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Exploring the Dark Sector
 
1503 Conference Room, 5th fl., KIAS
March 16 (Mon) – March 20 (Fri), 2015
Program Home > Program
 
 


Exploring the Dark Sector Titles and Abstracts

 


3/16 (Mon)
 
Yannis Semertzidis(IBS-CAPP) “The axion dark matter research plan at CAPP” 
  Axions are the result of the dynamic mechanism invented to solve the strong CP-problem. For a certain mass range they can also become the dark matter of our universe. Assuming that they are the dark matter, one can look for them by converting their vacuum field into oscillating electric fields. We will present the status of the research plan at CAPP towards achieving enough sensitivity to detect the axions even if they are only 10% of the total dark matter in our galaxy
 
Fuminobu Takahashi(Tohoku) “Dark radiation”
   I will review some of dark radiation models proposed so far, and discuss the implications of the current constraints and future prospects
 
 
 
Kai Schmitz(IPMU) “Stabilizing the Axion by Strong Dynamics”
  The proximity of the Peccei-Quinn (PQ) scale to the scale of SUSY breaking in models of pure gravity mediation hints at a common dynamical origin of these two scales. In this talk, I will present a minimal scenario that demonstrates how such a connection could be made manifest. In particular, I focus on the implementation of the PQ mechanism into models of dynamical SUSY breaking, so that both the SUSY breaking scale and the PQ scale end up being generated via dimensional transmutation. Moreover, I rely on the anomaly-free discrete Z_4^R symmetry required in models of pure gravity mediation to solve the mu problem to protect the PQ symmetry from the dangerous effect of higher-dimensional operators. This results in a rich phenomenology featuring a QCD axion with a decay constant of O(10^10)  GeV and mixed WIMP/axion dark matter, the characteristics of which I will briefly outline

Chaehyun Yu(Academia Sinica)   “Dark matter search at B factories”
 
   The lightest Kaluza-Klein excitation of neutral electroweak gauge bosons is a stable weakly interacting massive particle and could serve as a natural dark matter candidate when Kaluza-Klein parity is conserved. We examine concrete model realization of such dark matter in the context of non-minimal universal extra dimension. The boundary localized kinetic terms for the electroweak gauge bosons are allowed, that leads non-trivial mixings among Kaluza-Klein gauge bosons thus controls the properties of electroweak Kaluza-Klein dark matter. We also provide detailed studies on electroweak precision measurements, direct and indirect detections of dark matter particles and collider experiments at the LHC

 
3/17(Tue)
 
   Dark matter annihilation during the cosmic dark ages can heat and ionize the universe, screening the cosmic microwave background and modifying its anisotropies. I will discuss the latest constraints on dark matter from measurements of the CMB, and state-of-the-art methods for probing energy injection during the cosmic dark ages
 
 
Wan il Park(Valencia) “Phenomenology of dark matter charged under a hidden local symmetry”
   I will introduce a couple of dark matter (DM) models in which DM is stabilized by a local symmetry of Hidden sector, and discuss briefly DM phenomenology of those models
 
   In the SO(5)xU(1) gauge-Higgs unification (GHU), a set of SO(5)-spinorial fermions are introduced.
These fermions do not mix with SM fermions and their fermion numbers are conserved. Among them, the lightest neutral ones can be WIMP dark matter and we will refer them as “Dark Fermions”.
   In this talk we discuss the relic density and direct detection of such fermions.
The relic density of DF depends on the number of flavor of DF, nF, and the warp factor zL.
We found that when all DF are degenerated and nF=3, the relic density can be smaller than the current experimental value. When DFs are separated to 1 light and 3 heavy DFs, we found that there is a parameter region in which the DF relic density satisfies the experimental bound, and DFs can be found in direct detection searches in the current and future experiments. This talk is based on the paper arXiv:1407.3424 (published in PTEP)
 
Takashi Toma(LPT Orsay) “Higher Multiplet Dark Matter”
   We consider SU(2)L higher multiplet dark matter stabilized by accidental symmetry. This kind of dark matter has characteristic features for detections. In the minimal scenario, dark matter mass should be more than 10 TeV due to large gauge coupling of dark matter and large annihilation cross section. We explore possibilities of lighter dark matter mass
 
   Collider experiments are one of the most promising ways to constrain dark matter interactions. To study several types of DM-SM couplings, however, it is necessary to consider simplified models with light mediators. In this talk, I will discuss the first simplified model study of the magnetic dipole interacting dark matter (MiDM) by including the one-loop momentum dependent form factors -- given by the Dark Penguins -- in the collider processes. Under the assumption of anarchic flavor structure in the dark sector, we can constrain the DM-mediator couplings from the monojet, monophoton, and diphoton searches at colliders and compare the results to the direct and indirect detection experiments. When dark penguins have an almost aligned flavor structure with the DM mass, searches of non-pointing photon signals can set interesting constraints to the model
 
Beranger Dumont(CTPU-IBS) “Constraints on the Inert Doublet Model from Run I of the LHC”
   The ATLAS and CMS collaborations have performed a large number of searches for new physics during Run I of the LHC, targeting in particular final states with missing transverse energy. The implications of these negative results for new physics go well beyond the interpretations given in the experimental papers. Separate, validated implementations of the analyses using public fast simulation tools are necessary for theorists to fully exploit the potential of these searches. I will present MadAnalysis 5, the framework we use to constrain generic BSM physics, and the public database of LHC analyses we have initiated. Using two analyses from the database, a Higgs search and a SUSY search targeting final states with two leptons and missing transverse energy, we put constraints on the Inert Doublet Model and discuss the interplay with other constraints

Chengcheng han(APCTP) “Probing the higgsinos at the LHC”


 3/18(Wed)
 
Seonho Choi(SNU) "Overview on DM direct detection"
 
   Dark matter constitutes about five sixth of the total matter in the observable Universe, and forms large spheroidal halos hosting the majority of the visible astrophysical structures. Yet, the particles forming the Milky Way dark matter halo have so far escaped detection, and the dark matter particle mass and interactions remain unknown. The detection of dark matter particles in the solar neighborhood through their scattering off nuclei of a terrestrial detector is the goal of the so-called dark matter direct detection technique. In my talk, I will review the status and illustrate the prospects of this rapidly evolving research area, with a focus on theoretical advances which have recently been made in the field
 
   Located in Laboratori Nazionali del Gran Sasso, Italy, the XENON experiment is one of the most sensitive direct dark matter search experiments in the world. This talk will give an overview of the XENON project, its goals and the experimental methods employed. The main focus will lay on the XENON100 experiment. The results it has produced thus far will be presented and compared to other dark matter experiments. The talk will close out with an outlook into the future by presenting XENON1T, the next generation dark matter detector which is currently under construction

 
   As it is well known, direct detection experiments are already highly sensitive to dark matter particles coupling to the first-generation quarks, the Higgs or the Z boson. However, there are scenarios in which the dark matter particle does not couple to nucleons at tree-level, and correspondingly a signal in direct detection experiments can only arise from loop diagrams. One simple example is singlet Dirac dark matter coupling to a Standard Model lepton or heavy quark via a charged scalar mediator. In this talk, we present the results of an extensive study of the direct detection phenomenology of this model, showing that despite the loop-suppressed coupling of dark matter to nucleons, LUX is already able to rule out significant parts of the thermal parameter space. Moreover, we find that future direct detection experiments will have excellent prospects to close in completely on these scenarios, even for dark matter masses well above 1 TeV
 
 
   Dark Matter could be detected through neutrino signal from self-annihilating dark matter captured in the Sun. New detection channels offer interested prospects at current and next generation neutrino detectors. The talk will review current result and potential with future detectors
 
   We explore detection prospects of a non-standard dark sector in the context of boosted dark matter. When a DM annihilation or decay process yields additional dark matter particles in the final state, these final state dark matter particles gain a large Lorentz boost factor. Neutrino telescopes offer a promising detection channel for boosted dark matter, as boosted dark matter particles can scatter off electrons above the Cherenkov threshold
 
   The observed events by IceCube, notably the PeV cascades accompanied by events at lower energies (30−400) TeV, are clearly in excess over atmospheric background fluxes and beg for an astroparticle physics explanation. I will discuss the possibility to interpret the IceCube data by PeV mass scale decaying Dark Matter. I discuss generic signatures of this scenario, including its energy spectrum distortion with respect to the benchmark expectation for astrophysical sources, as well as peculiar anisotropies. A direct comparison with the data show a good match with the above-mentioned features. I further discuss possible future checks of this scenario

 
3/19(Thu)
 
 
   The possible gamma-ray excess in the inner Galaxy and the Galactic center suggested by Fermi-LAT observations has triggered great interest in the community. Among its various interpretations have been WIMP dark matter annihilations, gamma-ray emission from a population of millisecond pulsars, or emission from cosmic rays injected in a sequence of burst-like events or continuously at the GC. Given that the galactic diffuse emission is the dominant (by an order of magnitude or more) at any direction greater than 2 degrees from the GC understanding the background systematics has been a vital missing piece in the discussion. I will present the first comprehensive study of model systematics coming from the Galactic diffuse emission in the inner part of our Galaxy and their impact on the inferred properties of the excess emission at Galactic latitudes between 2 and 20 degrees and energies 300 MeV to 500 GeV. I will show both theoretical and empirical model systematics, which are deduced from a large range of Galactic diffuse emission models and a principal component analysis of residuals in numerous test regions along the Galactic plane. The hypothesis of an extended spherical excess emission with a uniform energy spectrum is compatible with the Fermi-LAT data. Assuming that this excess is the extended counterpart of the one seen in the inner few degrees of the Galaxy, a lower limit of 10 degrees (95% CL) can be derived on its extension away from the GC. In light of the large correlated uncertainties that affect the subtraction of the Galactic diffuse emission in the relevant regions, the energy spectrum of the excess is equally compatible with both a simple broken power-law of break energy 2.1 $pm$ 0.2 and with spectra predicted by the self-annihilation of dark matter, implying in the case of $bar{b}b$ final states a dark matter mass of 49$^{+6.4}_{-5.4}$ GeV
 
   An unbroken $Z_3$ symmetry remains when local $SU(2)_X$ is broken spontaneously by one quadruplet. The gauge boson $chi_mu (bar chi_mu )$ carries the dark charge and is the candidate of dark matter (DM). By the mixture of scalar boson $phi_r$ of quadruplet and standard model (SM) Higgs, the DM can annihilate to SM particles through Higgs portal. For investigating the implications of vector DM, we study the relic density of DM, the direct detection of DM-nucleon scattering and the excess of gamma-ray spectrum, which is supported by the data from {it Fermi} Gamma-Ray Space Telescope. We find that with the DM mass of around $70$ GeV in our model, the excess of gamma-ray could be fitted well with the data
 
   A sharp spectral feature in the gamma-ray sky would be a "smoking gun" for dark matter annihilations.
In this work we focus on box-shaped gamma-ray spectral features, that can arise in models where the dark matter annihilates into intermediate scalars that then decay into a pair of photons.
   This kind of signal can be severely constrained by the future Cherenkov Telescope Array. Using detailed information on the instrument such as the effective area and the energy resolution, we derive projected limits on box-shaped gamma-ray features for heavy dark matter particles, a mass range that is not accessible by any other detection method. Our region of interest is a 2° x 2° region around the Galactic Center, a prime target for dark matter annihilations due to its large dark matter density. The robustness of our approach is tested by varying the size and location of the energy windows within the sliding energy window technique for narrow and wide boxes. We conclude by discussing the relevance of our constraints for particular particle physics models featuring gamma-ray boxes
 
   Recently observed gamma-ray excess in GeV ranges suggests that light dark matter particles may annihilate into the standard model fermions. In this work, we study Z' mediated charged dark matter model with the gauged U(1)_(L(mu)-L(tau)) gauge group, and identify the allowed region from thermal relic density in the Universe. We also discuss direct detection and the LHC signatures
 
   We explore the explanation of the Fermi Galactic Center Excess (GCE) in the Next-to-Minimal Supersymmetric Standard Model (NMSSM). We systematically consider various experimental constraints including the Dark Matter (DM) relic density, DM direct detection results and indirect searches from dwarf galaxies. We find that, for DM with mass ranging from 30 to 40 GeV, the GCE can be explained by the annihilation $chi chi to a^ast to b bar{b}$ only when the CP-odd scalar satisfies $m_a simeq 2 m_chi$, and in order to obtain the measured DM relic density, a sizable $Z$-mediated contribution to DM annihilation must intervene in the early universe. As a result, the higgsino mass $mu$ is upper bounded by about 350 GeV. Detailed Monte Carlo simulations on the $3ell+ E_T^{miss}$ signal from neutralino/chargino associated production at 14-TeV LHC indicate that the explanation can be mostly (completely) excluded at $95%$ C.L. with an integrated luminosity of 100(200) fb$^{-1}$. We also discuss the implication of possible large $Z$ coupling to DM for the DM-nucleon spin dependent (SD) scattering cross section, and find that although the current experimental bounds on $sigma^{rm SD}_p$ is less stringent than the spin independent (SI) results, the future XENON-1T and LZ data may be capable of testing most parts of the GCE-favored parameter region
 
 
I will present some results from an ongoing analysis of the neutralino dark matter with a large singlino fraction in the next-to-minimal supersymmetric Standard Model (NMSSM). Such neutralinos can yield the correct dark matter relic density in mass regions that are not obtainable in the MSSM. In particular lighter masses between 60 GeV and 100 GeV and heavier masses between 600 GeV and 1 TeV are possible, where the neutralino is either singlino-dominated or singlino–higgsino-dominated. I will consider the prospects for discovery or exclusion of such dark matter at the IceCube neutrino observatory and also the affects of the proposed PINGU extension on the experimental sensitivity
 

3/20(Fri)
 
P.J. Fox(Fermi Lab) “Dark Matter at colliders”
 
Asymmetric dark matter is motivated by the observed fact that the ordinary and dark matter mass densities are quite similar. The general structure and phenomenology of such theories will be reviewed
 
 
 
Zhaofeng Kang(KIAS) "Quark-phobic Dark Matter"
 
 
It is an interesting possibility that dark matter interacts the SM particles only through the Higgs portal. If we consider a QCD-like strong interaction in the hidden sector, the pseudo Nambu-Goldstone bosons resulting from the spontaneous chiral symmetry breaking are the lightest hadrons in the hidden sector and thus can be the dark matter. We shall call this dark matter candidates the dark pions. In this talk, we will show that the portal interaction between the Higgs and the dark pions is related to the scalar form factor of the dark pion and the enhancement effects of the portal interaction by this form factor tend to relax the constraint on the dark matter mass