arXiv subjects

Ilia Gogoladze

Publications and source records attributed to Ilia Gogoladze.

At least 55 records · Page 3Linked to original sources

arXiv2011

Neutralino-Sbottom Coannihilation in SU(5)

We identify within the SU(5) framework the minimum number of soft supersymmetry breaking parameters which can yield a bottom squrak (sbottom) as the next to lightest supersymmetric particle. We focus in particular on the neutralino-sbottom coannihilation scenario which gives rise to the desired neutralino dark matter relic density. We find solutions in which the sbottom mass is greater than or of order 210 GeV, while the gluino and the first two family squarks are heavier than 1 TeV. Some benchmark points which can be tested at the LHC are presented.

hep-ph↗

arXiv2011

Sparticle Spectroscopy with Neutralino Dark matter from t-b-tau Quasi-Yukawa Unification

We consider two classes of t-b-tau quasi-Yukawa unification scenarios which can arise from realistic supersymmetric SO(10) and SU(4)_C X SU(2)_L X SU(2)_R models. We show that these scenarios can be successfully implemented in the CMSSM and NUHM1 frameworks, and yields a variety of sparticle spectra with WMAP compatible neutralino dark matter. In NUHM1 we find bino-higgsino dark matter as well as the stau coannihilation and A-funnel solutions. The CMSSM case yields the stau coannihilation and A-funnel solutions. The gluino and squark masses are found to lie in the TeV range.

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arXiv2011

SO(10) Yukawa Unification with mu < 0

We consider the low energy implications including particle spectroscopy of SO(10) inspired t-b-tau Yukawa coupling unification with mu < 0, where mu is the coefficient of the bilinear Higgs mixing term of the minimal supersymmetric standard model (MSSM). We imploy non-universal MSSM gaugino masses induced by SO(10) invariant dimension five operators, such that the total number of fundamental parameters is precisely the same as in Yukawa unified supersymmetric SO(10) models with universal gaugino masses and mu > 0. We find that t-b-tau Yukawa unification with mu < 0 is compatible with the current experimental bounds, including the WMAP bound on neutralino dark matter and the measured value of the muon anomalous magnetic moment. We present a variety of benchmark points which include relatively light squarks (~ TeV) of the first two families and an example in which the bottom and top squarks are lighter than the gluino. This is quite distinct from Yukawa unification with mu > 0 and universal gaugino masses in which the gluino is the lightest colored sparticle and the sqaurks of the first two families have masses in the multi-TeV range.

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arXiv2011

Muons from Neutralino Annihilations in the Sun: Flipped SU(5)

We consider two classes of supersymmetric flipped SU(5) models with gravity mediated supersymmetry breaking such that the thermal neutralino relic abundance provides the observed dark matter density in the universe. We estimate the muon flux induced by neutrinos that arise from neutralino annihilations in the Sun and discuss prospects for detecting this flux in the IceCube/Deep Core experiment. We also provide comparisons with the corresponding fluxes in the constrained minimal supersymmetric standard model and non-universal Higgs models. Regions in the parameter space that can be explored by the IceCube/DeepCore experiment are identified.

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arXiv2011

Light Stop from b-tau Yukawa Unification

We show that b-tau Yukawa unification can be successfully implemented in the constrained minimal supersymmetric model and it yields the stop co-annihilation scenario.The lightest supersymmetric particle is a bino-like dark matter neutralino, which is accompanied by a 10-20% heavier stop of mass ~ 100-330 GeV. We highlight some benchmark points which show a gluino with mass ~0.6 - 1.7 TeV, while the first two family squarks and all sleptons have masses in the multi- TeV range.

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arXiv2011

t-b-tau Yukawa unification for mu < 0 with a sub-TeV sparticle spectrum

We show compatibility with all known experimental constraints of t-b-tau Yukawa coupling unification in supersymmetric SU(4)_c x SU(2)_L x SU(2)_R which has non-universal gaugino masses and the MSSM parameter mu < 0. In particular, the relic neutralino abundance satisfies the WMAP bounds and Delta (g-2)_mu is in good agreement with the observations. We identify benchmark points for the sparticle spectra which can be tested at the LHC, including those associated with gluino and stau coannihilation channels, mixed bino-Higgsino state and the A-funnel region. We also briefly discuss prospects for testing Yukawa unification with the ongoing and planned direct detection experiments.

hep-ph↗

arXiv2010

Direct and Indirect Detection and LHC Signals of Bino-Higgsino Dark Matter

If the lightest dark matter neutralino has a sufficiently large Higgsino component, its spin-independent and spin-dependent cross sections on nucleons can be sizable enough to be detected soon in direct and indirect surveys. We outline in this paper some characteristic features expected of mixed bino-Higgsino dark matter. If the observed relic density is saturated by the bino-Higgsino dark matter, it fixes the amount of allowable bino-Higgsino mixing and provides predictions for other observables which can be tested at the Large Hadron Collider (LHC). We study the correlation between the cross sections and the branching ratio of B_s -> mu^+ mu^-. For a mixed bino-Higgsino dark matter, the mass differences of the neutralinos can be less than M_Z. This will cause an excess of lepton pairs, above the Standard Model predictions, from the decays of the two heavier neutralinos. We discuss implications of the dilepton invariant mass distribution, and outline a way to extract the neutralino parameters for testing gaugino mass unification and deducing the relic density from an interplay of astrophysical detection and LHC measurements.

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arXiv2010

New Fermions at the LHC and Mass of the Higgs Boson

Unification at M_{GUT}\sim 3\times 10^{16} GeV of the three Standard Model (SM) gauge couplings can be achieved by postulating the existence of a pair of vectorlike fermions carrying SM charges and masses of order 300 GeV -- 1 TeV. The presence of these fermions significantly modifies the vacuum stability and perturbativity bounds on the mass of the SM Higgs boson. The new vacuum stability bound in this extended SM is estimated to be 117 GeV, to be compared with the SM prediction of about 128 GeV. An upper bound of 190 GeV is obtained based on perturbativity arguments. The impact on these predictions of type I seesaw physics is also discussed. The discovery of a relatively `light' Higgs boson with mass \sim 117 GeV could signal the presence of new vectorlike fermions within reach of the LHC.

hep-ph↗

arXiv2010

Color Triplet Diquarks at the LHC

We consider a class of supersymmetric models containing baryon number violating processes such as observable neutron - antineutron oscillations that are mediated by color triplet diquark fields. For plausible values of the diquark-quark couplings, the scalar diquark with mass between a few hundred GeV and one TeV or so can be produced in the s-channel at the LHC and detected through its decay into a top quark and a hadronic jet.

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arXiv2009

CDMS II Inspired Neutralino Dark Matter in Flipped SU(5)

We investigate neutralino dark matter in supersymmetric flipped SU(5), focusing on candidates with masses of order 30 - 150 GeV and spin independent cross sections that are consistent with the most recent CDMS II results. We assume gravity mediated supersymmetry breaking and restrict the magnitude of the soft supersymmetry breaking mass parameters to 1 TeV or less. With non-universal soft gaugino and Higgs masses, and taking flipped SU(5) into account, we identify allowed regions of the parameter space and highlight some benchmark solutions including Higgs and sparticle spectroscopy.

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arXiv2009

Coannihilation Scenarios and Particle Spectroscopy in SU(4)_c x SU(2)_L x SU(2)_R

We identify a variety of coannihilation scenarios in a supersymmetric SU(4)_c x SU(2)_L x SU(2)_R model with discrete left-right symmetry. Non-universal gaugino masses, compatible with the gauge symmetry, play an essential role in realizing gluino and bino-wino coannihilation regions that are consistent with the WMAP dark matter constraints. We also explore regions of the parameter space in which the little hierarchy problem is partially resolved. We present several phenomenologically interesting benchmark points and the associated sparticle and Higgs mass spectra.

hep-ph↗

arXiv2009

Amelioration of Little Hierarchy Problem in SU(4)_c x SU(2)_L x SU(2)_R

The little hierarchy problem encountered in the constrained minimal supersymmetric model (CMSSM) can be ameliorated in supersymmetric models based on the gauge symmetry G_{422} \equiv SU(4)_c x SU(2)_L x SU(2)_R. The standard assumption in CMSSM (and in SU(5) and SO(10)) of universal gaugino masses can be relaxed in G_{422}, and this leads to a significant improvement in the degree of fine tuning required to implement radiative electroweak breaking in the presence of a characteristic supersymmetry breaking scale of around a TeV. Examples of Higgs and sparticle mass spectra realized with 10% fine tuning are presented.

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arXiv2009

Type II Seesaw and the PAMELA/ATIC Signals

We discuss how the cosmic ray signals reported by the PAMELA and ATIC/PPB-BETS experiments may be understood in a Standard Model (SM) framework supplemented by type II seesaw and a stable SM singlet scalar boson as dark matter. A particle physics explanation of the 'boost' factor can be provided by including an additional SM singlet scalar field.

hep-ph↗

arXiv2009

Yukawa Unification and Neutralino Dark Matter in SU(4)_c \times SU(2)_L \times SU(2)_R

We consider a left-right symmetric SU(4)_c \times SU(2)_L \times SU(2)_R (4-2-2) model with gravity mediated supersymmetry breaking. We find that with 4-2-2 compatible non-universal gaugino masses, t-b-τYukawa coupling unification is consistent with neutralino dark matter abundance and with constraints from collider experiments (except (g-2)_μ). The gluino mass lies close to that of the lightest neutralino, so that the gluino co-annihilation channel plays an important role in determining the neutralino relic abundance. By relaxing the Yukawa unification constraint we find stau and stop masses as low as 200-220 GeV. We highlight some benchmark points for these cases with 40 < \tanβ< 58.

hep-ph↗

arXiv2009

CMSSM Spectroscopy in light of PAMELA and ATIC

Dark matter neutralinos in the constrained minimal supersymmetric model (CMSSM) may account for the recent cosmic ray electron and positron observations reported by the PAMELA and ATIC experiments either through self annihilation or via decay. However, to achieve this, both scenarios require new physics beyond the 'standard' CMSSM, and a unified explanation of the two experiments suggests a neutralino mass of order 700 GeV - 2 TeV. A relatively light neutralino with mass around 100 GeV (300 GeV) can accomodate the PAMELA but not the ATIC observations based on a model of annihilating (decaying) neutralinos. We study the implications of these scenarios for Higgs and sparticle spectroscopy in the CMSSM and highlight some benchmark points. An estimate of neutrino flux expected from the annihilating and decaying neutralino scenarios is provided.

hep-ph↗

arXiv2008

Soft Probes of SU(5) Unification

We explore the sparticle and Higgs spectroscopy of an SU(5) inspired extension of the constrained minimal supersymmetric standard model (CMSSM). The universal soft parameter m_0 is replaced by m_{\bar 5} and m_{10}, where m_{\bar 5} and m_{10} denote universal soft scalar masses associated with fields in the five and ten dimensional representations of SU(5). The special case m_{\bar 5} << m_{10} yields a rather characteristic sparticle spectroscopy which can be tested at the LHC. We highlight a few benchmark points in which the lightest neutralino saturates the WMAP bound on cold dark matter abundance.

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arXiv2008

NMSSM and Seesaw Physics at LHC

We consider extensions of the next-to-minimal supersymmetric model (NMSSM) in which the observed neutrino masses are described in terms of effective dimension six (or seven) rather than dimension five operators. All such operators respect the discrete symmetries of the model. The new particles associated with the double (or triple) seesaw mechanism can have sizable couplings to the known leptons, even with a TeV seesaw scale. In the latter case some of these new short-lived particles could be produced and detected at the LHC.

hep-ph↗

arXiv2008

Higgs Boson Mass, Sparticle Spectrum and Little Hierarchy Problem in Extended MSSM

We investigate the impact of TeV-scale matter belonging to complete vectorlike multiplets of unified groups on the lightest Higgs boson in the MSSM. We find that consistent with perturbative unification and electroweak precision data the mass m_h can be as large as 160 GeV. These extended MSSM models can also render the little hierarchy problem less severe, but only for lower values of m_h < 125 GeV. We present estimates for the sparticle mass spectrum in these models.

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