Non-Hermitian shortcut to stimulated Raman adiabatic passage

We propose a non-Hermitian generalization of stimulated Raman adiabatic passage (STIRAP), which allows one to increase speed and fidelity of the adiabatic passage. This is done by adding balanced imaginary (gain/loss) terms in the diagonal (bare energy) terms of the Hamiltonian and choosing them such that they cancel exactly the nonadiabatic couplings, providing in this way an effective shortcut to adiabaticity. Remarkably, for a STIRAP using delayed Gaussian-shaped pulses in the counter-intuitive scheme the imaginary terms of the Hamiltonian turn out to be time independent. A possible physical realization of non-Hermitian STIRAP, based on light transfer in three evanescently-coupled optical waveguides, is proposed.Comment: 7 pages, 4 figure

How sensitive is a neutrino factory to the angle θ13\theta_{13}?

We consider the impact of non-standard interactions of neutrinos (NSI) on the determination of neutrino mixing parameters at a neutrino factory using \pnu{e}\to\pnu{\mu} ``golden channels'' for the measurement of $\theta_{13}$. We show how a small residual NSI leads to a drastic loss in sensitivity in $\theta_{13}$, of up to two orders of magnitude. This can be somewhat overcome if two baselines are combined.Comment: 4 pages, 3 figure

Quantum simulation of the Riemann-Hurwitz zeta function

We propose a simple realization of a quantum simulator of the Riemann-Hurwitz (RH) \zeta\ function based on a truncation of its Dirichlet representation. We synthesize a nearest-neighbour-interaction Hamiltonian, satisfying the property that the temporal evolution of the autocorrelation function of an initial bare state of the Hamiltonian reproduces the RH function along the line \sigma+i \omega t of the complex plane, with \sigma>1. The tight-binding Hamiltonian with engineered hopping rates and site energies can be implemented in a variety of physical systems, including trapped ion systems and optical waveguide arrays. The proposed method is scalable, which means that the simulation can be in principle arbitrarily accurate. Practical limitations of the suggested scheme, arising from a finite number of lattice sites N and from decoherence, are briefly discussed.Comment: 6 pages, 3 figure

Chern-Simons anomaly as polarization effect

The parity violating Chern-Simons term in the epoch before the electroweak phase transition can be interpreted as a polarization effect associated to massless right-handed electrons (positrons) in the presence of a large-scale seed hypermagnetic field. We reconfirm the viability of a unified seed field scenario relating the cosmological baryon asymmetry and the origin of the protogalactic large-scale magnetic fields observed in astronomy.Comment: 4 pages, latex, matches published versio

Inverse tri-bimaximal type-III seesaw and lepton flavor violation

We present a type-III version of inverse seesaw or, equivalently an inverse version of type-III seesaw. Naturally small neutrino masses arise at low-scale from the exchange of neutral fermions transforming as hyperchargeless SU(2) triplets. In order to implement tri-bimaximal lepton mixing we supplement the minimal SU(3)xSU(2)xU(1) gauge symmetry with an A4-based flavor symmetry. Our scenario induces lepton flavour violating (LFV) three body decays that can proceed at the tree level, while radiative li to lj gamma decays and mu-e conversion in nuclei are also expected to be sizeable. LFV decays are related by the underlying flavor symmetry and the new fermions are also expected to be accessible for study at the Large Hadron Collider (LHC)

Radiative zone solar magnetic fields and g-modes

We consider a generalized model of seismic-wave propagation that takes into account the effect of a central magnetic field in the Sun. We determine the g-mode spectrum in the perturbative magnetic field limit using a one-dimensional Magneto-Hydrodynamics (MHD) picture. We show that central magnetic fields of about 600-800 kG can displace the pure g-mode frequencies by about 1%, as hinted by the helioseismic interpretation of GOLF observations.Comment: 6 pages, 4 figures; final version to appear in MNRA

Novel Supersymmetric SO(10) Seesaw Mechanism

We propose a new seesaw mechanism for neutrino masses within a class of supersymmetric SO(10) models with broken D-parity. It is shown that in such scenarios the B-L scale can be as low as TeV without generating inconsistencies with gauge coupling unification nor with the required magnitude of the light neutrino masses. This leads to a possibly light new neutral gauge boson as well as relatively light quasi-Dirac heavy leptons. These particles could be at the TeV scale and mediate lepton flavour and CP violating processes at appreciable levels.Comment: 4 pages, 3 figures, revtex4, references added, typos corrected, sharper discussion of the RGEs give

Status of three-neutrino oscillations after the SNO-salt data

We perform a global analysis of neutrino oscillation data in the framework of three neutrinos, including the recent improved measurement of the neutral current events at SNO. In addition to all current solar neutrino data we take into account the reactor neutrino data from KamLAND and CHOOZ, the atmospheric neutrino data from Super-Kamiokande and MACRO, as well as the first spectral data from the K2K long baseline accelerator experiment. The up-to-date best fit values and allowed ranges of the three-flavour oscillation parameters are determined from these data. Furthermore, we discuss in detail the status of the small parameters alpha = Delta_m^2_Sol / Delta_m^2_Atm and sin^2(theta_13), which fix the possible strength of CP violating effects in neutrino oscillations.Comment: 16 pages, LaTeX file using RevTEX4, 10 figures and 1 table included. The conclusions reached in version 1 regarding the restriction on sin^2(theta_13) are now corrected, the solar bound is weaker than that from reactors even after the inclusion of the SNO salt data. In addition the full data set has now been reanalized using the pull method instead of the standard chi-square approach. A few references have also been adde