High Energy Physics Seminar
2006/2007 | 2007/2008 | 2008/2009 | 2009/2010 | 2010/2011 | 2011/2012 | 2012/2013 | 2013/2014 | 2014/2015 | 2015/2016 | 2016/2017 | 2017/2018 | 2018/2019 | 2019/2020 | 2020/2021 | 2021/2022 | 2022/2023 | 2023/2024 | 2024/2025
2023-06-16 (Friday)
room B2.38, Pasteura 5 at 10:15 
dr Pragati Mitra (IFD UW)Analysing Ultra High Energy Cosmic Ray Air Showers with GRANDProto300
Detecting Ultra High Energy Cosmic Rays (UHECR) and Neutrinos through radio detection is a mature technique that offers a promising avenue for highly inclined air showers. The GRANDProto300 (GP300) array is a pathfinder for the Giant Radio Array for Neutrino Detection (GRAND) project, which will be deployed at a remote mountain site in the Gobi desert, China. Serving as a test bench, the GP300 array is expected to pioneer techniques of autonomous radio detection including identification and reconstruction of nearly horizontal cosmic-ray air showers and shed light on understanding the 'transition region' from the galactic to extragalactic cosmic-ray sources. In this seminar, we will explore the prospects of studying air shower parameters with radio technique, then look into the ongoing analysis efforts including offline signal identification and shower reconstruction.
2023-06-02 (Friday)
room B2.38, Pasteura 5 at 10:15
dr hab. Katarzyna Grzelak (IFD UW)Tau neutrinos. What do we know? What can we learn from them?
Tau neutrinos are the least studied leptons. Due to difficulty in distinguishing tau neutrinos from other neutrino flavours, low cross-section and high threshold energy for charged-current interactions only 19 tau neutrino candidates have been event-by-event selected to date.In the seminar the current status of tau neutrino-related physics, new experiments and new ideas to improve our knowledge of lepton sector will be presented.
2023-05-26 (Friday)
room B2.38, Pasteura 5 at 10:15
prof. dr hab. Tomasz Bulik (OA UW)Gravitational wave astrophysics at the beginning of O4
The O4 observational run is starting now. I will review the current detections and their significance for astronomy and fundamental physics. As the bulk of detections are binary black holes I will describe the currently considered models of their formation and compare the predictions of these models with the data. Finally I will talk about hopes for the O4 run.
2023-05-19 (Friday)
room B2.38, Pasteura 5 at 10:15
Lech Wiktor Piotrowski (IFD UW)Towards identifying the sources of Ultra-High Energy Cosmic Rays with the GRAND experiment
Even though the first UHECR was detected almost 60 years ago, the origin of these particles remains a mystery. For lower energies, their paths are twisted by the Galactic magnetic field, while for higher energies their fluxes are extremely low. That makes identifying the sources unreachable even for the largest existing observatories, that occupy hundreds to thousands of square kilometres.The problem of the low flux can be solved with building observatories that observe orders of magnitude larger volume of the atmosphere than the current ones. In addition, looking not directly at UHECR, but at neutrinos generated by them close to the source, can eliminate the influence of cosmic magnetic fields. These two ideas will be incorporated into the Giant Radio Array for Neutrino Detection (GRAND) - a future experiment to detect Earth-skimming neutrinos with huge arrays of cheap radio antennas.The contents of the seminar will include the idea behind the radio detection of UHE CRs and neutrinos, current status of GRAND prototypes, the role of the Polish group and the experimental challenges that we are facing.
2023-04-28 (Friday)
join us at 10:15
dr Magdalena Posiadała-Zezula (IFD UW)Study of neutrino mass ordering with the atmospheric neutrinos at Super-Kamiokande
Super-Kamiokande (Super-K) is the world's largest underground water Cherenkov detector which has been studying the atmospheric neutrino oscillations since 1996. Atmospheric neutrinos are famous for covering a wide energy range, have both neutrinos and antineutrinos, with electron and muon flavours, which oscillate to tau neutrinos and are sensitive for matter effects in the earth. Analysis of the atmospheric neutrino data from all five run periods of Super-K running with ultra-pure water, years 1996 - 2020, will be presented. The fiducial volume region has been expanded from 22,5 kton to 27,2 kton, which allowed us to use also the events with reconstructed vertex at least 1~m from the nearest wall of the detector. Additional studies have been performed by adding information from T2K published binned data muon neutrino disappearance and electron appearance. Over the range of parameters allowed at 90% confidence level, the normal mass ordering for neutrinos is favoured based on the combined results from Super-K and with T2K results.
2023-04-21 (Friday)
room B2.38, Pasteura 5 at 10:15
dr Alibordi Muhammad (IFD UW)Strange phase in beautiful oscillation: Measurement of weak phase in the neutral bottom meson decay
The smallest deviation from the precise value of the CP-violating weak phase predicted by Standard Model in the B_s to Jpsiphi decay mode would hint for a new domain of physics. Also improving precision with higher statistics of the Run-II proton-proton collision data collected by CMS detector may help to constrain the future theories. These were the motivations of measuring the weak phase in the B_s to Jpsiphi decay. In this talk we will see how the weak phase measurement is done with ~97fb^-1 of the 13TeV proton-proton collision data and what level of precision is achieved.
2023-03-31 (Friday)
room B2.38, Pasteura 5 at 10:15
dr hab. Artur Ukleja, prof. AGH, mgr Jakub Ryżka (NCBJ, AGH)Measurements of CP-violating asymmetries in charm decays in the charmingly-beauty experiment - LHCb
One the main goal of High Energy Physics is a search for physics beyond the Standard Model (called new physics). The measurements of CP-violating asymmetries in particle decays containing a charm quark create perfect environment for the new physics searches since the background from the Standard Model is small as the expected value of CP violation is about a few per milles or less. It is significantly smaller then observed in beauty sector. The LHCb experiment tests the Standard Model predictions in very precise measurements of CP violation using very sophisticated research methods. For example, finding disagreement between measured and predicted values will be indirect indication of the existence of new physics. So far, in the charm sector, CP violation is confirmed as a nonzero difference between two CP-violating asymmetries in D^0 to K^- K^+ and D^0 to pi^- pi^+ decays. This result obtained in 2019 only raised the question of whether the observed difference reflects the CP violation in the D0 meson decays into a pair of kaons, into a pair of pions, or both. Possible interpretations will be discussed during the seminar. Recently, the LHCb experiment has measured the direct CP asymmetries separately for the two decay modes: D^0 to K^- K^+ and D^0 to pi^- pi^+. These results will be presented during the seminar as them constitute the first evidence for CP violation in a specific charm hadron decay. The compatibility with the hypothesis of CP symmetry is 3.8 standard deviations. The new searches for CP asymmetries in three-body charm baryon decays will be also presented. Three-body processes are always more rare than the two-body processes, but they can provide much more information about CP violation. Many observables are available to measure in multi-body processes. In contrast, in two-body processes, only one variable is measured (global result of CP violation). So far, in charm baryons the level of 2.7 standard deviations of agreement with CP symmetry was measured. The new approaches will be discussed during seminar as well as their tests obtaining in control decays.
2023-03-24 (Friday)
room B2.38, Pasteura 5 at 10:15
dr Marek Walczak (AstroCent CAMK)Searching for dark matter with liquid-argon detectors
The nature of dark matter remains unknown and its origin is currently one of the most important questions in physics. In particular direct searches for WIMP dark matter particle interactions with ordinary matter are carried out with large detectors located in underground laboratories to suppress the background of cosmic rays. One of the currently most promising detection technologies is based on the use of a large mass of liquid argon or xenon as a target in the detector.In this talk, I will discuss the status and plans for dark matter searches with detectors based on liquid argon. I will present the currently operating DEAP-3600 experiment (at SNOLAB, Canada) and introduce the DarkSide-20k detector (under construction at the Gran Sasso laboratory, Italy) and in particular the design of its neutron veto.
2023-03-17 (Friday)
room B2.38, Pasteura 5 at 10:15
prof. Maurizio Consoli (INFN, Sezione di Catania, Italy)Theoretical motivations and experimental signals for a second resonance of the Higgs field
Theoretical arguments and lattice simulations suggest that, beside the known resonance of mass m_h= 125 GeV, defined by its quadratic shape, the effective potential of the Higgs field could exhibit a second, much heavier mass scale M_H = 690 +/- 30 GeV associated with the zero-point energy which determines its depth. In spite of its large mass, however, the heavier state would couple to longitudinal W's with the same typical strength as the low-mass state at 125 GeV and thus represent a relatively narrow resonance mainly produced at LHC by gluon-gluon fusion. After summarizing the general aspects, I will consider 4 samples of LHC data (2 from ATLAS and 2 from CMS) which suggest a new resonance with a combined mass value of 691(10) GeV.Since the considered measurements have a negligible correlation and since, when comparing with a definite theoretical prediction, local excesses are not downgraded by the so called look-elsewhere effect, the cumulated statistical significance is now substantial. The issue of the second resonance could thus definitely be settled by just adding one or two crucial, missing samples of RUN2 data.
2023-03-10 (Friday)
room B2.38, Pasteura 5 at 10:15
dr hab. Krzysztof Rolbiecki (IFT UW)LHC searches beyond simplified models
In this talk I will discuss a concept of simplified models which is used for interpretation of searches for new physics at the LHC. I will discuss limitations of this approach and the need for reinterpretation of results. Then I will introduce several computer programs that are used to reinterpret ATLAS and CMS searches beyond Standard Model physics. Finally I will show recent examples of reinterpretation efforts from the theory community.
2023-03-03 (Friday)
room B2.38, Pasteura 5 at 10:15
dr inż. Magdalena Kuich (IFD UW)Warsaw Active-Target Time Projection Chamber - a powerful tool to study nuclear reactions of astrophysical interests but not only
Crucial interests in nuclear astrophysics are (p,γ) and (α,γ) reactions. In particular, those that regulate the ratio of C and O and those that burn 18O and, therefore, regulate the ratio between 16O and 18O in the Universe. Such reactions in the stars happen at energies well below the Coulomb barrier and the respective cross-sections are incredibly small, often below the experimental reach. Therefore, the available experimental results on cross-sections for low energies are very sparse, and theoretical extrapolations are burdened with large uncertainties. An opportunity to elude a part of the experimental limitations is to study the time-reversal reaction, i.e. photo-disintegration. For this purpose, a novel active-target Time Projection Chamber (TPC) optimised for experiments with high-intensity γ-ray beams was developed and built at the Faculty of Physics, University of Warsaw. Several experiments with the Warsaw active-target TPC were performed in the summer of 2021 at the IFJ PAN Cracow and in the spring and summer of 2022 at HIgS, TUNL, USA.Preliminary results of the performed measurements at IFJ and HigS will be presented and an outlook on future experiments will be given.
2023-02-07 (Tuesday)
room B2.38, Pasteura 5 at 11:15
prof. Juergen Reuter (DESY Theory Group, Hamburg)Vector Boson Scattering at the LHC - Precision, Polarization and New Physics Searches
The scattering of electroweak vector bosons (VBS) is at the heart of electroweak symmetry breaking: it demonstrates the unitarization by the Higgs exchange, which is a subtle cancellation of quadratic energy rise. This, together with the fact, that VBS covers the multi-TeV energy range make it an ideal tool to search for new physics. In this talk, I will discuss the status of the SM precision calculation, also for polarized VBS. Three types of new physics signal modelling will bepresented: SM effective field theories (SMEFT), simplified models, and specific new physics models important for VBS. Pros and cons of these modellings will be discussed.
2023-01-27 (Friday)
room B2.38, Pasteura 5 at 10:15
dr hab. Grzegorz Grzelak (IFD UW)The LUXE - Laser und XFEL Experiment-towards non-perturbative QED
The seminar will introduce LUXE, "Laser Und XFEL Experiment", currently being developed at DESY in Hamburg, an experiment that aims to use the high-quality electron beam of the European XFEL facility and a high-power optical laser.The scientific goal of the experiment is to study quantum electrodynamics in the largely unexplored territory, in the regime of strong fields, close to and beyond the Schwinger limit, revealing the non-perturbative face of QED and going beyond the formalism of linear equations of quantum electrodynamics.The seminar will also introduce the experimental setup:beam extraction from the European XFEL Linac, requirements for a high power laser and precise detectors optimized to measure electrons, positrons and photons including contribution to the experiment form the University of Warsaw.
2023-01-20 (Friday)
room B2.38, Pasteura 5 at 10:15
Małgorzata Kazana (NCBJ)How to see Dark Matter at LHC?
During the seminar, the review of searches for Dark Matter at LHC will be given.
2023-01-13 (Friday)
room B2.38, Pasteura 5 at 10:15
dr hab. Michał Bluj (NCBJ)Portrait of the Higgs boson for 10th anniversary of its discovery
A discovery of a Higgs boson was announced by the ATLAS and CMS experiments 10 years ago. In this talk I will summarise knowledge on its properties.
2022-12-16 (Friday)
room B2.38, Pasteura 5 at 10:15
dr hab. Artur Kalinowski, prof. UW (IFD UW)Najnowszy pomiar masy kwara top w CMS
Latest CMS result on top mass
Omówię ostatni pomiar masy kwarka top w eksperymencie CMS. Pomiar ten jest obecnie najbardziej precyzyjnym pojedynczym pomiarem masy topu. Seminarium zakończę uwagami na temat wpływu masy kwarka top na stabilność próżni.
I will present a recent measurement of the top quark mass made by the CMS Collaboration. The measurement is the current most precise single top quark measurement. I will finish with some remarks on the importance of the top mass for the vacuum stability.
2022-12-02 (Friday)
room B2.38, Pasteura 5 at 10:15
Kamil Skwarczyński (NCBJ)New T2K Oscillation Results
T2K is a long-baseline neutrino oscillation experiment, which studies the oscillations of neutrinos from a beam produced using the J-PARC accelerator chain. The neutrino beam propagates over 295 km before reaching the Super-Kamiokande detector, where they can be detected after having oscillated. The ability of the experiment to run with either neutrino beams or anti-neutrino beam makes it well suited to study the differences between the oscillations of neutrinos, in particular to look for a possible violation of CP symmetry in the lepton sector. T2K has produced a new analysis of its first 10 years of data, with improved models to describe neutrino interactions and fluxes as well as additional samples of near and far detector events. We will present the results of the measurement of the parameters describing neutrino oscillations obtained with the new analysis.
2022-11-25 (Friday)
room B2.38, Pasteura 5 at 10:15
dr. Darko Donevski (NCN grant holder at the NCBJ Astrophysics Division BP4)The James Webb Space Telescope - new infrared vision of the early Universe
The James Webb Space Telescope (JWST) is the largest space telescope ever launched, and it will be a giant leap forward in our quest to understand the Universe and our origins. Delivery of the first scientific data in themid-2022 demonstrated unprecedented imaging and spectroscopic capabilities in the near to mid-infrared bands, with a sensitivity that is orders of magnitude higher than current facilities. Undoubtedly, in the years to come, JWST will open a huge, new discovery space in most areas of astronomy and astrophysics. In this seminar I will present the first results and big science questions that JWST observations are expected to answer. The particular emphasis will be given to the projects related to the galaxies in the early Universe.
2022-10-28 (Friday)
room B2.38, Pasteura 5 at 10:15
dr Joanna Zalipska (NCBJ)Neutrino news from summer conferences
This seminar will summarize results related to neutrino physics from summer conferences such as Neutrino 2022 and ICHEP 2022. The overview of the Long Baseline neutrino experiments current (T2K, Nova) and future (Hyper-Kamiokande, DUNE) will be presented. On top of it the direct neutrino masses searches will be discussed showing latest results from KATRIN experiment together with plans of future experiments.
2022-10-21 (Friday)
room B2.38, Pasteura 5 at 10:15
prof. dr hab. Aleksander Filip Żarnecki (IFD UW)ECFA workshops on e+e- Higgs/EW/Top factory
Based on the recommendations of the Update of the European Strategy for Particle Physics, the European Committee for Future Accelerators (ECFA) has decided to organise a series of workshops on physics studies, experiment design and detector technologies towards a future electron-positron Higgs/EW/Top factory. Three Working Groups were established, led by conveners from both experiment and theory, on Physics Potential (WG1), Physics Analysis Methods (WG2) and Detector R&D (WG3). The first community-wide plenary ECFA workshop e+e- Higgs/EW/Top factory took place recently at DESY, Hamburg. I will report on the DESY meeting and the ECFA initiative in general.
2022-10-14 (Friday)
room B2.38, Pasteura 5 at 10:15
prof. dr hab. Andrzej Kupść (Uppsala University & BP3 NCBJ)Studies of hyperon decays using hyperon-antihyperon pairs from J/psi decays
Hyperon-antihyperon pairs from decays of vector charmonia are spin entangled. Furthermore, if the charmonia are produced in electron-positron collisions the hyperons can be polarized. Millions of the hyperon--antihyperon pairs events are available in the world's largest data of 10^10 J/psi and 2.7x10^9 psi(2S) collected at the BESIII experiment . The entangled pairs are used for precision determination of hyperon and antihyperon decay amplitudes and to test CP symmetry in the decays. The hyperon CP-symmetry tests are complementary to the direct CP-violation studies in kaon decays. I will present multi-dimensional analysis methods, developed by the Uppsala and Warsaw groups, that make use of the polarization and entanglement to achieve best sensitivity in the hyperon-decay measurements. Recent BESIII results obtained using these methods include studies of J/psi decays into Lambda-antiLambda and Xi- anti Xi+ published in Phys. Rev. Lett. and Nature, respectively. For the cascade decay chain, the exclusive measurement allows for three independent CP tests and determination of the strong and weak phase differences in the decay amplitudes.
2022-10-07 (Friday)
room B2.38, Pasteura 5 at 10:15
prof. dr hab. Barbara Badełek (IFD UW)COMPASS - a versatile facility at CERN
The purpose of COMPASS is the study of hadron structure and hadron spectroscopy with high intensity muon and hadron beams.The Collaboration is formed by about 200 physicists from 25 countries.The facility was approved 25 years ago and the physics experiments started in 2002 with a muon beam, polarised proton and deuteron targets. These semi-inclusive deep inelastic scattering (SIDIS) reveals a detailed quark-gluon structure of the nucleon, in particular the gluon polarisation and transverse-momentum-dependent correlations.The years 2008 and 2009 were dedicated to the hadron spectroscopy programme with pion and proton beams scattering off a liquid hydrogen target and nuclear targets. An unprecedented amount of data was collected and showed subtle details of the light-meson spectrum. A dedicated study of the pion polarisability using Primakoff scattering of pions from heavy nuclei was also performed.Phase II of COMPASS commenced in 2014 and is primarily devoted to the transverse and 3D structure of nucleons using Deeply Virtual Compton scattering (DVCS), Hard Exclusive Meson Production (HEMP), SIDIS and polarised Drell-Yan (DY) reactions.I shall repeat a plenary talk which I gave in September 2022 at the "Quarks in Nuclear Physics" conference in Florida (USA).