Wydział Fizyki UW > Badania > Seminaria i konwersatoria > Seminarium "High Energy, Cosmology and Astro-particle physics (HECA)"

Seminarium "High Energy, Cosmology and Astro-particle physics (HECA)"

2020/2021 | 2021/2022 | 2022/2023 | 2023/2024 | 2024/2025 | Strona własna seminarium

Zapraszamy na spotkanie o godzinie 11:15

Jaime Hoefken Zink (Università di Bologna)

The dark in the white: Dark sectors in white dwarf cooling

White dwarfs constitute a fruitful environment to search for dark sectors, i.e. BSM physics. Their extreme conditions due to the high densities and temperatures in their cores together with the seemingly agreement in how to model them make them an ideal scenario for testing BSM models. Two specific models with dark photons will be shown: the Three portal model and Lμ - Lτ, both of which generate an extra contribution for the cooling of hot white dwarfs. For the latter, a first ever computed full calculation will be presented and discussed. Constraints found on the models will be also shown.

https://uw-edu-pl.zoom.us/j/9529812548

Zapraszamy do sali B2.38, ul. Pasteura 5 o godzinie 11:15

Oliver Newton (Center for Theoretical Physics PAN, Warsaw)

Constraints on the properties of nuMSM dark matter using the satellite galaxies of the Milky Way

Low-mass galaxies are powerful tools with which to investigate departures from the standard cosmological paradigm in models that suppress the abundance of small dark matter substructures. One of the simplest metrics that can be used to compare different models is the abundance of satellite galaxies in the Milky Way. Viable dark matter models must produce enough substructure to host the observed number of Galactic satellites. Here, we scrutinize the predictions of the neutrino Minimal Standard Model (nuMSM), a well-motivated extension of the Standard Model of particle physics in which the production of sterile neutrino dark matter is resonantly enhanced by a lepton asymmetry in the primordial plasma. This process enables the model to evade current constraints associated with non-resonantly produced dark matter. Independently of assumptions about galaxy formation physics and the Milky Way halo mass we rule out, with at least 95 per cent confidence, all parametrizations of the nuMSM with Ms ≤ 1 keV. Incorporating physically motivated prescriptions of baryonic processes and modelling the effects of reionization strengthens our constraints and we exclude all models with Ms ≤ 3 keV. Our fiducial constraints do not rule out the putative 3.55 keV X-ray line, if it is indeed produced by the decay of a sterile neutrino. In contrast with other work, we find that the constraints from satellite counts are substantially weaker than those reported from X-ray non-detections.

Zapraszamy na spotkanie o godzinie 11:15

Nicolas Bernal (New York University, Abu Dhabi)

New Avenues For Dark Matter Production

The existence of nonbaryonic dark matter (DM) in the Universe is compelling, as suggested by astrophysical and cosmological observations. The most commonly assumed production mechanism for DM in the early universe corresponds to the weakly interacting massive particle (WIMP) paradigm, in which DM has mass and couplings at the electroweak scale. However, the current null experimental results and severe constraints on the natural parameter space are forcing us to search beyond the standard WIMP paradigm. In this talk, I will review alternative DM production mechanisms in the early universe, both thermal and non-thermal, like the FIMP and the SIMP paradigms. The possible impact of alternative non-standard cosmological scenarios will also be analyzed. Finally, experimental avenues for DM detection are discussed.

The seminar will be held online at:
https://uw-edu-pl.zoom.us/j/9529812548

Zapraszamy do sali B2.38, ul. Pasteura 5 o godzinie 11:15

Rene Poncelet (Institute of Nuclear Physics PAN, Kraków)

Precision phenomenology with heavy-flavour jets at the LHC

Jets are a staple of the research program at high-energy hadron colliders. As suitably defined sets of highly-energetic particles, they constitute a useful tool to establish a link between Quantum Chromodynamics (QCD) of quarks and gluons and the realm of actual strongly-interacting particles, baryons and mesons. Besides the general importance of jets for collider phenomenology, there is a growing interest in studying jet substructure in order to disentangle various QCD effects governing jet dynamics. Final states with jets identified to originate from heavy quarks play a vital role, for example, in understanding the process of heavy-quark fragmentation and the contents of protons at high energy. In this talk I will discuss fixed-order NNLO QCD phenomenology, comparisons thereof to data and infrared-safe flavoured jet algorithms, a non-trivial ingredient in defining useful collider observables.

Zapraszamy do sali B2.38, ul. Pasteura 5 o godzinie 11:15

Benjamin Knorr (Nordita, Stockholm University and KTH Royal Institute of Technology)

Asymptotic Safety meets field redefinitions

Asymptotic Safety is an approach to quantum gravity that solely relies on quantum field theory - it posits that gravity can be quantised by a nonperturbative fixed point of its renormalisation group flow. This rather simple idea is complicated by the fact that in quantum field theory, field redefinitions can be performed without changing physical predictions, encoded for example in scattering amplitudes. As a consequence, only so-called essential couplings need to show such a fixed point - these are the combinations of couplings that are invariant under such redefinitions.In this talk, after a general introduction to Asymptotic Safety, I will discuss recent developments in how to treat the freedom of field redefinitions within nonperturbative renormalisation group flows. In particular, I will show how we can wield this freedom to simplify computations enormously so that more refined approximations can be investigated, consequently improving the accuracy of predictions.

Zapraszamy do sali B2.38, ul. Pasteura 5 o godzinie 11:15

Camilo Garcia-Cely (University of Valencia)

Insights from Axion Dark Matter for the Field of Gravitational Wave Physics

A decade ago, the discovery of gravitational waves marked a crucial milestone in our understanding of the universe. While ongoing efforts primarily focus on detecting gravitational waves at frequencies below a few kHz, a growing interest in exploring higher frequencies is emerging, driven by the potential to observe signals of cosmological origin. In the first segment of my talk, I will delve into the backgrounds for such signals within the Standard Model, with a particular emphasis on the dominant source on Earth: the high-temperature plasma in the Sun. I will highlight the strong parallel with solar axions. Shifting focus in the second part, the discussion will center on experimental proposals for detecting high-frequency gravitational waves. Specifically, I will discuss the potential of axion haloscopes to probe gravitational waves in the 100 kHz-100 MHz range.

Zapraszamy na spotkanie o godzinie 11:15

Hiroki Kawai (University of Tokyo)

Cosmological structure formation with fuzzy dark matter

Note an unusual date and place (room 2.25)! Dark matter is one of the major components in our universe and plays an important role in structure formation. In the standard cosmology, the nature of the dark matter is generally thought that it is cold, and interacts with other matter only through gravity. The so-called Λ Cold Dark Matter (ΛCDM) model can successfully explain a broad range of observations at large length scales. However, there are several discrepancies at small scales, known as small-scale problems. To alleviate these problems, alternative dark matter models such as fuzzy dark matter (FDM) are considered. FDM is a scalar particle coupled to a gravitational field without self-interaction whose mass is around 10^{-22} eV. Due to the small mass of the FDM, the de Broglie wavelength becomes large and wave nature can be seen on a cosmological scale. The wave nature can be seen inside halos, where two unique features can be observed, soliton core and granular structures. In this talk, I first review the standard ΛCDM cosmology and the small-scale problems and introduce the FDM model. Then I show the structures in FDM halos in detail with our studies.

Zapraszamy na spotkanie o godzinie 11:15

Peter Athron (Nanjing Normal University)

From first order cosmological phase transitions to gravitational waves

Online meeting! The 2015 observation of gravitational waves opened up a new window into particle physics. First order cosmological phase transitions are predicted in many extensions of the standard model of particle physics and can generate gravitational wave signatures. Exciting recent results mean that we have now entered an era where data from gravitational wave experiments may be used as possible signals or constraints on particle physics theories. I will discuss these and show how to determine gravitational wave constraints, signals and future discovery projections using the state-of-the-art methods. I will critically evaluate many approximations used in the literature and discuss substantial sources of uncertainty and unknowns.

https://uw-edu-pl.zoom.us/j/9529812548

Zapraszamy do sali B2.38, ul. Pasteura 5 o godzinie 11:15

Gregory Patellis (Technical University of Lisbon)

Reduction of Couplings in the Type-II 2HDM

The idea of reduction of couplings consists in the search for relations between seemingly independent couplings of a renormalizable theory that are renormalization group invariant. In this article, we demonstrate the existence of such 1-loop relations among the top Yukawa, the Higgs quartic and the gauge colour couplings of the Type-II Two Higgs Doublet Model at a high-energy boundary. The phenomenological viability of the reduced theory suggests the value of tan⁡β and the scale in which new physics may appear.

Zapraszamy do sali B2.38, ul. Pasteura 5 o godzinie 11:15

Toni Mäkelä (National Centre for Nuclear Research)

Investigating the reach of LHC neutrino experiments

The recent observation of neutrinos produced at the Large Hadron Collider (LHC), reported by the FASERnu and SND@LHC experiments, has given rise to a novel neutrino physics program for the LHC. In particular, the proposal of a purpose-built Forward Physics Facility (FPF) motivates studies of the discovery potential of these searches. This requires resolving degeneracies between new predictions and uncertainties in modeling neutrino production in the forward kinematic region. Based on a broad selection of existing predictions for the parent hadron spectra at FASERnu and the FPF, we parametrize the expected correlations in the spectra of neutrinos produced in their decays, and use a Fisher information approach to determine the highest achievable precision for their observation. This allows for constraining various physics processes within and beyond the Standard Model, including neutrino non-standard interactions. We also illustrate how combining multiple neutrino observables could lead to experimental confirmation of the enhanced-strangeness scenario proposed to resolve the cosmic-ray muon puzzle during LHC Run 3.

Zapraszamy do sali B2.38, ul. Pasteura 5 o godzinie 11:15

Motoko Fujiwara (Technical University of Munich)

Dark matter heating vs. vortex creep heating in old neutron stars

Dark matter can be captured in a neutron star and deposits its energy into a star. This dark matter heating effect, however, can be observed only if it dominates over other internal heating effects in neutron stars. In this work, as such a internal heating effect, we examine the frictional heating caused by the creep motion of neutron superfluid vortex lines in the neutron star crust. The luminosity of this heating effect is controlled by the strength of the interaction between the vortex lines and nuclei in the crust. We estimated this luminosity in two approaches; (1) the estimation through the temperature observation of old neutron stars and (2) the estimation from the many-body calculation of a high-density nuclear system. We find that both approaches suggest that the vortex creep heating dominates over the DM heating. The vortex-nuclei interaction must be smaller than the estimated values by several orders of magnitude to overturn this domination.

Zapraszamy do sali B2.38, ul. Pasteura 5 o godzinie 11:15

Tom Steudtner (Technical University Dortmund)

Weakly coupled asymptotic safety up to 4 loops

In this talk, I will report about the special role of the Litim-Sannino model for the Asymptotic Safety program, and present a high-precision estimate for the conformal window of its interacting UV fixed point. Four loop gauge, three loop Yukawa and three loop quartic beta functions are computed both by a direct loop calculation and by generalizing existing literature results. The UV fixed point and corresponding critical exponents are obtained at N3LO in the conformal expansion. Several approaches to estimate the conformal window are applied, and the phenomena behind the disappearance of the fixed point are discussed.

Zapraszamy na spotkanie o godzinie 11:15

Lei Zu (Purple Mountain Observatory, Nanjing)

Mirror Twin Higgs Cosmology

Cosmology and particle physics are two distinct branches of physics, but they are interconnected in several ways, and cosmological observations can provide valuable insights into particle physics. With the ever-advancing precision of astronomical cosmological observations, the classical LCDM model faces challenges posed by precise data points, including the Hubble tension, S_8 tension, and nHz gravitational waves. Mirror twin Higgs model has been put forward to explain the Higgs hierarchy problem from only particle physics side. Our research indicates that this model not only offers a particle physics solution but also has the potential to alleviate tensions observed in cosmological observations. The introduction of additional dark radiation during the early universe may alleviate the Hubble tension. Twin recombination mechanisms can help explain the S_8 tension. Furthermore, the potential occurrence of a first-order dQCD phase transition could provide an explanation for the nHz gravitational waves detected by Pulsar Timing Arrays. These findings show that cosmology serves as an ideal laboratory for exploring the particle physics.

https://us02web.zoom.us/j/85478248551

Zapraszamy do sali 1.02, ul. Pasteura 5 o godzinie 11:00

Shihwen Hor (University of Tokio)

SPECIAL!!! Minimal Nambu-Goldstone-Higgs in Supersymmetric SU(5)

We revisit the minimal Nambu-Goldstone (NG) Higgs supersymmetric (SUSY) SU(5) grand unified model and study its phenomenological implications. The Higgs sector of the model possesses a global SU(6) symmetry, which is spontaneously broken and results in the Higgs doublets of the minimal SUSY Standard Model (MSSM) as NG chiral superfields. Therefore, the model naturally leads to light Higgs doublets and solves the doublet-triplet splitting problem. Because of the SU(6) symmetry, the couplings of the Higgs sector are tightly restricted, and thus the model is more predictive than the minimal SUSY SU(5). We determine all the grand-unified-theory parameters via the matching conditions of the gauge coupling constants at the unification scale and calculate proton lifetime, confronting this with current experimental bounds. We discuss that this model is incompatible with the constrained MSSM, whilst it has a large viable parameter space in the high-scale SUSY scenario. The perturbativity condition on the trilinear coupling of the adjoint Higgs field imposes an upper (lower) limit on the wino (gluino) mass, implying a hierarchical mass pattern for these gauginos. Future proton-decay searches can probe a large part of the parameter space, especially if the SUSY-breaking scale is ≲100~TeV.

Note the unusual time and place!!!