The coupled processes—the $\pi \pi$ scattering and $\pi \pi \to K\overline{K}$ in the $I^G{J}^{PC}=0^{+}{0}^{++}$ channel—are analyzed (both separately and combined) in a model-independent approach based on analyticity and unitarity and using a uniformization procedure. We show that (1) a structure of the Riemann surface of the $S$ matrix for considered coupled processes must be allowed for calculating both amplitudes and resonance parameters, such as the mass and width; and (2) the combined analysis of coupled processes is needed as the analysis of only the $\pi \pi$ channel does not give correct values of resonance parameters even if the Riemann surface structure is included.

Recent results on Higgs searches at the LHC point toward the existence of a Higgs boson with mass of about 126 GeV whose diphoton decay rate tends to be larger than in the Standard Model. These results are in tension with natural minimal supersymmetric Standard Model scenarios: such a Higgs mass requires heavy (third-generation) squarks which reintroduce some amount of fine-tuning and in general the Higgs diphoton decay rate tends to follow the Standard Model result. In this paper we prove that these problems can be alleviated by introducing an extra supersymmetric triplet coupled to the Higgs in the superpotential. This superfield generates a sizeable tree-level correction to the Higgs mass so that the third generation is no longer required to be heavy, and its charged component enhances the diphoton Higgs decay rates by as much as 50% with respect to the Standard Model values. We also show that such a scenario is compatible with present electroweak precision observables.

We explore the phenomenology of a two-Higgs-doublet model (2HDM) where both Higgs doublets couple to up-type and down-type fermions with couplings determined by the minimal flavor violation (MFV) ansatz. This 2HDM ”type MFV” generalizes 2HDM types I–IV, where the decay rates of $h\to b\overline{b}$ and $h\to {\tau }^{+}{\tau }^{-}$ are governed by MFV couplings independent of the Higgs couplings to gauge bosons or the top quark. To determine the implications of the present Higgs data on the model, we have performed global fits to all relevant data. Several surprisingly large effects on the light Higgs phenomenology can arise: (1) The modified couplings of the Higgs to fermions can enhance the $h\to \gamma \gamma$ rate significantly in both vector boson fusion production (up to a factor of 3 or more) and the inclusive rate (up to a factor of 1.5 or more); (2) in the 2HDM type MFV, the constraints on a light charged Higgs are milder than in 2HDM types I–IV. Thus, there can be substantial charged Higgs loop contribution to the diphoton rate, allowing further enhancements of the diphoton rates; (3) the $h\to {\tau }^{+}{\tau }^{-}$ rate can be (highly) suppressed, independently of the other decay channels. Furthermore, we studied the correlation between the light Higgs and the heavy Higgs phenomenology. We showed that even small deviations from the decoupling limit would imply good prospects for the detection of the heavy Higgs boson. In some regions of parameter space, a substantial range of $M_H$ is already either ruled out or on the edge of detection. Finally, we investigated the possibility that the heavy Higgs is close in mass to the light Higgs, providing an additional $h/H\to b\overline{b}$ rate, as well as confounding the extraction of properties of the Higgs bosons.

Spurred by the discovery of a boson resonance at the LHC as the result of the search for the standard model Higgs boson, we pursue our investigation of the properties and signatures of Higgs bosons in an effective supersymmetric scenario that goes beyond the usual minimal supersymmetric standard model. Such scenarios were first introduced to alleviate the naturalness problem of the minimal supersymmetric standard model Higgs boson and are found to have a very rich phenomenology that allows departures from the standard model in the production rate of the Higgs boson in many of the search channels. We now include the constraints from flavor observables, in particular, the rare decays $B\to X_s^{*}\gamma$ and $B_s\to {\mu }^{+}{\mu }^{-}$ including the recent measurement from LHCb. We also address the issue of dark matter and its impact on Higgs physics. In particular, we incorporate the latest data from XENON100 on the spin independent direct detection rates. These turn out to be powerful constraints, especially if one also imposes that the observed thermal relic density is obtained. We also study models with a low abundance that can more easily evade the direct detection rates. Furthermore, we study the impact of the flavor and dark matter observables on the production rates of the Higgs boson at the LHC, and their correlations in the diphoton, $\mathrm{\text{diphoton}}+\mathrm{\text{jets}}$ and 4 leptons. We also comment on the other channels.

We investigate the scope of the LHC in probing the parameter space of a four-site model supplemented by one composite Higgs state, assuming all past, current and future energy and luminosity stages of the CERN machine. We concentrate on the yield of charged diboson production giving two opposite-charge different-flavor leptons and missing (transverse) energy, i.e., events induced via the subprocess $q\overline{q}\to e^{+}{\nu }_e{\mu }^{-}{\overline{\nu }}_{\mu }+\mathrm{c}.\mathrm{c}.$, which enables the production in the intermediate step of all additional neutral and charged gauge bosons belonging to the spectrum of this model, some of which are in resonant topologies. We find this channel accessible over the background at all LHC configurations after a dedicated cut-based analysis. We finally compare the yield of the diboson mode to that of Drell-Yan processes and establish that they have complementary strengths, one covering regions of parameter space precluded to the others and vice versa.

We propose an attractor mechanism which generates the more minimal supersymmetric standard model from a broad class of supersymmetry breaking boundary conditions. The hierarchies in the fermion masses and mixings are produced by the same dynamics and a natural weak scale results from gaugino mediation. These features arise from augmenting the standard model with a new $SU(3)$ gauge group under which only the third generation quarks are charged. The theory flows to a strongly interacting fixed point which induces a negative anomalous dimension for the third generation quarks and a positive anomalous dimension for the Higgs. As a result, a split-family natural spectrum and the flavor hierarchies are dynamically generated.

We find that a holographic walking technicolor model has a limit (“conformal limit”) where the technidilaton (TD) becomes a massless Nambu-Goldstone boson of the scale symmetry with its nonzero finite decay constant $F_{\varphi }\ne 0$, which naturally realizes a light TD, say at 125 GeV, near the limit. In such a light TD case, we find that $F_{\varphi }$ is uniquely determined by the technipion decay constant $F_{\pi }$ independently of the holographic parameters: $F_{\varphi }/F_{\pi }\simeq \sqrt{2N_{\mathrm{TF}}}$, with $N_{\mathrm{TF}}$ being the number of technifermions. We show that the holographic TD is consistent with a new boson at 125 GeV recently discovered at the LHC.

Threshold contributions to light scalar soft masses due to heavy sparticles (possibly including a heavy Higgs mostly aligned with $H_d$) in effective supersymmetry (SUSY) scenarios are dominated by two-loop diagrams involving gauge couplings. This is due to the fact that in the limit in which the heavy states are degenerate, their one-loop contributions to the light soft masses only depend on small Yukawas and the hypercharge coupling. The two-loop threshold corrections involving only gauge couplings are calculated accounting for nonzero gaugino and light squark masses and shown to be negative, and rather large ($\delta m_{t,L}^2\sim -{480}^2{\mathrm{GeV}}^2$ for heavy sparticles with masses around 10 TeV). The effect on tachyon bounds is revisited with calculations implementing decoupling. It is pointed out that models yielding Effective SUSY spectra using gaugino mediation require in general very heavy gluinos or a very low SUSY breaking scale in order to avoid tachyons (e.g., for heavy squarks at 10 TeV and a SUSY breaking scale of 125 TeV, minimal scenarios require $\widetilde{m_3}\gtrsim 2\mathrm{TeV}$ at 500 GeV, while nonminimal ones demand $\widetilde{m_3}\gtrsim 8\mathrm{TeV}$).

The charged Higgs boson phenomenology and discovery potential at future linear colliders through the production process $e^{-}{e}^{+}\to H^{+}{H}^{-}\to {\tau }^{+}\nu \tau \overline{\nu }$ is studied. Both charged Higgs bosons are considered to decay to $\tau \nu$, and the hadronic decay of $\tau$ leptons is analyzed, taking into account spin and kinematics effects using a proper simulation of the $\tau$-lepton decay. It is shown that within the minimal supersymmetric standard model framework, with $\tan \beta =10$, a wide range of charged Higgs masses would have a detectable signal beyond the $5\sigma$ statistical significance at linear colliders with $\sqrt{s}=500$ and 1000 GeV.

We investigate the constraints on the anomalous quartic $ZZ\gamma \gamma$ couplings through the process $pp\to p\gamma p\to p\gamma qZX$ at the LHC. Taking into consideration various forward detector acceptances and integrated LHC luminosities, we find 95% confidence level bounds on the anomalous coupling parameters. We show that the bounds on these couplings are at the order of ${10}^{-6}{\mathrm{GeV}}^{-2}$ which are about four orders of magnitude more restricted with respect to current experimental bounds.

We calculate the hadronic production of three heaviest bound baryons ${\Omega }_{bbb}$, ${\Omega }_{bbc}^{*}$, and ${\Omega }_{bbc}$ at hadron colliders at tree level. We present the integrated cross section and differential cross section distributions in this paper.

Infrared behavior of the Landau gauge gluon propagators is studied numerically in the 3D $SU(2)$ gauge theory on the lattice. A special accent is made on the study of Gribov copy effect. For this study we employ an efficient gauge-fixing algorithm and a large number of gauge copies (up to 280 copies per configuration). It is shown that, in the deep infrared region, the Gribov copy effects are very significant. Also we show that, in the infinite-volume limit, the zero-momentum value of the propagator does not vanish.

We present the first result for the hyperon vector form factor $f_1$ for ${\Xi }^0\to {\Sigma }^{+}l\overline{\nu }$ and ${\Sigma }^{-}\to nl\overline{\nu }$ semileptonic decays from fully dynamical lattice QCD. The calculations are carried out with gauge configurations generated by the RBC and UKQCD collaborations with ($2+1$)-flavors of dynamical domain-wall fermions and the Iwasaki gauge action at $\beta =2.13$, corresponding to a cutoff $a^{-1}=1.73\mathrm{GeV}$. Our results, which are calculated at the lighter three sea quark masses (the lightest pion mass down to approximately 330 MeV), show that a sign of the second-order correction of SU(3) breaking on the hyperon vector coupling $f_1(0)$ is negative. The tendency of the SU(3)-breaking correction observed in this work disagrees with predictions of both the latest baryon chiral perturbation theory result and large $N_c$ analysis.

The masses of the low-lying strange and charm baryons are evaluated using two degenerate flavors of twisted mass sea quarks for pion masses in the range of about 260 to 450 MeV. The strange and charm valence quark masses are tuned to reproduce the masses of the kaon and $D$ meson at the physical point. The tree-level Symanzik improved gauge action is employed. We use three values of the lattice spacing, corresponding to $\beta =3.9$, $\beta =4.05$ and $\beta =4.2$, with $r_0/a=5.22(2)$, $r_0/a=6.61(3)$ and $r_0/a=8.31(5)$, respectively. We examine the dependence of the strange and charm baryons on the lattice spacing and the strange and charm quark masses. The pion mass dependence is studied and physical results are obtained using heavy-baryon chiral perturbation theory to extrapolate to the physical point.

The successful operation of the LHC provides a great opportunity to study the processes where heavy baryons are involved. In this work we mainly study the weak transitions of ${\Sigma }_b\to {\Sigma }_c$. Assuming the reasonable quark-diquark structure, where the two light quarks constitute an axial vector, we calculate the widths of semileptonic decay ${\Sigma }_b\to {\Sigma }_{c}e{\nu }_e$ and nonleptonic decay modes ${\Sigma }_b\to {\Sigma }_c+M$ (light mesons) in terms of the light-front quark model. We first construct the vertex function for the concerned baryons and then deduce the form factors which are related to two Isgur-Wise functions for the ${\Sigma }_b\to {\Sigma }_c$ transition under the heavy quark limit. Our numerical results indicate that $\Gamma ({\Sigma }_b\to {\Sigma }_{c}e{\nu }_e)$ is about $1.60\pm 0.28\times {10}^{10}{\mathrm{s}}^{-1}$ and $\Gamma ({\Sigma }_b\to {\Sigma }_c+M)$ is slightly below $1\times {10}^{10}{\mathrm{s}}^{-1}$, which may be accessed at the LHCb detector. By the flavor SU(3) symmetry, we estimate the rates of ${\Omega }_b\to {\Omega }_c$. We suggest measuring weak decays of ${\Omega }_b\to {\Omega }_c$, because ${\Omega }_b$ does not decay via strong interactions, creating an obvious advantage.

In this work, we determine the short-distance coefficients for ${\rm Y}$ inclusive decay into a charm pair through relative order $v^4$ within the framework of nonrelativistic QCD (NRQCD) factorization formula. The short-distance coefficient of the order-$v^4$ color-singlet NRQCD matrix element is obtained through matching the decay rate of $b\overline{b}({}^{3}S_1^{[1]})\to c\overline{c}gg$ in full QCD to that in NRQCD. The double and single IR divergences appearing in the decay rate are exactly canceled through the next-to-next-to-leading-order renormalization of the operator $\mathcal{O}({}^{3}S_1^{[8]})$ and the next-to-leading-order renormalization of the operators $\mathcal{O}({}^{3}P_J^{[8]})$. To investigate the convergence of the relativistic expansion arising from the color-singlet contributions, we study the ratios of the order-$v^2$ and -$v^4$ color-singlet short-distance coefficients to the leading-order one. Our results indicate that though the order-$v^4$ color-singlet short-distance coefficient is quite large, the relativistic expansion for the color-singlet contributions in the process ${\rm Y}\to c\overline{c}+X$ converges well due to a small value of $v$. In addition, we extrapolate the value of the mass ratio of the charm quark to the bottom quark, and find the relativistic corrections rise quickly with increase of the mass ratio.

We calculate the wake in charge density and the wake potential due to the passage of a fast parton in an anisotropic quark-gluon plasma. For the sake of simplicity, a small $\xi$ (anisotropic parameter) limit has been considered. When the velocity ($v$) of the jet is parallel to the anisotropy direction ($\widehat{n}$) and remains below the phase velocity ($v_p$), the wake in induced charge density shows a little oscillatory behavior in anisotropic quark-gluon plasma, contrary to the isotropic case. With the jet velocity greater than the phase velocity, the oscillatory behavior increases with $\xi$. Also for $v>v_p$ one observes a clear modification of the conelike structure in the presence of anisotropy. For the parallel direction in the backward region, the depth of the wake potential decreases with the increase of $\xi$ for $v<v_p$, and the potential becomes modified Coulomb-like for higher values of $\xi$. In the forward region, the potential remains modified Coulomb-like with the change in magnitude for nonzero $\xi$, for both $v>v_p$ and $v<v_p$. In the perpendicular direction, the wake potential is symmetric in the forward and backward regions. With the increase of $\xi$, the depth of negative minimum is moving away from the origin irrespective of the jet velocity. On the other hand, when the jet velocity is perpendicular to the anisotropy direction, we find significant changes in the case of both wake charge density and potential in comparison to the isotropic case. For nonzero $\xi$, the oscillatory nature of the color charge wake is reduced at $v>v_p$. Also the oscillatory behavior of the wake potential along the direction of motion of the parton is attenuated in the backward direction for anisotropic plasma at parton velocity $v>v_p$. In the presence of anisotropy, for $v<v_p$, the screening potential along the perpendicular direction of the parton is transformed from the Lennard-Jones type to a modified Coulomb-like potential.

We argue by way of examples that, as a nonlinear integral equation, the gap equation can and does possess many physically distinct solutions for the dressed-quark propagator. The examples are drawn from a class that is successful in describing a broad range of hadron physics observables. We apply the homotopy continuation method to each of our four exemplars and thereby find all solutions that exist within the interesting domains of light current-quark masses and interaction strengths; and simultaneously provide an explanation of the nature and number of the solutions, many of which may be associated with dynamical chiral symmetry breaking. Introducing a stability criterion based on the scalar and pseudoscalar susceptibilities we demonstrate, however, that for any nonzero current-quark mass only the regular Nambu solution of the gap equation is stable against perturbations. This guarantees that the existence of multiple solutions to the gap equation cannot complicate the description of phenomena in hadron physics.

We present a SUSY $SU(5)\times T^{\prime }$ unified flavor model with type I seesaw mechanism of neutrino mass generation, which predicts the reactor neutrino angle to be ${\theta }_{13}\approx 0.14$ close to the recent results from the Daya Bay and RENO experiments. The model predicts also values of the solar and atmospheric neutrino mixing angles, which are compatible with the existing data. The $T^{\prime }$ breaking leads to tribimaximal mixing in the neutrino sector, which is perturbed by sizeable corrections from the charged lepton sector. The model exhibits geometrical $CP$ violation, where all complex phases have their origin from the complex Clebsch-Gordan coefficients of $T^{\prime }$. The values of the Dirac and Majorana $CP$ violating phases are predicted. For the Dirac phase in the standard parametrization of the neutrino mixing matrix we get a value close to 90°: $\delta \cong \pi /2-0.45{\theta }^c\cong 84.3°$, ${\theta }^c$ being the Cabibbo angle. The neutrino mass spectrum can be with normal ordering (2 cases) or inverted ordering. In each case the values of the three light neutrino masses are predicted with relatively small uncertainties, which allows one to get also unambiguous predictions for the neutrinoless double beta decay effective Majorana mass.

We study effects from new colored states and the Higgs portal on gluon fusion production. We isolate possible loop contributions from new colored scalars, fermions, and vectors, incorporating effects from Higgs portal-induced scalar mixing, thus leading to dramatic effects on gluon fusion and branching fractions. Higgs identification must generally allow for these effects, and using our results, possible tensions from fits to the Standard Model expectation can be relieved by inclusion of New Physics effects.