Search

According to recent measurements, dark matter magnetic dipole moment is strongly constrained. In the composite Higgs models the magnetic dipole moment of the Dirac dark matter fermion and its mass can be suppressed by the approximate U(1) symmetry. We consider E_6 inspired composite Higgs model (E_6CHM) with U(1) symmetry violating operators, which give rise to dark matter's mass and coupling constant to Higgs boson. The dependence of the spin-independent dark matter-nucleon scattering cross section on the E_6CHM parameters is explored. We argue that there are regions of the parameter space which are still safe from all current constraints and may lead to spectacular LHC signatures., Comment: 27 pages, 3 figure, major changes to the text, added references, version accepted for publication in Physical Review D

Local supersymmetry (SUSY) provides an attractive framework for the incorporation of gravity and unification of gauge interactions within Grand Unified Theories (GUTs). Its breakdown can lead to a variety of models with softly broken SUSY at low energies. In this review article we focus on the SUSY extension of the Standard Model (SM) with an extra U(1)_{N} gauge symmetry originating from a string-inspired E_6 grand unified gauge group. Only in this U(1) extension of the minimal supersymmetric standard model (MSSM) inspired by E_6 GUTs the right-handed neutrinos can be superheavy providing a mechanism for the generation of the lepton and baryon asymmetry of the Universe. The particle content of this exceptional supersymmetric standard model (E_6SSM) includes three 27 representations of the E_6 group, to ensure anomaly cancellation, plus a pair of SU(2)_W doublets as required for gauge coupling unification. Thus E_6SSM involves extra exotic matter beyond the MSSM. We consider symmetries that permit to suppress non-diagonal flavour transitions and rapid proton decay, as well as gauge coupling unification, the breakdown of the gauge symmetry and the spectrum of Higgs bosons in this model. The possible Large Hadron Collider (LHC) signatures caused by the presence of exotic states are also discussed., Comment: 39 pages, 3 figure. arXiv admin note: text overlap with arXiv:1205.5967, arXiv:hep-ph/0510419

The breakdown of SU(6) global symmetry down to its SU(5) subgroup near the scale f > 10 TeV in the strongly interacting sector within the E_6 inspired composite Higgs model (E6CHM) gives rise to a set of pseudo-Nambu-Goldstone bosons (pNGBs) that involves one Standard Model (SM) singlet scalar, a SM-like Higgs doublet and an SU(3)_C triplet of scalar fields, $T$. We argue that the baryon number violation in the E6CHM can induce the observed matter-antimatter asymmetry if CP is violated. The coloured triplet of scalar fields with mass in the few TeV range plays a key role in this process and may lead to a distinct new physics signal that can be detected at the LHC in the near future., Comment: Presented at International Bogolyubov Conference "Problems of Theoretical and Mathematical Physics", Moscow-Dubna, Russia, 9 - 13 September, 2019. arXiv admin note: substantial text overlap with arXiv:1808.01982

In N=1 supergravity the scalar potential may have supersymmetric (SUSY) and non-supersymmetric Minkowski vacua (associated with supersymmetric and physical phases) with vanishing energy density. In the supersymmetric Minkowski (second) phase some breakdown of SUSY may be induced by non-perturbative effects in the observable sector that give rise to a tiny positive vacuum energy density. Postulating the exact degeneracy of the physical and second vacua as well as assuming that at high energies the couplings in both phases are almost identical, one can estimate the dark energy density in these vacua. It is mostly determined by the SUSY breaking scale M_S in the physical phase. Exploring the two-loop renormalization group (RG) flow of couplings in these vacua we find that the measured value of the cosmological constant can be reproduced if M_S varies from 20 TeV to 400 TeV. We also argue that this prediction for the SUSY breaking scale is consistent with the upper bound on M_S in the higgsino dark matter scenario., Comment: 15 pages, 1 figure, references added

The strongly interacting sector in the E6 inspired composite Higgs model (E6CHM) with baryon number violation possesses SU(6)\times U(1)_L global symmetry. In the weakly-coupled sector of this model the U(1)_L symmetry associated with lepton number conservation is broken down to a Z^L_2 discrete symmetry, which stabilizes the proton. Near the scale f > 10 TeV the SU(6) symmetry is broken down to its SU(5) subgroup, giving rise to a set of pseudo-Nambu-Goldstone bosons (pNGBs) that involves the SM-like Higgs doublet, a scalar coloured triplet and a SM singlet boson. Because f is so high, all baryon number violating operators are sufficiently strongly suppressed. Nevertheless, in this variant of the E6CHM the observed matter-antimatter asymmetry can be induced if CP is violated. The pNGB scalar coloured triplet plays a key role in this process and leads to a distinct signature that may be detected at the LHC in the near future., Comment: Presented at 20th International Seminar on High Energy Physics (QUARKS-2018), Valday, Russia, 27 May - 2 June, 2018

The breakdown of E_6 within the supersymmetric (SUSY) Grand Unified Theories (GUTs) can result in SUSY extensions of the standard model (SM) based on the SM gauge group together with extra U(1) gauge symmetry under which right-handed neutrinos have zero charge. In these U(1)_N extensions of the minimal supersymmetric standard model (MSSM) a single discrete \tilde{Z}^H_2 symmetry may be used to suppress the most dangerous operators, that give rise to proton decay as well as non-diagonal flavour transitions at low energies. The SUSY models under consideration involves Z' and extra exotic matter beyond the MSSM. We discuss leptogenesis within this SUSY model and argue that the extra exotic states may lead to the non--standard Higgs decays., Comment: Presented at Conference on Particles and Cosmology, Singapore, 5-9 March 2018

We explore leptogenesis within the E6 inspired U(1) extension of the MSSM in which exact custodial symmetry forbids tree-level flavour-changing transitions and the most dangerous baryon and lepton number violating operators. This supersymmetric (SUSY) model involves extra exotic matter beyond the MSSM. In the simplest phenomenologically viable scenarios the lightest exotic fermions are neutral and stable. These states should be substantially lighter than 1 eV forming hot dark matter in the Universe. The low-energy effective Lagrangian of the SUSY model under consideration possesses an approximate global U(1)_E symmetry associated with the exotic states. The U(1)_E symmetry is explicitly broken because of the interactions between the right-handed neutrino superfields and exotic matter supermultiplets. As a consequence the decays of the lightest right-handed neutrino/sneutrino give rise to both U(1)_E and U(1)_{B-L} asymmetries. When all right-handed neutrino/sneutrino are relatively light \sim 10^6-10^7 GeV the appropriate amount of the baryon asymmetry can be induced via these decays if the Yukawa couplings of the lightest right-handed neutrino superfields to the exotic matter supermultiplets vary between 10^{-4}-10^{-3}., Comment: 17 pages, 1 figure

In the E6 inspired composite Higgs model (E6CHM) the strongly interacting sector possesses an SU(6) global symmetry which is expected to be broken down to its SU(5) subgroup at the scale f > 10 TeV. This breakdown results in a set of pseudo-Nambu-Goldstone bosons (pNGBs) that includes one Standard Model (SM) singlet scalar, a SM-like Higgs doublet and an SU(3)_C triplet of scalar fields, T. In the E6CHM the Z^L_{2} symmetry, which is a discrete subgroup of the U(1)_L associated with lepton number conservation, can be used to forbid operators which lead to rapid proton decay. The remaining baryon number violating operators are sufficiently strongly suppressed because of the large value of the scale f. We argue that in this variant of the E6CHM a sizeable baryon number asymmetry can be induced if CP is violated. At the same time, the presence of the SU(3)_C scalar triplet with mass in the few TeV range may give rise to spectacular new physics signals that may be detected at the LHC in the near future., Comment: 4 pages, 1 figure

In N=1 supergravity the tree-level scalar potential of the hidden sector may have a minimum with broken local supersymmetry (SUSY) as well as a supersymmetric Minkowski vacuum. These vacua can be degenerate, allowing for a consistent implementation of the multiple point principle. The first minimum where SUSY is broken can be identified with the physical phase in which we live. In the second supersymmetric phase, in flat Minkowski space, SUSY may be broken dynamically either in the observable or in the hidden sectors inducing a tiny vacuum energy density. We argue that the exact degeneracy of these phases may shed light on the smallness of the cosmological constant. Other possible phenomenological implications are also discussed. In particular, we point out that the presence of such degenerate vacua may lead to small values of the quartic Higgs coupling and its beta function at the Planck scale in the physical phase., Comment: Presented at the International Conference on Cosmology, Gravitational Waves and Particles, Singapore, 6-10 February, 2017

This Report summarizes the results of the activities of the LHC Higgs Cross Section Working Group in the period 2014-2016. The main goal of the working group was to present the state-of-the-art of Higgs physics at the LHC, integrating all new results that have appeared in the last few years. The first part compiles the most up-to-date predictions of Higgs boson production cross sections and decay branching ratios, parton distribution functions, and off-shell Higgs boson production and interference effects. The second part discusses the recent progress in Higgs effective field theory predictions, followed by the third part on pseudo-observables, simplified template cross section and fiducial cross section measurements, which give the baseline framework for Higgs boson property measurements. The fourth part deals with the beyond the Standard Model predictions of various benchmark scenarios of Minimal Supersymmetric Standard Model, extended scalar sector, Next-to-Minimal Supersymmetric Standard Model and exotic Higgs boson decays. This report follows three previous working-group reports: Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002), Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (CERN-2012-002), and Handbook of LHC Higgs Cross Sections: 3. Higgs properties (CERN-2013-004). The current report serves as the baseline reference for Higgs physics in LHC Run 2 and beyond., Comment: 869 pages, 295 figures, 248 tables and 1645 citations. Working Group web page: https://twiki.cern.ch/twiki/bin/view/LHCPhysics/LHCHXSWG

We investigate dark matter in a constrained $E_6$ inspired supersymmetric model with an exact custodial symmetry and compare with the CMSSM. The breakdown of $E_6$ leads to an additional $U(1)_N$ symmetry and a discrete matter parity. The custodial and matter symmetries imply there are two stable dark matter candidates, though one may be extremely light and contribute negligibly to the relic density. We demonstrate that a predominantly Higgsino, or mixed bino-Higgsino, neutralino can account for all of the relic abundance of dark matter, while fitting a 125 GeV SM-like Higgs and evading LHC limits on new states. However we show that the recent LUX 2016 limit on direct detection places severe constraints on the mixed bino-Higgsino scenarios that explain all of the dark matter. Nonetheless we still reveal interesting scenarios where the gluino, neutralino and chargino are light and discoverable at the LHC, but the full relic abundance is not accounted for. At the same time we also show that there is a huge volume of parameter space, with a predominantly Higgsino dark matter candidate that explains all the relic abundance, that will be discoverable with XENON1T. Finally we demonstrate that for the $E_6$ inspired model the exotic leptoquarks could still be light and within range of future LHC searches., Comment: 51 pages + 1 appendix, 10 figures, 2 tables; typos corrected and references added; matches version accepted for publication in JHEP

In the E6 inspired composite Higgs model (E6CHM) the strongly interacting sector possesses an SU(6)\times U(1)_B\times U(1)_L global symmetry. Near scale f\gtrsim 10 TeV the SU(6) symmetry is broken down to its SU(5) subgroup, that involves the standard model (SM) gauge group. This breakdown of SU(6) leads to a set of pseudo--Nambu--Goldstone bosons (pNGBs) including a SM--like Higgs and a SM singlet pseudoscalar A. Because of the interactions between A and exotic fermions, which ensure the approximate unification of the SM gauge couplings and anomaly cancellation in this model, the couplings of the pseudoscalar A to gauge bosons get induced. As a result, the SM singlet pNGB state A with mass around 750 GeV may give rise to sufficiently large cross section of pp\to \gamma\gamma that can be identified with the recently observed diphoton excess., Comment: Presented at 19th International Seminar on High Energy Physics (QUARKS-2016), Pushkin, Russia, 29 May - 4 June, 2016

The breakdown of the SU(6) global symmetry to its SU(5) subgroup, that contains the standard model (SM) gauge group, in the E6 inspired composite Higgs model (E6CHM) results in a set of pseudo-Nambu-Goldstone bosons (pNGBs). This set, in particular, involves the SM-like Higgs doublet and a SM singlet boson. In the limit when CP is conserved the SM singlet scalar A is a CP-odd state that does not mix with the SM-like Higgs. The interactions of A with exotic matter beyond the SM, which ensures anomaly cancellation and approximate gauge coupling unification, can induce couplings of this pseudoscalar to the SM gauge bosons. We specify the interactions of the SM singlet pNGB state with the exotic vector-like fermions, top quark and SM gauge bosons. Also we explore the dependence of the branching ratios of the pseudoscalar A and its LHC production cross section on the parameters of the E6CHM., Comment: 29 pages, 4 figures, version accepted for publication in Journal of Physics G

We study the decays of the lightest CP-even Higgs boson into a pair of pseudoscalar Higgs states within U(1)_N extensions of the MSSM., Comment: Presented at 17th Lomonosov Conference on Elementary Particle Physics, Moscow, Russia, 20-26 August, 2015

The 750-760 GeV diphoton resonance may be identified as one or two scalars and/or one or two pseudoscalars contained in the two singlet superfields S_{1,2} arising from the three 27-dimensional representations of E_6 . The three 27s also contain three copies of colour-triplet charge \mp 1/3 vector-like fermions D,\bar{D} and two copies of charged inert Higgsinos \tilde{H}^{+},\tilde{H}^{-} to which the singlets S_{1,2} may couple. We propose a variant of the E_6SSM where the third singlet S_3 breaks a gauged U(1)_N above the TeV scale, predicting Z'_N, D,\bar{D}, \tilde{H}^{+},\tilde{H}^{-} at LHC Run 2, leaving the two lighter singlets S_{1,2} with masses around 750 GeV. We calculate the branching ratios and cross-sections for the two scalar and two pseudoscalar states associated with the S_{1,2} singlets, including possible degeneracies and maximal mixing, subject to the constraint that their couplings remain perturbative up to the unification scale., Comment: 22 pages, 4 figures, some minor changes to the text, references added

We explore the relic density of dark matter and the particle spectrum within a constrained version of an $E_6$ inspired SUSY model with an extra $U(1)_N$ gauge symmetry. In this model a single exact custodial symmetry forbids tree-level flavor-changing transitions and the most dangerous baryon and lepton number violating operators. We present a set of benchmark points showing scenarios that have a SM-like Higgs mass of 125 GeV and sparticle masses above the LHC limits. They lead to striking new physics signatures which may be observed during run II of the LHC and can distinguish this model from the simplest SUSY extensions of the SM. At the same time these benchmark scenarios are consistent with the measured dark matter abundance and necessarily lead to large dark matter direct detection cross sections close to current limits and observable soon at the XENON1T experiment., Comment: 9 pages, no figures, 3 tables; references updated and minor corrections, branching ratios added to Table 3, matches version published in Phys. Lett. B

The phenomenological implications of the E6 inspired supersymmetric models based on the Standard Model gauge group together with extra U(1)_N gauge symmetry under which right-handed neutrinos have zero charge are examined. In these models single discrete symmetry forbids the tree-level flavour changing processes and the most dangerous operators that violate baryon and lepton numbers. The two-loop renormalisation group flow of the gauge and Yukawa couplings is explored and the qualitative pattern of the Higgs spectrum in the case of the quasi-fixed point scenario is discussed. These E6 inspired models contain two dark-matter candidates. The presence of exotic states in these models gives rise to the nonstandard decays of the lightest Higgs boson which are also considered., Comment: Poster presented at EPS-HEP 2015, Vienna, Austria, July 2015, 6 pages, 1 figure

We argue that the exact degeneracy of vacua in N=1 supergravity can shed light on the smallness of the cosmological constant. The presence of such vacua, which are degenerate to very high accuracy, may also result in small values of the quartic Higgs coupling and its beta function at the Planck scale in the phase in which we live., Comment: Parallel talk at EPS-HEP 2015, Vienna, Austria, July 2015, 6 pages. arXiv admin note: text overlap with arXiv:1410.6620

The Next-to-Minimal Supersymmetric extension of the Standard Model (NMSSM) features extra new sources for CP violation. In contrast to the MSSM CP violation can already occur at tree level in the Higgs sector. We investigate the range of possible allowed CP-violating phases by taking into account the constraints arising from the measurements of the Electric Dipole Moments (EDMs) and the latest LHC Higgs data. Our analysis shows that large CP-violating phases, that are NMSSM-specific, are not in conflict with the EDMs. They are dominantly constrained by the Higgs data in this case. We use our results to investigate the prospects of measuring CP violation through the combined measurement of Higgs rates, on the one hand, and in observables based on CP-violating Higgs couplings to tau leptons on the other hand., Comment: 32 pages

We consider a composite Higgs model embedded into a Grand Unified Theory(GUT) based on the E_6 gauge group. The phenomenological viability of this E_6 inspired composite Higgs model (E6CHM) implies that standard model (SM) elementary fermions with different baryon or lepton number should stem from different 27 representations of E_6. We present a six-dimensional orbifold GUT model in which the E_6 gauge symmetry is broken to the SM gauge group so that the appropriate splitting of the bulk 27-plets takes place. In this model the strongly coupled sector is localised on one of the branes and possesses an SU(6) global symmetry that contains the SU(3)_C\times SU(2)_W\times U(1)_Y subgroup. In this case the approximate gauge coupling unification can be attained if the right-handed top quark is a composite state and the elementary sector involves extra exotic matter beyond the SM which ensures anomaly cancellation. The breakdown of the approximate SU(6) symmetry at low energies in this model results in a set of the pseudo-Nambu-Goldstone states which include a Higgs doublet and scalar colour triplet. We discuss the generation of the masses of the SM fermions in the E6CHM. The presence of the TeV scale vector-like exotic quarks and scalar colour triplet may provide spectacular new physics signals that can be observed at the LHC., Comment: 38 pages, minor changes to the text, references added

We consider the exotic decays of the SM-like Higgs state within the E6 inspired supersymmetric (SUSY) models. In these models the lightest SUSY particle (LSP) can be substantially lighter than 1 eV forming hot dark matter in the Universe. The next--to--lightest SUSY particle (NLSP) also tend to be light. We argue that the NLSP with GeV scale mass may lead to the substantial branching ratio of the nonstandard decays of the SM-like Higgs boson into NLSPs., Comment: Parallel talk at ICHEP 2014, Valencia, Spain, July 2014, 6 pages, based on arXiv:1308.1021

In N=1 supergravity the scalar potential of the hidden sector may have degenerate supersymmetric (SUSY) and non-supersymmetric Minkowski vacua. In this case local SUSY in the second supersymmetric Minkowski phase can be broken dynamically. Assuming that such a second phase and the phase associated with the physical vacuum are exactly degenerate, we estimate the value of the cosmological constant. We argue that the observed value of the dark energy density can be reproduced if in the second vacuum local SUSY breaking is induced by gaugino condensation at a scale which is just slightly lower than \Lambda_{QCD} in the physical vacuum. The presence of a third degenerate vacuum, in which local SUSY and electroweak (EW) symmetry are broken near the Planck scale, may lead to small values of the quartic Higgs self--coupling and the corresponding beta function at the Planck scale in the phase in which we live., Comment: Parallel talk at ICHEP 2014, Valencia, Spain, July 2014, 6 pages, 1 figure

In U(1) extensions of the Minimal Supersymmetric extension of the Standard Model there is a simple mechanism that leads to a heavy Z' boson with a mass which is substantially larger than the supersymmetry breaking scale. This mechanism may also result in a pseudoscalar state that is light enough for decays of the 125 GeV Standard Model-like Higgs boson into a pair of such pseudoscalars to be kinematically allowed. We study these decays within E6 inspired supersymmetric models with an exact custodial symmetry that forbids tree-level flavor-changing transitions and the most dangerous baryon and lepton number violating operators. We argue that the branching ratio of the lightest Higgs boson decays into a pair of the light pseudoscalar states may not be negligibly small., Comment: 38 pages, 1 figure, some minor changes to the text, references added

We investigate the discovery prospects for NMSSM Higgs bosons during the 13~TeV run of the LHC. While one of the neutral Higgs bosons is demanded to have a mass around 125~GeV and Standard Model (SM)-like properties, there can be substantially lighter, nearby or heavier Higgs bosons, that have not been excluded yet by LEP, Tevatron or the 8~TeV run of the LHC. The challenge consists in discovering the whole NMSSM Higgs mass spectrum. We present the rates for production and subsequent decay of the neutral NMSSM Higgs bosons in the most promising final states and discuss their possible discovery. The prospects for pinning down the Higgs sector of the Natural NMSSM will be analysed taking into account alternative search channels. We give a series of benchmark scenarios compatible with the experimental constraints, that feature Higgs-to-Higgs decays and entail (exotic) signatures with multi-fermion and/or multi-photon final states. These decay chains furthermore give access to the trilinear Higgs self-couplings. We briefly discuss the possibility of exploiting coupling sum rules in case not all the NMSSM Higgs bosons are discovered.

The empirical mass of the Higgs boson suggests small to vanishing values of the quartic Higgs self--coupling and the corresponding beta function at the Planck scale, leading to degenerate vacua. This leads us to suggest that the measured value of the cosmological constant can originate from supergravity (SUGRA) models with degenerate vacua. This scenario is realised if there are at least three exactly degenerate vacua. In the first vacuum, associated with the physical one, local supersymmetry (SUSY) is broken near the Planck scale while the breakdown of the SU(2)_W\times U(1)_Y symmetry takes place at the electroweak (EW) scale. In the second vacuum local SUSY breaking is induced by gaugino condensation at a scale which is just slightly lower than \Lambda_{QCD} in the physical vacuum. Finally, in the third vacuum local SUSY and EW symmetry are broken near the Planck scale., Comment: 12 pages, 1 figure, version of the paper published in PLB

We analyse the two-loop renormalization group (RG) flow of the gauge and Yukawa couplings within the E6 inspired supersymmetric (SUSY) models with extra U(1)_{N} gauge symmetry under which right-handed neutrinos have zero charge. In these models single discrete \tilde{Z}^{H}_2 symmetry forbids the tree-level flavor-changing transitions and the most dangerous baryon and lepton number violating operators. We consider two different scenarios A and B that involve extra matter beyond the MSSM contained in three and four 5+\overline{5} representations of SU(5) respectively plus three SU(5) singlets which carry U(1)_{N} charges. In the scenario A the measured values of the SU(2)_W and U(1)_Y gauge couplings lie near the fixed points of the RG equations. In the scenario B the contribution of two--loop corrections spoils the unification of gauge couplings resulting in the appearance of the Landau pole below the Grand Unification scale M_X. The solutions for the Yukawa couplings also approach the quasi fixed points with increasing their values at the scale M_X. We calculate the two--loop upper bounds on the lightest Higgs boson mass in the vicinity of these quasi fixed points and compare the results of our analysis with the corresponding ones in the NMSSM. In all these cases the theoretical restrictions on the SM--like Higgs boson mass are rather close to 125 GeV., Comment: 30 pages, 2 figures, some minor changes to the text, references added

We study the decays of the SM-like Higgs state within the E6 inspired supersymmetric (SUSY) models with exact custodial symmetry that forbids tree-level flavor-changing transitions and the most dangerous baryon and lepton number violating operators. In these models there are two states which are absolutely stable and can contribute to the dark matter density. One of them is the lightest SUSY particle (LSP) which is expected to be lighter than 1 eV forming hot dark matter in the Universe. The presence of another stable neutral state allows to account for the observed cold dark matter density. In the considered SUSY models next-to-lightest SUSY particle (NLSP) also tend to be light. We argue that the NLSP with GeV scale mass can result in the substantial branching ratio of the nonstadard decays of the lightest Higgs boson., Comment: 15 pages, minor changes to the text. arXiv admin note: text overlap with arXiv:1201.5488 by other authors

We study the parameter space of the constrained exceptional supersymmetric standard model (cE6SSM) consistent with a Higgs signal near 125 GeV and the LHC searches for squarks, gluinos and Z'. The cE6SSM parameter space consistent with correct electroweak symmetry breaking, is represented by scans in the (m0, M1/2) plane for fixed Z' mass and tan beta, with squark, gluino and Higgs masses plotted as contours in this plane. We find that a 125 GeV Higgs mass only arises for a sufficiently large Z' mass, mostly above current limits, and for particular regions of squark and gluino masses corresponding to multi-TeV squark masses, but with lighter gluinos typically within reach of the LHC 8 TeV or forthcoming 14 TeV runs. Successful dark matter relic abundance may be achieved over all the parameter space, assuming a bino-like LSP with a nearby heavier inert Higgsino doublet and decoupled inert singlinos, resulting in conventional gluino decay signatures. A set of typical benchmark points with a Higgs near 125 GeV is provided which exemplifies these features., Comment: 31 pages, 7 figures, V2 added three references

The breakdown of E_6 gauge symmetry at high energies may lead to supersymmetric (SUSY) models based on the Standard Model (SM) gauge group together with extra U(1)_{\psi} and U(1)_{\chi} gauge symmetries. To ensure anomaly cancellation the particle content of these E_6 inspired models involves extra exotic states that generically give rise to non-diagonal flavour transitions and rapid proton decay. We argue that a single discrete \tilde{Z}^{H}_2 symmetry can be used to forbid tree-level flavor-changing transitions, as well as the most dangerous baryon and lepton number violating operators. We present 5D and 6D orbifold GUT constructions that lead to the E_6 inspired SUSY models of this type. The breakdown of U(1)_{\psi} and U(1)_{\chi} gauge symmetries that preserves E_6 matter parity assignment guarantees that ordinary quarks and leptons and their superpartners, as well as the exotic states which originate from 27 representations of E_6 survive to low energies. These E_6 inspired models contain two dark-matter candidates and must also include additional TeV scale vectorlike lepton or vectorlike down type quark states to render the lightest exotic quark unstable. We examine gauge coupling unification in these models and discuss their implications for collider phenomenology and cosmology., Comment: 68 pages, 2 figures, changes to the text caused mainly by the recently reported evidence for a Higgs boson

The recent LHC indications of a SM-like Higgs boson near 125 GeV are consistent not only with the Standard Model (SM) but also with Supersymmetry (SUSY). However naturalness arguments disfavour the Minimal Supersymmetric Standard Model (MSSM). We consider the Next-to-Minimal Supersymmetric Standard Model (NMSSM) with a SM-like Higgs boson near 125 GeV involving relatively light stops and gluinos below 1 TeV in order to satisfy naturalness requirements. We are careful to ensure that the chosen values of couplings do not become non perturbative below the grand unification (GUT) scale, although we also examine how these limits may be extended by the addition of extra matter to the NMSSM at the two-loop level. We then propose four sets of benchmark points corresponding to the SM-like Higgs boson being the lightest or the second lightest Higgs state in the NMSSM or the NMSSM-with-extra-matter. With the aid of these benchmark points we discuss how the NMSSM Higgs boson near 125 GeV may be distinguished from the SM Higgs boson in future LHC searches., Comment: 40 pages, 1 figure; Minor changes and further references included

These lectures are a very brief introduction to low energy supersymmetry (SUSY). The approach to the construction of SUSY Lagrangians based on the superfield formalism is considered. The minimal supersymmetric standard model (MSSM) is specified. The breakdown of gauge symmetry and Higgs phenomenology within the simplest SUSY extensions of the standard model (SM) are briefly reviewed. The upper bound on the mass of the lightest Higgs boson and little hierarchy problem in SUSY models are discussed., Comment: Course lectures presented at the Dynasty Foundation Summer School, Protvino, Moscow region, Russia, 10-20 August, 2009; published in the Proceedings of the Dynasty Foundation Summer School, p.108-154 (2011)

We consider collider signatures of the exceptional supersymmetric (SUSY) standard model (E6SSM). This E6 inspired SUSY model is based on the SM gauge group together with an extra U(1) gauge symmetry under which right--handed neutrinos have zero charge. To ensure anomaly cancellation and gauge coupling unification the low energy matter content of the E6SSM involve extra exotic matter beyond the MSSM. We discuss the collider signatures associated with the production of new particles predicted by the E6SSM and consider the implications of this model for dark matter and Higgs phenomenology. Since exotic quarks in the E6SSM can be either diquarks or leptoquarks they may provide spectacular new physics signals at the LHC., Comment: Parallel talk presented at 2011 Meeting of the Division of Particles and Fields of the American Physical Society (DPF 2011), Providence, Rhode Island, USA, 9-13 August 2011, 8 pages

We study the decays of the lightest Higgs boson within the exceptional supersymmetric (SUSY) standard model (E6SSM). The E6SSM predicts three families of Higgs-like doublets plus three SM singlets that carry U(1)_{N} charges. One family of Higgs-like doublets and one SM singlet develop vacuum expectation values. The fermionic partners of other Higgs-like fields and SM singlets form inert neutralino and chargino states. Two lightest inert neutralinos tend to be the lightest and next-to-lightest SUSY particles (LSP and NLSP). The considered model can account for the dark matter relic abundance if the lightest inert neutralino has mass close to half the Z mass. In this case the usual SM-like Higgs boson decays more than 95% of the time into either LSPs or NLSPs. As a result the decays of the lightest Higgs boson into l^{+} l^{-} + X might play an essential role in the Higgs searches. This scenario also predicts other light inert chargino and neutralino states below 200 GeV and large LSP direct detection cross-sections which is on the edge of observability of XENON100., Comment: Parallel talk presented at 2011 Meeting of the Division of Particles and Fields of the American Physical Society (DPF 2011), Providence, Rhode Island, USA, 9-13 August 2011, 8 pages

In N=1 supergravity supersymmetric (SUSY) and non-supersymmetric Minkowski vacua originating in the hidden sector can be degenerate. In the supersymmetric phase in flat Minkowski space non-perturbative supersymmetry breakdown may take place in the observable sector, inducing a non-zero and positive vacuum energy density. Assuming that such a supersymmetric phase and the phase in which we live are degenerate, 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 of the supersymmetry breaking if the SUSY breaking scale is of order of 10^{10} GeV., Comment: 20 pages, 1 figure, some minor changes to the text, references added

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., Comment: Plenary talk at the XIXth International Workshop on High Energy Physics and Quantum Field Theory, Golitsyno, Moscow, Russia, September 2010, 15 pages

We discuss two striking Large Hadron Collider (LHC) signatures of the 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}. The first signature we discuss is that of light exotic colour triplet charge 1/3 fermions, which we refer to as D-fermions. We calculate the LHC production cross section of D-fermions, and discuss their decay patterns. Secondly we discuss the E6 type U(1)_N spin-1 Z' gauge boson and show how it may decay into exotic states, increasing its width and modifying the line shape of the dilepton final state. We illustrate these features using two representative cE6SSM benchmark points, including an "early LHC discovery" point, giving the Feynman rules and numerical values for the relevant couplings in order to facilitate further studies., Comment: 30 pages, 5 figures, corrections to figure captions

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., Comment: Parallel talk at the XIXth International Workshop on High Energy Physics and Quantum Field Theory, Golitsyno, Moscow, Russia, September 2010, 6 pages

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., Comment: Parallel talk at ICHEP 2010, Paris, France, July 2010, 4 pages

The Exceptional Supersymmetric (SUSY) Standard Model predicts three families of Higgs doublets plus three Higgs singlets, where one family develops vacuum expectation values (VEVs), while the remaining two which do not are called Inert. The model can account for the dark matter relic abundance if the two lightest Inert neutralinos, identified as the (next-to) lightest SUSY particles ((N)LSPs), have masses close to half the Z mass. In this case we find that the usual SM-like Higgs boson decays more than 95% of the time into either LSPs or NLSPs. The latter case produces a final state containing two leptons l^{+}l^{-} with an invariant mass less than or about 10 GeV. We illustrate this scenario with a set of benchmark points satisfying phenomenological constraints and the WMAP dark matter relic abundance. This scenario also predicts other light Inert chargino and neutralino states below 200 GeV, and large LSP direct detection cross-sections close to current limits and observable soon at XENON100., Comment: 39 pages, 2 figures, some minor changes to the text, references added, version to appear in Phys. Rev. D

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., Comment: To appear in proceedings of The 2009 Europhysics Conference on High Energy Physics, 16-22 July 2009 Krakow, Poland; 4 pages

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 $\mu$-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., Comment: Contribution to the proceedings of SUSY 09, Boston, USA, June 2009, 4 pages

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., Comment: Parallel talk at SUSY09, Boston, USA, June 2009, 5 pages

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., Comment: Parallel talk at SUSY09, Boston, USA, June 2009, 5 pages

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)., Comment: Version accepted for publication in Phys. Rev. D

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., Comment: 21 pages, 6 figures; version accepted for publication in Physics Letters B

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., Comment: Parallel talk at ICHEP08, Philadelphia, USA, July 2008, 4 pages

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., Comment: Parallel talk at ICHEP08, Philadelphia, USA, July 2008. 4 pages, 1 figure

We calculate flavour dependent lepton asymmetries within the $E_6$ inspired Supersymmetric Standard Model. Our analysis reveals that the substantial lepton CP asymmetries can be induced even if $M_1\simeq 10^6 {GeV}$., Comment: Poster presented at ICHEP08, Philadelphia, USA, July 2008. 3 pages, 2 figures

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., Comment: Poster presented at ICHEP08, Philadelphia, USA, July 2008. 3 pages, LaTeX, 2 eps figures