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R. Nevzorov

Publications and source records attributed to R. Nevzorov.

At least 55 records · Page 3Linked to original sources
arXiv2011

Theoretical aspects of electroweak symmetry breaking in SUSY models

The electroweak (EW) symmetry breaking in the simplest supersymmetric (SUSY) extensions of the standard model (SM), i.e. minimal and next-to-minimal supersymmetric standard models (MSSM and NMSSM), is considered. The spectrum of the Higgs particles, upper bound on the mass of the lightest Higgs boson and little hierarchy problem are discussed. The breakdown of gauge symmetry and Higgs phenomenology within the E6 inspired SUSY models with extra U(1)' factor are briefly reviewed.

hep-ph↗
arXiv2010

Nonstandard Higgs decays in the E(6)SSM

We study the nonstandard decays of the lightest Higgs state within the Exceptional Supersymmetric Standard Model (E6SSM). We argued that the SM--like Higgs boson can decay predominantly into dark matter particles while its branching ratios into SM particles varies from 2% to 4%. This scenario also implies the presence of other relatively light Inert chargino and neutralino states in the particle spectrum with masses below 200 GeV. We argue that in this case the decays of the lightest Higgs boson into l^{+} l^{-} + X may play an essential role in the Higgs searches.

hep-ph↗
arXiv2010

Dark Energy density in Split SUSY models inspired by degenerate vacua

It is well known that global symmetries protect local supersymmetry and a zero value for the cosmological constant in no--scale supergravity. The breakdown of these symmetries, which ensure the vanishing of the vacuum energy density, results in a set of degenerate vacua with broken and unbroken supersymmetry leading to the natural realisation of the multiple point principle (MPP). Assuming the degeneracy of vacua with broken and unbroken SUSY in the hidden sector we estimate the value of the cosmological constant. We argue that the observed value of the dark energy density can be reproduced in the split-SUSY scenario if the SUSY breaking scale is of the order of 10^{10} GeV.

hep-ph↗
arXiv2009

Predictions of the Constrained Exceptional Supersymmetric Standard Model

We discuss the predictions of a constrained version of the exceptional supersymmetric standard model (cE6SSM), based on a universal high energy soft scalar mass m_0, soft trilinear coupling A_0 and soft gaugino mass M_1/2. We predict a supersymmetry (SUSY) spectrum containing a light gluino, a light wino-like neutralino and chargino pair and a light bino-like neutralino, with other sparticle masses except the lighter stop being much heavier. In addition, the cE6SSM allows the possibility of light exotic colour triplet charge 1/3 fermions and scalars, leading to early exotic physics signals at the LHC. We focus on the possibility of a Z' gauge boson with mass close to 1 TeV, and low values of (m0,M_1/2), which would correspond to an LHC discovery using "first data", and propose a set of benchmark points to illustrate this.

hep-ph↗
arXiv2009

On the origin of approximate custodial symmetry in the Two-Higgs Doublet Model

We argue that the consistent implementation of the multiple point principle (MPP) in the general non-supersymmetric two Higgs doublet model (2HDM) can lead to a set of approximate global custodial symmetries that ensure CP conservation in the Higgs sector and the absence of flavour changing neutral currents (FCNC) in the considered model. In particular the existence of a large set of degenerate vacua at some high energy scale $Λ$ caused by the MPP can result in approximate U(1) and Z(2) symmetries that suppress FCNC and CP--violating interactions in the 2HDM. We explore the renormalisation group (RG) flow of the Yukawa and Higgs couplings within the MPP inspired 2HDM with approximate custodial symmetries and show that the solutions of the RG equations are focused near quasi--fixed points at low energies if the MPP scale scale $Λ$ is relatively high. We study the Higgs spectrum and couplings near the quasi--fixed point at moderate values of $\tanβ$ and compute a theoretical upper bound on the lightest Higgs boson mass. If $Λ\gtrsim 10^{10} {GeV}$ the lightest CP--even Higgs boson is always lighter than $125 {GeV}$. When the MPP scale is low, the mass of the lightest Higgs particle can reach $180-220 {GeV}$ while its coupling to the top quark can be significantly larger than in the SM, resulting in the enhanced production of Higgs bosons at the LHC.

hep-ph↗
arXiv2009

The constrained E6SSM

We discuss the predictions of a constrained version of the exceptional supersymmetric standard model (cE6SSM), with a universal high energy soft scalar mass, soft trilinear coupling and soft gaugino mass. The spectrum includes a light gluino, a light wino-like neutralino and chargino pair and a light bino-like neutralino, with other sparticle masses except the lighter stop being much heavier. We also discuss scenarios with an extra light exotic colour triplet of fermions and scalars and a TeV scale Z', which lead to early exotic physics signals at the LHC.

hep-ph↗
arXiv2009

Phenomenological Consequences of the Constrained Exceptional Supersymmetric Standard Model

The Exceptional Supersymmetric Standard Model (E$_6$SSM) provides a low energy alternative to the MSSM, with an extra gauged U(1)$_N$ symmetry, solving the $μ$-problem of the MSSM. Inspired by the possible embedding into an E$_6$ GUT, the matter content fills three generations of E$_6$ multiplets, thus predicting exciting exotic matter such as diquarks or leptoquarks. We present predictions from a constrained version of the model (cE$_6$SSM), with a universal scalar mass $m_0$, trilinear mass $A$ and gaugino mass $M_{1/2}$. We reveal a large volume of the cE$_6$SSM parameter space where the correct breakdown of the gauge symmetry is achieved and all experimental constraints satisfied. We predict a hierarchical particle spectrum with heavy scalars and light gauginos, while the new exotic matter can be light or heavy depending on parameters. We present representative cE$_6$SSM scenarios, demonstrating that there could be light exotic particles, like leptoquarks and a U(1)$_N$ Z' boson, with spectacular signals at the LHC.

hep-ph↗
arXiv2009

On the Smallness of the Cosmological Constant in SUGRA Models Inspired by Degenerate Vacua

In the no-scale supergravity global symmetries protect local supersymmetry and a zero value for the cosmological constant. The breakdown of these symmetries, which ensures the vanishing of the vacuum energy density, results in a set of degenerate vacua with broken and unbroken supersymmetry leading to the natural realisation of the multiple point principle (MPP). In the MPP inspired SUGRA models the cosmological constant is naturally tiny.

hep-ph↗
arXiv2009

Unification of Gauge Couplings in the E(6)SSM

We argue that in the two-loop approximation gauge coupling unification in the exceptional supersymmetric standard model can be achieved for any phenomenologically reasonable value of strong gauge coupling at the electroweak scale consistent with the experimentally measured central value.

hep-ph↗
arXiv2009

The Constrained Exceptional Supersymmetric Standard Model

We propose and study a constrained version of the Exceptional Supersymmetric Standard Model (E6SSM), which we call the cE6SSM, based on a universal high energy scalar mass m_0, trilinear scalar coupling A_0 and gaugino mass M_{1/2}. We derive the Renormalisation Group (RG) Equations for the cE6SSM, including the extra U(1)_{N} gauge factor and the low energy matter content involving three 27 representations of E6. We perform a numerical RG analysis for the cE6SSM, imposing the usual low energy experimental constraints and successful Electro-Weak Symmetry Breaking (EWSB). Our analysis reveals that the sparticle spectrum of the cE6SSM involves a light gluino, two light neutralinos and a light chargino. Furthermore, although the squarks, sleptons and Z' boson are typically heavy, the exotic quarks and squarks can also be relatively light. We finally specify a set of benchmark points which correspond to particle spectra, production modes and decay patterns peculiar to the cE6SSM, altogether leading to spectacular new physics signals at the Large Hadron Collider (LHC).

hep-ph↗
arXiv2008

Lightest Neutralino Mass in the MNSSM

We argue that the allowed range of the mass of the lightest neutralino in the MNSSM is limited. We establish the theoretical upper bound on the lightest neutralino mass and obtain an approximate solution for this mass.

hep-ph↗
arXiv2008

Cosmological Constant in SUGRA Models Inspired by Degenerate Vacua

It is well known that global symmetries protect local supersymmetry and a zero value for the cosmological constant in no--scale supergravity. A particular breakdown of these symmetries, which ensures the vanishing of the vacuum energy density, leads to the natural realisation of the multiple point principle (MPP). In the MPP inspired SUGRA models the cosmological constant is naturally tiny.

hep-th↗
arXiv2008

The Constrained E$_6$SSM

We present a self--consistent $E_6$ inspired supersymmetric model with an extra $U(1)_{N}$ gauge symmetry under which right-handed neutrinos have zero charge. We explore the particle spectrum within the constrained version of this exceptional supersymmetric standard model (E$_6$SSM) and discuss its possible collider signatures.

hep-ph↗
arXiv2008

Leptogenesis in the Exceptional Supersymmetric Standard Model: flavour dependent lepton asymmetries

We calculate flavour dependent lepton asymmetries within the $E_6$ inspired Supersymmetric Standard Model ($\rm E_6SSM$), which has an extra $U(1)_N$ symmetry. In this model, the right-handed neutrino doesn't participate in gauge interactions, allowing it to be used for both the see--saw mechanism and leptogenesis. Extra Higgs, leptons and leptoquarks predicted by the E$_6$SSM contribute to the ordinary lepton CP asymmetries induced by the decays of the lightest right--handed neutrino (and sneutrino) and give rise to a set of extra decay asymmetries. We find that the CP asymmetries can be relatively large, even when the lightest right--handed neutrino is as light as $10^6 {GeV}$.

hep-ph↗
arXiv2008

Leptogenesis in the E$_6$SSM: Flavour Dependent Lepton Asymmetries

We discuss flavour dependent lepton asymmetries in the Exceptional Supersymmetric Standard Model (E$_6$SSM). In the E$_6$SSM, the right-handed neutrinos do not participate in gauge interactions, and they decay into leptons and leptoquarks. Their Majorana nature allows violation of lepton number. New particles and interactions can result in substantial lepton asymmetries, even for scales as low as $10^6 {\rm GeV}$.

hep-ph↗
arXiv2008

Fixed point scenario in the Two Higgs Doublet Model inspired by degenerate vacua

We consider the renormalisation group flow of Higgs and Yukawa couplings within the simplest non--supersymmetric two Higgs doublet extension of the Standard Model (SM). In this model the couplings are adjusted so that the multiple point principle (MPP) assumption, which implies the existence of a large set of degenerate vacua at some high energy scale $Λ$, is realised. When the top quark Yukawa coupling at the scale $Λ$ is large, the solutions of RG equations in this MPP inspired 2 Higgs Doublet Model (2HDM) converge to quasi--fixed points. We analyse the Higgs spectrum and couplings in the quasi--fixed point scenario and compute a theoretical upper bound on the lightest Higgs boson mass. When the scale $Λ$ is low, the coupling of the SM--like Higgs scalar to the top quark can be significantly larger in the considered model than in the SM, resulting in the enhanced production of Higgs bosons at the LHC.

hep-ph↗