We propose a model with one large sub-mm size extra dimension in which the gravity and right-handed neutrino propagate, but the three standard model (SM) families are confined to fat branes of ${\mathrm{TeV}}^{-1}$ size or smaller. The charged leptons and the light neutrinos receive mass from the five-dimensional Yukawa couplings with the SM singlet neutrino via electroweak Higgs, while the Kaluza-Klein excitations of the SM singlet neutrino gets large TeV scale masses from the five-dimensional Yukawa coupling with an electroweak singlet Higgs. The model gives nonhierarchical light neutrino masses, accommodates hierarchical charged lepton masses, and naturally explains why the light neutrino masses are so much smaller compared to the charged lepton masses. Large neutrino mixing is naturally expected in this scenario. The light neutrinos are Dirac particles in this model, hence neutrinoless double beta decay is not allowed. The model also has several interesting collider implications and can be tested at the LHC.

We study, in a bottom-up approach, the fine-tuning problem between soft supersymmetry (SUSY) breaking parameters and the $\mu$ term for the successful electroweak symmetry breaking in the minimal supersymmetric standard model. It is shown that certain ratios among nonuniversal gaugino masses at the grand unified theory (GUT) scale are necessary to reduce fine-tuning. In addition, when all the gaugino masses are regarded as independent ones in their origins, a small gluino mass $M_3\lesssim 120\mathrm{GeV}$ and a nonvanishing $A$ term $A_t\sim O(M_3)$ associated with top squarks are also required at the GUT scale as well as the nonuniversality. On the other hand, when we consider some UV theory, which fixes ratios of soft SUSY breaking parameters as certain values aside from the overall magnitude, heavier spectra are allowed. It is favored that the gluino and $W$-ino masses are almost degenerate at the weak scale, while a wider region of $b$-ino mass is favorable.

We analyze the branching ratios of $B\to D^{(*)}{D}_{s0}^{*}(D_{s1})$ decays using the factorization hypothesis. The $B\to D^{(*)}$ transition form factors are taken from a model-independent analysis done by Caprini, Lellouch, and Neubert based on heavy quark spin symmetry and dispersive constraints, including short-distance and power corrections. The leptonic decay constants $f_{D_{s0}^{*}}$ and $f_{D_{s1}}$ are calculated assuming a molecular structure for the $D_{s0}^{*}$ and $D_{s1}$ mesons. The calculated branching ratios of $B$-meson two-body decays are compared with experimental data and other theoretical results.

We present a detailed analysis together with numerical calculations on one-loop contributions to the neutron, deuteron, and mercury electric dipole moment from supersymmetry without $R$ parity, focusing on the quark-scalar loop contributions. Being proportional to top Yukawa and top mass, such contributions are often large, and since these are proportional to hitherto unconstrained combinations of bilinear and trilinear $R$-parity violating (RPV) parameters, they are all the more interesting. Complete formulas are given for the various contributions through the quark dipole operators including the contribution from the color dipole operator. The contribution from the color dipole operator is found to be a similar order in magnitude when compared to the electric dipole operator and should be included in any consistent analysis. Analytical expressions illustrating the explicit role of the $R$-parity violating parameters are given following perturbative diagonalization of mass-squared matrices for the scalars. Dominant contributions come from the combinations $B_i^{*}{\lambda }_{ij1}^{\prime }$ for which we obtain robust bounds. It turns out that neutron and deuteron electric dipole moments (EDMs) receive much stronger contributions than the mercury EDM and any null result at the future deuteron EDM experiment or Los Alamos neutron EDM experiment can lead to extraordinary constraints on RPV parameter space. Even if $R$-parity violating couplings are real, Cabibbo-Kobayashi-Maskawa (CKM) phase does induce RPV contribution and for some cases such a contribution is as strong as the contribution from phases in the $R$-parity violating couplings. Hence, we have bounds directly on $|B_i^{*}{\lambda }_{ij1}^{\prime }|$ even if the RPV parameters are all real. Interestingly, even if slepton mass and/or ${\mu }_0$ is as high as 1 TeV, it still leads to neutron EDM that is an order of magnitude larger than the sensitivity at the Los Alamos experiment. Since the results are not much sensitive to $\tan \beta$, our constraints will survive even if other observables tighten the constraints on $\tan \beta$.

We present the first observation of the decay $B^{+}\to {\rho }^{+}{K}^0$, using a data sample of $348{\mathrm{fb}}^{-1}$ collected at the ${\rm Y}(4S)$ resonance with the BABAR detector. The branching fraction and charge asymmetry are measured to be $({8.0}_{-1.3}^{+1.4}\pm 0.6)\times {10}^{-6}$ and $(-12.2\pm 16.6\pm 2.0)\%$, respectively, where the first uncertainty is statistical and the second is systematic. The charge asymmetry is defined by ${\mathcal{A}}_{\mathrm{ch}}=({\Gamma }_{B^{-}}-{\Gamma }_{B^{+}})/({\Gamma }_{B^{-}}+{\Gamma }_{B^{+}})$ with ${\Gamma }_{B^{\pm }}$ the $B^{\pm }$ decay rate. The significance of the observed branching fraction, including systematic uncertainties, is 7.9 standard deviations.

Using $385{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collisions, we study the amplitudes of the singly Cabibbo-suppressed decay $D^0\to K^{-}{K}^{+}{\pi }^0$. We measure the strong phase difference between the ${\overline{D}}^0$ and $D^0$ decays to $K^{*}(892{)}^{+}{K}^{-}$ to be $-35.5°\pm 1.9°(\mathrm{stat})\pm 2.2°(\mathrm{syst})$, and their amplitude ratio to be $0.599\pm 0.013(\mathrm{stat})\pm 0.011(\mathrm{syst})$. We observe contributions from the $K\pi$ and $K^{-}{K}^{+}$ scalar and vector amplitudes, and analyze their angular moments. We find no evidence for charged $\kappa$, nor for higher spin states. We also perform a partial-wave analysis of the $K^{-}{K}^{+}$ system in a limited mass range.

This paper derives a set of general relativistic cardinal equations for the equilibrium of an extended body in a uniform gravitational field. These equations are essential for a proper understanding of the mechanics of suspended relativistic systems. As an example, the prototypical case of a suspended vessel filled with radiation is discussed. The mechanics of Casimir apparatuses at rest in the gravitational field of the Earth is then considered. Starting from an expression for the Casimir energy-momentum tensor in a weak gravitational field recently derived by the authors, it is shown here that, in the case of a rigid cavity supported by a stiff mount, the weight of the Casimir energy $E_C$ stored in the cavity corresponds to a gravitational mass $M=E_C/c^2$, in agreement with the covariant conservation law of the regularized energy-momentum tensor. The case of a cavity consisting of two disconnected plates supported by separate mounts, where the two measured forces cannot be obtained by straightforward arguments, is also discussed.

In previous work done by us and coworkers, we have been able to construct a local, non-Abelian gauge invariant action with a mass parameter, based on the nonlocal gauge invariant mass dimension two operator $F_{\mu \nu }(D^2{)}^{-1}{F}_{\mu \nu }$. The renormalizability of the resulting action was proven to all orders of perturbation theory, in the class of linear covariant gauges. We also discussed the perturbative equivalence of the model with ordinary massless Yang-Mills gauge theories when the mass is identically zero. Furthermore, we pointed out the existence of a Becchi-Rouet-Stora-Tyutin (BRST) symmetry with corresponding nilpotent charge. In this paper, we study the issue of unitarity of this massive gauge model. First, we provide a short review how to discuss the unitarity making use of the BRST charge. Afterwards we make a detailed study of the most general version of our action, and we come to the conclusion that the model is not unitary, as we are unable to remove all the negative norm states from the physical spectrum in a consistent way.

We present a detailed calculation of the electron-positron production rate using neutrinos in an intense background magnetic field. The computation is done for the process $\nu \to \nu e\overline{e}$ (where $\nu$ can be ${\nu }_e$, ${\nu }_{\mu }$, or ${\nu }_{\tau }$) within the framework of the standard model. Results are given for various combinations of Landau levels over a range of possible incoming neutrino energies and magnetic field strengths.

Doubt continues to linger over the reality of quantum vacuum energy. There is some question whether fluctuating fields gravitate at all, or do so anomalously. Here we show that, for the simple case of parallel conducting plates, the associated Casimir energy gravitates just as required by the equivalence principle, and that therefore the inertial and gravitational masses of a system possessing Casimir energy $E_c$ are both $E_c/c^2$. This simple result disproves recent claims in the literature. We clarify some pitfalls in the calculation that can lead to spurious dependences on the coordinate system.

We outline the nonlinear transformation in the path integral representation for partition function of $O(N)$ symmetric oscillator systems bringing their duality to certain one-dimensional oscillators with unstable potential shapes. This duality transformation realizes the equivalence between spectra of a Hermitian and a non-Hermitian Hamiltonian. It is exploited to calculate exactly the spectra of quantum rotators. The zero-temperature limit is considered and the dual representation of $n$-point correlators of coordinate operators is obtained.

We study gravitational collapse of a spherically symmetric scalar field in Einstein-aether theory (general relativity coupled to a dynamical unit timelike vector field). The initial value formulation is developed, and numerical simulations are performed. The collapse produces regular, stationary black holes, as long as the aether coupling constants are not too large. For larger couplings a finite area singularity occurs. These results are shown to be consistent with the stationary solutions found previously.

The holographic dark energy model is proposed by Li as an attempt for probing the nature of dark energy within the framework of quantum gravity. The main characteristic of holographic dark energy is governed by a numerical parameter $c$ in the model. The parameter $c$ can only be determined by observations. Thus, in order to characterize the evolving feature of dark energy and to predict the fate of the Universe, it is of extraordinary importance to constrain the parameter $c$ by using the currently available observational data. In this paper, we derive constraints on the holographic dark energy model from the latest observational data including the gold sample of 182 type Ia supernovae (SNIa), the shift parameter of the cosmic microwave background (CMB) given by the three-year Wilkinson Microwave Anisotropy Probe (WMAP) observations, and the baryon acoustic oscillation (BAO) measurement from the Sloan Digital Sky Survey (SDSS). The joint analysis gives the fit results in $1\mathrm{\text{−}}\sigma$: $c={0.91}_{-0.18}^{+0.26}$ and ${\Omega }_{\mathrm{m}0}=0.29\pm 0.03$. That is to say, though the possibility of $c<1$ is more favored, the possibility of $c>1$ cannot be excluded in one-sigma error range, which is somewhat different from the result derived from previous investigations using earlier data. So, according to the new data, the evidence for the quintom feature in the holographic dark energy model is not as strong as before.

In a supersymmetric axion model where the scale for both supersymmetry breaking and Peccei-Quinn symmetry breaking is around ${10}^{11}\mathrm{GeV}$, we find that there is a reasonable parameter space for a strongly first order phase transition at the scale.

We calculate the form factors for the semileptonic decays of heavy-light pseudoscalar mesons in partially quenched staggered chiral perturbation theory ($\mathrm{S}\chi \mathrm{PT}$), working to leading order in $1/m_Q$, where $m_Q$ is the heavy-quark mass. We take the light meson in the final state to be a pseudoscalar corresponding to the exact chiral symmetry of staggered quarks. The treatment assumes the validity of the standard prescription for representing the staggered “fourth-root trick” within $\mathrm{S}\chi \mathrm{PT}$ by insertions of factors of $1/4$ for each sea-quark loop. Our calculation is based on an existing partially quenched continuum chiral perturbation theory calculation with degenerate sea quarks by Bećirević, Prelovsek, and Zupan, which we generalize to the staggered (and nondegenerate) case. As a byproduct, we obtain the continuum partially quenched results with nondegenerate sea quarks. We analyze the effects of nonleading chiral terms, and find a relation among the coefficients governing the analytic valence mass dependence at this order. Our results are useful in analyzing lattice computations of form factors $B\to \pi$ and $D\to K$, when the light quarks are simulated with the staggered action.

The first search for the rare kaon decay $K_L\to {\pi }^0{\pi }^0\nu \overline{\nu }$ has been performed by the E391a collaboration at the KEK 12-GeV proton synchrotron. An upper limit of $4.7\times {10}^{-5}$ at the 90% confidence level was set for the branching ratio of the decay $K_L\to {\pi }^0{\pi }^0\nu \overline{\nu }$ using about 10% of the data collected during the first period of data taking. First limits for the decay mode $K_L\to {\pi }^0{\pi }^{0}P$, where $P$ is a pseudoscalar particle, were also set.

Baryon number violation is discussed in gauge unified orbifold models of type II string theory with intersecting Dirichlet branes. We consider setups of $D6$-branes which extend along the flat Minkowski space-time directions and wrap around three cycles of the internal 6D manifold. Our study is motivated by the enhancement effect of low energy amplitudes anticipated for M theory and type II string theory models with matter modes localized at points of the internal manifold. The conformal field theory formalism is used to evaluate the open string amplitudes at tree level. We study the single baryon number violating processes of dimension 6 and 5, involving four quarks and leptons and in supersymmetry models, two pairs of matter fermions and superpartner sfermions. The higher order processes associated with the baryon number violating operators of dimension 7 and 9 are also examined, but in a qualitative way. We discuss the low energy representation of string theory amplitudes in terms of infinite series of poles associated to exchange of string Regge resonance and compactification modes. The comparison of string amplitudes with the equivalent field theory amplitudes is first studied in the large compactification radius limit. Proceeding next to the finite compactification radius case, we present a numerical study of the ratio of string to field theory amplitudes based on semirealistic gauge unified nonsupersymmetric and supersymmetric models employing the $Z_3$ and $Z_2\times Z_2$ orbifolds. We find a moderate enhancement of string amplitudes which becomes manifest in the regime where the gauge symmetry breaking mass parameter exceeds the compactification mass parameter, corresponding to a gauge unification in a seven dimensional space-time.

In this work we derive the covariant and gauge invariant perturbation equations in general theories of $f(R)$ gravity in the Palatini formalism to linear order and calculate the cosmic microwave background (CMB) and matter power spectra for an extensively discussed model, $f(R)=R+\alpha (-R{)}^{\beta }$, which is a possible candidate for the late-time cosmic accelerating expansion found recently. These spectra are discussed and found to be sensitively dependent on the value of $\beta$. We are thus able to make stringent constraints on $\beta$ from cosmological data on CMB and matter power spectra: The three-year Wilkinson Microwave Anisotropy Probe (WMAP) data alone give a constraint $|\beta |\lesssim \mathcal{O}({10}^{-3})$ while the joint WMAP, Supernova Lagacy Survey (SNLS), and Sloan Digital Sky Survey (SDSS) data sets tighten this to $\beta \sim \mathcal{O}({10}^{-6})$, about an order of magnitude more stringent than the constraint from SDSS data alone, which makes this model practically indistinguishable from the standard $\Lambda \mathrm{CDM}$ paradigm.

We present a computation of the next-to-leading order QCD corrections to the production of three $Z$ bosons at the Large Hadron Collider. We calculate these corrections using a completely numerical method that combines sector decomposition to extract infrared singularities with contour deformation of the Feynman parameter integrals to avoid internal loop thresholds. The NLO QCD corrections to $pp\to ZZZ$ are approximately 50% and are badly underestimated by the leading order scale dependence. However, the kinematic dependence of the corrections is minimal in phase space regions accessible at leading order.

Magnetic monopoles may be properly introduced in a Lorentz- and $CPT$-violating electrodynamics in $(3+1)\mathrm{D}$ whenever it is accompanied by the induction of an additional electric current, whose strength is proportional to the breaking parameter, $({\kappa }_{AF}{)}_{\mu }$. The reduced model is similar to the Maxwell-Chern-Simons model in $(2+1)\mathrm{D}$, with a Dirac-like object, so that in this case the mass parameter appears quantized. In addition, the electromagnetic force experienced by a magnetic pole bears an extra term, depending on $({\kappa }_{AF}{)}_{\mu }$, in comparison to its counterpart acting upon an electric charge.