We match the Higgs sector of the most general flavor-breaking and $CP$-violating minimal supersymmetric standard model (MSSM) onto a generic two-Higgs-doublet model, paying special attention to the definition of $\tan \beta$ in the effective theory. In particular, no $\tan \beta$-enhanced loop corrections appear in the relation to $\tan \beta$ defined in the $\overline{\mathrm{DR}}$ scheme in the MSSM. The corrections to the Higgs-mediated flavor-changing amplitudes, which result from this matching, are especially relevant for the $B_d$ and $B_s$ mass differences $\Delta M_{d,s}$ for minimal flavor violation, where the superficially leading contribution vanishes. We give a symmetry argument to explain this cancellation and perform a systematic study of all Higgs-mediated effects, including Higgs loops. The corrections to $\Delta M_s$ are at most 7% for $\mu >0$ and $M_A<600\mathrm{GeV}$ if constraints from other observables are taken into account. For $\mu <0$ they can be larger, but are always less than about 20%. Contrary to recent claims, we do not find numerically large contributions here, nor do we find any $\tan \beta$-enhanced contributions from loop corrections to the Higgs potential in $B^{+}\to {\tau }^{+}\nu$ or $B\to X_s\gamma$. We further update supersymmetric loop corrections to the Yukawa couplings, where we include all possible $CP$-violating phases and correct errors in the literature. The possible presence of $CP$-violating phases generated by Higgs exchange diagrams is briefly discussed as well. Finally, we provide improved values for the bag factors $P_1^{\mathrm{VLL}}$, $P_2^{\mathrm{LR}}$, and $P_1^{\mathrm{SLL}}$ at the electroweak scale.

We compute the six-dimensional hexagon integral with three nonadjacent external masses analytically. After a simple rescaling, it is given by a function of six dual conformally invariant cross ratios. The result can be expressed as a sum of 24 terms involving only one basic function, which is a simple linear combination of logarithms, dilogarithms, and trilogarithms of uniform degree three transcendentality. Our method uses differential equations to determine the symbol of the function, and an algorithm to reconstruct the latter from its symbol. It is known that six-dimensional hexagon integrals are closely related to scattering amplitudes in $\mathcal{N}=4$ super Yang-Mills theory, and we therefore expect our result to be helpful for understanding the structure of scattering amplitudes in this theory, in particular, at two loops.

We study entropy corrections due to thermal fluctuations for asymptotically anti-de Sitter black holes in the grand canonical ensemble. To leading order, these can be expressed in terms of the black hole response coefficients via fluctuation moments. We also analyze entropy corrections due to mass and charge fluctuations of R-charged black holes, and our results indicate an universality in the logarithmic corrections to charged anti-de Sitter black hole entropy in various dimensions.

Flavor constraints in a bosonic technicolor model are considered. We illustrate different sources for their origin, and emphasize, in particular, the role played by the vector states present in the technicolor model. This feature is the essential difference in comparison to an analogous model with two fundamental Higgs scalar doublets.

We consider the possibility that dark matter can communicate with the standard model fields via flavor interactions. We take the dark matter to belong to a “dark sector” which contains at least two types, or “flavors,” of particles and then hypothesize that the standard model fields and dark matter share a common interaction which depends on flavor. As, generically, interaction eigenstates and mass eigenstates need not coincide, we consider both flavor-changing and flavor-conserving interactions. These interactions are then constrained by meson decays, kaon mixing, and current collider bounds, and we examine their relevance for direct detection and the LHC.

A new particle’s interactions can be measured at colliders, by observing its associated production with standard model particles. We focus on the case of a collider-stable right-handed top squark and study the LHC sensitivities to its couplings to the photon, $Z$, and the Higgs boson. Such measurements determine the top squark’s charge, mixing angle, and coupling to the electroweak symmetry breaking sector. Determining these couplings can provide strong evidence for the supersymmetric solution to the hierarchy problem. Our analysis shows that the LHC has great prospects for measuring the photon and Higgs couplings but will require a very high luminosity to measure the $Z$ coupling.

We present a study of the experimental determination of the forward-backward asymmetry in the process $e^{+}{e}^{-}\to t\overline{t}$ and in the subsequent $t\to Wb$ decay, studied in the context of the International Linear Collider. This process probes the elementary couplings of the top quark to the photon, and the $Z$ and the $W$ bosons at a level of precision that is difficult to achieve at hadron colliders. Measurement of the forward-backward asymmetry requires excellent $b$ quark identification and determination of the quark charge. The study reported here is performed in the most challenging all-hadronic channel $e^{+}{e}^{-}\to b\overline{b}q\overline{q}q\overline{q}$. It includes realistic details of the experimental environment, a full Monte Carlo simulation of the detector, based on the Silicon Detector concept, and realistic event reconstruction. The forward-backward asymmetries are determined to a precision of approximately 1% for each of the two choices of beam polarization. We analyze the implications for the determination of the $t\overline{t}Z$ and $Wt\overline{b}$ couplings.

We study the holographic QCD in the hadronic medium by using the soft wall model. We discuss the Hawking-Page transition between Reissner-Nordström anti-de Sitter (AdS) black hole and thermal charged AdS of which the geometries correspond to deconfinement and confinement phases, respectively. We also present the numerical result of the vector and axial-vector meson spectra depending on the quark density.

We show that the Hartle-Hawking vacuum for any theory of interacting massive scalars on a fixed de Sitter background is both perturbatively well defined and stable in the IR. Correlation functions in this state may be computed on the Euclidean section and Wick rotated to Lorentz signature. The results are manifestly de Sitter-invariant and contain only the familiar UV singularities. More importantly, the connected parts of all Lorentz-signature correlators decay at large separations of their arguments. Our results apply to all cases in which the free Euclidean vacuum is well defined, including scalars with masses belonging to both the complementary and principal series of $SO(D,1)$. This suggests that interacting Quantum Field Theories in de Sitter—including higher spin fields—are perturbatively IR stable at least when i) the Euclidean vacuum of the zero-coupling theory exists and ii) corresponding Lorentz-signature zero-coupling correlators decay at large separations. This work has significant overlap with a paper by Stefan Hollands, which is being released simultaneously.

We perform a Fisher matrix calculation of the predicted uncertainties on estimates of the cosmic string tension $G\mu$ from upcoming observational data (namely, cosmic microwave background power spectra from the Planck satellite and an idealized future polarization experiment). We employ simulations that are more general than others commonly used in the literature, leaving the mean velocity of strings, correlation length of the string network, and wiggliness (which parametrizes smaller-scale structure along the strings) as free parameters that can be observationally measured. In a new code, StringFast, we implement a method for efficient computation of the $C_{\ell }$ spectra induced by a network of strings, which is fast enough to be used in Markov Chain Monte Carlo analyses of future data. Performing a calculation with the string parameters left free results in projected constraints on $G\mu$ that are larger than those obtained by fixing their values a priori, typically by a factor of $\sim 2–7$. We also find that, if $G\mu$ is equal to the current observational maximum, Planck will be able to make a confident detection of strings. However, if $G\mu$ is 2 orders of magnitude smaller, even a perfect, lensing-free measurement of polarization power spectra will not be able to detect a nonzero string tension at better than $2\sigma$ confidence.

The original littlest Higgs model with universal fermion couplings is found to be consistent with precision electroweak data but is strongly constrained by Tevatron limits on the predicted centi-weak $Z^{\prime }$ boson. A possible signal observed by the Collider Detector at Fermilab (CDF) at 240 GeV is consistent with the predicted $Z^{\prime }$, and a region below 150 GeV is largely unconstrained by collider data. LHC searches for narrow dilepton resonances below 500 GeV will have sufficient sensitivity to discover the $Z^{\prime }$ boson or to exclude the model over most of the range allowed by the electroweak fits.

The two-equation of state model is used to describe the hadron-quark phase transition in dense-hot matter formed in heavy-ion collisions. The nonlinear Walecka model is used to describe the hadronic phase. For the quark phase, the Nambu–Jona-Lasinio (NJL) model coupled to Polyakov-loop fields is used to include both the chiral and (de)confinement dynamics. The phase diagrams are derived from the Gibbs conditions and compared with the results obtained in the hadron-NJL model without confinement. As in the hadron-NJL case a first order transition is observed, but with a critical end point at much higher temperatures, a consequence of the confinement mechanism that reduces the degrees of freedom of the quark matter in proximity to the phase transition. Particular attention is devoted to the phase transition in isospin asymmetric matter. Interesting isospin effects are found at high baryon density and reduced temperatures, which are in fact also common to other quark models, like the MIT bag model and the NJL model. Some possible observational signals are suggested to probe in heavy-ion collision experiments at intermediate energies.

We study the role of the scalar resonances $f_0(1370)$, $f_0(1500)$, and $f_0(1710)$ in the strong and radiative three-body decays of $J/\psi$ with $J/\psi \to V+PP(\gamma \gamma )$ and $J/\psi \to \gamma +PP(VV)$, where $P(V)$ denotes a pseudoscalar (vector) meson. We assume that the scalars result from a glueball-quarkonium mixing scheme while the dynamics of the transition process is described in the phenomenological Lagrangian approach. The present data on $J/\psi \to V+PP$ are well-reproduced; predictions for the radiative processes serve as further tests of this scenario.

Split-complex fields usually appear in the context of Euclidean supersymmetry. In this paper, we propose that this can be generalized to the non-Euclidean case and that, in fact, the split-complex representation may be the most natural way to formulate the scalar fields of the five dimensional universal hypermultiplet. We supplement earlier evidence of this by studying a specific class of solutions and explicitly showing that it seems to favor this formulation. We also argue that this is directly related to the symplectic structure of the general hypermultiplet fields arising from nontrivial Calabi-Yau moduli. As part of the argument, we find new explicit instanton and 3-brane solutions coupled to the four scalar fields of the universal hypermultiplet.

Galileon theories are of considerable interest since they allow for stable violations of the null energy condition. Since such violations could have occurred during a high-energy regime in the history of our Universe, we are motivated to study supersymmetric extensions of these theories. This is carried out in this paper, where we construct generic classes of $\mathcal{N}=1$ supersymmetric Galileon Lagrangians. They are shown to admit nonequivalent stress-energy tensors and, hence, vacua manifesting differing conditions for violating the null energy condition. The temporal and spatial fluctuations of all component fields of the supermultiplet are analyzed and shown to be stable on a large number of such backgrounds. In the process, we uncover a surprising connection between conformal Galileon and ghost-condensate theories, allowing for a deeper understanding of both types of theories.

We have updated our evaluation of the hadronic contribution to the running of the QED fine structure constant using the recent precise measurements of the $e^{+}{e}^{-}$ annihilation at the center-of-mass (c.m.s.) energy region between 2.6 and 3.65 GeV performed by the BES collaboration. In the low-energy region, around the $\rho$ resonance, we include the recent measurements from the BABAR, CDM-2, KLOE, and SND collaborations. We obtain $\Delta {\alpha }_{\mathrm{had}}^{(5)}(s)=0.02750\pm 0.00033$ at $s=m_{\mathrm{Z}}^2$.

We consider the possibility of studying new physics that singles out the tau lepton at the LHC. We concentrate on the tau lepton charge asymmetry in ${\tau }^{+}{\tau }^{-}$ pair production as a tool to probe this physics beyond the standard model. We consider two generic scenarios for the new physics. We first study a nonuniversal $Z^{\prime }$ boson as an example of a new resonance that can single out tau leptons. We then consider vector lepto-quarks coupling the first-generation quarks with the third-generation leptons as an example of nonresonant new physics. We find that in both cases the charge asymmetry can be sufficiently sensitive to the new physics to provide useful constraints at the LHC.

We analyze the multiplicity distributions of charged particles at Tevatron ($p\overline{p}$) and LHC ($pp$) energies in the framework of the independent pair parton interactions model. It is shown that the number of soft pair parton interactions (and therefore the density of the partonic medium) is large and increases with energy. The mean multiplicity at each parton interaction grows also with energy. This growth depends on the width of the rapidity window. Similar conclusions are obtained in the multiladder exchange model.

We conjecture that all $CP$ violations (both Dirac and Majorana types) arise from a common origin in the neutrino seesaw. With this conceptually attractive and simple conjecture, we deduce that $\mu \mathrm{\text{−}}\tau$ breaking shares the common origin with all $CP$ violations. We study the common origin of $\mu \mathrm{\text{−}}\tau$ and $CP$ breaking in the Dirac mass matrix of seesaw Lagrangian (with right-handed neutrinos being $\mu \mathrm{\text{−}}\tau$ blind), which uniquely leads to inverted mass ordering of light neutrinos. We then predict a very different correlation between the two small $\mu \mathrm{\text{−}}\tau$ breaking observables ${\theta }_{13}-0°$ and ${\theta }_{23}-45°$, which can saturate the present experimental upper limit on ${\theta }_{13}$. This will be tested against our previous normal mass-ordering scheme by the ongoing oscillation experiments. We also analyze the correlations of ${\theta }_{13}$ with Jarlskog invariant and neutrinoless $\beta \beta$-decay observable. From the common origin of $CP$ and $\mu \mathrm{\text{−}}\tau$ breaking in the neutrino seesaw, we establish a direct link between the low energy $CP$ violations and the cosmological $CP$ violation for baryon asymmetry. With these we further predict a lower bound on ${\theta }_{13}$, supporting the ongoing probes of ${\theta }_{13}$ at Daya Bay, Double Chooz, and RENO experiments. Finally, we analyze the general model-independent ${\mathbb{Z}}_2\otimes {\mathbb{Z}}_2$ symmetry structure of the light neutrino sector, and map it into the seesaw sector, where one of the ${\mathbb{Z}}_2$’s corresponds to the $\mu \mathrm{\text{−}}\tau$ symmetry ${\mathbb{Z}}_2^{\mu \tau }$ and another the hidden symmetry ${\mathbb{Z}}_2^s$ (revealed in our previous work) which dictates the solar mixing angle ${\theta }_{12}$. We derive the physical consequences of this ${\mathbb{Z}}_2^s$ and its possible partial violation in the presence of $\mu \mathrm{\text{−}}\tau$ breaking (with or without the neutrino seesaw), regarding the ${\theta }_{12}$ determination and the correlation between $\mu \mathrm{\text{−}}\tau$ breaking observables.