Symmetry Breaking Mass Research Articles

The charge and mass symmetry breaking in the KK K¯ system

In the framework of the Faddeev equations in configuration space, we investigate the K(1460) meson as a resonant state of the KKK¯ kaonic system. We perform calculations for the particle configurations K 0 K + K − and K0K+K0¯ within two models: the ABC model, in which all three particles are distinguishable, and the AAC model when two particles are identical. The models differ in their treatment of the kaon mass difference and the attractive Coulomb force between the K + K − pair. We found that the Coulomb shift adds over 1 MeV to the three-body binding energy. The expected correction to the binding energy due to mass redistribution from AA to AB is found to be negligible, up to a maximum of 6% of the relative mass correction. At the same time, the symmetry of the wave function is distorted depending on the mass ratio value. We found that the repulsive KK interaction plays an essential role in the binding energy of the KKK¯ system and reports the mass of 1461.8 or 1464.1 MeV for the neutral K 0(1460) and 1466.5 or 1468.8 MeV for the charged K +(1460) resonances, respectively, depending on the parameter sets for KK and KK¯ interactions.

Comparison Of Anomalous Higgs Couplings at the Large Hadron Collider and at Proton-Proton Collider with 100 TeV Energy

Gammap and gammagamma ,called photon induced processes, have been examined in various colliders like Large Hadron Collider (LHC) and proton-proton collider with 100 TeV energy. One of the importance of these processes is that they allow for probing the anomalous Higgs couplings. The anomalous Higgs couplings constitute a testing ground for electroweak symmetry breaking (EWSB) mechanism and mass production system. For measuring anomalous Hgammagamma and HZgamma couplings at the LHC and at proton-proton collider with 100 TeV energy, the potential of the pp pgammap pHqX have been examined. Sensitivity bounds on anomalous Higgs couplings have been obtained at %95 confidence level. The analyses have been done for various integrated luminosities and for different scenarios Then the results of them have been compared. Model-independent effective Lagrangian technique have been used and the Higgs boson couplings to gauge bosons have been examined by dimension-six operators.

Vacuum stability and radiative symmetry breaking of the scale-invariant singlet extension of type II seesaw model

The questions of the origin of electroweak symmetry breaking and neutrino mass are two major puzzles in particle physics. Neutrino mass generation requires new physics beyond the Standard Model and also suggests reconsideration of physics of symmetry breaking. The aim of this paper is to study radiative symmetry breaking in the singlet scalar extension of type II seesaw neutrino mass model. We derive bounded-from-below conditions for the scalar potential of the model in full generality for the first time. The Gildener–Weinberg approach is utilised in minimising the multiscalar potential. Upon imposing the bounded-from-below and perturbativity conditions, as well as experimental constraints from colliders, we find the parameter space of scalar quartic couplings that can radiatively realise electroweak symmetry breaking at one-loop level. To satisfy all the constraints, the masses of the heavy triplet-like Higgs bosons must be nearly degenerate. The evolution of the Higgs doublet quartic coupling lambda _{H} can be prevented from being negative up to the Planck scale.

Tailored Topological Edge Waves via Chiral Hierarchical Metamaterials

Precise manipulation of the direction and re-direction of vibrational wave energy is a key demand in wave physics and engineering. We consider the paradigm of a finite frame-like structure and the requirement to channel energy away from critical regions, leaving them vibration-free, and redirect energy along edges towards energy concentrators for damping or energy harvesting. We design an exemplar frame metamaterial, combining two distinct areas of wave physics. Firstly, topological edge states taking an unconventional tetrachiral lattice. We control these highly localised protected edge states leveraging a hierarchy of scales through the addition of micro-resonators that impose tuneable symmetry breaking and reconfigurable mass. This allows us to achieve precise positional control in the macro-scale frame lattice, thereby opening opportunities for robust signal transport and vibration control. Experiments, theory, simulation are all utilised to provide a comprehensive analysis and interpretation of the physics.

Bounds on gauge bosons coupled to nonconserved currents

We discuss new bounds on vectors coupled to currents whose nonconservation is due to mass terms, such as $U(1{)}_{{L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{\ensuremath{\tau}}}$. Due to the emission of many final state longitudinally polarized gauge bosons, inclusive rates grow exponentially fast in energy, leading to constraints that are only logarithmically dependent on the symmetry breaking mass term. This exponential growth is unique to Stueckelberg theories and reverts back to polynomial growth at energies above the mass of the radial mode. We present bounds coming from the high transverse mass tail of $\mathrm{monolepton}+\mathrm{MET}$ events at the LHC, which beat out cosmological bounds to place the strongest limit on Stueckelberg $U(1{)}_{{L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{\ensuremath{\tau}}}$ models for most masses below a keV. We also discuss a stronger, but much more uncertain, bound coming from the validity of perturbation theory at the LHC.

Curvature bound from gravitational catalysis in thermal backgrounds

We investigate the phenomenon of gravitational catalysis, i.e., curvature-induced chiral symmetry breaking and fermion mass generation, at finite temperature. Using a scale-dependent analysis, we derive a thermal bound on the curvature of local patches of spacetime. This bound quantifies regions in parameter space that remain unaffected by gravitational catalysis and thus are compatible with the existence of light fermions as observed in nature. While finite temperature generically relaxes the curvature bound, we observe a comparatively strong dependence of the phenomenon on the details of the curvature. Our bound can be applied to scenarios of quantum gravity, as any realistic candidate has to accommodate a sufficient number of light fermions. We argue that our bound therefore represents a test for quantum-gravity scenarios: A suitably averaged spacetime in the (trans-)Planckian regime that satisfies our curvature bound does not induce correspondingly large Planckian fermion masses by gravitational catalysis. The temperature dependence derived in this work facilitates to follow the fate of gravitational catalysis during the thermal history of the (quantum) Universe. In an application to the asymptotic-safety scenario of quantum gravity, our bound translates into a temperature-dependent upper bound on the number of fermion flavors.

Relativistic freeze-in with scalar dark matter in a gauged B \u2212 L model and electroweak symmetry breaking

We explore relativistic freeze-in production of scalar dark matter in gauged B − L model, where we focus on the production of dark matter from the decay and annihilation of Standard Model (SM) and B − L Higgs bosons. We consider the Bose-Einstein (BE) and Fermi-Dirac (FD) statistics, along with the thermal mass correction of the SM Higgs boson in our analysis. We show that in addition to the SM Higgs boson, the annihilation and decay of the B − L scalar can also contribute substantially to the dark matter relic density. Potential effects of electroweak symmetry breaking (EWSB) and thermal mass correction in BE framework enhance the dark matter relic substantially as it freezes-in near EWSB temperature via scalar annihilation. However, such effects are not so prominent when the dark matter freezes-in at a later epoch than EWSB, dominantly by decay of scalars. The results of this analysis are rather generic, and applicable to other similar scenarios.

Fluctuation and dissipation of axial charge from massive quarks

In quantum chromodynamics (QCD), axial charge is known to be non-conserved due to chiral anomaly and non-vanishing quark mass. In this paper, we explore the role of quark mass in axial charge fluctuation and dissipation. We present two separate calculations of axial charge correlator, which describe dynamics of axial charge. The first is free quarks at finite temperature. We find that axial charge can be generated through effective quantum fluctuations in free theory. However the fluctuation does not follow a random walk behavior. Due to the presence of axial symmetry breaking mass term, the axial charge also does not settle asymptotically to the thermodynamic limit given by susceptibility. The second calculation is in weakly coupled quark gluon plasma (QGP). We find in the hard thermal loop (HTL) approximation, the quark-gluon interaction leads to random walk growth of axial charge, but dissipation is not visible. We estimate relaxation time scale for axial charge, finding it lies beyond the HTL regime.

A Clifford algebra approach to chiral symmetry breaking and fermion mass hierarchies

We propose a Clifford algebra approach to chiral symmetry breaking and fermion mass hierarchies in the context of composite Higgs bosons. Standard model fermions are represented by algebraic spinors of six-dimensional binary Clifford algebra, while ternary Clifford algebra-related flavor projection operators control allowable flavor-mixing interactions. There are three composite electroweak Higgs bosons resulted from top quark, tau neutrino, and tau lepton condensations. Each of the three condensations gives rise to masses of four different fermions. The fermion mass hierarchies within these three groups are determined by four-fermion condensations, which break two global chiral symmetries. The four-fermion condensations induce axion-like pseudo-Nambu–Goldstone bosons and can be dark matter candidates. In addition to the 125 GeV Higgs boson observed at the Large Hadron Collider, we anticipate detection of tau neutrino composite Higgs boson via the charm quark decay channel.

Fractional Hopfions in the Faddeev-Skyrme model with a symmetry breaking potential

We construct new solutions of the Faddeev-Skyrme model with a symmetry breaking potential admitting S1 vacuum. It includes, as a limiting case, the usual SO(3) symmetry breaking mass term, another limit corresponds to the potential m2ϕ12, which gives a mass to the corresponding component of the scalar field. However we find that the spacial distribution of the energy density of these solutions has more complicated structure, than in the case of the usual Hopfions, typically it represents two separate linked tubes with different thicknesses and positions. In order to classify these configurations we define a counterpart of the usual position curve, which represents a collection of loops {mathcal{C}}_1,{mathcal{C}}_{-1} corresponding to the preimages of the points overrightarrow{phi}=left(pm 1,0,0right) , respectively. Then the Hopf invariant can be defined as Q=mathrm{link}left({mathcal{C}}_1,{mathcal{C}}_{-1}right) . In this model, in the sectors of degrees Q = 5,6,7 we found solutions of new type, for which one or both of these tubes represent trefoil knots. Further, some of these solutions possess different types of curves {mathcal{C}}_1 and {mathcal{C}}_{-1} .

Pairing instabilities of Dirac composite fermions

Recently, a Dirac (particle-hole symmetric) description of composite fermions in the half-filled quantum Hall system was proposed [D. T. Son, Phys. Rev. X 5, 031027 (2015)], and we study its possible consequences on BCS (Cooper) pairing of composite fermions (CF's). One of the main consequences is the existence of anisotropic states in single and bilayer systems, which was previously suggested in Ref. [J. S. Jeong and K. Park, Phys. Rev. B 91, 195119 (2015)]. We argue that in the half-filled single layer the gapped states may sustain anisotropy, because isotropic pairings may coexist with anisotropic ones. Furthermore, anisotropic pairings with addition of a particle-hole (PH) symmetry breaking mass term may evolve into rotationally symmetric states, i.e. Pfaffian states of Halperin-Lee-Read (HLR) ordinary CF's. On the basis of the Dirac formalism, we argue that in the quantum Hall bilayer at total filling one, with decreasing distance between layers weak pairing of p-wave paired CF's is gradually transformed from Dirac to ordinary, HLR-like, with concomitant decrease in the CF number. Global characterization of low-energy spectrum based on the Dirac CF's agrees well with previous calculations performed by exact diagonalization on a torus. Finally, we discuss features of Dirac formalism when applied in this context.

From domain wall to overlap in 2 + 1 d

The equivalence of domain wall and overlap fermion formulations is demonstrated for lattice gauge theories in 2+1 spacetime dimensions with parity-invariant mass terms. Even though the domain wall approach distinguishes propagation along a third direction with projectors ${1\over2}(1\pm\gamma_3)$, the truncated overlap operator obtained for finite wall separation $L_s$ is invariant under interchange of $\gamma_3$ and $\gamma_5$. In the limit $L_s\to\infty$ the resulting Ginsparg-Wilson relations recover the expected U($2N_f$) global symmetry up to O($a$) corrections. Finally it is shown that finite-$L_s$ corrections to bilinear condensates associated with dynamical mass generation are characterised by whether even powers of the symmetry-breaking mass are present; such terms are absent for antihermitian bilinears such as $i\bar\psi\gamma_3\psi$, markedly improving the approach to the large-$L_s$ limit.

Strong-coupling phases of 3D Dirac and Weyl semimetals. A renormalization group approach

We investigate the strong-coupling phases that may arise in 3D Dirac and Weyl semimetals under the effect of the long-range Coulomb interaction, considering the many-body theory of these electron systems as a variant of the conventional fully relativistic Quantum Electrodynamics (QED). For this purpose, we apply two different nonperturba-tive approaches, consisting in the sum of ladder diagrams and taking the limit of a large number N of fermion flavors. We benefit from the renormalizability that the theory shows in both cases to compute the anomalous scaling dimensions of different operators exclusively in terms of the renormalized coupling constant, allowing us to determine the precise location of the singularities signaling the onset of the strong-coupling phases. We show then that the QED of 3D Dirac semimetals has two competing effects at strong coupling. One of them is the tendency to chiral symmetry breaking and dynamical mass generation, which are analogous to the same phenomena arising in the conventional QED at strong coupling. This trend is however outweighed by the strong suppression of electron quasiparticles that takes place at large N , leading to a different type of critical point at sufficiently large interaction strength, shared also by the 3D Weyl semimetals. Overall, the phase diagram of the 3D Dirac semimetals turns out to be richer than that of their 2D counterparts, displaying a transition to a phase with non-Fermi liquid behavior which may be observed in materials hosting a sufficiently large number of Dirac or Weyl points.

Ultraviolet complete technicolor and Higgs physics at LHC

We consider a supersymmetric model with a new strong interacting sector. The model is built on a strongly interacting N=4 Super Yang Mills sector, broken explicitly to N=1 supersymmetry by embedding within the Minimal Supersymmetric Standard Model (MSSM). Due to cancellation of global and gauge anomalies, the model additionally features a fourth lepton superfamily. We propose a scenario where all elementary scalars, gauging and higgsinos are decoupled at an energy scale substantially higher than the electroweak (EW) scale, thereby avoiding the little hierarchy problem of MSSM.We construct a low energy effective model, where EW symmetry breaking and viable mass spectrum are produced dynamically. To test further the viability of the model, we work out the Higgs couplings as well as the EW precision parameters and then perform a goodness of fit analysis using LHC and EW precision data. The model fits the given experimental data at a level comparable to that of the Standard Model.

A minimal supersymmetric E6 unified theory

We show explicitly that supersymmetric E 6 Grand Unified Theory with a Higgs sector consisting of $$ \left\{27 + \overline{27} + {351}^{\prime } + {\overline{351}}^{\prime } + 78\right\} $$ fields provides a realistic scenario for symmetry breaking and fermion mass generation. While gauge symmetry breaking can be achieved without the 78 field, its presence is critical for a successful doublet-triplet mass splitting. The Yukawa sector of the model consists of only two symmetric matrices describing all of quark, lepton and neutrino masses and mixings. The fermion mass matrices are computed at low energy and a fit to the second and third generation masses and mixings is performed. We find a good numerical fit to the low-energy data. Thus, this model, having 11 superpotential parameters, alongside the two symmetric Yukawa matrices, seems to be the best realistic candidate for a minimal renormalizable supersymmetric E 6 unified theory.

Predicting the stability of atom-like and molecule-like unit-charge Coulomb three-particle systems.

Non-relativistic quantum chemical calculations of the particle mass, m±2, corresponding to the dissociation threshold in a range of Coulomb three-particle systems of the form m±1m±2m±3, are performed variationally using a series solution method with a Laguerre-based wavefunction. These masses are used to calculate an accurate stability boundary, i.e., the line that separates the stability domain from the instability domains, in a reciprocal mass fraction ternary diagram. This result is compared to a lower bound to the stability domain derived from symmetric systems and reveals the importance of the asymmetric (mass-symmetry breaking) terms in the Hamiltonian at dissociation. A functional fit to the stability boundary data provides a simple analytical expression for calculating the minimum mass of a third particle required for stable binding to a two-particle system, i.e., for predicting the bound state stability of any unit-charge three-particle system.

Hairpin-branes and tachyon-paperclips in holographic backgrounds

D-branes with a U-shaped geometry, like the D8 flavor branes in the Sakai–Sugimoto model of QCD, are encountered frequently in holographic backgrounds. We argue that the commonly used DBI action is inadequate as an effective field theory description of these branes, because it misses a crucial component of the low-energy dynamics: a light complex scalar mode. Following an idea of Erkal, Kutasov and Lunin we elaborate on an effective description based on the abelian tachyon-DBI action which incorporates naturally the non-local physics of the complex scalar mode. We demonstrate its power in a context where an explicit worldsheet description of the open string dynamics exists—hairpin-branes in the background of NS5-branes. Our results are relevant for the holographic description of chiral symmetry breaking and bare quark mass in QCD and open string tachyon condensation in curved backgrounds.

Color neutral two-flavor superconducting phase of cold and dense quark matter in the presence of constant magnetic fields

The color neutral two-flavor superconducting (2SC) phase of cold and dense quark matter is studied in the presence of constant magnetic fields and at moderate baryon densities. In the first part of the paper, a two-flavor effective Nambu--Jona-Lasinio model consisting of a chiral symmetry breaking mass gap sigma_{B}, a color superconducting mass gap Delta_{B} and a color neutrality coefficient mu_{8} is introduced in the presence of a rotated U(1) magnetic field B. To study the phenomenon of magnetic catalysis in the presence of strong magnetic fields, the gap equations corresponding to sigma_{B} and Delta_{B}, as well as mu_{8} are solved in the lowest Landau level approximation. In the second part of the paper, a detailed numerical analysis is performed to explore the effect of any arbitrary magnetic field on the above mass gaps and the color neutrality coefficient. The structure of the chiral symmetry breaking and color superconducting phases is also presented in the mu_{c}-B plane, and the effect of the color neutrality coefficient mu_{8} on the phase structure of the model is explored. As it turns out, whereas the transition from the chiral symmetry breaking to color superconducting phase is of first order, nonvanishing mu_{8} affects essentially the second order phase transition from color superconducting to the normal phase.

SU(3)-symmetry breaking effects and mass splitting in scalar and pseudoscalarDmesons from QCD sum rules

Motivated by the similar mass splitting in light-light and heavy-light meson system in $J^{P}=0^{-}$ and $J^{P}=0^{+}$ channel, taking into account the operator mixing to obtain an infrared stable OPE as well as a complete both non-perturbative and perturbative $\mathcal {O}(m_{q})$ corrections to the correlation function, the SU(3)-symmetry breaking effects in mass splitting in $0^{-}$ and $0^{+}$ channel of $D$ meson are analyzed by QCD sum rule approach based on a $c\bar{q}$ underlying structure. Within the sum rule we get, taking same threshold and Borel window for same channel, we find a correct mass splitting tendency in both channel which agrees with observed spectrum. We find $m_{D_{s}}-m_{D_{d}}\sim35\rm{MeV}$ in $0^{-}$ channel and $m_{D_{d}}-m_{D_{s}}\sim12\rm{MeV}$ in $0^{+}$ channel at scale $\mu=1\rm{GeV}$. These splitting can be accommodated with the different role of combination of mass effects and the parity-dependent "force" induced from non-perturbative QCD vacuum. When we scale up to $\mu=1.3\rm{GeV}$, the splitting remains unchanged which demonstrates a correct scale invariance. Combined with HQET, generalization to other channel of charmed meson and $b$-system are discussed briefly also.

Toward an improved search for neutron–antineutron oscillations

An observation of neutron–antineutron oscillations would constitute a discovery of fundamental importance for particle physics and cosmology. The required change in baryon number and lepton number ( Δ B = 2 , Δ L = 0 ) relates neutron–antineutron oscillations to neutrinoless double beta decay ( Δ B = 0 , Δ L = 2 ) and the physics of B – L symmetry breaking and neutrino mass generation in several theories beyond the Standard Model which unify quarks and leptons. Recent theoretical models which posit new energy scales for B–L symmetry breaking in the ranges from 10 5 to 10 11 GeV can produce neutron–antineutron oscillations close to the existing limits. We mention recent developments in cold and ultracold neutron technology which can make possible improvements in the sensitivity to the free neutron oscillation probability by factors from ≈ 100 to 1000 . For these sensitivities a null result would place the most stringent limit on this possible mode of matter instability.