Bosonic Sector Research Articles

Ternary Z2 × Z3 Graded Algebras and Ternary Dirac Equation

The wave equation generalizing the Dirac operator to the Z3-graded case is introduced, whose diagonalization leads to a sixth-order equation. It intertwines not only quark and anti-quark state as well as the "u" and "d" quarks, but also the three colors, and is therefore invariant under the product group Z2 x Z2 x Z3. The solutions of this equation cannot propagate because their exponents always contain non-oscillating real damping factor. We show how certain cubic products can propagate nevertheless. The model suggests the origin of the color SU(3) symmetry and of the SU(2) x U(1) that arise automatically in this model, leading to the full bosonic gauge sector of the Standard Model.

Perturbation of pulsating strings

We discuss semiclassical quantization of circular pulsating strings in text {AdS}_3 times text {S}^3 background with and without the Neveu-Schwarz–Neveu-Schwarz (NS–NS) flux. We find the equations of motion corresponding to the quadratic action in bosonic sector in terms of scalar quantities and invariants of the geometry. The general equations for studying physical perturbations along the string in an arbitrary curved spacetime are written down using covariant formalism. We discuss the stability of these string configurations by studying the solutions of the linearized perturbed equations of motion.

Gauged six-dimensional supergravity from warped IIB reductions

We find a family of complete non-linear Kaluza-Klein reduction ansätze from type IIB supergravity to Romans’ 6D F (4) gauged supergravity in the bosonic sector. The reduction is over a sphere S2 and a Riemann surface Σ, and depends on a pair of arbitrary locally holomorphic functions {mathcal{A}}_{pm } on Σ. This family of reductions is inspired by the recent construction of 1/2 BPS supersymmetric warped AdS6 solutions of IIB supergravity that depend on these same functions {mathcal{A}}_{pm } .

Leading low-energy effective action in 6D, mathcal{N}=left(1,1right) SYM theory

We elaborate on the low-energy effective action of 6D, mathcal{N}=left(1,1right) supersymmetric Yang-Mills (SYM) theory in the mathcal{N}=left(1,0right) harmonic superspace formulation. The theory is described in terms of analytic mathcal{N}=left(1,0right) gauge superfield V++ and analytic ω-hypermultiplet, both in the adjoint representation of gauge group. The effective action is defined in the framework of the background superfield method ensuring the manifest gauge invariance along with manifest mathcal{N}=left(1,0right) supersymmetry. We calculate leading contribution to the one-loop effective action using the on-shell background superfields corresponding to the option when gauge group SU(N) is broken to SU(N − 1) × ϒ(1) ⊂ SU(N). In the bosonic sector the effective action involves the structure sim frac{F^2}{X^2} , where F4 is a monomial of the fourth degree in an abelian field strength FM N and X stands for the scalar fields from the ω-hypermultiplet. It is manifestly demonstrated that the expectation values of the hypermultiplet scalar fields play the role of a natural infrared cutoff.

Higgs Boson Measurements in CMS with Run II Data

Latest results from the CMS experiment on studies of Higgs boson production are presented. Studies involving the 125 GeV Higgs boson using various Standard Model production and decay modes have been performed using proton proton collisions from data accumulated during the LHC Run II with center-of-mass energy of 13 TeV. Similar datasets have also been used to place constraints on physics beyond the Standard Model involving extended Higgs boson sectors.

Dark matter as ultralight axion-like particle in E6 × U(1)X GUT with QCD axion

Axion-like fields are naturally generated by a mechanism of anomaly cancellation of one or more anomalous gauge abelian symmetries at the Planck scale, emerging as duals of a two-form from the massless bosonic sector of string theory. This suggests an analogy of the Green–Schwarz mechanism of anomaly cancellation, at field theory level, which results in one or more Stueckelberg pseudoscalars. In the case of a single Stueckelberg pseudoscalar b, vacuum misalignments at phase transitions in the early Universe at the GUT scale provide a small mass – due to instanton suppression of the periodic potential – for a component of b, denoted as χ and termed the “axi-Higgs”, which is a physical axion-like particle. The coupling of the axi-Higgs to the gauge sector via Wess–Zumino terms is suppressed by the Planck mass, which guarantees its decoupling, while its angle of misalignment is related to MGUT. We build a gauged E6×U(1) model with anomalous U(1). It contains both an automatic invisible QCD axion and an ultra-light axi-Higgs. The invisible axion present in the model solves the strong CP problem and has mass in the conventional range while the axi-Higgs, which can act as dark matter, is sufficiently light (10−22 eV<mχ<10−20 eV) to solve short-distance problems which confront other cold dark matter candidates.

On pp wave limit for \u03b7 deformed superstrings

In this paper, based on the notion of plane wave string/gauge theory duality, we explore the pp wave limit associated with the bosonic sector of η deformed superstrings propagating in (AdS5 × S5)η . Our analysis reveals that in the presence of NS-NS and RR fluxes, the pp wave limit associated to full ABF background satisfies type IIB equations in its standard form. However, the beta functions as well as the string Hamiltonian start receiving non trivial curvature corrections as one starts probing beyond pp wave limit which thereby takes solutions away from the standard type IIB form. Furthermore, using uniform gauge, we also explore the BMN dynamics associated with short strings and compute the corresponding Hamiltonian density. Finally, we explore the Penrose limit associated with the HT background and compute the corresponding stringy spectrum for the bosonic sector.

Majorana neutrinos in the seesaw mechanism and Bogoliubov quasiparticles

The idea that the Majorana neutrino should be identified as a Bogoliubov quasiparticle is applied to the seesaw mechanism for the three generations of neutrinos in the Standard Model. A relativistic analogue of the Bogoliubov transformation in the present context is a CP-preserving canonical transformation but modifies charge conjugation properties in such a way that the C-noninvariant fermion number violating term (condensate) is converted to a Dirac mass term. Puzzling aspects associated with the charge conjugation of chiral Weyl fermions are clarified. By invoking the Coleman--Weinberg mechanism in the framework of dimensional regularization, it is also noted that seesaw models become unnatural in some parameter regions which induce the hierarchy problems in the bosonic sector.

Supersymmetry and fermionic modes in an oscillon background

The excitations referred to as oscillons are long-lived time-dependent field configurations which emerge dynamically from non-linear field theories. Such long-lived solutions are of interest in applications that include systems of Condensed Matter Physics, the Standard Model of Particle Physics, Lorentz-symmetry violating scenarios and Cosmology. In this work, we show how oscillons may be accommodated in a supersymmetric scenario. We adopt as our framework simple (N=1) supersymmetry in D=1+1 dimensions. We focus on the bosonic sector with oscillon configurations and their (classical) effects on the corresponding fermionic modes, (supersymmetric) partners of the oscillons. The particular model we adopt to pursue our investigation displays cubic superfield which, in the physical scalar sector, corresponds to the usual quartic self-coupling.

From R2 gravity to no-scale supergravity

We show that $R^2$ gravity coupled conformally to scalar fields is equivalent to the real bosonic sector of SU(N,1)/SU(N)$\times$U(1) no-scale supergravity, where the conformal factor can be identified with the K\"ahler potential, and we review the construction of Starobinsky-like models of inflation within this framework.

Section sigma models coupled to symplectic duality bundles on Lorentzian four-manifolds

We give the global mathematical formulation of a class of generalized four-dimensional theories of gravity coupled to scalar matter and to Abelian gauge fields. In such theories, the scalar fields are described by a section of a surjective pseudo-Riemannian submersion π over space–time, whose total space carries a Lorentzian metric making the fibers into totally-geodesic connected Riemannian submanifolds. In particular, π is a fiber bundle endowed with a complete Ehresmann connection whose transport acts through isometries between the fibers. In turn, the Abelian gauge fields are “twisted” by a flat symplectic vector bundle defined over the total space of π. This vector bundle is endowed with a vertical taming which locally encodes the gauge couplings and theta angles of the theory and gives rise to the notion of twisted self-duality, of crucial importance to construct the theory. When the Ehresmann connection of π is integrable, we show that our theories are locally equivalent to ordinary Einstein-Scalar-Maxwell theories and hence provide a global non-trivial extension of the universal bosonic sector of four-dimensional supergravity. In this case, we show using a special trivializing atlas of π that global solutions of such models can be interpreted as classical “locally-geometric” U-folds. In the non-integrable case, our theories differ locally from ordinary Einstein-Scalar-Maxwell theories and may provide a geometric description of classical U-folds which are “locally non-geometric”.

Non-Abelian strings in N = 1 supersymmetric QCD

Non-Abelian flux tubes (strings) are well studied in N = 2 supersymmetric QCD in (3+1) dimensions. In addition to translational zero modes they have also orientational moduli associated with rotations of their fluxes inside a non- Abelian group. The dynamics of the orientational moduli is described by the two dimensional CP(N - 1) model living on the world sheet of the non-Abelian string. In this paper we consider a deformation of N = 2 supersymmetric QCD with the U(N) gauge group and Nf = N quark flavors with a mass term μ of the adjoint matter. In the limit of large μ the theory flows to an N = 1 supersymmetric QCD. We study the solution for the non-Abelian string in this limit and derive an effective theory on the string world sheet. The bosonic sector of this theory is still given by the CP(N -1) model. We study also the fermionic sector of the world sheet theory. Upon the deformation the non-Abelian string is no longer BPS and we show that the fermionic superorientational zero modes are all lifted. This leaves us with the pure bosonic CP(N-1) model on the string world sheet in the limit of N = 1 QCD. We discuss what happens to confined monopoles at large μ.

Signatures of photon-scalar interaction in astrophysical situations

Dimension-5 photon (γ) scalar (ϕ) interaction term usually appear in the Lagrangians of bosonic sector of unified theories of electromagnetism and gravity. This interaction makes the medium dichoric and induces optical activity. Considering a toy model of an ultra-cold magnetized compact star (white dwarf (WD) or neutron star (NS)), we have modeled the propagation of very low energy photons with such interaction, in the environment of these stars. Assuming synchro-curvature process as the dominant mechanism of emission in such environments, we have tried to understand the polarimetric implications of photon-scalar coupling on the produced spectrum of the same. Further more assuming the ‘emission-energy vs emission-altitude’ relation, that is believed to hold in such (i.e., cold magnetized WD or NS) environments, we have tried to point out the possible modifications to the radiation spectrum when the same is incorporated along with dimension-5 photon-scalar mixing operator.

Non-uniqueness of the supersymmetric extension of the O(3) \u03c3-model

We study the supersymmetric extensions of the O(3) σ-model in 1+1 and 2+1 dimensions. We show that it is possible to construct non-equivalent supersymmetric versions of a given model sharing the same bosonic sector and free from higher-derivative terms.

Constrained superfields from inflation to reheating

We construct effective supergravity theories from customized constrained superfields which provide a setup consistent both for the description of inflation and the subsequent reheating processes. These theories contain the minimum degrees of freedom in the bosonic sector required for single-field inflation.

Bilepton signatures at the LHC

We discuss the main signatures of the Bilepton Model at the Large Hadron Collider, focusing on its gauge boson sector. The model is characterised by five additional gauge bosons, four charged and one neutral, beyond those of the Standard Model, plus three exotic quarks. The latter turn into ordinary quarks with the emission of bilepton doublets (Y++,Y+) and (Y−−,Y−) of lepton number L=−2 and L=+2 respectively, with the doubly-charged bileptons decaying into same-sign lepton pairs. We perform a phenomenological analysis investigating processes with two doubly-charged bileptons and two jets at the LHC and find that, setting suitable cuts on pseudorapidities and transverse momenta of final-states jets and leptons, the model yields a visible signal and the main Standard Model backgrounds can be suppressed. Compared to previous studies, our investigation is based on a full Monte Carlo implementation of the model and accounts for parton showers, hadronization and an actual jet-clustering algorithm for both signal and Standard Model background, thus providing an optimal framework for an actual experimental search.

Bosonic D = 11 supergravity from a generalized Chern–Simons action

It is shown that the action of the bosonic sector of D=11 supergravity may be obtained by means of a suitable scaling of the originally dimensionless fields of a generalized Chern–Simons action. This follows from the eleven-form CS-potential of the most general linear combination of closed, gauge invariant twelve-forms involving the sp(32)-valued two-form curvatures supplemented by a three-form field. In this construction, the role of the skewsymmetric four-index auxiliary function needed for the first order formulation of D=11 supergravity is played by the gauge field associated with the five Lorentz indices generator of the bosonic sp(32) subalgebra of osp(1|32).

Twin supergravities from Yang-Mills theory squared

We consider `twin supergravities' - pairs of supergravities with $\mathcal{N}_+$ and $\mathcal{N}_-$ supersymmetries, $\mathcal{N}_+>\mathcal{N}_-$, with identical bosonic sectors - in the context of tensoring super Yang-Mills multiplets. It is demonstrated that the pairs of twin supergravity theories are related through their left and right super Yang-Mills factors. This procedure generates new theories from old. In particular, the matter coupled $\mathcal{N}_-$ twins in $D=3,5,6$ and the $\mathcal{N}_-=1$ twins in $D=4$ have not, as far as we are aware, been obtained previously using the double-copy construction, adding to the growing list of double-copy constructible theories. The use of fundamental matter multiplets in the double-copy construction leads us to introduce a bi-fundamental scalar that couples to the well-known bi-adjoint scalar field. It is also shown that certain matter coupled supergravities admit more than one factorisation into left and right super Yang-Mills-matter theories.

Non-Abelian strings in N=1 supersymmetric QCD

Non-Abelian flux tubes (strings) are well studied in N=2 supersymmetric QCD in (3+1) dimensions. In addition to translational zero modes they have also orientational moduli associated with rotations of their fluxes inside a non-Abelian group. The dynamics of the orientational moduli is described by the two dimensional CP(N-1) model living on the world sheet of the non-Abelian string. In this paper we consider a deformation of N=2 supersymmetric QCD with the U(N) gauge group and N_f=N quark flavors with a mass term $\mu$ of the adjoint matter. In the limit of large $\mu$ the theory flows to an N=1 supersymmetric QCD. We study the solution for the non-Abelian string in this limit and derive an effective theory on the string world sheet. The bosonic sector of this theory is still given by the CP(N-1) model but its scale is exponentially small as compared to the scale of the four dimensional bulk theory in contrast to the N=2 case where these scales are equal. We study also the fermionic sector of the world sheet theory. Upon the deformation the non-Abelian string is no longer BPS and we show that the fermionic superorientational zero modes are all lifted. This leaves us with the pure bosonic CP(N-1) model on the string world sheet in the limit of N=1 QCD. We also discuss what happens to confined monopoles at large $\mu$.

Simulations of Cold Electroweak Baryogenesis: hypercharge U(1) and the creation of helical magnetic fields

We perform numerical simulations of Cold Electroweak Baryogenesis, including for the first time in the Bosonic sector the full electroweak gauge group SU(2) × U(1) and CP-violation. We find that the maximum generated baryon asymmetry is reduced by a factor of three relative to the SU(2)-only model of [1], but that the quench time dependence is very similar. In addition, we compute the magnitude of the helical magnetic fields, and find that it is proportional to the strength of CP-violation and dependent on quench time, but is not proportional to the magnitude of the baryon asymmetry as proposed in [2, 3]. Astrophysical signatures of primordial magnetic helicity can therefore not in general be used as evidence that electroweak baryogenesis has taken place.