Current LHC results indicate a possible enhancement in the production of Higgs bosons in association with top quarks ($t\overline{t}h$) over the Standard Model (SM) expectations, suggesting an increase in the top Yukawa coupling. To explain these results, we study the effect of adding to the SM a small set of vectorlike partners of the top and bottom quarks with masses of order $\sim 1\mathrm{TeV}$. We consider Yukawa coupling matrices with vanishing determinant and show that Higgs production through gluon fusion is not affected by deviations in the top quark Yukawa coupling, and in fact depends only on deviations in the bottom quark Yukawa coupling. We call this scenario the “brane Higgs limit,” as it can emerge naturally in models of warped extra dimensions with all matter fields in the bulk, except the Higgs (although it could also occur in 4D scenarios with vectorlike quarks and special flavor symmetries forcing the vanishing of the Yukawa determinants). We show that the scenario is highly predictive for all Higgs production/decay modes, making it easily falsifiable, maybe even at the LHC Run 2 with higher luminosity.

We propose a new anomaly-free and family nonuniversal $\mathrm{U}(1{)}^{\prime }$ extension of the standard model with the addition of two scalar singlets and a new scalar doublet. The quark sector is extended by adding three exotic quark singlets, while the lepton sector includes two exotic charged lepton singlets, three right-handed neutrinos, and three sterile Majorana leptons to obtain the fermionic mass spectrum of the standard model. The lepton sector also reproduces the elements of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix and the squared-mass differences data from neutrino oscillation experiments. Also, analytical relations of the PMNS matrix are derived via the inverse seesaw mechanism, and numerical predictions of the parameters in both normal and inverse order scheme for the mass of the phenomenological neutrinos are obtained. We employed a simple seesawlike method to obtain analytical mass eigenstates of the $CP$-even $3\times 3$ mass matrix of the scalar sector.

We discuss the effects of the brane-localized mass terms on the fixed points of the toroidal orbifold $T^2/Z_2$ under the presence of background magnetic fluxes, where multiple lowest and higher-level Kaluza–Klein (KK) modes are realized before introducing the localized masses in general. Using linear algebra, we find that, in each KK level, one or more of the degenerate KK modes are almost inevitably perturbed, when single or multiple brane-localized mass terms are introduced. When the typical scale of the compactification is far above the electroweak scale or the TeV scale, we apply this mechanism for uplifting unwanted massless or light modes which are prone to appear in models on magnetized orbifolds.

The Auger Collaboration has observed the number of muons, which is higher than its prediction by existing hadronic interaction models. We explain this excess of muons by using Lorentz invariance violation (LIV) in the photon sector. As an outcome of Lorentz invariance violation, the dispersion relation of the photon gets modified, which we use for the calculation of ${\pi }^0$ decay width. In the Auger data of primary energy $10^{9.8}<E(\mathrm{GeV})<10^{10.2}$, we find that the neutral pion decay width is suppressed in comparison to its standard model (SM) counterpart. As a result, we get a large number of muons explaining the observed muon excess. We consider Planck-suppressed LIV at order $\mathcal{O}(p^2/M_{\mathrm{Pl}}^2)$ for studying the photon sector, which is in agreement with the current bounds and not as tightly constrained as LIV at order $\mathcal{O}(p/M_{\mathrm{Pl}})$.

We study a left right (LR) extension of the Standard Model (SM) where the Dark Matter(DM) candidate is composed of a set of fermionic Majorana triplets. The DM is stabilized by a remnant $Z_2$ symmetry from the breaking of the LR group to the SM. Two simple scenarios where the DM particles plus a certain set of extra fields lead to gauge coupling unification with a low LR scale are explored. The constraints from relic density and predictions for direct detection are discussed for both scenarios. The first scenario with a $SU(2{)}_R$ vectorlike fermion triplet contains a DM candidate which is almost unconstrained by current direct detection experiments. The second scenario, with an additional $SU(2{)}_R$ triplet, opens up a scalar portal leading to direct detection constraints which are similar to collider limits for right gauge bosons. The DM parameter space consistent with phenomenological requirements can also lead to successful gauge coupling unification in a $SO(10)$ setup.

Torsion is a metric-independent component of gravitation, which may provide a more general geometry than the one taking place within general relativity. On the other hand, torsion could lead to interesting phenomenology in both particle physics and cosmology. In the present work it is shown that a torsion field interacting with the SM Higgs doublet and having a negligible coupling to standard model (SM) fermions is protected from decaying by a $Z_2$ symmetry, and therefore becomes a promising dark matter (DM) candidate. This model provides a good motivation for Higgs portal vector DM scenario. We evaluate the DM relic density and explore direct DM detection and collider constraints on this model to understand its consistency with experimental data and establish the most up-to-date limits on its parameter space. We have found in the model when the Higgs boson is only partly responsible for the generation of torsion mass, there is a region of parameter space where torsion contributes 100% to the DM budget of the Universe. Furthermore, we present the first results on the potential of the LHC to probe the parameter space of minimal scenario with Higgs portal vector DM using mono-jet searches and have found that LHC at high luminosity will be sensitive to the substantial part of model parameter space which cannot be probed by other experiments.

Motivated by recently reported anomalies in a decay of an excited state of beryllium by the Atomki Collaboration, we study a radiative seesaw model with gauged $B-L$ symmetry and a $Z_2$ parity. Assuming that the anomalies originate from the decay of the $B-L$ gauge boson followed by the nuclear decay, the mass of the lightest right-handed neutrino or the dark matter candidate can be determined below 10 GeV. We show that for this mass range, the model can explain the anomalies in the beryllium decay and the relic dark matter abundance consistent with neutrino masses. We also predict its spin-independent cross section in direct detection experiments for this mass range.

We discuss a class of models with gauge-mediated supersymmetry-breaking characterized by a nonunified messenger sector inducing nonstandard gaugino mass ratios, as well as by additional contributions to the soft mass terms from a matter-messenger coupling. The well-known effect of this coupling is to generate A-terms at one-loop level, hence raising the Higgs mass without relying on superheavy stops. At the same time, a hierarchy between Wino and gluino masses, as induced by the nonunified messenger fields, can greatly lower the radiative corrections to the Higgs soft mass term driven by the high-energy parameters, thus reducing the fine-tuning. We search for models with low fine-tuning within this scenario, and we discuss the spectrum, collider phenomenology, constraints, and prospects of the found solutions. We find that some setups are accessible or already excluded by searches at the Large Hadron Collider, and all our scenarios with a tuning better than about 2% can be tested at the International Linear Collider.

Here we study the pattern of neutrino oscillations emerging from a previously proposed warped standard model construction incorporating $\mathrm{\Delta }(27)$ flavor symmetry [J. High Energy Phys. 01 (2016) 007]. In addition to a complete description of fermion masses, the model predicts the lepton mixing matrix in terms of two parameters. The good measurement of ${\theta }_{13}$ makes these two parameters tightly correlated, leading to an approximate one-parameter description of neutrino oscillations. We find secondary minima for the $CP$ phase absent in the general unconstrained oscillation scenario and determine the fourfold degenerate sharp correlation between the physical $CP$ phase ${\delta }_{CP}$ and the atmospheric mixing angle ${\theta }_{23}$. This implies that maximal ${\theta }_{23}$ correlates with maximal leptonic $CP$ violation. We perform a realistic estimate of the total neutrino and antineutrino event numbers expected at long baseline oscillation experiments T2K, NOvA, and the upcoming DUNE proposal. We show how an improved knowledge of the $CP$ phase will probe the model in a significant way.

We present physics results from simulations of QCD using $N_f=2$ dynamical Wilson twisted mass fermions at the physical value of the pion mass. These simulations are enabled by the addition of the clover term to the twisted mass quark action. We show evidence that compared to previous simulations without this term, the pion mass splitting due to isospin breaking is almost completely eliminated. Using this new action, we compute the masses and decay constants of pseudoscalar mesons involving the dynamical up and down as well as valence strange and charm quarks at one value of the lattice spacing, $a\approx 0.09\mathrm{fm}$. Further, we determine renormalized quark masses as well as their scale-independent ratios, in excellent agreement with other lattice determinations in the continuum limit. In the baryon sector, we show that the nucleon mass is compatible with its physical value and that the masses of the $\mathrm{\Delta }$ baryons do not show any sign of isospin breaking. Finally, we compute the electron, muon and tau lepton anomalous magnetic moments and show the results to be consistent with extrapolations of older ETMC data to the continuum and physical pion mass limits. We mostly find remarkably good agreement with phenomenology, even though we cannot take the continuum and thermodynamic limits.

We present the first lattice-QCD calculation of the pion distribution amplitude using the large-momentum effective field theory (LaMET) approach, which allows us to extract light cone parton observables from a Euclidean lattice. The mass corrections needed to extract the pion distribution amplitude from this approach are calculated to all orders in $m_{\pi }^2/P_z^2$. We also implement the Wilson-line renormalization which is crucial to remove the power divergences in this approach, and find that it reduces the oscillation at the end points of the distribution amplitude. Our exploratory result at 310-MeV pion mass favors a single-hump form broader than the asymptotic form of the pion distribution amplitude.

We investigate the static interquark potential for the three-quark system in SU(3) lattice gauge theory at zero temperature by using Monte Carlo simulations. We extract the potential from the correlation function of the three Polyakov loops, which are computed by employing the multilevel algorithm. We obtain remarkably clean results of the three-quark potential for $O(200)$ sets of the three-quark geometries including not only the cases that three quarks are put at the vertices of acute, right, and obtuse triangles, but also the extreme cases such that three quarks are put in line. We find several new interesting features of the three-quark potential and then discuss its possible functional form.

In semileptonic $B$ decays with a tau lepton, features of the production process are imprinted on the tau helicity states. Since the tau momentum cannot be fully reconstructed experimentally, the available information on the tau properties is encoded in its visible decay products. Focusing on the process $B\to D\tau \nu$, we find explicit relations between the tau properties and the kinematics of the charged particles in the decays $\tau \to \pi \nu$, $\tau \to \rho \nu$, and $\tau \to \ell \nu \overline{\nu }$. In particular, we show that the perpendicular polarization $P_{\perp }$ and the forward-backward asymmetry $A_{\tau }$ of the tau lepton can simultaneously be extracted from an angular asymmetry of the charged particle against the $D$ meson. For the most sensitive decay channel, $\tau \to \pi \nu$, we expect a relative statistical precision of about 10% for $P_{\perp }$ and $A_{\tau }$ in a measurement based on $50{\mathrm{ab}}^{-1}$ of data at Belle II.

The vector charmoniumlike state $Y(4220)$ was reported recently in the cross sections of $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{h}_c$, $\omega {\chi }_{c0}$, ${\pi }^{+}{\pi }^{-}J/\psi$, and $D^0{D}^{*-}{\pi }^{+}+\mathrm{c}.\mathrm{c}.$ measured by the BESIII experiment. A combined fit is performed to the cross sections of these four final states to measure the resonant parameters of the $Y(4220)$. We determine a mass $M=(4219.6\pm 3.3\pm 5.1)\mathrm{MeV}/c^2$ and a total width $\mathrm{\Gamma }=(56.0\pm 3.6\pm 6.9)\mathrm{MeV}$ for the $Y(4220)$, where the first uncertainties are statistical and the second ones systematic. We determine the lower limit of its leptonic decay width of around 30 eV, which can be compared with the theoretical expectations of different models. We also estimate its partial decay width to $\pi \pi J/\psi$ in different scenarios. This information is essential for the understanding of the nature of this state.

In this note, we extend the striking connections between quantum integrable systems and conformal blocks recently found in [M. Isachenkov and V. Schomerus, Phys. Rev. Lett. 117, 071602 (2016)] in several directions. First, we explicitly demonstrate that the action of the quartic conformal Casimir operator on general d-dimensional scalar conformal blocks can be expressed in terms of certain combinations of commuting integrals of motions of the two particle hyperbolic ${\mathrm{BC}}_2$ Calogero-Sutherland system. The permutation and reflection properties of the underlying Dunkl operators play crucial roles in establishing such a connection. Next, we show that the scalar superconformal blocks in superconformal field theories (SCFTs) with four and eight supercharges and suitable chirality constraints can also be identified with the eigenfunctions of the same Calogero-Sutherland system; this demonstrates the universality of such a connection. Finally, we observe that the so-called “seed” conformal blocks for constructing four point functions for operators with arbitrary space-time spins in four-dimensional CFTs can also be linearly expanded in terms of Calogero-Sutherland eigenfunctions.

We explain how to find the asymptotic form of fixed point solutions in functional truncations, in particular $f(R)$ approximations. We find that quantum fluctuations do not decouple at large $R$, typically leading to elaborate asymptotic solutions containing several free parameters. By a counting argument, these can be used to map out the dimension of the fixed point solution spaces. They are also necessary to validate the numerical solution and provide the physical part in the limit that the cutoff is removed: the fixed point equation of state. As an example, we apply the techniques to a recent $f(R)$ approximation by Demmel et al., finding asymptotic matches to their numerical solution. Depending on the value of the endomorphism parameter, we find many other asymptotic solutions and fixed point solution spaces of differing dimensions, yielding several alternative scenarios for the equation of state. Asymptotic studies of other $f(R)$ approximations are needed to clarify the picture.

The Kibble-Zurek (KZ) mechanism describes the generations of topological defects when a system undergoes a second-order phase transition via quenches. We study the holographic KZ scaling using holographic superconductors. The scaling can be understood analytically from a scaling analysis of the bulk action. The argument is reminiscent of the scaling analysis of the mean-field theory but is more subtle and is not entirely obvious. This is because the scaling is not the one of the original bulk theory but is an emergent one that appears only at the critical point. The analysis is also useful to determine the dynamic critical exponent $z$.

We show, under a very general set of assumptions, that pairs of identical particle detectors in spacelike separation, such as atomic probes, can only harvest entanglement from the vacuum state of a quantum field when they have a nonzero energy gap. Furthermore, we show that degenerate probes are strongly challenged to become entangled through their interaction through scalar and electromagnetic fields even in full light contact. We relate these results to previous literature on remote entanglement generation and entanglement harvesting, giving insight into the energy gap’s protective role against local noise, which prevents the detectors from getting entangled through the interaction with the field.

In a previous paper, we derived the quantum states of a Dirac particle in a circular, intense magnetic field in the limit of low momentum perpendicular to the field with the purpose of giving a quantum description of the trajectory of an electron, or a positron, in a typical pulsar or magnetar magnetosphere. Here we continue this work by computing the radiation resulting from transitions between these states. This leads us to derive from first principles a quantum theory of the so-called curvature and synchro-curvature radiations relevant for rotating neutron star magnetospheres. We find that, within the approximation of an infinitely confined wave function around the magnetic field and in the continuous energy-level limit, classical curvature radiation can be recovered in a fully consistent way. Further we introduce discrete transitions to account for the change of momentum perpendicular to the field and derive expressions for what we call quantum synchro-curvature radiation. Additionally, we express deconfinement and quantum recoil corrections.