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R. Arnowitt

Publications and source records attributed to R. Arnowitt.

At least 55 records · Page 3Linked to original sources
arXiv2000

Dark Matter in Supergravity

We consider neutralino-proton cross sections for halo dark matter neutralinos within the framework of supergravity models with R-parity invariance for models with universal soft breaking (mSUGRA) and models with nonuniversal soft breaking. The analysis includes the necessary corrections to treat the large tanbeta region (i.e. L-R mixing in the squark and slepton mass matrices, loop corrections to the b and tau masses,etc) and includes all coannihilation phenomena. For mSUGRA, dark matter detectors with current sensitivity are seen to be probing the region where tanbeta>~25, Omega h^2 <0.1, m_{chi_1^0}~<90 GeV, and for the light Higgs, m_h~< 120 GeV. Nonuniversal models can have a much larger cross section, and current detectors can probe part of the parameter space where tan>~4. Minimum cross sections are generally greater than 10^{-9} pb to 10^{-10} pb for m_{1/2} <600 GeV (and hence accessible to planned future detectors), with the exception of a region when mu <0 where for m_{1/2}>~450 GeV, 4~< tanbeta~<20, the cross section drops to a minimum of about 1\times10^{-12} pb at m_{1/2}=600 GeV, tan beta=~10. In this region, the gluino and squarks lie above 1 TeV, but should still be accessible to the LHC.

hep-ph↗
arXiv2000

Dark Matter and Detector Cross Sections

We consider here the spin independent neutralino-proton cross section for a variety of SUGRA and D-brane models with R-parity invariance. The minimum cross section generally is >~ 1\times 10^{-(9-10)} pb (and hence accessible to future detectors) except for special regions of parameter space where it may drop to =~ 10^{-12} pb. In the latter case the gluino and squarks will be heavy (>~ 1 TeV).

hep-ph↗
arXiv2000

Maximum And Minimum Dark Matter Detection Cross Sections

The range of neutralino-proton cross sections for R-parity preserving supergravity models with GUT scale unification of the gauge coupling constants is examined. The models considered here are mSUGRA, models with non universal soft breaking and D-brane models. It is found that the current dark matter detectors are sampling significant parts of the SUSY parameter space and future detectors could sample almost the entire space. The special regions of parameter space that may be inaccessible to future detectors are seen to have a squark/gluino spectra beyond 1 TeV, but observable at the LHC.

hep-ph↗
arXiv2000

Yukawa Textures in Horava-Witten M-Theory

Recent advances in 11 dimensional Horava-Witten M-theory based on non-standard embeddings with torus fibered Calabi-Yau manifolds have allowed the construction of three generation models with Wilson line breaking to the Standard Model gauge symmetry. Central to these constructions is the existence of a set of 5-branes in the bulk. We examine within this framework the general structure of the matter Yukawa couplings and show that M-theory offers an alternate possible way of achieving the CKM and quark mass hierarchies without introducing undue fine tuning or (as in conventional analysis) small parameters raised to high powers. A phenomenological example is presented in accord with all CKM and quark mass data requiring mainly that the 5-branes cluster near the second orbifold plane, and that the instanton charges of the physical orbifold plane vanish. An explicit example of a three generation model with vanishing physical plane instanton charges based on a torus fibered Calabi-Yau three fold with a del Pezzo base $dP_7$ and Wilson line breaking is constructed.

hep-th↗
arXiv2000

Neutralino Proton Cross Sections For Dark Matter In SUGRA And D-BRANE Models

Neutralino proton cross sections are examined for models with R-parity invariance with universal soft breaking (mSUGRA) models, nonuniversal SUGRA models, and D-brane models. The region of parameter space where current dark matter detectors are sensitive, i.e. $1\times 10^{-6}$ pb, is examined. For mSUGRA models, detectors are sampling parts of the parametr space for tan$β>\sim 25$. The nonuniversal models can achieve cross sections that are a factor of 10-100 bigger or smaller then the universal one and in the former case sample regions tan$β>\sim 4$. The D-brane models considered require tan$β>\sim 15$. The inclusion of CP violating phases reduces the cross section by a factor of $\sim$ 2-3 (but also requires considerable fine tuning at the GUT scale). The expected particle spectra at accelerators are examined and seen to differ for each model. Three new regions of possible coannihilation are noted.

hep-ph↗
arXiv2000

CP Violaing Phases In SUSY GUT Models

Supersymmetric CP violating phases are examined within the framework of gravity mediated supergravity grand unified models with R parity invariance for models with a light ($\stackrel{<}{\sim} 1$ TeV) particle spectrum. In the minimal model, the nearness of the t quark Landau pole naturally suppresses the t-quark cubic soft breaking parameter at the electroweak scale allowing the electron and neutron experimental electric dipole moment (EDM) constraints to be satisfied with a large GUT scale phase. However, the EDM constraints require that $θ_B$, the quadratic soft breaking parameter phase be small at the electroweak scale unless tan$β\stackrel{<}{\sim}3$, which then implies that at the GUT scale this phase must be large and highly fine tuned to satisfy radiative breaking of $SU(2)\times U(1)$. Similar results hold for non minimal models, and a possible GUT model is discussed where all GUT scale CP violating phases are naturally small (i.e. O($10^{-2})$). An interesting D-brane model is examined which enhances the size of the phases over much of the parameter space at the electroweak sector for tan$β\stackrel{<}{\sim} 5$, but still possesses the fine tuning problem at the GUT scale.

hep-ph↗
arXiv2000

Neutralino Proton Cross Sections In Supergravity Models

The neutralino-proton cross section is examined for supergravity models with R-parity invariance with universal and non-universal soft breaking. The region of parameter space that dark matter detectors are currently (or will be shortly) sensitive i.e. $(0.1-10)\times 10^{-6}$ pb, is examined. For universal soft breaking (mSUGRA), detectors with sensitivity $σ_{\tildeχ_{1}^{0}-p} \geq 1 \times 10^{-6}$ pb will be able to sample parts of the parameter space for $\tan β\stackrel{>}{\sim} 25$. Current relic density bounds restrict $m_{\tildeχ_{1}^{0}} \leq 120$ GeV for the maximum cross sections, which is below where astronomical uncertainties about the Milky Way are relevant. Nonuniversal soft breaking models can allow much larger cross sections and can sample the parameter space for $\tan β\stackrel{>}{\sim} 4$. In such models, $m_0$ can be quite large reducing the tension between proton decay bounds and dark matter analysis. We note the existance of two new domains where coannihilation effects can enter, i.e. for mSUGRA at large $\tan β$, and for nonuniversal models with small $\tan β$.

hep-ph↗
arXiv1999

CP Violating Phases, Nonuniversal Soft Breaking And D-brane Models

The question of CP violating phases and electric dipole moments (EDMs)for the electron ($d_e$) and the neutron ($d_n$) for supergravity models with nonuniversal soft breaking is considered for models with a light ($\stackrel{<}{\sim}$1 TeV) mass spectrum and R-parity invariance. As with models with universal soft breaking (mSUGRA) one finds a serious fine tuning problem generally arises for $θ_{0B}$ (the phase of the B soft breaking parameter at the GUT scale), if the experimental EDM constraints are obeyed and radiative breaking of $SU(2)_L\times U(1)_Y$ occurs. A D-brane model where $SU(3)_C\times U(1)_Y$ is associated with one set of 5-branes and $SU(2)_L$ with another intersecting set of 5-branes is examined, and the cancellation phenomena is studied over the parameter space of the model. Large values of $θ_B$ (the phase of B at the electroweak scale) can be accommodated, though again $θ_{0B}$ must be fine tuned. Using the conventional prescription for calculating $d_n$, one finds the region in parameter space where the experimental EDM constraints on both $d_e$ and $d_n$ hold is significantly reduced, and generally requires tan$β\stackrel{<}{\sim}$5 for most of the parameter space, though there are small allowed regions even for tan$β\stackrel{>}{\sim}$10. We find the Weinberg three gluon term generally makes significant contributions, and results are sensitive to the values of quark masses.

hep-ph↗
arXiv1999

The Tevatron Tripler: How to Upgrade the Fermilab Tevatron for the Higgs Boson and Supersymmetry

Recent advances in superconductor properties and superconducting magnet technology have made it possible to build cost-effective, high-performance dipoles with a field of 12 Tesla - 3 times the field strength of the Tevatron. Such magnets could be used to upgrade Fermilab's collider in its existing tunnel to a collision energy $\sqrt s$= 6 TeV and luminosity {$\cal L$}$>$ 10$^{33}$ cm$^{-2}$s$^{-1}$. We have calculated the parton luminosities for quark-antiquark and gluon-gluon scattering for the Tevatron, the Tripler, and LHC. In most models of the Higgs field and supersymmetry, the Tripler would have a high likelihood to discover many of the predicted particle states.

hep-ex↗
arXiv1999

Grand Unification Scale CP Violating Phases And The Electric Dipole Moment

The question of CP violating phases in supersymmetry and electric dipole moments (EDMs) is considered within the framework of supergravity grand unification (GUT) models with a light ($\stackrel{<}{\sim}$1 TeV) mass spectrum. In the minimal model, the nearness of the t-quark Landau pole automatically suppresses the t-quark cubic soft breaking phase at the electroweak scale. However, current EDM data require the quadratic soft breaking phase to be small at the electroweak scale unless tan$β$ is small (tan$β\stackrel{<}{\sim}$3), and the EDM data combined with the requirement of electroweak symmetry breaking require this phase to be both large and highly fine tuned at the GUT scale unless tan$β$ is small. Non minimal models are also examined, and generally show the same behavior.

hep-ph↗
arXiv1999

Annual Modulation Signature for the Direct Detection of Milky Way Wimps and Supergravity Models

An analysis is given of the annual modulation signal for the direct detection of relic neutralinos within the framework of supergravity unified models. It is shown that both the minimal and the non-minimal SUGRA models can generate neutralino-proton cross-sections at the level compatible with the signals reported in the DAMA experiment at the Gran Sasso National Laboratory. Effects of proton stability on the analysis of the DAMA data in the minimal and the non-minimal SUGRA models are also discussed.

hep-ph↗
arXiv1998

Trilepton Signal of Grand Unified Models at the Tevatron

At the Tevatron, the most promising channel to detect supersymmetry is three leptons plus missing energy, where the leptons are $e$'s and/or $μ$'s. This final state appears from the production of chargino and second lighetst neutralino. However in grand unified models with universal scalar masses at the grand unified scale, this final state mostly consists of $τ$'s which are hard to detect. We show that for some regions of non universality in the scalar masses at the GUT scale based on unifying groups like SU(5) or SO(10), the final state mostly consists of 3$l$+${\rlap/E}_T$ and $τll$+${\rlap/E}_T$. The first mode has very high detection efficiency and the second one is expected to have high detection efficency as well. We also show that these models can have enough events in these modes to be detected in RUN II.

hep-ph↗
arXiv1998

Grand Unification and B & L Conservation

A review of baryon and lepton conservation in supersymmetric grand unified theories is given. Proton stability is discussed in the minimal SU(5) supergravity grand unification and in several non-minimal extensions such as the $SU(3)^3$, SO(10) and some string based models. Effects of dark matter on proton stability are also discussed and it is shown that the combined constraints of dark matter and proton stability constrain the sparticle spectrum. It is also shown that proton lifetime limits put severe constraints on the event rates in dark matter detectors. Future prospects for the observation of baryon and lepton number violation are also discussed.

hep-ph↗
arXiv1998

Accurate Cosmological Parmeters and Supersymmetric Particle Properties

Future sattelite, balloon and ground based experiments will give precision determinations of the basic cosmological parameters and hence determine the amount of cold dark matter accurately. We consider here two cosmological models, the nuCDM model and the LambdaCDM model, and examine within the framework of supergravity grand unification the effect this will have for these models on supersymmetry searches at accelerators. In the former example the gluino (neutralino) mass has an upper bound of about 720(100) GeV and gaps (forbidden regions) may deveop at lower energies. In the latter case the upper bound occurs at gluino (neutralino) mass of about 520(70) GeV with squarks and selectron becoming light when gluino (neutralino) masses are greater than 420(55) GeV. Both models are sensitive to non-universal soft breaking masses, and show a correlation between large (small) dark matter detector rates and low (high) b -> s+ gamma branching ratio.

hep-ph↗
arXiv1998

Implications of Planck and MAP Measurements On Sparticle Spectra

Future sattelite (MAP and Planck) balloon and ground based experiments will the determine the basic cosmological parameters within a few percent. We examine here the effect of this on constraining the SUSY parameter space for supergravity R-parity conserving models (with tanbeta < 25) for the cases of nuCDM and LambdaCDM cosmological models. For the nuCDM (LambdaCDM) models, the gluino mass is restricted by m_g~ < 720(540)GeV. In both cases, the cosmological constraints are sensitive to non-universal SUSY soft breaking producing a lower bound m_g~ > 400GeV in some regions and for the nuCDM model, gaps in the allowed m_g~ range for other regions. For gluino (neutralino) masses greater than 450(65)GeV, m_0 is constrained to be small making the quark and slepton mass light generally light and detrmined mostly by m_g~.

hep-ph↗
arXiv1998

Non-universal Soft SUSY Breaking and Dark Matter

A brief review of non-universalities in the soft SUSY breaking sector of supergravity grand unification is given. The effects of these non-universalities on the analysis of event rates in neutralino nucleus scattering are discussed. An analysis is also given of the implications of the simultaneous imposition of proton stability and dark matter constraints. One finds that these constraints put an upper limit on the gluino mass.

hep-ph↗
arXiv1998

Limits on SUSY particle Spectra from Proton Stability and Dark Matter Constraints

It is shown that the combined constraints on the amount of cold dark matter and of proton stability produce a stringent upper limit on the gluino mass $m_{\tilde g}$ (and hence on the lightest neutralino mass $m_{χ_1^0}\simeq m_{\tilde g}/7$) for a large class of gravity mediated supergravity unified models. One finds that for the minimal SU(5) model current data (Kamiokande) restricts $m_{\tilde g}\leq 400$ GeV for a scalar soft breaking mass $m_0\leq 1$ TeV. Expected future data from Super Kamionkande and ICARUS will be sensitive to the entire range of gluino mass for $m_0\leq 1$ TeV, and be able to exclude the region $m_{\tilde g}\geq 500$ GeV for $m_0\leq 5$ TeV. Effects of quark mass textures are studied and one finds that the bound $m_{\tilde g}\leq 500$ GeV holds when the experimental proton lifetime for the $p\to \bar νK^+$ mode becomes $\geq 5\times 10^{32}$ yr.Implications of these results for a test of these models at the Tevatron and at the LHC are discussed. The effects of non-universal soft breaking in the Higgs and the third generation squark sectors are also examined, and it is found that the proton lifetime is sensitive to these non-universal effects. The current data already eliminates some regions of non-universalities. The constraints of proton stability on the direct detection of dark matter are seen to reduce the maximum event rates by as much as a factor of $10^3$.

hep-ph↗