We analyze the stability of four-dimensional de Sitter vacua constructed by compactifying massive Type IIA supergravity in the presence of two O8 sources [1]. When embedded in String Theory the first source has a clear interpretation as an O8− plane, but the second one could correspond to either an O8+ plane or to an O8− plane with 16 D8-branes on top. We find that this latter solution has a tachyonic instability, corresponding to the D8 branes moving away from the O8 −  plane. We comment on the possible ways of distinguishing between these sources.

France

Iosif Bena

United States

G. Luca

Mariana Graña

Sweden

Gabriele Monaco

Oh, wait, O8 de Sitter may be unstable!

We present, how a systematic study of $$B \rightarrow D\ell N$$ <math><mrow><mi>B</mi><mo>→</mo><mi>D</mi><mi>ℓ</mi><mi>N</mi></mrow></math>  ($$D \rightarrow K \ell N$$ <math><mrow><mi>D</mi><mo>→</mo><mi>K</mi><mi>ℓ</mi><mi>N</mi></mrow></math> ) decays with $$\ell =\mu ,\tau $$ <math><mrow><mi>ℓ</mi><mo>=</mo><mi>μ</mi><mo>,</mo><mi>τ</mi></mrow></math> , at Belle II (BESIII) can provide unambiguous signature of a heavy neutrino N and/or constrain its mixing with active neutrinos $$\nu _\ell $$ <math><msub><mi>ν</mi><mi>ℓ</mi></msub></math> , which is parameterized by $$| U_{\ell N} |^2$$ <math><mrow><mrow><mo>|</mo></mrow><msub><mi>U</mi><mrow><mi>ℓ</mi><mi>N</mi></mrow></msub><msup><mrow><mo>|</mo></mrow><mn>2</mn></msup></mrow></math> . Our constraint on $$\vert U_{\mu N} \vert ^2$$ <math><mrow><mrow><mo>|</mo></mrow><msub><mi>U</mi><mrow><mi>μ</mi><mi>N</mi></mrow></msub><msup><mrow><mo>|</mo></mrow><mn>2</mn></msup></mrow></math>  that can be achieved from the full Belle II data is comparable with what can be obtained from the much larger data set of the upgraded LHCb. Additionally, our method offers better constraint on $$\vert U_{\mu N} \vert ^2$$ <math><mrow><mrow><mo>|</mo></mrow><msub><mi>U</mi><mrow><mi>μ</mi><mi>N</mi></mrow></msub><msup><mrow><mo>|</mo></mrow><mn>2</mn></msup></mrow></math>  for mass of sterile neutrino $$m_N &lt; 2$$ <math><mrow><msub><mi>m</mi><mi>N</mi></msub><mo>&lt;</mo><mn>2</mn></mrow></math>  GeV. We can also probe the Dirac and Majorana nature of N by observing the sequential decay of N, including suppression from observation of a displaced vertex as well as helicity flip, for Majorana N.

South Korea

C. Kim

Youngjoon Kwon

Donghun Lee

Sechul Oh

Dibyakrupa Sahoo

Probing sterile neutrinos in B (D) meson decays at Belle II (BESIII)

The universality of the weak interactions can be tested in semileptonic b→c transitions, and in particular in the ratios R(D(*)) ≡ Γ(B→D(*)τν)/Γ(B→D(*)lν) (where l=μ or e). Due to the recent differences between the experimental measurements of these observables by BaBar, Belle and LHCb on the one hand and the Standard Model predicted values on the other hand, we study the predicted ratios R(D(*))=Γ(B→D(*)τ+“missing”)/Γ(B→D(*)lν) in scenarios with an additional sterile heavy neutrino of mass ∼1 GeV. Further, we evaluate the newly defined ratio R(0)≡Γ(B→τ+“missing”)/Γ(B→μν) in such scenarios, in view of the future possibilities of measuring the quantity at Belle-II.

Chile

Gorazd Cvetič

Francis Halzen

C. S. Kim

Anomalies in (semi)-leptonic B decays BÂ±âÏÂ±Î½, BÂ±âDÏÂ±Î½ and BÂ±âD*ÏÂ±Î½, and possible resolution with sterile neutrinoG.C.Â acknowledges the support by FONDECYT (Chile) (1130599), The work of C.S.K. was supported in part by the NRF grant funded by the Korean government of the MEST (2016R1D1A1A02936965)

In the presence of OH impurities in the DAMA crystals, GeV-scale WIMPs elastically scattering off of hydrogen nuclei with a spin independent cross section of ∼10−33cm2 might explain the annual modulation observed by the DAMA experiment, while being consistent with other direct dark matter searches, as scattering would occur at energies below the energy threshold of other detectors. In this work we examine this possibility and show that, independent of the level of OH impurities in the DAMA crystals, for several reasons this scenario does not provide a viable explanation to the DAMA signal.

Stefano Profumo

Farinaldo S. Queiroz

GeV WIMPs scattering off of OH impurities cannot explain the DAMA signal