[Paper Review] SO(10) inspired GMSB

Manuel E. Krauss, W. Porod+1 more|arXiv (Cornell University)|Apr 2, 2013

Particle physics theoretical and experimental studies3 citations

TL;DR

This paper proposes an SO(10)-inspired supersymmetric model with SU(3)×SU(2)×U(1)R×U(1)B-L gauge symmetry, embedded in minimal gauge mediation and incorporating an inverse seesaw mechanism for neutrinos. It shows that D-terms from the extended gauge sector significantly raise the light Higgs mass, enabling m_h ≈ 125 GeV without requiring superpartner masses to be extremely heavy, while predicting a diphoton Higgs decay rate consistent with or below the Standard Model expectation.

ABSTRACT

We consider a supersymmetric model motivated by a SO(10) GUT theory: the gauge sector near the SUSY scale consists of SU(3)_c x SU(2)_L x U(1)_R x U(1)_{B-L}. We embed this model in minimal gauge mediation and incorporate neutrino data via an inverse seesaw mechanism. Also in this restricted model the additional D-terms can rise the light Higgs mass in a sizable way. Therefore, it is much easier to obtain m_h \simeq 125 GeV without the need to push the SUSY spectrum to extremely large values as it happens in models with MSSM particle content only. We show that this model predicts a diphoton rate of the Higgs equal or smaller than the standard model expectation. We discuss briefly the collider phenomenology with a particular focus on the next to lightest supersymmetric particle where this model offers the sneutrino as an additional possiblity. Moreover we point out that also in this model variant supersymmetry can be discovered in Z' decays even in scenarios where the strongly interacting particles are too heavy to be produced at a sizable rate at LHC with 14 TeV. In addition, we show that lepton flavor violating observables constrain the size of the neutrino Yukawa couplings where in particular muon decays and \mu-e conversion in heavy atoms are of particular importance. Once these constraints are fullfilled the rates for au decays are predicted to be below the reach of near future experiments.

Motivation & Objective

• To construct a supersymmetric model motivated by SO(10) grand unification that incorporates realistic neutrino masses via the inverse seesaw mechanism.
• To explore whether additional D-terms from an extended gauge sector can raise the light Higgs mass, reducing the need for heavy superpartners to achieve m_h ≈ 125 GeV.
• To analyze the collider phenomenology, particularly the next-to-lightest supersymmetric particle (NLSP), with a focus on the sneutrino as a viable NLSP candidate.
• To assess the viability of discovering supersymmetry via Z' boson decays even when strongly interacting superpartners are too heavy for LHC production at 14 TeV.
• To constrain neutrino Yukawa couplings using lepton flavor violating processes, especially μ→eγ and μ-e conversion in atoms.

Proposed method

• Embedding the SU(3)×SU(2)×U(1)R×U(1)B-L gauge sector in minimal gauge mediation (GMSB), ensuring anomaly cancellation and natural gaugino mass generation.
• Implementing the inverse seesaw mechanism through heavy right-handed neutrinos to generate small neutrino masses consistent with oscillation data.
• Calculating radiative corrections to the Higgs mass, particularly from D-terms associated with the U(1)R and U(1)B-L symmetries, to enhance m_h.
• Evaluating the diphoton Higgs decay rate by computing loop corrections involving charginos and neutralinos in the extended spectrum.
• Analyzing the NLSP sector, identifying the sneutrino as a viable candidate due to its gauge quantum numbers and decay patterns.
• Assessing the reach of future experiments for μ→eγ and other LFV processes by constraining neutrino Yukawa couplings from existing bounds on μ→eγ and μ-e conversion in nuclei.

Experimental results

Research questions

• RQ1 Can the inclusion of U(1)R and U(1)B-L gauge symmetries in a GMSB framework significantly raise the light Higgs mass without requiring superpartner masses to be extremely large?
• RQ2 What is the predicted diphoton decay rate of the Higgs boson in this extended GMSB model, and how does it compare to the Standard Model expectation?
• RQ3 Can the sneutrino serve as a viable next-to-lightest supersymmetric particle (NLSP) in this model, and what are its phenomenological signatures?
• RQ4 Is it possible to discover supersymmetry via Z' boson decays even when the strongly interacting superpartners are too heavy for direct production at the LHC?
• RQ5 To what extent do lepton flavor violating observables constrain the neutrino Yukawa couplings in this model, and what are the implications for future searches of μ→eγ?

Key findings

• The D-terms from the extended U(1)R and U(1)B-L gauge symmetries significantly raise the light Higgs mass, enabling m_h ≈ 125 GeV without requiring superpartner masses to be pushed to extreme values.
• The model predicts a diphoton Higgs decay rate that is equal to or smaller than the Standard Model expectation, due to cancellations in chargino and neutralino loop contributions.
• The sneutrino emerges as a viable next-to-lightest supersymmetric particle (NLSP), offering distinct collider signatures distinct from the gravitino or other NLSPs.
• Supersymmetry can still be discovered via Z' decays into supersymmetric final states even when the strongly interacting superpartners are too heavy for direct LHC production at 14 TeV.
• Lepton flavor violating observables, particularly μ→eγ and μ-e conversion in heavy atoms, impose strong constraints on the neutrino Yukawa couplings, pushing the predicted μ→eγ branching ratio below the sensitivity reach of near-future experiments.