Bare Mass Research Articles

Field theory for zero temperature soft anharmonic spin glasses in a field

We introduce a finite dimensional anharmonic soft spin glass in a field and show how it allows the construction a field theory at zero temperature and the corresponding loop expansion. The mean field level of the model coincides with a recently introduced fully connected model, the KHGPS model, and it has a spin glass transition in a field at zero temperature driven by the appearance of pseudogapped non-linear excitations. We analyze the zero temperature limit of the theory and the behavior of the bare masses and couplings on approaching the mean field zero temperature critical point. Focusing on the so called replicon sector of the field theory, we show that the bare mass corresponding to fluctuations in this sector is strictly positive at the transition in a certain region of control parameter space. At the same time the two relevant cubic coupling constants g 1 and g 2 show a non-analytic behavior in their bare values: approaching the critical point at zero temperature, g 1 → ∞ while g 2 ∝ T with a prefactor diverging at the transition. Along the same lines we also develop the field theory to study the density of states of the model in finite dimension. We show that in the mean field limit the density of states converges to the one of the KHGPS model. However the construction allows a treatment of finite dimensional effects in perturbation theory.

Fermi Surface and Mass Renormalization in the Iron-Based Superconductor YFe_{2}Ge_{2}.

Interaction-enhanced carrier masses are central to the phenomenology of iron-based superconductors. Quantum oscillation measurements in the new unconventional superconductor YFe_{2}Ge_{2} resolve all four Fermi surface pockets expected from band structure calculations, which predict an electron pocket in the Brillouin zone corner and three hole pockets enveloping the centers of the top and bottom of the Brillouin zone. Carrier masses reach up to 20 times the bare electron mass and are among the highest ever observed in any iron-based material, accounting for the enhanced heat capacity Sommerfeld coefficient ≃100 mJ/mol K^{2}. Mass renormalization is uniform across reciprocal space, suggesting predominantly local correlations, as in the Hund's metal scenario.

Quantum computation of phase transition in the massive Schwinger model

As pointed out by Coleman, physical quantities in the Schwinger model depend on a parameter θ that determines the background electric field. There is a phase transition for θ = π only. We develop a momentum space formalism on a lattice and use it to perform a quantum computation of the critical point of this phase transition on the NISQ device IMB Q Lima. After error mitigation, our results give strong indication of the existence of a critical point at m/e ≃ 0.32, where m is the bare fermion mass and e is the coupling strength, in good agreement with the classical numerical result m/e ≃ 0.3335.

Mass spectra and strong decays of charmed and charmed-strange mesons

A semi-relativistic potential model is adopted to calculate the mass spectra of charmed and charmed-strange meson states up to the $2D$ excitations.The strong decay properties are further analyzed with a chiral quark model by using the numerical wave functions obtained from the potential model. By using the strong decay amplitudes extracted from the chiral quark model, we also systematically study the coupled-channel effects on the bare masses of the $1P$-wave states, since the masses of $D^*_{s0}(2317)$ and $D_{s1}(2460)$ cannot be explained with bare $1P$-wave states within the potential model. Based on our good descriptions of the mass and decay properties for the low-lying well-established states, we give a quark model classification for the high mass resonances observed in recent years. In the $D$-meson family, $D_0(2550)$ can be classified as the radially excited state $D(2^1S_0)$; $D_3^*(2750)$ and $D_2(2740)$ can be classified as the second orbital excitations $D(1^3D_3)$ and $D(1D'_2)$, respectively; $D_J^*(3000)$ may be a candidate of $D(1^3F_4)$ or $D(2^3P_2)$; while $D_J(3000)$ may favor the high mass mixed state $D(2P'_1)$; however, there still exist puzzles for understanding the natures of $D_1^*(2600)$ and $D_1^*(2760)$, whose decay properties cannot be well explained with either pure $D(2^3S_1)$ and $D(1^3D_1)$ states or their mixing. In the $D_s$-meson family, $D_{s3}^*(2860)$ favors the $D_s(1^3D_3)$ assignment; $D_{s1}^*(2700)$ and $D_{s1}^*(2860)$ may favor the mixed states $|(SD)_1\rangle_L$ and $|(SD)_1\rangle_H$ via the $2^3S_1$-$1^3D_1$ mixing, respectively; $D_{sJ}(3040)$ may favor $D_s(2P_1)$ or $D_s(2P_1')$, or corresponds to a structure contributed by both $D_s(2P_1)$ and $D_s(2P_1')$.

𝒩 = 1 Curves on Generalized Coulomb Branches of Supersymmetric Gauge Theories

We study the low energy effective dynamics of four-dimensional N=1 superconformal theories on their generalized Coulomb branch. The low energy effective gauge couplings are naturally encoded in algebraic curves X, which we derive for general values of the couplings and mass deformations. We then recast these IR curves X to the UV or M-theory form C: the punctured Riemann surfaces on which the M5 branes are compactified giving the four-dimensional theories. We find that the UV curves C and their corresponding meromorphic differentials take the same form as those for their mother four-dimensional N=2 theories of class S. They have the same poles, and their residues are functions of all the exactly marginal couplings and the bare mass parameters which we can compute exactly.

A ½ spin fiber model for the electron

The Standard Model and Quantum Mechanics studies the quantum world as a collection of probabilistically interacting particles and does not tell us what a single isolated particle like the electron is, thus its intrinsic detailed field mechanics and how these are generating its intrinsic property values like charge, spin, magnetic moment and handedness. We herein are translating these intrinsic physical properties of the electron to a novel 4-dimensional (i.e. three spatial plus one temporal) fiber spinor and showing their possible deeper correlation and interconnection combined under a single energy manifold. From physical quantum emulation observations, mathematical analysis and Wolfram Alpha parametric polar simulations and mathematical 4D animations we calculated a fiber model for the dressed bare mass electromagnetic field of the electron that results to all of its known measured intrinsic properties. Therefore our model is an intrinsic mechanics model for the electron at rest and shows the possibility that the elementary electron although it has no inner sub-particles, it can posses a specific energy flux manifold. Why an electron is actually a ½ spin geometry, twisted photon. The fine structure constant is explained as a topological feature, proportionality constant, embedded inside our proposed fiber model for the electron. Our novel fiber model opens up a new door on theoretical intrinsic mechanics physics of elementary particles beyond the Standard Model.Â

Constraining the Generalized Uncertainty Principle with the light twisted by rotating black holes and M87*

We test the validity of the Generalized Heisenberg's Uncertainty principle in the presence of strong gravitational fields nearby rotating black holes; Heisenberg's principle is supposed to require additional correction terms when gravity is taken into account, leading to a more general formulation also known as the Generalized Uncertainty Principle. Using as probes electromagnetic waves acquiring orbital angular momentum when lensed by a rotating black hole, we find from numerical simulations a relationship between the spectrum of the orbital angular momentum of light and the corrections needed to formulate the Generalized Uncertainty Principle, here characterized by the rescaled parameter β0, a function of the Planck's mass and the bare mass of the black hole. Then, from the analysis of the observed twisted light due to the gravitational field of the compact object observed in M87, we find new limits for the parameter β0. With this method, complementary to black hole shadow circularity analyses, we obtain more precise limits from the experimental data of M87*, confirming the validity of scenarios compatible with General Relativity, within the uncertainties due to the experimental errors present in EHT data and those due to the numerical simulations and analysis.

Quantum quenches in an interacting field theory: Full quantum evolution versus semiclassical approximations

We develop a truncated Hamiltonian method to investigate the dynamics of the $(1+1)d~\phi^4$ theory following quantum quenches. The results are compared to two different semi-classical approaches, the self-consistent Gaussian approximation and the truncated Wigner approximation, and used to determine the range of validity of these widely used approaches. We show that the self-consistent approximation is strongly limited in comparison to the truncated Hamiltonian method which for larger cutoffs is practically exact for the parameter range studied. We find that the self-consistent approximation is only valid when the effective mass is in the vicinity of the renormalised mass. Similarly to the self-consistent approximation, the truncated Wigner approximation is not able to capture the correct mass renormalisation, and breaks down for strong enough interactions where the bare mass becomes negative. We attribute the failure of TWA to the presence of a classical symmetry broken fixed point. Besides establishing the truncated Hamiltonian approach as a powerful tool for studying the dynamics of the $\phi^4$ model, our results on the limitation of semi-classical approximations are expected to be relevant for modelling the dynamics of other quantum field theories.

Highly Accurate Relations between the Fine Structure Constant and Particle Masses, with Application to Its Cosmological Measurement

Highly accurate algebraic relations between the fine structure constant a and a wide range of particle masses are given, ranging from Δa/a = (2.1 ± 0.1)×10-7 to Δa/a = (-2.7 ± 0.3 ± 0.6)×10-8, and with a very large standard deviation, ranging to Δa/a = -5.5×10-9. The analysis is based on empirical relations that exist among some particle masses, and also on several theoretical assumptions, of which the most significant is that the electromagnetic contribution to the electron’s mass is finite, and given by f ameb, where f is a dimensionless parameter that is shown to be equal to 1.032409810 (63), and where meb is the electron’s “bare mass.” The relations for a and f are homogeneous degree zero in the particle masses. The relations for f in terms of particle masses are found by trial and error. A quadratic equation is given relating a to f and me/mp. This equation is used in the application to cosmological measurements of a, and , where it is shown that, to a few percent accuracy, δa/a ≈ -δμ/μ. This relation can serve to test the validity of measurements of a and μ.

Seesaw lepton masses and muon $$g-2$$ from heavy vector-like leptons

We propose a model for the vector-like lepton to explain the small muon mass by a seesaw mechanism, based on lepton-specific two Higgs doublet models with a local $U(1)'$ symmetry. There is no bare muon mass for a nonzero $U(1)'$ charge of the leptophilic Higgs doublet, so the physical muon mass is generated due to the mixing between the vector-like lepton and the muon after the leptophilic Higgs doublet and the dark Higgs get VEVs. In this scenario, the non-decoupling effects of the vector-like lepton give rise to leading contributions to the muon $g-2$, thanks to the light $Z'$ and the light dark Higgs boson. We discuss various constraints on the model from lepton flavor violation, electroweak precision and Higgs data, as well as collider searches.

A syntactically-driven approach to indefiniteness, specificity and anti-specificity in Romance

In this paper we present an original approach to analyze the compositionality of indefinite expressions in Romance by investigating the relevance of their syntactic distribution in relation to their meaning. This approach has the advantage of allowing us to explore the question of how syntactic structure can determine the meaning of different forms of indefiniteness. To that end, we postulate a common derivation for bare plurals, bare mass anddephrases, whereby an abstract operatordeis adjoined to definite determiners and shifts entities into property-type expressions. Quantificational specificity is proposed to be derived from a syntactic structure in which weak quantifiers select for indefinitede-phrases, no matter whetherdeis overt at Spell-Out or not; these quantifiers turn properties into generalized quantifiers. The anti-specificity meaning of some indefinites is derived by adjoining in the syntactic structure an abstract operatoralgthat encodes the speaker’s epistemic state of ignorance to a quantifier encoded for specificity, and it turns a generalized quantifier into a modified generalized quantifier. The paper also brings some general predictions on how indefiniteness is expressed in Romance, as it provides extensive support from five Romance languages: Brazilian Portuguese, Catalan, French, Italian and Spanish.

Backreaction of Schwinger pair creation in massive QED2

Particle-antiparticle pairs can be produced by background electric fields via the Schwinger mechanism provided they are unconfined. If, as in QED in (3+1)-d these particles are massive, the particle production rate is exponentially suppressed below a threshold field strength. Above this threshold, the energy for pair creation must come from the electric field itself which ought to eventually relax to the threshold strength. Calculating this relaxation in a self-consistent manner, however, is difficult. Chu and Vachaspati addressed this problem in the context of capacitor discharge in massless QED2 [1] by utilizing bosonization in two-dimensions. When the bare fermions are massless, the dual bosonized theory is free and capacitor discharge can be analyzed exactly [1], however, special care is required in its interpretation given that the theory exhibits confinement. In this paper we reinterpret the findings of [1], where the capacitors Schwinger-discharge via electrically neutral dipolar meson-production, and generalize this to the case where the fermions have bare masses. Crucially, we note that when the initial charge of the capacitor is large compared to the charge of the fermions, Q » e, the classical equation of motion for the bosonized model accurately characterizes the dynamics of discharge. For massless QED2, we find that the discharge is suppressed below a critical plate separation that is commensurate with the length scale associated with the meson dipole moment. For massive QED2, we find in addition, a mass threshold familiar from (3+1)-d, and show the electric field relaxes to a final steady state with a magnitude proportional to the initial charge. We discuss the wider implications of our findings and identify challenges in extending this treatment to higher dimensions.

Domain wall fermions on the brane

We study domain wall fermions and their condensation in the D3/probe D7 system. A spatially dependent mass term for the N=2 hypermultiplet can be arranged to isolate distinct two component fermions on two 2+1 dimensional domain walls. We argue that the system shows condensation/mass generation analogous to the D3/probe D5 anti-D5 system. The chiral condensate and pion mass can be directly computed on the domain wall. We provide evidence that these systems with the domains separated by a width w have a bare (current) quark mass that scales as 1/w when the spatial dependent mass is large. Adding a magnetic field does not induce chiral symmetry breaking between the separated domain wall fermions, but a similar phenomenological dilaton factor can be made strong enough to introduce spontaneous symmetry breaking. We show a Gell-Man-Oakes-Renner relation for the pions in that case and also for the case where the D7 probe is in a back-reacted dilaton flow geometry. The vacuum configurations can also be interpreted as having a spontaneously generated mass by a Nambu-Jona-Lasinio four fermion operator, depending on the choice of boundary conditions on fluctuations, according to Witten's multi-trace prescription.

Quantum-fluctuation-induced superfluid density in two-dimensional spin-orbit-coupled Bose-Einstein condensates

We study a two-dimensional spin-$\frac{1}{2}$ interacting Bose-Einstein condensate with a Rashba-Dresselhaus spin-orbit coupling. The analytical expression of the superfluid density is derived from the linear response theory and Bogoliubov approximation. We find that the superfluid density can be divided into three terms, which originate from the condensate, the interaction between the condensate and the Bogoliubov excitations, and only the excitations. We show that the condensate-excitation interaction changes the bare mass in the superfluid density into the effective mass. In the isotropic spin-orbit coupling limit, the effective mass diverges, and the superfluid density is predicted to be zero within previous studies; however, our work shows that the excitation-induced superfluid density remains nonzero, which means that quantum fluctuations rescue the superfluidity. Our results show the importance of the quantum fluctuations in understanding the superfluid properties of spin-orbit-coupled Bose-Einstein condensates.

Weak second Bianchi identity for static, spherically symmetric spacetimes with timelike singularities

The (twice-contracted) second Bianchi identity is a differential curvature identity that holds on any smooth manifold with a metric. In the case when such a metric is Lorentzian and solves Einstein’s equations with an (in this case inevitably smooth) energy–momentum–stress tensor of a ‘matter field’ as the source of spacetime curvature, this identity implies the physical laws of energy and momentum conservation for the ‘matter field’. The present work inquires into whether such a Bianchi identity can still hold in a weak sense for spacetimes with curvature singularities associated with timelike singularities in the ‘matter field’. Sufficient conditions that establish a distributional version of the twice-contracted second Bianchi identity are found. In our main theorem, a large class of spherically symmetric static Lorentzian metrics with timelike one-dimensional singularities is identified, for which this identity holds. As an important first application we show that the well-known Reissner–Weyl–Nordström spacetime of a point charge does not belong to this class, but that Hoffmann’s spacetime of a point charge with negative bare mass in the Born–Infeld electromagnetic vacuum does.

Interpolating ’t Hooft model between instant and front forms

The 't Hooft model, i.e., the two-dimensional quantum chromodynamics in the limit of infinite number of colors, is interpolated by an angle parameter $\ensuremath{\delta}$ between $\ensuremath{\delta}=0$ for the instant form dynamics (IFD) and $\ensuremath{\delta}=\ensuremath{\pi}/4$ for the light-front dynamics (LFD). With this parameter $\ensuremath{\delta}$, we formulate the interpolating mass gap equation which takes into account the nontrivial vacuum effect on the bare fermion mass to find the dressed fermion mass. Our interpolating mass gap solutions not only reproduce the previous IFD result at $\ensuremath{\delta}=0$ as well as the previous LFD result at $\ensuremath{\delta}=\ensuremath{\pi}/4$ but also link them together between the IFD and LFD results with the $\ensuremath{\delta}$ parameter. We find the interpolation angle independent characteristic energy function which satisfies the energy-momentum dispersion relation of the dressed fermion, identifying the renormalized fermion mass function and the wave function renormalization factor. The renormalized fermion condensate is also found independent of $\ensuremath{\delta}$, indicating the persistence of the nontrivial vacuum structure even in the LFD. Using the dressed fermion propagator interpolating between IFD and LFD, we derive the corresponding quark-antiquark bound-state equation in the interpolating formulation verifying its agreement with the previous bound-state equations in the IFD and LFD at $\ensuremath{\delta}=0$ and $\ensuremath{\delta}=\ensuremath{\pi}/4$, respectively. The mass spectra of mesons bearing the feature of the Regge trajectories are found independent of the $\ensuremath{\delta}$-parameter reproducing the previous results in LFD and IFD for the equal mass quark and antiquark bound states. The Gell-Mann-Oakes-Renner relation for the pionic ground-state in the zero fermion mass limit is confirmed indicating that the spontaneous breaking of the chiral symmetry occurs in the 't Hooft model regardless of the quantization for $0\ensuremath{\le}\ensuremath{\delta}\ensuremath{\le}\ensuremath{\pi}/4$. We obtain the corresponding bound-state wave functions and discuss their reference frame dependence with respect to the frame independent LFD result. Applying them for the computation of the so-called quasi-parton distribution functions now in the interpolating formulation between IFD and LFD, we note a possibility of utilizing not only the reference frame dependence but also the interpolation angle dependence to get an alternative effective approach to the LFD-like results.

The effects of charmonium on the properties of the 1++ hidden charm poles in effective field theory

In this study, the properties of the JPC=1++ hidden charm poles are analyzed under the variation of the bare 2P charmonium mass within the effective field theory proposed in Ref. [1]. The main focus of the current work is on the pole trajectory of the χc1(2P) charmonium dressed by the DD¯⁎ meson loops. It is shown that the trajectories of the pole change radically for values of the bare charmonium mass above a certain value and also depending on how close the pole is to the threshold.

Nonperturbative Infrared Finiteness in a Superrenormalizable Scalar Quantum Field Theory.

We present a study of the IR behavior of a three-dimensional superrenormalizable quantum field theory consisting of a scalar field in the adjoint of SU(N) with a φ^{4} interaction. A bare mass is required for the theory to be massless at the quantum level. In perturbation theory, the critical mass is ambiguous due to IR divergences, and we indeed find that at two loops in lattice perturbation theory the critical mass diverges logarithmically. It was conjectured long ago in [R. Jackiw et al., Phys. Rev. D 23, 2291 (1981)PRVDAQ0556-282110.1103/PhysRevD.23.2291, T. Appelquist et al., Phys. Rev. D 23, 2305 (1981)PRVDAQ0556-282110.1103/PhysRevD.23.2305] that superrenormalizable theories are nonperturbatively IR finite, with the coupling constant playing the role of an IR regulator. Using a combination of Markov Chain MonteCarlo simulations of the lattice-regularized theory, frequentist and Bayesian data analysis, and considerations of a corresponding effective theory, we gather evidence that this is indeed the case.

Tunable thermal conductivity of ternary alloy semiconductors from first-principles

We compute the thermal conductivity, κ, of five representative III–V ternary alloys—namely In x Ga1 − x As, GaAs1 − x P x , InAs1 − x Sb x , GaAs1 − x N x , and GaP1 − x N x —in the whole range of compositions, and in zincblende and wurtzite crystal phases, using a first-principles approach and solving the phonon Boltzmann transport equation beyond the relaxation time approximation. We discuss the tunability of the thermal conductivity with the composition of the alloy, reporting a steep decrease in the thermal conductivity, followed by a wide plateau and a steep increase common in systems with lattice disorder. We also test the approximation consisting in considering impurities at small values of x as bare mass defects, neglecting their chemical identity, and discuss its validity.

Fibre-base duality of 5d KK theories

We study circle compactifications of 6d superconformal field theories giving rise to 5d rank 1 and rank 2 Kaluza-Klein theories. We realise the resulting theories as M-theory compactifications on local Calabi-Yau 3-folds and match the prepotentials from geometry and field theory. One novelty in our approach is that we include explicit dependence on bare gauge couplings and mass parameters in the description which in turn leads to an accurate parametrisation of the prepotential including all parameters of the field theory. We find that the resulting geometries admit “fibre-base” duality which relates their six-dimensional origin with the purely five-dimensional quantum field theory interpretation. The fibre-base duality is realised simply by swapping base and fibre curves of compact surfaces in the local Calabi-Yau which can be viewed as the total space of the anti-canonical bundle over such surfaces. Our results show that such swappings precisely occur for surfaces with a zero self-intersection of the base curve and result in an exchange of the 6d and 5d pictures.