LBNL Physics Division Research Progress Meetings

Taylor Hoyt (University of Chicago) "Using Astrophysical Distance Indicators to Test Standard Cosmology"
2021-11-16 13:00 UTC | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
Measurements of the universe’s present-day expansion rate, or the Hubble constant (H0), that use a Cepheid variable star calibration of Type Ia supernovae (SNe Ia) are in >4σ disagreement with values predicted by the standard, Lambda cold dark matter (LCDM) model of the universe. In this talk, I will review the evidence for this “Hubble Tension” and discuss in particular my work on an alternative calibration of the SNe Ia using the Tip of the Red Giant Branch (TRGB), a standard candle that can return distances precise to 2% when observed in ancient populations of stars. Anchored by the TRGB, we derived in the Carnegie Chicago Hubble Program a SN value of H0 that is significantly less in tension with base LCDM (<2σ) than the Cepheid-calibrated SN H0, which raises the question of underestimated uncertainties and softens evidence for new physics. I will identify likely causes of this Cepheid-TRGB divergence, present paths to a potential resolution, and highlight how the astrophysical distance scale can converge on a self-consistent, 1% determ
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Prof. Rouven Essig (TBA) " Direct Detection of sub-GeV Dark Matter"
2017-05-11 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
Dark matter makes up 85% of the matter in our Universe, but we have yet to learn its identity. A broad array of search strategies are needed to probe for non-gravitational interactions between dark matter and ordinary matter. While most searches focus on Weakly Interacting Massive Particles (WIMPs) with masses between 1 GeV and 1 TeV, it is imperative to also consider other motivated dark matter candidates. In this talk, I will discuss dark matter with MeV-to-GeV masses, which is a theoretically and phenomenologically appealing possibility and presents a new frontier in the search for dark matter. I will highlight novel dark matter direct-detection strategies that can probe this under-explored mass range. I will review how XENON10 data already probes dark matter with masses as low as a few MeV, and present recent constraints using XENON100 data. I will then discuss improvements expected from near-future experiments, focusing on xenon, semiconductor, and scintillator targets. This includes, for example, SENSEI, which is a new ultra-low-threshold silicon CCD detector that is poised to probe vast new regions of parameter space in the next few years. I will also present a few simple benchmark models of MeV-to-GeV dark matter, and contrast direct-detection probes with searches at colliders and fixed-target experiments.

Manoj Kaplighat (UC, Irvine) "The self-interacting dark matter paradigm: motivations and tests"
2017-05-04 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
Abstract:

I will describe how a simple model where dark matter has large elastic self-interactions (cross section over mass of order barns per GeV) can fully explain the observed diversity of all galactic rotation curves. I will summarize the constraints imposed on model building by observations of clusters of galaxies and end with an outline of tests of this paradigm.

Heather Gray (LBNL) Title: The Art of the Impossible: Probing challenging Higgs channels at the LHC
2017-04-27 16:00 - 17:00 (America/Los_Angeles)
Abstract:

In the technical design report of the LHC experiments, measurements of the Higgs coupling to top and bottom quarks and the width of the Higgs were either predicted to be extremely challenging, if not impossible at the LHC. Yet, ATLAS and CMS have both produced interesting results for all these channels. I will highlight selected aspects of these measurements to discuss what allowed ATLAS and CMS to probe the “impossible“.

Director's Physics Division Review
2017-04-12 08:00 - 2017-04-13 17:00 (America/Los_Angeles)

Professor Sunil Golwala (Caltech) "The SuperCDMS SNOLAB Search for Low-Mass Dark Matter"
2017-03-30 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract
The dark matter problem, known since the 1930s, has only grown in importance during the current era of precision cosmology. We remain unable to answer the question: what is the matter that makes of 5/6 of the universe’s matter density? Yet we are also in an era of unparalleled theoretical creativity and experimental opportunity. Theorists have vastly expanded the parameter space for weakly interacting massive particle dark matter in the last decade. New experimental constraints and candidates have emerged from the LHC, other accelerator experiments, and direct and indirect detection dark matter searches. I will summarize the current state of experimental searches for particle dark matter and focus on the upcoming search at low mass with the SuperCDMS SNOLAB experiment.

Haichen Wang (LBNL) Title: Search for physics beyond the Standard Model using multijet events with the ATLAS detector at the LHC
2017-03-28 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
Abstract:
Search for physics beyond the Standard Model (SM) has been one of the most important goals of the physics program at CERN’s Large Hadron Collider (LHC). Among all the final states, the multijet final state has long been considered as a challenging one for the search of physics beyond the SM due to its large background. Though, exciting new physics phenomena, such as the production of black hole as well as massive supersymmetric (SUSY) particles, may well result in signals in the multijet final state. I present searches for physics beyond the SM using multijet events from 13 TeV collision data taken in 2015 and the first half of 2016 by the ATLAS experiment at the LHC. I focus on a search for the production of black hole and a search for massive supersymmetric particles decaying to many jets via R-Parity Violating (RPV) couplings. The two examples represent searches targeting physics beyond the SM at different mass scales, and therefore different analysis strategies are employed. These searches have greatly improved the sensitivity of the LHC to the black hole production and RPV SUSY scenarios, and they are complementary to searches using events of leptons, photons and missing transverse energy.

Megan Eckart (NASA) "X-ray Astrophysics Enabled by Microcalorimeters: from Recent Observations to Next-Generation Technologies"
2017-03-23 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
High-resolution imaging spectroscopy in the soft x-ray waveband (0.1-10 keV) is an essential tool for probing the physics of the x-ray universe. Unique line diagnostics available in this waveband allow transformative scientific observations of a wide array of sources. For example, measurements of turbulence in the intra-cluster medium of galaxy clusters can be used to calibrate hydrodynamic simulations used in cosmology; and measurements of outflow processes from supermassive black holes may identify the key mechanism that regulates the co-evolution of host galaxies and their central black holes. I will introduce the microcalorimeter, a low-temperature detector capable of x-ray photon counting with high spectral resolution, and discuss observations of the Perseus Cluster made using our microcalorimeter instrument that launched aboard the Japanese-led Hitomi (Astro-H) mission in 2016. I will discuss our recent advances using transition-edge-sensor (TES) microcalorimeters and identify areas in detector, readout, and instrument development that are needed for next-generation instrumentation for space- and laboratory-based experiments. Techniques and challenges will be compared to those of envisaged cryogenic CMB and direct dark matter detection experiments.

Roger O’Brient (JPL) “The Search for Inflationary Gravitational Waves: Current Status of the BICEP Program and Next Generation Instrumentation.”
2017-03-21 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
For over a decade, the BICEP collaboration has been deploying small aperture telescopes to the South Pole Station to map B-mode polarization in the Cosmic Microwave Background and
search for evidence of primordial gravitational waves. If detected, they would allow physicists
to constrain physics at energy scales of ~10 16 GeV levels. To date, this program places the
tightest constrains on the tensor-scalar ratio of r<0.07 (95% confidence). We are at an
important point in our program as we transition into “Stage-3” instruments with the BICEP-
array, which will search to a level of r>0.01. This rapid progress is fueled by the antenna-
coupled superconducting bolometers that we have developed at NASA’s Jet Propulsion
Laboratory. In my talk, I’ll summarize the science case for these experiments, describe the
instruments themselves with a focus on the detectors, discuss the recently collected data, and
comment on the future of our program. In particular, Thermal KIDs, an emerging bolometer
technology, will be critical for this next phase. Finally, I’ll comment on how LBL and DOE can
and will play a future role in this exciting frontier of fundamental physics.

Prof. Stacy McGaugh (Case Western) "The Radial Acceleration Relation in Rotationally Supported Galaxies"
2017-03-16 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
ABSTRACT:
We report a correlation between the radial acceleration traced by rotation curves and that predicted by the observed distribution of baryons. The same relation is followed by 2693 points in 153 galaxies with very different morphologies, masses, sizes, and gas fractions. The correlation persists even when dark matter dominates. Consequently, the dark matter contribution is fully specified by that of the baryons. The observed scatter is small and largely dominated by observational uncertainties. This radial acceleration relation is tantamount to a natural law for rotating galaxies.

Timon Heim (LBNL) “Challenges of the ATLAS Phase 2 Tracker Upgrade”
2017-03-09 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
For the phase 2 upgrade of the ATLAS experiment at the LHC, its inner detector will be replaced by a new all-silicon tracker, the Inner Tracker (ITk). This upgrade is necessary both because the inner detector will have reached its intended lifetime and to maintain tracking performance of the ATLAS detector under the demands of a 5 to 7 times higher collision rate after the high luminosity upgrade of the LHC. This presentation will give an overview and status of the ITk Strip and Pixel detector. It will highlight one major challenge for each of the detectors: the on-module DC-DC powering circuit of the ITk Strip detector and the 65nm readout chip of the ITk Pixel detector. Furthermore I will present a readout concept which could be used as a base for a common ITk readout software core. This core can operate with multiple hardware platforms and user interfaces, an essential feature for the successful transition from prototyping and production to detector commissioning and operation.

Elisabetta Pianori (CERN) "Unveiliing the Origin of Particles' Mass: Higgs Boson Coupling Measurements at the LHC"
2017-03-07 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
Although the Standard Model (SM) of particle physics is a very successful theory, it fails to explain the origin of particles’ mass. If the Higgs mechanism, developed in the 60s as a solution to this puzzle, is the correct theory of Nature, a new fundamental particle, the Higgs boson, must exist. In 2012, at the LHC, a particle consistent with the Higgs boson was discovered. The theory prescribes the strength of the Higgs boson interaction with SM particles, but physics beyond the Standard Model could modify it. In this talk I will present the evidence of direct couplings of the Higgs boson to fermions and compare them with the predictions. I will also discuss the ATLAS+CMS combined measurement of the Higgs boson production and decay rates, and how they constrains the Higgs boson’s couplings to SM particles and the existence of new physics.

Javier Tiffenberg (Fermilab) "Things to do with less than one electron: the dawn of the ultimate ionization detector"
2017-03-02 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:

Silicon charged coupled devices (CCDs) have proven to be exceptional for the detection and measurement of photons and other ionizing radiation. Their low energy threshold of 50eV (~14 e-) have made them ideal for astronomical aplications and for detectors exploring Neutrino interactions (CONNIE) and searching for Dark Matter particles (DAMIC). However, the counting of individual photons and energy depositions below 50 eV has proven difficult due to an inability to reduce electronic noise below the level of a single charge carrier. Here I’ll present the results of a collaboration between Fermilab and LBL to build a Sub-Electron Noise Skipper Experimental Instrument (SENSEI) which uses a non-destructive readout technique to achieve stable readout for a thick fully depleted silicon CCD in the far sub-electron regime (∼ 0.05 e − rms/pix). This is the first time that discrete sub-electron counting has been achieved reproducibly over millions of pixels on a stable, large-area detector (7 cm^2 ) with large dynamic range. This innovative technology has nearly immediate implications for a wide range of scientific disciplines including astronomy and fundamental particle physics.

slides: pdf

Yun-Tse Tsai (SLAC/Stanford) "Exploring ν Territory: Using LArTPC Technology ("ν“ here is a Greek alphabet accounting for neutrinos)"
2017-02-28 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:

The discovery of neutrino oscillation, which implies neutrinos have non-zero masses, is the first instance of a conflict with the Standard Model of particle physics. The fruitful results from neutrino experiments in the past two decades have opened a window into a new territory, where the unanswered questions in the current theory, such as the observed matter-antimatter asymmetry, may be addressed by the upcoming precision measurements.
In this talk, I will introduce the core topics of neutrino physics and the requirements of neutrino experiments, focusing on the technology of liquid argon time projection chamber (LArTPC). The outstanding spatial and energy resolution of LArTPC provides us with a promising apparatus for the required precision. In particular, I will discuss detection of neutrinos from supernova explosions, and searches for other weakly interacting particles as well as rare physics processes. I will talk about the MicroBooNE experiment, the first large LArTPC in the U.S., its recent results, and the future LArTPC experiments.

Alvaro Chavarria (U. Chicago) “Solid-State Imaging Detectors for Low-Energy Particle Physics”
2017-02-23 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
The low noise, high spatial resolution and reliable performance of charge-coupled devices (CCDs) and complementary metal-oxide-semiconductor (CMOS) active-pixel sensors have made them detectors of choice for digital imaging. Although the slow time response of these devices has limited their application in high-energy particle physics, for the case of rare-event searches, where the particle interaction rate is extremely low, their properties can be fully exploited to build detectors that outperform in many aspects the traditional technologies of the field. I will present recent results from the DAMIC experiment, a low-mass dark matter search consisting of low-noise CCDs deployed in the SNOLAB laboratory. I will show how the exquisite spatial resolution of the detector allows for particle identification, and provides the unique capability to reject sequences of radioactive decay with utmost efficiency. These techniques can be extended to the search for neutrinoless double beta decay. I will present a recent proposal where we argue that a large array of amorphous Se-82 imagers based on CMOS technology could achieve the background levels necessary to test if neutrinos are Majorana fermions even in the case of a normal hierarchy of neutrino masses.

Stefano Camarda (CERN) "Electroweak precision physics at the LHC"
2017-02-21 16:00 - 17:00 (America/Los_Angeles)
Abstract:
Precision measurements of electroweak observables offer a viable
option for finding indications of new physics and also guidance for
the next big discovery. In this talk, I will focus on the latest
electroweak precision measurements at the LHC, with an emphasis on the
W-boson mass measurement recently published by ATLAS. The evaluation
of the experimental systematic uncertainties, as well as the
uncertainties due to the modeling of the vector boson production and
decay of the ATLAS W-boson mass measurement will be discussed.
In addition, the LHC results will be put in context to previous
measurements at the Tevatron and LEP colliders.

Aritoki Suzuki (UCB) "Next Generation Cosmic Microwave Background Polarimetry Experiment - Enabling Technologies for an Order of Magnitude Increase in Detector Count"
2017-02-16 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Precision measurements of Cosmic Microwave Background (CMB) temperature anisotropies over the last two decades have been a spectacular success, constraining all six parameters of the LambdaCDM cosmological model to the percent level. However, while CMB temperature is well explored, current experiments are just now becoming sensitive enough to explore the rich physics of CMB polarization.
“Stage-II” CMB experiments started to deploy in early 2010’s, contain ~1,000 millimeter-wave, polarization-sensitive detectors, and have discovered B-mode polarization due to weak gravitational lensing and set limits on B-modes due to inflationary gravitational waves. “Stage-III” experiments have begun to deploy this year and contain ~10,000 detectors for an order-of-magnitude improvement in sensitivity.
Looking to the future, the CMB community has begun studying “CMB-S4”, a “Stage-IV” experiment that will contain ~500,000 detectors, a factor ~100 increase over experiments currently in the field. The goal of CMB-S4 is to make a definitive measurement of CMB polarization from the ground in order to explore inflationary scenarios, constrain the sum of the neutrino masses, and search for new physics within the early universe.
During this presentation, I will discuss the exciting science objectives of modern CMB experiments, the tremendous technological challenge of fielding large numbers of highly-sensitive detector arrays, and the advancement in technologies we are developing to overcome these challenges to conduct the ultimate CMB polarization measurement.

Manuel Franco Sevilla (UCSB) "Strategies for Searches of Physics Beyond the Standard Model in the XXI Century"
2017-02-14 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
ABSTRACT:

At the end of the XIX century, Lord Kelvin summarized a widespread feeling among physicists by saying that “physics is essentially complete, save for two little clouds”. The “clouds” he was referring to were the puzzling results from two measurements, the Michelson-Morley experiment and the Black-body spectrum, whose explanations ushered in an unprecedented era of discoveries that stretched throughout most of the XX century. After the culmination of the Standard Model in the 70’s, the field of particle physics has found itself in a similar situation. Today, the “clouds” guiding the searches for physics beyond the Standard Model are issues like dark matter or the hierarchy problem. Using SUSY searches at CMS and the measurement of B->D(*)TauNu decays at BaBar as models, I will give an overview of some of the main strategies that are being followed in the quest to find new physics in the XXI century.

Peter Sorensen (LBNL) "How to See Dark Photons: A Status Report on a New Avenue in Direct Detection"
2017-02-09 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
I will discuss the new (old) idea that dark matter may reside in a hidden sector whose interactions with the standard model are mediated by a dark photon. Possibilities for direct detection of such particles will be discussed. This is particularly timely given the recent DOE call for a small scale direct detection experiment that can search new parameter space.
20170209_RPM slides

Reserved
2017-02-07 16:00 - 17:00, 2017-02-02 16:00 - 17:00, 2017-01-31 16:00 - 17:00, 2017-01-26 16:00 - 17:00, 2017-01-24 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720

Kirit Karkare (Harvard) "B-Mode Polarization Results from BICEP/Keck Array and Beam Systematics in Current and Next-Generation CMB Experiments"
2017-01-19 16:00 - 17:00 (America/Los_Angeles)
Abstract:
The BICEP/Keck Array cosmic microwave background (CMB) polarization experiments located at the South Pole are a series of small-aperture refracting telescopes focused on the degree-scale B-mode signature of inflationary gravitational waves. I will present our latest results which have produced the most stringent constraints on the tensor-to-scalar ratio to date: sigma(r) = 0.024 and r < 0.09 from B-modes alone (r < 0.07 in combination with other datasets). These constraints will rapidly improve with upcoming measurements at the multiple frequencies needed to separate Galactic foregrounds from the CMB, and in combination with higher-resolution experiments to remove B-modes induced by gravitational lensing. I will provide an update on our expanded frequency coverage and plans for future receivers.
Next-generation CMB experiments with hundreds of thousands of detectors will require exquisite control of instrumental systematics. I will review key aspects of the BICEP/Keck instrument design which maximize polarization sensitivity and reduce systematics at large angular scales, including the ability to measure beams in the far field with high precision. Finally, I will discuss the prospects for dealing with temperature-to-polarization leakage in future experiments, and how the beams systematics levels we achieve with current instrument and analysis technology will scale with detector count.

Aleksandra Dimitrievska (U. Belgrade) "Measurement of the W-boson mass with the ATLAS detector "
2017-01-17 16:00 - 17:00 (America/Los_Angeles)
Abstract:
The precise measurements of the W boson, the Higgs boson and the top quark masses enables to test the consistency of the Standard Model. Constraints on physics beyond the Standard Model are currently limited by the precision of the W-boson mass measurement. In this talk a measurement of the W-boson mass is presented with the data collected in 2011 at centre-of-mass energy of 7 TeV with the ALTAS detector corresponding to an integrated luminosity of 4.6 fb⁻¹. The measurement is based on about 8 and 6 million W candidates in the muon and electron channels, respectively. The W-boson mass is extracted from the template fits to the transverse momentum of the charged lepton and to the transverse mass of the W boson distributions. This measurement yields a W-boson mass:
mW = 80370 ± 7 (stat.) ± 11 (exp. syst.) ± 14 (mod. syst.) MeV = 80370 ± 19 MeV,
where the first uncertainty is statistical, the second corresponds to the experimental systematic uncertainty, and the third to the physics-modelling systematic uncertainty.

Siyuan Sun (Harvard) "Gaining Sensitivity to New Physics with a Compressed Mass Spectra at the ATLAS Experiment"
2017-01-12 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
ABSTRACT
The ATLAS experiment at Large Hadron Collider (LHC) searches for experimental ev-
idence of many new beyond the standard model physics at the TeV scale. As we collect
more data at the LHC we continue to extend our sensitivity to these new phenomenon,
particularly probing increasingly more massive new particles. Despite this progress there
are still regions of parameter space where constraints remain weak. One common cause of
this lack of sensitivity is because the new particle has a very small mass splitting between it
and its decay products. The particle then has little energy left over to give momenta to its
decay products and the low momenta decay products are difficult to experimentally detect.
These regions of small mass splitting are called compressed regions. We are able to gain
sensitivity to these difficult regions by searching for new particles produced in conjunction
with strong initial state radiation (ISR). The strong initial state radiation boosts the new
particle’s decay products and gives them momentum.
In this seminar, I will cover in detail the search for the supersymmetric partner to the
top quark (stop) in the region when the stop and its decay products are nearly degenerate in
mass. No searches prior to 2016 was sensitive to this region. We were able to exclude stops
up to a mass of 425 GeV in this region with the 2015 and summer 2016 ATLAS dataset. I will
demonstrate a new and more accurate technique for identifying whole initial state radiation
systems instead of a single ISR jet. As the LHC provides more data and traditional search
methods rule out parameter space at higher masses, it becomes more important that we also
gain sensitivity to these compressed regions that are still unconstrained at low masses. I will
show that this initial state radiation identification technique is completely generalizable and
useful for many other searches that target small mass splittings.

Michael James Wilson (Institute of Astronomy, U. Edinburgh) "Extracting precision tests of gravity from the intricate pattern of galaxies"
2017-01-10 16:00 - 17:00 (America/Los_Angeles) | 50A-4133 (Director's Conference Room)
ABSTRACT:
Galaxy redshift surveys deliver increasingly precise tests of gravity on cosmological scales and shed light on the uncertain nature of Dark Energy. I will present the VIPERS (http://vipers.inaf.it) census of the galaxy distribution at redshift 0.8 and describe its consistency with the expansion history and rate of gravitational collapse predicted by General Relativity and a Planck (2015) cosmology. This is facilitated by the anisotropy of the observed clustering, which is sensitive to both the coherent infall of galaxies towards clusters and the assumption of an expansion history differing from the true one.
I will then present the results of including a simple density transform prior to this conventional analysis, which suppresses the most massive structures and extends the validity of the simplest models. Moreover, this has been shown to amplify signatures of modified gravity in ‘shielded’ theories and contains information beyond that available to the power spectrum. To do so requires correcting for many systematics that are characteristic of high-redshift surveys. I will describe the properties common to VIPERS, eBOSS and DESI and the potential of a density-weighted analysis with these next-generation surveys.
Finally, tests of gravity have predominantly focused on the large-scale velocities of galaxies to date, but that of clusters is imprinted on the Cosmic Microwave Background by the kinetic Sunyaev-Zel’dovich effect. The Simons Observatory and CMB-S4 experiments represent ideal test-beds for exploring the latter. I will discuss this and other future avenues for revealing the properties of Dark Energy with large-scale structure.

Eleonora Di Valentino (Institut d'Astrophysique de Paris) "New Constraints on Extensions of the Standard Cosmological Model"
2017-01-05 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
The Cosmic Microwave Background (CMB) temperature and polarization anisotropy measurements from the Planck mission have significantly improved previous constraints on the neutrino masses, as well as the bounds on extended models with massive sterile neutrino states or extra particles, as for example thermal axions. In this talk firstly I will show the recent constraints from cosmology for the thermal axion mass and the neutrino sector, by considering several combination of datasets and scenarios. In particular, I will show how the inclusion of additional low redshift priors is mandatory in order to sharpen the CMB neutrino bounds, and that we are close to test the neutrino mass hierarchy with existing cosmological probes. Secondly, I will discuss how these constraints can change by taking into account the possibility that the primordial power spectrum could assume a more general shape than the usual power law description. Finally, I will present cosmological constraints in a significantly extended scenario, varying up to 12 cosmological parameters simultaneously, by looking for a new concordance model that should solve at the same time all the current tensions between the Planck data and the new direct measurements of the Hubble constant by Riess et al. 2016 and the parameters from weak lensing surveys, such as CFHTLenS and KiDS-450.

Zackay Barak (Weizmann Institute of Science) Algorithms for searching Fast radio bursts, pulsars in tight binary systems and "Planet 9"
2017-01-03 16:00 - 17:00 (America/Los_Angeles)
Abstract:
Fast radio bursts (FRB’s) are an exciting, recently discovered, astrophysical transients which their origins are unknown.
Currently, these bursts are believed to be coming from cosmological distances, potentially allowing us to probe the electron content on cosmological length scales. Even though their precise localization is crucial for the determination of their origin, radio interferometers were not extensively employed in searching for them due to computational limitations.
I will briefly present the Fast Dispersion Measure Transform (FDMT) algorithm, allowing to reduce the operation count in blind incoherent dedispersion by 2-3 orders of magnitude.
In addition, FDMT enables to probe the unexplored domain of sub-microsecond astrophysical pulses.Pulsars in tight binary systems are among the most important astrophysical objects as they provide us our best tests of general relativity in the strong field regime.
I will provide a preview to a novel algorithm that enables the detection of pulsars in short binary systems using observation times longer than an orbital period.
Current pulsar search programs limit their searches for integration times shorter than a few percents of the orbital period.
Until now, searching for pulsars in binary systems using observation times longer than an orbital period was considered impossible as one has to blindly enumerate all options for the Keplerian parameters, the pulsar rotation period, and the unknown DM.
Using the current state of the art pulsar search techniques and all computers on the earth, such an enumeration would take longer than a Hubble time. I will demonstrate that using the new algorithm, (called Pruning) it is possible to conduct such an enumeration on a laptop using real data of the double pulsar, PSR J0737-3039.
Among the other (astronomical) applications of the Pruning technique are:
1) Searching for all pulsars on all sky positions in gamma ray observations of the Fermi LAT satellite.
2) Blind searching for continuous gravitational wave sources emitted by pulsars with non-axis-symmetric matter distribution.

3) Blind searching for planets in the outskirts of the solar system (AKA “Planet 9”), both in imaging data and on GAIA data (through astrometric deflection of background stars).

4) Blind searching for asteroids and Kuiper belt objects in imaging data.

5) Searching for stars in close orbits around the super massive black hole in the galactic center.

Previous attempts to conduct all of the above searches (if even considered) contained substantial sensitivity compromises.
