Current predictions for the ratio of $\varphi \to K^{+}{K}^{-}/K_L{K}_S$ decay rates exceed the corresponding experimental value in about 5 standard deviations. By far, the dominant sources of isospin breaking to this ratio are the phase-space (52%) and the electromagnetic radiative (4.3%, computed within scalar QED) corrections. Here we estimate the effects of the electromagnetic structure of kaons and other model-dependent contributions into the radiative corrections.

We investigate the constraints of dark matter search experiments on the different candidates emerging from the minimal quasiconformal strong coupling theory with fermions in the adjoint representation. For one candidate, the current limits of CDMS exclude a tiny window of masses around 120 GeV. We also investigate under what circumstances the newly proposed candidate composed of a $-2$ negatively charged particle and a ${}^4\mathrm{He}^{+2}$ can explain the discrepancy between the results of the CDMS and DAMA experiments. We found that this type of dark matter should give negative results in CDMS, while it can trigger the detectors of DAMA, if a condition between the mass and the binding energy of the $-2$ particle with the nucleus of the detector is satisfied.

We calculate the strength of the electroweak phase transition in a supersymmetric model with four chiral generations. The additional chiral fermions (and scalar partners) lower the critical temperature and thus strengthen the first-order phase transition. The scalar partners stabilize the potential, leading to an effective theory that is bounded from below. We identify the ensemble of parameters where ${\varphi }_c/T_c\gtrsim 1$ simultaneous with obtaining a large enough Higgs mass. Our calculations focus on a subset of the full four generational supersymmetric parameter space: We take the pseudoscalar heavy, $\tan \beta =1$, and neglect all subleading contributions to the effective potential. We find that the region of parameter space with a strong first-order phase transition requires $m_{{\tilde{q}}^{\prime }}/m_{q^{\prime }}\lesssim 1.1$ while the constraint on the lightest Higgs mass requires $m_{{\tilde{q}}^{\prime }}/m_{q^{\prime }}\gtrsim 1$ with $m_{q^{\prime }}\gtrsim 300\mathrm{GeV}$. We are led to an intriguing prediction of quarks and squarks just beyond the current Tevatron direct search limits that are poised to be discovered quickly at the LHC.

In this paper, the electromagnetic mass differences of heavy hadrons are discussed, while the relevant hyperfine interactions are ignored. The effects of one-photon exchange interaction and up-down quark mass difference are parametrized. Two mass difference equations $2{\Sigma }_c^{+}-({\Sigma }_c^{++}+{\Sigma }_c^0)=2{\Sigma }_b^0-({\Sigma }_b^{+}+{\Sigma }_b^{-})$ and $({\Xi }_{cc}^{+}-{\Xi }_{cc}^{++})+({\Xi }_{bb}^{-}-{\Xi }_{bb}^0)=2({\Xi }_{bc}^0-{\Xi }_{bc}^{+})$ for the heavy baryons are obtained. In addition, the masses of ${\Sigma }_b^0$, ${\Xi }_b^0$, and ${\Xi }_{cc}^{++}$ are predicted based on the known experimental data.

There are some radiative origins for the neutrino masses in the conventional left-right symmetric models with the usual bidoublet and triplet Higgs scalars. These radiative contributions could dominate over the tree-level seesaw and could explain the observed neutrino masses.

We study $B^0\to {\rho }^0{\rho }^0$ decays in a sample of $465\times {10}^6$ ${\rm Y}(4S)\to B\overline{B}$ events collected with the BABAR detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ collider located at the Stanford Linear Accelerator Center (SLAC). We measure the branching fraction $\mathcal{B}=(0.92\pm 0.32\pm 0.14)\times {10}^{-6}$ and longitudinal polarization fraction $f_L={0.75}_{-0.14}^{+0.11}\pm 0.05$, where the first uncertainty is statistical and the second is systematic. The evidence for the $B^0\to {\rho }^0{\rho }^0$ signal has a significance of 3.1 standard deviations, including systematic uncertainties. We investigate the proper-time dependence of the longitudinal component in the decay and measure the $CP$-violating coefficients $S_L^{00}=(0.3\pm 0.7\pm 0.2)$ and $C_L^{00}=(0.2\pm 0.8\pm 0.3)$. We study the implication of these results for the unitarity triangle angle $\alpha$.

Recent evidence appears to confirm that the ultra-high-energy primary cosmic ray spectrum consists mostly of protons. The fact that these protons can traverse large distances to reach Earth allows us to place bounds on Lorentz violations. The protons neither emit vacuum Cerenkov radiation nor $\beta$-decay into neutrons, and this constrains six previously unmeasured coefficients in the neutron sector at the $5\times {10}^{-14}$ level. Among the coefficients bounded here for the first time are those that control spin-independent boost anisotropy for neutrons. This is a phenomenon which could have existed (in light of the preexisting bounds) without additional fine-tuning. There are also similar bounds for others species of hadrons. The bounds on Lorentz violation for neutral pions are particularly strong, at the $4\times {10}^{-21}$ level, eleven orders of magnitude better than previous constraints.

We derive analytic solutions of a chameleon scalar field $\varphi$ that couples to a nonrelativistic matter in the weak gravitational background of a spherically symmetric body, paying particular attention to a field mass $m_A$ inside of the body. The standard thin-shell field profile is recovered by taking the limit $m_A{r}_c\to \infty$, where $r_c$ is a radius of the body. We show the existence of “no-shell” solutions where the field is nearly frozen in the whole interior of the body, which does not necessarily correspond to the “zero-shell” limit of thin-shell solutions. In the no-shell case, under the condition $m_A{r}_c\gg 1$, the effective coupling of $\varphi$ with matter takes the same asymptotic form as that in the thin-shell case. We study experimental bounds coming from the violation of equivalence principle as well as solar-system tests for a number of models including $f(R)$ gravity and find that the field is in either the thin-shell or the no-shell regime under such constraints, depending on the shape of scalar-field potentials. We also show that, for the consistency with local gravity constraints, the field at the center of the body needs to be extremely close to the value ${\varphi }_A$ at the extremum of an effective potential induced by the matter coupling.

We study the difficulties associated with the evaluation of the total Bondi momentum at finite distances around the central source of a general (asymptotically flat) spacetime. Since the total momentum is only rigorously defined at future null infinity, both finite distance and gauge effects must be taken into account for a correct computation of this quantity. Our discussion is applicable in general contexts but is particularly relevant in numerically constructed spacetimes for both extracting important physical information and assessing the accuracy of additional quantities.

We study the evolution of homogeneous and isotropic, flat cosmological models within the general scalar-tensor theory of gravity with arbitrary coupling function and potential. After introducing the limit of general relativity we describe the details of the phase space geometry. Using the methods of dynamical systems for the decoupled equation of the Jordan frame scalar field we find the fixed points of flows in two cases: potential domination and matter domination. We present the conditions on the mathematical form of the coupling function and potential which determine the nature of the fixed points (attractor or other). There are two types of fixed points, both are characterized by cosmological evolution mimicking general relativity, but only one of the types is compatible with the Solar System parametrized post-Newtonian (PPN) constraints. The phase space structure should also carry over to the Einstein frame as long as the transformation between the frames is regular which however is not the case for the latter (PPN compatible) fixed point.

We study the thermodynamics of massless ${\varphi }^4$-theory using screened perturbation theory. In this method, the perturbative expansion is reorganized by adding and subtracting a thermal mass term in the Lagrangian. We calculate the free energy through four loops expanding in a double power expansion in $m/T$ and $g^2$, where $m$ is the thermal mass and $g$ is the coupling constant. The expansion is truncated at order $g^7$ and the loop expansion is shown to have better convergence properties than the weak-coupling expansion. The free energy at order $g^6$ involves the four-loop triangle sum-integral evaluated by Gynther, Laine, Schröder, Torrero, and Vuorinen using the methods developed by Arnold and Zhai. The evaluation of the free energy at order $g^7$ requires the evaluation of a nontrivial three-loop sum-integral, which we calculate by the same methods.

We examine the nature of electroweak Baryogenesis when the Higgs boson’s properties are modified by the effects of new physics. We utilize the effective potential to one loop (ring improving the finite temperature perturbative expansion), while retaining parametrically enhanced dimension six operators of $\mathcal{O}(v^2/f^2)$ in the Higgs sector. These parametrically enhanced operators would be present if the Higgs is a pseudo-Goldstone boson of a new physics sector with a characteristic mass scale $\Lambda \sim \mathrm{TeV}$, a coupling constant $4\pi \ge g\ge 1$, and a strong decay constant scale $f=\Lambda /g$. We find that generically the effect of new physics of this form allows a sufficiently first order electroweak phase transition so that the produced Baryon number can avoid washing out, and has enhanced effects due to new sources of $CP$ violation. We also improve the description of the electroweak phase transition in perturbation theory by determining the thermal mass eigenstate basis of the standard model gauge boson fields. This improves the calculation of the finite temperature effects through incorporating mixing in the determination of the vector boson thermal masses of the standard model. These effects are essential to determining the nature of the phase transition in the standard model and are of interest in our pseudo-Goldstone Baryogenesis scenario.

We confront the $R$-parity violating minimal supersymmetric standard model with the neutrino oscillation data. Investigating the 1-loop particle-sparticle diagrams with additional bilinear insertions on the external neutrino lines we construct the relevant contributions to the neutrino mass matrix. A comparison of the so-obtained matrices with the experimental ones assuming normal or inverted hierarchy and taking into account possible $CP$-violating phases allows to set constraints on the values of the bilinear coupling constants. A similar calculation is presented with the input from the Heidelberg-Moscow neutrinoless double beta decay experiment. We base our analysis on the renormalization group evolution of the minimal supersymmetric standard model parameters which are unified at the grand unified theory scale. Using the obtained bounds we calculate the contributions to the Majorana neutrino transition magnetic moments.

We investigate the effect of supersymmetric (SUSY) threshold corrections on the values of the running quark and charged lepton masses at the grand unified theory (GUT) scale within the large $\tan \beta$ regime of the minimal supersymmetric standard model. In addition to the typically dominant SUSY QCD contributions for the quarks, we also include the electroweak contributions for quarks and leptons and show that they can have significant effects. We provide the GUT scale ranges of quark and charged lepton Yukawa couplings as well as of the ratios $m_{\mu }/m_s$, $m_e/m_d$, $y_{\tau }/y_b$ and $y_t/y_b$ for three example ranges of SUSY parameters. We discuss how the enlarged ranges due to threshold effects might open up new possibilities for constructing GUT models of fermion masses and mixings.

We compute the cross section for exclusive production of a photon associated with a heavy quarkonium $H$ of charge-conjugation parity $C=+1$ from $e^{+}{e}^{-}$ annihilation into a virtual photon at the center-of-momentum energy $\sqrt{s}=10.58\mathrm{GeV}$. The nonrelativistic QCD factorization formulas for the differential and total cross sections are obtained at leading order in the strong coupling and in the relative velocity of the heavy quark in the quarkonium rest frame. The predicted cross sections for the $S$-wave spin-singlet cases are about 80 fb and 50 fb for $H={\eta }_c$ and ${\eta }_c(2S)$, respectively. Among $P$-wave spin-triplet charmonia, ${\chi }_{c1}$ has a particularly large cross section of about 14 fb. The cross sections for bottomonium states ${\eta }_b$ and ${\chi }_{bJ}$ are about 3 fb. A rough estimate of the background reveals that the signal significances for charmonium processes are sufficiently large enough to be detected with ease with the integrated luminosities available at the present $B$ factories.

The classical notion of a single-particle scalar distribution function or phase space density can be generalized to a matrix in order to accommodate superpositions of states of discrete quantum numbers, such as neutrino mass/flavor. Such a “neutrino distribution matrix” is thus an appropriate construct to describe a neutrino gas that may vary in space as well as time and in which flavor mixing competes with collisions. The Liouville equations obeyed by relativistic neutrino distribution matrices, including the spatial derivative and vacuum flavor mixing terms, can be explicitly but elegantly derived in two new ways: from a covariant version of the familiar simple model of flavor mixing, and from the Klein-Gordon equations satisfied by a quantum “density function” (mean value of paired quantum field operators). Associated with the latter derivation is a case study in how the joint position/momentum dependence of a classical gas (albeit with Fermi statistics) emerges from a formalism built on quantum fields.

There exists a well-known problem with the ${}^7\mathrm{Li}+{}^7\mathrm{Be}$ abundance predicted by standard big bang nucleosynthesis being larger than the value observed in population II stars. The catalysis of big bang nucleosynthesis by metastable, ${\tau }_X\gtrsim {10}^3\sec$, charged particles $X^{-}$ is capable of suppressing the primordial ${}^7\mathrm{Li}+{}^7\mathrm{Be}$ abundance and making it consistent with the observations. We show that to produce the correct abundance, this mechanism of suppression places a requirement on the initial abundance of $X^{-}$ at temperatures of $4\times {10}^8\mathrm{K}$ to be on the order of or larger than 0.02 per baryon, which is within the natural range of abundances in models with metastable electroweak-scale particles. The suppression of ${}^7\mathrm{Li}+{}^7\mathrm{Be}$ is triggered by the formation of (${}^7\mathrm{Be}{X}^{-}$) compound nuclei, with fast depletion of their abundances by catalyzed proton reactions, and in some models by direct capture of $X^{-}$ on ${}^7\mathrm{Be}$. The combination of ${}^7\mathrm{Li}+{}^7\mathrm{Be}$ and ${}^6\mathrm{Li}$ constraints favors the window of lifetimes, $1000\mathrm{s}\lesssim {\tau }_X\le 2000\mathrm{s}$.

The order parameter of a finite system with a spontaneously broken continuous global symmetry acts as a quantum mechanical rotor. Both antiferromagnets with a spontaneously broken $SU(2{)}_s$ spin symmetry and massless QCD with a broken $SU(2{)}_L\times SU(2{)}_R$ chiral symmetry have rotor spectra when considered in a finite volume. When an electron or hole is doped into an antiferromagnet or when a nucleon is propagating through the QCD vacuum, a Berry phase arises from a monopole field and the angular momentum of the rotor is quantized in half-integer units.

Effects of the vector-type four-quark interaction on QCD phase structure are investigated in the imaginary chemical potential ($\mu$) region, by using the Polyakov-loop extended Nambu–Jona-Lasinio model with the extended ${\mathbb{Z}}_3$ symmetry. We clarify analytically the Roberge-Weiss periodicity and symmetry properties of various quantities under the existence of a vector-type four-quark interaction. In the imaginary $\mu$ region, the chiral condensate and the quark-number density are sensitive to the strength of the interaction. Based on this result, we propose a possibility to determine the strength of the vector-type interaction, which largely affects QCD phase structure in the real $\mu$ region, by comparing the results of lattice simulations and effective model calculations in the imaginary $\mu$ region.

The standard model predictions for the hadronic electric dipole moments (EDMs) are well far from the present experimental resolutions, thus, the EDMs represent very clean probes of New Physics (effects. Especially, within a minimal supersymmetric standard model framework with flavor-changing (but not necessarily $CP$-violating) soft terms, large and potentially visible effects to the EDMs are typically expected. In this paper we point out that, beyond-leading-order effects, so far neglected in the literature, dominate over the leading-order effects in large regions of the parameter space; hence, their inclusion in the evaluation of the hadronic EDMs is unavoidable.