arXiv subjects

Pran Nath

Publications and source records attributed to Pran Nath.

At least 181 records · Page 10Linked to original sources

arXiv2001

Complete Cubic and Quartic Couplings of 16 and $\bar {16}$ in SO(10) Unification

A recently derived basic theorem on the decomposition of SO(2N) vertices is used to obtain a complete analytic determination of all SO(10) invariant cubic superpotential couplings involving $16_{\pm}$ semispinors of SO(10) chirality $\pm$ and tensor representations. In addition to the superpotential couplings computed previously using the basic theorem involving the 10, 120 and $\bar{126}$ tensor representations we compute here couplings involving the 1, 45 and 210 dimensional tensor representations, i.e., we compute the $\bar{16}_{\mp}16_{\pm}1$,$\bar{16}_{\mp}16_{\pm}45$ and $\bar{16}_{\mp}16_{\pm}210$ Higgs couplings in the superpotential. A complete determination of dimension five operators in the superpotential arising from the mediation of the 1, 45 and 210 dimensional representations is also given. The vector couplings $\bar{16}_{\pm}16_{\pm}1$, $\bar{16}_{\pm}16_{\pm}45$ and $\bar{16}_{\pm}16_{\pm}210$ are also analyzed. The role of large tensor representations and the possible application of results derived here in model building are discussed.

hep-th↗

arXiv2001

Muon g-2 and Implications for Supersymmetry

A brief review is given of the implications of the recent Brookhaven result on the muon anomaly ($a_μ$) for supersymmetry. We focus mainly on the implications of the recent results for the minimal supergravity unified model. We show that the observed difference implies the existence of sparticles most of which should become observable at the Large Hadron Collider. Further, as foreseen in works prior to the Brookhaven experiment the sign of the difference between experimental prediction of $a_μ$ and its Standard Model value determines the sign of the Higgs mixing parameter $μ$. The $μ$ sign has important implications for the direct detection of dark matter. Implications of the Brookhaven result for other low energy phenomena are also discussed.

hep-ph↗

arXiv2001

Large Phases and CP Violation in SUSY

A brief overview is given of recent developments in the analyses of large phases and CP violation in supersymmetric unified models. The problem of experimental electric dipole moment constraints and large phases is discussed. Implications of large phases on supersymmetric phenomena are reviewed. The possibility of generating a muon electric dipole moment much larger than implied by the scaling relation $d_μ/d_e\simeq m_μ/m_e$ from lepton flavor nonuniversality and within reach of the recently proposed Brookhaven experiment for a sensitive probe of $d_μ$ is also discussed.

hep-ph↗

arXiv2001

Gaugino Mass Nonuniversality and Dark Matter in SUGRA, Strings and D Brane Models

The effects of nonuniversality of gaugino masses on dark matter are examined within supersymmetric grand unification, and in string and D brane models with R parity invariance. In SU(5) unified models nonuniversality in the gaugino sector can be generated via the gauge kinetic energy function which may depend on the 24, 75 and 200 dimensional Higgs representations. We also consider string models which allow for nonuniversality of gaugino masses and D brane models where nonuniversality arises from embeddings of the Standard Model gauge group on five branes and nine branes. It is found that with gaugino mass nonuniversality the range of the LSP mass can be extended much beyond the range allowed in the universal SUGRA case, up to about 600 GeV even without coannihilation effects in some regions of the parameter space. The effects of coannihilation are not considered and inclusion of these effects may further increase the allowed neutralino mass range. Similarly with the inclusion of gaugino mass nonuniversality, the neutralino-proton ($χ-p$) cross-section can increase by as much as a factor of 10 in some of regions of the parameter space. An analysis of the uncertainties in the quark density content of the nucleon is given and their effects on $χ-p$ cross-section are discussed. The predictions of our analysis including nonuniversality is compared with the current limits from dark matter detectors and implications for future dark matter searches are discussed.

hep-ph↗

arXiv2001

Upper Limits on Sparticle Masses from g-2 and the Possibility for Discovery of Supersymmetry at Colliders and in Dark Matter Searches

We analyze the implications of the new physics effect seen in the $g-2$ Brookhaven measurement and show that if the effect arises from supersymmetry, then the sign of the Higgs mixing parameter $μ$ is determined to be positive in the standard sign convention. Further, analyses within the minimal supergravity model show that the Brookhaven result leads to upper limits on the universal gaugino and scalar masses of $m_{1/2}\leq 800$ GeV and $m_0\leq 1.5$ TeV for $\tanβ\leq 55$. Our analysis strongly suggests that supersymmetry via production of sparticles must be found at the Large Hadron Collider. Further, sign($μ$) positive is favorable for the discovery of supersymmetric cold dark matter.

hep-ph↗

arXiv2001

Probe of SUSY and Extra Dimensions by the Brookhaven g-2 Experiment

A brief review is given of $a_μ=(g_μ-2)/2$ as a probe of supersymmetry and of extra dimensions. It is known since the early to mid nineteen eightees that the supersymmetric electro-weak correction to $a_μ$ can be as large or larger than the Standard Model electro-weak correction and thus any experiment that proposes to test the Standard Model electro-weak correction will also test the supersymmetric correction and constrain supersymmetric models. The new physics effect seen in the Brookhaven (BNL) experiment is consistent with these early expectations. Detailed analyses within the well motivated supergravity unified model show that the size of the observed difference ($a_μ^{exp}-a_μ^{SM}$) seen at Brookhaven implies upper limits on sparticle masses in a mass range accessible to the direct observation of these particles at the Large Hadron Collider. Further, analyses also show that the BNL data is favorable for the detection of supersymmeteric dark matter in direct dark matter searches. The effect of large extra dimensions on $a_μ$ is also discussed. It is shown that with the current limits on the size of extra dimensions, which imply that the inverse size of such dimensions lies in the TeV region, their effects on $a_μ$ relative to the supersymmetric contribution is small and thus extra dimensions do not produce a serious background to the supersymmetric contribution. It is concluded that the analysis of the additional data currently underway at Brookhaven as well as a reduction of the hadronic error will help pin down the scale of weak scale supersymmetry even more precisely.

hep-ph↗

arXiv2001

Slepton Flavor Nonuniversality, the Muon EDM and its Proposed sensitive Search at Brookhaven

We analyze the electric dipole moment of the electron ($d_e$), of the neutron ($d_n$) and of the muon ($d_μ$) using the cancellation mechanism in the presence of nonuniversalities of the soft breaking parameters. It is shown that the nonuniversalities in the slepton sector produce a strong violation of the scaling relation $d_μ/d_e\simeq m_μ/m_e$ in the cancellation region. An analysis of $d_e, d_n$ and $d_μ$ under the constraints of the current experimental limits on $d_e$ and $d_n$ and under the constraints of the recent Brookhaven result on $g_μ-2$ shows that in the non-scaling region $d_μ$ can be as large as ($10^{-24}-10^{-23}$)ecm and thus within reach of the recently proposed Brookhaven experiment for a sensitive search for $d_μ$ at the level of $10^{-24}$ ecm.

hep-ph↗

arXiv2001

Analysis of Couplings with Large Tensor Representations in SO(2N) and Proton Decay

We develop techniques for the analysis of SO(2N) invariant couplings which allow a full exhibition of the SU(N) invariant content of the spinor and tensor representations. The technique utilizes a basis consisting of a specific set of reducible SU(N) tensors in terms of which the SO(2N) invariant couplings have a simple expansion. The technique is specially useful for couplings involving large tensor representations. We exhibit the technique by performing a complete determination of the trilinear couplings in the superpotential for the case of SO(10) involving the 16 plet of matter, i.e., we give a full determination of the ${16-16-10_s}$, ${16-16-120_a}$ and ${16-16-\bar{126}_s}$ couplings. The possible role of large tensor representations in the generation of quark lepton textures is discussed. It is shown that the couplings involving $\bar{126}$ dimensional representation generate extra zeros in the Higgs triplet textures which can lead to an enhancement of the proton decay lifetime by a factor of $10^3$. These results also have implications for neutrino mass textures.

hep-ph↗

arXiv2001

Constraints on Explicit CP Violation from the Brookhaven Muon g-2 Experiment

We use the recently derived CP phase dependent analytic results for the supersymmetric electro-weak correction to $g_μ-2$ to constrain the explicit CP phases in softly broken supersymmetry using the new physics effect seen in the g-2 Brookhaven measurement. It is shown that the BNL data strongly constrains the CP violating phase $θ_μ$ (the phase of the Higgs mixing parameter $μ$) and $ξ_2$ (the phase of the SU(2) gaugino mass $\tilde m_2$) and as much as 60-90% of the region in the $ξ_2-θ_μ$ plane is eliminated over a significant region of the MSSM parameter space by the BNL constraint. The region of CP phases not excluded by the BNL experiment allows for large phases and for a satisfaction of the EDM constraints via the cancellation mechanism. We find several models with large CP violation which satisfy the EDM constraint via the cancellation mechanism and produce an $a_μ^{SUSY}$ consistent with the new physics signal seen by the Brookhaven experiment. The sparticle spectrum of these models lies within reach of the planned accelerator experiments.

hep-ph↗

arXiv2001

Supergravity Unification

A review is given of the historical developments of 1982 that lead to the supergravity unified model (SUGRA)with gravity mediated breaking of supersymmetry. Further developments and applications of the model in the period 1982-85 are also discussed. The supergravity unified model and its minimal version (mSUGRA) are currently among the leading candidates for physics beyond the Standard Model. A brief note on the developments from the present vantage point is included.

hep-ph↗

arXiv2000

Physics From Extra Dimensions

A brief review of the recent developments in the physics from extra dimensions is given with a focus on the effects of Kaluza-Klein excitations in the Standard Model sector. It is shown that the current accurate data on the Fermi constant and on other electro-weak parameters puts a lower bound on the scale of extra dimensions of $\sim$ 3 TeV, and thus the observation of such dimensions lies beyond the reach of accelerators in the near future. The correction to the anomalous magnetic moment of the muon from extra dimensions is discussed and one finds that with the current limit on the scale of extra dimensions from the Fermi constant, the correction to $g_μ-2$ does not compete with the potentially large contributions from the supersymmetric electro-weak correction. The possibility of generating Kaluza-Klein excitations associated with large radius compactifications at the LHC is discussed. It is shown that if such excitations are indeed produced their resonance structure will encode information on the number of compactified dimensions as well as on the nature of the specific orbifold compactification. A brief discussion of difficulties such as rapid proton decay that one encounters in theories with large radius compactifications is given.

hep-ph↗

arXiv2000

Recent Developments in Supersymmetric Dark Matter

A brief review is given of some of the recent developments in the theoretical analyses of supersymmetric dark matter. These include the effects of uncertainties in the wimp velocity and wimp density and of the effects of uncertainties in the quark densities of the proton. Also analyzed are the effects of non-universalities in the gaugino sector and their effects on determining the nature of cold dark matter, i.e., if the neutralino is bino like, higgsino like, or wino like. The maximum and the minimum elastic neutralino proton cross sections are discussed and a comparison of the direct and the indirect detection arising from the capture and annihilation of neutralinos in the core of the earth and the sun is given. Some of the other recent developments are summarized.

hep-ph↗

arXiv2000

Corrections to the Higgs Boson Masses and Mixings from Chargino, W and Charged Higgs Exchange Loops and Large CP Phases

One loop contributions to the Higgs boson masses and mixings from the chargino sector consisting of the chargino, the W, and the charged Higgs boson ($χ^+-W-H^+$) exchanges and including the effects of large CP violating phases are computed. It is found that the chargino sector makes a large contribution to the mixings of the CP even and the CP odd Higgs sectors through the induced one loop effects and may even dominate the mixing generated by the stop and the sbottom sectors. Effects of the chargino sector contribution to the Higgs boson masses are also computed. It is found that the sum of the $χ^+-W-H^+$ exchange contribution lowers the lightest Higgs boson mass and worsens the fine tuning problem implied by the LEP data. Phenomenological implications of these results are discussed.

hep-ph↗

arXiv2000

Effects of Large CP Phases on the Proton Lifetime in Supersymmetric Unification

The effects of large CP violating phases arising from the soft SUSY breaking parameters on the proton lifetime are investigated in supersymmetric grand unified models. It is found that the CP violating phases can reduce as well as enhance the proton lifetime depending on the part of the parameter space one is in. Modifications of the proton lifetime by as much as a factor of 2 due to the effects of the CP violating phases are seen. The largest effects arise for the lightest sparticle spectrum in the dressing loop integrals and the effects decrease with the increasing scale of the sparticle masses. An analysis of the uncertainties in the determination of the proton life time due to uncertainties in the quark masses and in the other input data is also given. These results are of import in the precision predictions of the proton lifetime in supersymmetric unification both in GUT and in string models when the soft SUSY breaking parameters are complex.

hep-ph↗

arXiv2000

SUSY Dark Matter

Several new effects have been investigated in recent analyses of supersymmetric dark matter. These include the effects of the uncertainties of wimp velocity distributions, of the uncertainties of quark densities, of large CP violating phases, of nonuniversalities of the soft SUSY breaking parameters at the unification scale and of coannihilation on supersymmetric dark matter. We review here some of these with emphasis on the effects of nonuniversalities of the gaugino masses at the unification scale on the neutralino-proton cross-section from scalar interactions. The review encompasses several models where gaugino mass nonuniversalities occur including SUGRA models and D brane models. One finds that gaugino mass nonuniversalities can increase the scalar cross-sections by as much as a factor of 10 and also significantly extend the allowed range of the neutralino mass consistent with constraints up to about 500 GeV. These results have important implications for the search for supersymmetric dark matter.

hep-ph↗

arXiv2000

CP Violation and Dark Matter

A brief review is given of the effects of CP violation on the direct detection of neutralinos in dark matter detectors. We first summarize the current developments using the cancellation mechanism which allows for the existence of large CP violating phases consistent with experimental limits on the electron and on the neutron electric dipole moments in a broad class of SUSY, string and D brane models. We then discuss their effects on the scattering of neutralinos from quarks and on the event rates. It is found that while CP effects on the event rates can be enormous such effects are reduced significantly with the imposition of the EDM constraints. However, even with the inclusion of the EDM constraints the effects are still very significant and should be included in a precision prediction of event rates in any SUSY, string or D brane model.

hep-ph↗

arXiv2000

Large CP Phases and the Cancellation Mechanism in EDMs in SUSY, String and Brane Models

We show that EDMs obey a simple approximate scaling under the transformation $m_0\to λm_0,m_{1/2}\to λm_{1/2}$ in the large $μ$ region when $μ$ itself obeys the same scaling, ie., $μ\to λμ$. In the scaling region the knowledge of a single point in the MSSM parameter space where the cancellation in the EDMs occur allows one to generate a trajectory in the $m_0-m_{1/2}$ plane where the cancellation mechanism holds and the EDMs are small. We illustrate these results for MSSM with radiative electro-weak symmetry breaking constraints. We also discuss a class of D brane models based on Type IIB superstring compactifications which have non-universal phases in the gaugino mass sector and allow large CP violating phases consistent with the EDM constraints through the cancellation mechanism. The scaling in these D brane models and in a heterotic string model is also discussed.

hep-ph↗

arXiv2000

CP Violation and the Muon Anomaly in N=1 Supergravity

The one loop supersymmetric electro-weak correction to the anomalous magnetic moment of the muon is derived in the minimal N=1 supergravity unification with two CP violating phases. A numerical analysis of the CP violating effects on $g_μ-2$ is carried out with the cancellation mechanism to guarantee the satisfaction of the experimental limits on the electric dipole moments of the electron and on the neutron. It is found that the effects of the CP phases can significantly affect the supersymmetric electro-weak correction to $g_μ-2$, and that the numerical size of such a correction can be as large or larger than the Standard Model electro-weak correction to $g_μ-2$. These results are of import for the new Brookhaven experiment which is expected to increase the sensitivity of the $g_μ-2$ measurements by a factor of 20 and allow for a test of the electro-weak correction in the near future.

hep-ph↗