HIP NEWS October 26th 2015
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DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS
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Tuesday 27 October 2015 at 10.15 in A315
Alexander Merle (MPI, Munich)
Sterile Neutrino Dark Matter: From Particle to Astrophysics and back

Abstract: In the absence of a clear WIMP signal, we should think about alternative candidates for Dark Matter. A very well motivated example is a (up to now hypothetical) sterile neutrino with a mass of a few keV. In this talk, I will give an overview over the topic of keV sterile neutrino Dark Matter, thereby exploring all corners from Dark Matter production in the early Universe over astrophysical bounds and neutrino phenomenology to particle physics model building aspects. While WIMPs are not dead yet, they have to learn how to live in the neighbourhood of serious competitors.

COSMO-Seminar
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Wednesday 28 October 2015 at 14:15 in A315
Tommi Tenkanen (Helsinki)
Cosmic Inflation and Dark Matter

Abstract: We show that dark matter abundance and inflationary scale could be intimately related. Standard Model extensions with Higgs mediated couplings to new physics typically contain extra scalars whose excursions at the end of inflation can be very large. If their coupling to the Standard Model is weak, they will not thermalize and may easily constitute too much dark matter. As an example we consider Standard Model extended by a real singlet scalar and a singlet fermion. We discuss the field dynamics during inflation together with the post-inflationary dark matter production mechanisms and derive stringent constraints on viable mass scales and coupling values.

H2020 Marie Sklodowska-Curie ITN info session for the 2016 call applicants
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Time: 29.10.2015 at 13-15
https://flamma.helsinki.fi/en/researchers/infosession-msca-itn-2016-call-applicants
Registration: https://elomake.helsinki.fi/lomakkeet/64310/lomake.html
Further information on MSCA is available on https://flamma.helsinki.fi/en/EUframeworkprogrammes/HY309934

Particle Physics Day 2015
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Friday 30 October 2015 at 10:15 – 15:00 in Exactum CK112
http://www.helsinki.fi/~hitu_www/hituday_2015.html

Fortcoming training for employees
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Finnish Working Culture 6.11.2015 at 9:00 – 16:00
The course is targeted for all new international employees of the University of Helsinki.
Last sign-up date: 26.10.2015
Sign up in http://www.helsinki.fi/trainingcalendar ( Staff Training Calendar HENKKA)

Visitors
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A. Cabo 2.10. – 27.10. (AT)
D. Daverio 25.10. – 6.11. (KR)
A. Merle 26.10. – 28.10. (TT)
Y. Zhu 28.10. – 30.10. (AV)

HIP NEWS October 19th 2015
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HIP Staff News
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Dr. Mikko Voutilainen has been appointed
as assistant professor (tenure-track)
in experimental particle physics at
the University of Helsinki starting
Nov. 1st, 2015.

DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS
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Tuesday 20 October 2015 at 10.15 in A315
Timo Alho (Reykjavik)
Geometric Algebra: a coordinate free formalism for inner product spaces

Abstract: Geometric Algebra (GA) is a mathematical system defined by
imbuing the vectors of an inner product space directly with the
Clifford algebra generated by the inner product, without considering a
separate representation of the algebra operating on the vectors. This
simple change in point of view gives a system which generalizes
exterior algebra, quaternions, spinors, and many other algebras used in
theoretical physics, while simplifying both concepts and calculations.
This talk will open a brief course on the algebra and its extension to
geometric calculus. During the talk we will primarily give elementary
details of the formalism, with more advanced topics to be handled later
during the course. Some applications are pointed out for motivation.

COSMO-Seminar
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Wednesday 21 October 2015 at 14:15 in A315
Hannu Nyrhinen (Helsinki)
Story of bimetric variational formalism
Abstract: Bimetric variational formalism was introduced a while ago to construct
novel bimetric gravity models. In these models an affine connection is generated
by an additional tensor field which is independent of the physical metric.
In this talk I will describe the ideas behind the bimetric variational formalism
and some results preceding our work (in JCAP05(2015)021). Namely, we addressed
the issue of ghosts plaguing many bimetric models. Previous work had hinted of a
possibility of removing such unstable degrees of freedom from these theories.
I will show how using the ADM decomposition it is possible to study these models
and the behaviour of their degrees of freedom.

H2020 Marie Sklodowska-Curie ITN info session for the 2016 call applicants
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Time: 29.10.2015 at 13-15
https://flamma.helsinki.fi/en/researchers/infosession-msca-itn-2016-call-applicants
Registration: https://elomake.helsinki.fi/lomakkeet/64310/lomake.html
Further information on MSCA is available on
[1]https://flamma.helsinki.fi/en/EUframeworkprogrammes/HY309934

Visitors
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A. Cabo 2.10. – 27.10. (AT)

HIP NEWS October 12th 2015
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DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS
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Tuesday 13 October 2015 at 10.15 in A315
Alejandro Cabo (La Habana, Cuba)
Is a generalized NJL model the effective action of massless QCD?

Abstract: A local and gauge invariant alternative version of QCD for massive fermions introduced in previous works, is considered here to
propose a model which includes Nambu-Jona-Lasinio (NJL) terms in the action. The Lagrangian includes new vertices which at first sight look as breaking power counting renormalizability. However, these terms also modify the quark propagators, to become more convergent at large momenta, thus indicating that the theory is renormalizable. Therefore, it follows the surprising conclusion that the added NJL four fermion terms do not break renormalizability. The approach can also be interpreted as a slightly generalized renormalization procedure for massless QCD, which seems able to incorporate the mass generating properties for the quarks of the NJL model, in a renormalizable way. It also seems to have opportunity to implement Fritzsch’s Democratic Symmetry description of the quark mass hierarchy.

Thursday 15 October 2015 at 10.15 in A315
Tommi Alanne (CP3-Origins, Odense)
Elementary Goldstone Higgs and raising the fundamental scale

Abstract: We study an extension of the scalar sector of the Standard Model (SM) where the observed Higgs is a pseudo-Goldstone boson (pGB) associated with the global symmetry breaking pattern SU(4) to Sp(4). This particular breaking pattern is interesting, because depending on the embedding of the electroweak (EW) symmetry, the breaking of the global symmetry can either leave the full EW sector intact, break the EW completely to electromagnetism, or more interestingly lead to something between these two extreme cases. In the unbroken case, the entire Higgs doublet can be identified with four of the five Goldstone bosons of the global symmetry breaking.

All of the different alignments of the EW symmetry are equivalent at the tree-level, but since the gauging of the electroweak sector and introducing Yukawa terms for the SM fermions break the global symmetry of the scalar sector, quantum effects determine a preferred vacuum alignment.

In this talk, I will present the main results of our study and show that very slightly broken EW symmetry is preferred. Therefore, the observed Higgs boson is dominantly a pGB, and interestingly the electroweak scale emerges due to the alignment of the EW sector in the global symmetry, whereas the fundamental scale of the spontaneous symmetry breaking is significantly higher.

Visitors
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A. Cabo 2.10. – 27.10. (AT)

HIP NEWS October 5th 2015
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HIP Staff News
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Professor Paula Eerola has been appointed
as the Director of HIP for the 5-year period
starting 1.1.2016.

DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS
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Tuesday 6 October 2015 at 10.15 in A315
Jarno Rantaharju (Odense)
Lattice Four-Fermion Interactions for Beyond Standard Model Physics

Abstract: We present a study of a lattice model of chirally symmetric four-fermion interactions, the Nambu Jona-Lasinio model, with Wilson fermions. Four fermion operators are a necessary part of many models of beyond Standard Model physics. In particular we are interested in technicolor models, where effective four-fermion operators are used to generate the standard model fermion masses. In the ideal walking scenario, the same interaction is responsible for breaking the chiral symmetry in an otherwise conformal model. As a first step, we study the restoration and spontaneous breaking of chiral symmetry in the lattice NJL model before adding a gauge interaction. We map the phase structure of the model and establish chiral symmetry breaking.

Seminar: The Brilliance of Science – the Role of Women in International Science
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Time: Tuesday 6 October, 2015 at 17:00 – 19:30 (note the changed start time)
Organizers:
Finnish Academy of Science and Letters
Embassy of Italy in Helsinki
Istituto Italiano di Cultura
Place: Kumpula Campus, Exactum, Lars Ahlfors Auditorium
Gustaf Hällströmin katu 2 B, 1st floor, Helsinki
Program: http://www.acadsci.fi/tilaisuudet/brilliance.htm

TEDxCERN@University of Helsinki, Friday 9 October webcast at Kumpula
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The webcast is shown in Physicum E207 from 15 to 21. For more information on the event and the speakers, visit: tedxcern.web.cern.ch/speakers.

OPEN POSITIONS:
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A tenure-track faculty opening in Theoretical Particle-Astrophysics at the Department of Physics at Washington University in St. Louis, by Dec. 1st, 2015.
http://www.physics.wustl.edu/faculty_openings

Visitors
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A. Cabo 2.10. – 27.10. (AT)
J. Rantaharju 5.10. – 9.10. (KR)