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Full-Text Articles in Physics
Effects Of Large Cp Phases On The Proton Lifetime In Supersymmetric Unification, Tarek Ibrahim, Pran Nath
Effects Of Large Cp Phases On The Proton Lifetime In Supersymmetric Unification, Tarek Ibrahim, Pran Nath
Pran Nath
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 …
Cp Violation Effects On $B^0_{S,D}\To \It L^+\It L^-$ In Supersymmetry At Large $\Tan\Beta$, Tarek Ibrahim, Pran Nath
Cp Violation Effects On $B^0_{S,D}\To \It L^+\It L^-$ In Supersymmetry At Large $\Tan\Beta$, Tarek Ibrahim, Pran Nath
Pran Nath
An analytic analysis of the CP violating effects arising from the soft SUSY breaking parameters on the decays $B^0_{s,d}\to \it l^+\it l^-$ at large $\tan\beta$ is given. It is found that the phases have a strong effect on the branching ratio and in some regions of the parameter space they can lead to a variation of the branching ratio by as much as 1-2 orders of magnitude. These results have important implications for the discovery of the $B^0_{s}\to \mu^+\mu^-$ signal in RUNII of the Tevatron and further on how the parameter space of SUSY models will be limited once the …
Effects Of Extra Space-Time Dimensions On The Fermi Constant, Pran Nath, Masahiro Yamaguchi
Effects Of Extra Space-Time Dimensions On The Fermi Constant, Pran Nath, Masahiro Yamaguchi
Pran Nath
Effects of Kaluza-Klein excitations associated with extra dimensions with large radius compactifications on the Fermi constant are explored. It is shown that the current precision determinations of the Fermi constant, of the fine structure constant, and of the W and Z mass put stringent constraints on the compactification radius. The analysis excludes one extra space time dimension below $\sim 1.6$ TeV, and excludes 2, 3 and 4 extra space dimensions opening simultaneously below $\sim$ 3.5 TeV, 5.7 TeV and 7.8 TeV at the $90% CL$. Implications of these results for future collider experiments are discussed.
Effects Of Kaluza-Klein Excitations On G_Μ-2, Pran Nath, Masahiro Yamaguchi
Effects Of Kaluza-Klein Excitations On G_Μ-2, Pran Nath, Masahiro Yamaguchi
Pran Nath
An analysis of the effects associated with the Kaluza-Klein excitations of the photon and of the W and Z bosons on g_{\mu}-2 for d number of extra dimensions with large radius compactifications is given. The Kaluza-Klein effects on g_{\mu}-2 are found to be very sensitive to the number of extra dimensions. For models where the quark-lepton generations live on the 4D wall, it is shown that when the constraints from the Kaluza-Klein corrections to the Fermi constant are included, the effects of the Kaluza-Klein excitations to g_{\mu}-2 become too small to be observable. A model which evades Kaluza-Klein corrections to …
Effects Of Cp Violation On Event Rates In The Direct Detection Of Dark Matter, Utpal Chattopadhyay, Tarek Ibrahim, Pran Nath
Effects Of Cp Violation On Event Rates In The Direct Detection Of Dark Matter, Utpal Chattopadhyay, Tarek Ibrahim, Pran Nath
Pran Nath
A full analytic analysis of the effects of CP violating phases on the event rates in the direct detection of dark matter in the scattering of neutralinos from nuclear targets is given. The analysis includes CP violating phases in softly broken supersymmetry in the framework of the minimal supersymmetric standard model (MSSM) when generational mixings are ignored. A numerical analysis shows that large CP violating phases including the constraints from the experimental limits on the neutron and the electron electric dipole moment (EDM) can produce substantial effects on the event rates in dark matter detectors.
Effects Of Large Cp Violating Phases On $G_{\M}-2$ In The Mssm, Tarek Ibrahim, Pran Nath
Effects Of Large Cp Violating Phases On $G_{\M}-2$ In The Mssm, Tarek Ibrahim, Pran Nath
Pran Nath
Effects of CP violation on the supersymmetric electro-weak correction to the anomalous magnetic moment of the muon are investigated with the most general allowed set of CP violating phases in MSSM. The analysis includes contributions from the chargino and the neutralino exchanges to the muon anomaly. The supersymmetric contributions depend only on specific combinations of CP phases. The independent set of such phases is classified. We analyse the effects of the phases under the EDM constraints and show that large CP violating phases can drastically affect the magnitude of the supersymmetric electro-weak contribution to $a_{\mu}$ and may even affect its …
Effective Lagrangian For $\Bar Q\Tilde Q'_I\Chi^+_J$, $\Bar Q\Tilde Q'_I\Chi^0_J$ Interactions And Fermionic Decays Of The Squarks With Cp Phases, Tarek Ibrahim, Pran Nath
Effective Lagrangian For $\Bar Q\Tilde Q'_I\Chi^+_J$, $\Bar Q\Tilde Q'_I\Chi^0_J$ Interactions And Fermionic Decays Of The Squarks With Cp Phases, Tarek Ibrahim, Pran Nath
Pran Nath
The one loop corrected effective Lagrangian for the quark-squark-chargino and quark-squark-neutralino interactions is computed. The effective Lagrangian takes into account the loop corrections arising from the exchange of the gluinos, charginos, neutralinos, W, Z, the charged Higgs, and the neutral Higgs. We further analyze the squark decays into charginos and neutralinos and discuss the effect of the loop corrections on them. The analysis takes into account CP phases in the soft parameters. It is found that the loop corrections to the stop decay widths into chargino and neutralinos can be as much as thirty percent or even larger. Further, the …
Effects Of Gravitational Smearing On Predictions Of Supergravity Grand Unification, T. Dasgupta, P. Mamales, Pran Nath
Effects Of Gravitational Smearing On Predictions Of Supergravity Grand Unification, T. Dasgupta, P. Mamales, Pran Nath
Pran Nath
Limits on gravitational smearing from the dominant dimension 5 operator (with strength characterised by $cM/2M_{Planck}$) are obtained using the LEP data in supersymmetric SU(5) grand unification. Effects of c on the quasi infrared fixed point solutio ns of $m_b/m_{\tau}$ unification are also analysed. It is found that $c>0$ softens and $c<0$ stiffens the fixed point constraint. The effect of c on the upper bound of the Higgs triplet mass is analysed and the existence of a scaling induced by c is discussed. Tests for the existence of gravitational smearing are discussed.
Effective Lagrangian For The $\Chi^+_I\Chi_J^0h^-$ Interaction In The Minimal Supersymmetric Standard Model And Charged Higgs Decays, Tarek Ibrahim, Pran Nath, Anastasios Psinas
Effective Lagrangian For The $\Chi^+_I\Chi_J^0h^-$ Interaction In The Minimal Supersymmetric Standard Model And Charged Higgs Decays, Tarek Ibrahim, Pran Nath, Anastasios Psinas
Pran Nath
We extend previous analyses of the supersymmetric loop correction to the charged Higgs couplings to include the coupling $H^{\pm}\chi^{\mp}\chi^0$. The analysis completes the previous analyses where similar corrections were computed for $H^+\bar t b$ ($H^-t\bar b$), and for $H^+\tau^- \bar\nu_{\tau}$ ($H^- \tau^+ \nu_{\tau}$) couplings within the minimal supersymmetric standard model. The effective one loop Lagrangian is then applied to the computation of the charged Higgs decays. The sizes of the supersymmetric loop correction on branching ratios of the charged Higgs $H^+(H^-)$ into the decay modes $t\bar b$ ($\bar t b$), $\bar\tau\nu_{\tau}$ ($\tau \bar \nu_{\tau}$), and $\chi_i^+\chi_j^0(\chi_i^-\chi_j^0)$ (i=1,2; j=1-4) are investigated …
Cp Violation From Standard Model To Strings, Tarek Ibrahim, Pran Nath
Cp Violation From Standard Model To Strings, Tarek Ibrahim, Pran Nath
Pran Nath
A review of CP violation from the Standard Model to strings is given which includes a broad landscape of particle physics models, encompassing the non-supersymmetric 4D extensions of the standard model, and models based on supersymmetry, on extra dimensions, on strings and on branes. The supersymmetric models discussed include complex mSUGRA and its extensions, while the models based on extra dimensions include 5D models including models based on warped geometry. CP violation beyond the standard model is central to achieving the desired amount of baryon asymmetry in the universe via baryogenesis and leptogenesis. They also affect a variety of particle …
Detecting Physics At The Post-Gut And String Scales By Linear Colliders, R. Arnowitt, Pran Nath
Detecting Physics At The Post-Gut And String Scales By Linear Colliders, R. Arnowitt, Pran Nath
Pran Nath
The ability of linear colliders to test physics at the post-GUT scale is investigated. Using current estimates of measurements available at such accelerators, it is seen that soft breaking masses can be measured with errors of about (1-20)%. Three classes of models in the post-GUT region are examined: models with universal soft breaking masses at the string scale, models with horizontal symmetry, and string models with Calabi-Yau compactifications. In each case, linear colliders would be able to test directly theoretical assumptions made at energies beyond the GUT scale to a good accuracy, distinguish between different models, and measure parameters that …
Aspects Of The Stueckelberg Extension, Boris Körs, Pran Nath
Aspects Of The Stueckelberg Extension, Boris Körs, Pran Nath
Pran Nath
A detailed analysis of a Stueckelberg extension of the electro-weak gauge group with an extra abelian U(1)ₓ factor is presented for the Standard Model as well as for the MSSM. The extra gauge boson gets massive through a Stueckelberg type coupling to a pseudo-scalar, instead of a Higgs effect. This new massive neutral gauge boson Z′ has vector and axial vector couplings uniquely different from those of conventional extra abelian gauge bosons, such as appear e.g. in GUT models. The extended MSSM furthermore contains two extra neutralinos and one extra neutral CP-even scalar, the latter with a mass larger than …
Cp Violation And The Muon Anomaly In N=1 Supergravity, Tarek Ibrahim, Pran Nath
Cp Violation And The Muon Anomaly In N=1 Supergravity, Tarek Ibrahim, Pran Nath
Pran Nath
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 gμ−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 gμ−2, and that the numerical size of such a correction can be as large or larger …
Constraints On The Minimal Supergravity Model From The B→Sγ Decay, Jizhi Wu, Richard Arnowitt, Pran Nath
Constraints On The Minimal Supergravity Model From The B→Sγ Decay, Jizhi Wu, Richard Arnowitt, Pran Nath
Pran Nath
The constraints on the minimal supergravity model from the b → sγ decay are studied. A large domain in the parameter space for the model satisfies the CLEO bound, BR(b → sγ) < 5.4 × 10−4. However, the allowed domain is expected to diminish significantly with an improved bound on this decay. The dependence of the b → sγ branching ratio on various parameters is studied in detail. It is found that, for At < 0 and the top quark mass within the vicinity of the center of the CDF value, mtpole = 174±17 GeV, there exists only a small allowed domain because the light stop is tachyonic for most of the parameter space. A similar phenomenon exists for a lighter top and At negative when the GUT coupling constant is slightly reduced. For At > 0, however, the branching ratio is much less sensitive to small changes in mt, and αG.)
Cp Violation In Susy, Strings And Branes, Tarek Ibrahim, Pran Nath
Cp Violation In Susy, Strings And Branes, Tarek Ibrahim, Pran Nath
Pran Nath
A review is given of CP violation in a broad class of models based on supersymmetry, superstrings and brane models. Such models contain typically large CP violating phases which affect a variety of supersymmetric phenomenon at low energies and affect search for supersymmetry at colliders and in dark matter experiments. We focus here on few such phenomena, specifically the mixing of the CP even and the CP odd Higgs bosons which can be induced by loop corrections and on CP violation in the muon sector. Possible signals for the observation of CP violation are also discussed.
Cosmological Constraints And Su(5) Supergravity Grand Unification, R. Arnowitt, Pran Nath
Cosmological Constraints And Su(5) Supergravity Grand Unification, R. Arnowitt, Pran Nath
Pran Nath
The predictions of SU(5) supergravity models with radiative breaking constrained by experimental proton decay bounds are discussed. It is shown that cosmological constraints further restrict the parameter space but can be satisfied for a wide range of parameters. It is also shown that no serious fine tuning problems (either at MSUSY or MGUT) exist.
Annual Modulation Signature For The Direct Detection Of Milky Way Wimps And Supergravity Models, R. Arnowitt, Pran Nath
Annual Modulation Signature For The Direct Detection Of Milky Way Wimps And Supergravity Models, R. Arnowitt, Pran Nath
Pran Nath
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 neutralinoproton 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.
B−Τ Unification, Gμ−2, The B→S+Γ Constraint, And Nonuniversalities, Utpal Chattopadhyay, Pran Nath
B−Τ Unification, Gμ−2, The B→S+Γ Constraint, And Nonuniversalities, Utpal Chattopadhyay, Pran Nath
Pran Nath
An analysis is given of the b−τ Yukawa coupling unification in view of the recent result from Brookhaven on gμ−2 and under the constraint of b→s+γ. We explore b−τ unification under the above constraints for nonuniversal boundary conditions for the soft SUSY breaking parameters. We find new regions of the parameter space where significant negative supersymmetric contribution to the b quark mass can arise and b−τ unification within SU(5) framework can occur with nonuniversal gaugino masses. Specifically we find that for the case where the gaugino mass matrix transforms like a 24 plet one finds a negative contribution to the …
Baryon Instability In Susy Models, Pran Nath, R. Arnowitt
Baryon Instability In Susy Models, Pran Nath, R. Arnowitt
Pran Nath
A review is given of nucleon instability in SUSY models. The minimal SU(5) model is discussed in detail.
Connecting The Direct Detection Of Dark Matter With Observation Of Sparticles At The Lhc, Daniel Feldman, Zuowei Liu, Pran Nath
Connecting The Direct Detection Of Dark Matter With Observation Of Sparticles At The Lhc, Daniel Feldman, Zuowei Liu, Pran Nath
Pran Nath
An analysis is given connecting event rates for the direct detection of neutralino dark matter with the possible signatures of supersymmetry at the LHC. It is shown that if an effect is seen in the direct detection experiments at a level of O(10⁻⁴⁴) cm² for the neutralino-proton cross section, then within the mSUGRA model the next heavier particle above the neutralino is either a stau, a chargino, or a CP odd/CP even (A/H) Higgs boson. Further, the collider analysis shows that models with a neutralino-proton cross section at the level of (1 − 5) × 10⁻⁴⁴ cm² could be probed …
Corrections To The Higgs Boson Masses And Mixings From Chargino, W, And Charged Higgs Exchange Loops And Large Cp Phases, Tarek Ibrahim, Pran Nath
Corrections To The Higgs Boson Masses And Mixings From Chargino, W, And Charged Higgs Exchange Loops And Large Cp Phases, Tarek Ibrahim, Pran Nath
Pran Nath
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. …