from September 29, 2015 to October 2, 2015
DESY Hamburg
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Cosmology & Astroparticle Physics


Location: DESY Hamburg
Address: Notkestrasse 85, 22607 Hamburg
Room: Serminar rooms
Date: from 30 Sep 14:00 to 1 Oct 17:55

Timetable | Contribution List

Displaying 28 contributions out of 28
A simple TeV scale model for baryon and lepton number violation is presented, where neutrino mass arises via a one loop radiative seesaw effect and B-violation obeys \Delta B = 2 selection rule, leading to observable neutron-antineutron oscillations. The stability of proton is connected to the neutrino mass generation. Matter-antimatter asymmetry is generated in this model via resonant baryogenesi ... More
Presented by Dr. Bhupal DEV on 1/10/2015 at 14:45
We propose a new method that allows to place an upper limit on the dark matter elastic scattering cross section with nucleons which is independent of the velocity distribution. Our approach combines null results from direct detection experiments with indirect searches at neutrino telescopes, and goes beyond previous attempts to remove astrophysical uncertainties in that it directly constrains the ... More
Presented by Mr. Sebastian WILD on 30/9/2015 at 12:15
We investigate the Affleck-Dine baryogenesis after D-term inflation with a positive Hubble-induced mass term for a B-L flat direction. It stays at a large field value during D-term inflation, and just after inflation ends it starts to oscillate around the origin of the potential due to the positive Hubble-induced mass term. The phase direction is kicked by higher-dimensional Kahler potentials to ... More
Presented by Mr. Masaki YAMADA on 1/10/2015 at 15:15
One aim of cosmic ray measurements is to search for possible signatures of annihilating or decaying dark matter. The excess of positrons measured at the top of the atmosphere has attracted a lot of attention in this context. On the other hand it has been proposed that the data might challenge the established diffusion model for cosmic ray propagation. We investigate variations in the diffusion mod ... More
Presented by Ms. Annika REINERT on 30/9/2015 at 15:05
Session: Cosmology & Astroparticle Physics
Track: Cosmology & Astroparticle Physics
We show that the event excess observed by the IceCube collaboration at TeV–PeV energies, usually interpreted as evidence for astrophysical neutrinos, can be explained alternatively by the scattering of highly boosted dark matter particles. Specifically, we consider a scenario where a ~ 4 PeV scalar dark matter particle φ can decay to a much lighter dark fermion χ, which in turn scatters off nu ... More
Presented by Dr. Xiaoping WANG on 30/9/2015 at 14:50
Session: Cosmology & Astroparticle Physics
Track: Cosmology & Astroparticle Physics
We show that dark matter abundance and the 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 reminiscent to the mod ... More
Presented by Mr. Tommi TENKANEN on 1/10/2015 at 17:35
The next-to-minimal supersymmetric standard model (NMSSM) is a possible extension of the minimal supersymmetric standard model (MSSM) that introduces an additional gauge singlet superfield to solve the mu-problem of the MSSM. In this model there exists a discrete Z_3 symmetry, which can be spontaneously broken in the early universe leading to the formation of domain walls. In this work, we investi ... More
Presented by Mr. Ken'ichi SAIKAWA on 1/10/2015 at 17:05
While dark matter self-interactions may solve several problems with structure formation, so far only the effects of two-body scatterings of dark matter particles have been considered. We show that, if a subdominant component of dark matter is charged under an unbroken U(1) gauge group, collective dark plasma effects need to be taken into account to understand its dynamics. Plasma instabilities can ... More
Presented by Dr. Christian SPETHMANN on 30/9/2015 at 12:45
Session: Cosmology & Astroparticle Physics
Track: Cosmology & Astroparticle Physics
Recently, a new class of models beyond the standard model was proposed wherein the baryonic and leptonic currents separately source U(1) gauge fields. In this talk, I describe the two most minimal viable models known. In these models, the requirement of anomaly cancellation conditions automatically imply the existence of a stable Fermionic dark matter candidate. In addition to dark matter phen ... More
Presented by Dr. Hiren PATEL on 30/9/2015 at 14:20
We consider scenarios where the dark matter becomes unstable due to a non-minimal coupling to gravity. We show that the dark matter can decay into Standard Model particles with a lifetime which is potentially accessible to gamma-ray or neutrino telescopes. We determine the decay branching fractions in some simple scenarios and we set limits on the size of the dark matter non-minimal coupling param ... More
Presented by Sebastian INGENHÜTT on 30/9/2015 at 15:35
I will present a new model of dark matter where the candidate arises from a fermionic 10 representation of SO(10) Grand unified theory. Stability follows from the gauge structure itself, and the low energy dark matter phenomenology is that of a TeV-scale left-right model augmented by a fermion bi-doublet.
Presented by Mr. Sofiane BOUCENNA on 30/9/2015 at 14:35
The Peccei-Quinn (PQ) mechanism provides an elegant solution to the strong CP problem. However astrophysical constraints on axions require the PQ breaking scale to be far higher than the electroweak scale. In supersymmetric models the PQ symmetry can be broken at an acceptable scale if the effective potential for the pseudo-modulus in the axion multiplet develops a minimum at large enough field va ... More
Presented by Mr. Toby OPFERKUCH on 1/10/2015 at 14:05
Session: Cosmology & Astroparticle Physics
Track: Cosmology & Astroparticle Physics
I discuss the scenario of a dark U(1) or SU(N) gauge group coupled to the Standard Model via the Higgs portal. It turns out that minimal CP-conserving hidden Higgs sectors entail stable massive gauge fields which fall into the WIMP category of dark matter candidates. For SU(N), N>2, DM consists of three components, two of which are degenerate in mass. In all of the cases, there are substantial reg ... More
Presented by Dr. Christian GROSS on 30/9/2015 at 13:30
Session: Cosmology & Astroparticle Physics
Track: Cosmology & Astroparticle Physics
The detection of gamma lines from dark matter annihilation has been seen as a "smoking gun" signature for the existence of dark matter. However, it turns out that this signature if far from being a generic feature of dark matter models. In fact in most models tree level annihilation to Standard Model particles and Final State Radiation off them leads to a gamma ray continuum which makes the line ... More
Presented by Dr. Juri SMIRNOV on 30/9/2015 at 15:20
In the early Universe, any particle carrying a conserved quantum number and in chemical equilibrium with the thermal bath will unavoidably inherit a particle-antiparticle asymmetry. A new particle of this type, if stable, would represent a candidate for asymmetric dark matter (DM) with an asymmetry directly related to the baryon asymmetry. We study this possibility for a minimal DM sector constitu ... More
Presented by Dr. Martin KRAUSS on 30/9/2015 at 13:15
I will discuss that for Dirac neutrinos there could, in addition to the standard thermal cosmic neutrino background (CνB), also exist a non–thermal neutrino background with comparable number density. Today's relic density of the non–thermal background can be as large as 0.5*n_gamma. It is constrained by the observational limits on the effective number of massless degrees of freedoms, N_eff ... More
Presented by Mr. Andreas TRAUTNER on 1/10/2015 at 12:30
We derive a non-perturbative equation for the large scale structure power spectrum of long-wavelength modes. We use an operator product expansion together with relations between the three-point function and power spectrum in the soft limit. The resulting equation encodes the coupling to ultraviolet (UV) modes in two time-dependent coefficients, which may be obtained from response functions to (an ... More
Presented by Laura SAGUNSKI on 1/10/2015 at 16:50
Susceptibilities of conserved charges such as baryon minus lepton number enter baryogenesis computations, since they provide the relationship between conserved charges and chemical potentials. Their next-to-leading order corrections are of order $ g $, where $ g $ is a generic Standard Model coupling. They are due to soft Higgs boson exchange, and have been calculated recently, together w ... More
Presented by Mr. Marc SANGEL on 1/10/2015 at 15:00
In composite Higgs scenario, interactions to generate the top Yukawa coupling provide the Higgs potential due to the explicit breaking of a global symmetry. However, such a scenario generically requires a little cancellation in the leading contribution in order to achieve the correct electroweak symmetry breaking with VEV = 246 GeV. We, instead, consider the possibility that the dark matter (DM) s ... More
Presented by Dr. Masaki ASANO on 30/9/2015 at 14:05
We will discuss the relic density of TeV-scale wino-like neutralino dark matter in the pMSSM. We have recently developed a framework enabling us to compute the Sommerfeld enhanced relic density in general pMSSM scenarios. We will present the results of a thorough investigation of certain regions of parameter space, focusing in particular on departures from the well known pure wino scenario: nam ... More
Presented by Mr. Francesco DIGHERA on 30/9/2015 at 12:00
By considering a Quantum Field Theory with time-dependent backgrounds the time-translational symmetry of the Lagrangian may be broken. In my talk I would like to discuss renormalization in curved spacetime using the CTP formalism. In particular, I will show the results for simple diagrams, where explicit calculations are still possible. Connections with the renormalization as an extension of distr ... More
Presented by Mr. Simone DRESTI on 1/10/2015 at 17:20
We consider a fermionic dark matter candidate interacting via a scalar mediator coupled with the Standard Model through a Higgs portal. Motivated by the core-cusp problem, we study dark matter self-interactions which lead us to the region of the parameter space where the scalar mediator is light. We illustrate the relevant features for dark matter abundance, direct search limits and collider const ... More
Presented by Mr. Ville VASKONEN on 30/9/2015 at 13:00
Sterile neutrinos in the keV range are among the most promising candidates for dark matter. We investigate in detail a model that extends the Standard Model by a scalar singlet S and sterile neutrinos N_i. The scalar couples to the Standard Model via a Higgs portal coupling, the size of which determines whether or not the scalar singlet S enters thermal equilibrium in the early Universe. Ste ... More
Presented by Mr. Maximilian TOTZAUER on 1/10/2015 at 14:15
The nuMSM is the Standard Model extended by three right-handed neutrinos with Majorana masses below the electroweak scale. The lightest of them is a candidate of dark matter, which is known as sterile neutrino dark matter. Other two heavier particles with quasi-degenerate masses of O(1) GeV are responsible to explain the masses of ordinary neutrinos and baryon asymmetry of the universe (BAU). I ... More
Presented by Dr. Shintaro EIJIMA on 1/10/2015 at 13:30
Session: Cosmology & Astroparticle Physics
Track: Cosmology & Astroparticle Physics
I present rigorous calculations of the constraints that perturbativity and unitarity apply to dark matter in the well-known portal scenarios. These provide the most stringent upper limit on dark matter mass in the thermal cosmology. I will also discuss the physics of dark matter bound states that can become important when the interactions of dark matter become so strong.
Presented by Dr. William SHEPHERD on 30/9/2015 at 12:30
I will discuss the idea to combine singlet inflation and Higgs Portal Dark Matter in such a way that the same particle (a gauge singlet scalar) first drives inflation and later freezes out to become cold dark matter. Considering the implications of the Higgs discovery, limits from LUX and observations by Planck, I will show that large regions of parameter space remain viable but will be fully expl ... More
Presented by Dr. Felix KAHLHOEFER on 1/10/2015 at 16:35
Both WMAP and PLANCK have hinted at a slight suppression of power in the CMB temperature spectrum at large angular scales. Yet this power loss is usually unaccounted for by models that are claimed to provide a best fit to the data at first order, such as the Starobinsky f(R) model. In a first step, we demonstrate how to obtain a viable observational signature in f(R) theory by explicitly construct ... More
Presented by Mr. Benedict BROY on 1/10/2015 at 16:20
Session: Cosmology & Astroparticle Physics
Track: Cosmology & Astroparticle Physics
Apart from naturally explaining their smallness, models in which neutrino masses are generated only at the loop level are particularly interesting as they often contain electrically charged scalar fields. These additional particles contribute in particular to lepton flavour and/or number violating processes, like mu -> e gamma or neutrinoless double beta decay. On the other hand, at LHC new charge ... More
Presented by Tanja GEIB on 1/10/2015 at 12:00
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