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Kfir Blum

Publications and source records attributed to Kfir Blum.

59 records · Page 4Linked to original sources
arXiv2009

BMSSM Implications for Cosmology

The addition of non-renormalizable terms involving the Higgs fields to the MSSM (BMSSM) ameliorates the little hierarchy problem of the MSSM. We analyze in detail the two main cosmological issues affected by the BMSSM: dark matter and baryogenesis. The regions for which the relic abundance of the LSP is consistent with WMAP and collider constraints are identified, showing that the bulk region and other previously excluded regions are now permitted. Requiring vacuum stability limits the allowed regions. Based on a two-loop finite temperature effective potential analysis, we show that the electroweak phase transition can be sufficiently first order in regions that for the MSSM are incompatible with the LEP Higgs mass bound, including parameter values of \tanβ\lsim 5, m_{\tilde{t}_{1}} > m_t, m_Q << TeV.

hep-ph↗
arXiv2009

Vacuum (Meta)Stability Beyond the MSSM

We study the stability of the Higgs potential in the framework of the effective Lagrangian beyond the MSSM. While the leading nonrenormalizable operators can shift the Higgs boson mass above the experimental bound, they also tend to render the scalar potential unbounded from below. The destabilization is correlated with the Higgs mass increase, so that if quantum corrections are small the problem is severe. We show that a supersymmetric sub-leading correction stabilizes the potential within the domain of validity of the effective theory. Constraints on MSSM parameters as well as on higher dimensional operators are derived, ensuring that our vacuum has a lifetime longer than the present age of the universe. In addition we show that when effective operators are responsible for evading the LEP bound, stability constraints imply an upper bound on the scale of new physics in the few TeV range.

hep-ph↗
arXiv2008

Beyond MSSM Baryogenesis

Taking the MSSM as an effective low-energy theory, with a cut-off scale of a few TeV, can make significant modifications to the predictions concerning the Higgs and stop sectors. We investigate the consequences of such a scenario for electroweak baryogenesis. We find that the window for MSSM baryogenesis is extended and, most important, can be made significantly more natural. Specifically, it is possible to have one stop lighter than the top and the other significantly lighter than TeV simultaneously with the Higgs mass above the LEP bound. In addition, various aspects concerning CP violation are affected. Most notably, it is possible to have dynamical phases in the bubble walls at tree level, providing CP violating sources for Standard Model fermions.

hep-ph↗
arXiv2007

Probing CP violation in neutrino oscillations with neutrino telescopes

Measurements of flavor ratios of astrophysical neutrino fluxes are sensitive to the two yet unknown mixing parameters $θ_{13}$ and $δ$ through the combination $\sinθ_{13}\cosδ$. We extend previous studies by considering the possibility that neutrino fluxes from more than a single type of sources will be measured. We point out that, if reactor experiments establish a lower bound on $θ_{13}$, then neutrino telescopes might establish an upper bound on $|\cosδ|$ that is smaller than one, and by that prove that CP is violated in neutrino oscillations. Such a measurement requires several favorable ingredients to occur: (i) $θ_{13}$ is not far below the present upper bound; (ii) The uncertainties in $θ_{12}$ and $θ_{23}$ are reduced by a factor of about two; (iii) Neutrino fluxes from muon-damped sources are identified, and their flavor ratios measured with accuracy of order 10% or better. For the last condition to be achieved with the planned km^3 detectors, the neutrino flux should be close to the Waxman-Bahcall bound. It motivates neutrino telescopes that are effectively about 10 times larger than IceCube for energies of O(100 TeV), even at the expense of a higher energy threshold.

hep-ph↗