CosPA 2016

28 Nov 2016, 08:00 → 2 Dec 2016, 14:00 Australia/Sydney

Archil Kobakhidze (The University of Sydney), Gary Hill (University of Wisconsin, Madison), Geraint Lewis (The University of Sydney), Jan Hamann, Kevin Varvell (The University of Sydney), Michael Schmidt (The University of Sydney), Yvonne Wong (The University of New South Wales)

The 13th International Symposium on Cosmology and Particle Astrophysics (CosPA 2016) will be hosted by the University of Sydney from November 28 to December 2, 2016 at the Sydney Nanoscience Hub, located on the University's Camperdown Campus.

CosPA 2016 will bring together theorists, experimentalists, and observers working in the fields of particle physics, cosmology, and astrophysics to discuss the latest results and ideas, and prospects for progress.

The conference will feature invited plenary talks covering topics of recent interest. A number of parallel sessions will provide an opportunity for junior scientists to present their work.

We look forward to seeing you in Sydney.

 

Plenary speakers include:

Jenni Adams (U. Canterbury)	IceCube
Elisabetta Barberio (U. Melbourne)	SABRE
Jose Bellido (U. Adelaide)	Pierre Auger Observatory
Regina Caputo (UC Santa Cruz)	Fermi LAT
Roland Crocker (ANU)	Galactic positron population
Tamara Davis (U. Queensland)	Dark Energy with the Dark Energy Survey
Silvia Galli (IAP Paris)	Planck CMB results
Paolo Gondolo (U. Utah)	Dark matter theory
Clancy James (Erlangen-Nürnberg)	ANTARES/KM3NeT
Jihn E. Kim (Kyung Hee U.)	Axions
Chia-Ming Kuo (National Central U.)	Invisible Higgs decays, SUSY searches and BSM Higgs at the LHC
Alexander Kusenko (UCLA)	Baryo-/Leptogenesis
Geraint Lewis (U. Sydney)	Cosmological surveys
Eric Linder (UC Berkeley)	Dark energy
Manfred Lindner (MPIK Heidelberg)	Dark matter direct detection
David McClelland (ANU)	Gravitational waves
Millie McDonald (U. Melbourne)	Mono-X, dijet, and long-lived particle searches at the LHC
Mercedes Paniccia (Geneva U.)	AMS
David Parkinson (U. Queensland)	Tests of modified gravity
Lisa Randall (Harvard U.)	Darkly-Charged Dark Matter
Gavin Rowell (U. Adelaide)	The Cherenkov Telescope Array: A TeV Gamma-Ray Observatory
Misao Sasaki (Kyoto U.)	Inflation
Pat Scott (Imperial College London)	Astroparticle tests of dark matter theories
Arman Shafieloo (KASI Daejeon)	Consistency checks of LCDM
Shinji Tsujikawa (Tokyo U. of Sci.)	Theories of modified gravity
Raymond Volkas (U. Melbourne)	Outlook for the discovery of new physics
Wei Wang (Sun Yat-sen U.)	Neutrino experiments
David Wiltshire (U. Canterbury)	Inhomogeneous cosmology
Tsutomu Yanagida (U. Tokyo)	Neutrino mass in the landscape of vacua

 

Important reminder: All foreign visitors must obtain a valid visa before travelling to Australia!  Please make the necessary arrangements well ahead of time.

 

 

Business_Events_Information_Sheet_-_01_July_2015.pdf

CampusMap.pdf

DinnerVenue.pdf

InfoCosPA2016.pdf

timetable.pdf

Visa_Application_Requirements_Information_Sheet_-_July_2015_-_Business_Events.pdf

Monday 28 November

Registration

Plenary

Convener: Jisuke Kubo (Kanazawa University)

HouskeepingCosPA_v2.pdf

HouskeepingCosPA_v2.pptx

1 Opening Address

2 Gravitational waves

Speaker: Prof. David McClelland (ANU)

3 Theories of modified gravity

Speaker: Shinji Tsujikawa (Tokyo University of Science)

4 Tests of modified gravity

Speaker: Dr David Parkinson (University of Queensland)

CosPA_parkinson_Nov_16.pdf

10:30 Coffee Break

Plenary

Convener: Jun'ichi Yokoyama (The University of Tokyo)

HouskeepingCosPA_v2.pdf

HouskeepingCosPA_v2.pptx

5 Neutrino experiments

Speaker: Prof. Wei Wang (Sun Yat-Sen University)

NeutrinoExperiments_WeiWang_CosPA2016.pdf

6 Neutrino mass in the landscape of vacua

Speaker: Prof. Tsutomu Yanagida (University of Tokyo)

Neutrino mass Cospa.pdf

7 CPs and Type-II Leptogenesis

Speaker: Jihn E. Kim (Kyung Hee University)

CosPA16.pdf

12:30 Lunch

Cosmic microwave background and Large Scale Structure

Convener: Jan Hamann

8 New Measurements of CMB Polarisation from SPTpol

Measurements of the polarisation of the cosmic microwave background (CMB) are rapidly becoming an important tool to test the standard model of cosmology. In particular, searches for the faint CMB B-mode signals offer the prospect of detecting inflationary gravitational waves on large angular scales and mapping out the large scale distribution of matter in the Universe through CMB lensing on smaller angular scales. SPTpol is a CMB polarisation experiment located at the South Pole that has been pursuing both goals since 2012. I present the latest polarisation power spectra from SPTpol and discuss their cosmological implications. I will also say a few words about a new and dramatically improved CMB polarisation experiment, SPT-3G, which is slated for first light this January.

Speaker: Dr Christian Reichardt (University of Melbourne)

20161128_cospa_Reichardt.pdf

9 First detection of Galaxy Cluster lensing in CMB polarisation

Galaxy clusters are the largest gravitationally bound objects in the Universe and provide crucial insight to the standard model of cosmology. The abundance of these as a function of mass and redshift is highly sensitive to the cosmological parameters such as amplitude of matter fluctuations and dark energy equation of state parameter.

While galaxy clusters yield tremendously powerful tests of dark energy, their cosmological constraints are currently limited by a ~15% mass uncertainty. Future surveys like LSST and eROSITA will build ever larger cluster samples; our ability to fully realise the potential of these samples depends on better mass estimates. Gravitational lensing is widely considered the gold standard in mass estimation.
The next suite of Cosmic Microwave Background (CMB) polarisation experiments are expected to be able to normalise cluster masses to ~3% (a fivefold improvement!) by looking at the gravitational lensing signal in CMB polarisation. In this talk we present first ever lensing measurement of galaxy cluster mass using CMB polarisation data. We take data from the current SPTpol experiment, and use a maximum likelihood approach to extract the CMB cluster lensing signal from a catalog of Sunyaev-Zel’dovich effect selected galaxy clusters. We consider several sources of potential systematic error, and quantify their effect using mock data.

Speaker: Sanjaykumar Patil (University of Melbourne)

cospa_2016.pdf

10 Cosmology from CMB Polarization with POLARBEAR and the Simons Array

POLARBEAR is a cosmic microwave background (CMB) polarization experiment located in the Atacama desert in Chile. The science goals of the POLARBEAR project are to do a deep search for CMB B-mode polarization created by inflationary gravitational waves, as well as characterize the CMB B-mode signal from gravitational lensing. POLARBEAR-1 started observations in 2012, and in 2014, the POLARBEAR team published results from its first season of observations on a small fraction of the sky. These results include the first measurement of a non-zero B-mode polarization angular power spectrum, measured at sub-degree scales where the dominant signal is gravitational lensing of the CMB. To improve on these measurements, POLARBEAR is expanding to include an additional two telescopes with multi-chroic receivers, known as the Simons Array. With high sensitivity and large sky coverage, the Simons Array will create a detailed survey of B-mode polarization, and its spectral information will be used to extract the CMB signal from astrophysical foregrounds. We present the status of this funded instrument and its expected capabilities.

Speaker: Darcy Barron

Barron_Cospa_Nov2016.pdf

11 Planck large scale polarization

We investigate constraints on cosmic reionization extracted from the Planck cosmic microwave background (CMB) data. We combine the Planck CMB anisotropy data in temperature with the low-multipole polarization data to fit ΛCDM models with various parameterizations of the reionization history. We obtain a Thomson optical depth τ = 0.058 ± 0.012 for the commonly adopted instantaneous reionization model. This confirms, with data solely from CMB anisotropies, the low value suggested by combining Planck 2015 results with other data sets and also reduces the uncertainties.

We reconstruct the history of the ionization fraction using either a symmetric or an asymmetric model for the transition between the neutral and ionized phases. To determine better constraints on the duration of the reionization process, we also make use of measurements of the amplitude of the kinetic Sunyaev-Zeldovich (kSZ) effect using additional information from the high resolution Atacama Cosmology Telescope and South Pole Telescope experiments. The average redshift at which reionization occurs is found to lie between z = 7.8 and 8.8, depending on the model of reionization adopted. Using kSZ constraints and a redshift-symmetric reionization model, we find an upper limit to the width of the reionization period of ∆z < 2.8. In all cases, we find that the Universe is ionized at less than the 10 % level at redshifts above z ≃ 10. This suggests that an early onset of reionization is strongly disfavoured by the Planck data. We show that this result also reduces the tension between CMB-based analyses and constraints from other astrophysical sources.

Speaker: Dr Matthieu TRISTRAM (CNRS)

CosPA PLANCK large scale polarization.pdf

12 Oscillations in the CMB angular power spectra at ell~120

Cosmic Microwave Background (CMB) has been well known as a proof of the hot
big bang model. In recent years, thanks to the precise observations by WMAP
and PLANCK satellites, we come to see the detailed structure of CMB
temperature (or polarization) fluctuations. In this work, we forces on the
irregular oscillations of their angular power spectra around multipole
$\ell\sim120$. These oscillations were indicated in the analysis of WMAP5 data by
Ichiki et al. (2010). We look for these oscillations in the 2015 year's PLANCK
temperature and polarization data by adopting a Markov-Chain Monte-Carlo
(MCMC) method. We find the oscillations in the data at $\ell \sim 123.7$ and their
amplitude is about $4.5\times10^{-9}$, which are consistent with those found in the
WMAP5 data. In this presentation, we talk about the result of the MCMC
analysis and the influence of the oscillations to the other cosmological
parameters.

Speaker: Kouichirou Horiguchi (Nagoya University)

cospa20161128horiguchi.pdf

Dark matter

Convener: Victor Flambaum (University of New South Wales)

13 Dark matter searches in LUX

The Large Underground Xenon (LUX) is a dark matter experiment searching for direct evidence of Weakly Interacting Massive
Particles (WIMPs), a favored dark matter candidate. It is a 250 kg active mass dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility in USA. The results from the second and final science run with a total of 332 live days of exposure revealed no evidence of WIMP nuclear recoils with a four-fold improvement
in sensitivity for high WIMP masses relative to our previous results. Currently, LUX has the world leading exclusion limit in a wide range of WIMP masses. At a WIMP mass of 50 GeV c−2, WIMP-nucleon spin-independent cross sections above 0.22 zepto barns are excluded at 90%.

The interpretation of any potential WIMP signal requires to understand very well the response of the detector to both electronic and nuclear recoils thus requiring the LUX detector to be calibrated thoroughly during the second science run. ${}^{83m}$Kr was injected weakly, CH$_{3}$T, injected 2-3 times per year, used to define our elecronic recoil band and a collimated beam of monoenergetic 2.45 MeV neutrons used to define our nuclear recoil band. These calibrations were also essential to study the uniformity of the electric field, to define the active region volume and to correct the signal dependence with the position of interaction.

The LUX detector is also able to explore other alternative Dark Matter scenarios, such as axion like particles (ALPs) or look for other type of signals such as annual modulation signals or solar axions. An update of some of those searches will be presented as well.

Speaker: Claudio Frederico Pascoal da Silva (LIP Coimbra)

20161128_ClaudioSilva_COSPA_V2.pdf

14 Status of COSINE experiment.

The COSINE experiment is a joint collaboration between the KIMS-NaI and the DM-Ice NaI(Tl) experiments to prove or refute DAMA/LIBRA's annual modulation result with the same NaI(Tl) crystals. The first phase of the experiment consisting of ~106 kg of NaI(Tl) crystals and ~2000 liters of liquid scintillator as an active veto has started at the Yangyang underground laboratory in Korea.The current status and future prospects of COSINE experiment will be presented.

Speaker: Pushparaj Adhikari (Sejong University)

CosPA2016_Pushpa.pdf

15 Indirect searches of TeV Dark Matter at the Galactic Center

I will discuss several aspects of the indirect search of Dark Matter (DM) at the Galactic Center (GC). I will show that the gamma-ray flux observed by HESS from the J1745-290 GC source is well fitted as the secondary gamma-rays photons generated from DM annihilating into Standard Model particles in combination with a simple power-law background. The model independent fits are performed for all the possible channels of annihilation. The best fits are obtained for WIMP masses above $\sim10$ TeV. They require an enhancement factor of $\sim 10^3$ and a background spectral index compatible with the Fermi-LAT data. I will investigate the possibility that the expected enhancement may be related with hydrodynamics in N-body simulation or a DM spike induced by the Super Massive Black Hole Sgr A*. I will also discuss the possibility that the generated DM spike could be related with the spatial tail detected in the gamma-ray signal by HESS II in 2015. These TeV DM masses are practically unconstrained by direct detection searches or colliders experiments, but they can be tested with the observations of other cosmic-rays.

Speaker: Viviana Gammaldi (SISSA)

Gammaldi_COSPA16_20m_talk_v1.pdf

16 First Results of the GPS.DM Observatory: Search for Dark Matter and Exotic Physics with Atomic Clocks and GPS Constellation

Despite the overwhelming cosmological evidence for the existence of dark matter, and the considerable effort of the scientific community over decades, there is no evidence for dark matter in terrestrial experiments.
The GPS.DM observatory uses the existing GPS constellation as a 50,000 km-aperture sensor array, analysing the satellite and terrestrial atomic clock data for exotic physics signatures. In particular, the collaboration searches for evidence of transient variations of fundamental constants correlated with the Earth's galactic motion through the dark matter halo. There already exists more than 10 years of good clock timing data that can be used in the search.
This type of search is particularly sensitive to exotic forms of dark matter, such as topological defects.
We will present an update on the search.

*Supported by the NSF

A. Derevianko and M. Pospelov, Nat. Phys. 10, 933 (2014).

Speaker: Benjamin Roberts (University of New South Wales)

Roberts-GPSDMtalk 20161128-GPSdm-COSPA.pdf DMWallAnimation-PhaseShiftVersion.avi

17 Improved constraints on annihilating dark matter from cosmic-ray antiprotons

Local measurements of Galactic cosmic-ray antiprotons are known to provide constraints on the properties of annihilating cold dark matter (CDM). It is also known that CDM candidates generically lead to the structuring of matter on scales much smaller than typical galaxies. This clustering translates into a very large population of subhalos in galaxies, which induces an enhancement of the average annihilation rate with respect to a smooth-halo assumption. Taking these subhalos into account, and using measurements by the PAMELA and AMS-02 experiments, we derive new stringent constraints on annihilating CDM candidates.

Speaker: Martin Stref (Montpellier University)

CosPA16_Stref.mini.pdf

Gravity and gravitational waves

Convener: Rohana Wijewardhana

18 Tensor perturbations in spatially covariant gravity

We investigate the cosmological background evolution and perturbations in a
general class of spatially covariant theories of gravity, which propagates two tensor modes and
one scalar mode. We show that the structure of the theory is preserved under the disformal
transformation. We also evaluate the primordial spectra for both the gravitational waves and
the curvature perturbation, which are invariant under the disformal transformation. Due to
the existence of higher spatial derivatives, the quadratic Lagrangian for the tensor modes
itself cannot be transformed to the form in the Einstein frame. Nevertheless, there exists a
one-parameter family of frames in which the spectrum of the gravitational waves takes the
standard form in the Einstein frame.

Speaker: Jun'ichi Yokoyama (The University of Tokyo)

YokoyamaCosPA2016.pptx

19 Exploring a stochastic background of gravitational waves

The recent detections of gravitational waves from coalescing binary black holes by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) suggest that a stochastic gravitational wave background may be detectable by advanced detectors running at their design sensitivity. Looking at results from searches for both isotropic and anisotropic stochastic backgrounds in Advanced LIGO's first observing run, we discuss the implications such a detection could have on studies of the early universe.

Speaker: Letizia Sammut (Monash University)

CosPA_28Nov2016.pdf

20 Constraining non-commutative space-time from GW150914

The gravitational wave signal GW150914, recently detected by LIGO and Virgo collaborations, is used to place a bound on the scale of quantum fuzziness of non-commutative space-time. We show that the leading non-commutative correction to the phase of the gravitational waves produced by a binary system appears at the 2nd order of the post-Newtonian expansion. This correction is proportional to $\Lambda^2 \equiv |\theta^{0i}|^2/(l_P t_P)^2$, where $\theta^{\mu \nu}$ is the antisymmetric tensor of non-commutativity. To comply with GW150914 data, we find that $\sqrt{\Lambda} < 3.5$, namely at the order of the Planck scale. This is the most stringent bound on non-commutative scale, exceeding the previous constraints from particle physics processes by $\sim 15$ orders of magnitude.

Speaker: Cyril Lagger (The University of Sydney)

lagger_CosPA_2016.pdf

21 Entropy of Horava-Lifshitz Blakholes

Ever since the observation of Bekenstein that not only black hole mechanics can be given the form of the laws of thermodynamics, with area of horizon playing the role of
entropy, the surface gravity of temperature and the mass of the black hole as energy, the study of black hole thermodynamics has been a very active area of research due to fundamental problems posed by such a connection. Hawking’s discovery that black holes actually radiate via thermal spectrum gives credence to the idea that the connection between geometry and thermodynamical quantities is not incidental, rather reveals the underlying deep quantum structure of space-time as the entropy associated with a single classical solution must have a microscopic origin in more fundamental degrees of freedom.

Speaker: Dr shabana nisar (COMSATS Lahore)

cospa2016_australia_nisar-final.pdf

22 The quantum thermodynamic universe - an emergent perspective

The close connection between horizons (black hole event horizon, Rindler, de Sitter) and thermodynamics that has already been found can be extended here to a cosmological model, providing a new insight into the cosmological constant problem. The emergent nature of the field equations is interpreted as entropy balance condition of the spacetime. We describe various facets of the emergent gravity approach but concentrating on cosmological context. We discuss the thermodynamics of apparent horizons and derive Friedmann and Raychaudhuri equations from thermodynamical parameters.
If the gravitational field equations are indeed governed by thermodynamics and can be obtained by maximizing the entropy density of spacetime, as shown by Jacobson, it is also possible to go further and study the spacetime as emergent from the dynamics of entanglement in a general cosmological context.
In the paradigm introduced here, the entropy extremisation leads to the equilibrium properties of the Universe. Expansion parameters are found to emerge from the out-of-equilibrium difference between the number of degrees of freedom on the horizon surface and the bulk. The field equations, projected onto a null surface, reduce to Navier-Stokes equations. We study the expansion in terms of holographic equipartition that governs the evolution of spacetime geometry. The holographic principle proposes a deep connection between the degrees of freedom in a bulk region of space and the degrees of freedom on the boundary of the region. The dynamics of the large-scale structure of spacetime and the evolution of Friedmann universe are described as evolution towards a state of holographic equipartition, by reaching an equal number of bulk and surface degrees of freedom in a spacetime region within a Hubble radius. The vanishing of the cosmological constant is a consequence of an underlying symmetry of the theory. When this symmetry is broken, the cosmological constant is nonzero and arises at quantum level from degrees of freedom or microscopic spacetime fluctuations scaling as the surface area. The degrees of freedom are connected to surfaces in spacetime rather than the bulk region and play the most important role in understanding the quantum structure of spacetime. We find that a spacetime without the presence of a cosmological constant cannot reach the holographic equipartition. The dynamics of the asymptotic holographic equipartition will require the presence of a cosmological constant.

Speaker: Eric Howard (Macquarie University)

Particle astrophysics

Convener: Clancy James (University of Erlangen-Nuernberg)

23 Measuring the Leptonic Dirac CP Phase with Muon Decay at Rest

With the 1-3 mixing angle measured at reator neutrino experiments Daya Bay and RENO, there are still three unknown oscillation variables: the neutrino mass hierarchy, the octant of the atmospheric mixing angle, and the leptonic CP phase. Of these three, the CP phase is the most difficult to be measured precisely and important for distinguishing flavor symmetries. I will first review the status of CP measurement and then introduce a new proposal with muon decay at rest (muDAR). Currently, accelerator neutrino
experiments such as T2K, NOvA, and DUNE are the most promising for CP measurement. Nevertheless, they suffer from several problems of degeneracy, efficiency, sensitivity, and theoretical armbiguities such as non-unitarity mixing (NUM) and
non-standard interaction (NSI). The situation can be improved by adding a muon decay at rest (muDAR) source. With T2(H)K running
in neutrino mode and muDAR in anti-neutrino mode, both using the same detector, the CP measurement becomes more precise can break
the degeneracy between \delta and 180^o - \delta. Most importantly, muDAR can guarantee the CP sensitivity against NUM and NSI.
The same configuration can also apply to next-generation medium baseline reactor neutrino experiments like JUNO and RENO-50,
enhancing their physics potential from just mass hierarchy to also CP. With only one source and no extra detectors, this dessign
is much better than DAEdLAS which requires 3 sources, but only 20% duty factor and 4 times higher luminosity for each.

Speaker: Shao-Feng Ge (MPIK)

CosPA16_muDAR.pdf

24 Neutrino mass and hierarchy determinatiion from new physics

We present a detailed discussion on neutrinoless double beta decay within
a class of left-right symmetric models where neutrino mass originates by natural type II
seesaw dominance. The spontaneous symmetry breaking is implemented with doublets,
triplets and bidoublet scalars. The fermion sector is extended with an extra sterile neutrino
per generation that helps in implementing the seesaw mechanism. The presence of extra
particles in the model exactly cancels type-I seesaw and allows large value for Dirac neutrino
mass matrix $M_D$ . The key feature of this work is that all the physical masses and mixing
are expressed in terms of neutrino oscillation parameters and lightest neutrino mass thereby
facilitating to constrain light neutrino masses from neutrinoless double beta decay. With this large value of
$M_D$ new contributions arise due to; i) purely left-handed current via exchange of heavy
right-handed neutrinos as well as sterile neutrinos, ii) the so called $\lambda$ and $\eta$ diagrams. New
physics contributions also arise from right-handed currents with right-handed gauge boson
$W_R$ mass around 3 TeV. From the numerical study, we find that the new contributions to
neutrinoless double beta decay not only saturate the current experimental bound but also give lower limit on absolute scale of lightest neutrino mass and shows NH pattern of mass hierarchy is favorable..

Speaker: Prativa Pritimita (Siksha O Anusandhan University, Bhubaneswar, India)

cospa_sydney_talk.pdf

25 Measuring the Neutrino Mass Ordering with KM3NeT-ORCA

ORCA (Oscillations Research with Cosmics in the Abyss) is the low-energy branch of KM3NeT, the next generation underwater Cherenkov neutrino detector in the Mediterranean. Its primary goal is to resolve the long-standing unsolved question of whether the neutrino mass ordering is normal or inverted by measuring matter oscillation effects with atmospheric neutrinos. The ORCA design foresees a dense configuration of KM3NeT detection units, optimised for studying the interactions of neutrinos in seawater at low (< 100 GeV) energies. To be deployed at the French KM3NeT site, ORCA's multi-PMT optical modules will exploit the excellent optical properties of deep seawater to accurately reconstruct both cascade (mostly electron neutrinos) and track events (mostly muon neutrinos) with a few GeV of energy. This contribution reviews the methods and technology, and discusses the potentiality of the ORCA detector both in neutrino mass hierarchy studies and in obtaining new constraints on other key parameters such as $\theta_{23}$. Additional physics potentials will be mentioned.

Speaker: Antoine David Kouchner (Universite de Paris VII (FR))

ORCA_COSPA16_AK_final.pdf

26 Highlights of the ANTARES neutrino telescope results

The ANTARES experiment has been running in its final configuration since 2008. It is the largest neutrino telescope in the Northern hemisphere. A major goal of neutrino telescopes is the search for astrophysical neutrinos in the TeV-PeV range coming from resolved Galactic and extra Galactic sources or due to a diffuse cosmic neutrino flux.

In this kind of searches, a special role is played by the multimessenger approach. The search for time/space coincidence between neutrino telescope events and signals registered with other detectors increases the sensitivity of the analyses, significantly reducing the background. Interesting results have been obtained in collaboration with several different experiments sensitive on a wide range of the electromagnetic spectrum and, recently, limits have been set on the neutrino flux emitted with the gravitational waves event measured by the LIGO/VIRGO detectors on last September 15, 2015.

The discovery of a cosmic neutrino diffuse flux by the IceCube detector has made the search for its origin a key mission in high-energy astrophysics. Despite the reduced size, the ANTARES telescope is able to constrain the origin of the IceCube excess from regions extended up to 0.2 sr in the Southern sky. Though the golden channel for source searches is the identification of muons from charged current events of muon neutrinos, where angular resolution better than 1 degree can be obtained thanks to the excellent optical properties of the sea water, promising results have been obtained from the analysis of events with different topologies.

ANTARES has also provided results on atmospheric neutrinos, searches for rare particles (such as magnetic monopoles and nuclearites in the cosmic radiation), Dark Matter and Earth and Sea science.

A general survey of the most recent studies performed with ANTARES will be presented and discussed.

Speaker: Annarita Margiotta (Universita e INFN, Bologna (IT))

COSPA2016-Margiotta-ANTARES.pdf

27 Muon energy reconstruction in large-scale neutrino detectors

Understanding the properties of the astrophysical neutrino flux measured by IceCube relies upon the ability to reconstruct the energies of the muon events observed in the detector. In this talk, I will describe a maximum likelihood method that interprets the full pattern of reconstructed energy losses from each muon track to obtain a best estimate of the muon energy as the event entered the detector.

Speaker: Sally Robertson (University of Adelaide)

Edepillim_Sydney_2016.pdf

15:40 Coffee Break

Cosmic microwave background and Large Scale Structure

Convener: Luke Barnes

28 Distinguishing between Warm Dark Matter and Late Kinetic Decoupling using CMB spectral distortions.

Recently a number of alternative dark matter models have been introduced as a means of explaining the physics of small-scale structure formation. These include, warm dark matter and dark matter with late kinetic decoupling both of which differ substantially from the canonical cold dark matter formalism. One interesting way of constraining the phenomenology in these models is to look at the characteristic imprint they leave on the photon spectrum left over from the Big Bang. These imprints are known as spectral distortions in the literature and arise due to spatial fluctuations in the photon temperature along the line of sight. As a result, the thermal history of the photon bath gives us a unique insight into the evolution of the early universe. In this talk I will show how this insight can be used to constrain the phenomenology of these dark matter models, in particular noting that the signatures can be used to distinguish between warm dark matter and late kinetic decoupling scenarios.

Speaker: James Diacoumis (University of New South Wales)

CosPApres.key

29 Axion as a cold dark matter candidate: Proof to fully nonlinear perturbation

We present a proof of the axion as a cold dark matter candidate to the fully nonlinear and exact perturbations based on Einstein's gravity. We consider the axion as a coherently oscillating massive classical scalar field. We show that the axion has a characteristic pressure and anisotropic stress. But these terms do not affect the hydrodynamic equations in our axion treatment. The pressure term is negligible in the super-Jeans scale which is of the solar-system scale for conventional axion mass. As the fully nonlinear and relativistic hydrodynamic equations for an axion fluid coincide exactly with the ones of a zero-pressure fluid in the super-Jeans scale, we have proved the cold dark matter nature in that scale.

Speaker: Jai-chan Hwang

CosPA-axion-Hwang-20161128.pdf

30 Dark matter self annihilation in cosmological simulations

The standard model for the evolution of the universe is the Lambda cold dark matter (Λ-CDM) model. Its widespread acceptance is due to its simplicity and agreement with a whole host of different astronomical observations. However much is still unknown about the Dark Sector. While Λ-CDM successfully predicts the large scale properties of the universe, there are some discrepancies on the smaller scale, such as a larger than expected number of dwarf galaxies orbiting their parent galaxies and an over-abundance of dark matter in the cores of galaxies. While some have proposed these anomalies can be explained by baryonic physics or observational errors, there is still room for explanations lying within the Dark Sector.

In this presentation, I will show n-body simulations (based on Gadget 2) of simple model halos with gas components in which dark matter undergoes WIMP-like self-annihilation. This annihilation causes a mass loss of the dark matter components and the corresponding energy released by these interactions feed into the surrounding gas particles, affecting the mass distribution these of these halos. By developing this simple model and implementing it into sophisticated cosmological simulations, we will determine how these interactions imprint indirect clues onto the large and small scale galactic structure as to the identity and effect of dark matter on the universe.

Speaker: Nikolas Iwanus (University of Sydney)

31 Unveiling the Signatures of an Evolving and Interacting Dark Sector

Using state of the art numerical simulations, I have unravelled observational signatures of several alternative cosmological models in the large-scale structure of the cosmic web. The key observational probe under study is evolution of cosmological voids, to provide us with clues to the underlying cosmology of the Universe. While the ultimate goal will be to include galaxy formation recipes to determine the true efficacy of using cosmic voids in realistic future surveys with the next generation of ground- and space-based telescopes, in this presentation I will reveal how the size, shapes and density of voids, and their evolution through cosmic time, depend on the underlying cosmology of the Universe, showing that universes with an evolving and decaying dark sector leave a significant imprint on the void structure when compared to the standard Lambda Cold Dark Matter cosmology.

Speaker: Ms Eromanga Adermann (The University of Sydney)

EAdermann_CosPA2016.pptx

32 The Impact of Dark Sector Physics on Large-Scale Structure Topology

We compare the topological properties of the dark matter distribution in a number of cosmological models using hydrodynamical simulations and the cosmological genus statistic. Genus curves are computed from z=11 to z=0 for Lambda-CDM, Quintessence and Warm Dark Matter models, over a scale range of 1 to 20 h^-1 Mpc. The curves are analysed in terms of their Hermite spectra to describe the power contained in non-Gaussian deformations to the cosmological density field. We find that the Lambda-CDM and Lambda-WDM models produce nearly identical genus curves indicating no topological differences in structure formation. The Quintessence model, which differs solely in its expansion history, produces differences in the strength and redshift evolution of non-Gaussian modes associated with higher cluster abundances and lower void abundances. These effects are robust to cosmic variance and are characteristically different from those produced by tweaking the parameters of a Lambda-CDM model. Given the simplicity and similarity of the models, detecting these discrepancies represents a promising avenue for understanding the effect of non-standard cosmologies on large-scale structure.

Speaker: Mr Andrew Watts (The University of Sydney)

Dark matter

Convener: Giorgio Busoni

33 p-wave Annihilating Dark Matter from a Decaying Predecessor and the Galactic Centre Excess

Dark matter (DM) annihilations have been widely studied as a possible explanation of excess gamma rays from the galactic centre seen by the Fermi-LAT. However, most such models are in conflict with constraints from dwarf spheroidals. Motivated by this tension, in this talk I will show that p-wave annihilating dark matter can easily accommodate both sets of observations due to the lower DM velocity dispersion in dwarf galaxies. Explaining the DM relic abundance is then challenging. I will outline a scenario in which the usual thermal abundance is obtained through s-wave annihilations of a metastable particle that eventually decays into the p-wave annihilating DM of the present epoch. The couplings and lifetime of the decaying particle are constrained by big bang nucleosynthesis, the cosmic microwave background, and direct detection, but significant regions of parameter space are viable. A sufficiently large p-wave cross section can be found by annihilation into light mediators that also give rise to Sommerfeld enhancement. A prediction of the scenario is enhanced annihilations in galaxy clusters.

Speaker: Jonathan Cornell (McGill University)

Cornell-CosPA-p-wave.pdf

34 Semi-Annihilation and Dark Matter Indirect Detection

Semi-annihilation is a generic feature in dark matter theories with symmetries beyond Z2. We investigate some examples with either single- or multi- component dark sectors where semi-annihilation affects the phenomenology substantially. We also present a systematic tool to study models with semi-annihilation.

Speaker: Yi Cai (The University of Melbourne)

cospa.pdf

35 Dark Forces in the Sky: Signals from Z' and the Dark Higgs

We consider the indirect detection signals for models containing a fermionic DM candidate, a dark gauge boson, and a dark Higgs field. Compared with a model containing only a dark matter
candidate and vector mediator, the addition of the scalar provides a mass generation mechanism for the dark sector particles which, in some cases, is required in order to avoid unitarity violation at high energies. We demonstrate that the dark matter interaction types, and hence the annihilation processes relevant for relic density and indirect detection, are strongly dictated by the mass generation mechanism chosen for the dark sector particles, and the requirement of gauge invariance. We outline important phenomenology of such two-mediator models, which is missed in the usual single-mediator simplified model approach. In particular, the inclusion of the two mediators opens up a new, dominant, s-wave annihilation channel that does not arise when a single mediator is considered in isolation.

Speaker: Nicole Bell (University of Melbourne)

CosPA_Sydney_2016_Bell_revised.pdf

36 The Dark Matter Interpretation of the Gamma-Ray Excess at the Galactic Centre

An excess of gamma rays has been observed at the centre of the Galaxy. While dark matter
annihilation within the Milky Way’s halo has been shown to provide a good fit to the observed excess, evidence has recently arisen to suggest that the excess is emitted by a large number of point sources, such as millisecond pulsars. In this talk I present recent results that investigate gamma rays arising from annihilation within small-scale dark matter substructure, as a compromise between these two seemingly contradictory interpretations.

Speaker: Hamish Clark (University of Sydney)

HamishClark.pdf

Inflation and early universe cosmology

Convener: Sujeet Akula (Monash University)

37 Primordial massive gravitational waves in the squeezed vacuum state

We consider the Lorentz violating massive gravity for primordial gravitational waves and study the effects coming from the squeezed vacuum state on the subsequent B-mode polarization of the Cosmic Microwave Background. The resulting spectra oscillate on varying the mass of graviton and squeezing effect and are compared with the BICEP2/Keck Array at 150 GHz and Planck at 353 GHz collaboration data.

Speaker: Ms Malsawmtluangi Naulak (University of Hyderabad)

CosPA.pdf

38 Electroweak scale genesis by dynamical scale symmetry breaking and strong scale phase transition in the early universe

We consider a model
in which the electroweak scale
is non-perturbatively generated by
dynamical scale symmetry breaking
in a scalar QCD-like hidden sector.
We calculate
the energy spectrum of
cosmic gravitational wave background
which is produced by
the strong first-order scale phase transition
round O(TeV) in the early Universe.

Speaker: Jisuke Kubo (Kanazawa University)

cospa-kubo1.pdf

39 Gravitational Waves from Low Temperature Phase Transitions

Gravitational wave radiation can be formed in the early universe from bubbles originating from first-order phase transitions. Depending on the characteristics of the phase transition, the generated gravitational waves may be detected by future space-based gravitational wave detectors. Typically these transitions occur at time scales when the temperature of the universe was of order 50 GeV or earlier. In this talk, we look at much later phase transitions (around the 1 GeV range) and discuss the implications of these kinds of transitions. Specifically, we look at the possibility of detecting the resulting gravitational waves at current/future detectors.

Speaker: Adrian Manning (Sydney University)

COSPA.pdf

40 Probing physics behind the electroweak symmetry breaking at future gravitational wave interferometers and future collider experiments

Revealing dynamics of the electroweak phase transition is essential
for probing new physics at the early Universe
such as electroweak baryogenesis,
which requires strongly first order phase transition.
We compute the spectrum of gravitational waves from
first order phase transition in models with additional
isospin singlet scalars with and without classical scale invariance,
and in the extended Higgs model with a real singlet.
Predicted deviations in various Higgs boson couplings are also evaluated.
We show that these models can be tested by
the synergy of the measurements of the Higgs boson couplings at the LHC,
the measurement of the triple Higgs boson coupling at
future electron-positron colliders and the observation of
gravitational waves at future interferometers such as eLISA and DECIGO.
This talk is based on
Kakizaki, Kanemura, Matsui, PRD92 (2015) no.11,115007;
Hashino, Kakizaki, Kanemura, Matsui, PRD94 (2016) no.1, 015005;
Hashino, Kakizaki, Kanemura, Ko, Matsui, arXiv:1609.00297.

Speaker: Mitsuru Kakizaki (University of Toyama)

Kakizaki_JGRG161128.pdf

Particle astrophysics

Convener: Roland Crocker (Australian National University)

41 Prospects for detection of neutrinos in correlation with starburst galaxies

IceCube has detected many astrophysical neutrinos, but their ultimate origin is as-yet unknown. This talk will focus on starburst galaxies as a potential source of these neutrinos, and will discuss the prospects for finding correlations of these sources with the existing neutrino events.

Speaker: Alex Kyriacou (University of Adelaide)

42 Collapse of Axion Stars

Abstract

Axion stars, gravitationally bound states of low-energy axions, described by a field theory with potential energy $f^2 m^2(1-Cos (A/f))$ have
a maximum mass allowed by gravitational stability. Weakly bound states
obtaining this maximum mass have sufficiently large radii such that they are
dilute, and as a result, they are well described by a leading-order expansion
of the axion potential. Heavier states are susceptible to gravitational
collapse. Inclusion of higher-order interactions, present in the full
potential, can give qualitatively different results in the analysis of
collapsing heavy states, as compared to the leading-order expansion. In this
work, we find that collapsing axion stars are stabilized by repulsive
interactions present in the full potential, providing evidence that such
objects do not form black holes. These dense configurations, which are the
endpoints of collapse, have extremely high binding energy, and as a result,
quickly decay through number changing interactions.

Speaker: Rohana Wijewardhana (University of Cincinnati)

43 Soft X-ray excess from cosmic ALPs in magnetohydrodynamical cluster simulations

It has been proposed that the long-standing soft X-ray excess in galaxy clusters could be explained by conversion of a 200eV cosmic ALP background into photons in the cluster magnetic field. However, for an isotropic Gaussian model of the magnetic field in the Coma cluster, the excess is typically under-produced in the central region when compared to observations. In this talk I will explore whether this tension can be alleviated by considering anisotropic magnetic fields generated from magnetohydrodynamical models of cluster formation. I will present the results for three sample clusters and discuss how further simulations can constrain the allowed parameter space.

Speaker: Stephen Angus (IBS Center for Theoretical Physics of the Universe)

SAngus_CosPA2016.pdf

Event: Welcome Reception

Tuesday 29 November

Plenary

Convener: Nicole Bell (University of Melbourne)

HouskeepingCosPA_v2.pdf

HouskeepingCosPA_v2.pptx

44 Dark matter theory

Speaker: Paolo Gondolo (University of Utah)

Gondolo-CosPA2016.pdf

45 Dark matter direct detection

Speaker: Prof. Manfred Lindner (Max Planck Institut fuer Kernphysik, Heidelberg, Germany)

CosPA-Lindner.pdf

46 Darkly-Charged Dark Matter

Speaker: Lisa Randall (Harvard)

sydney2016dcdmdiskandpoints.pdf

sydney2016dcdmdiskandpoints.pptx

10:30 Coffee Break

Plenary

Convener: Gary Hill (University of Adelaide)

HouskeepingCosPA_v2.pdf

HouskeepingCosPA_v2.pptx

47 Galactic positron population

Speaker: Roland Crocker (Australian National University)

COSPA 2016 Crocker.pdf

48 AMS

Speaker: Mercedes Paniccia (Universite de Geneve (CH))

AMS_CosPA2016_MP.pdf

49 The Pierre Auger Observatory

Description of the Pierre Auger cosmic ray detector
Measurements of the energy spectrum, the arrival directions and the mass composition.
Searches for high energy photons, neutrons, neutrinos and high energy magnetic monopoles.

Speaker: Dr Jose Bellido (The University of Adelaide)

Jbellido_Auger.pdf

12:30 Lunch Break

Cosmic microwave background and Large Scale Structure

Convener: Dr David Parkinson (University of Queensland)

50 Relieving tensions related to the lensing of CMB temperature power spectra

The angular power spectra of the CMB temperature anisotropies reconstructed from Planck data seem to present ‘too much’ gravitational lensing distortion. This is quantified by the control parameter $A_L$ that should be compatible with unity for a standard cosmology. With the class Boltzmann solver and the profile likelihood method, we measure for this parameter a 2.6σ shift from 1 using the Planck public likelihoods. We show that, due to strong correlations with the reionization optical depth τ and the primordial perturbation amplitude $A_s$, a ∼ 2σ tension on τ also appears between the results obtained with the low ($\ell$ ≤ 30) and high (30 < $\ell$ < 2500) multipoles likelihoods. With Hillipop, another high-l likelihood built from Planck data, this difference is lowered to 1.3σ. In this case, the $A_L$ value is still discrepant with unity by 2.2σ, suggesting a non-trivial effect of the correlations between cosmological and nuisance parameters.
To better constrain the nuisance foregrounds parameters, we include the very-high-l measurements of the ACT and SPT experiments and obtain $A_L = 1.03 \pm 0.08$. The Hillipop+ACT+SPT likelihood estimate of the optical depth is τ = 0.052 ± 0.035 which is now fully compatible with the low-l likelihood determination. After showing the robustness of our results with various combinations, we investigate the reasons for this improvement, which results from a better determination of the whole set of foregrounds parameters. We finally provide estimates of the ΛCDM parameters with our combined CMB data likelihood.

Speaker: Dr Matthieu TRISTRAM (CNRS)

CosPA Alens and Hillipop.pdf

51 Planck constraints on scalar-tensor cosmology and the variation of the gravitational constant

Cosmological constraints on the scalar-tensor theory of gravity by analyzing the angular power spectrum data of the cosmic microwave background (CMB) obtained from the Planck 2015 results are presented. We consider the harmonic attractor model, in which the scalar field has a harmonic potential with curvature ($\beta$) in the Einstein frame and the theory relaxes toward the Einstein gravity with time.
Analyzing the TT, EE, TE and lensing CMB data from Planck by the Markov chain Monte Carlo method, we find that the present-day deviation from the Einstein gravity ${\alpha_0}^2$) is constrained as ${\alpha_0}^2<2.5\times10^{-4-4.5\beta}\ (95.45\% {\rm\ C.L.})$ and ${\alpha_0}^2<6.3\times10^{-4-4.5\beta}\ (99.99\%\ {\rm C.L.})$ for $0<\beta<0.4$. The time variation of the effective gravitational constant between the recombination and the present epochs is constrained as $G_{\rm rec}/G_0<1.0056\ (95.45\% {\rm\ C.L.})$ and $G_{\rm rec}/G_0<1.0115\ (99.99 \%{\rm\ C.L.})$. We also find that the constraints are little affected by extending to nonflat cosmological models because the diffusion damping effect revealed by Planck breaks the degeneracy of the projection effect.

Speaker: Junpei Ooba (Nagoya University)

CosPa2016_Junpei_Ooba.pdf

52 Modeling bispectrum in redshift space from perturbation theory

The observed galaxy clustering in redshift space, in nature, appears to be anisotropic due to the redshift-space distortion effects. This anisotropic clustering offers an interesting opportunity to probe gravity on cosmological scales. While the redshift-space distortion of galaxy clustering have been quantified and characterized by the two-point statistics, higher-order statistics such as bispectrum are also powerful measure for anisotropies, and combining the bispectrum with power spectrum, cosmological constraint will be further improved. In this talk, I will present a theoretical model of redshift-space bispectrum and quantify its validity by comparing N-body simulation. For an accurate theoretical template, we calculate bispectrum in redshift space based on perturbation theory up to next to leading order. In addition, we also consider relevant prescription for non-perturbative damping effect from the redshift-space distortion. Comparing with N-body simulations makes clear that our theoretical model works well in the quasi non-linear regime.

Speaker: Mr Ichihiko Hashimoto (Yukawa institute for theoretical physics)

Cospa_2016.pdf

53 Testing Inflationary Models with Galaxy Formation Simulations

Theories of cosmological inflation often predict that cosmic conditions will vary from place to place in the universe as a whole. In particular, the value of the cosmological constant can plausibly explained by a combination of environmental variation and it's effect on galaxy formation. In such models, it is crucial that we understand how quickly and efficiently the onset of accelerating expansion shuts down accretion of matter into dark matter haloes and galaxies. I will show simulations, based on the cosmological galaxy formationn code of the Eagle collaboration, that investigates this effect. More generally, I will show how an understanding of galaxy transformation can inform fundamental cosmology.

Speaker: Luke Barnes

54 Growth of perturbations in dark energy cosmologies

In the framework of the spherical collapse model, we study the non-linear growth of cosmic structures in the minimally and non-minimally coupled quintessence cosmologies. In non-minimally coupled quintessence models there is a non-minimally coupling between the scalar field and the Ricci scalar. We first investigate the background Hubble expansion in these models and then follow the models in perturbation levels. We see that the equation of state of dark energy in the case of non-minimally quintessence model can enter the phantom regime of expansion ($w_{de}<-1$) while in the minimally coupled quintessence models the equation of state is remaining in quintessence regimes $ w_{de} >-1$. On of the most important features of non-minimally coupled quintessence models is that the gravitational coupling $G$ is no longer constant and varies with cosmic time.
However, for a minimally quintessence models the gravitational coupling is constant, as defined in GR limit as $G_{N}$. Regarding to non-minimally quintessence models, the definition of gravitational coupling $G$ is basically different if we assume the perturbations of scalar fields or not. Notice that the perturbations of scalar fields can be assumed due to non-minimally coupling between scalar fields and Ricci scalar. We show that the scalar field perturbations have a significant impact on the evolution of gravitational coupling $G$. Since we have two different relations for effective gravitational coupling $G_{eff}$ according to the fact that the scalar field is clustered or not, we expect to see a different evolution for the growth of matter perturbations in the case of clustered non-minimally quintessence models compare to homogeneous quintessence models. We also compare the evolution of matter perturbations in both clustered and homogeneous non-minimally quintessence models with that of in minimally quintessence models in which the gravitational coupling $G$ is constant.

In linear regime of the growth of matter perturbations, we show that the quintessence term causes the decrements of the growth of structures at low redshifts ($z<1$). On the other hand at high redshifts ($z>1$) In particular, we will see that the growth factor of matter perturbations in non-minimally coupled quintessence models with positive (negative) coupling parameter is lower (higher) than that obtained in minimally coupled quintessence Universe. Moreover, the perturbations of scalar fields causes that the growth factor is decreasing compare to homogeneous cases.

In non-linear regime for the evolution of matter perturbations, we will show that the spherical collapse parameters $\delta_{c}$ and $\Delta_{vir}$ are strongly affected by perturbation of scalar field and moreover these quantities have different evolution for minimally, clustered non-minimally and homogeneous non-minimally quintessence models.
Notice that the linear overdensity parameter $\delta_{c}$ is a crucial parameter in Press Schechter formalism to calculate the abundance of virialized halos. Also the size of virialized halos can be obtained by using the virial overdensity $\Delta_{vir}$.
As an important result, we show that in all quintessence models, minimally or non-minimally coupled, the quantities $\delta_{c}$ and $\Delta_{vir}$ reach to $1.686$ and $178$, respectively. This result indicates that the early matter dominated Universe should be recovered in quintessence cosmological models, as expected.
We finally investigate the number count of massive halos for minimally and non-minimally coupled quintessence models. In prior case, the model gives an excess of
virialized halos with respect to the concordance $\Lambda$CDM model. While in the later case we show that the number of halos is higher (lower) that that of obtained in concordance $\Lambda$CDM scenario when the coupling parameter between scalar field and gravity is negative (positive).

Speaker: Mohammad Malekjani (Bu Ali Sina University, Depratment of Physics)

Sydney-Presentation.pdf

Dark matter

Convener: Yi Cai

55 Global fits of the scalar singlet model using GAMBIT

I will present the latest results for global fits to the Higgs portal scalar singlet extended standard model using complementary probes of dark matter. In doing so I will introduce the new global and modular beyond the standard model inference tool (GAMBIT) which is used to achieve these results in a statistically consistent and modular way. I will also demonstrate the flexibility and consistency between the choice of statistical fitting algorithms available with this tool.

Speaker: James McKay (Imperial College London)

CosPA_2016.pdf

56 Effective vector and fermion Higgs portal: A global study with GAMBIT

We perform a global study of the effective vector and fermion Higgs portal models of dark matter (DM) using the Global And Modular Beyond-the-Standard-Model Inference Tool (GAMBIT) package. Within the effective field theory (EFT) approach, DM communicates with the Standard Model (SM) Higgs boson via an operator of the form $\mathcal{O}_{\mathrm{DM}} H^\dagger H$. For the fermion models, we take an admixture of the scalar $\overline{\psi}\psi$ and pseudoscalar $\overline{\psi}i\gamma_5 \psi$ interaction terms. Using a combined likelihood function which includes a contribution from the Planck measured relic density, LHC limits on the Higgs invisible width as well as the indirect and direct detection experiments, current limits are placed on each of the model parameter space. Uncertainties associated with a series of nuisance parameters such as the DM halo distribution, SM masses/couplings, and the nuclear matrix elements relevant for the calculation of direct search yields are all accounted by associating them with a corresponding likelihood term in the combined likelihood. Depending on the method chosen for statistical inference (Bayesian and/or frequentist), these nuisance parameters are integrated and/or marginalised out to yield a first set of preliminary results. From these results, we find that current DM searches significantly exclude much of the model parameter space. Further exclusion will be possible when the next generation of indirect and direct DM search experiments become operational.

Speaker: Mr Ankit Beniwal (University of Adelaide (AU))

AB_CosPA_2016.pdf

57 Evaporation on Gev-ish DM in the Sun

We analyse the effect of evaporation on Dark Matter in the Sun, considering velocity and momentum suppressed cross sections. We check which best-fit points of 1605.06502 are affected by evaporation.

Speaker: Giorgio Busoni

COSPA_2016.pdf

58 Plasma Dark matter direct detection

Dark matter might exist in the Milky Way as a dark plasma. Such dark matter arises
in models where dark matter originates from a hidden sector featuring a massless ‘dark photon’, including mirror dark matter. In such a scenario, the implications for direct detection experiments are very different from the more commonly studied case of WIMP dark matter. In particular electron recoils can be the dominant process leading to keV energy depositions in detectors. In addition, large annual modulation and sidereal daily modulation signals become characteristic features of such dark matter. The possibility that plasma dark matter might be the origin of the DAMA annual modulation signal is also discussed, along with the expectations of what might be expected in the near future from other experiments. This work is based on recent work including: arXiv:1512.06471 (in collaboration with J. Clarke),
arXiv:1412.0762 (in collaboration with S. Vagnozzi), arXiv:1407.4213.

Speaker: Dr Robert Foot (COEPP)

Plasma dark matter direct detection.pdf

59 Halo-independent tests of dark matter direct detection signals

I will discuss halo-independent tests of direct detection signals that we have derived in recent works. In the first part [1502.03342 (elastic scattering) and 1512.03317 (inelastic)], I will discuss a halo-independent lower bound on the DM capture rate in the Sun from a direct detection signal, with which one can set limits on the branching ratios into different channels from the absence of a high-energy neutrino flux in neutrino telescopes. In the second part [based on 1505.05710], I will discuss a lower bound one can set on the product of the DM-nucleon cross section and the energy density from a direct detection signal that is independent of the velocity distribution, and how this bound can be combined with limits from local density measurements, the LHC and the relic abundance in order to constraint DM models.

Speaker: Dr Juan Herrero Garcia (University of Adelaide - CoEPP)

halo_COSPA.pdf

Inflation and early universe cosmology

Convener: Kazunori Kohri (KEK)

60 Inflation from Supergravity with Gauged R-symmetry in de Sitter Vacuum

We present the results based on arXiv:1608.02121

Speaker: Dr Rob Knoops (Chulalongkorn University, Bangkok)

COSPA2016_RKnoops.pdf

61 Multi-phase inflation and endlessly flat scalar potentials

In my talk I will present an idea of a scalar theory with a general potential $V(f(\varphi))$, where $f(\varphi) = \xi\sum_{k=1}^n \lambda_k \varphi^k$. I will show how to obtain generally flat inflationary potentials from such a model and prove that the Starobinsky inflation is one of the examples of $V(f)$ with a stationary point of an infinite order. I will generalise this model into a scalar-tensor theory, which leads to multi-phase inflation, with two inflationary plateaus. I will also show the equivalence of this picture to $\alpha$-attractors.

Speaker: Dr Michal Artymowski (Jagiellonian University)

Sydney_COSPA_2016_Artymowski_talk.pdf

62 Ahead of the hunt: leading small field inflationary potential models.

I will first present in broad strokes the numerical package employed, and discuss regression tests to fully analytical cosmological models. I will then go on to present the early work done on the subject of small-scale 5th degree polynomial models, which were first suggested by Ben-Dayan et al. in 2010. These models successfully yield an inflationary scenario with a non-negligible $n_{run}$, and $r$ as high as $0.001$. This work demonstrates the need for high accuracy numerical tools in the field of cosmological model building. I will continue to present the ongoing work (about to publish late August/early September) which studies models with $r$ as high as $0.05$. These models present in addition to significant running, significant running of running. I will present the analysis of CMB data which takes into account $n_{run,run}$, along the same outline as the one done by Cabass et al. . I will then demonstrate using this data to recover a most probable 6th degree polynomial inflationary potential.

Speaker: Mr Ira Wolfson (Ben Gurion University of the Negev)

CosPa_nov_2016_IraWolfson_v1.pdf

CosPa_nov_2016_IraWolfson_v1.pptx

Scale dependence of the CMB power spectrum in small field models of inflation with a high tensor to scalar ratio

63 Violent preheating in inflation with nonminimal coupling

Particle production at the preheating era in inflation models with nonminimal coupling $ξ|φ|^2R$ and quartic potential $λ|φ|^4/4$ is discussed. We point out that the preheating proceeds much more violently than previously thought: if the inflaton is a complex scalar, the phase degree of freedom (global case) or the longitudinal gauge boson (gauged case) is violently produced at the first stage of preheating by "spike" in the time dependence of the inflaton field. Produced particles typically have very high momenta $k \sim λ M_P$, and the production is so strong that almost all the energy of the inflaton can be carried away within one oscillation for $ξ^2λ > 1$. This may change the conventional understandings of the (p)reheating after inflation with nonminimal coupling to gravity, such as Higgs inflation. We also discuss the possibility of unitarity violation.

Speaker: Dr Ryusuke Jinno (Institute for Basic Science (IBS))

CosPA_Jinno.key

CosPA_Jinno.pdf

Particle physics

Convener: Dr Matthew Dolan (University of Melbourne)

64 Collider searches for Higgs portal DM models

This talk will be based on these papers:

(1) Beyond the Dark matter effective field theory and a simplified model approach at colliders
Seungwon Baek, P. Ko (Korea Inst. Advanced Study, Seoul), Myeonghun Park (APCTP, Pohang & POSTECH, Pohang & Tokyo U., IPMU), Wan-Il Park (Valencia U. & Valencia U., IFIC), Chaehyun Yu (Taiwan, Inst. Phys.). Jun 22, 2015. 6 pp.
Published in Phys.Lett. B756 (2016) 289-294
APCTP-PRE2015-014, IPMU15-0084, FTUV-15-06-25, IFIC-15-38, KIAS --P15029
DOI: 10.1016/j.physletb.2016.03.026
e-Print: arXiv:1506.06556 [hep-ph]

(2) Search for Higgs portal DM at the ILC
P. Ko, Hiroshi Yokoya (Korea Inst. Advanced Study, Seoul). Mar 15, 2016. 24 pp.
Published in JHEP 1608 (2016) 109
DOI: 10.1007/JHEP08(2016)109
e-Print: arXiv:1603.04737 [hep-ph]

Speaker: pyungwon ko (Korea Inst. for Advanced Study (KIAS))

BeyondEFT_CosPA2016.pdf

65 The muon g-2 and dark matter in the MSSM at 100 TeV

We study the muon g-2 and neutralino dark matter as explained by the MSSM where the squarks and 3rd generation sleptons are decoupled. Particularly, we focus on constraints from current and future dark matter experiments such as PandaX-II and LUX-2016 as well as current bounds from collider searches. Using the constraints on the MSSM from the muon g-2 and DM searches, we study constraints from multilepton + MET searches at 8 TeV LHC, and the prospects for searches at 100 TeV proton-proton collision energies.

Speaker: Matthew Talia (University of Sydney)

susy-g-2.pdf

66 Mono-top/bottom signature in natural SUSY at LHC

The determination of the electroweak properties of the stop will be an essential task for the LHC. We investigate the observability of single stop production through Mono-top/bottom channel in natural supersymmetry at the LHC.

Speaker: Dr Lei Wu (The University of Sydney)

main.pdf

67 CP violating Top-Higgs couplings in Light of LHC Run-2

We utilize the LHC Run-2 Higgs data to constrain the CP-violating top-Higgs coupling. Within the allowed parameter space, we study the impact of the CP-violating top-Higgs coupling in the Higgs production processes $pp \to t\bar{t}h, thj, hh$ at 14 TeV LHC, and $e^+e^- \to Zh, h\gamma$ at 240 GeV CEPC.

Speaker: Dr Ning Liu (The University of Sydney)

68 Implication of ALEPH 30 GeV dimuon resonance at the LHC

Recent reanlysis of ALEPH data seems to indicate dimuon excess around 30 GeV dimuon in Z -> b bar{b} mu^+ mu^- with a branching fraction around 1.1 X 10^{-5}. We discuss a few simplified models for the dimuon excess. In the first class of models, we assume a new resonance couples to both b bar{b} and mu^+ mu^-. Within the allowed parameter space for the ALEPH data, this type of models is excluded because of too large Drell-Yan production of&nbs p;dimuon from the b bar{b} collision at the LHC. In the second model, we assume that the 30 GeV excess is a new gauge boson Z' that couples to the SM b and a new vectorlike singlet B quark heavier than Z and not to b bar{b}. Then one can account for the ALEPH data without conflict with the DY constraint. We discuss implication of the model at the LHC.

Speaker: Chaehyun Yu (Korea University)

ALEPHexcess,chyu.pdf

15:40 Coffee Break

Cosmic microwave background and Large Scale Structure

Convener: David Wiltshire (University of Canterbury)

69 Magnetic fields at cosmological recombination

In the context of the standard cosmological perturbation theory, non-linear couplings of first-order scalar perturbations create second-order vector perturbations, which generate magnetic fields through the Harrison mechanism.
We find that the magnetic fields from the purely second-order vector perturbations partially cancel out the magnetic fields from one of the product-terms of the first-order scalar modes. Therefore, the amplitude of the magnetic fields on small scales, $k\geq 10 h{\rm Mpc}^{−1}$, is smaller than the previous estimates. The amplitude of the generated magnetic fields at cosmological recombination is about $B_{\rm rec}=5.0\times 10^{−24} {\rm Gauss}$ on $k=5.0\times 10^{−1} h{\rm Mpc}^{−1}$. Finally, we discuss the reason of the discrepancies that exist in estimates of the amplitude of magnetic fields among other authors.

Speaker: Shohei Saga (Nagoya University)

CosPA_saga.pdf

70 Test of the Einstein equivalence principle with CMB spectral distortions

The Einstein Equivalence Principle (EEP) is one of the fundamental principles in General Relativity. One of the consequences of the EEP in the cosmological context is the energy independency of the cosmological redshift effect. Here we propose a new test of the energy independency of the redshift effect by the measurement of the spectral distortions of the Cosmic Microwave Background (CMB). In GR, the energy independency of the redshift effect is ensured by the Friedmann-Robertson-Walker metric which does not depend on energy. We show that the CMB spectral distortions arise when the FRW metric has the energy dependence. Our result is consistent with no energy-dependence of the redshift effect, at least, with a precision of $10^{−6}$ on the CMB energy scales.

Speaker: Dr Hiroyuki Tashiro (Nagoya University)

Tashiro_cospa2016.pdf

71 Differential expansion and its observational impact in cosmology

In general relativity inhomogeneities generically produce differential cosmic expansion which is not equivalent to a homogeneous isotropic cosmology plus local boosts, as assumed in the current standard model. We present the first ray tracing simulations of local structure that exhibit this, using exact solutions of Einstein's equations constrained by both actual large galaxy surveys (the COMPOSITE sample) and the Cosmic Microwave Background. We use exact Szekeres solutions on small scales which asymptote to a Planck-satellite normalized FLRW model on scales >100/h Mpc. We discuss the impact on issues including the local and global values of the Hubble constant, and large angle CMB anomalies.

Reference: K. Bolejko, M.A. Nazer and D.L. Wiltshire, JCAP 06(2016)035

Speaker: Krzysztof Bolejko (University of Sydney)

72 Shear and rotation in massive galaxy clusters

Massive galaxy clusters, being at the high mass end of the mass function are becoming a common tool in cosmology. Their
abundance is a strong indicator of non-linear structure formation and it depends on the value of important cosmological
parameters, such as the matter density parameter $\Omega_{\rm m}$, the mater power spectrum normalization $\sigma_8$
and the dark energy equation of state $w_{\rm de}$. A precise determination of the mass function is a current goal of
both theoretical and observational studies, due to the wealth of implications related to it.

From a theoretical point of view, the mass function is related to the function $\delta_{\rm c}$, that, in the framework
of the spherical collapse model, represents the density above which structures can form. In the standard approach,
perturbations are assumed to be spherical and non rotating, but in an era of precision cosmology it is necessary to
relax this assumption. Shear and rotation can be added naturally into this formalism as shown recently by
(Del Popolo et al.
2013; Pace et al. 2014) and their combination is parametrized via the parameter $\alpha$. This
extension of the simple spherically symmetric model makes such that $\delta_{\rm c}$ is now a function of both mass and
redshift, contrary to the standard case where it only depends on time. This implies that the mass function and hence
the total number of objects that can be observed will strongly depend on the evolution with mass of the parameter
$\alpha$. Since theory, so far, does not constrain it, in this work we choose a particularly simple form:
$\alpha=-\beta\log_{10}\frac{M}{M_s}$, where $\beta$ is the slope of the logarithmic relation and
$M_s=8\times 10^{15}~h^{-1}~M_{\odot}$ is a normalization mass. When $M=M_s$, deviation from sphericity are null and we
recover the standard case.

The combined effect of shear and rotation, due to the dominance of the latter, implies a decreased number of objects
with respect to the spherically symmetric case since structure formation is slowed down.

Using data on massive clusters by (Campanelli et al. 2012) we constrain the value of the slope $\beta$ and we infer its
consequences on the number of massive objects. In our analysis we find $\Omega_{\rm m}=0.284\pm0.0064$,
$h=0.678\pm0.017$ and $\beta=0.0019^{+0.0008}_{-0.0015}$ at $1-\sigma$ level, when keeping $\sigma_8=0.818$ fixed and
restricting our analysis to a flat $\Lambda$CDM model.

Speaker: Ahmad Mehrabi (Bu-Ali Sina university)

present.pdf

73 Cosmological effects of Late Forming Dark Matter

The standard $\Lambda$CDM model with WIMP dark matter describes the large scale features of the universe
quite well with some potential unsolved astrophysical problems in the small scale. In this study, we propose
a different type of CDM which forms much after the BBN and before the epoch of matter radiation
equality. We consider two such dark matter models. The Late Forming Dark Matter (LFDM)
and the Ultra-Light Axion Dark Matter(ULADM). Both of these models show sharp suppression in
small scale power followed by oscillations in the matter power spectra.We have compared our results
with various power spectrum data available and found the formation redshift $z_f$ to be greater
than $10^5$, at 99% CL. To check the effects of these features in the small scale power on the history
of the universe, we study two cosmological observables in the framework of these models: the
redshifted 21-cm signal from the epoch of reionization and the evolution of the collapsed fraction
of HI in the redshift range $2 < z < 5$. We have studied these models assuming a fiducial model
of reionization where a neutral hydrogen fraction $x_{\rm HI}$ = 0.5 must be achieved by z = 8. The
reionization process allows us to put approximate bounds on the redshift of dark matter formation
$z_f > 4 \times 10^5$
and the ULA mass $m_a > 2.6 \times 10^{−23}$ eV. The comparison of the collapsed mass
fraction inferred from damped Lyman-$\alpha$ observations to the theoretical predictions of our models
lead to the weaker bounds: $z_f > 2 \times 10^5$
and $m_a > 10^{−23}$ eV. All of these results are consistent
with our previous results.

Speaker: Mr Abir Sarkar (Raman Research Institute)

Abir_talk.pdf

Abir_talk.pptx

Dark matter

Convener: pyungwon ko (Korea Inst. for Advanced Study (KIAS))

74 New effects of dark matter which are linear in the interaction strength

Low-mass boson dark matter particles produced after Big Bang form classical field and/or topological defects. In contrast to traditional dark matter searches, effects produced by interaction of an ordinary matter with this field and defects may be first power in the underlying interaction strength rather than the second power or higher (which appears in a traditional search for the dark matter) [1-12]. This may give a huge advantage since the dark matter interaction constant is extremely small.
Interaction between the density of the dark matter particles and ordinary matter produces both ‘slow’ cosmological evolution and oscillating variations of the fundamental constants including the fine structure constant alpha and particle masses [4]. Recent atomic dysprosium spectroscopy measurements and the primordial helium abundance data allowed us to improve on existing constraints on the quadratic interactions of the scalar dark matter with the photon, electron and light quarks by up to 15 orders of magnitude. Limits on the linear and
quadratic interactions of the dark matter with W and Z bosons have been obtained for the first time.
In addition to traditional methods to search for the variation of the fundamental constants (atomic clocks, quasar spectra, Big Bang Nucleosynthesis, etc) we discuss variations in phase shifts produced in laser/maser interferometers (such as giant LIGO, Virgo, GEO600 and TAMA300, and the table-top silicon cavity and sapphire interferometers) [5,6], changes in pulsar rotational frequencies (which may have been observed already
in pulsar glitches), non-gravitational lensing of cosmic radiation and the time-delay of pulsar signals [4].
Other effects of dark matter and dark energy include apparent violation of the fundamental symmetries: oscillating or transient atomic electric dipole moments, precession of electron and nuclear spins about the direction of Earth’s
motion through an axion condensate (the axion wind effect), and axion-mediated spin-gravity couplings [8-10], violation of Lorentz symmetry and Einstein equivalence principle [11,12].
Finally, we explore a possibility to explain the DAMA collaboration claim of dark matter detection by the dark matter scattering on electrons. We have shown that the electron relativistic effects increase the ionization differential cross section up to 3 orders of magnitude [13,14].
[1] M. Pospelov, S. Pustelny, M. P. Ledbetter, D. F. Jackson Kimball, W. Gawlik, and D. Budker. Phys. Rev. Lett. 110, 021803 (2013).
[2] A. Derevianko and M. Pospelov. Nature Physics 10, 933 (2014).
[3] P.W. Graham, S. Rajendran. Phys. Rev. D84,055013 (2011); D88,035023 (2013).
[4] Can dark matter induce cosmological evolution of the fundamental constants of Nature? Y. V. Stadnik and
V. V. Flambaum. Phys. Rev. Lett. 115, 201301 (2015).
[5] Searching for Dark Matter and Variation of Fundamental Constants with Laser and Maser Interferometry.
Y. V. Stadnik and V. V. Flambaum. Phys. Rev. Lett. 114, 161301 (2015).
[6] Enhanced effects of variation of the fundamental constants in laser interferometers and application to dark
matter detection, Y. V. Stadnik, V. V. Flambaum, arXiv:1511.00447
[7] Searching for Topological Defect Dark Matter via Nongravitational Signatures. Y. V. Stadnik and
V. V. Flambaum. Phys. Rev. Lett. 113, 151301 (2014).
[8] Axion-induced effects in atoms, molecules and nuclei: Parity nonconservation, anapole moments, electric
dipole moments, and spin-gravity and spin-axion momentum couplings. Y. V. Stadnik and V. V. Flambaum.
Phys. Rev. D 89, 043522 (2014).
[9] Limiting P-odd Interactions of Cosmic Fields with Electrons, Protons and Neutrons. B. M. Roberts,
Y. V. Stadnik, V. A. Dzuba, V. V. Flambaum, N. Leefer and D. Budker. Phys. Rev. Lett. 113, 081601 (2014).
[10] Parity-violating interactions of cosmic fields with atoms, molecules and nuclei: Concepts and calculations
for laboratory searches and extracting limits. B. M. Roberts, Y. V. Stadnik, V. A. Dzuba, V. V. Flambaum,
N. Leefer and D. Budker. Phys. Rev. D 90, 096005 (2014).
[11] V.A. Dzuba, V.V. Flambaum, M. Safronova, S.G. Porsev, T. Pruttivarasin, M.A. Hohensee, H. Haffner.
Nature Physics (2016), DOI:10.1038/nphys3610.
[12] Enhanced violation of the Lorentz invariance and Einstein equivalence in atoms and nuclei, V.V. Flambaum.
arxiv: 1603.05753
[13] Ionization of atoms by slow heavy particles, including dark matter. B. M. Roberts, V. V. Flambaum, and
G. F. Gribakin, Phys. Rev. Lett. 116, 023201 (2016).
[14] Dark matter scattering on electrons: Accurate calculations of atomic excitations and implications for DAMA signal. B.M. Roberts, V.A. Dzuba, V.V. Flambaum, M. Pospelov, Y.V. Stadnik, Phys.Rev.D93,115037 (2016).

Speaker: Prof. Victor Flambaum (University of New South Wales)

FlambaumCosPA2016.pdf

FlambaumCosPA2016.ppt

75 Searching for dark matter and exotic bosons with atoms, molecules and ultracold neutrons

We propose new schemes for the direct detection of dark matter and exotic bosons in experiments involving atoms, molecules and ultracold neutrons. Dark matter, which consists of low-mass bosons (such as axions, pseudoscalars or scalars), can readily form an oscillating classical field that survives to reside in the observed galactic dark matter haloes if these particles have sufficiently low mass and are sufficiently feebly interacting.

An oscillating classical dark matter (axion or pseudoscalar) field can give rise to a number of oscillatory spin-dependent effects in the laboratory. These effects include the precession of polarised spins about Earth's direction of motion though galactic dark matter [1-3], and induced oscillating electric dipole moments of atoms, molecules and nucleons [3-5]. We are currently working with the nEDM collaboration to search for these oscillatory spin-dependent effects using a dual neutron/$^{199}$Hg co-magnetometer [6].

An oscillating classical dark matter (scalar) field can produce both `slow' cosmological evolution and oscillating variations in the fundamental constants [7], which can be sought for in astrophysical phenomena and in the laboratory. Using data pertaining to Big Bang nucleosynthesis, as well as atomic spectroscopy measurements in the laboratory [8,9], we have derived limits on interactions of dark matter with Standard Model particles that improve on existing constraints by up to 15 orders of magnitude [7]. In the laboratory, we can also use laser and maser interferometry as another high-precision platform to search for dark matter via the effects of variation of fundamental constants [10].

Exotic scalar fields may also be sourced by massive bodies. Using atomic spectroscopy measurements in the laboratory, we have derived limits on the interactions of such scalar particles with Standard Model particles, including constraints on combinations of interaction parameters which cannot otherwise be probed with traditional anomalous-force measurements [11]. We suggest further measurements to improve on the current level of sensitivity [11].

References:
[1] V. V. Flambaum, talk presented at the 9th Patras Workshop on Axions, WIMPs and WISPs, Schloss Waldthausen, Mainz, Germany, 24th June 2013, http://axion-wimp2013.desy.de/e201031
[2] P. W. Graham and S. Rajendran, PRD 88, 035023 (2013).
[3] Y. V. Stadnik and V. V. Flambaum, PRD 89, 043522 (2014).
[4] P. W. Graham and S. Rajendran, PRD 84, 055013 (2011).
[5] B. M. Roberts, Y. V. Stadnik, V. A. Dzuba, V. V. Flambaum, N. Leefer and D. Budker, PRL 113, 081601 (2014); PRD 90, 096005 (2014).
[6] N. J. Ayres, P. G. Harris, K. Kirch and M. Rawlik (on behalf of the nEDM collaboration), and M. Fairbairn, V. V. Flambaum, D. J. E. Marsh and Y. V. Stadnik, ongoing work.
[7] Y. V. Stadnik and V. V. Flambaum, PRL 115, 201301 (2015); PRA 94, 022111 (2016).
[8] K. Van Tilburg, N. Leefer, L. Bougas and D. Budker, PRL 115, 011802 (2015).
[9] A. Hees, J. Guena, M. Abgrall, S. Bize and P. Wolf, PRL 117, 061301 (2016).
[10] Y. V. Stadnik and V. V. Flambaum, PRL 114, 161301 (2015); PRA 93, 063630 (2016).
[11] N. Leefer, A. Gerhardus, D. Budker, V. V. Flambaum and Y. V. Stadnik, arXiv:1607.04956.

Speaker: Yevgeny Stadnik (University of New South Wales)

Stadnik_CosPA_FINAL.pdf

76 Quantum and Classical Behaviour of Axion Dark Matter

It is understood that in free bosonic theories, the classical field theory accurately describes the full quantum theory when the occupancy numbers of systems are very large. However, the situation is less understood in interacting theories, especially on time scales longer than the dynamical relaxation time. Recently there have been claims that the quantum theory of dark matter axions deviates spectacularly from the classical theory on this time scale, even if the occupancy numbers are extremely large. The evidence for these claims comes from noticing a spectacular difference in the time evolution of expectation values of quantum operators compared to the classical micro-state evolution. In this talk I critically examine these claims. I show that in fact the classical theory can describe the quantum behaviour in the high occupancy regime, even when interactions are large. The connection is that the expectation values of quantum operators in a single quantum micro-state are approximated by a corresponding classical ensemble average over many classical micro-states. Furthermore, by the ergodic theorem, a classical ensemble average of local fields with statistical translation invariance is the spatial average of a single micro-state. So the correlation functions of the quantum and classical field theories of a single micro-state approximately agree at high occupancy, even in interacting systems. I discuss applications of our results to axion dark matter. I use the classical field theory to show that axions form Bose condensed stars within the galaxy.

Speaker: Prof. Mark Hertzberg (Tufts University)

HertzbergAxionsAIPCosPA.pdf

77 A dark matter model with Dirac neutrino masses

Tiny neutrino masses can be obtained if right-handed neutrino masses charged under a global U(1) symmetry and a second Higgs doublet which is also charged under the U(1) obtains tiny vacuum expectation value.
Due to the symmetry Majorana mass terms of the right-handed neutrinos are not allowed and the usual seesaw mechanism does not work.
We can also introduce dark matter candidates whose stability is also guaranteed by the same U(1).
I'll talk about the phenomenology of this model.

Speaker: Seungwon Baek

CosPA_Baek.pdf

Inflation and early universe cosmology

Convener: Archil Kobakhidze (The University of Sydney)

78 Blue tensor spectra with slightly parity-violated from axion-gauge couplings

The inflationary universe predicts vacuum fluctuations of space-time, called primordial gravitational waves, whose spectra have slightly red-tilted and parity-symmetric features. This is an ordinary picture. Intriguingly, however, it is known that the axion-gauge coupling, motivated by string theory, could occur the particle production of gauge fields during inflation and provide the parity-violated blue tensor spectrum testable in future gravitational wave experiments, while no such a parity-violated primordial signal has been detected through recent observations. It seems that there would be no parity-violated phenomena in the early universe. In this talk, however, we suggests the new mechanism of providing blue tensor spectra sourced by gauge fields coupled to axions, surprisingly whose amplitudes are almost parity-conserved but slightly parity-violated! We expect that the blue tensor spectra with little chirality becomes the new window to the axion phenomenology in the early universe.

Speaker: Ippei Obata (Kyoto University)

CosPA_2016.pdf

CosPA_2016.pptx

79 Naturalness of the relaxion mechanism

The relaxion mechanism is a novel solution to the hierarchy problem that utilizes the dynamics of an axion-like field. I discuss results from the first statistical analysis of the relaxion mechanism (arXiv:1602.03889), in which we quantified the relative plausibility of a QCD and a non-QCD relaxion model versus the Standard Model with Bayesian statistics, which includes an automatic penalty for fine-tuning. We included experimental constraints upon the weak-scale, $\theta_\text{QCD and inflationary observables measured by Planck/BICEP. Whilst we confirmed that relaxion models could solve the hierarchy problem, we found that their unconventional cosmology demolishes their plausibility.

Speaker: Dr Andrew Fowlie (Monash University)

relaxion.pdf

80 Gravitational waves at aLIGO and vacuum stability with a scalar singlet extension of the Standard Model

A new gauge singlet scalar field can undergo a strongly
first-order phase transition leading to gravitational waves observable
at aLIGO and stabilizes the electroweak vacuum at the same time. This
is because the sensitivity of aLIGO to cosmological phase transitions
at 10^7-10^8 GeV coincides with the requirement that the singlet scale
is close to the Standard Model instability scale. Extending the SM
with a singlet, we calculate the nucleation temperature and order
parameter of the PT during which the singlet acquires a vacuum
expectation value in terms of Lagrangian parameters. Relating the
thermodynamic quantities to the peak frequency and amplitude of the
gravitational waves created during the phase transition, we present
three benchmark points for which not only are gravitational waves
observable at aLIGO but the electroweak vacuum is stable and the zero
temperature phenomenology is acceptable. This scenario offers an
intriguing possibility for aLIGO to detect traces of fundamental
physics motivated by vacuum stability at an energy scale that is well
above the reach of any other experiments.

Speaker: Csaba Balazs (Monash University)

GWs SM+SS.pdf

81 Gravitational Wave Instabilities in the Cosmic Neutrino Background

We investigate the propagation of gravitational waves through the cosmic neutrino background, assuming it carries a non-zero lepton asymmetry. In this background, the graviton dispersion relation is found to exhibit birefringent behaviour leading to an enhancement/suppression of the gravitational wave amplitudes depending on the polarisation, where the magnitude of this effect is related to the size of the lepton asymmetry. The heralding of the new era of gravitational wave astronomy may allow the investigation of this behaviour and provide an indirect way to learn about the properties of the cosmic neutrino background and the neutrino sector.

Speaker: Neil Barrie (The University of Sydney)

NDB_Cospa.pdf

Particle astrophysics

Convener: Mercedes Paniccia (Universite de Geneve (CH))

82 Precision Measurement of the Positron, Electron and Antiproton Fluxes in Primary Cosmic Ray with the Alpha Magnetic Spectrometer on the International Space Station

The Alpha Magnetic Spectrometer, AMS, is a general purpose high energy particle physics detector. It was installed on the International Space Station, ISS, on 19 May 2011 to conduct a unique long duration mission of fundamental physics research in space.

In this contribution, precision measurements by AMS of the primary cosmic ray positron flux, electron flux and antiproton flux are presented. These measurements increase the precision of the previous observations and significantly extend their energy range. Based on these measurement, new observations of the properties of the flux ratios of charged elementary particles in cosmic rays are presented. Together, they provide important information on the origins of cosmic-ray charged elementary particles.

Speaker: Zhili Weng (Massachusetts Inst. of Technology (US))

CosPA2016_AMSPositronElectronAntiproton_ZWeng_20161129.pdf

83 Precision Measurement of Nuclei Fluxes and their Ratios in Primary Cosmic Rays with the Alpha Magnetic Spectrometer on the International Space Station

The exact behavior of the nuclei fluxes with rigidity and how they relate to each other is important for understanding the production, acceleration and propagation mechanisms of charged cosmic rays. Precise measurements with the Alpha Magnetic Spectrometer on the International Space Station of the light nuclei fluxes and their ratios in primary cosmic rays with rigidities from GV to TV range will be discussed.

Speaker: Valerio Formato (Universita e INFN, Perugia (IT))

COSPA_2016_Nuclei_AMS_Formato.pdf

84 Astrophysical signatures from Galactic positronium, true muonium and true tauonium

The annihilation of electrons and positrons in the Galactic centre has been observed since the 1970s, yet the origin of the positrons is still unknown. Models of high energy astrophysical sources, such as supernovae and low mass X-ray binaries, must be able to explain the very high bulge-to-disc ratio of the annihilation emission, either via the distribution of the sources or via the propagation of the positrons through the ISM. Alternative possibilities include dark matter decay, or the supermassive black hole, both of which would have a naturally high bulge-to-disc ratio.

The chief difficulty in reconciling models with the observations is the intrinsically poor angular resolution of gamma ray observations, which cannot resolve point sources. However, 95% of the positrons annihilate via the formation of positronium, a short lived atom consisting of an electron and a positron. This gives rise to the possibility of observing recombination lines of positronium emitted before the atom annihilates. These emission lines would be in the UV and the NIR, giving an increase in angular resolution of a factor of $10^{4}$ compared to gamma ray observations, and allowing the discrimination between point sources and truly diffuse emission.

Analogously to the formation of positronium, it is possible to form atoms of muons and anti-muons and tauons and anti-tauons. Since muons and tauons are intrinsically unstable,
the formation of such leptonium atoms will be localised to their places of origin. Thus observations of true muonium or true tauonium can provide another way to distinguish between truly diffuse sources such as dark matter decay, and point sources such as supernovae, etc.

We will review the possibility of detecting positronium recombination lines, and the observational signatures of leptonium from astrophysical sources, and discuss the possibilities of resolving the problem of the origin of the Galactic positrons.

Speaker: Simon Ellis (AAO)

leptonium2.pdf

85 The Statistics of Unresolved Point-Source Populations

Conventional gamma-ray point-source searches involve looking for sources that are individually detectable with a predetermined statistical significance. A shortcoming of this approach is that a population of sources that are each below this statistical threshold cannot be found. Nevertheless such a population will modify the statistics of the dataset away from a Poisson distribution and can be uncovered using the recently introduced Non-Poissonian Template Fit (NPTF) method. In this talk I will outline a code package, which will be publicly released shortly, that can be used to apply the NPTF to astrophysical datasets. As I will review, this code has already been used to uncover a number of features of the gamma-ray sky, such as the likely point-source origin of the galactic centre excess, and is currently being applied to other datasets, including Icecube neutrinos.

Speaker: Nicholas Rodd (Massachusetts Institute of Technology)

NPTFit.pdf

86 Gas Towards Gamma-Ray-Emitting Supernova Remnants

Gamma-ray astronomy may offer answers to a long-standing question of high energy astrophysics: Where do cosmic rays come from? The gamma-ray emission seen from some supernova remnants is now known to be from distant populations of cosmic-rays (probably accelerated locally) interacting with gas, but there is still much work to be done in accounting for the Galactic cosmic-ray flux. The Mopra radio telescope is ideal for probing the interstellar environments of gamma-ray sources through large-scale molecular line surveys. The Mopra Galactic Plane CO Survey can resolve gas involved in gamma-ray generation at a scale comparable to the resolution of future gamma-ray experiments, while giving insights into gas dynamics. Dense gas tracers such as CS and NH3 have proven to be useful probes of gamma-bright regions, while SiO emission can directly highlight shock-disrupted gas. We present the results of molecular spectral line observations towards supernova remnants at various stages of evolution.

Speaker: Nigel Maxted (The University of New South Wales)

MAXTED_CosPA_2016-11-29.pdf

Event: Public talk

Wednesday 30 November

Plenary

Convener: Christian Reichardt (University of Melbourne)

HouskeepingCosPA_v2.pdf

HouskeepingCosPA_v2.pptx

87 Inflation

Speaker: Prof. Misao Sasaki (Kyoto University)

Inf_cospa_MS.pdf

88 Planck CMB results

Speaker: Silvia Galli

Galli_Australia_nb.pdf

89 Cosmological surveys

Speaker: Geraint Lewis (The University of Sydney)

10:30 Coffee Break

Plenary

Convener: mihoko nojiri (KEK)

HouskeepingCosPA_v2.pdf

HouskeepingCosPA_v2.pptx

90 Astroparticle tests of dark matter theories

Speaker: Pat Scott (Imperial College)

PS_CosPA.pdf

91 Mono-X, dijet, and long-lived particle searches at the LHC

Speaker: Millie McDonald (University of Melbourne (AU))

milliem_cosPA2016_slides.pdf

92 Invisible Higgs decays, SUSY searches and BSM Higgs at the LHC

Speaker: Chia-Ming Kuo (National Central University (TW))

20161130_CosPA2016_slides.pdf

Thursday 1 December

Plenary

Convener: Antoine David Kouchner (Universite de Paris VII (FR))

HouskeepingCosPA_v2.pdf

HouskeepingCosPA_v2.pptx

93 Baryo-/Leptogenesis

Speaker: Alexander Kusenko

Kusenko, Leptogenesis, scalar fields, and magnetic fields

94 Neutrino studies in the Mediterranean: the KM3NeT/ARCA neutrino telescope

ARCA (Astroparticle Research with Cosmics in the Abyss) is the high-energy neutrino telescope being built as part of the KM3NeT deep-sea research infrastructure. Optimised for a high angular resolution to neutrinos in the TeV-PeV regime, its main physics goals are the exploration of the high-energy astrophysical neutrino signal reported by IceCube, and the discovery of Galactic neutrino sources.

Currently in Phase 1 deployment, in Phase 2 ARCA will consist of two "building blocks" deployed in the Mediterranean Sea off the coast from Capo Passero (Sicily, Italy). Each block will consist of 115 strings; each string comprises 18 optical modules, and each optical module carries 31 photo-multiplier tubes. The excellent optical properties of deep seawater allow high-resolution neutrino studies by collecting the Cherenkov light emitted along the path of charged particles produced in neutrino interactions inside or close to the detector.

An overview of the expected performances of the detector to several possible source classes will be given, together with an update of the present status of construction.

Speaker: Clancy James (University of Erlangen-Nuernberg)

cwjames_km3net_cospa2016.pdf

95 IceCube Neutrinos

The IceCube Neutrino Observatory is the world’s largest neutrino detector. Located at the South Pole, IceCube consists of a cubic kilometre of ice instrumented with 5160 photomultiplier tubes on 86 strings at a depth of 1.5-2.5 km. In this talk I will present the latest results concerning the high-energy neutrinos detected by IceCube. Plans for a next-generation IceCube detector, named IceCube-Gen2, will also be presented.

Speaker: Prof. Jenni Adams (University of Canterbury)

cospa_16_adams.pdf

10:30 Coffee Break

Plenary

Convener: Matthieu TRISTRAM (CNRS)

HouskeepingCosPA_v2.pdf

HouskeepingCosPA_v2.pptx

96 Dark energy

Speaker: Prof. Eric Linder (UC Berkeley)

LinderCOSPA16.pdf

97 Consistency checks of LCDM

Speaker: Dr Arman Shafieloo (KASI Daejeon)

Sydney_Cospa_2016.pdf

98 Inhomogeneous Cosmology

The present epoch Universe is inhomogeneous on < 100/h Mpc scales, opening up the possibility of backreaction - that average cosmic expansion is significantly different from that of the standard FLRW geometry at late epochs. Realizing this possibility means confronting unsolved open questions in general relativity, in particular the nonlocal nature of gravitational energy in coarse-graining matter and geometry. The timescape scenario is a phenomenologically viable model without dark energy which addresses these issues. In this talk I will focus on observational signatures of inhomogeneity and backreaction, including the Clarkson-Bassett-Lu (CBL) test that with Euclid satellite data should distinguish backreaction models from the concordance FLRW model in the next decade. While conceding a bet I made with Padmanabhan 10 years ago on the basis of current data, I offer a new bet on the CBL test for the coming age of "precision cosmology".

Speaker: David Wiltshire (University of Canterbury)

COSPA-DLW.pdf

Event: AP CosPA Org Council and General Assembly Joint Meeting

12:30 Lunch Break

Cosmological models

Convener: Krzysztof Bolejko (University of Oxford)

99 All-scale cosmological perturbations and screening of gravity in inhomogeneous Universe

Without exceeding the limits of the concordance cosmological model, all-scale scalar and vector perturbations of the homogeneous background are derived analytically for arbitrarily distributed inhomogeneities (discrete gravitating masses) as their nonrelativistic sources. The obtained expressions for the metric corrections converge everywhere in voids, have zero average values, and conform to Minkowski background limit and Newtonian cosmological approximation as particular cases. Moreover, the uniform matter distribution limit as one more crucial test is easily passed as well. It is rigorously proven that gravitational attraction between inhomogeneities is governed by Yukawa law, covering the whole space and coming up to take place of Newtonian gravitation, which is restricted exclusively to sub-horizon distances. The finite time-dependent screening length (amounting to 3.7 Gpc at present) is determined by the average rest mass density of nonrelativistic matter and provides natural estimates of the homogeneity scale, the upper limit of the cosmic structure dimension, and the bound to a spatial domain of probable structure development.

ApJ 825, 84 (2016)

1509.03835

Speaker: Dr Maxim Eingorn

Eingorn_Sydney_CosPA_2016.pdf

100 Uniformity of Cosmic Microwave Background as a Non-Inflationary Geometrical Effect

The concordance cosmological model involving inflation describes the Universe very well. However, strict constraints are imposed by the recent observational data on the shape of the inflaton potential, excluding a lot of inflationary scenarios. We propose an alternative interpretation of the cosmic microwave background (CMB) data. We demonstrate that in the framework of the ΛCDM model supplemented in the spherical space with an additional perfect fluid with the constant parameter −1/3 in the linear equation of state, there is an elegant solution of the horizon problem without inflation. Under the proper choice of the parameters, light travels between the antipodal points during the age of the Universe. Thus, one can suggest that the observed CMB radiation originates from a very limited space region, which explains its uniformity. We reach the agreement with the supernovae data and discuss a possibility that the Universe was not uniform at the early stage and that creation of galaxies and large scale structure is due to inhomogeneities that originated in the Big Bang. We also show that changing the amplitude of the initial power spectrum, one can adjust the proposed cosmological model to the CMB anisotropy, and that the necessary change is well inside the experimentally allowed constrains.

http://www.worldscientific.com/doi/10.1142/S0217732315300268

http://arxiv.org/abs/1511.00369

Speaker: Branislav Vlahovic (North Carolina Central University)

101 CMB Hemispherical Power Asymmetry & Noncommutative Spacetimes

In this talk, I'll start with the Cosmological Principle and its ramifications for the Cosmic Microwave Background Radiation. Mathematically speaking, statistical isotropy implies nonzero correlations between spherical harmonic coefficients $\left}$ only when $l=l^{\prime}$ and $m=m^{\prime}$. But because of the presence of Hemispherical Power Asymmetry, other correlations are also found and hence Cosmological Principle is violated.

To explain this effect a large number of models have already been given. But in our work, we were interested in the possibility of explaining it using the modified primordial power spectrum. It is argued that by introducing `some' anisotropy and/or inhomogeneity, we can explain this effect. After mathematical analysis, $l^{\prime}=l+1, m^{\prime}=m$ are concomitantly found with the usual isotropic ones. By defining a statistic and subsequent $\chi^2$ analysis, model parameters are extracted.

I'll also show that the ab initio derivation of the anisotropic primordial power spectrum can't be done in the commutative spacetimes. It is found that the same kind of form (apart from some extra correlations) can be derived in noncommutative spacetimes.

Speaker: Mr Rahul Kothari (IIT Kanpur, India)

Slides.pdf

Dark matter

Convener: Robert Foot

102 Particle Physics Models for DM-DR interactions

This talk will be based on two recent preprints:
arXiv:1608.01083
arXiv:1609.02307

Speaker: pyungwon ko (Korea Inst. for Advanced Study (KIAS))

Interacting DM-DR.pdf

103 Triplet-Quadruplet Fermionic Dark Matter

We explore a dark matter model extending the standard model particle content by one fermionic SU(2)_L triplet and two fermionic SU(2)_L quadruplets, leading to a minimal realistic UV-complete model of electroweakly interacting dark matter which interacts with the Higgs doublet at tree level via two kinds of Yukawa couplings. After electroweak symmetry breaking, the physical spectrum of the dark sector consists of three Majorana fermions, three singly charged fermions, and one doubly charged fermion, with the lightest neutral fermion serving as a dark matter candidate. A typical spectrum exhibits a large degree of degeneracy in mass between the neutral and charged fermions, and we examine the one-loop corrections to the mass differences to ensure that the lightest particle is neutral. We identify regions of parameter space for which the dark matter abundance is saturated for a standard cosmology including coannihilation channels. Constraints from precision electroweak measurements, searches for dark matter scattering with nuclei, and dark matter annihilation are important, but leave open a viable range for a thermal relic.

Speaker: Zhao-Huan Yu (University of Melbourne)

Yu_TQFDM_CosPA.pdf

104 Right-handed neutrino dark matter under the B-L gauge interaction

Right-handed neutrinos (RHNs) are widely considered as an convincing new particle that can address various issues in the standard model (SM) such as the origin of neutrino mass, the existence of dark matter, and baryon asymmetry of the universe.
On the other hand, the gauge principle plays a key role to understand nature, which is empirically supported by the success of the SM so far.
In the light of this success, the B-L gauge symmetry is one of the most attractive symmetries that offers three RHNs which are the minimal set to successfully address above-mentioned issues.
In this talk, I will discuss various RHN dark matter scenarios under the B-L gauge interaction, and emphasize the sub-electroweak scale Z' case that can be tested by forthcoming beam dump experiments.

Speaker: Kunio Kaneta

kaneta_CosPA2016.pdf

105 Probing mixed complex scalar WIMP dark matter

We discuss phenomenology of models extended by introducing
an isospin doublet scalar and a complex singlet scalar.
In such models, the lighter state of mixed neutral scalars can be WIMP candidate.
We point out that some WIMP mass regions are consistent with results of dark matter searches
as well as the limit on the dark matter relic density.
We show that these allowed regions can be investigated at future collider experiments
and dark matter direct detections.

Speaker: Akiteru Santa (University of Toyama)

161201_SANTA.pdf

Gravity and gravitational waves

Convener: Shinji Tsujikawa (Tokyo University of Science)

106 Gravitation, Causality, and Quantum Consistency

We discuss the role of consistency with causality and quantum mechanics in determining the properties of gravity. We begin by constructing theories of interacting massless spin 2 particles -- gravitons. One theory involves coupling the graviton with the lowest number of derivatives to matter, the other theories involve coupling the graviton with higher derivatives to matter. The first theory requires an infinite tower of terms for consistency, which is known to lead to general relativity. The other theories only require a finite number of terms for consistency, which appear as an entire new class of theories of massless spin 2. We recap the causal consistency of general relativity and show that in general this fails for the new class of theories. This appears to be a deep reason for minimally coupling the graviton with the lowest number of derivatives. Then, as a causal modification of general relativity, we discuss the so-called $F(\mathcal{R})$ theories, which have interesting applications to cosmology including inflation and dark energy. We show that, unlike general relativity, these theories do not possess the requisite counter-terms to be consistent quantum effective field theories. Together this helps to remove some of the central assumptions made in deriving general relativity.

Speaker: Prof. Mark Hertzberg (Tufts University)

Hertzberg.Gravity.Causality.Quantum.CosPA.pdf

107 Black Hole Thermodynamics, Expanding Universe and Dark Energy

Cai and Kim [JHEP02(2005)050] proposed an interpretation of black hole thermodynamics for an expanding universe in Einstein, Gauss-Bonnet and Lovelock gravity. There have been since then numerous applications and interpretions of the entanglement entropy to the universe. In this talk, the recent progress in this direction will be critically reviewed and revisited from the view point of current observational data. In parcular, an emphasis will be put on the relation with the dark energy.

Speaker: Prof. Sang Pyo Kim (Kunsan National University)

108 Relation between gauge fixing and DOFs in scalar-tensor theories

First, I describe the motivation of this work and then introduce a simple toy model which is useful to understand the essential point of our theorem.

Next, I show that the following two sets of equations are equivalent if the gauge fixing is complete:
One is the Euler-Lagrange equations derived from the original action supplemented with the gauge-fixing conditions, and the other is the Euler-Lagrange equations derived from the gauge-fixed action with Lagrange multipliers.

Finally, I provide an application of the theorem to the case of homogeneous isotropic universe in scalar-tensor theories.

Speaker: Kazufumi Takahashi (RESCEU, The University of Tokyo)

TakahashiCosPA2016.pptx

109 Dynamical brane backgrounds

Time dependent brane solutions of supergravity have been
of particular importance in the advances of gravity theory.
We review the current status of these "dynamical" brane solutions
in higher-dimensional supergravity theories and discuss primarily
the gravitational aspects of p-branes and their relatives in various
dimensions. We also comment the D-brane and M-brane solutions
in ten and eleven dimensions, which provide a number of interesting
black objects, cosmological models, supersymmetric breaking,
and the violation of cosmic censorship.

Speaker: Kunihito Uzawa (Kwansei Gakuin University)

Kunihito Uzawa.pdf

110 Special relativistic hydrodynamics with gravitation

The special relativistic hydrodynamics with Newtonian gravity is hitherto unknown in the literature. Whether such an asymmetric combination is possible was unclear. Here, the hydrodynamic equations with Poisson-type gravity considering fully relativistic velocity and pressure under the weak gravity and the action-at-a-distance limit are consistently derived from Einstein's general relativity. Analysis is made in the maximal slicing where the Poisson's equation becomes much simpler than our previous study in the zero-shear gauge. Also presented is the hydrodynamic equations in the first post-Newtonian approximation, now under the {\it general} hypersurface condition. Our formulation includes the anisotropic stress.

Speaker: Jai-chan Hwang

CosPA-SRHG-Hwang-20161201.pdf

Inflation and early universe cosmology

Convener: Andrew Fowlie (Monash University)

111 Testing the low scale seesaw and leptogenesis

Heavy neutrinos with masses below the electroweak scale could simultaneously generate the light neutrino masses via the seesaw mechanism and the baryon asymmetry of the universe via leptogenesis. The requirement to explain both imposes constraints on the mass spectrum of the heavy neutrinos, their flavour mixing pattern and $CP$ properties. If any heavy neutral leptons are discovered in the future, it will be possible to use a combination of different observables in order to assess whether these are indeed the common origin of the light neutrino masses and the baryon asymmetry of the universe.

Speaker: Dario Gueter (Max Planck Institute for Physics)

CosPA16_DarioGueter.pdf

112 Electroweak baryogenesis in the Z3-invariant NMSSM

The NMSSM has the attractive features of being able to provide at least a partial solution to the little hierarchy problem through the introduction of a guage singlet. Its usefulness in electroweak baryogenesis is more pronounced - with the singlet being useful to catalyze a boost in the strength of the EWPT without conflicting with collider constraints. Furthermore, interactions between the singlino-higgsino and the space time varying vacuum provide a source of CP violation not present in the MSSM and virtually unconstrained by negative searches for permanent EDMs. We present an in depth analysis of the prospects of electroweak baryogenesis within the NMSSM.

Speaker: Graham White (Monash University)

GW_cospa.pdf

113 A Strong Electroweak Phase Transition from the Inflaton Field

We study a singlet scalar extension of the Standard Model. The singlet scalar is coupled non-minimally to gravity and assumed to drive inflation, and also couple sufficiently strongly with the SM Higgs field in order to provide for a strong first order electroweak phase transition. Requiring the model to describe inflation successfully, be compatible with the LHC data, and yield a strong first order electroweak phase transition, we identify the regions of the parameter space where the model is viable. We also include a singlet fermion with scalar coupling to the singlet scalar to probe the sensitivity of the constraints on additional degrees of freedom and their couplings in the singlet sector. We also comment on the general feasibility of these fields to act as dark matter.

Speaker: Tommi Tenkanen

CosPA16_Tommi_Tenkanen.pdf

114 Efficient perturbative determination of bubble wall profiles

We present semi-analytic techniques for finding bubble wall profiles during a first order phase transitions with multiple scalar fields. Our method involves reducing the system to a single-field problem, and then creating a convergent series of perturbative corrections to an analytic ansatz solution.

Speaker: Dr Sujeet Akula (Monash University)

akula-cospa2016.pdf

115 The effects of monopoles on the electroweak phase transition

Electroweak monopoles are spherically symmetric configurations of the gauge fields that derive their stability from their topological nature. This talk discusses the effect of regularised Cho-Maison monopoles on the strength of the electroweak phase transition and the implications of this on electroweak baryogenesis.

Speaker: Suntharan Arunasalam (University of Sydney)

CosPA16_Suntharan_Arunasalam.pdf

15:40 Coffee Break

Dark matter

Convener: Dr Juan Herrero Garcia (University of Adelaide - CoEPP)

116 Relic Abundance in Secluded Dark Matter Scenario with Massive Mediator

The relic abundance of the dark matter (DM) particle $d$
is studied in a secluded DM scenario, in which the $d$ number
decreasing process dominantly occurs not through the pair annihilation
of $d$ into the standard model particles, but via the $dd \to mm$
scattering process with a subsequently decaying mediator particle $m$.
It is pointed out that the cosmologically observed relic abundance of DM
can be accomplished even with a massive mediator having a mass $m_m$
non-negligibly heavy compared with the DM particle mass $m_d$.
In the degenerated $d$-$m$ case
($m_d=m_m$),
the DM relic abundance is realized by adjusting
the $dd \to mm$ scattering amplitude large enough and by choosing
an appropriate mediator particle life-time.
The DM evolution in the early universe exhibits characteristic
"terrace" behavior, or two-step number density decreasing behavior,
having a ``fake'' freeze-out at the first step.
Based on these observations, a novel possibility of the DM model
buildings is introduced
in which the mediator particle $m$ is unified with the DM particle
$d$ in an approximate dark symmetry multiplet.
A pionic DM model is proposed to illustrate this idea
in a renormalizable field theory framework.

S. Okawa, M. Tanabashi and M. Yamanaka,
``Relic Abundance in Secluded Dark Matter Scenario with Massive Mediator,''
arXiv:1607.08520 [hep-ph].

Speaker: Masato Yamanaka (Kyoto Sangyo University)

CosPa2016_Yamanaka.pdf

CosPa2016_Yamanaka.pptx

117 A map of the non-thermal WIMP

We study the effect of elastic scattering on the non-thermally produced WIMP dark matter and its phenomenological consequences. The non-thermal WIMP becomes important when the reheating temperature is well below the freeze-out temperature. In the usual paradigm, the produced high energetic dark matters are quickly thermalized due to the elastic scattering with background radiations. The relic abundance is determined by the thermally averaged annihilation cross-section times velocity at the reheating temperature. In the opposite limit, the initial abundance of produced dark matters is small enough so they do not annihilate, and the relic density is determined by the branching fraction of the heavy particle. We study the regions between these two limits, and show that the relic density could be sensitive not only to the annihilation rate, but also to the elastic scattering rate. Especially, the relic abundance of p-wave annihilating dark matter crucially depends on the elastic scattering rate because the annihilation cross-section is sensitive to the dark matter velocity. We categorize the parameter space into several regions where each region has distinctive mechanism for determining the relic abundance of the dark matter at the present Universe. The consequence on the (in)direct detection is also studied.

Speaker: Chang Sub Shin (Rutgers University)

CosPA2016_Nonthermal_WIMP_1201.pdf

118 Determining the Local Dark Matter Density

An accurate determination of the local dark matter (DM) density is crucial to interpreting data from direct detection and certain indirect detection experiments, as it is degenerate with the DM-nucleon interaction strength. Here I give an update to our ongoing project to make a determination of the local DM density. Our method uses the positions and velocities of a set of tracer stars extending upwards out of the Milky Way disc, to which we fit a baryon and dark matter mass model using Bayesian nested sampling. The framework we have set up holds the promise of allowing us to minimise the number of assumptions needed, and thus determine the local DM density accurately and with a full quantification of its uncertainty. We have begun to apply our method to data from SDSS, and also plan to apply it to Gaia data.

Speaker: Hamish Silverwood (University of Amsterdam)

Silverwood_2016_CosPA_v1.pdf

Inflation and early universe cosmology

Convener: Geraint Lewis (The University of Sydney)

119 Resurrection of large lepton number asymmetries and their cosmological implications

It will be shown that, even if Big Bang Nucleosynthesis constrains the asymmetry of electron neutrinos to be of or less than $\mathcal{O}(10^{-3})$, asymmetries of muon- and tau-neutrinos can be large and lead to $\Delta N_{\rm eff}=\mathcal{O}(0.1-1)$ as the number of extra neutrino species. Also, it will be shown that $\Delta N_{\rm eff}$ should be estimated from contributions of neutrino mass-eigenstates instead of neutrino flavor-eigenstates.

Speaker: Wanil Park

120 Adiabatic Invariance of I-balls/Oscillons

Scalar fields are know to have various roles in the early Universe such as inflaton. Among of them, some real scalar fields are known to fragment into spatially localized and long-lived solitons called oscillons or I-balls. We prove the adiabatic invariance of the oscillons/I-balls for a potential that allows periodic motion even in the presence of non-negligible spatial gradient energy. We show that such potential is uniquely determined to be the quadratic one with a logarithmic correction, for which the oscillons/I-balls are absolutely stable. For slightly different forms of the scalar potential dominated by the quadratic one, the oscillons/I-balls are only quasi-stable, because the adiabatic charge is only approximately conserved. We check the conservation of the adiabatic charge of the I-balls in numerical simulation by slowly varying the coefficient of logarithmic corrections. This unambiguously shows that the longevity of oscillons/I-balls is due to the adiabatic invariance.

Speaker: Naoyuki Takeda

CosPa2016_NaoyukiTakeda.pdf

121 Production of axion CDM from strings and domain-walls

Predicted by the Peccei-Quinn (PQ) mechanism, that solves the Strong CP problem in QCD, axion is one of the most promising candidates of dark matter. In my talk, I will be reviewing recent developments in estimation of the abundance of axion CDM from topological defects. When the reheating temperature is higher than the PQ energy scale, the symmetry breaking of U(1)_{PQ} takes place in the early Universe and axion cosmic strings form, which is followed by the formation of axion domain-walls at the QCD phase transition. From the cosmological network of these defects, axions are copiously produced and contribute to the current energy density of CDM in the Universe. Based on field-theoretic simulations, we can follow the cosmological evolution of these defects and axions radiated therefrom. In conjunction with innovative analysis techniques we have introduced, our massive simulations allow to estimate the axion abundance more precisely than ever before. We derive a constraint on the PQ energy scale from the axion CDM abundance and discuss implications for cosmological scenarios.

Speaker: Dr Toyokazu Sekiguchi (IBS/CTPU)

Toyokazu_Sekiguchi.pdf

122 Natural Inflation with Hidden Scale Invariance

We propose a new class of natural inflation models based on a hidden scale invariance. In a very generic Wilsonian effective field theory with an arbitrary number of scalar fields, which exhibits scale invariance via the dilaton, the potential necessarily contains a flat direction in the classical limit. This flat direction is lifted by small quantum corrections and inflation is realised without need for an unnatural fine-tuning. In the conformal limit, the effective potential becomes linear in the inflaton field, yielding to specific predictions for the spectral index and the tensor-to-scalar ratio, being respectively: ns−1≈−0.025(N⋆/60)−1 and r≈0.0667(N⋆/60)−1, where N⋆≈30−65 is a number of efolds during observable inflation. This predictions are in reasonable agreement with cosmological measurements. Further improvement of the accuracy of these measurements may turn out to be critical in falsifying our scenario.

Speaker: Shelley Liang (The university of Sydney)

SI inf.pdf

Particle physics

Convener: Hai-Yang Cheng (Academia Sinica)

123 MeV scale leptonic force for cosmic neutrino spectrum and muon anomalous magnetic moment

Characteristic patterns of cosmic neutrino spectrum reported by the　IceCube
Collaboration and　long-standing inconsistency between theory and experiment
in muon anomalous magnetic moment　are simultaneously explained by an extra
leptonic force mediated by a gauge field with a mass of the
MeV scale. With different assumptions for redshift distriution of
cosmic neutrino sources, diffuse　neutrino flux is calculated with the
scattering between cosmic neutrino and cosmic neutrino back-ground through
the new leptonic force. Our analysis sheds light on a relation among lepton physics
at the three different scales, PeV, MeV, and eV, and provides possible clues to the distribution of　sources of cosmic neutrino and also to neutrino mass spectrum

Speaker: Prof. Joe Sato

CosPA-Sato.pdf

124 Search for a light L_{\mu}-L_{\tau} gauge boson at Belle II

In previous work, it was found that if L_{\mu}-L_{\tau} massive Z' has a MeV-scale mass, muon g-2 problem and IceCube gap can be simultaneously explained. Then, I have studied the detectability of Z' at the future Belle II experiment. I'll propose a detectability of Z' through a one photon + missing process.

Speaker: Ms Shihori Hoshino (Saitama University)

CosPA2016_hoshino.pdf

125 Partial Gauge Invariant SM

We argue that an exact gauge invariance may disable some generic features of the Standard Model which could otherwise manifest themselves at high energies. One of them might be related to the spontaneous Lorentz invariance violation (SLIV) which could provide an alternative dynamical approach to QED and Yang-Mills theories with photon and non-Abelian gauge fields appearing as massless Nambu-Goldstone bosons. To see some key features of the new physics expected we propose partial rather than exact gauge invariance in an extended SM framework. This principle applied, in some minimal form, to the weak hypercharge gauge field Bµ and its interactions leads to SLIV with B field components appearing as the massless Nambu-Goldstone modes, and provides a number of distinctive Lorentz beaking effects. Being naturally suppressed at low energies they may become detectable in high energy physics and astrophysics. Some of the most interesting SLIV processes are considered in significant detail.

Speaker: Zurab Kepuladze (Andronikashvili Institute of Physics, TSU)

Partial Gauge Invariant SM-CosPA-Kepuladze.pdf

126 Radiative neutrino mass generation for a dimension 7 gauge-invariant operator and its implication for charge lepton flavor violation

In this work, we construct a two-loop radiative Majorana neutrino mass
model based on a dimension 7 gauge-invariant operator that violates the
lepton number by two units. The UV completion in this model includes a
scalar leptoquark doublet with hypercharge 1/6 and an additional vector-like
lepton doublet. It is shown that the neutrino mass matrix is proportional to
the masses of the heavy charged vector-like lepton and the top and bottom
quarks. In this model, we predict the rare charge lepton violation processes.
Integrating out the heavy charged and neutral components of vector-like
lepton induces a non-unitary PMNS mixing matrix.

Speaker: Mr Bahman Ghadirian (The University of Sydney)

Presentation_Bahman Ghadirian.pdf

Event: Conference Dinner

Friday 2 December

Plenary

Convener: Csaba Balazs (Monash University)

HouskeepingCosPA_v2.pdf

HouskeepingCosPA_v2.pptx

127 Fermi LAT

Speaker: Dr Regina Caputo (University of California, Santa Cruz)

Caputo-CosPA-FermiLAT.pdf

128 The Cherenkov Telescope Array: A TeV Gamma-Ray Observatory

Speaker: Gavin Rowell (University of Adelaide)

gpr-CTA-v1.pdf

129 Dark Energy with the Dark Energy Survey

The Dark Energy Survey (DES) is in its fourth year of a five year observing program. We’re on our way to mapping 300 million galaxies and measuring 3000 type Ia supernovae for dark energy studies as well as monitoring 800 Active galaxies so we can use reverberation mapping to measure supermassive black hole masses across the last 12 billion years (to z~4). Over 525 nights DES combines a wide-field imaging survey with a narrower time-lapse survey. OzDES are following up the narrow region with 100 nights of spectroscopy on the Anglo-Australian Telescope. I’ll give an update of progress, give some early results, and show how we expect to use this data to constrain dark energy through type Ia supernovae, gravitational lensing, and Baryon Acoustic Oscillations.

Speaker: Prof. Tamara Davis (University of Queensland)

10:30 Coffee Break

Plenary

Convener: Prof. Sang Pyo Kim (Kunsan National University)

HouskeepingCosPA_v2.pdf

HouskeepingCosPA_v2.pptx

130 SABRE

Speaker: Elisabetta Barberio (University of Melbourne (AU))

131 Outlook for the discovery of new physics

Speaker: Raymond Volkas (The University of Melbourne)

Volkas-CosPA2016.pdf

132 Closing