Narrow Results

We review the possibility that the Supersymmetric Standard Model arises from orbifold constructions of the E₈×E₈ Heterotic Superstring, and the phenomenological properties that such a model should have. In particular, trying to solve the discrepancy between the unification scale predicted by the Heterotic Superstring (≈g_GUT × 5.27 × 10¹⁷GeV) and the value deduced from LEP experiments (≈2 × 10¹⁶GeV), we will predict the presence at low energies of three families of Higgses and vector-like colour triplets. Our approach relies on the Fayet–Iliopoulos breaking, and this is also a crucial ingredient, together with having three Higgs families, to obtain in these models an interesting pattern of fermion masses and mixing angles at the renormalizable level. Namely, after the gauge breaking some physical particles appear combined with other states, and the Yukawa couplings are modified in a well-controlled way. On the other hand, dangerous flavour-changing neutral currents may appear when fermions of a given charge receive their mass through couplings with several Higgs doublets. We will address this potential problem, finding that viable scenarios can be obtained for a reasonable light Higgs spectrum.

The oscillation neutrino problem in the extended standard model with minimal number of parameters is considered. The dispersion relations with explicit neutrino–antineutrino asymmetry are discussed and an explanation to the MINIBooNE and solar neutrino controversy is offered. Bounds for the CPT violation symmetry are also found.

We discuss the shape of the interaction region of the elastically scattered protons stipulated by the high-energy Pomeron exchange which turns out to be very similar with the shape of the static string representing the confining QCD flux tube. This similarity disappears when we enter the LHC energy region, which corresponds to many-Pomeron exchanges. Reversing the argument we conjecture a modified relationship between the width and the length of the confining string at very large lengths.

Gauge-invariant perturbation theory is an extension of ordinary perturbation theory which describes strictly gauge-invariant states in theories with a Brout–Englert–Higgs effect. Such gauge-invariant states are composite operators which have necessarily only global quantum numbers. As a consequence, flavor is exchanged for custodial quantum numbers in the Standard Model, recreating the fermion spectrum in the process. Here, we study the implications of such a description, possibly also for the generation structure of the Standard Model.

In particular, this implies that scattering processes are essentially bound-state–bound-state interactions, and require a suitable description. We analyze the implications for the pair-production process $e^{+}{e}^{-}\to \bar{f}f$ at a linear collider to leading order. We show how ordinary perturbation theory is recovered as the leading contribution. Using a PDF-type language, we also assess the impact of sub-leading contributions. To lowest order, we find that the result is mainly influenced by how large the contribution of the Higgs at large $x$ is. This gives an interesting, possibly experimentally testable, scenario for the formal field theory underlying the electroweak sector of the Standard Model.

We propose a framework to construct “Domain-Wall Standard Model” in a non-compact 5-dimensional spacetime, where all the Standard Model (SM) fields are localized in certain domains of the 5th dimension and the SM is realized as a 4-dimensional effective theory without any compactification for the 5th dimension. In this context, we investigate the collider phenomenology of the Kaluza–Klein (KK) modes of the SM gauge bosons and the current constraints from the search for a new gauge boson resonance at the Large Hadron Collider Run-2. The couplings of the SM fermions with the KK-mode gauge bosons depend on the configuration of the SM fermions in the 5-dimensional bulk. This “geometry” of the model can be tested at the future Large Hadron Collider experiment, once a KK-mode of the SM gauge boson is discovered.

We have investigated the phenomenological implications of texture one-zero neutrino mass matrix under the lamp post of the latest data on neutrino mass and mixings. In particular, we have obtained the predictions of the model for, yet unknown observables like neutrino mass hierarchy, ${𝜃}_{23}$-octant and CP violation. Out of the six texture one-zero neutrino mass models, $T_1$, $T_2$ and $T_3$ are found to be necessarily CP violating. ${𝜃}_{23}$ can be above or below maximality except for the texture $T_4$ (with NH), wherein ${𝜃}_{23}<45^{\circ }$ at $2.5\sigma$. Also, we have proposed a flavor model based on the non-Abelian group $A_4$ within the paradigm of type-I+II seesaw framework, wherein such textures can be realized.

A machine learning method is applied to analyze lepton mass matrices numerically. The matrices were obtained within a framework of high-scale supersymmetry (SUSY) and a flavor symmetry, which are too complicated to be solved analytically. In this numerical calculation, the heuristic method in machine learning is adopted. Neutrino masses, mixings, and CP violation are obtained. It is found that neutrinos are normally ordered and the favorable effective Majorana mass is about $7\times 10^{-3}\mathrm{\text{eV}}$.

In the framework of anomaly free $U{(1)}_{L_{\mu }-L_{\tau }}$ model, singlet scalar field with nonzero $L_{\mu }-L_{\tau }$ charge gives rise to massive gauge boson $(Z_{\mu \tau })$ through spontaneous symmetry breaking. $Z_{\mu \tau }$ leads to one loop contribution to the muon anomalous magnetic moment. These scalar fields may, also, appear in the structure of right-handed neutrino mass matrix, thus, connecting the possible explanation of muon $(g-2)$ and low-energy neutrino phenomenology through vevs associated with the scalar fields. In this work, we consider textures of inverse neutrino mass matrix $(M_{\nu }^{-1})$ wherein any two elements of the mass matrix are zero. In this ansatz, with Dirac neutrino mass matrix diagonal, the zero(s) of right-handed Majorana neutrino mass matrix correspond to zero(s) in the low-energy effective neutrino mass matrix (within Type-I seesaw). We have realized two such textures of $M_{\nu }^{-1}$ accommodating the muon $(g-2)$ and low-energy neutrino phenomenology. The requirement of successful explanation of muon $(g-2)$, further, constrains the allowed parameter space of the model and results in sharp correlations amongst neutrino mixing angles and CP invariants. The model explains muon $(g-2)$ for $M_{Z_{\mu \tau }}$ in the range (0.035–0.100 GeV) and $g_{\mu \tau }\approx {𝒪}(10^{-4})$ which is found to be consistent with constraints coming from the current experiments CCFR, COHERENT, BABAR while being within sensitivities of future experiments such as NA62 and NA64.

We study the production and signatures of heavy exotic quarks pairs at LHC in the framework of the vector singlet model (VSM), vector doublet model (VDM) and fermion-mirror-fermion (FMF) model. The pair production cross-sections for the electroweak and strong sector are computed.

We present a pedagogical review of particle physics models that are based on the noncommutativity of space–time, , with specific attention to the phenomenology these models predict in particle experiments either in existence or under development. We summarize results obtained for high energy scattering such as would occur, for example, in a future e⁺e^- linear collider with , as well as low energy experiments such as those pertaining to elementary electric dipole moments and other CP violating observables, and finally comment on the status of phenomenological work in cosmology and extra dimensions.

It is evident that models of the knee should match the observational phenomenology. In this talk I discuss a few aspects of phenomenology, which are important not only for the understanding of the knee origin, but also for the general problem of the origin of cosmic rays. Among them are the shape of the energy spectrum, its irregularity, the sharpness of the knee and its fine structure. The classification of models is given and some examples of the most recent models are discussed. The most probable conclusion deduced from this examination is that the knee has an astrophysical origin and the so called 'source' models of the knee are most likely among them.

We review some basic flux vacua counting techniques and results, focusing on the distributions of properties over different regions of the landscape of string vacua and assessing the phenomenological implications. The topics we discuss include: an overview of how moduli are stabilized and how vacua are counted; the applicability of effective field theory; the uses of and differences between probabilistic and statistical analysis (and the relation to the anthropic principle); the distribution of various parameters on the landscape, including cosmological constant, gauge group rank, and supersymmetry-breaking scale; "friendly landscapes;" open string moduli; the (in)finiteness of the number of phenomenologically viable vacua; etc. At all points, we attempt to connect this study to the phenomenology of vacua which are experimentally viable.

We use the phenomenological approach to study properties of space–time in the vicinity of the Schwarzschild black-hole singularity. Requiring finiteness of the Schwarzschild-like metrics we come to the notion of integrable singularity that is, in a sense, weaker than the conventional singularity and allows the (effective) matter to pass to the white-hole region. This leads to a possibility of generating a new universe there. Thanks to the gravitational field of the singularity, this universe is already born highly inflated ("singularity-induced inflation") before the ordinary inflation starts.

Holographic models for the pure gauge quantum chromodynamics (QCD) vacuum are explored. The holographic renormalization of these models is considered as required by a phenomenological approach that takes the β-functions of the models as the only input. This approach is done taking the dilaton as the coordinate orthogonal to the border. This choice greatly simplifies the analysis and gives a geometrical interpretation for the fixed points of the renormalization group flow. Examples are constructed that present asymptotic freedom, confinement of static quarks, either with vanishing or nonvanishing gluon condensate G₂. The latter models require an extension of the dilaton-gravity models already considered in the literature. This extension is also determined by the only input, i.e. the β-function. In addition, the restrictions imposed by the trace anomaly equation (TAE) are studied. In doing so, a holographic derivation of this equation is presented.

Charm and bottom particles are rare in Extensive Air Showers, but their effects can be radical on the EASs development. If such particles show up with a large fraction of primary energy, they can reach large atmospheric depths, depositing energy in deeper layers of the atmosphere. That will cause changes at the EAS observables ($X_{max}$, RMS and $N_{max}$), besides a considerable change in the shape of longitudinal profile energy deposit in the atmosphere. We are using for this work a modified code of an EAS simulator, CORSIKA, with production of charm and bottom particles at the first interaction of the primary cosmic ray. We will show in this paper some results to different $x_F$ values and different production models.

In this paper we present a phenomenological analysis of the Partially Aligned Two Higgs Doublet Model (PA-2HDM) by using leptonic decays of mesons and $B_{d,s}^0$–${\bar{B}}_{d,s}^0$ mixing. We focus our attention in a scenario where the leading contribution to FCNC is given by the tree-level interaction with the light pseudoscalar $A^0$ ($M_{A^0}\sim 250$ GeV). We show how an underlying flavor symmetry controls FCNC in the quark and lepton couplings with the pseudoscalar, without alignment between Yukawa matrices. Upper bounds on the free parameters are calculated in the context of the leptonic decays $B_{s,d}^0\to {\mu }^{+}{\mu }^{-}$ and $K_L^0\to {\mu }^{+}{\mu }^{-}$ and $B_{s,d}^0$ mixing. Also, our assumptions imply that bounds on New Physics contribution in the quark sector coming from $B_{s,d}^0$ mixing impose an upper bound on the parameters for the leptonic sector. Finally we give predictions of branching ratios for leptonic decay of mesons with FCNC and LFV.

In a version of the PA-2HDM where only mixing between third and second fermion generations is allowed, we propose a mechanism to generate the second Yukawa matrix through a Unitary V-spin flavor transformation on the mass matrix for quarks and leptons. This flavor structure is constrained to be universal, that is, we use the same parameters to generate Yukawa matrix elements in the quark and leptonic sectors, reducing drastically the number of free parameters of the PA-2HDM.

As a consequence of this restrictive condition, we obtain relations between the Yukawa matrix elements, that we call the Universal Texture Constraint (UTC). We obtained an interval of values for the second Yukawa matrix elements, expressed in terms of the Cheng and Sher ansatz, for $\tau \to \mu {\mu }^{+}{\mu }^{-}$ and $\tau \to \gamma \mu$ coming from the UTC and experimental bounds for light scalar masses. Finally, we find the allowed parameter region when the experimental bounds and values for $B_s\to \mu \mu$ decays, $B_s^0-{\bar{B}}_s^0$ mixing, $\tau \to \mu {\mu }^{+}{\mu }^{-}$ and $\tau \to \gamma \mu$ are considered.

We present updated LHC limits on the minimal universal extra dimensions (MUEDs) model from the Run 2 searches. We scan the parameter space against a number of searches implemented in the public code CheckMATE and derive up-to-date limits on the MUED parameter space from 13TeV searches. The strongest constraints come from a search dedicated to squarks and gluinos with one isolated lepton, jets and missing transverse energy. In the procedure, we take into account initial state radiation and stress its importance in the MUED searches, which is not always appreciated.

Texture matrices are used to mitigate the redundancy inherent in the description of flavor physics via Yukawa couplings by eliminating some entries in order to identify relevant parameters. In this paper, the implications of a 2-zero texture mixing matrix in the parallel case are studied for leptons. Eight possible parametrizations were found and the parameter space was studied for all the scenarios using a chi-squared analysis. Using a model of GUT with $SO(10)$ symmetry, the mass matrices were restricted and a reduction of parameters was possible by adding the previously proposed Universal Texture Constraint for two scenarios. Constrains on the mass of the heaviest neutrino were found and the interval favored by UTC is $m_{{\nu }_3}\le 0.3$eV as well as general properties of the free parameters of the model.

In this paper we argue that phenomenology needs to be supported by explicit mechanisms if one is to have computational models of consciousness. Computational work in this area is reviewed and a set of axioms that help to decompose being conscious into manageable concepts is evoked. This leads to a kernel architecture and a digital implementation which is shown to work in examples of visual illusions that are revealing of how the brain supports phenomenology. This model is used to address the unstable phenomenology related to observation of the ambiguous Necker cube.