Talks 2015

DAY 21st                                                                                                                                                                                                       

Title: "Black holes in binary systems and discovery of the first Be/BH system"

Author: Marc Ribó (University of Barcelona)

Abstract: Around 20 stellar-mass black holes (BHs) have been discovered forming part of binary systems in the Milky Way and in nearby galaxies. Their spectral energy distribution and variability at different wavelengths has allowed to build up a common phenomenological picture. While most of these BH have been discovered through X-ray emission from the accretion of gas from their binary companions, recent studies have allowed us to discover the first of such systems in a quiescent state. I will introduce the topic of BH in binary systems and focus on this recent discovery, emphasyzing what we have learned from multi-wavelength studies of this system. I will also comment on recent research on similar systems containing either BHs or Be stars that has been possible thanks to this discovery.

 

Title: "Chiral transport phenomena"

Author: Cristina Manuel

Abstract: For systems made up by chiral fermions the conventional hydrodynamics and transport equations are modified, leading to new  transport phenomena related to the quantum anomalies of quantum field theories. I will explain how to derive  these equations and effects from simple semi-classical arguments, and focus on the dynamical evolution of systems with an initial chiral fermion imbalance.  I will emphasize that these ideas are relevant for systems made up of quasi-massless fermions, that is, with applications in cosmology, astrophysics, and condensed-matter physics (with the new  recently discovered materials, the so called Weyl semimetals).  It is believed that these ideas might be useful to explain the generation of magnetic fields with magnetic helicity in cosmological and astrophysical scenarios.

 

Title: "Rare B decays at LHCb"

Author: Míriam Calvo (La Salle, URL)

Abstract: In absence of direct signs of new physics at the LHC, rare decays of heavy flavoured particles provide an ideal laboratory to look for deviations from the Standard Model and explore an energy regime beyond the LHC reach. Here, recent results from the LHCb experiment are presented, with a particular focus on electroweak penguin-mediated b→s transitions and radiative B decays.

 

Title: "Supernova-Driven Turbulence and the Formation and Dynamics of Star-Forming Clouds"

Author: Paolo Padoan (ICREA & ICC, University of Barcelona)

Abstract: The origin of molecular cloud (MC) turbulence has not been firmly established, as several processes may contribute. I will argue that supernova (SN) explosions are the best candidate for both the formation of MCs and their turbulence. Based on the analysis of one of largest simulations of SN-driven ISM turbulence to date, on a scale of 250 pc, I will discuss the nature of the turbulence, the formation of MCs, the probability distribution of their lifetimes, and other general MC properties. I will also present a comparison of such results with observational data from the Outer Galaxy Survey of MCs.

 

Title: "Next-to-leading order terms in chiral SU(3) Lagrangian"

Author: V.K. Magas, A. Feijoo, E. Oset, A. Ramos (ICREA & ICC, University of Barcelona)

Abstract: We study the meson-baryon interaction in S-wave in the strangeness S=-1 sector using a chiral SU(3) Lagrangian extended to next-to-leading order (NLO). Our model has 7 new parameters, related to NLO terms, which are fitted to the large set of experimental data available for different two-body channels. We pay particular attention to the Cascade production reactions, where the effect of the NLO terms is very important. Finally, the developed model is applied to simulate the weak decay of the Λb into states containing a J/Ψ and meson-baryon pairs, which are now under investigation in CDF and LHCb collaborations.

 

Title: "CMB Distortions due to peculiar motion and intrinsic Anomalies"

Author: Alessio Notari (Universitat de Barcelona)

Abstract: I show that the CMB is significantly affected and distorted in frequency by our proper motion and review various methods to measure this effect. I also discuss several Anomalies possibly present in the Planck CMB sky and their overlap with motions-induced effects: hemispherical power asymmetry, dipolar modulation and quadrupole-octupole alignments.

 

Title: "What is controlling the fragmentation process in the infrared dark cloud G14.225-0.506?"

Author: Gemma Busquet (Institut de Ciències de l'Espai (CSIC-IEEC)) 

Abstract: Filaments are ubiquitous structures in star-forming complexes, which often intersect in high-density regions associated with star formation, know as hub-filament systems. Despite filaments having been recognized more than 30 years ago, the ubiquity of such structures in star-forming regions, which has been recently highlighted by Herschel programs, has brought special attention to their formation mechanism and their role in the star formation process. What is/are the physical agent(s) responsible of shaping the interstellar material into filamentary structures? How do they evolve? How filamentary structures fragment to form dense cores, and hence form stars?

With the aim of investigating the origin and evolution of filamentary structures and their subsequent fragmentation we started an observational project with different telescopes towards the Infrared Dark Cloud G14.225-0.506, performing a multi-wavelength and multi-scales study of the cloud. I will present spectroscopic results of the dense gas (e.g. NH3) material of the cloud, which unveil a network of filaments, constituting two hub-filament systems identified using combined interferometric (VLA) and single-dish (Effelsberg) observations. This large network of filaments seems to be separated into two main velocity components, separated by 3 km/s, which overlap in the hubs. I will show the main physical properties of these filaments and discuss the possible origin of such structures.The two hubs contain the main sites of star formation activity in the cloud, and present a different level of fragmentation as revealed in the high resolution SMA images. I’ll discuss the interplay between turbulence, magnetic fields, density, and UV radiation feedback in the fragmentation process.

 

Title: "Quarkonium hybrids in Effective Field Theory"

Author: Jaume Tarrús Castellà (Technische Universität München) 

Abstract: Quantum field theory systems with several well separated scales are better described using Effective Field Theories (EFT). One of such systems are the bound states of a heavy quark-antiquark pairs, the so-called Quarkonium states. In the last decade new, unexpected, quarkonium states close and above open flavor thresholds have been discovered. These states are interesting because they are candidates for unconventional hadronic states, for example, tetraquark states (clustered in different ways depending on the model) or quarkonium hybrids. In this talk we present our study for quarkonium hybrids, states made on a heavy quark-antiquark pair and a gluonic excitation, within the framework of nonrelativistic EFT of QCD.

 

Title: "An operational approach to Bell inequalities"

Author: Daniel Alsina (UB)

Abstract: Bell inequalities were a revolutionary discovery to better understand the intrinsic non-local behavior of quantum mechanics. In general they have been studied in relation to well-known entangled states. We focus instead on a not so well-known operational approach, trying to grasp the fundamental cause of their violation in an analytical way.

 

 

Title: "Studying the Expansion of the Universe with quasar spectra"

Author: Andreu Font-Ribera (Lawrence Berkeley National Laboratory)

Abstract: After six years of observations, the Baryon Oscillation Spectroscopic Survey (BOSS) ended last year, and all its data is already public (SDSS Data Release 12). During these years, it has used the SDSS telescope to obtain spectra of 1.5 million galaxies to get very accurate measurements of the Baryon Acoustic Oscillations (BAO) scale at redshift z ~0.5. At the same time, BOSS observed over 184 000 high redshift quasars (z>2.15) with the goal of detecting the BAO feature in the clustering of the intergalactic medium, using a technique known as the Lyman alpha forest (LyaF).
In this talk I will overview several results from the LyaF working group in BOSS, including the measurement of BAO at z=2.4 both from the auto-correlation of the LyaF (Delubac et al. 2015), and from its cross-correlation with quasars (Font-Ribera et al. 2014). From the combination of these studies we are able to measure the expansion rate of the Universe 11 billion years ago with a 2% uncertainty.

 

DAY 22nd                                                                                                                                                                                                       

 

Title: "Probing electroweak symmetry breaking with Higgs pair production at the LHCB"

Author: Juan Rojo  (University of Oxford)

Abstract:  The measurement of Higgs pair production is one of the cornerstones of the LHC program for the next years. Double Higgs production provides a crucial window to the electroweak symmetry breaking mechanism and has unique sensitivity to the Higgs trilinear coupling. In this talk, I study the feasibility of a measurement of Higgs pair production at the LHC in the final state with four bottom quarks. The analysis is based on a combination of traditional cut-based methods with state-of-the-art multivariate techniques. Our results indicate that this final state  alone should allow for the observation of double Higgs production at the High Luminosity LHC, and even a first measurement at Run II might within reach.

 

Title: "Getting ready for the scientific exploitation of Gaia data"

Author: Merce Romero-Gomez  (ICCUB-IEEC)

Abstract:  Gaia is an ambitious mission to chart a three-dimensional map of our Galaxy. In this talk we will first make a short review of the current status. As an example, by November 2015, Gaia has accumulated about 340 billion positional or astrometric measurements, 68 billion brightness or photometric data points, and 6.7 billion spectra. We will put special emphasis on the first and second Gaia data releases, which are foreseen by mid-2016 and mid-2017, respectively. In this context, we will show the work done in our team in galactic dynamics to first exploit Gaia data. We have developed new methods to use with the upcoming data, from a novel method to bracket the corotation radius in galaxy disks, to a method to determine the nature of spiral arms and its connection to the manifolds. We will show how the Galactic bar and warp will be seen by Gaia, and how to disentangle their kinematic imprint to progress on the dynamical evolution of these structures. An overview of the WEAVE multiobject spectrograph contribution to the 6D map of the Milky Way will be presented.

 

Title: "Neutron star microscopy"

Author: Arnau Rios (University of Surrey)

Abstract:  Neutron stars are routinely observed with a variety of astronomical tools. A microscopic theoretical description of these objects, however, poses several challenges. For one, these are the densest gravitationally stable systems of the Universe, subject to exceptionally large magnetic fields and isospin extremes that are well beyond any nuclear physics experiment. Nuclear many-body theory can help provide a consistent description of a range of neutron star observables. In this talk, I will describe on-going efforts in providing a microscopic account for neutron star observations, using both density functional and beyond-mean-field many-body techniques.

 

Title: "Heavy Quarkonium magnetic dipole transitions in pNRQCD"

Author: Antonio Pineda (UAB & IFAE-BIST)  

Abstract: We compute the magnetic dipole transitions between low lying Heavy Quarkonium states in a model independent way. We use the weak-coupling version of the effective field theory named potential NRQCD with the static potential exactly incorporated in the leading order Hamiltonian. We also resum the large logarithms associated to the heavy quark mass scale. The effect of the new power counting is found to be large and the exact treatment of the soft logarithms of the static potential makes the factorization scale dependence much smaller. The convergence for the bottomonium ground state is quite good, and also quite reasonable for the charmonium ground state and the P-wave bottomonium state. For all of them we give solid predictions. For the 2S decays the situation is less conclusive, yet our results are perfectly consistent with existing data.

 

Title: "Eta Carinae: a laboratory for cosmic ray acceleration"

Author: Víctor Zabalza (University of Leicester)  

Abstract: Even though supernova remnants are considered to be the source of the bulk of galactic cosmic rays, their long dynamical timescales (of hundreds of years) mean that we can only observe them as snapshots of the acceleration process. Colliding-wind binaries, in which the wind of two massive stars interact to form strong non-relativistic shocks, provide an ideal environment to investigate particle acceleration over the dynamical timescales of a single system. In this talk I will describe the application of a semi-analytic non-linear diffusive shock acceleration scheme to explain the gamma-ray emission from Eta Carinae.
Eta Carinae is the only colliding-wind binary system for which non-thermal emission is detected from hard X-rays to high-energy gamma rays. The gamma-ray spectrum exhibits two spectral features that can be interpreted as emission originating from protons accelerated in the shocks of the two distinct stellar winds. We have found that Eta Carinae is an efficient gamma-ray emitter because of its very particular properties: the primary wind shock is highly radiative and acts as a cosmic ray calorimeter, and the secondary wind shock is adiabatic, allowing for acceleration of protons up to very high energies that emit gamma-rays when the two winds are turbulently mixed.