Causality in Time-Neutral Cosmologies

Gell-Mann and Hartle (GMH) have recently considered time-neutral cosmological models in which the initial and final conditions are independently specified, and several authors have investigated experimental tests of such models. We point out here that GMH time-neutral models can allow superluminal signalling, in the sense that it can be possible for observers in those cosmologies, by detecting and exploiting regularities in the final state, to construct devices which send and receive signals between space-like separated points. In suitable cosmologies, any single superluminal message can be transmitted with probability arbitrarily close to one by the use of redundant signals. However, the outcome probabilities of quantum measurements generally depend on precisely which past {\it and future} measurements take place. As the transmission of any signal relies on quantum measurements, its transmission probability is similarly context-dependent. As a result, the standard superluminal signalling paradoxes do not apply. Despite their unusual features, the models are internally consistent. These results illustrate an interesting conceptual point. The standard view of Minkowski causality is not an absolutely indispensable part of the mathematical formalism of relativistic quantum theory. It is contingent on the empirical observation that naturally occurring ensembles can be naturally pre-selected but not post-selected.Comment: 5 pages, RevTeX. Published version -- minor typos correcte

Inverted Hybrid Inflation as a solution to gravitino problems in Gravity Mediation

It was recently found that the decay of inflaton and the SUSY breaking field produces many gravitinos in the gravity mediation scenario. These discoveries led to an exclusion of many inflation models such as chaotic, (smooth) hybrid, topological and new inflation models. Under these circumstances we searched for a successful inflation model and found that the ``inverted'' hybrid inflation models can solve the gravitino overproduction problem by their distinctive shape of the potential. Furthermore, we found that this inflation model simultaneously can explain the observed baryon asymmetry through the non-thermal leptogenesis and is consistent with the WMAP results, that is, $n_s=0.951^{+0.015}_{-0.019}$ and the negligible tensor to scalar ratio.Comment: 23 pages, 2 figures in

Higgs potential in S_3 invariant model for quark/lepton mass and mixing

We analyzed the S_3 invariant Higgs potential with S_3 singlet and doublet Higgs. We obtained a relation (|v_1|/|v_2|)^2=-sin2phi_2/sin2phi_1 from this S_3 invariant Higgs potential, where v_1, v_2 and phi_1, phi_2 are vacuum pectation values and phases of S_3 doublet Higgs, respectively. This relation could be satisfied exactly by the results |v_1|/ |v_2|=0.207, phi_1=-74.9deg and phi_2=0.74deg obtained from the previous our work analyzing the quark/lepton mass and mixing in S_3 invariant Yukawa interaction. Furthermore, the relation v_S ~ v_D=sqrt{|v_1|^2+|v_2|^2}=174GeV is obtained and then the coupling strength of Higgs to top quark g_{H_Stt}=m_t/v_S is altered as by a factor sqrt{2} from the standard value. Introduced the S_3 doublet Higgs, FCNC are produced in tree level. Predicted branching ratios for rare decays mu^- to e^-e^+e^-, K^0_L to mu^+\mu^- etc., induced by the FCNC are sufficiently below the present experimental upper bounds.Comment: 16 pages, 3 figure

R-invariant New Inflation Model vs Supersymmetric Standard Model

We revisit the implications of the R-invariant New Inflation model to the supersymmetric standard model in light of recent discussion of gravitino production processes by the decay of the inflaton or the supersymmetry breaking field. We show that the models with supergravity mediation do not go well with the R-invariant New Inflation model, where the gravitino abundance produced by the decay of the inflaton or the supersymmetry breaking field significantly exceeds the bounds from cosmological observations without fine-tuning. We also show that the models with gauge mediation can go together with R-invariant New Inflation model, where the dark matter and the baryon asymmetry are consistently explained without severe fine-tuning.Comment: 19 pages, 3 figure

Decoherent Histories Quantum Mechanics with One 'Real' Fine-Grained History

Decoherent histories quantum theory is reformulated with the assumption that there is one "real" fine-grained history, specified in a preferred complete set of sum-over-histories variables. This real history is described by embedding it in an ensemble of comparable imagined fine-grained histories, not unlike the familiar ensemble of statistical mechanics. These histories are assigned extended probabilities, which can sometimes be negative or greater than one. As we will show, this construction implies that the real history is not completely accessible to experimental or other observational discovery. However, sufficiently and appropriately coarse-grained sets of alternative histories have standard probabilities providing information about the real fine-grained history that can be compared with observation. We recover the probabilities of decoherent histories quantum mechanics for sets of histories that are recorded and therefore decohere. Quantum mechanics can be viewed as a classical stochastic theory of histories with extended probabilities and a well-defined notion of reality common to all decoherent sets of alternative coarse-grained histories.Comment: 11 pages, one figure, expanded discussion and acknowledgment

N K and Delta K states in the chiral SU(3) quark model

The isospin I=0 and I=1 kaon-nucleon $S$, $P$, $D$, $F$ wave phase shifts are studied in the chiral SU(3) quark model by solving the resonating group method (RGM) equation. The calculated phase shifts for different partial waves are in agreement with the experimental data. Furthermore, the structures of the $\Delta K$ states with L=0, I=1 and I=2 are investigated. We find that the interaction between $\Delta$ and $K$ in the case of L=0, I=1 is attractive, which is not like the situation of the $NK$ system, where the $S$-wave interactions between $N$ and $K$ for both I=0 and I=1 are repulsive. Our numerical results also show that when the model parameters are taken to be the same as in our previous $NN$ and $YN$ scattering calculations, the $\Delta K$ state with L=0 and I=1 is a weakly bound state with about 2 MeV binding energy, while the one with I=2 is unbound in the present one-channel calculation.Comment: 14 pages, 6 figures. PRC70,064004(2004

Asymptotically scale-invariant occupancy of phase space makes the entropy Sq extensive

Phase space can be constructed for $N$ equal and distinguishable subsystems that could be (probabilistically) either {\it weakly} (or {\it "locally"}) correlated (e.g., independent, i.e., uncorrelated), or {\it strongly} (or {\it globally}) correlated. If they are locally correlated, we expect the Boltzmann-Gibbs entropy $S_{BG} \equiv -k \sum_i p_i \ln p_i$ to be {\it extensive}, i.e., $S_{BG}(N)\propto N$ for $N \to\infty$. In particular, if they are independent, $S_{BG}$ is {\it strictly additive}, i.e., $S_{BG}(N)=N S_{BG}(1), \forall N$. However, if the subsystems are globally correlated, we expect, for a vast class of systems, the entropy $S_q\equiv k [1- \sum_i p_i^q]/(q-1)$ (with $S_1=S_{BG}$) for some special value of $q\ne1$ to be the one which extensive (i.e., $S_q(N)\propto N$ for $N \to\infty$).Comment: 15 pages, including 9 figures and 8 Tables. The new version is considerably enlarged with regard to the previous ones. New examples and new references have been include

Orbifold Family Unification in SO(2N) Gauge Theory

We study the possibility of family unification on the basis of SO(2N) gauge theory on the five-dimensional space-time, $M^4\times S^1/Z_2$. Several SO(10), $SU(4) \times SU(2)_L \times SU(2)_R$ or SU(5) multiplets come from a single bulk multiplet of SO(2N) after the orbifold breaking. Other multiplets including brane fields are necessary to compose three families of quarks and leptons.Comment: 28 page

Gauged Discrete Symmetries and Proton Stability

We discuss the results of a search for anomaly free Abelian Z_N discrete symmetries that lead to automatic R-parity conservation and prevents dangerous higher-dimensional proton decay operators in simple extensions of the minimal supersymmetric extension of the standard model (MSSM) based on the left-right symmetric group, the Pati-Salam group and SO(10). We require that the superpotential for the models have enough structures to be able to give correct symmetry breaking to MSSM and potentially realistic fermion masses. We find viable models in each of the extensions and for all the cases, anomaly freedom of the discrete symmetry restricts the number of generations.Comment: 8 pages, 2 figures; v2 : typos fixed, references adde

Energy scale independence of Koide's relation for quark and lepton masses

Koide's mass relation of charged leptons has been extended to quarks and neutrinos, and we prove here that this relation is independent of energy scale in a huge energy range from $1 {GeV}$ to $2\times10^{16} {GeV}$. By using the parameters $k_u$, $k_d$ and $k_{\nu}$ to describe the deviations of quarks and neutrinos from the exact Koide's relation, we also check the quark-lepton complementarity of masses such as $k_{l}+k_{d} \approx k_{\nu}+k_{u} \approx 2$, and show that it is also independent (or insensitive) of energy scale.Comment: 16 Latex pages, 2 figures, final version to appear in PR