Supersymmetric Left-right Model Research Articles

Supersymmetric solution to CP problems.

We analyze the minimal supersymmetric left-right model with non-re\-nor\-malizable interactions induced by higher scale physics and study its {\it CP} violating properties. We show that it: (i) solves the strong {\it CP} problem; (ii) predicts the neutron electric dipole moment well within experimental limits (thus solving the usual SUSY {\it CP} problem). In addition, it automatically conserves {\it R}-parity. The key points are that the parity symmetry forces the Yukawa couplings to be hermitean, while supersymmetry ensures that the scalar potential has a minimum with real higgs doublet vacuum expectation values. Gluino and B-L gaugino masses are automatically real. The observed {\it CP} violation in the kaon system comes, as in the Standard Model, from the Kobayashi-Maskawa-type phases. These solutions are valid for any value of the right-handed breaking scale $M_R$, as long as the effective theory below $M_R$ has only two Higgs doublets that couple fully to fermions. ({\it i.e.} the theory below $M_R$ is MSSM-like.) The potentially dangerous $SU(2)_L$ gaugino one-loop contributions to $\bar{\Theta}$ below $M_R$ can be avoided if the left-right symmetry originates from a unified theory in which the $SU(2)_{L,R}$ gaugino masses are real. As an example, we show how the left-right symmetry can be embedded in an SO(10) theory.

PROBING CHARGINO-NEUTRALINO PRODUCTION AT THE FERMILAB TEVATRON COLLIDER IN A SUPERSYMMETRIC LEFT-RIGHT MODEL

We study production of chargino-neutralino through the process [Formula: see text] at the Fermilab Tevatron collider [Formula: see text] within the framework of the left-right supersymmetric model. We investigate various regions of parameter space accessible through a clean isolated trilepton signals from [Formula: see text] production for which the standard model background is expected to be tiny.

Simple supersymmetric solution to the strong CP problem.

It is shown that the minimal supersymmetric left-right model can provide a natural solution to the strong {\it CP} problem without the need for an axion, nor any additional symmetries beyond supersymmetry and parity.

Solution to the strong CP problem: Supersymmetry with parity.

We find that supersymmetry with parity can solve the strong CP problem in many cases including the interesting cases of having the minimal supersymmetric standard model or some of its extensions below the Planck, grand unified theory, and intermediate scales, as well as for the case where we have a low-energy supersymmetric left-right model. Predictions emerge for some of the CP violating phases in these supersymmetric models.

Signals of left-right supersymmetry in e + e - collisions

We study chargino and neutralino pair production at the Next Linear e+ e− Collider in a supersymmetric left-right model. We investigate on- and off-resonance signals via the processes: $e^{+}e^{-}⌝ghtarrow {⇔lde chi}_{1}^{+}{⇔lde chi}_{1}^{-} ⌝ghtarrow e^{+}e^{-}+{⤪ p}_{⤪ miss}$ and $e^{+}e^{-}⌝ghtarrow {⇔lde chi}_{2}^{0}{⇔lde chi}_{1}^{0} ⌝ghtarrow e^{+}e^{-}+{⤪ p}_{⤪ miss}$. These reactions could lead to observable signals as they compare with the background signal from W± -pair production.

Upper bound on the WR mass in automatically R-conserving supersymmetric models.

We show that in automatically $R$-conserving minimal supersymmetric (SUSY) left-right symmetric models there is a theoretical upper limit on the mass of the right-handed ${W}_{R}$ boson given by ${M}_{{W}_{R}}\ensuremath{\le}\frac{g{M}_{\mathrm{SUSY}}}{f}$, where ${M}_{\mathrm{SUSY}}$ is the scale of SUSY breaking, $g$ the weak gauge coupling, and $f$ the Yukawa coupling responsible for generating the right-handed neutrino masses. If ${M}_{{W}_{R}}$ violates the above bound, the ground state of the theory breaks electromagnetism. The only way to avoid this bound while keeping the theory automatically $R$ conserving is to expand the theory to include very specific kinds of additional multiplets.

Predictions of the top quark mass in the minimal supersymmetric left-right model.

The one-loop evolution of Yukawa couplings in the minimal supersymmetric left-right (MSUSYLR) model with a wide variation of the right-handed breaking scale {ital M}{sub {ital R}} from 1 TeV to 10{sup 18} GeV is studied assuming that all third generation Yukawa couplings are equal and in the fixed point domain of the top quark Yukawa coupling ({ital h}{sub {ital t}}) at the Planck scale. We show that (1) the top quark Yukawa coupling {ital h}{sub {ital t}} displays a fixed point behavior that is similar to that of the minimal supersymmetric standard model, (2) the MSUSYLR model predicts a value of the top quark mass in the interval 177 to 184 GeV for {alpha}{sub {ital s}} in the interval 0.11 to 0.12, (3) a large value of tan{beta} is required to reproduce the correct mass of the bottom quark and {tau} lepton, (4) with the experimental value of the ratio {ital m}{sub {ital b}}({ital m}{sub {ital b}})/{ital m}{sub {tau}}({ital m}{sub {tau}}) as an input the range of the right-handed symmetry-breaking scale {ital M}{sub {ital R}} can be predicted, and (5) the numerical value of the Majorana Yukawa coupling {ital h}{sub {ital M}} can be calculated which is otherwise a completelymore » free parameter.« less

Signatures of light neutralinos in theZ R 0 -decay in a supersymmetric left-right model

Decays and branching ratios of light neutralino production in\(Z_R^0 \to \tilde \chi _i^0 \tilde \chi _j^0 \) in the left-right super-symmetric model are considered. We study in detail the signatures of one and two sided events in\(Z_R^0 \to \tilde \chi _1^0 \tilde \chi _2^0 \) and\(Z_R^0 \to \tilde \chi _2^0 \tilde \chi _2^0 \) respectively, and their dependence on the parameters of the light neutralino mixing matrix.

Production of chargino and neutralino pairs at the CDF in a supersymmetric left-right model

Production of chargino and neutralino pairs in a supersymmetric left-right model is studied at the Tevatron collider (CDF) ( square root s=1.8 TeV). Signals of the cross sections of the processes pp to chi 1+ chi 1- and pp to chi 20 chi 10+X, followed by the decays chi 1+or- to l+or- nu e chi 10 and chi 20 to l+l- chi 10, are considered in the various regions of dilepton transverse momentum, pt.

The higgs sector of a supersymmetric left-right model

We study the symmetry breaking sector of a supersymmetric left-right model based on the gauge group SU(2) l × SU(2) r × U(1) b- l . The explicit mass matrices of neutral, singly charged and doubly charged scalars are constructed. In the minimum the R-parity is found to be spontaneously broken. An experimentally interesting feature of the model is that one of the doubly charged scalars is possibly light enough to be seen in the next linear collider.

Signatures of charginos in the Z R0-decay in the left-right supersymmetric model

Decay rates and branching ratios for production of charginos in Z R 0 → X ̃ i + X ̃ j − in the left-right supersymmetric model are considered. We study in detail the signatures of two-sided events in Z R 0 → X ̃ 1 + X ̃ 1 − and their dependence on the parameters of the chargino mixing matrix.

Supersymmetric left-right model and its tests in linear colliders

We investigate phenomenological implications of a supersymmetric left-right model based on SU(2) L × SU(2) R × U(1) B– L gauge symmetry testable in the next generation linear colliders. We concentrate in particular on the doubly charged SU(2) R triplet higgsino Δ , which we find very suitable for experimental search. We estimate its production rate in e +e −, e −e −, e −γ and γγ collisions and consider its subsequent decays. These processes have a clear discovery signature with a very low background from other processes.

Slepton pair production in e+e− collision in supersymmetric left-right model

The pair production of sleptons in electron-positron collisions is investigated in a supersymmetric left-right model. The cross section is found considerably larger than in the minimal supersymmetric version of the Standard Model (MSSM) because of more contributing graphs. A novel process is a doubly charged higgsino exchange in u-channel, which makes the angular distribution of the final state particles and the final state asymmetries to differ from those of the MSSM. It also allows for the flavour non-diagonal final states $\tilde e\tilde\mu$, $\tilde e\tilde\tau$ and $\tilde \mu\tilde\tau$, forbidden in the MSSM. These processes also give indirect information about neutrino mixings since they depend on the same couplings as the Majorana mass terms of the right-handed neutrinos.

SEARCH FOR CHARGINO AND NEUTRALINO PRODUCTION AT THE LHC IN THE LEFT-RIGHT SUPERSYMMETRIC MODEL

An extension of the supersymmetric Standard Model to the left-right supersymmetric model (L-R SUSY), SU (2) L × SU (2) R × U (1)B-L, is considered. We investigate the possibility of detecting chargino and neutralino production at the LHC [Formula: see text] through the process [Formula: see text]. A numerical analysis is presented for the chargino mass [Formula: see text] neutralino mass [Formula: see text] and tan θκ = 1.6. Based on reasonable assumptions on W R , and assuming g L ≃ g R ≃ g, we take MW R = 1 TeV . The results are compared with the conventional background signal of the process [Formula: see text].

Masses of charginos and neutralinos in a left-right supersymmetric model

We consider chargino and neutralino masses in an extension of the supersymmetric standard model to the supersymmetricSU(2) L ×SU(2) R ×U(1) B-L model. After mixing of gauginos with higgsinos in addition to four charginos there are three neutralinos generated from the first symmetry breaking, and four neutralinos generated from the second symmetry breaking. In the minimal supersymmetry and left-right supersymmetry models, these mixings can be parameterized in terms of a few parameters. We find analytical expressions and numerical solutions for the mass eigenstates with some restrictions on theL-R parameters.

No parity violation without R-parity violation.

In a class of supersymmetric left-right models (SUSYLR) of weak interactions where R-parity is automatically conserved, we show that spontaneous breakdown of parity CANNOT occur without spontaneous breakdown of R-parity. This intriguing result connects two physically different scales in supersymmetric models.

Chargino-neutralino production in $$p\bar p$$ -collisions for the left-right supersymmetric model

An extension of the supersymmetric standard model to the supersymmetric SU(2)$\sb{\rm L}$ x SU(2)$\sb{\rm R}$ x U(1)$\sb{\rm B-L}$ model is considered. The gauge group contains bi-doublet and triplet Higgs fields. In this work we have considered chargino (charged gauginos mixed with higgsinos) and neutralino (neutral gauginos mixed with higgsinos) eigenstates for the left-right supersymmetric (L-R SUSY) model. After mixing, in the minimal supersymmetric model (MSSM), there are two charginos and four neutralinos. In the L-R supersymmetric model, in addition to four charginos there are three neutralinos generated from the first symmetry breaking, and four neutralinos generates from the second symmetry breaking. The mixings are in general model dependent. In the minimal SUSY and L-R SUSY models, these mixings can be parameterized in terms of a few parameters. We find analytical expressions and numerical solutions for the mass eigenstates with some restrictions on the L-R parameters. We also investigate the possibility of detecting chargino and neutralino production in pp-collisions at CDF, namely $\rm p\bar{p}\to W\sbsp{L,R}{-} + X\to\ \sbsp{\chi\sb{j}}{\sim\sb-}\sbsp{\chi\sb{i}}{\sim0} + X.$ The expressions for these inclusive cross-sections are solved numerically, using parton model distributions. We have used $\rm \tilde{M}\sb\chi -= 45\ GeV,$ tan$\beta$ = 1 and a lower bound on the lightest supersymmetric particle (LSP) mass, $\tilde\chi$ = 14 GeV. Finally we take $\rm M\sb{WR}\ge 300$ GeV for $\rm g\simeq g\sb{L}\simeq g\sb{R}.$ In the pp-center of mass frame we find the cross sections are: $\rm \sigma\sb{L}(p\bar{p}\to W\sbsp{L}{-} + X\to\sbsp{\chi\sb{j}}{\sim\sb-}\sbsp{\chi\sb{i}}{\sim0} + X)\approx0.11$ nb, and $\rm \sigma\sb{R}(p\bar{p}\to W\sbsp{R}{-} + X\to\sbsp{\chi\sb{j}}{\sim\sb-}\sbsp{\chi\sb{i}}{\sim0} + X)\approx4.6$ pb, and thus $\rm \sigma\sb{L}\ge24\sigma\sb{R}$ at $\sqrt{\rm s}$ = 1.8 TeV. Cross sections are also given for larger values of the center of mass energy $\sqrt{\rm s}$ up to those available at the SSC. The results are compared with the prompt-lepton background of the $\rm W\sbsp{L,R}{-}$ decays from $\rm p\bar{p}\to W\sbsp{L,R}{-} + X\to\ell\sp-\nu\sb{\ell L,R} + X.$ Both decays for $\rm W\sbsp{L,R}{-}$-bosons show Jacobian peaks for $\rm p\sb{T} = \sqrt{\{s}}/2\simeq M\sb{WL}/2\simeq40$ GeV $\rm (p\sb{T}\simeq 150$ GeV for M$\sb{\rm WR})$ at $\theta=90\sp\circ.$ Furthermore the chargino signature unlike the prompt-lepton background is symmetric under the Jacobian peak. We also exhibit the dependence of the angular distribution of the chargino on the c.m angle $\theta$ for $\rm p\sb{T} = 40$ GeV, 150 GeV at $\sqrt{\rm s} = 1.8$ TeV.

Implications of the lepton-Higgs-boson generation symmetry in a supersymmetric left-right gauge model.

Some remarkable issues are investigated concerning an unconventional type of supersymmetric left-right gauge model, where the fields with different lepton numbers are accommodated together in the ${\mathrm{SU}(2)}_{R}$ multiplets. The phenomenology of the model is restricted by the generation symmetry in the lepton-Higgs-boson sector which is required to suppress enough the flavor-changing neutral currents mediated by the Higgs fields. The mass matrix of the neutralinos, in particular, has a certain form depending on the possible choices of the generation symmetry. The lightest state ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{N}}_{\mathrm{LSP}}$ is then found to consist almost entirely of the ${\mathrm{SU}(2)}_{L}\ifmmode\times\else\texttimes\fi{}{(\mathrm{U})1}_{Y}$-singlet neutralinos which form the ${\mathrm{SU}(2)}_{R}$ doublets together with the right-handed charged leptons. ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{N}}_{\mathrm{LSP}}$ acquires a mass at most \ensuremath{\sim} 1 GeV or even much smaller for most choices of the generation symmetry. It hence may be identified with the lightest supersymmetric particle. Some stringent constraints on the model are obtained from the astrophysical and cosmological effects of such an ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{N}}_{\mathrm{LSP}}$. The decays of superparticles would also look somewhat different, where ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{N}}_{\mathrm{LSP}}$ is produced in the final state.

Aspects of a supersymmetric left-right gauge model with tau-gaugino mixing.

A supersymmetric left-right gauge model is investigated, where the mixing between $\ensuremath{\tau}$ and the ${\mathrm{SU}(2)}_{R}$ gaugino ${\ensuremath{\chi}}_{R}$ occurs due to an unconventional assignment for the matter fields. At present, a small nonzero value may be allowed for the left-handed $\ensuremath{\tau}\ensuremath{-}{\ensuremath{\chi}}_{R}$ mixing angle, as suggested from the somewhat long lifetime of $\ensuremath{\tau}$, while the right-handed mixing angle is rather elusive in low-energy phenomena. Some constraints on the model parameters such as the $\ensuremath{\tau}\ensuremath{-}{\ensuremath{\chi}}_{R}$ mixing angles and the top-quark mass are obtained from the analysis of the $\ensuremath{\tau}\ensuremath{-}{\ensuremath{\chi}}_{R}$ mass matrix together with the perturbation condition on the Yukawa couplings at large scales. The rates of gauge-boson decays into lepton pairs are estimated for the allowed region of the model parameters. The results suggest that the $\ensuremath{\tau}\ensuremath{-}{\ensuremath{\chi}}_{R}$ mixing effects will be checked more clearly as the violation of lepton universality in the gauge-boson decays.

τ-gaugino mixing in a supersymmetric left-right gauge model

We investigate the mixing between a τ and an SU(2) R gaugino in a supersymmetric left-right gauge model. This mixing violates the universality between e-μ and τ. An appreciable amount of mixing can be obtained for a range of model parameters, which might explain the somewhat large lifetime of τ observed in the experiments. The effects of τ-gaugino mixing would also be seen in e +e −→ τ + τ −, in particular, at the Z pole.