A Radial Velocity Survey for LMC Microlensed Sources

We propose a radial velocity survey with the aim to resolve the current dispute on the LMC lensing: in the pro-macho hypothesis the lenses are halo white dwarfs or machos in general; in the pro-star hypothesis both the lenses and the sources are stars in various observed or hypothesized structures of the Magellanic Clouds and the Galaxy. Star-star lensing should prefer sources at the backside or behind the LMC disc because lensing is most efficient if the source is located a few kpc behind a dense screen of stars, here the thin disc of the LMC. This signature of self-lensing can be looked for by a radial velocity survey since kinematics of the stars at the back can be markedly different from that of the majority of stars in the cold, rapidly rotating disc of the LMC. Detailed simulations of effect together with optimal strategies of carrying out the proposed survey are reported here. Assuming that the existing 30 or so alerted stars in the LMC are truely microlensed stars, their kinematics can test the two lensing scenarios; the confidence level varies with the still very uncertain structure of the LMC. Spectroscopy of the existing sample and future events requires about two or three good-seeing nights per year at a 4m-8m class southern telescope, either during the amplification phase or long after.Comment: minor changes of text, ApJ accepte

Calculable inverse-seesaw neutrino masses in supersymmetry

We provide a scenario where naturally small and calculable neutrino masses arise from a supersymmetry breaking renormalization-group-induced vacuum expectation value. We adopt a minimal supergravity scenario without ad hoc supersymmetric mass parameters. The lightest supersymmetric particle can be an isosinglet scalar neutrino state, potentially viable as WIMP dark matter through its Higgs new boson coupling. The scenario leads to a plethora of new phenomenological implications at accelerators including the Large Hadron Collider.Comment: LaTeX, 5 pages, 4 figures. Comments and references added. Final version to appear in PR

Probing neutrino transition magnetic moments with coherent elastic neutrino-nucleus scattering

We explore the potential of current and next generation of coherent elastic neutrino-nucleus scattering (CE$\nu$NS) experiments in probing neutrino electromagnetic interactions. On the basis of a thorough statistical analysis, we determine the sensitivities on each component of the Majorana neutrino transition magnetic moment (TMM), $\left \vert \Lambda_i \right \vert$, that follow from low-energy neutrino-nucleus experiments. We derive the sensitivity to neutrino TMM from the first CE$\nu$NS measurement by the COHERENT experiment, at the Spallation Neutron Source. We also present results for the next phases of COHERENT using HPGe, LAr and NaI[Tl] detectors and for reactor neutrino experiments such as CONUS, CONNIE, MINER, TEXONO and RED100. The role of the CP violating phases in each case is also briefly discussed. We conclude that future CE$\nu$NS experiments with low-threshold capabilities can improve current TMM limits obtained from Borexino data.Comment: 25 pages, 8 figures, 2 tables, analysis updated; conclusions unchanged; references added; 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)

Implications of the first detection of coherent elastic neutrino-nucleus scattering (CEvNS) with Liquid Argon

The CENNS-10 experiment of the COHERENT collaboration has recently reported the first detection of coherent-elastic neutrino-nucleus scattering (CEvNS) in liquid Argon with more than $3 \sigma$ significance. In this work, we exploit the new data in order to probe various interesting parameters which are of key importance to CEvNS within and beyond the Standard Model. A dedicated statistical analysis of these data shows that the current constraints are significantly improved in most cases. We derive a first measurement of the neutron rms charge radius of Argon, and also an improved determination of the weak mixing angle in the low energy regime. We also update the constraints on neutrino non-standard interactions, electromagnetic properties and light mediators with respect to those derived from the first COHERENT-CsI data.Comment: discussion expanded including light mediators and nuclear uncertainties, figures added, references added. V3: Fig. 7 corrected, conclusions unchange

On the description of non-unitary neutrino mixing

Neutrino oscillations are well established and the relevant parameters determined with good precision, except for the CP phase, in terms of a unitary lepton mixing matrix. Seesaw extensions of the Standard Model predict unitarity deviations due to the admixture of heavy isosinglet neutrinos. We provide a complete description of the unitarity and universality deviations in the light neutrino sector. Neutrino oscillation experiments involving electron or muon neutrinos and anti-neutrinos are fully described in terms of just three new real parameters and a new CP phase, in addition to the ones describing oscillations with unitary mixing. Using this formalism we describe the implications of non-unitarity for neutrino oscillations and summarize the model-independent constraints on heavy neutrino couplings that arise from current experiments.Comment: 28 pages, 8 figures, typos corrected, modified bounds on non-unitarity parameters, new figs 3 and

Novel approaches for portfolio construction using second order stochastic dominance

In the last decade, a few models of portfolio construction have been proposed which apply Second Order Stochastic Dominance (SSD) as a choice criterion. SSD approach requires the use of a reference distribution which acts as a benchmark. The return distribution of the computed portfolio dominates the benchmark by the SSD criterion. The benchmark distribution naturally plays an important role since di erent benchmarks lead to very di erent portfolio solutions. In this paper we describe a novel concept of reshaping the benchmark distribution with a view to obtaining portfolio solutions which have enhanced return distributions. The return distribution of the constructed portfolio is considered enhanced if the left tail is improved, the downside risk is reduced and the standard deviation remains within a speci ed range. We extend this approach from long only to long-short strategies which are used by many hedge fund and quant fund practitioners. We present computational results which illustrate (i) how this approach leads to superior portfolio performance (ii) how signi cantly better performance is achieved for portfolios that include shorting of assets

A new neutrino mass sum rule from inverse seesaw

A class of discrete flavor-symmetry-based models predicts constrained neutrino mass matrix schemes that lead to specific neutrino mass sum-rules (MSR). One of these implies in a lower bound on the effective neutrinoless double beta mass parameter, even for normal hierarchy neutrinos. Here we propose a new model based on the S4 flavor symmetry that leads to the new neutrino mass sum-rule and discuss how to generate a nonzero value for the reactor mixing angle indicated by recent experiments, and the resulting correlation with the solar mixing angle.Comment: 14 pages, 4 figure

Classical realization of two-site Fermi-Hubbard systems

A classical wave optics realization of the two-site Hubbard model, describing the dynamics of interacting fermions in a double-well potential, is proposed based on light transport in evanescently-coupled optical waveguides.Comment: 4 page

X-ray monitoring of classical novae in the central region of M31. III. Autumn and winter 2009/10, 2010/11 and 2011/12

[Abridged] Classical novae (CNe) represent the major class of supersoft X-ray sources (SSSs) in the central region of our neighbouring galaxy M31. We performed a dedicated monitoring of the M31 central region, aimed to detect SSS counterparts of CNe, with XMM-Newton and Chandra between Nov and Mar of the years 2009/10, 2010/11 and 2011/12. In total we detected 24 novae in X-rays. Seven of these sources were known from previous observations, including the M31 nova with the longest SSS phase, M31N~1996-08b, which was found to fade below our X-ray detection limit 13.8 yr after outburst. Of the new discoveries several novae exhibit significant variability in their short-term X-ray light curves with one object showing a suspected period of about 1.3 h. We studied the SSS state of the most recent outburst of a recurrent nova which had previously shown the shortest time ever observed between two outbursts (about 5 yr). The total number of M31 novae with X-ray counterpart was increased to 79 and we subjected this extended catalogue to detailed statistical studies. Four previously indicated correlations between optical and X-ray parameters could be confirmed and improved. We found indications that the multi-dimensional parameter space of nova properties might be dominated by a single physical parameter. We discuss evidence for a different X-ray behaviour of novae in the M31 bulge and disk. Exploration of the multi-wavelength parameter space of optical and X-ray measurements is shown to be a powerful tool for examining properties of extragalactic nova populations. While there are hints that the different stellar populations of M31 (bulge vs disk) produce dissimilar nova outbursts, there is also growing evidence that the overall behaviour of an average nova might be understood in surprisingly simple terms.Comment: 39 pages (half of them for 9 tables), 14 figures, accepted for publication in A&A; updated after language editing stag