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Experimental Particle and Astro-Particle Physics Seminar

Monday 14:00

UZH Irchel Y16 G05

Attendance sheet (PDF, 55 KB) for Master and PhD students

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Current Program - Spring 2019

18 February Lindley Winslow (Massachusetts Institute of Technology) Axion Dark Matter and Neutrinoless Double-Beta Decay: New Techniques for New Physics

Two of the biggest open questions in the Standard Model of Particle Physics are: is the neutrino its own antiparticle, a Majorana particle, and is Peccei-Quinn Symmetry with the resulting axion the solution to the strong CP problem. The answer to these questions is a portal to new physics and the answer to the even bigger questions of the generation of the matter-antimatter asymmetry and the nature of dark matter. My group works to address these questions with searches for neutrinoless double-beta decay and ultra-light axions. In this talk, I will review the physics that connects these two efforts, the current status of the fields, and our R&D efforts towards the next-generation experiments.
talk (PDF, 118 MB) Michelle Galloway
21 February - special seminar

Ohkyung Kwon (University of Chicago)

An Experimental Probe of Quantum Correlations in Space-Time at the Fermilab Holometer


What is Fermilab, a 50-year old nuclear physics laboratory, doing with a laser interferometer? Moving past the quantum physics of particles, we have created a new research program to probe the quantum mechanics of space-time -- the "background" in the framework of QFT. Applying LIGO's technology to a new regime, we built the Holometer, a pair of 40m-long, co-located but independent high-power Michelson interferometers. Their signals are sampled at a frequency far exceeding the 8MHz inverse light crossing time of the optical layout, for broad-band cross-correlation measurements of differential position that are both timelike and spacelike across the physical system. This allows sensitivity to nonlocal phenomena such as an entanglement of space-time, beyond the local metric fluctuations or stochastic gravitational waves measured at LIGO or GEO600. With 10^29 photons, the cross spectral density integrates down to 0.1 Planck time in dimensionless strain units.

In this talk, I will describe the design concept and experimental system, and present the current status of our analysis and systematics. I will survey our phenomenological framework for interpreting this data -- a hypothesis about a relational space-time emergent from a quantum system, with the information delocalized according to EPR-like causal structures. If our signature is verified, it offers a potential pathway to new clues about the black hole information problem, the nature of dark energy, and the holographic principle. I will also discuss possible concordant signatures in the latest data on the cosmic microwave background (Planck) and galaxy density distributions (DES).

talk (PDF, 42 MB) Florencia Canelli
25 February Luigi Marchese (University of Oxford) Higgs boson width at the LHC

In the Standard Model the Higgs boson is a very narrow resonance and therefore measuring its width is challenging.
How can we constrain the Higgs boson total width at the LHC?
Presently, the best limits on the Higgs boson total width at the LHC are set using the off-shell Higgs production and decay to ZZ in the four-lepton or two-lepton-two neutrino final state and decay to WW in the two-lepton-two neutrino final state.
A review of all measurements performed by the ATLAS collaboration with Run 1 data and Run 2 data collected in 2015 and 2016 is presented.
talk (PDF, 12 MB) Florencia Canelli
04 March        
11 March Hans Dembinski (Max Planck Institute, Heidelberg) From the Muon Puzzle in cosmic-ray induced air showers to the proton-oxygen collisions at the LHC

There is a glaring discrepancy in cosmic-ray induced air showers: the measured muon number disagrees with simulations. Evidence has popped up sporadically in the last twenty years, but it was not clear whether the problem is on the experimental or the theory side. Comparing muon measurements from different experiments is complicated, since no two experiments measure exactly the same. In 2018, a new collaboration was formed by members of eight leading cosmic ray experiments to combine their muon data in a new way for a special muon report. In this report, the Muon Puzzle was firmly established as an experimental reality, which means we have a problem on the theory side. To resolve theoretical uncertainties, a group of theorists and experimentalists is promoting measurements proton-oxygen collisions at the LHC and achieved an intermediate success: such collisions are planned for 2022. This talk will trace the evidence on the Muon Puzzle, explain the potential impact of solving it, and show the theoretical leads which point to proton-oxygen collisions at the LHC as the means to resolve it.
talk Alison Mitchell
18 March        
25 March Imre Bartos
(University of Florida)

The Road

Ahead of  Multimessenger Astrophysics Following LIGO/Virgo’s Recent Discoveries

The recent discoveries of gravitational waves unveiled numerous opportunities in astrophysics, as well as in the study of the cosmos and the laws of physics. I will outline the opportunities and challenges in multimessenger observations that will broaden our horizon with gravitational waves in the next few years. In particular, we can expect the proliferation of detected binary neutron star and binary black hole mergers, along with new large-scale observatories joining the effort to identify the electromagnetic and neutrino counterparts of these events with low latency. Frequent multimessenger observations will enable the study of exceptional events, source populations, and sufficient statistics to probe new physics and cosmology.  Extracting the most information out of upcoming observations will require the unified interpretation of a broad range of emission processes from the same source, the use of prior astrophysical information, such as on the host galaxy, to evaluate events, as well as the prioritization of available observational and analytical efforts to the most promising cases.


Shubhanshu   Tiwari  

01 April        
08 April        
15 April Schroedinger colloquium     Laura Baudis / Florencia Canelli
16 April - special seminar

Paula Alvarez Cartelle (Imperial College, UK)

Search for lepton flavour universality violation in B+→K+ℓ+ℓ− decays at LHCb

Recent measurements of observables involving the flavour changing neutral current transition b→sμ+μ− have shown an interesting pattern of tensions with respect to the predictions of the Standard Model (SM). However, the interpretation of these results is limited by our present understanding of the hadronic uncertainties affecting these predictions. Given the lepton-flavour-universal nature of the SM, observables such as RK=BR(B+→K+μ+μ−)/BR(B+→K+e+e−), so-called Lepton Flavour Universality ratios, profit from large cancellation of the theory uncertainties and provide a very sensitive probe for physics beyond the SM.

The previous measurement of the ratio RK performed by the LHCb collaboration, using Run 1 data, found a value compatible with the SM expectation at the 2.6σ level. In this seminar, a new measurement of RK at the LHCb experiment will be presented. The new measurement reanalyses the data recorded by LHCb during Run 1, and adds data collected during 2015 and 2016. The total dataset is double the size of that previously analysed.

  Gino Isidori/ Nico Serra / Rafael Silva Coutinho
22 April        
29 April Cancelled:
Fabio Mantovani (University of Ferrara)

Geoneutrinos in JUNO

In next decade the 20 kton liquid scintillation detection volume of JUNO experiment in China will measure the geoneutrino signal with a sensitivity never reached by ongoing (Borexino and KamLAND) and under construction (SNO+) experiments. Geoneutrinos produced in beta minus decays along the 238U and 232Th decay chains inside the Earth provide an exceptional probe for the study the global properties of our planet. What is the potential of geoneutrino measurements in JUNO for constraining the radiogenic contribution to terrestrial heat production? Will JUNO data be able to provide any insights on the building blocks of the Earth and its evolution? What are the next challenges for geophysicists and geochemists involved in the studies of heat generating elements in the terrestrial crust and mantle? The talk will focus on these questions, reviewing the recent geoneutrinos experimental results from KamLAND and Borexino and emphasizing how the scientific and technological progresses in JUNO is opening a new exciting scientific season, who is involving particle physicists and Earth scientists.

  Giovanni Volta
06 May        
13 May Schroedinger colloquium     Titus Neupert
20 May

Andrei Puiu
(University of Milano-Bicocca)

Direct Measurement of the neutrino mass with HOLMES

Measuring the neutrino mass is one of the most compelling challenges of modern physics.
Neutrinos are the second most abundant particle in the universe, yet one of the most mysterious. Since their existance was postulated in 1930 by Pauli, several experimental efforts have been made to detect them at first and subsequently, to a better understanding of the neutrino properties and nature.
Today, thanks to even more precise oscillation measurements we have established that neutrinos have a very tiny, yet larger than zero mass.
Several experiments have been performed and are being set-up in order to assess this important issue, which not only could shed light on some limits of the Standard Model of Elementary Particles, but on the history and the structure of the universe as well.
The direct, or kinematic, measurement of the neutrino mass is a unique tool, given that no complex theoretical model is necessary to probe the mass of the neutrino.
Many experimental challenges are to be faced though, so experimentalists and theoretcians across the world are working on solving new issues in order to push the limit on the neutrino mass lower and lower, and possibly measuring this important parameter soon.
Within this framework lies HOLMES, an experiment aiming at performing a direct neutrino mass measurement from the Electorn Capture spectrum of 163Ho. HOLMES will deploy a large array of 1000 low temperature (~10 mK) calorimeters with Transition Edge Sensors coupled to Ho-implanted gold absorbers.
Its target activity of 300 Bq/detector poses serious experimental challenges both in detector and readout performance.
I will try to give an overview of the neutrino mass searches, focusing on the direct mass measurements with HOLMES and other competitor experiments.

talk (PDF, 8 MB) Chiara Capelli
27 May

Pablo Martinez Ruiz Del Arbol (ICFA, SPain)

Muon Tomography

The Earth is being constantly bombarded by high energy protons interacting with the atmosphere and producing a flux of 10000 muons per minute and squared meter. These muons interact with matter through ionization and multiple scattering being these processes highly dependent on the properties of the material they are crossing. The measurement of the attenuation and angular deviation of the muons can be used to infer the geometry and densities of the materials. This new technique is being used nowadays in applications such as volcanology, archeology, civil engineering, security, nuclear industry and the heavy industry. In this context, Muon Systems emerged as a company to apply these principles to the industry, and more particularly to the preventive maintenance of critical industrial equipment such as pipes and cauldrons. After working during 2 years in the development of suitable muon detectors and algorithms, the company will start its first pilot project measuring the thickness of pipes in a petrol processing factory in the north of Spain. This seminar will review the principles of muon tomography, its applications and how it can be used to improve several industrial processes.

talk (PDF, 11 MB)

Annapaola de Cosa


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