Search

Detection of a stochastic background of gravitational waves is likely to occur in the next few years. Beyond searches for the isotropic component of SGWBs, there have been various mapping methods proposed to target anisotropic backgrounds. Some of these methods have been applied to data taken by the Laser Interferometer Gravitational-wave Observatories (LIGO) and Virgo. Specifically, these directional searches have focused on mapping the intensity of the signal on the sky via maximum likelihood solutions. We compare this intensity mapping approach to a previously proposed, but never employed, amplitude-phase mapping method to understand whether this latter approach may be employed in future searches. We build up our understanding of the differences between these two approaches by analysing simple toy models of time-stream data, and run mock-data mapping tests for the two methods. We find that the amplitude-phase method is only applicable to the case of a background which is phase-coherent on large scales or, at the very least, has an intrinsic coherence scale that is larger than that of the detector. Otherwise, the amplitude-phase mapping method leads to a loss of overall information, with respect to both phase and amplitude. Since we do not expect these phase-coherent properties to hold for any of the gravitational-wave background signals we hope to detect in the near future, we conclude that intensity mapping is the preferred method for such backgrounds., 15 pages, 4 figures

We introduce a unified formalism to describe both timing and astrometric perturbations induced on astrophysical point sources by gravitational waves using a complex spin field on the sphere. This allows the use of spin-weighted spherical harmonics to analyse "astrochronometric" observables. This approach simplifies the interpretation and simulation of anisotropies induced in the observables by gravitational waves. It also allows a simplified derivation of angular cross-spectra of the observables and their relationship with generalised Hellings-Downs correlation functions. The spin-weighted formalism also allows an explicit connection between correlation components and the spin of gravitational wave polarisations and any presence of chirality. We also calculate expected signal-to-noise ratios for observables to compare the utility of timing and deflection observables., Comment: 15 pages, 7 figures, 4 tables

Background and aims People who use drugs (PWUD) represent an active reservoir of HCV infection. The prevalence of chronic HCV infection in PWUD in Italy remains unknown because of the lack of systematic screening. Thanks to direct-acting antiviral agents (DAAs), hepatitis C can now be cured in most patients. Thus, the next challenge is to provide linkage-to-care for these patients. Methods In this scenario, we conducted a screening programme in PWUD attending seven Addiction Centers in Southern Italy, as well as a treatment programme in the Liver Unit of the University Hospital of Salerno. We used the OraQuick HCV antibody test to screen the PWUD (from 1 April to 30 September 2018). Results 593 subjects were consecutively enrolled in the programme; 250 (41.8%) were HCV-Ab-positive. 143 (24.1%) were aware of their infection and had been HCV-RNA-tested: 83 were positive and 60 negative. The remaining 107 subjects (18.1%) had never previously been tested and were unaware of their infection. A total of 160 (26.9%) HCV RNA-positive patients were found and offered antiviral therapy with DAAs. The sustained virological response rate was 98.5% and no adverse events were recorded. Two patients voluntarily discontinued treatment. No reinfections have been recorded to date. Conclusions The prevalence of HCV-Ab positivity was high in the PWUDs enrolled in this study, and almost half the patients were unaware of being HCV-positive. The linkage-to-care provided was safe and effective, and no case of reinfection was recorded.

How did the universe evolve? The fine angular scale (l>1000) temperature and polarization anisotropies in the CMB are a Rosetta stone for understanding the evolution of the universe. Through detailed measurements one may address everything from the physics of the birth of the universe to the history of star formation and the process by which galaxies formed. One may in addition track the evolution of the dark energy and discover the net neutrino mass. We are at the dawn of a new era in which hundreds of square degrees of sky can be mapped with arcminute resolution and sensitivities measured in microKelvin. Acquiring these data requires the use of special purpose telescopes such as the Atacama Cosmology Telescope (ACT), located in Chile, and the South Pole Telescope (SPT). These new telescopes are outfitted with a new generation of custom mm-wave kilo-pixel arrays. Additional instruments are in the planning stages., Science White Paper submitted to the US Astro2010 Decadal Survey. Full list of 177 author available at http://cmbpol.uchicago.edu

I put metastable supersymmetry breaking in a cosmological context. I argue that under reasonable assumptions, the cooling down early Universe favors metastable SUSY-breaking vacua over the stable supersymmetric vacua. To illustrate the general argument, I analyze the early-Universe history of the Intriligator-Seiberg-Shih model., Plenary talk at PASCOS 07 converence, based on hep-th/0611018. 8 dense pages, LaTeX+AIP6x9+PStricks

A string field theory(SFT) nonlocal model of the cosmological dark energy providing w, Comment: Talk at PASCOS 2007, to appear in the proceedings, 5 pages, latex

The evidence for an accelerating Hubble expansion appears to have confirmed the heuristic prediction, from causal set theory, of a fluctuating and ``ever-present'' cosmological term in the Einstein equations. A more concrete phenomenological model incorporating this prediction has been devised and tested, but it remains incomplete. I will review these developments and also mention a possible consequence for the dimensionality of spacetime., plainTeX, 13 pages. To appear in the proceedings of the PASCOS-07 Conference, held July, 2007, London, England. Most current version is available at http://www.physics.syr.edu/~sorkin/some.papers/ (or wherever my home-page may be)

We have recently shown that, if the inflaton has a nonzero vacuum expectation value, it generically couples to any matter fields that appear in the superpotential at the tree level, and to any gauge sectors through anomalies in the supergravity. Through these processes, the inflaton decays into the supersymmetry breaking sector, producing many gravitinos. The inflaton also directly decays into a pair of the gravitinos. Taking account of these processes, we derive constraints on both inflation models and supersymmetry breaking scenarios for avoiding overproduction of the gravitinos., Talk given at PASCOS-07, to appear in the proceedings. 4 pages

By resorting to previous results on flavor mixing in Quantum Field Theory, we show how to consistently define flavor states of mixed neutrinos as eigenstates of the flavor charge operators., 4 pages, presented at 13th International Symposium on Particles, Strings and Cosmology, PASCOS-07, 2-7 July 2007, Imperial College London

In a compact space with non-trivial cycles, for sufficiently small values of the compact dimensions, charge conjugation (C), spatial reflection (P) and time reversal (T) are spontaneously broken in QCD. The order parameter for the symmetry breaking is the trace of the Wilson line wrapping around the compact dimension, which acquires an imaginary part in the broken phase. We show that a physical signature for the symmetry breaking is a persistent baryonic current wrapping in the compact directions. The existence of such a current is derived analytically at first order in perturbation theory and confirmed in the non-perturbative regime by lattice simulations., 4 pages, 2 figures, based on the poster presented by B. Lucini at Pascos 07

A phaenomenological DM-DE coupling could indicate their common origin. Various constraint however exist to such coupling; here we outline that it can suppress Meszaros' effect, yielding transfered spectra with a softer bending above k_{hor,eq}. It could be therefore hard to reconcile these models with both CMB and deep sample data, using a constant spectral index., 4 pages, 4 figures, proceedings of PASCOS 2007, 2-7 July, London

We study the viability of the lightest neutralino as a dark matter candidate in the Next-to-Minimal Supersymmetric Standard Model. Taking into account accelerator constraints as well as bounds on low-energy observables, and imposing consistency with present bounds on the neutralino relic density, we address the prospects for the direct detection of neutralino dark matter. We find regions of the allowed parameter space where the neutralino detection cross section is within the reach of dark matter detectors, essentially owing to the presence of very light singlet-like Higgses, and to either singlino dominated or very light neutralinos., Comment: 4 pages, 2 figures. Presented at 13th International Symposium on Particles, Strings and Cosmology (PASCOS 07), London, England, 2-7 Jul 2007

In a braneworld description of our universe, we must allow for the possibility of having dynamical branes around the time of the big bang. Some properties of such domain walls in motion are discussed here, for example the ability of negative-tension domain walls to bounce off spacetime singularities and the consequences for cosmological perturbations. In this context, we will also review a colliding branes solution of heterotic M-theory that has been proposed as a model for early universe cosmology., 4 pages. Contribution to the proceedings of PASCOS-07, 2-7 July 2007, Imperial College, London

Quadratic curvature Gauss-Bonnet gravity may be the solution to the dark energy problem, but a large coupling strength is required. This can lead to conflict with laboratory and planetary tests of Newton's law, as well as light bending. The corresponding constraints are derived. If applied directly to cosmological scales, the resulting bound on the density fraction is |Omega_GB| < 3.6 x 10^-32., 4 pages, PASCOS-07 conference proceedings

Recently, path equations have been obtained for charged, spinning objects in brane world models, using a modified Bazanski Lagrangian. In this study, path deviation equations of extended objects are derived. The significance of moving extended objects in brane world models is examined. Motion in non- symmetric brane world models is also considered., A paper presented at the Thirteenth International Symposium on Particles, Strings and Cosmology PASCOS-07, held in London, 2-7 July 2007

Quantum mechanics is 'emergent' if a statistical treatment of large scale phenomena in a locally deterministic theory requires the use of quantum operators. These quantum operators may allow for symmetry transformations that are not present in the underlying deterministic system. Such theories allow for a natural explanation of the existence of gauge equivalence classes (gauge orbits), including the equivalence classes generated by general coordinate transformations. Thus, local gauge symmetries and general coordinate invariance could be emergent symmetries, and this might lead to new alleys towards understanding the flatness problem of the Universe., 10 pages, 1 figure. Presented at PASCOS 13, Imperial College, London, July 6, 2007

We present a 6D orbifold model on $T^2/\Z2$ which emerges as intermediate step in the compactification of the heterotic string to the supersymmetric standard model in four dimensions. It has $\SU6$ gauge symmetry in the bulk and two pairs of inequivalent fixed points with unbroken $\SU5$ and $\SU2 \times \SU4$ symmetry, respectively. All anomalies are cancelled by the Green-Schwarz mechanism. Two quark-lepton generations are located at the $\SU5$ branes, the third family is composed of split bulk hypermultiplets. The model has vacua with partial or full gauge-Higgs unification and non-vanishing Yukawa couplings which generically avoid the unsuccessful $\SU5$ mass relations., Comment: Talk given at 13th International Symposium on Particles, Strings and Cosmology (PASCOS 07), London, England, 2-7 Jul 2007

The implications of brane motion in angular directions of Calabi-Yau flux compactifications are discussed from the point of view of an observer living on the worldvolume of the brane and from the point of view of an observer living elsewhere in the three non-compact dimensions. The brane observer can experience cosmological bounces and cyclic behavior of the scale factor induced by centrifugal angular momentum barriers. Observers living elsewhere in the compactification experience marginally prolonged periods of inflation due to large angular momentum (spinflation). The presence of spinflaton fields (or other fields with non-standard kinetic terms) during inflation may lead to interesting observational signatures in the cosmic microwave background radiation., Comment: 8 pages, 3 figures; To appear in proceedings of PASCOS-07, 2-7 July 2007, Imperial College, London

We point out that thermal relic abundance of dark matter is strongly altered by a non‐perturbative effect called the Sommerfeld enhancement, when constituent particles of the dark matter are SU(2)L non‐singlet and much heavier than the weak gauge bosons. Typical candidates are the heavy wino and higgsino. We investigate the non‐perturbative effect on the relic abundance of dark matter for the wino as an example. We show that its thermal abundance is reduced by 50% compared to the perturbative result. The wino mass consistent with the observed dark matter abundance turns out to be 2.7 TeV

I discuss the possibility of using a massive vector field to generate the density perturbation in the Universe. I find that a scale-invariant superhorizon spectrum of vector field perturbations is possible to generate during inflation. The associated curvature perturbation is imprinted onto the Universe following the curvaton scenario. The mechanism does not generate a long-range anisotropy because an oscillating massive vector field behaves as a pressureless isotropic fluid., Comment: In proceedings of 13th International Symposium on Particles Strings and Cosmology, PASCOS-07, 4pp

We analyze the effect of variation of fundamental couplings and mass scales on primordial nucleosynthesis in a systematic way. The first step establishes the response of primordial element abundances to the variation of a large number of nuclear physics parameters, including nuclear binding energies. We find a strong influence of the n‐p mass difference, of the nucleon mass and of A = 3,4,7 binding energies. A second step relates the nuclear parameters to the parameters of the Standard Model of particle physics. The deuterium, and, above all, 7Li abundances depend strongly on the average light quark mass. We calculate the behaviour of abundances when variations of fundamental parameters obey relations arising from grand unification. We also discuss the possibility of a substantial shift in the lithium abundance while the deuterium and 4He abundances are only weakly affected.

Nonlocal cosmological models derived from String Field Theory are considered. A new method for constructing rolling tachyon solutions in the FRW metric in two field configuration is proposed and solutions of the Friedman equations with nonlocal operator are presented. The cosmological properties of these solutions are discussed., 4 pages, 2 figures. Contribution to the proceedings of PASCOS-07, 2-7 July 2007, Imperial College, London

We present a new model of dark energy which could explain the observed accelerated expansion of our Universe. We show that a five‐dimensional Einstein‐Yang‐Mills theory defined in a flat Friedmann‐Robertson‐Walker universe compactified on a circle possesses degenerate vacua in four dimensions. The present Universe could be trapped in one of these degenerate vacua. With the natural requirement that the size of the extra dimension could be of the GUT scale or smaller, the energy density difference between the degenerate vacua and the true ground state can provide us with just the right amount of dark energy to account for the observed expansion rate of our Universe.

The pattern of neutrino masses and mixings is characteristically different from those observed in the quark sector. I discuss why this should be the case and what implications this has for the origin of quark and lepton masses, mixings and CP violation.

We discuss how the detailed geometry of warped compactification can significantly impact collider data. We show how the details of the cross section for dilepton production (such as the spacing, the width, and the peaks of the KK graviton resonances) for a generic class of warped throats which are closely related to the Randall‐Sundrum model depend sensitively on the precise shape of the warp factor.

Recent data and new data analysis methods show that most probably the parameter $w$ in the equation of state of the dark energy is smaller than -1 at low redshifts. We briefly review some of the models with such a property and without violating null energy condition. We investigate the difference between the observables and predictions of these models, and how they can be explored to single out or constrain the origin of dark energy and its properties., Comment: 4 papes, 2 figures. To appear in the proceedings of PASCOS-07 conference, Imperial College, London, UK, 2-7 July 2007

A class of generalized Randall-Sundrum type II (RS) brane-world models with Weyl fluid are confronted with the Gold supernovae data set and BBN constraints. We consider three models with different evolutionary history of the Weyl fluid, characterized by the parameter $\alpha$. For $\alpha=0$ the Weyl curvature of the bulk appears as dark radiation on the brane, while for $\alpha =2$ and 3 the brane radiates, leaving a Weyl fluid on the brane with energy density decreasing slower than that of (dark) matter. In each case the contribution $\Omega_d$ of the Weyl fluid represents but a few percent of the energy content of the Universe. All models fit reasonably well the Gold2006 data. The best fit model for $\alpha =0$ is for $\Omega_d=0.04$. In order to obey BBN constraints in this model however, the brane had to radiate at earlier times., Comment: 4 pages, 3 figures, to appear in the PASCOS-07 (13th International Symposium on Particles, Strings and Cosmology) Proceedings volume

We discuss the conjecture that for any supersymmetric solution of D = 10 or D = 11 supergravity consisting of a warped product of a d+1‐dimensional of anti‐de‐Sitter space with a Riemannian manifold M, there is a consistent Kaluza‐Klein truncation on M to a gauged supergravity theory in d+1‐dimensions for which the fields are dual to those in the superconformal current multiplet of the d‐dimensional dual SCFT. This means that any solution of the gauged supergravity theory can be uplifted on M to obtain an exact solution of D = 10 or D = 11 supergravity. We verify this conjecture for the most general class of supersymmetric AdS5 solutions of D = 11 supergravity by constructing an explicit KK reduction ansatz to minimal gauged supergravity in D = 5, at the level of the bosonic fields.

I discuss forms of high energy density matter in QCD. These include the Color Glass Condensate, the Glasma and the Quark Gluon Plasma. They all might be studied in ultra-relativistic heavy ion collisions, nd the Color Glass Condensate might also be probed in electron-hadron collisions. I present the properties of such matter and some aspects of what is known of their properties., Comment: Plenary talk presented at PASCOS 2007

The main goal of the NA48 experiments at the CERN SPS has been the search for direct CP violation (CPV) in kaon decays. In this article two selected results will be presented. In the neutral kaon sector, NA48 determined η+−, related to the parameters of indirect and direct CPV (η+− = e+e′), from data collected during a dedicated run in 1999 with a pure KL beam. Using a sample of 47000 KL→π+π− and 5 million KL→π±e∓ν, we extract |η+−| = (2.223±0.012)×10−3. In the charged kaon decays, NA48/2 has measured the asymmetry Ag = (g+−g−)/(g++g−). of the linear slope parameter g in the Dalitz plot of K±→3π decays from data collected in 2003 and 2004. Any non‐zero value of Ag would be evidence for direct CPV. A new technique of asymmetry measurement, involving simultaneous K+ and K− beam and a large data sample allowed a result of unprecedented precision. The charge asymmetry parameter was measured to be Agc = (−1.5±2.1)×10−4 with 3.11×109 K±→π±π+π− decays, and Agn = (1.8±1.8)×10−4 with 9.13×107 K±→π±π0π0 decays. The...

A most simple paraextension of the Wess‐Zumino model is investigated. As a parabosons‐parafermions system, this model forms a field theoretical realization of a supersymmetric Poincare algebra (SPA), where, the parasupercharges satisfy the bilinear commutations relations dictated by these types of systems. The closure of the transformations algebra is established with a bilinear product rule for the fermionic elements. Finally, we verify that these parasupercharges are really the generators of the (para)supersymmetric transformations.

Many of the open questions beyond the Standard Model will be addressed by the LHC, including the origin of mass, supersymmetry, dark matter and the possibility of large extra dimensions. A linear e+ e- collider (LC) with sufficient centre-of-mass energy would add considerable value to the capabilities of the LHC., Comment: 12 pages, 8 figures, Contribution to the Proceedings of the 13th International Symposium on Particles, Strings and Cosmology, PASCOS-07

There are solutions of Israel junction conditions that describe the detachment of a region of spacetime, a bubble, from what can be called the parent spacetime. In the past these solutions have been mostly considered in the context of inflationary cosmology (the so called baby universes). We will i) briefly review these ideas, ii) show that they can be of interest under more general settings and iii) present solutions where it is possible to create a universe at arbitrarily small energy cost. This could have interesting applications for quantum gravity and particle physics, besides cosmology.

In braneworld models coming from string theory one generally encounters massless scalar degrees of freedom -moduli- parameterizing the volume of small compact extra-dimensions. Here we discuss the effects of such moduli on Newton's law for a fairly general 5-D supersymmetric braneworld scenario with a bulk scalar field $\phi$. We show that the Newtonian potential describing the gravitational interaction between two bodies localized on the visible brane picks up a non-trivial contribution at short distances that depends on the shape of the superpotential $W(\phi)$ of the theory. In particular, we compute this contribution for dilatonic braneworld scenarios $W(\phi) = e^{\alpha \phi}$ (where $\alpha$ is a constant) and discuss the particular case of 5-D Heterotic M-theory., Comment: Contribution to the Proceedings of the 13th International Symposium on Particles, Strings and Cosmology, PASCOS-07

WIMP models of cold dark matter which exhibit nearly degenerate excited states have a number of interesting signatures that may prove relevant for direct and indirect searches. Such near‐degeneracies form a qualitatively distinct regime in the parameter space of many models which, generically due to the little hierarchy problem, now require efficient co‐annihilation to ensure the correct relic density. This work discusses the relevance of such scenarios for explaining the observed galactic 511 keV line, and also the impact on direct terrestrial searches which may be complicated by recombination‐type processes.

In this talk, we will present recent progresses in perturbative calculations of scattering amplitudes at tree and one‐loop levels. At tree level, we will discuss MHV‐diagram method and on‐shell recursion relation. At one‐loop level, we will establish the framework of Unitarity cut method.

A minimal lepton number conserving extension to the Standard Model is considered providing light Dirac neutrinos without resorting to tiny Yukawa couplings. Successful baryogenesis through leptogenesis is not only possible in this case, but even suggests an electroweak scale vacuum expectation value for a gauge singlet scalar in the model. The spectrum contains two massive Higgs bosons and a massless Nambu‐Goldstone boson. The existence of the Nambu‐Goldstone boson suppresses the Higgs to bb branching ratio and instead Higgs bosons will decay mainly into invisible Goldstone bosons. We consider the constraints on the potential and the implications for the LHC.

Intersecting stacks of supersymmetric fractional branes on the Z6′ orientifold may be used to construct the supersymmetric Standard Model. We construct a four‐stack model, which has the matter spectrum of the supersymmetric Standard Model, including a single pair of Higgs doublets, plus three neutrino‐singlet states. However, the gauge group is SU(3)colour×SU(2)L×U(1)Y×U(1), and there is no overall cancellation of Ramond‐Ramond tadpoles

We review why detection of non‐Gaussianity in the spectrum of primordial fluctuations would be an indication of interesting inflationary physics and discuss the observational constraints on a simple type of scale‐dependent non‐Gaussianity. In particular, if the amount non‐Gaussianity increases during inflation then observations on scales smaller than those probed by the Cosmic Microwave Background may provide important constraints. Clusters number counts can be a useful tool in this context.

Upper bounds on the reheat temperature of the early universe, as they appear for example in classes of supergravity models, impose severe constraints on the thermal leptogenesis mechanism. To analyse these constraints, we extend the flavour‐dependent treatment of leptogenesis to include reheating. We solve the flavour‐dependent Boltzmann equations to obtain the leptogenesis efficiency as a function of the flavour dependent washout parameter m1,α and of mN1/TRH, the ratio of the mass of the lightest right‐handed neutrino over the reheat temperature, and calculate the minimal values of the reheat temperature compatible with thermal leptogenesis in type I and type II seesaw scenarios.

One of the most appealing questions in astroparticle physics concerns the nature of the Dark Matter (DM) particles and their possible interaction with ordinary matter. In order to find a solution to such problem, a double phase liquid‐gas Xenon Time Projection Chamber has been proposed and built as a suitable detector for the direct detection of DM in the form of Weakly Interacting Massive Particles (WIMPs). The possibility of simultaneously measuring the scintillation and the ionization signals, and a 3D event localization feature, represent a powerful background discrimination method. During the Autumn‐Winter 2006‐2007 a prototype of 15 kg sensitive mass of Liquid Xenon (XENON10) has been successfully run at the Gran Sasso Underground Laboratory. The technique and the results of the XENON10 detector are presented.

Previously it was shown that the presence of negative‐norm states or negative‐frequency solutions is indispensable for a fully covariant quantization (Krein space quantization) of the minimally coupled free scalar field in de Sitter spacetime. This new method of quantization has been extended to free boson and spinor fields in Minkowski spacetime. The presence of unphysical negative‐frequency states plays the role of an automatic renormalization tool for the theory.

We study the evolution of the universe which contains a multiple number of non‐relativistic scalar fields decaying into both radiation and pressureless matter. We present a powerful analytic formalism to calculate the matter and radiation curvature perturbations, and find that our analytic estimates agree with full numerical results within an error of less than one percent. Also we discuss the isocurvature perturbation between matter and radiation components, which may be detected by near future cosmological observations, and point out that it crucially depends on the branching ratio of the decay rate of the scalar fields and that it is hard to make any model independent predictions.