Physics Seminars 2020/2021

Scheduled talks

27 May 2021

Speaker: Viktor Svensson (Szkoła Doktorska NCBJ)

Title: Divergent series and hydrodynamics

Abstract:

Hydrodynamics is a very useful theory of near equilibrium dynamics, but it is far from obvious what “near equilibrium” means in practice. Central to the formulation of hydrodynamics is a perturbative series, the gradient expansion. The applicability of hydrodynamics should be related to how well this perturbative expansion works. Many studies have shown that it is actually a divergent series. In this seminar, I’ll talk about why it diverges, and why this does not spell the end of hydrodynamics.

20 May 2021

Speaker: Andrea Bevilacqua (Szkoła Doktorska NCBJ)

Title: κ-deformed complex fields and discrete symmetries

Abstract:

In this talk I will briefly describe a construction of κ-deformed complex scalar field theory with the objective of shedding light on the way discrete symmetries and CPT invariance are affected by the deformation.

It is commonly expected that the usual description of spacetime as a smooth manifold is no longer reliable as we approach the Planck scale when quantum effects of the geometry can no longer be neglected. Since the prehistory of research on quantum gravity, noncommutativity of spacetime has been advocated as a possible way to effectively model quantum gravitational effects in regimes of negligible curvature. A widely studied incarnation of this idea suggests that the scale of noncommutativity should be seen as an  observer-independent length scale and that, in order to accommodate such a fundamental scale, ordinary relativistic symmetries should be deformed in such a way that they should reproduce the usual Poincaré algebra in the limit of vanishing noncommutativity. The κ-Poincaré algebra is an example of such deformation.

After a brief introduction to the formalism and the involved quantities, I will introduce the action and I will proceed to the calculation of the equations of motion (EOM). I will then discuss CPT transformation of the fields and present the translation charges, which will lead to a discussion of the one-particle states. I will then conclude with some comments and prospects for the future.

13 May 2021

Speaker: Piotr Kalaczyński (Szkoła Doktorska NCBJ)

Title: Comparison of the measured atmospheric muon rate with Monte Carlo simulations and sensitivity study for detection of prompt atmospheric muons with KM3NeT

Abstract:

The KM3NeT Collaboration has successfully deployed the first detection units of the next generation undersea neutrino telescopes in the Mediterranean Sea at the two sites in Italy and in France. The data sample collected between December 2016 and January 2020 has been used to measure the atmospheric muon rate at two different depths under the sea level: 3.5 km with KM3NeT-ARCA and 2.5 km with KM3NeT-ORCA. Atmospheric muons represent an abundant signal in a neutrino telescope and can be used to test the reliability of the Monte Carlo simulation chain and to study the physics of extensive air showers caused by highly-energetic primary nuclei impinging the Earth’s atmosphere. At energies above PeV the contribution from prompt muons, created right after the first interaction in the shower, is expected to become dominant, however its existence was not yet experimentally confirmed. In this talk data collected with the first detection units of KM3NeT are compared to Monte Carlo simulations based on MUPAGE and CORSIKA codes. The main features of the simulation and reconstruction chains are discussed and presented. Additionally, sensitivities of both KM3NeT-ARCA and KM3NeT-ORCA to the prompt muon component are evaluated using CORSIKA code.

6 May 2021

Speaker: Grzegorz Żarnecki  (Szkoła Doktorska NCBJ)

Title: Muon antineutrino single charged pion production cross-section measurement.

Abstract:

The goal of the presented analysis is the measurement of the muon antineutrino single charged pion production interactions on CH in the T2K near detector ND280. This interaction mode is the second largest at T2K energies and studies are ongoing to include such events in T2K oscillation analyses. For this reason, a more detailed understanding of this interaction channel using near detector data becomes vital. The measurement will be a double differential cross-section in lepton kinematics and will be extracted using a binned likelihood fit. The event selection strategy developed for this analysis along with the validation studies performed to check the analysis robustness are discussed in this presentation.

29 April 2021

Speaker: Anatolii Koval  (Szkoła Doktorska NCBJ)

Title: How does one look inside of the proton?

Abstract:

Presently Generalized Parton Distributions allow us novel three-dimensional description of the proton structure when both transverse and longitudinal degrees of freedom are taken into account. A tool to experimentally constraint GPDs is Deeply Virtual Compton Scattering. Main steps in extracting DVCS cross-section in the framework of COMPASS experiment are discussed in detail hinting path towards the proton tomography.

22 April 2021

Speaker: Krzysztof Jodłowski  (Szkoła Doktorska NCBJ)

Title: Looking for Beyond Standard Model short-lived particles with secondary production

Abstract:

Many Beyond Standard Model (BSM) physics scenarios contain new long-lived particles (LLPs), leading to interesting experimental signatures such as e.g. highly-displaced decay signatures. Examples of such minimal models are so-called portals which include coupling of New Physics particle to SM particles through a renormalizable interaction. Going beyond such simple realisations of BSM physics, one can introduce non-minimal particle content where lighter particle can upscatter into heavier one in front of the detector, leading to interplay between short and long-lived regimes. We illustrate the prospects of such searches in FASER, MATHUSLA and SHiP for a representative models with inelastic dark matter, neutrino dipole portal and dark neutrino portal, among others. We also study signatures consisting of scattering off electrons or nuclei in tungsten detector followed by the decay outside both tungsten detector and the decaying vessel or inside tungsten detector, respectively.

15 April 2021

Speaker: Michał Mazurek  (Szkoła Doktorska NCBJ)

Title: New Software Technologies at the LHCb Experiment

Abstract:

The LHCb Experiment is one of the largest detectors located at the Large Hadron Collider (LHC) at CERN (The European Organization for Nuclear Research). With the data collected during LHC Run 1 and Run 2, the LHCb Experiment has successfully performed a large number of measurements in heavy flavour physics. In order to perform further measurements with higher precision, the LHCb Experiment is currently installing a major detector upgrade for Run 3 of data taking so that it will be able to process events with 5 times higher luminosity. It is also planning a further upgrade with another increase in luminosity by a factor of 5 to 10. Higher capacity in data storage, computing power, and data processing is needed to prepare the experiment for the changes in Run 3. The whole software of the experiment is being adapted to work in a multithreaded environment in order to exploit as many as possible of the available computing resources. Moreover, new software technologies have to be introduced in order to produce a sufficient number of Monte Carlo samples. In this talk, I am going to present recent investigations on how to integrate deep learning-based fast simulation techniques in the LHCb Gauss simulation framework and a new approach to cluster reconstruction in the electromagnetic calorimeter using convolutional neural networks.

8 April 2021

Speaker: Alice Boldrin (Szkoła Doktorska NCBJ)

Title: Dirac method in Bianchi I

Abstract:

Observational data indicates that the Universe has emerged from its primordial phase in a very peculiar state: as a patch of flat, isotropic and homogeneous space furnished with small adiabatic density perturbations with a nearly scale-invariant amplitude spectrum.  Our goal is to construct a theory of the primordial universe based on the assumption that it was dominated by quantum gravity effects, which led the Universe to avoid the initial singularity. Presently available quantum frameworks usually assume primordial isotropy. The driving idea behind this work is that alternative frameworks need to possess less primordial symmetries. In particular we will start by assuming a non-isotropic Universe which eventually will be described by the Bianchi IX metric. In this presentation I will focus on the first steps needed to reach our goals. I will explain how we can obtain a Hamiltonian formulation for a Bianchi I Universe, which is a homogeneous and anisotropic Universe whose description is simpler that the one needed for Bianchi IX. After a rather technical introduction I will present the Dirac method, how and why it is useful. Finally I will show our results focusing on the difference between a Bianchi I Universe and a FLRW one.

25 March 2021

Speaker: Mahmoud Hamed (Szkoła Doktorska NCBJ)

Title: Dust attenuation in ALMA-detected Ultra Dusty Star-Forming galaxies up to z = 4

Abstract:

Despite its low contribution to the total mass of the interstellar medium (ISM), dust plays a crucial role in the evolution of galaxies, and it has the biggest impact on the shape of their total emission. The affluence of infrared and radio detections of millions of galaxies in the COSMOS field, provided by powerful instruments such as Herschel and ALMA, has allowed us to study the cold dust in galaxies and its variation over a wide range of redshift. A key element in reproducing the total spectral energy distribution of galaxies, is assuming a dust attenuation law which accounts for the behaviour and the imprints of dust in the ISM. However, different studies have shown that a single law cannot fully model dust in a large sample of galaxies. This non-universality of attenuation laws should be considered in order to accurately account for dust, and therefore in deriving the physical properties of galaxies. In this work, we study different attenuation laws in a statistical sample of ALMA-detected galaxies in the COSMOS field. We probe the resulting variation of key physical properties of these galaxies such as the star formation rate, the stellar mass and the dust to stellar mass ratio. We also investigate the dust temperatures in the ISM and spatial extent of the dust continuum and the implication that it might have on the attenuation curve. We find that a bouquet of attenuation curves must be used in order to reproduce the UV spectrum. Although these curves are not redshift-dependent, they are correlated to the relative spatial distribution to the stellar population of heavily dust-obscured galaxies, and we find a dependence of attenuation laws on the cold dust emission temperatures constrained by ALMA.

18 March 2021

Speaker: Francesco PISTIS (Szkoła Doktorska NCBJ)

Title: VIPERS: analysis of the FMR and its projections at z~0.7. Can observational biases affect their shapes?

Abstract:

Galaxy metallicity, a result of the integrated star formation history and evolution of the interstellar medium, is an
important property describing galaxy evolution. As such it has been widely studied in the local Universe with the data from the SDSS,
as well as its relations with galaxy stellar mass and SFR. The relation between these three galaxy physical properties, known as
Fundamental Metallicity Relation (FMR), was shown not to undergo any significant evolution at least up to z~2. In spite of that, different
studies find some differences in 2D projections of this relation. However, these studies are based on very different samples, with
different data selection at different redshift ranges. In our work we aim at finding FMR evolution from z~0.6 to z~0, making
use of the unprecedented statistics of the VIMOS Public Extragalactic Survey (VIPERS) and comparing it to the local SDSS sample. Having that
goal in mind, we study the effect of different selection biases introduced into the SDSS sample on both the FMR and its 2D
projections. We find significant differences occurring when different data selection, mimicking the selection of higher redshift samples, is
applied. Then, we compare these results with the data from the VIPERS sample at z~0.6. We conclude that both FMR and its projection at z~0.6
to z~0 are not in agreement even when the data selection effects are carefully applied. This implies a small but statistically significant
evolution of the FMR between z~0.6 to z~0 which needs to be taken into account in future studies.

11 March 2021

Speaker: Jaime de Cabo Martin (Szkoła Doktorska NCBJ)

Title: Exploring the primordial power spectrum of scalar perturbations from quantum bounce cosmologies.

Abstract:

Observational data from the Cosmic Microwave Background indicates that the Universe has emerged from its primordial phase in a very peculiar state: as a patch of flat, isotropic and homogeneous space furnished with small adiabatic density perturbations with nearly scale invariant amplitude spectrum. In this talk we will briefly review the main problems of the standard cosmological model for the description of the primordial universe and we will try to solve them not within the usual inflationary solution but in the framework of quantum bounce cosmology. We will present the basic ideas for performing such a description using Hamiltonian formulation of General Relativity. We will derive the reduced scalar quantum Hamiltonian for the flat FLRW universe filled with a perfect fluid. We will introduce the so-called Natural and Mukhanov parametrizations for the description of the dynamics of the scalar perturbations. Finally, we will investigate the primordial power spectrum of such perturbations, trying to approach the solution both numerically and analytically. 

4 March 2021

Speaker: Arantxa Tymowska (Szkoła Doktorska NCBJ)

Title: Quarks at NEik accuracy in the CGC: Forward quark-nucleus scattering

Abstract:

Within the theory of Color Glass Condensate we derived the Next-to-Eikonal corrections to the background quark propagator from relaxing two Eikonal conditions.  These two different corrections to the eikonal approximation combine together and provides a gauge covariant expression for the quark propagator at NEik accuracy. We then apply our results to quark (or antiquark) scattering on a nucleus at NEik accuracy, considering both unpolarized cross section and helicity asymmetry.

28 January 2021

Speaker: Ubaldo Cavazos (Studium Doktoranckie NCBJ)

Title: Unification via vector-like fermions

Abstract:

The pursuit for an ultimate theory of nature has been driving the particle physicists for decades. One
popular idea explored over the years is the unification of all the fundamental interactions into one
common description. In this talk, I will discuss extensions of the Standard Model in which the gauge
coupling unification is achieved by introducing new vector-like fermions and scalars with the masses in
the TeV range. I will show how the long-lived particles searches can be employed to derive the mass
limits for those exotic particles, and how those limits depend on the particle representation.

21 January 2021

Speaker: Gabriele Riccio (Studium Doktoranckie NCBJ)

Title: Getting ready for the LSST data – estimating the physical properties of main sequence galaxies.

Abstract: The upcoming Large Survey of Space and Time (LSST), conducted by Vera Rubin Observatory, will produce, over a 10-year period, multi-petabyte archive of images and catalogs of astrophysical sources on more than 18000 square degrees of the southern sky. Reaching magnitude depth of around 26.5 (AB) in the six bands ugrizy, LSST data will be useful to perform a wide variety of high precision statistical studies, allowing to obtain more accurate measurements of astrophysical quantities. I will present studies based on simulated LSST observations of real galaxies in the ELAIS-N1 and COSMOS fields of the Herschel Extragalactic Legacy Project (HELP) survey. Spectral Energy Distributions (SEDs) were fitted to the real and simulated photometric measurements of 65,889 galaxies in the redshift range 0 < z < 2.5, using the latest release of a galaxy SED fitting code CIGALE. We compare main galaxy physical parameters, such as star formation rate (SFR), stellar mass and dust luminosity obtained from real data using ultraviolet and infrared observations to the same parameters obtained from the simulated optical LSST measurements only. We conclude there is a possible overestimation of SFR, dust luminosity and dust mass if they are calculated with LSST photometric measurements only. This overestimation is found to depend on redshift, diminishing up to z = 2.5. The least sensitive parameter is the stellar mass which was found to be reliably estimated even if based only on the optical bands.

14 January 2021

Speaker: Kamil Skwarczyński (Studium Doktoranckie NCBJ)

Title: Constraining T2K oscillation fit using proton information from ND280

Abstract: Tokai to Kamioka (T2K) is a long baseline accelerator neutrino experiment. T2K uses the near detector (ND280) to constrain cross-section models as well as flux model. This allows to significantly reduce the systematic error of the Far Detector event rate prediction. T2K cross-section models describe various neutrino interactions like CCQE, 2p2h, DIS. Model constraints are obtained by fitting parametrized model to data (so called ND280 fit).

T2K is planning to expand ND280 fit by including proton information (so called proton samples). Proton samples showed improvement in constraints of many parameters describing the model. The crucial feature of proton samples is that they separate phase space of many key variables used in modeling of neutrino interactions. To fully utilize the new samples T2K is also expanding systematic uncertainty model, one of such new parameter is nucleon FSI.

7 January 2021

Speaker: Artem Poliszczuk (Studium Doktoranckie NCBJ)

Title: Active Galactic Nuclei Catalog from the AKARI NEP-Wide field

Abstract: I will present a new AGN catalog from the AKARI NEP-Wide field. Currently the standard method of Active Galactic Nuclei (AGN) selection in the data collected by the AKARI satellite is based on the near- and mid-infrared limits (Lee et al. 2007). This method allows to select AGN candidates with high efficiency at the expense of strong reduction of the catalog size. Our method is based on broad ensemble of supervised machine learning algorithms trained on spectroscopically confirmed sample. The AGN target selection for this sample was strongly influenced by the mid-IR selection. Our method shows high consistency with Lee et al. method, however it does not rely on mid-IR measurements, utilizing only near-IR AKARI passbands and new SUBARU/HSC optical data. New method gives more efficient way for AGN selection in optical and NIR data, being also an important preliminary study of  upcoming surveys synergies such as LSST and Euclid.


Further information on electromagnetic transition form factors can be acquired through the self-analyzing weak decay of the ground-state hyperon: computing the respective multi-differential four-body decay width results  in an additional term containing a relative phase between combinations of the original form factors.

17 December 2020

Speaker: Hareesh Thuruthipilly (Studium Doktoranckie NCBJ)

Title: Introduction to Emergent Gravity Paradigm and Emergence of Cosmic Space

Abstract:

On the backgrounds of connections between gravity and thermodynamics, the emergence of cosmic space as cosmic time progresses is an exciting idea advanced by Padmanabhan to explain the accelerated expansion of the universe. The generalisation of Padmanabhan’s conjecture to the non-flat universe has resulted in scepticism about the choice of volume such that the law of emergence can not be appropriately formulated if one uses proper invariant volume. The deep connection between the first law of thermodynamics and the law of emergence, motivate us to explore the status of  the first law in a non-at universe when one uses proper invariant volume. We have shown that the first law of thermodynamics, dE = TdS+WdV cannot be formulated properly for a non-flat universe using proper invariant volume. The failure in formulating the first law of thermodynamics with invariant volume hints to why our universe is spatially flat.

In this talk, I will give a brief introduction to the emergent gravity paradigm and its application in cosmology.

10 December 2020

Speaker: Nora Salone (Studium Doktoranckie NCBJ)

Title: Electromagnetic transition form factors and Dalitz decays of hyperons

Abstract: This project aims to gain information about the hyperon structure through the study of Dalitz decays of a hyperon resonance to a ground-state hyperon and an electron-positron pair. The usual framework of fixed target experiments, albeit very suitable for nucleons, is not as effective for hyperon resonances. One should consequently change the explored kinematical region, from space-like to time-like $q^2$, with the aid of crossing symmetry.

After parametrizing the corresponding baryon-photon-baryon vertex through the use of electromagnetic transition form factors, we formulate double differential decay rates for different spin-parity combinations of the initial state resonance ($J^P = \frac{1}{2}^\pm, \frac{3}{2}^\pm$) transitioning to a ground-state hyperon ($J^P = \frac{1}{2}^+$). Such decay rates are then computed at $q^2=0$ (“QED-type” approximation) and compared to the original quantities where a “radius” structure has been implemented through a low-energy approximation of the form factors. This parallelism can give a rough estimate for the measurement accuracy needed to distinguish between a structure-less and a composite hyperon, namely the minimum requirements for the hyperon internal structure to be “seen”.

Further information on electromagnetic transition form factors can be acquired through the self-analyzing weak decay of the ground-state hyperon: computing the respective multi-differential four-body decay width results  in an additional term containing a relative phase between combinations of the original form factors.

3 December 2020

Speaker: Yashwanth Prabhu (Studium Doktoranckie NCBJ)

Title: On the Determination of 𝛿CP with Accelerator Neutrinos

Abstract: One of the most important open questions in particle physics is whether the CP symmetry is violated in the leptonic sector- more specifically in the neutrino sector. It is well known the CP symmetry is violated in the quark sector. Discovery of CP violation in the neutrino sector will have implications on the observed matter and antimatter asymmetry in the Universe. The leptonic CP violation arises through the phase 𝛿CP which is a parameter in the neutrino mixing matrix. If 𝛿CP takes a non-conserving value, it will result in CP violation.

In my thesis, I studied the effect of 𝛿CP on neutrino and anti-neutrino oscillation probabilities and extended the same to the study of event rates at long baseline neutrino experiments. In this talk, I will discuss the results obtained from my analysis of accelerator neutrinos that travel 1,300 km before detection.

26 November 2020

Speaker: Michał Jędrzejczyk (Studium Doktoranckie NCBJ)

Title: Establishment of reasonable model to simulate emergency passive coolant system in HTTR reactor

Abstract: International Atomic Energy Agency (IAEA) Coordinated Research Program (CRP) on “Heat Transport and Afterheat Removal for Gas-cooled Reactors under Accident Conditions” started in November 1993. In this program, benchmark tasks were proposed for the analysis of passive afterheat removal from gas-cooled reactors (GCR) under accident conditions. The specific objective of the benchmark program is to capture the essential heat transfer features of reactor-to-reactor vessel cooling system (VCS) and provide useful information applicable to a wide variety of designs, operating conditions and model parameters.

In the present study, a 1/6 scale model of VCS for High-Temperature Test Reactor (HTTR) was used to develop a reasonably accurate thermal-hydraulics model of a passive cooling system. HTTR is a graphite-moderated gas-cooled research reactor in Oarai, Ibaraki, Japan, operated by the Japan Atomic Energy Agency (JAEA). The reasonable 2D model was established by using ANSYS Fluent software. In the study temperature profiles of the outside of the scaled reactor vessel for three experiment configurations were obtained numerically and compared with experimental results. The numerical results showed good agreement with the experimental ones. Moreover, a simplified numerical approach has been proposed and new heat transfer coefficients were determined. The approach allows for a two-fluid system simulation with significantly reduced computational costs.

19 November 2020

Speaker: Luis Eduardo Suelves (Studium Doktoranckie NCBJ)

Title: Anisotropic multiplicative bias in weak lensing shear estimates

Abstract: Gravitational weak lensing, the weak regime of gravitational lensing phenomena, arises in the sky as a slight shape distortion of observed galaxies, quantified as a change in their ellipticity. As the only information of a galaxy’s ellipticity that we have is in the observation itself, the gravitational effect has to be extracted statistically. Simply speaking, the intrinsic shape of a set of galaxies at an astronomical frame would stack to that of a circle, therefore, any deviation from this stacked shape would be produced by some mass distribution.

This Master Thesis project was dedicated to characterize the systematic effects that can bias the measurements in weak lensing and cosmic shear surveys of the shear, a main quantity to characterize weak lensing studies. We produced highly simplified simulations of astronomical frames, with a uniform shear applied to the galaxies, using the Stuff/SkyMaker package, and then applied the KSB shear estimation method. The formalism used to calibrate the measurement systematics, called calibration bias, differs from the one found usually in the literature by the introduction of extra cross-components.

12 November 2020

Speaker: Mateusz Kmieć (Studium Doktoranckie NCBJ)

Title: Feasibility Studies of CPT Violation Measurement in Flavour Oscillations of the Neutral D Meson

Abstract: Mesons are bound quark-antiquark pairs. Flavoured neutral mesons are defined as mesons with no electric charge and non-zero strangeness, charm or beauty content. The weak interactions mix neutral-mesons with their antiparticles
leading to spontaneous transitions between meson and  antimeson  quantum  states, which  can  serve  as  a  sensitive  interferometer  facilitating precision testing of CPT invariance.

The main objective of my master’s thesis was to perform feasibility studies of the CPT violation (CPTV) measurement in the system of the neutral D meson. CPT symmetry is one of the fundamental symmetries of the Standard Model (SM). The measurement of CPTV would mean that there exists physics beyond the SM. My goal was to probe the level of sensitivity of testing CPTV in the system of the neutral D meson. For this purpose, I created a Monte Carlo (MC) generator of neutral meson decays, where CPTV was controlled by a complex phenomenological parameter z. The MC generator was used to simulate the CPT violation effect at the level of z=0.1 for an ensemble of 100 pseudo-experiments. Each experiment consisted of N=6.5*107 of MC generated events corresponding to the number of D0 -> K+pi decays collected by the LHCb (2011-2012). For such statistics, the CPT violation effect would be seen at seven standard deviations level. This can be contrasted with the best experimental limit for the parameter z of order O(1) provided by the FOCUS collaboration.

5 November 2020

Speaker: Victor Martínez-Fernández (Studium Doktoranckie NCBJ)

Title: CP violation in the Minimal Linear sigma Model

Abstract: In this seminar we review the generalities of composite Higgs (CH) models that aim to solve the Standard Model hierarchy problem with the introduction of the Higgs as a Nambu-Goldstone boson as well as a new strong sector with new heavy particles. In particular we work with a renormalizable CH model, the Minimal Linear sigma model (MLsM). The phenomenology of this model is extended with the study of the electron electric dipole moment (eEDM) in accordance with the experimental constraints furnished by the ACME Collaboration in order to set limits on the MLsM CP-violating phases.

Our interest in the eEDM stems from the fact that a non-zero value implies CP violation. Since it is a low-energy observable, we perform an integration-out of the heavy fields, obtaining an effective field theory that at 2 loop describes an eEDM (Barr-Zee diagram).

29 October 2020

Speaker: Maitrayee Mandal (Studium Doktoranckie NCBJ)  

Title: Improving the Tau Appearance Study in Atmospheric Neutrinos with Neutron Capture Information at the Super-Kamiokande Experiment

Abstract: The Super-Kamiokande (SK) experiment is dedicated to the detection and understanding of neutrino physics. Currently, few experiments constrain the tau neutrino sector and therefore, improving the detection of the appearance of tau neutrinos in atmospheric neutrino flux at SK is an interesting problem. To identify the tau signal from the background, a neural network is utilised at SK. The predominant background consists of neutral current interactions of neutrinos of all flavors. Lesser neutron captures per event are expected in case of the tau signal than in the predominant background, however the present neural network does not include an input of neutron capture information. The recent SK-Gd upgrade will result in 90% of the neutrons produced in the detector being detected and recognised. In the presented study, we show that adding a new input corresponding to the number of neutron captures per event allows for better classification of the tau-signal. We also observe a positive correlation of initial kinetic energy of the event with the separation of signal and background due to neutron captures.

22 October 2020

Speaker: Paritosh Verma (Studium Doktoranckie NCBJ)  

Title: Searching for gravitational waves from pulsars in Jordan Brans Dicke theory

Abstract: I shall talk about gravitational waves in Jordan Brans Dicke (JBD) theory. There are two tensor polarization states in the General theory of relativity (GR) but there can also be vector and scalar polarization states in alternative theories of gravity. The JBD theory is one of the attempts to modify the general theory of relativity by varying gravitational constant G and it has three polarization states. The first two states are the same as in GR and the third one is the scalar polarization. We have extracted these three polarizations for a particular case of a rotating neutron star with a mountain and then calculated the F-statistic. Finally, we have developed a simulation to estimate the amplitudes from quadrupole as well as dipole emission.