The 28 GeV Dimuon Excess in Lepton Specific 2HDMCici, Ali;Khalil, Shaaban;Nis, Busra;Un, Cem Salih
doi: 10.48550/arXiv.1909.02588pmid: N/A
Abstract: We explore the Higgs mass spectrum in a class of Two Higgs Doublet Models (THDMs) in which a scalar SU(2)_L doublet interacts only with quarks, while the second one interacts only with leptons. The spectrum includes two CP-even Higgs bosons, either of which can account for the SM-like Higgs boson, and the spectra involving light Higgs bosons receive strong impacts from the LEP results and the current collider analyses. We find that a consistent spectrum can involve a CP-odd Higgs boson as light as about 10 GeV, while the lightest CP-even Higgs boson cannot be lighter than about 55 GeV when m_A ~ 28 GeV. These analyses can rather bound the low tan beta region which can also accommodate an observed excess in dimuon events at m_mumu ~ 28 GeV. A lepton-specific class of THDMs (LS-THDM) can predict such an excess through A -> mu mu decays, while the solutions can be constrained by the A -> tau tau mode. After constraining the solutions with the consistent ranges of sigma(pp -> bbA -> bb tau tau), a largest excess at about 1.5 sigma at 8 TeV center of mass (COM) energy and 2 sigma at 13 TeV COM is observed for tan beta ~ 12 and m_A ~ 28 GeV in the sigma(pp -> bbA -> bb mu mu) events.
Higgs-Boson Masses and Mixings in the MSSM with CP Violation and Heavy SUSY ParticlesMurphy, Nick;Rzehak, Heidi
doi: 10.48550/arXiv.1909.00726pmid: N/A
Abstract: We calculate the Higgs-boson mass spectrum and the corresponding mixing of the Higgs states in the Minimal Supersymmetric Standard Model (MSSM). We assume a mass-hierarchy with heavy SUSY particles and light Higgs bosons. To investigate this scenario, we employ an effective-field-theory approach with a low-energy Two-Higgs-Doublet Model (2HDM) where both Higgs doublets couple to up- as well as down-type fermions. We perform a one-loop matching of the MSSM to the 2HDM and evolve the parameters to the low energy scale by exploiting two-loop renormalization group equations, taking the complex parameters into account. For the calculation of the pole mass, we compare three different options: one suitable for large charged Higgs masses, one for low charged Higgs masses, and one approximation that interpolates between these scenarios. The phase dependence of the mass of the lightest neutral Higgs boson can be sizeable, i.e. on the order of a couple of GeV depending on the scenario. In addition, we discuss the CP composition of the neutral Higgs bosons.
Resonance production of keV sterile neutrinos in core-collapse supernovae and lepton number diffusionSyvolap, Vsevolod;Ruchayskiy, Oleg;Boyarsky, Alexey
doi: 10.48550/arXiv.1909.06320pmid: N/A
Abstract: We investigate how hypothetical particles - sterile neutrinos - can be produced in the interior of exploding supernovae via the resonant conversion of $\bar\nu_\mu$ and $\bar \nu_\tau$. The novelty of our treatment lies in the proper account of the resulting lepton number diffusion. We compute the yield of sterile neutrinos and find that even after taking into account back reaction, sterile neutrinos can carry out a sizeable fraction of the total energy of the explosion comparable to that of active neutrinos. The production is, however, exponentially sensitive to the temperature in the inner supernovae regions, making robust predictions of challenging. In order to understand whether this production affects supernova evolution and can therefore be constrained, detailed simulations including the effects of sterile neutrinos are needed.
Lower tensor to scalar ratio in a SUGRA motivated inflationary potentialAdhikari, Rathin;Gangopadhyay, Mayukh R.;Yogesh
doi: 10.1134/S0202289322010029pmid: N/A
Abstract: A scalar potential obtained from the $D$-term in the Supergravity models, which dominates over $F$ term and is mainly responsible for the inflationary phase in the early universe, is studied. The potential with canonical kinetic terms for scalar fields in the Lagrangian, has a very slow roll feature in comparison to various other plateau type inflationary potentials. In this case, a much lower tensor-to-scalar ratio ($r$) of $\mathcal{O}(10^{-3})$ is achievable. The requirement of slow roll condition for the inflation potential implies that the up type neutral scalar and the down type neutral scalar in Supergravity models are with equal field strength at the time of inflation. If this relationship holds down to the electroweak scale for the corresponding $vev$ values of these fields, then it will indicate a higher SUSY breaking scale around 100 TeV. The predicted values of the inflationary observables are well within the 1-$\sigma$ bounds of the recent constraints from {\it Planck'18} observations. The era of reheating after the inflationary phase, is also studied and the bounds on the reheating temperature ($T_{re}$) is calculated for a different equation of states during reheating ($w_{re}$) for the {\it Planck'18} allowed values of the scalar spectral index ($n_s$). For our model with $w_{re}=2/3$ and $w_{re}=1$, after satisfying all the bounds due to gravitino overproduction, we can have big parameter space for $T_{re}$ which is well inside {\it Planck'18} 1-$\sigma$ bound on $n_s$.