Physics Seminars

Seminars in 2022/23

Upcoming Speakers

Seminars before 2022/23

12 May 2022

Speaker: Anatolii Koval (Studium Doktoranckie 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.

5 May 2022

Speaker: Krzysztof Jodłowski (Studium Doktoranckie NCBJ)

Title: Indirect detection of long-lived particles in a less-simplified dark Higgs portal

Abstract:

Simplified models of light new physics are an important theoretical and experimental benchmark. Models that extend minimal scenarios by introducing other degrees of freedom are well motivated ways to go beyond the Standard Model (SM). In this talk, I will focus on the light dark Higgs portal that connects the dark sector consisting of, e.g., TeV-scale secluded dark matter (DM) with the SM. I will illustrate the phenomenology of this model, focusing on the signatures of DM and long-lived particles (LLP) in complementary experimental searches. These include i) the intensity frontier searches for light new physics, ii) indirect detection (ID) of secluded WIMPs, and iii) future CMB radiation surveys. Finally, I will highlight the important role of non-local effects present in the ID of LLPs which significantly affects the detection strategies, usually tailored to WIMPs. These effects include a) an additional contribution to the photon flux due to the “GC diffusion” effect, b) a linear flux decrease in the long-lived regime due to finite DM density support, and c) a faster flux decrease with LLP decay length for observations focused on small regions of interest, compared to large ones.

28 April 2022

Speaker: Michał Mazurek (Szkoła Doktorska NCBJ)

Title: Fast simulation interface and custom datasets in Gaussino

Abstract:

Monte Carlo simulations are key to the design and commissioning of new detectors as well as the interpretation of physics measurements. A new version of the LHCb Gauss simulation framework has been developed to better accommodate new simulation techniques and software technologies to produce the necessary samples required for the Run 3 physics program of the LHCb experiment. It provides the LHCb-specific functionality while the generic simulation infrastructure has been encapsulated in an experiment-independent framework, Gaussino. In this talk, I am going to present the fast simulation interface, the latest feature in Gaussino developed to interact with Geant4 to replace its detailed description of physics processes with fast simulation models. I will also present how the built-in mechanism that handles an additional geometry at configuration time can be used to produce custom datasets and, in particular, training and validation datasets for fast simulation models.

21 April 2022

Speaker: Grzegorz Żarnecki (Studium doktoranckie NCBJ)

Title: Cross section measurement of the charged current muon antineutrino single π- production at T2K

Abstract:

T2K experiment is a long baseline neutrino oscillation experiment in Japan. Cross section measurements of (anti)neutrino interactions in sub-GeV to few GeV energy range allow to constrain the systematic uncertainties in the oscillation analysis. Single charged pion production is a relevant interaction mode at this energy scale. The biggest contribution to that mode is due to the baryonic resonance interaction, coherent interaction and deep inelastic scattering.

In this seminar I will present the cross section measurement of single π- production in muon antineutrino CC interaction on hydrocarbon. The cross section is reported as double-differential in muon kinematical variables i.e. momentum and cosine of the muon emission polar angle.

7 April 2022

Speaker: Mahmoud Hamed (Szkoła Doktorska NCBJ)

Title: Reverse-engineering galaxy spectra to decode the IRX-β relation at intermediate redshift

Abstract:

n galaxies, different components interact with each other on various timescales. An example of such interaction is the interplay between young and as well evolved stars with dust. This complex interplay influences the total spectra of galaxies. Dust affects the shape of the spectral energy distribution (SED) like no other component, despite its low  contribution  to  the  overall mass  of the  baryonic  matter.  At  higher  redshifts,  the  challenging  measurements  of  FIR emission  are  overpowered  by  the  easily  available  rest-frame UV  emission. This in turn limits the wavelength range from which the physical properties are inferred, therefore, a correct understanding  of physical processes  that prevail at short wavelength domain,  like  dust attenuation,  becomes  critical. Observationally, many galaxies seem to follow what is known as the IRX-β relation, which links heavily-attenuated UV spectral slope (β) and the IR excess of galaxies characterised by the ratio between the IR (mainly dust)  and UV (mostly composed of young stars) luminosities (L(FIR)/L(UV)). However, this relation is not universal, and outliers for it are often encountered. Understanding such relation and its connection to dust attenuation properties will help us uncover and understand the role of dust, and its attenuation at higher redshifts.

Our study used a unique dataset from the “VIMOS Public Extragalactic Redshift Survey” (VIPERS), which mapped in detail 24 deg2 of the sky sampling galaxies at redshift~0.7.    We use the robust Oii, Oiii, and Hβ line detections of our statistical sample from VIPERS to estimate the gas-phase metallicities at the redshift range 0.5<z<0.9. We derive key physical properties that are necessary to study galaxy evolution, such as the stellar masses and the star formation rates, from the SED fitting tool CIGALE. We find a strong dependence of the IRX-β relation on gas-phase metallicity in our sample and dependencies on stellar properties of galaxies like stellar ages, stellar masses, and specific star formation rates. We have also checked morphological parameters, and we find that  the compactness of our sources characterised by the Sérsic indexes is also sensitive to the location on the IRX-β  plane.

31 March 2022

Speaker: Francesco PISTIS (Szkoła Doktorska NCBJ)

Title: The FMR up to z~0.7: investigating different methods

Abstract:

The studies of galaxy metallicity — as the outcome of the integrated star formation history and the evolution of the interstellar medium — can constrain the description of galaxy evolution. This subject has been widely studied in the local Universe, in particular using data from the Sloan Digital Sky Survey (SDSS). In this project, we develop such studies up to redshift z~0.7 with the data from VIMOS Public  Extragalactic Redshift Survey (VIPERS) and quantify its possible evolution with high statistical precision. We test different methods to study the Fundamental Metallicity Relation (FMR) and compare samples to review if they can lead to the same conclusions on the metallicity evolution between different samples, showing the pros/cons of each method and analogies/dissimilarities between them. We built two control samples by cross-matching all SDSS galaxies on physical properties (stellar mass and star formation rate) and galaxy type. We compare three different methods: i) the different projections of the FMR, ii) a non-parametric method, and iii) an “evolutionary” method. The biggest result of the control sample on physical properties is to show the same projection of the data at z~0.7 in the metallicity vs SFR plane. Both the direct difference in metallicity — in each stellar mass-SFR bin between the local and intermediate redshift sample — and the non-parametric method show an increasing difference with increasing stellar mass, while the “evolutionary’’ method shows the samples diverging at lower stellar masses.

24 March 2022

Speaker: Jaime de Cabo Martin (Szkoła Doktorska NCBJ)

Title: Inequivalent Quantum Cosmological bouncing models and the primordial structure

Abstract:

By quantising the background as well as the perturbations in a simple one fluid cosmological model, we show that there exists an ambiguity in the choice of relevant variables, potentially leading to incompatible observational physical predictions. In a classical inflationary background, the exact same canonical transformations lead to unique predictions, so the ambiguity we put forward demands a semiclassical background with a sufficiently strong departure from classical evolution. The latter condition is clearly satisfied by bouncing models. We propose coherent states as the tool for introducing the semiclassical universe. We solve the quantum dynamics of the perturbation modes both analytically and numerically and investigate the amplitude spectra of the perturbations. We study the underlying quantum state, the Bunch-Davies vacuum, from the point of view of late-time observers by means of the Bogolyubov transformations. In particular, we study the phase space probability distributions obtained with the standard coherent states built from instantaneous vacua. We discuss the issue of the temporal phase shift with which the modes emerge from the bounce as sine waves. Finally, we find that the model may be fitted to data and shed light on the physical universe, constraining free parameters of the bouncing universe.

17 March 2022

Speaker: Arantxa Tymowska (Szkoła Doktorska NCBJ)

Title: DIS dijet production beyond eikonal accuracy

Abstract:

We derive subeikonal corrections to the quark propagator assuming that the quark is propagating through the whole medium in order to study DIS dijet production. We take into account NEik (Next-to-Eikonal) corrections from previous results for splitting before the medium and we calculate a new contribution coming from splitting inside the medium at NEik. This time we include not only corrections that contribute to Next-to-Eikonal accuracy that are due to considering a finite longitudinal width target and the interaction of the quark with the transverse component of the background field, here we also include the dynamics of the target. We then apply these corrections to the DIS dijet cross section for both inclusive and diffractive production.

10 March 2022

Speaker: Gabriele Riccio (Szkoła Doktorska NCBJ)

Title: Star formation rate measurement in astrophysics

Abstract:

Star formation is one of the main mechanisms of energy production in the universe and one of the key processes that are linked to the evolution of galaxies. Over the past two decades we have witnessed an explosion of data from local and distant galaxies across the entire electromagnetic spectrum. These observations gave us an unprecedented picture of the star-forming activity in galaxies, the parameters it depends on (e.g. gas content, physical conditions in the interstellar medium, dynamical state of galaxies), and its evolution over cosmic time. The common denominator in all these studies is the use of diverse techniques for quantifying the recent star-forming activity in the different environments.  The purpose of this talk is to provide an introduction of the methods used to measure the intensity of star-forming activity in galaxies (their star-formation rates), focusing on spectral energy distribution (SED) fitting methods and star formation rate evaluation from the galaxy X-ray emission. In this context, I will discuss my PhD project, dividing it into two parts: 1) how the upcoming Legacy Survey of Space and Time (LSST) data from the Vera C. Rubin Observatory can be employed, using SED fitting methods, to constrain the physical properties of normal star-forming galaxies (main-sequence galaxies); 2) Modeling of the X-ray emission and probing of X-ray luminosity versus star formation rate relation in galaxies.

3 March 2022

Speaker: Kamil Skwarczyński (Szkoła Doktorska NCBJ)

Title: T2K Near Detector Fit

Abstract:

T2K (Tokai to Kamioka) is a long-baseline neutrino oscillation experiment located in Japan. One of the most challenging tasks of T2K is to study whether CP is violated in the lepton sector, which is suggested by recent T2K results. By utilizing the near detector (ND280) data, T2K can constrain neutrino interaction and flux uncertainties by fitting a parameterized model to data. This allows for a significant reduction of the systematic uncertainties in neutrino oscillation analyses.  One of two fitters responsible for ND fit uses Bayesian Markov Chain Monte Carlo (MCMC) method. New T2K ND fit introduces many improvements, including new samples with proton and photon tag. Talk will present preliminary T2K results and method used including posteriori predictive distribution etc.

27 January 2022

Speaker: Artem Poliszczuk (Studium Doktoranckie NCBJ)

Title: Introduction to Reverberation Mapping of Active Galactic Nuclei

Abstract:

During my presentation I will describe main concepts, observational results and open questions of Active Galactic Nuclei (AGN) reverberation mapping. Angular size of vast majority of active galaxy centers is way to small to be spatially resolved by modern instruments and thus cannot be directly observed via traditional methods. The reverberation mapping method allows to use variability properties of AGN to swap spatial resolution to time resolution and directly test vicinity of supermassive black holes in the centers of galaxies. Rapid development of  reverberation mapping studies in the past two decades makes it a very promising tool for galaxy evolution and observational cosmology.

20 January 2022

Speaker: Hareesh Thuruthipilly (Szkoła Doktorska NCBJ)

Title: Self-attention based encoder models for strong lens detection

Abstract:

The upcoming large scale surveys are expected to find approximately 10^5 strong gravitational systems by analysing data of many orders of magnitude larger than the current era. In this scenario,  non-automated techniques will be highly challenging and time-consuming. We propose a new automated architecture based on self-attention, which can substitute the currently used CNNs to find strong gravitational lenses. The advantages of self-attention-based encoder models over convolution neural networks are investigated and encoder models are analysed to optimise performance using the data from the Bologna Lens Challenge. From our study, we pointed out that self-Attention-based models have a clear advantage compared to simpler CNNs. A low computational cost and complexity make it a highly competing architecture to currently used CNN architecture. Moreover, introducing the encoder layers can also tackle the over-fitting problem present in the CNN’s by acting as effective filters and providing better stability for the network.

13 January 2022

Speaker: Nora Salone (Szkoła Doktorska NCBJ)

Title: The physics case for the CP-violation tests in hyperon decays at SCTF far detector

Abstract:

The observed matter-antimatter asymmetry in our universe can be explained theorizing the violation of the combined charge-conjugation–parity symmetry (CP), of which non-leptonic two-body weak decays of baryons are an important probe. We explain how and why the decays of strange baryons provide complementary information to the decays of kaons. We present a model-independent paramerization of the non-leptonic decays of the Λ- and Ξ-baryons produced at the at the next generation electron–positron J/ψ factories with luminosity of 10^35 cm^−2 s^−1. Using analytic approximations and numerical calculations we study the quantitative impact of spin
correlations and polarization in CP tests built from the produced, spin-entangled hyperon-antihyperon pairs.

We show that by using a longitudinally-polarized electron beam the statistical precision of the CP tests can be significantly improved. Furthermore, we map out further directions for possible improvements, like analysis of incompletely reconstructed events or a combination of the isospin related processes. Altogether these methods are promising for the observation of a statistically significant CP-violation signal with a strength corresponding to the standard model predictions. Finally, our results call for an update of the theory predictions with increased precision.

16 December 2021

Speaker: Yashwanth Prabhu (Szkoła Doktorska NCBJ)

Title: Development of a multiring electron neutrino sample at the T2K far detector

Abstract:

The Tokai to Kamioka (T2K) experiment is a long-baseline accelerator neutrino experiment that measures electron neutrino appearance and muon neutrino disappearance from a muon neutrino beam by observing neutrino events at the near and far detectors. T2K uses the Super Kamiokande (SK) as the far detector, which is a 50-kilo ton water-Cherenkov detector that observes Cherenkov rings from charged particles produced in neutrino interactions with water.

In the present oscillation analyses, T2K uses only single-ring electron neutrino events detected at SK. These single-ring events are dominated by charged current quasielastic interactions. Charged-current single pion events form the second most dominant signal events in electron neutrino appearance studies. In this mode, there can be two rings coming from electron and charged pion if the latter has a momentum above the Cherenkov threshold. The sample with no ring from the charged pion is already included in the oscillation analysis.

My study is aimed at developing selection cuts for including the sample with two Cherenkov rings. Being the second most dominant signal event, its inclusion in the samples can increase the statistics of electron neutrino events at SK and possibly improve sensitivity to the CP violation phase.

9 December 2021

Speaker: Michał Jędrzejczyk (Szkoła Doktorska NCBJ)

Title: Applying Approximate Bayesian Computation to reduce nuclear data uncertainties

Abstract:

The multiplication factor (keff) is a key parameter describing the dynamics of nuclear reactors. The uncertainty in its calculated value usually amounts to 1-2 %, measured in one relative standard deviation. It mostly originates from the imprecision with which neutron cross sections are known. 1 % in keff uncertainty is a lot. Reduction of this value would open a possibility to create more optimal nuclear reactor designs. There is a large database of well documented criticality benchmark experiments with precisely measured keff. It is called “International Handbook of Evaluated Criticality Safety Benchmark Experiments” and it is maintained by Nuclear Energy Agency. The goal of my research is to use the results of these experiments to decrease the uncertainties of neutron cross sections. In order to do that I will use a statistical tool called Approximate Bayesian Computation (ABC) and a criticality simulation software SCALE.

In this seminar, I will discuss neutron cross section uncertainties and other nuclear data deficiencies. I will give an introduction to ABC and present a simple example of how it can be used to reduce uncertainties of any mathematical model parameters. I will then show how I am going to apply it to reduce neutron cross sections’ uncertainties (which are parameters in keff calculations). Finally, I will discuss to what extent we can reduce calculated keff uncertainties this way.

2 December 2021

Speaker: Luis Eduardo Suelves (Szkoła Doktorska NCBJ)

Title: Photometry-based merger identification through Neural Network.

Abstract:

The evolution and dynamics of the galactic population are key elements for modeling the Universe history and structure. Within the Cold Dark Matter model, the gravitational pull between galaxies can lead to mergers: hierarchical growth interactions in which one galaxy “collides” with another, combining their stellar population, interstellar dust, and dark matter halos. This is likely to enhance the stellar formation in the daughter galaxy, influence its evolutionary history and modify strongly the shape of the original galaxies during the process.

Identifying galaxy mergers (and galaxy morphologies in general) is a very elementary modern astronomy problem, and it is crucial to understand these phenomena, their time scale, and their implications. I will present the projects I have been working on during my PhD. I have been working on galaxy mergers classification by means of Machine Learning methods, using real astronomical images (Pearson, Suelves at al. 2021, submitted to A&A) and photometric measurements (Suelves et al. 2021, in preparation)

25 November 2021

Speaker: Mateusz Kmieć (Szkoła Doktorska NCBJ)

Title: Practical Experimental Sensitivity for New Physics Discovery in LHC

Abstract:

Before announcing a discovery in particle physics we need to answer two fundamental questions. Firstly, we should ask ourselves what is the goodness of fit of our result to the tested theory (e.g. the Standard Model). Secondly, we need to check how well our measurement is described by the alternate theory (e.g. Beyond the Standard Model). In other words, we need to establish if our measurement is congruent with the chosen model and find the experimental sensitivity to discovery in the process of hypothesis testing. The sensitivity of an experiment is usually reported as the expected significance. It is typically obtained for a series of hypothesis tests on an ensemble of simulated data.

In my current research work, I am trying to establish the sensitivity of high luminosity experiments such as LHCb to CPT violation (CPTV) measurement with neutral meson oscillations. In this seminar, I will present methods for finding the expected significance with which one would be able to reject different values of CPTV parameter. I will present both the approach employing the Monte Carlo (MC) simulations (computationally expensive) as well as approximate methods allowing us to obtain the expected significance without the need of performing weary MC simulations.

18 November 2021

Speaker: Victor Martínez-Fernández (Szkoła Doktorska NCBJ)

Title: Inclusive and exclusive inelastic processes in QCD

Abstract:

For a long time, it was believed that fundamental constituents of atoms were electrons and nucleons until experiments conducted in the 1960s at Standford Linear Accelerator Center (SLAC) proved the existence of internal dynamics in the nucleons. With QCD as the fundamental theory for hadrons, we can describe hadronic structure via correlations between some degrees of freedom that we call quarks and gluons, collectively partons. The non-elementary nature of hadrons makes these correlators perturbatively unsolvable so we can only measure or model them. In this seminar, I review and compare 2 of these correlators/distributions, namely PDF and GPD, and discuss how to study phenomenology of a particular exclusive inelastic process (double deeply virtual Compton scattering) in order to extract information on the partonic distributions beyond leading-order accuracy.

4 November 2021

Speaker: Maitrayee Mandal (Szkoła Doktorska)

Title: Detection of Tau Neutrinos at the Super-Kamiokande Experiment

Abstract:

The Super-Kamiokande experiment (SK) is the famed water Cherenkov detector which discovered the oscillation of atmospheric neutrinos. As a result of the oscillation of atmospheric muon neutrinos, tau neutrinos are expected to appear. Therefore, direct detection of tau neutrinos in the flux of atmospheric neutrinos provides unambiguous confirmation of the phenomenon of neutrino oscillation. In 2018, SK excluded the hypothesis of no tau appearance with a significance level of 4.6��.

SK used machine learning techniques of neural networks (NNs) to classify the tau charged-current interactions from the interactions of the atmospheric muon and electron neutrinos. My research involves upgrading the NN for better classification. In particular, the signatures to classify these interactions are expected to be seen in neutrons, which are copiously produced in the particle showers arising from the tau and atmospheric neutrino interactions. So far, information related to neutrons has not been used at SK for discerning tau neutrinos.

The prospect of expanding the NN with new inputs pertaining to neutron captures is under consideration, owing to the enhanced detection of neutrons with the recent addition of gadolinium in SK. Preliminary results show that this additional information shall improve the NN classification, and hence, the detection of tau neutrinos.

28 October 2021

Speaker: Paritosh Verma (Studium Doktoranckie NCBJ)

Title: Probing GWs from pulsars in Brans-Dicke theory

Abstract:

A coupling constant determines how much force will be exerted in a given interaction. In renormalized I shall discuss the results of our recent paper on gravitational waves (GWs) from spinning neutron stars in Brans-Dicke (BD) theory. The BD theory attempts to modify the GR by varying gravitational constant G, and it has three polarization states. The first two states are the same as in GR, and the third is scalar polarization. We derive the response of a laser interferometric detector to the GW signal from a spinning neutron star in BD theory. We obtain a statistic based on the maximum likelihood principle to identify the signal in BD theory in the detector’s noise. This statistic generalizes the well known F-statistic used in the case of GR. We perform Monte Carlo simulations in Gaussian noise to test the detectability of the signal and the accuracy of estimation of its parameters. Finally, I shall present the total power radiated away in this theory and analytical formula to obtain the maximum limit of dipole amplitude.

21 October 2021

Speaker: Souvik Mondal (Szkoła Doktorska)

Title: Vector Like extension of Standard Model

Abstract:

A coupling constant determines how much force will be exerted in a given interaction. In renormalized perturbation theory, a coupling receives contributions from higher-order loop diagrams. Therefore, one can define the effective coupling as the sum of tree-level coupling and all higher-order contributions. The goal of the project is to find the Zff effective coupling. At the tree level this coupling is determined by the electroweak gauge coupling and the quantum numbers of the fermion. The loop corrections in the Standard Model are known and consistent with the experimental measurements. That is not the case for a generic BSM scenario, where the contributions to the effective coupling need to be calculated and confronted with the data. In my talk, I will discuss contributions to Zff effective coupling in a class of BSM scenarios considering vector-like fermions. I will also show how these results could be used to indirectly look for the New Physics.

14 October 2021

Speaker: Patrycja Dyrcz (Studium Doktoranckie NCBJ)

Title: Radiological characterization of metallic waste from particle accelerators for disposal after melting 

Abstract:

The operation of high-energy particle accelerators like the ones at the European Organization for Nuclear Research (CERN) leads to the unavoidable production of radioactive materials. Activated materials that cannot be reused or recycled need to be disposed of in dedicated disposal facilities for radioactive waste. In this presentation, I describe a novel radiological characterization method of low and intermediate level (LL and IL) metallic waste produced at CERN, which will be melted into ingots at an external facility prior to disposal.


I will give an overview of the main challenges and technical solutions associated with the radiological characterization at CERN: in-situ gamma spectrometry of massive items with multiple counting and dose-rate levels above 100 uSv/h at contact, modeling of activity concentrations in the spectrometry analyses, validation of scaling factors for LL and IL waste based on the analytical calculations and Monte Carlo simulations, and self-attenuation in waste packages. In addition, I will identify operational activity limits which take into account the acceptance criteria of the melting facility and of the final repositories, as well as the uncertainties associated with the characterization methodology.

10 June 2021

Speaker: Szymon Nakoneczny (Studium Doktoranckie NCBJ)

Title: Large Scale Structure and Cosmic Microwave Background in study of the Universe

Abstract:

Astrophysicists are now facing some of the biggest mysteries in science. Dark Matter (DM), which interacts only gravitationally and makes up to about 27% of the Universe, and Dark Energy (DE), which accelerates expansion of the Universe and makes up to about 68% of it, both fit to the theoretical model, but we do not understand their nature. On the other hand, we measure different values of cosmic parameters from different probes, which creates cosmic tension not explainable by any known theory. In my talk, I will describe how observations of the Large Scale Structure (LSS) and Cosmic Microwave Background (CMB) are used to shed light on these unknown problems. I will explain the concept of the epoch of recombination, in which the CMB originates, and give an introduction to the theory of the gravitational collapse which led to the development of the LSS. Then, I will give an introduction to Integrated Sachs-Wolfe (ISW) effect which changes energy of CMB photons as they travel through the decisively expanding Universe. In terms of data, I will focus on one of the largest radio surveys to date, the International Low-Frequency Array (LOFAR), which operates in many countries across Europe, including Poland. Finally, I will show my initial results on cosmic inference using LOFAR and CMB data.

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

3 December 2020

26 November 2020

19 November 2020

12 November 2020

5 November 2020

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.