Lepton Flavor Violation within a realistic SO(10)/G(224) Framework

Lepton flavor violation (LFV) is studied within a realistic unified framework, based on supersymmetric SO(10) or an effective G(224) = SU(2)_L\times SU(2)_R\times SU(4)^c symmetry, that successfully describes (i) fermion masses and mixings, (ii) neutrino oscillations, as well as (iii) CP violation. LFV emerges as an important prediction of this framework, bringing no new parameters, barring the few SUSY parameters, which are assumed to be flavor-universal at M^*>= M_{GUT}. We study LFV (i.e. \mu -> e\gamma, \tau -> \mu\gamma, \tau -> e\gamma and \mu N -> e N) within this framework by including contributions both from the presence of the right handed neutrinos as well as those arising from renormalization group running in the post-GUT regime (M^* to M_{GUT}). Typically the latter, though commonly omitted in the literature, is found to dominate. Our predicted rates for \mu -> e\gamma show that while some choices of (m_o, m_{1/2}) are clearly excluded by the current empirical limit, this decay should be seen with an improvement of the current sensitivity by a factor of 10--100, even if sleptons are moderately heavy (<= 800 GeV, say). For the same reason, \mu-e conversion (\mu N -> e N) should show in the planned MECO experiment. Implications of WMAP and (g-2)_{\mu}-measurements are noted, as also the significance of the measurement of parity-odd asymmetry in the decay of polarized \mu^+ into e^+ \gamma.Comment: 17 pages, 1 figur

Anomalous U(1) symmetry and lepton flavor violation

We show that in a large class of models based on anomalous U(1) symmetry which addresses the fermion mass hierarchy problem, leptonic flavor changing processes are induced that are in the experimentally interesting range. The flavor violation occurs through the renormalization group evolution of the soft SUSY breaking parameters between the string scale and the U(1)_A breaking scale. We derive general expressions for the evolution of these parameters in the presence of higher dimensional operators. Several sources for the flavor violation are identified: flavor-dependent contributions to the soft masses from the U(1)_A gaugino, scalar mass corrections proportional to the trace of U(1)_A charge, non-proportional A-terms from vertex corrections, and the U(1)_A D-term. Quantitative estimates for the decays \mu -> e \gamma and \tau -> \mu \gamma are presented in supergravity models which accommodate the relic abundance of neutralino dark matter.Comment: References added, typos corrected, 28 pages LaTeX, includes 14 eps figure

The performance of organ dysfunction scores for the early prediction and management of severity in acute pancreatitis: an exploratory phase diagnostic study

Objective: To evaluate contemporary organ dysfunction scoring systems for early prediction of severity in acute pancreatitis (AP). Methods: In a consecutive cohort of 181 patients with AP, organ dysfunction scores (logistic organ dysfunction system [LODS] score, Marshall organ dysfunction score, and sequential organ failure assessment score) were collected at 24 and 48 hours. Acute Physiology and Chronic Health Evaluation II (APACHE II) scores were calculated on admission and 24 and 48 hours and C-reactive protein level measured at 48 hours. Patients who died or used critical care facilities (level 2/3) during admission were classed as severe. Results: Area under curve for APACHE II score at admission was 0.78 (95% confidence interval, 0.69-0.86). At 24 hours, area under curve for LODS, Marshall organ dysfunction system, sequential organ failure assessment, and APACHE II scores were 0.82, 0.80, 0.80, and 0.82, respectively. The LODS score at cutoff of 1 achieved 90% sensitivity and 69% specificity, corresponding to a positive predictive value of 38%. Acute Physiology and Chronic Health Evaluation II score as a rule-out for selection of mild cases at a test threshold of 9 (scores <= 8 being selected) gives homogeneity of 91% and efficiency of 79%. Conclusions: Contemporary organ dysfunction scoring systems provides an objective guide to stratification of management, but there is no perfect score. All scores evaluated here perform equivalently at 24 hours. Acute Physiology and Chronic Health Evaluation II may have practical clinical value as a rule-out test

Lepton Flavor Violation and the Origin of the Seesaw Mechanism

The right--handed neutrino mass matrix that is central to the understanding of small neutrino masses via the seesaw mechanism can arise either (i) from renormalizable operators or (ii) from nonrenormalizable or super-renormalizable operators, depending on the symmetries and the Higgs content of the theory beyond the Standard Model. In this paper, we study lepton flavor violating (LFV) effects in the first class of seesaw models wherein the \nu_R Majorana masses arise from renormalizable Yukawa couplings involving a B-L = 2 Higgs field. We present detailed predictions for \tau -> \mu + \gamma and \mu -> e + \gamma branching ratios in these models taking the current neutrino oscillation data into account. Focusing on minimal supergravity models, we find that for a large range of MSSM parameters suggested by the relic abundance of neutralino dark matter and that is consistent with Higgs boson mass and other constraints, these radiative decays are in the range accessible to planned experiments. We compare these predictions with lepton flavor violation in the second class of models arising entirely from the Dirac Yukawa couplings. We study the dependence of the ratio r \equiv B(\mu -> e+\gamma)/B(\tau ->\mu +\gamma) on the MSSM parameters and show that measurement of r can provide crucial insight into the origin of the seesaw mechanism.Comment: 20 pages, Revtex, 7 figure

SUSY GUT Models of Neutrino Mass and mu to e gamma

It is explained why excessive mu to e gamma can be a problem in SUSY GUT see-saw models of neutrino mass, and ways that this problem might be avoided are discussed.Comment: 13 pages, LaTeX, references adde

Seesaw and Lepton Flavour Violation in SUSY SO(10)

That $\mu \to e, \gamma$ and $\tau \to \mu,\gamma$ are sensitive probes of SUSY models with a see-saw mechanism is a well accepted fact. Here we propose a `top-down' approach in a general SUSY SO(10) scheme. In this framework, we show that at least one of the neutrino Yukawa couplings is as large as the top Yukawa coupling. This leads to a strong enhancement of these leptonic flavour changing decay rates. We examine two `extreme' cases, where the lepton mixing angles in the neutrino Yukawa couplings are either small (CKM-like) or large (PMNS-like). In these two cases, we quantify the sensitivity of leptonic radiative decays to the SUSY mass spectrum. In the PMNS case, we find that the ongoing experiments at the B-factories can completely probe the spectrum up to gaugino masses of 500 GeV (any tan $\beta$). Even in the case of CKM-like mixings, large regions of the parameter space will be probed in the near future, making these two processes leading candidates for indirect SUSY searches.Comment: 22 pages with 2 figures. Figures for \tau -> \mu \gamma decay corrected after typo found in the program. Decay \mu -> e gamma completely unchanged and conclusions basicaly unchange

Pure Leptonic Gauge Symmetry, Neutrino Masses and Dark Matter

A possible extension of the Standard Model to include lepton number as local gauge symmetry is investigated. In such a model, anomalies are canceled by two extra fermions doublet. After leptonic gauge symmetry spontaneously broken, three active neutrinos may acquire non-zero Majorana masses through the modified Type-II seesaw mechanism. Constraints on the model from electro-weak precision measurements are studied. Due to the $Z_2$ discrete flavor symmetry, right-handed Majorana neutrinos can serve as cold dark matter candidate of the Universe. Constraint from dark matter relic abundance is calculated.Comment: 13 pages, 2 figures; typos corrected, comments and references added, to appear in Phys. Lett.

Exclusive Semileptonic Rare Decays B→K(∗)l+l−B \to K^{(*)} l^+ l^- in a SUSY SO(10) GUT

In the SUSY SO(10) GUT context, we study the exclusive processes $B \to K^{(*)} l^+l^-(l=\mu,\tau)$. Using the Wilson coefficients of relevant operators including the new operators $Q_{1,2}^{(\prime)}$ which are induced by neutral Higgs boson (NHB) penguins, we evaluate some possible observables associated with these processes like, the invariant mass spectrum (IMS), lepton pair forward backward asymmetry (FBA), lepton polarization asymmetries etc. In this model the contributions from Wilson coefficients $C_{Q_{1,2}}^\prime$, among new contributions, are dominant. Our results show that the NHB effects are sensitive to the FBA, $dL/d\hat{s}$, and $dT/d\hat{s}$ of $B \to K^{(*)} \tau^+ \tau^-$ decay, which are expected to be measured in B factories, and the average of the normal polarization $dN/d\hat{s}$ can reach several percent for $B \to K \mu^+ \mu^-$ and it is 0.05 or so for $B\to K \tau^+\tau^-$, which could be measured in the future super B factories and provide a useful information to probe new physics and discriminate different models.Comment: 16 pages,7 figure

Unified picture for Dirac neutrinos, dark matter, dark energy and matter-antimatter asymmetry

We propose a unified scenario to generate the masses of Dirac neutrinos and cold dark matter at the TeV scale, understand the origin of dark energy and explain the matter-antimatter asymmetry of the universe. This model can lead to significant impact on the Higgs searches at LHC.Comment: 5 pages, 3 figures. Title changed. Abstract, introduction and summary revised. References added. Model and conclusion unchange

The See-Saw Mechanism, Neutrino Yukawa Couplings, LFV Decays l_i to l_j + gamma and Leptogenesis

The LFV charged lepton decays mu to e + gamma, tau to e + gamma and tau to mu + gamma and thermal leptogenesis are analysed in the MSSM with see-saw mechanism of neutrino mass generation and soft SUSY breaking with universal boundary conditions. The case of hierarchical heavy Majorana neutrino mass spectrum, M_1 10^9 GeV. Considering the natural range of values of the heaviest right-handed Majorana neutrino mass, M_3 > 5*10^{13} GeV, and assuming that the soft SUSY breaking universal gaugino and/or scalar masses have values in the range of few 100 GeV, we derive the combined constraints, which the existing stringent upper limit on the mu to e + gamma decay rate and the requirement of successful thermal leptogenesis impose on the neutrino Yukawa couplings, heavy Majorana neutrino masses and SUSY parameters. Results for the three possible types of light neutrino mass spectrum -- normal and inverted hierarchical and quasi-degenerate -- are obtained.Comment: 25 pages, 9 figures; typos corrected, few clarifying comments and one figure added; version submitted for publicatio