We list scalar leptoquarks which mediate proton decay via renormalizable couplings to the standard model fermions. We employ a general basis of baryon number violating operators to parametrize contributions of each leptoquark towards proton decay. This then sets the stage for investigation of bounds on the leptoquark couplings to fermions with respect to the most current Super Kamiokande results on proton stability. We quantify if, and when, it is necessary to have leptoquark masses close to a scale of grand unification in the realistic $SU(5)$ and flipped $SU(5)$ frameworks. The most and the least conservative lower bounds on the leptoquark masses are then presented. We furthermore single out a leptoquark without phenomenologically dangerous tree-level exchanges which might explain discrepancy of the forward-backward asymmetries in $t\overline{t}$ production observed at Tevatron, if relatively light. The same state could also play a significant role in explaining muon anomalous magnetic moment. We identify contributions of this leptoquark to dimension-six operators, mediated through a box diagram, and tree-level dimension-nine operators, which would destabilize the proton if sizable leptoquark and diquark couplings were to be simultaneously present.

We present an SU(12) unification model with three light chiral families, avoiding any external flavor symmetries. The hierarchy of quark and lepton masses and mixings is explained by higher dimensional Yukawa interactions involving Higgs bosons that contain SU(5) singlet fields with vacuum expectation values about 50 times smaller than the SU(12) unification scale. The presented model has been analyzed in detail and found to be in very good agreement with the observed quark and lepton masses and mixings.

Production in association with an electroweak vector boson $V$ is a distinctive mode of production for a Higgs boson $H$ without tree-level couplings to fermions, known as a fermiophobic Higgs boson. We focus on $HV$ associated production with $H$ decay into a pair of photons, and $V$ into a pair of jets, with the goal of distinguishing a fermiophobic Higgs boson from the standard model Higgs boson. Performing a simulation of the signal and pertinent QCD backgrounds, and using the same event selection cuts employed by the LHC ATLAS Collaboration, we argue that existing LHC data at 7 TeV with $4.9{\mathrm{fb}}^{-1}$ of integrated luminosity may distinguish a fermiophobic Higgs boson from a standard model Higgs boson near 125 GeV at about 1.9 standard deviation signal significance ($1.9\sigma$) per experiment. At 8 TeV we show that associated production could yield $2.8\sigma$ significance per experiment with $10{\mathrm{fb}}^{-1}$ of data.

We report on a high statistics lattice QCD calculation of the mass of the $\eta$ and ${\eta }^{\prime }$ mesons using ASQTAD improved staggered fermions. The calculation used two ensembles with different lattice spacings and pion masses. We also report results for $\eta \mathrm{\text{−}}{\eta }^{\prime }$ mixing. The results are in satisfactory agreement with other lattice calculations using other fermion formulations and with experiment, given the unphysical quark masses used. We see no evidence of abnormal behavior at the lattice spacings studied.

The Belle Collaboration has recently reported a study of the decays $B\to D_{s1}(2536{)}^{+}{\overline{D}}^{(*)}$ and has also given estimates of relevant ratios between branching fractions of decays $B\to D^{(*)}{D}_{sJ}^{(*)}$ providing important information to check the structure of the $D_{s0}^{*}(2317)$, $D_{s1}(2460)$, and $D_{s1}(2536)$ mesons. The disagreement between experimental data and heavy quark symmetry has been used as an indication that $D_{s0}^{*}(2317)$ and $D_{s1}(2460)$ mesons could have a more complex structure than the canonical $c\overline{s}$ one. We analyze these ratios within the framework of a constituent quark model, which allows us to incorporate the effects given by finite $c$-quark mass corrections. Our findings are that while the $D_{s1}(2460)$ meson could have a sizable non-$q\overline{q}$ component, the $D_{s0}^{*}(2317)$ and $D_{s1}(2536)$ mesons seem to be well described by a pure $q\overline{q}$ structure.

In this paper, we numerically study the forward correlations between the lepton pair and associated hadrons in the Drell-Yan process in $\mathrm{p}A$ collisions. Using the present knowledge of the dipole gluon distribution from the modified Golec-Biernat-Wüsthoff model and from the solution of the Balitsky-Kovchegov evolution equation, we are able to compute and predict the forward correlations between the lepton pair and associated hadron in the Drell-Yan process at the RHIC and LHC. Similar to the forward dihadron correlation in d–Au collisions measured at the RHIC, the Drell-Yan type correlation also implies a strong suppression of the away side hadron at forward rapidity due to the strong interaction between the forward quark from the projectile proton and the gluon density from the target nucleus. Another feature of this process is that the correlation contains a double-peak structure in the away side, which makes it a unique observable.

Nonstrange hexaquark state $q^3{\overline{q}}^3$ spectrum is systematically studied by using the Gaussian expansion method in flux tube models with a six-body confinement potential. All the model parameters are fixed by baryon properties, so the calculation of hexaquark state $q^3{\overline{q}}^3$ is parameter-free. It is found that some ground states of $q^3{\overline{q}}^3$ are stable against disintegrating into a baryon and an anti-baryon. The main components of $X(1835)$ and $X(2370)$, which are observed in the radiative decay of $J/\psi$ by BES collaboration, can be described as compact hexaquark states $N_8{\overline{N}}_8$ and ${\Delta }_8{\overline{\Delta }}_8$ with quantum numbers $I^G{J}^{PC}=0^{+}{0}^{-+}$, respectively. These bound states should be color confinement resonances with three-dimensional configurations similar to a rugby ball, however, $X(2120)$ can not be accommodated in this model approach.

Rising interest in nuclear reactors as a source of antineutrinos for experiments motivates validated, fast, and accessible simulations to predict reactor fission rates. Here we present results from the DRAGON and MURE simulation codes and compare them to other industry standards for reactor core modeling. We use published data from the Takahama-3 reactor to evaluate the quality of these simulations against the independently measured fuel isotopic composition. The propagation of the uncertainty in the reactor operating parameters to the resulting antineutrino flux predictions is also discussed.

We consider extensions of the standard model inspired by intersecting D-brane constructions, in order to address flavor mass textures. We include additional anomalous gauge symmetries, and scalar fields to break them and to generate Froggatt-Nielsen mass terms. Green-Schwarz axions are included to cancel mixed anomalies rendering the models consistent. At low energies, a residual anomalous global symmetry remains, and its associated pseudo-Goldstone mode becomes the physical axion, which can be interpreted as an axion arising from open string modes. General considerations show that such axions are very common in D-brane models and can be completely incompatible with current bounds. Astrophysical constraints are placed on the axion both by including neutrino masses in the Froggatt-Nielsen scheme and considering QCD instanton contributions to the axion mass. We find simple models where the axion decay constant is in the allowed range, but only one such minimal model with this property is free from excessive fine tunings elsewhere. We also note that generically addressing flavor textures for the Cabibbo-Kobayashi-Maskawa matrix leads to deconstructed extra dimensions.

We develop the representation of bulk fields with spin one and spin two in anti-de Sitter space, as nonlocal observables in the dual CFT. Working in holographic gauge in the bulk, at leading order in $1/N$ bulk gauge fields are obtained by smearing boundary currents over a sphere on the complexified boundary, while linearized metric fluctuations are obtained by smearing the boundary stress tensor over a ball. This representation respects AdS covariance up to a compensating gauge transformation. We also consider massive vector fields, where the bulk field is obtained by smearing a nonconserved current. We compute bulk two-point functions and show that bulk locality is respected. We show how to include interactions of massive vectors using $1/N$ perturbation theory, and we comment on the issue of general backgrounds.

It is often emphasized that spin-foam models could realize a projection on the physical Hilbert space of canonical loop quantum gravity. As a first test, we analyze the one-vertex expansion of a simple Euclidean spin foam. We find that for fixed Barbero-Immirzi parameter $\gamma =1$, the one-vertex amplitude in the Kaminski, Kisielowski, and Lewandowski prescription annihilates the Euclidean Hamiltonian constraint of loop quantum gravity [T. Thiemann, Classical Quantum Gravity 15, 839 (1998).]. Since, for $\gamma =1$, the Lorentzian part of the Hamiltonian constraint does not contribute, this gives rise to new solutions of the Euclidean theory. Furthermore, we find that the new states only depend on the diagonal matrix elements of the volume. This seems to be a generic property when applying the spin-foam projector.

Path integrals appear to offer natural and intuitively appealing methods for defining quantum-mechanical amplitudes for questions involving spacetime regions. For example, the amplitude for entering a spatial region during a given time interval is typically defined by summing over all paths between given initial and final points but restricting them to pass through the region at any time. We argue that there is, however, under very general conditions, a significant complication in such constructions. This is the fact that the concrete implementation of the restrictions on paths over an interval of time corresponds, in an operator language, to sharp monitoring at every moment of time in the given time interval. Such processes suffer from the quantum Zeno effect—the continual monitoring of a quantum system in a Hilbert subspace prevents its state from leaving that subspace. As a consequence, path integral amplitudes defined in this seemingly obvious way have physically and intuitively unreasonable properties and, in particular, no sensible classical limit. In this paper we describe this frequently occurring but little-appreciated phenomenon in some detail, showing clearly the connection with the quantum Zeno effect. We then show that it may be avoided by implementing the restriction on paths in the path integral in a “softer” way. The resulting amplitudes then involve a new coarse-graining parameter, which may be taken to be a time scale $ϵ$, describing the softening of the restrictions on the paths. We argue that the complications arising from the Zeno effect are then negligible as long as $ϵ\gg 1/E$, where $E$ is the energy scale of the incoming state.

In this work, we present a class of geometries which describes wormholes in a Randall-Sundrum brane model, focusing on de Sitter backgrounds. Maximal extensions of the solutions are constructed and their causal structures are discussed. A perturbative analysis is developed, where matter and gravitational perturbations are studied. Analytical results for the quasinormal spectra are obtained and an extensive numerical survey is conducted. Our results indicate that the wormhole geometries presented are stable.

In paper I (Yu et al. [1]), we showed through $N$-body simulation that a local monotonic Gaussian transformation can significantly reduce non-Gaussianity in a noise-free lensing convergence field. This makes the Gaussianization a promising theoretical tool to understand high-order lensing statistics. Here we present a study of its applicability in lensing data analysis, in particular when shape measurement noise is presented in lensing convergence maps. (i) We find that shape measurement noise significantly degrades the Gaussianization performance and the degradation increases for shallower surveys. (ii) The Wiener filter is efficient in reducing the impact of shape measurement noise. The Gaussianization of the Wiener-filtered lensing maps is able to suppress skewness, kurtosis, and the 5th- and 6th-order cumulants by a factor of 10 or more. It also works efficiently to reduce the bispectrum to zero.

We examine bounds on adiabatic and isocurvature density fluctuations from $\mu$-type spectral distortions of the CMB. Studies of such distortions are complementary to CMB measurements of the spectral index and its running and will help to constrain these parameters on significantly smaller scales. We show that a detection on the order of $\mu \sim {10}^{-7}$ would strongly be at odds with the standard cosmological model of a nearly scale-invariant spectrum of adiabatic perturbations. Further, we find that given the current CMB constraints on the isocurvature mode amplitude, a nearly scale-invariant isocurvature mode (common in many curvaton models) cannot produce significant $\mu$ distortion. Finally, we show that future experiments will strongly constrain the amplitude of the isocurvature modes with a highly blue spectrum as predicted by certain axion models.

By actively distorting the cosmic microwave background (CMB) over our past light cone, cosmic strings are unavoidable sources of non-Gaussianity. Developing optimal estimators able to disambiguate a string signal from the primordial type of non-Gaussianity requires calibration over synthetic full sky CMB maps, which until now had been numerically unachievable at the resolution of modern experiments. In this paper, we provide the first high resolution full sky CMB map of the temperature anisotropies induced by a network of cosmic strings since the recombination. The map has about 200 million subarcminute pixels in the healpix format which is the standard in use for CMB analyses ($N_{\mathrm{side}}=4096$). This premiere required about 800 000 cpu-hours; it has been generated by using a massively parallel ray tracing method piercing through thousands of state of art Nambu-Goto cosmic string numerical simulations which pave the comoving volume between the observer and the last scattering surface. We explicitly show how this map corrects previous results derived in the flat sky approximation, while remaining completely compatible at the smallest scales.

In a recently proposed renormalizable model of neutrino mixing using the non-Abelian discrete symmetry $T_7$ in the context of a supersymmetric extension of the standard model with gauged $U(1{)}_{B-L}$, a correlation was obtained between ${\theta }_{13}$ and ${\theta }_{23}$ in the case where all four parameters are real. Here we consider one parameter to be complex, thus allowing for one Dirac $CP$ phase ${\delta }_{CP}$ and two Majorana $CP$ phases ${\alpha }_{1,2}$. We find a slight modification to this correlation as a function of ${\delta }_{CP}$. For a given set of input values of $\Delta m_{21}^2$, $\Delta m_{32}^2$, ${\theta }_{12}$, and ${\theta }_{13}$, we obtain ${sin}^{2}2{\theta }_{23}$ and $m_{ee}$ (the effective Majorana neutrino mass in neutrinoless double beta decay) as functions of $\tan {\delta }_{CP}$. We find that the structure of this model always yields small $|\tan {\delta }_{CP}|$.

Recently we have shown by Monte Carlo simulation that an expanding ($3+1$)-dimensional universe appears dynamically from a Lorentzian matrix model for type IIB superstring theory in ($9+1$) dimensions. Here we study the classical equation of motion as a complementary approach. While the Monte Carlo results represent the behavior at earlier times, the classical equation of motion is expected to be valid at later times. In particular, we find a class of SO(3) symmetric solutions, which exhibits the time-dependence compatible with the expanding universe, while having no spatial noncommutativity. Based on this result, we speculate that the spatial noncommutativity, which plays a crucial role in the spontaneous breaking of rotational symmetry, vanishes at later times due to some dynamical mechanism.

Upper bounds on fundamental length are discussed that follow from the fact that a magnetic moment is inherent in a charged particle in noncommutative (NC) electrodynamics. The strongest result thus obtained for the fundamental length is still larger than the estimate of electron or muon size achieved following the Brodsky-Drell and Dehlmet approach to lepton compositeness. This means that NC electrodynamics cannot alone explain the whole existing discrepancy between the theoretical and experimental values of the muon magnetic moment. On the contrary, as measurements and calculations are further improved, the fundamental length estimate based on electron data may go down to match its compositeness radius.

The Ward identity in gauge theory constrains the behavior of the amplitudes. We discuss the Ward identity for amplitudes with a pair of shifted lines with complex momenta. This will induce a recursion relation identical to Britto-Cachazo-Feng-Witten recursion relations at the finite poles of the complexified amplitudes. Furthermore, according to the Ward identity, it is also possible to transform the boundary term into a simple form, which can be obtained by a new recursion relation. For the amplitude with one off-shell line in pure Yang-Mills theory, we find this technique is effective for obtaining the amplitude even when there are boundary contributions.