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Calendar of Physics Talks Vienna
| Precision measurements with the ATLAS detector at the LHC and tuning of Monte Carlo simulations |
| Speaker: | Torr Fishman (University of Sheffield) |
| Abstract: | This paper presents three bias correction techniques applied to ATLAS Run 2 Monte Carlo (MC) simulations and detector data. The MC and data is taken from pp collisions from the Large Hadron Collider (LHC) at a centre of mass energy of âs = 13 TeV and integrated luminosity of 139 fbâ1. Correction techniques are applied in control regions to derive calibrations for matching MC to data. In this paper, the corrections are specifically applied to the uncertainty of the ratio between charge and momentum, Ï(q/p), of muons decayingfrom Z â µµ. The corrected inputs of Ï(q/p) can then be used in the Z boson mass constraint to increase the resolution of Higgs boson mass measurements from H â ZZâ â 4l decays. Histograms have been plotted using Python and ROOT to present the data, initial MC, and corrected MC probability density functions (PDFs). The bias corrections discussed include linear scaling, |
| Date: | Tue, 29.03.2022 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | Seminarraum ATI |
| Contact: | Julian Leonard |
| Fast Scrambling due to Rotating Shockwaves in Rotating Black Holes. |
| Speaker: | Rohan Poojary (TU Wien) |
| Abstract: | We study the perturbation due to rotating shockwaves in BTZ geometries at late times and analyse the change in Mutual Information between the two subsystems belonging to the dual CFT$_L$ and CFT$_R$.
We find that the scrambling of Mutual Information is in general governed by the Lyapunov index $\lambda_L$ which is bounded by $\kappa=\frac{2\pi}{\beta(1-\mu\mathcal{L})}\geq \frac{2\pi}{\beta}$ where $\mu=\rmi/\rpl$ and $\mathcal{L}$ is
the angular momentum of the shockwave. For the special case of $\mathcal{L}$=$1$ we find the Mutual Information analytically, characterized by $\lambda_L=\kappa/2$ and with the scrambling time for large black holes $t_*=\frac{\beta(1-\mu)}{\pi}\log S$.
If time permits I would also discuss consequences for the near horizon effective theory relevant to our observations. |
| Date: | Tue, 29.03.2022 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Sem.R. DA, gruen 05 (TU Wien, Freihaus) |
| Contact: | D. Grumiller, S. Fredenhagen, E. Battista, R. Ruzziconi |
| Energy loss of charged particles in 2D materials, using the oscillator model |
| Speaker: | Juana L. Gervasoni (Centro Atomico Bariloche, Comision Nacional de Energia Atomica, Instituto Balseiro, Universidad Nacional de Cuyo, S.C. de Bariloche/Argentina) |
| Abstract: | Adapting the oscillator model from [1] to a mono-atomic layer, we derive relativistic analytical expressions as a function of the relevant parameters of the process.
We develop the model for a wide range of incident energies and considering both parallel and perpendicular trajectories. We obtain several useful analytical expressions for the energy loss considering isotropic and anisotropic in-plane oscillators, for parallel and perpendicular trajectories of the particle.
We notice that in an anisotropic 2D-oscillators system, the energy loss due to single oscillator (and therefore the integrated quantities as stopping power and total energy loss) presents a reduction with respect to the isotropic case, especially in the parallel trajectory. We ascribe this effect to the lower availability of oscillation modes, and hence to a reduction of the interaction channels [2].
Finally, we r |
| Date: | Tue, 29.03.2022 |
| Time: | 16:00 |
| Location: | TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner HauptstraÃe 8-10 Yellow Tower âBâ, 5th floor, SEM.R. DB gelb 05 B; The seminar will be also held as a Zoom Meeting https://tuwien.zoo |
| Contact: | Ao.Univ.Prof. Dr. Wolfgang WERNER |
| HLbL contribution to muon g-2 at short distances |
| Speaker: | Antonio Rodriguez (IJCLab, Paris) |
| Abstract: | One of the main contributions to theoretical uncertainties in muon g-2 comes from Hadronic Light-by-Light.
In order to achieve a significant reduction of them in the data-driven approach we need a better understanding of the different contributions from intermediate and high-energy regions.
In this talk I focus on the contributions associated to large loop momenta. It is shown how a precise Operator Product Expansion can be applied in this regime.
The massless quark loop is shown to give the leading order. Both gluonic corrections and power corrections are assessed. They are found to be numerically small.
The gluonic correction is found to be negative and the leading power correction is observed to scale as the pseudoscalar mass squared. The associated muon g-2 contributions are also displayed. |
| Date: | Tue, 29.03.2022 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schrödinger-Hörsaal, Faculty of Physics, Boltzmanngasse 5, 5. Stock ZOOM https://univienna.zoom.us/j/93427906843?pwd=YjhSejdUVW16QjVQYUh5TVNSNFNhQT09 Meeting ID: 934 2790 6843 Passcode: 073703 |
| Contact: | A. Hoang, M. Procura |
| Possible scale invariant effects in our low density Universe |
| Speaker: | Andre Maeder (Geneva) |
| Abstract: | An empty Universe would be scale invariant, as shown by both Maxwell equations and General Relativity.
The question arises on how much matter is necessary to break scale invariance in the Universe.
On the basis of scale invariant models based on expressions derived by Dirac (1973), we show that scale invariant effects rapidly decline
to zero for cosmological models with a density between zero and the critical one. For a density parameter Omega_m=0.3, some limited effects are remaining,
which correspond to the observed accelerated expansion. Several cosmological tests are consistent, e.g. the growth of density fluctuations is boosted in the scale invariant context,
a large M/L ratio is derived for clusters of galaxies, flat rotation curves are predicted in galaxies with a proper account of the radial acceleration relation (RAR). |
| Date: | Thu, 31.03.2022 |
| Time: | 15:00 |
| Duration: | 60 min |
| Location: | ZOOM https://univienna.zoom.us/j/6540036841?pwd=SytyVkZJZzNyRG9lMm13ejlHeHRRUT09 Meeting ID: 654 003 6841 Passcode: Gs4brS |
| Contact: | P. Chrusciel, D. Fajman |
| Active and machine learning for quantum data |
| Speaker: | Annabelle Bohrdt (Harvard University) |
| Abstract: | Recent advances in quantum simulation experiments have paved the way for a new perspective on strongly correlated quantum many-body systems. Digital as well as analog quantum simulation platforms are capable of preparing desired quantum states, and various experiments are starting to explore non-equilibrium many-body dynamics in previously inaccessible regimes in terms of system sizes and time scales. State-of-the art quantum simulators provide single-site resolved quantum projective measurements of the state. Depending on the platform, measurements in different local bases are possible. The question emerges which observables are best suited to study such quantum many-body systems.
In this talk, I will cover two different approaches to make the most use of these possibilities. In the first part, I will discuss the use of machine learning techniques to study the thermalization behavior of |
| Date: | Fri, 01.04.2022 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | ATI Hörsaal/https://tuwien.zoom.us/j/93672218922?pwd=dEZNQ2liVzRNNURvNmVWVE5KUWRiQT09 |
| Contact: | Julian Leonard |
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