Effects of SO(10) D-Terms on SUSY Signals at the Tevatron

We study signals for the production of superparticles at the Tevatron in supergravity scenarios based on the Grand Unified group SO(10). The breaking of this group introduces extra contributions to the masses of all scalars, described by a single new parameter. We find that varying this parameter can considerably change the size of various expected signals studied in the literature, with different numbers of jets and/or charged leptons in the final state. The ratios of these signal can thus serve as a diagnostic to detect or constrain deviations from the much--studied scenario where all scalar masses are universal at the GUT scale. Moreover, under favorable circumstances some of these signals, and/or new signals involving hard $b-$jets, should be observable at the next run of the Tevatron collider even if the average scalar mass lies well above the gluino mass.Comment: 17 pages, LaTeX including 3 postscript figures, uses equation.st

Non-zero trilinear parameter in the mSUGRA model - dark matter and collider signals at Tevatron and LHC

Phenomenologically viable and interesting regions of parameter space in the minimal super-gravity (mSUGRA) model with small $m_0$ and small $m_{1/2}$ consistent with the WMAP data on dark matter relic density and the bound on the mass of the lightest Higgs scalar $m_h>$ 114 GeV from LEP2 open up if the rather adhoc assumption $A_0$=0, where $A_0$ is the common trilinear soft breaking parameter, employed in most of the existing analyses is relaxed. Since this region corresponds to relatively light squarks and gluinos which are likely to be probed extensively in the very early stages of the LHC experiments, the consequences of moderate or large negative values of $A_0$ are examined in detail. We find that in this region several processes including lightest supersymmetric particle (LSP) pair annihilation, LSP - lighter tau slepton (${\tilde \tau}_1$) coannihilation and LSP - lighter top squark (${\tilde t}_1$) coannihilation contribute to the observed dark matter relic density. %\sout{The possibility that a relic density producing ${\tilde t}_1$ can be %observed at the current experiments at the Tevatron is wide open.} The possibility that a ${\tilde t}_1$ that can participate in coannihilation with the lightest neutralino to satisfy the WMAP bound on relic density and at the same time be observed at the current experiments at the Tevatron is wide open. At the LHC a large number of squark - gluino events lead to a very distinctive semi-inclusive signature $\tau^\pm$+X$_\tau$ (anything without a tau lepton) with a characteristic size much larger than $e^\pm$+X$_e$ or $\mu^\pm$+X$_\mu$ events.Comment: Some minor changes made in the text. To appear in Phys Rev

LHC Signature of the Minimal SUGRA Model with a Large Soft Scalar Mass

Thanks to the focus point phenomenon, it is quite {\it natural} for the minimal SUGRA model to have a large soft scalar mass m_0 > 1 TeV. A distinctive feature of this model is an inverted hierarchy, where the lighter stop has a significantly smaller mass than the other squarks and sleptons. Consequently, the gluino is predicted to decay dominantly via stop exchange into a channel containing 2b and 2W along with the LSP. We exploit this feature to construct a robust signature for this model at the LHC in leptonic channels with 3-4 b-tags and a large missing-E_T.Comment: Small clarifications added. Final version to appear in Phys. Lett.

Neutrino parameters from matter effects in PeeP_{ee} at long baselines

We show that the earth matter effects in the ${\rm {\nu_e \to \nu_e}}$ survival probability can be used to cleanly determine the third leptonic mixing angle $\theta_{13}$ and the sign of the atmospheric neutrino mass squared difference, $\Delta m^2_{31}$, using a $\beta$-beam as a $\nu_e$ source.Comment: 4 pages, 4 eps figures; comments and references added, to appear in Phys. Rev.

Top squark and neutralino decays in a R-parity violating model constrained by neutrino oscillation data

In a R-parity violating (RPV) model of neutrino mass with three bilinear couplings $\mu_i$ and three trilinear couplings $\lambda'_{i33}$, where $i$ is the lepton index, we find six generic scenarios each with a distinctive pattern of the trilinear couplings consistent with the oscillation data. These patterns may be reflected in direct RPV decays of the lighter top squark or in the RPV decays of the lightest superparticle, assumed to be the lightest neutralino. Typical signal sizes at the Tevatron RUN II and the LHC have been estimated and the results turn out to be encouraging.Comment: 20 pages, 4 figures, LaTex,typos corrected and reference added for section 2, a paragraph has been added in the conclusion par

Oscillation Effects On Neutrinos From The Early Phase Of a Nearby Supernova

Neutrinos emitted during stellar core collapse leading to a supernova are primarily of the electron neutrino type at source which may undergo oscillation between flavor eigenstates during propagation to an earth-bound detector. Although the number of neutrinos emitted during the pre-bounce collapse phase is much smaller than that emitted in the post-bounce phase (in which all flavors of neutrinos are emitted), a nearby supernova event may nevertheless register a substantial number of detections from the pre-bounce phase at SuperKamiokande (SK) and the Sudbury Neutrino Observatory (SNO). The calorimetric measurement of the supernova neutrino fluence from this stage via the charge current and neutral current detection channels in SNO and the corresponding distortion of detected spectrum in SK over the no-oscillation spectrum, can probe information about neutrino mass difference and mixing which are illustrated here in terms of two- and three-flavor oscillation models

Interplay between Oxo and Fluoro in Vanadium Oxyfluorides for Centrosymmetric and Non-Centrosymmetric Structure Formation

Herein, we report the syntheses of two lithium-vanadium oxide-fluoride compounds crystallized from the same reaction mixture through a time variation experiment. A low temperature hydrothermal route employing a viscous paste of V2O5, oxalic acid, LiF, and HF allowed the crystallization of one metastable phase initially, Li2VO0.55 (H2O)0.45F5·2H2O (I), which on prolonged heating transforms to a chemically similar yet structurally different phase, Li3VOF5 (II). Compound I crystallizes in centrosymmetric space group, I2/a with a = 6.052(3), b = 7.928(4), c = 12.461(6) Å, and β = 103.99(2)⁰ , while compound II crystallizes in a non-centrosymmetric (NCS) space group, Pna21 with a = 5.1173(2), b = 8.612(3), c = 9.346(3) Å. Synthesis of NCS crystals are highly sought after in solid-state chemistry for their second-harmonic-generation (SHG) response and compound II exhibits SHG activity albeit non-phase-matchable. In this article, we also describe their magnetic properties which helped in unambiguous assignment of mixed valency of V (+4/+5) for Li2VO0.55 (H2O)0.45F5·2H2O (I) and +4 valency of V for Li3VOF5 (II)