. Lett.

Chirality in Quantum Computation with Spin Cluster Qubits

We study corrections to the Heisenberg interaction between several lateral, single-electron quantum dots. We show, using exact diagonalization, that three-body chiral terms couple triangular configurations to external sources of flux rather strongly. The chiral corrections impact single qubit encodings utilizing loops of three or more Heisenberg coupled quantum dots.Comment: 5 pages, 2 figure

Convergence of finite difference method for the generalized solutions of Sobolev equations

In this paper, finite difference method is applied to approximate the generalized solutions of Sobolev equations. Using the Steklov mollifier and BrambleHilbert Lemma, a priori error estimates in discrete L2 as well as in discrete H1 norms are derived first for the semidiscrete methods. For the fully discrete schemes, both backward Euler and CrankNicolson methods are discussed and related error analyses are also presented

Tunable far infrared studies of molecular parameters in support of stratospheric measurements

Lab studies were made in support of far infrared spectroscopy of the stratosphere using the Tunable Far InfraRed (TuFIR) method of ultrahigh resolution spectroscopy and, more recently, spectroscopic and retrieval calculations performed in support of satellite-based atmospheric measurement programs: the Global Ozone Monitoring Experiment (GOME), and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY)