We present a generic ${\mathbb{Z}}_2\times {\mathbb{Z}}_2$-invariant scalar field theory with four real scalar fields in six-dimensional Minkowskian spacetime which yields solutions consisting of two intersecting domain-wall kinks which are each paired by fields with lumplike profiles. For a special parameter choice, analytic solutions can be obtained. We show that the ${\mathbb{Z}}_2\times {\mathbb{Z}}_2$ symmetry can be maintained while coupling fermions by introducing scalar Yukawa couplings to one kink-lump pair and six-dimensional pseudoscalar Yukawa couplings to the other, and we show that there exists a zero mode localized to the domain-wall junction in this case. We also show that scalar fields can be localized.

We study the consistency of two Higgs doublet models in light of the new bosonic particle discovery at the LHC. We work within a general setup that we call here the general two Higgs doublet model, in which the quarks couple to both scalar doublets with aligned couplings such that flavor-changing neutral currents are absent at tree level. The framework encompasses the traditional type I, type II, lepton specific, and flipped models but also provides for more general possibilities. The best fit to the current data is given in the general scenario with specific parameter choices; however, a good fit is also obtained within a democratic model in which both the up-type and down-type quarks couple to each doublet with equal strengths. The approach provides a general framework in which to interpret future LHC Higgs data within extensions of the Standard Model with two Higgs doublets.

We present a formulation of domain-wall fermions in the Schrödinger functional by following a universality argument. To examine the formulation, we numerically investigate the spectrum of the free operator and perform a one-loop analysis to confirm universality and renormalizability. We also study the breaking of the Ginsparg-Wilson relation to understand the structure of chiral symmetry breaking from two sources: the bulk and the boundary. Furthermore, we discuss the lattice artifacts of the step scaling function by comparing with other fermion discretizations.

The model is presented to describe the $f_2(1270)$ meson photoproduction as a result of pion-pion interactions in the final state. Treating tensor mesons as objects dynamically created due to final state interactions is a convenient and straightforward way to employ data from $\pi \pi$ scattering like phase shifts and inelasticities for description of (photo)production reactions while retaining proper analytical structure of amplitudes, two-particle unitarity, and crossing symmetry. The model presented here can provide experimentally testable quantities like differential cross sections and $\pi \pi$ mass distributions as well as the strengths of partial waves corresponding to various $f_2(1270)$ helicities which are essential for partial wave analyses. It can also be used to compute moments of angular distribution and spin density matrix elements where partial wave interference effects are important.

We study the formation of inhomogeneous order in the Einstein-Maxwell-axion system, dual to a ($2+1$)–dimensional field theory that exhibits a spontaneously generated current density, momentum density and modulated scalar operator. Below the critical temperature, the Reissner-Nordström-AdS black hole becomes unstable, and stripes form in the bulk and on the boundary. The bulk geometry possesses striking geometrical features, including a modulated horizon that tends to pinch off as $T\to 0$. On a domain of fixed length, we find a second-order phase transition to the striped solution in each of the grand canonical, canonical and microcanonical ensembles, with modulated charges that grow and saturate as we lower the temperature and descend into the inhomogeneous phase. For the black hole on an infinite domain, a similar second-order transition occurs, and the width of the dominant stripe increases in the zero-temperature limit.

We study the dynamical stripe instabilities on the geometries with hyperscaling violation in the IR, which asymptotically approach ${\mathrm{AdS}}_4$ in the UV. The instabilities break the translational invariance spontaneously and are induced by the axion term $\sim aF\wedge F$ in the bulk action. We first study the perturbation equations in the probe limit, and find that there is a strong correlation between the stripe instabilities caused by the axion term and parameters of the theories which determine the IR hyperscaling violation. Contrary to the IR ${\mathrm{AdS}}_2$ case, the effect of the axion term for the stripe instabilities can be enhanced/suppressed at low temperature depending on the parameters. For a certain one-parameter family of the hyperscaling violation, we find the onset of the stripe instability analytically in the axion coupling tuned model. For a more generic parameter range of hyperscaling violation, we study the instability onset by searching for the zero mode numerically on the full geometries. We also argue that quite analogous results hold after taking into account the graviton fluctuation, i.e., beyond the probe limit.

We investigate minimally completed models of extraordinary gauge mediation, which are examples of direct gauge mediation, at finite temperature both analytically and numerically. These models may have both supersymmetry breaking and supersymmetric vacua. Our interest is in determining the preferred vacuum. We do so by computing the finite temperature Coleman-Weinberg potential and studying its thermal evolution.

Diquarks with $J^P=0^{\pm }$, $1^{\pm }$ containing a heavy (charm or bottom) quark and a light quark are investigated using QCD Laplace sum rules. Masses are determined using appropriately constructed gauge invariant correlation functions, including for the first time next-to-leading order perturbative contributions. The $J^P=0^{+}$ and $1^{+}$ charm-light diquark masses are, respectively, found to be $1.86\pm 0.05$ and $1.87\pm 0.10\mathrm{GeV}$, while those of the $0^{+}$ and $1^{+}$ bottom-light diquarks are both determined to be $5.08\pm 0.04\mathrm{GeV}$. The sum rules derived for heavy-light diquarks with negative parity are poorly behaved and do not permit unambiguous mass predictions, in agreement with previous results for negative parity light diquarks. The scalar and axial vector heavy-light diquark masses are degenerate within uncertainty, as expected by heavy quark symmetry considerations. Furthermore, these mass predictions are in good agreement with masses extracted in constituent diquark models of the tetraquark candidates $X(3872)$ and $Y_b(10890)$. Thus these results provide QCD support for the interpretation of the $X(3872)$ and $Y_b(10890)$ as $J^{\mathrm{PC}}=1^{++}$ tetraquark states composed of diquark clusters. Further implications for tetraquarks among the heavy quarkoniumlike XYZ states are discussed.

We investigate the $a$ theorem for nonsupersymmetric gauge-Yukawa theories beyond the leading order in perturbation theory. The exploration is first performed in a model-independent manner and then applied to a specific relevant example. Here, a rich fixed point structure appears including the presence of a merging phenomenon between nontrivial fixed points for which the $a$ theorem has not been tested so far.

We examine the numerical solutions of a field theoretic model to better understand the role played by the poles associated with the ambiguity identified by Castillejo, Dalitz, and Dyson (CDD). By analytically analyzing the numerical solutions to the crossing-symmetric Chew-Low model previously found, we show that the solutions are unique. This is done by requiring a second solution that would reproduce the original threshold and resonance. This uniqueness applies to the family of solutions, found by varying the parameters, that produces a resonance. The $T$ matrix for this model is not a generalized $R$ function. and no analogy can be made to the CDD analysis. Adding a CDD pole to the solution would constitute a new model, so there is no CDD ambiguity. None of the family of solutions from this new model will reproduce the original threshold and resonance. We also find that one cannot treat an individual channel as an $R$ function, nor can one add a CDD pole to an individual channel alone. Both a pole and a crossed pole must be added to all channels to maintain crossing symmetry. Crossing symmetry analytically connects all of the channels. The Chew-Low model being phenomenological is more pertinent to modern field theoretic models.

We consider the idea of modeling a rotating acoustic black hole by an idealized draining bathtub vortex which is a planar circulating flow phenomenon with a sink at the origin. We find the acoustic metric for this phenomenon from a noncommutative Abelian Higgs model. As such the acoustic metric not only describes a rotating acoustic black hole but also inherits the noncommutative characteristic of the spacetime. We address the issues of superresonance and analogue Aharonov-Bohm (AB) effect in this background. We mainly show that the scattering of planar waves by a draining bathtub vortex leads to a modified AB effect and due to spacetime noncommutativity, the phase shift persists even in the limit where the parameters associated with the circulation and draining vanish. Finally, we also find that the analogue AB effect and superresonance are competing phenomena at a noncommutative spacetime.

We study a planar four-Fermi Gross-Neveu model in the presence of a tilted magnetic field, with components parallel and perpendicular to the system’s plane. We determine how this combination of magnetic field components, when applied simultaneously, affects the phase diagram of the model. It is shown that each component of the magnetic field causes a competing effect on the chiral symmetry in these fermionic systems. While the perpendicular component of the magnetic field tends to make the chiral symmetry breaking stronger, the effect of the parallel component of the field in these planar systems is to weaken the chiral symmetry through the enhancement of the Zeeman energy term. We show that this competing effect, when combined also with temperature and chemical potential, can lead to a rich phase diagram, with the emergence of multiple critical points and reentrant phase transitions. We also study how the presence of these multiple critical points and reentrant phases can manifest in the quantum Hall effect. Our results provide a possible way to probe experimentally chiral symmetry breaking and the corresponding emergence of a gap (i.e., the presence of a nonvanishing chiral vacuum expectation value) in planar condensed matter systems of current interest.

We explore the possibility of testing modified gravity exhibiting the Vainshtein mechanism against observations of cluster lensing. We work in the most general scalar-tensor theory with second-order field equations (Horndeski’s theory), and derive static and spherically symmetric solutions, for which the scalar field is screened below a certain radius. It is found that the essential structure of the problem in the most general case can be captured by the program of classifying Vainshtein solutions out of different solutions to a quintic equation, as has been performed in the context of massive gravity. The key effect on gravitational lensing is that the second derivative of the scalar field can substantially be large at the transition from screened to unscreened regions, leaving a dip in the convergence. This allows us to put observational constraints on parameters characterizing the general scalar-tensor modification of gravity. We demonstrate how this occurs in massive gravity as an example, and discuss its observational signatures in cluster lensing.

Loop quantum cosmology with a scalar field is known to be closely linked with an inflationary phase. In this article, we study probabilistic predictions for the duration of slow-roll inflation, by assuming a minimalist massive scalar field as the main content of the Universe. The phase of the field in its “prebounce” oscillatory state is taken as a natural random parameter. We find that the probability for a given number of inflationary e-folds is quite sharply peaked around 145, which is consistent with the most favored minimum values. In this precise sense, a satisfactory inflation is therefore a clear prediction of loop gravity. In addition, we derive an original and stringent upper limit on the Barbero-Immirzi parameter. The general picture of inflation, superinflation, deflation, and superdeflation is also much clarified in the framework of bouncing cosmologies.

In this paper we study quantum dynamics of the bouncing cosmological model. We focus on the model of the flat Friedmann-Robertson-Walker universe with a free scalar field. The bouncing behavior, which replaces the classical singularity, appears due to the modification of general relativity using the methods of loop quantum cosmology. We show that there exists a unitary transformation that enables one to describe the system as a free particle with a Hamiltonian equal to the canonical momentum. We examine properties of the various quantum states of the universe: the boxcar state, the standard coherent state, and the soliton-like state, as well as Schrödinger’s cat states constructed from these states. Characteristics of the states—such as quantum moments and Wigner functions—are investigated. We show that each of these states have, for some range of parameters, a proper semiclassical limit fulfilling the correspondence principle. The decoherence of the superposition of two universes is described and possible interpretations in terms of triad orientation and the Belinsky-Khalatnikov-Lifshitz conjecture are given. We also examine negative-part sectors of the Wigner functions for the considered states. Their respective areas and localizations in the phase space feature an adequate estimate of nonclassicality. In particular, we show that regions where the Wigner function for the Glauber coherent cat state assumes its negative values have area equal to one fourth of the Planck constant. Based on the examined examples, we also conjecture that regions with negative values for the Wigner function are never smaller than one fourth of the Planck constant for states satisfying the uncertainty principle.

We complete the analytical determination, at the 4th post-Newtonian approximation, of the main radial potential describing the gravitational interaction of two bodies within the effective one-body formalism. The (nonlogarithmic) coefficient $a_5(\nu )$ measuring this 4th post-Newtonian interaction potential is found to be linear in the symmetric mass ratio $\nu$. Its $\nu$-independent part $a_5(0)$ is obtained by an analytical gravitational self-force calculation that unambiguously resolves the formal infrared divergencies which currently impede its direct post-Newtonian calculation. Its $\nu$-linear part $a_5(\nu )-a_5(0)$ is deduced from recent results of Jaranowski and Schäfer, and is found to be significantly negative.

The ATLAS Collaboration published supersymmetry limits based on up to about $4.7{\mathrm{fb}}^{-1}$ data collected over the year 2011 from LHC runs at 7 TeV. These were mainly interpreted within restricted, particular or simplified models for supersymmetry breaking schemes or scenarios. The phenomenological MSSM (pMSSM) is an alternative and more generic supersymmetry framework that captures broader phenomenological features. Searching for more generic conclusions from the supersymmetry limits interpretation, we update a Bayesian global fit of the pMSSM to pre-LHC data using the LHC-7 limits. The posterior distributions show the most up-to-date features, revealing allowed versus excluded regions in sparticle mass planes within the MSSM.

The contribution of the $R$-parity violating trilinear couplings in the supersymmetric model to the fermion electric dipole moment is analyzed at the two-loop level. We show that in general, the Barr-Zee type contribution to the fermion electric dipole moment with the exchange of $W$ and $Z$ bosons is not small compared to the currently known photon exchange one with $R$-parity violating interactions. We will then give new upper bounds on the imaginary parts of $R$-parity violating couplings from the experimental data of the electric dipole moments of the electron and of the neutron. The effect due to bilinear $R$-parity violating couplings, which needs to be investigated separately, is not included in our analyses.

We present the first global analysis of the constrained next-to-minimal supersymmetric standard model that investigates the impact of the recent discovery of a 126 GeV Higgs-like boson, of the observation of a signal for branching ratio $\mathrm{BR}({\mathrm{B}}_{\mathrm{s}}\to {\mu }^{+}{\mu }^{-})$, and of constraints on supersymmetry from $\sim 5/\mathrm{fb}$ of data accumulated at the LHC, as well as of other relevant constraints from colliders, flavor physics and dark matter. We consider three possible cases, assuming in turn that the discovered Higgs boson is (i) the lightest Higgs boson of the model; (ii) the next-to-lightest Higgs boson; and (iii) a combination of both roughly degenerate in mass. The likelihood function for the Higgs signal uses signal rates in the $\gamma \gamma$ and $ZZ\to 4l$ channels, while that for the Higgs exclusion limits assumes decay through the $\gamma \gamma$, $\tau \tau$, $ZZ$ and $W^{+}{W}^{-}$ channels. In all cases considered we identify the 68% and 95% credible posterior probability regions in a Bayesian approach. We find that, when the constraints are applied with their respective uncertainties, the first case shows strong CMSSM-like behavior, with the stau coannihilation region featuring highest posterior probability, the best-fit point, a correct mass of the lightest Higgs boson and the lighter top squark mass in the ballpark of 1 TeV. We also expose in this region a linear relationship between the trilinear couplings of the stau and the top squark, with both of them being strongly negative as enforced by the Higgs mass and the relic density, which outside of the stau coannihilation region show some tension. The second and the third case, on the other hand, while allowed are disfavored by the constraints from direct detection of dark matter and from $\mathrm{BR}({\mathrm{B}}_{\mathrm{s}}\to {\mu }^{+}{\mu }^{-})$. Without the anomalous magnetic moment of the muon the fit improves considerably, especially for negative effective $\mu$ parameter. We discuss how the considered scenarios could be tested further at the LHC and in dark matter searches.