HIP NEWS April 25th 2016
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DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS
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Tuesday 26 April 2016 at 10.15 in A315
Thomas Konstandin (Desy)
Effective actions in particle physics and cosmology

Abstract: Effective actions are an invaluable tool in particle physics and cosmology. For example, they are used to determine properties of the Higgs or the stability of the vacuum. Other applications include the sphaleron rate in the early universe or the characteristics of the electroweak phase transition. In this talk, I will give an extensive introduction to the topic and finally touch on some advanced questions as infrared problems or gauge-dependence.

COSMO-seminar
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Wednesday 27 April 2016 at 14.15 in A315
Steen Hansen (DARK, Copenhagen)
Pancakes in space

Abstract: The cosmological web consists of equilibrated galaxies and clusters of galaxies, one dimensional filaments, two dimensional sheets (also called Zeldovich pancakes) and three dimensional voids.

I will discuss the first detection of two Zeldovich pancakes near the Coma cluster. These sheets/pancakes, which are few Mpc wide and about 10 Mpc long, are very cold structures with velocity dispersion about 100 km/sec. In comparison, groups of galaxies have dispersions around 300 km/sec.

By measuring the departure from a pure Hubble flow of the galaxies belonging to the sheets/pancakes, one can determine the virial mass of the nearby galaxy cluster, and I will discuss how this method complements other methods.

Finnish for international personnel, summer 2016
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The summer 2016 course programme is available at helsinki.fi/finnishcourses
https://flamma.helsinki.fi/en/notifications/finnishsummer2016

Visitors
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S. Hansen 27.4. – 29.4. (FM)
L. Boldizsar 13.4. – 26.4. (EB)
M. Hindmarsh 29.4. – 12.6. (KR)
T. Konstandin 26.4. – 27.4. (OL)
A. Lopez 29.4. – 13.6. (MH, KR)

HIP NEWS April 18th 2016
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DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS
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Tuesday 19 April 2016 at 10.15 in A315
Aurora Meroni (Odense)
Neutrino physics: status and quests for the future

Abstract: Neutrino physics has entered the precision era. Nevertheless many questions still remain without an answer. We know that the SM cannot be the ultimate theory, since a so-called “elusive” sector is completely missing: neutrinos are not properly included since we cannot describe their mass. Moroever, the nature, Dirac or Majorana, of the three light active neutrinos nuj (j = 1,2,3) with definite mass mj is unknown. I will review unknown properties of neutrinos and how possibly detect some of them. In particular I will define a theoretical framework and deduce the conditions under which multi-messenger astronomy can constrain neutrino masses and unveil their ordering. The framework uses time differences between the arrival of neutrinos and the other two light messengers, i.e. light and gravitational waves, emitted by astrophysical catastrophes.

COSMO-seminar
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Wednesday 20 April 2016 at 14.15 in A315
Adam Amara (ETH Zurich)
Cosmology and the Dark Energy Survey

Abstract: The Dark Energy Survey (DES) is a 5000 square degree survey targeting dark matter and dark energy science. This year sees the release of the first science results from the DES collaboration using data taken during science verification. I plan to present these new results, which include dark matter maps, cosmology constraints and new discoveries such as the new strong lens systems being found. I will also give an update on the progress of the main science survey, which is still ongoing.

Finnish for international personnel, summer 2016
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The summer 2016 course programme is available at helsinki.fi/finnishcourses
During the summers months the courses are intensive courses, with meetings four times a week. The first courses begin on 30 May. Courses are filled on a first-come first-served basis.
https://flamma.helsinki.fi/en/notifications/finnishsummer2016

Visitors
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A. Amara 19.4. – 21.4. (FM)
L. Boldizsar 13.4. – 26.4. (EB)
A. Meroni 18.4. – 20.4. (AV)
F. Sannino 18.4. – 19.4. (KT)

HIP NEWS April 11th 2016
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DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS
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Tuesday 12 April 2016 at 10.15 in A315
Louis Lyons (Imperial College)
Statistical Issues in Searches for New Physics

Abstract: Given the cost, both financial and even more importantly in terms of human effort, in building High Energy Physics accelerators and detectors and running them, it is important to use good statistical techniques in analysing data. This talk covers some of the statistical issues that arise in searches for New Physics. They include topics such as: Blind Analysis. How should we deal with the `Look Elsewhere Effect’? Should we insist on the 5 sigma criterion for discovery claims? Significance P(A|B) is not the same as P(B|A). The meaning of p-values. What is Wilks’ Theorem and when does it not apply? Dealing with systematics such as background parametrisation. Coverage: What is it and does my method have the correct coverage? Upper Limits. The use of p_0 vs p_1 plots. Higgs search: Discovery and Spin.

Thursday 14 April 2016 at 10.15 in A315: Guy Moore (Darmstadt)
Relating the Axion Mass and Dark Matter Density

Abstract: QCD appears to allow for large parity and time-reversal violating effects, which are in fact unmeasurably small. The simplest dynamical model to explain this predicts a new particle, the Axion, which is also an excellent dark matter candidate. Under reasonable assumptions it should be possible to predict the relation between the axion’s mass and its dark matter abundance. I will discuss the interesting physics we need to make this prediction concrete — axionic string networks and topological susceptibility.

COSMO-seminar
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Wednesday 13 April 2016 at 14.15 in A315
Matti Herranen (Jyväskylä)
Nonequilibrium QFT approach to leptogenesis
Abstract: he observed baryon asymmetry of the Universe may have been produced dynamically in the very early Universe by a baryogenesis via leptogenesis process from the CP- and lepton number violating decays of heavy right-handed neutrinos. For reliable calculations of the baryon asymmetry generated in leptogenesis first principle methods of nonequilibrium quantum field theory are required.

We construct a transport theory of leptogenesis based on the Schwinger-Keldysh or Closed Time Path (CTP) formalism of nonequilibrium QFT. The resulting kinetic equations incorporate finite density medium effects and quantum coherence effects and therefore provide a generalization to standard (quantum) Boltzmann equations. We find that the finite density corrections from loop integrals typically lead to an enhancement of the asymmetry. In the resonant regime with nearly degenerate right-handed neutrino masses, our results confirm the well-known resonant enhancement of CP-violation, however, novel effects from the flavour oscillations can be important in the dynamics.

Wednesday 13 April 2016, Upcoming events for international staff
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Sign up in http://www.helsinki.fi/trainingcalendar ( Staff Training Calendar HENKKA) or via https://elomake.helsinki.fi/lomakkeet/48601/lomake.html

Last sign-up date: 17.04.2016: Completing Your Tax Return Form – Veroilmoitus in English
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Sign up in http://www.helsinki.fi/trainingcalendar ( Staff Training Calendar HENKKA)

Visitors
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L. Boldizsar 13.4. – 26.4. (EB)
M. Herranen 12.4. – 13.4. (FM)
A. Meroni 18.4. – 20.4. (AV)
G. Moore 13.4. – 15.4. (AV)
D. Varga 13.4. – 15.4. (EB)
M. Vargyas 11.4. – 15.4. (EB)

HIP NEWS April 4th 2016
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DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS
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Monday 4 April 2016 at 10.15 in A315 Note Day!
Mirko Berretti (HIP/Totem)
Exclusive processes with TOTEM and CT-PPS: results, perspectives and experimental challenges

Abstract: The latest results and the physics potential of the TOTEM experiment at the LHC will be presented. This include searches for glueballs and new physics together with CMS and a deeper understanding of elastic scattering. For LHC RUN-2, a joint CMS-TOTEM project (CT-PPS) has been approved to study exclusive particle production at the highest LHC luminosity. With the recent indication by the CMS and ATLAS experiments of a possible resonance in the 750 GeV mass region, the CT-PPS, initially designed to search for anomalous gauge boson quartic couplings, will give a relevant contribution in a possible confirmation and study of this new resonance. I will review the CT-PPS status and plans for 2016 LHC running.

In the second part of the seminar I will concentrate on the new detectors designed to precisely measure the time-of-flight of the scattered protons produced in such exclusive processes at medium and high luminosity to be able to reject pile-up. Timing detectors based on diamond sensors have been developed by TOTEM and will be used in the first phase of the CT-PPS project. I will summarize the detector development, performance and perspective for this promising technology.

COSMO-seminar
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Wednesday 6 April 2016 at 14.15 in A315
Maria Archidiacono (Aachen University)
Efficient calculation of cosmological neutrino clustering

Abstract: Within the next few years cosmological structure formation will be probed in greater detail than ever before by new and very large surveys, most notably EUCLID and LSST. While this opens great possibilities for probing for example dark energy and the mass of neutrinos, it also puts very stringent requirements on theoretical calculations of cosmological observables, such as the matter power spectrum. In this regard, the treatment of massive neutrino is particularly challenging both in N-body simulations and in linear theory Boltzmann codes. In this talk I will present a new approximation to the third moment of the Boltzmann hierarchy and demonstrate that with this new approximation the neutrino power spectrum can be calculated with a precision of a few percent. Then I will discuss an extremely efficient way of calculating the neutrino power spectrum in the regime of non-linear dark matter clustering.

Wednesday 13 April 2016, Upcoming events for international staff
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Sign up in http://www.helsinki.fi/trainingcalendar ( Staff Training Calendar HENKKA) or via https://elomake.helsinki.fi/lomakkeet/48601/lomake.html

Visitors
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M. Archidiacono 5.4. – 8.4. (FM)
P. Dendooven 24.2. – 6.4.
G. Moore 13.4. – 15.4. (AV)