Browsing by Author "Moretti, Stefano"

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Naturalness and dark matter in the supersymmetric B - L extension of the standard model
(Amer Phyical, 2017-09-06) Delle, Rose Luigi; Khalil, Shaaban; King, Simon J. D.; Marzo, Carlo; Moretti, Stefano; Ün, Cem Salih; Uludağ Üniversitesi/Fen Edebiyet Fakültesi/Fizik Bölümü.; 0000-0002-0595-8803; N-3421-2014; 55325758100
We study the naturalness properties of the B - L supersymmetric standard model (BLSSM) with type-I seesaw and compare them to those of the minimal supersymmetric standard model (MSSM) at both low (i.e., Large Hadron Collider) energies and high (i.e., unification) scales. By adopting standard measures of naturalness, we assess that, in the presence of full unification of the additional gauge couplings and scalar/fermionic masses of the BLSSM, such a scenario reveals a somewhat higher degree of fine-tuning (FT) than the MSSM, when the latter is computed at the unification scale and all available theoretical and experimental constraints, but the dark matter (DM) ones, are taken into account. Yet, such a difference, driven primarily by the collider limits requiring a high mass for the gauge boson associated to the breaking of the additional U(1)(B-L) gauge group of the BLSSM in addition to the SU(3)(C) x SU(2)(L) x U(1)(Y) of the MSSM, should be regarded as a modest price to pay for the former in relation to the latter, if one notices that the nonminimal scenario offers a significant volume of parameter space where numerous DM solutions of different compositions can be found to the relic density constraints, unlike the case of the minimal structure, wherein only one type of solution is accessible over an ever diminishing parameter space. In fact, this different level of tension within the two SUSY models in complying with current data is well revealed when the FT measure is recomputed in terms of the low-energy spectra of the two models, over their allowed regions of parameter space now in the presence of all DM bounds, as it is shown that the tendency is now opposite, with the BLSSM appearing more natural than the MSSM.
Phenomenology of 2HDM with vectorlike quarks
(Amer Phyical Soc, 2018-05-15) Arhrib, Abdesslam; Benbrik, Rachid; King, Simon J.D.; Manaut, B.; Moretti, Stefano; Ün, Cem Salih; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0002-0595-8803; N-3421-2014; 55325758100
In this paper, we examine the consistency of the Large Hadron Collider (LHC) data collected during Runs 1 and 2 by the ATLAS and CMS experiments with the predictions of a 2-Higgs doublet model embedding vectorlike quarks (VLQs) for pp -> H, A production and H, A -> gamma gamma decay mechanisms, respectively, of (nearly) degenerate CP even (H) and CP-odd (A) Higgs bosons. We show that a scenario containing one single VLQ with electromagnetic charge 2/3 can explain the above ATLAS and CMS data for masses in the region 350 GeV <= m(VLQ )<= 1.5 TeV or so, depending on tan beta, and for several values of the mixing angle between the top quark (t) and its VLQ counterpart (T). We then perform a global fit onto the model by including all relevant experimental as well as theoretical constraints. The surviving samples of our analysis are discussed within 2 sigma of the LHC measurements. Additionally, we also comment on the recent anomalous result reported by CMS using Run 2 data on the associated Standard Model Higgs boson production with top quark pairs pp -> t(t)over-barh with an observed significance of 3.3 sigma. Other than these specific examples, we also present a phenomenological analysis of the main features of the model, including the most promising T decay channels.
Prospects for sneutrino dark matter in the blssm
(Soc Italiana Fisica, 2018-07-01) King, Simon J. D.; Delle Rose, Luigi; Khalil, Shaaban; Kulkarni, Suchita; Marzo, Carlo; Moretti, Stefano; Ün, Cem Salih; ÜN, CEM SALİH; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Fizik Anabilim Dalı.; N-3421-2014
The (B - L) Supersymmetric Standard Model (BLSSM) motivates several Dark Matter (DM) candidates beyond the Minimally Supersymmetric Standard Model (MSSM). We assess the comparative naturalness of the two models and discuss the potential detection properties of a particular candidate, the Right-Handed (RH) sneutrino.