# DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS

## HIP seminar room A315

**Thursday 16 November at 10.15 in A315: Subhadeep Mondal (Helsinki)**

*The various aspects and future prospects of heavy neutrino search*

Abstract: In this talk I will discuss various phenomenological aspects of heavy neutrinos which are essential to generate light neutrino masses and mixing as observed by the neutrino oscillation experiments. In particular I shall focus on the different seesaw mechanisms both in the context of minimally extended Standard Model and Supersymmetric frameworks. I shall summarize the current experimental results and constraints on such neutrino mass models from direct and indirect search of the heavy neutrinos as well as their discovery prospects at LHC and future collider experiments.**Thursday 23 November at 10.15 in A315: Shao-Jiang Wang (Beijing)**

*The gravitational waves from the first-order phase transition with a dimension-six operator*

Abstract: We investigate in details the gravitational wave (GW) from the first-order phase transition (PT) in the extended standard model of particle physics with a dimension-six operator, which is capable of exhibiting the recently discovered slow first-order PT in addition to the usually studied fast first-order PT. To simplify the discussion, it is sufficient to work with an example of a toy model with the sextic term, and we propose a unified description for both slow and fast first-order PTs. We next study the full one-loop effective potential of the model with fixed/running renormalization-group (RG) scales. Compared to the prediction of GW energy density spectrum from the fixed RG scale, we find that the presence of running RG scale could amplify the peak amplitude by amount of one order of magnitude while shift the peak frequency to the lower frequency regime, and the promising regime of detection within the sensitivity ranges of various space-based GW detectors shrinks down to a lower cut-off value of the sextic term rather than the previous expectation.**Tuesday 28 November at 10.15 in A315: Antti Kupiainen (Helsinki)**

*Proof of the DOZZ Formula*

Abstract: In 1994 Dorn and Otto and in 1996 independently Zamolodchikov and Zamolodchikov proposed a remarkable explicit expression, the so called DOZZ formula for the 3 point structure constants of the Liouville Conformal Field Theory (LCFT). LCFT is a building block of non-critical string theory and two dimensional quantum gravity and the DOZZ formula is the key to its integrability. Remarkably the LCFT strucure constants also give the Nekrason partition functions of four dimensional gauge theories. I will review a rigorous probabilistic construction of LCFT and sketch a proof of the DOZZ formula obtained together with R. Rhodes and V. Vargas.**Thursday 30 November 2017 at 10.15 in A315: Xiaoyong Chu (Vienna)**

*Dark matter indirect signals with a long-lived mediator*

Abstract: In hidden sector models, dark matter particles could annihilate into light and metastable mediators, which subsequently decay far away from where they are produced. I will talk about how the indirect signatures in this scenario are altered with respect to the situation of conventional WIMP, as well as how this scenario may be able to explain the observed PAMELA/AMS-02 positron excess in cosmic rays.**Thursday 14 December 2017 at 10.15 in A315: Stephan Huber (Sussex)**

*TBA*

Abstract: TBA

Hopefully the up to **50 min + 10 min discussion long **seminar/colloquium will be understandable to a wide audience.

Contacts: Keijo Kajantie (keijo kajantie at helsinki fi) [department / HIP seminar],

Francesco Montanari (francesco montanari at helsinki fi) [cosmo seminar]

**Other related seminars**

Friday 10-12 seminar series in D117: Astrophysics seminar.

Mathematical Physics Seminar and Workshop series Wed 14-16 in Exactum C123.