Scalar Condensate Research Articles

Relaxation times for disoriented isospin condensates in high energy heavy ion collisions

Fluctuations between charged and neutral kaons measured by the ALICE Collaboration in Pb-Pb collisions at the CERN Large Hadron Collider (LHC) exceed conventional explanations. Previously it was shown that if the scalar condensate is accompanied by an electrically neutral isospin-1 field then the combination can produce large equilibrium fluctuations where 〈u¯u〉≠〈d¯d〉. Hadronizing strange and antistrange quarks might then strongly fluctuate between charged (us¯ or su¯) and neutral (ds¯ or sd¯) kaons. Here, we estimate the times for the condensates to achieve their equilibrium probability distributions within causal volumes in high energy heavy ion collisions. This is achieved by modeling the temperature dependence of the condensates, mesonic collective excitations, decay rates of the associated fields, and employing the Langevin and Fokker-Planck equations. Within this model, we find that the equilibration times are short compared with the expansion time, making disoriented isospin condensates a viable explanation for the anomalous fluctuations observed at the LHC. Published by the American Physical Society 2025

Effect of scalar condensation on fermionic pole-skipping

In this paper, we investigated the holographic fermionic pole-skipping phenomena for a class of interacting theory in a charged AdS black hole background. We have studied two types of fermion-scalar interactions in the bulk: dipole and Yukawa type interaction. Depending upon the interaction we introduced both real and charged scalar fields. We have particularly analyzed the effect of scalar condensation on the fermionic pole-skipping points and discussed their behaviour near critical temperatures.

Lattice study on finite density QC2D towards zero temperature

We investigate the phase structure and the equation of state (EoS) for dense two-color QCD (QC2D) at low temperature (T = 40 MeV, 324 lattice) for the purpose of extending our previous works [1, 2] at T = 80 MeV (164 lattice). Indeed, a rich phase structure below the pseudo-critical temperature Tc as a function of quark chemical potential μ has been revealed, but finite volume effects in a high-density regime sometimes cause a wrong understanding. Therefore, it is important to investigate the temperature dependence down to zero temperature with large-volume simulations. By performing 324 simulations, we obtain essentially similar results to the previous ones, but we are now allowed to get a fine understanding of the phase structure via the temperature dependence. Most importantly, we find that the hadronic-matter phase, which is composed of thermally excited hadrons, shrinks with decreasing temperature and that the diquark condensate scales as ⟨qq⟩ ∝ μ2 in the BCS phase, a property missing at T = 80 MeV. From careful analyses, furthermore, we confirm a tentative conclusion that the topological susceptibility is independent of μ. We also show the temperature dependence of the pressure, internal energy, and sound velocity as a function of μ. The pressure increases around the hadronic-superfluid phase transition more rapidly at the lower temperature, while the temperature dependence of the sound velocity is invisible. Breaking of the conformal bound is also confirmed thanks to the smaller statistical error.

Enhanced primordial gravitational waves from a stiff postinflationary era due to an oscillating inflaton

We investigate two classes of inflationary models, which lead to a stiff period after inflation that boosts the signal of primordial gravitational waves (GWs). In both families of models studied, we consider an oscillating scalar condensate, which when far away from the minimum is overdamped by a warped kinetic term, la α-attractors. This leads to successful inflation. The oscillating condensate is in danger of becoming fragmented by resonant effects when nonlinearities take over. Consequently, the stiff phase cannot be prolonged enough to enhance primordial GWs at frequencies observable in the near future for low orders of the envisaged scalar potential. However, this is not the case for a higher-order scalar potential. Indeed, we show that this case results in a boosted GW spectrum that overlaps with future observations without generating too much GW radiation to destabilize big bang nucleosynthesis. For example, taking α=O(1), we find that the GW signal can be safely enhanced up to ΩGW(f)∼10−11 at frequency f∼102 Hz, which will be observable by the Einstein Telescope. Our mechanism ends up with a characteristic GW spectrum, which if observed, can lead to the determination of the inflation energy scale, the reheating temperature, and the shape (steepness) of the scalar potential around the minimum. Published by the American Physical Society 2024

Photon propagation in a charged Bose–Einstein condensate model

We consider the propagation of photons in a model of a charged scalar Bose-Einstein (BE) condensate. We determine the dispersion relations of the collective modes, as well as the photon polarization tensor and the dielectric constant in the model. Two modes correspond to the transverse photon polarizations, with dispersion relations of the usual form for transverse photons in a plasma. The other two modes, denoted as the (±)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\pm )$$\\end{document} modes, are combinations of the longitudinal photon and the massive scalar field. Their dispersion relations behave very differently as functions of momentum. The (+)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(+)$$\\end{document} mode dispersion relation increases steadily and remains greater than the momentum as the momentum increases. The dispersion relation of the (-)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(-)$$\\end{document} mode decreases in a given momentum range, with the group velocity being negative in that range, while in another range it increases steadily but remains smaller than the momentum, akin to the situation in a medium with an index of refraction greater than 1. We consider the non-relativistic limit of the (±)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\pm )$$\\end{document} dispersion relations and discuss some aspects of the results. We also determine the wavefunctions of the (±)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\pm )$$\\end{document} modes, which are useful to obtain the corrections to the dispersion relations, e.g., imaginary parts due to the damping effects and/or the effects of scattering, due to the interactions with the excitations of the system. The results can be useful in various physical contexts that have been considered in the literature involving the electrodynamics of a charged scalar BE condensate.

Topological susceptibility and axion potential in two-flavor superconductive quark matter

We study the potential of the axion, a, of Quantum Chromodynamics, in the two-flavor color superconducting phase of cold and dense quark matter. We adopt a Nambu-Jona-Lasinio-like model. Our interaction contains two terms, one preserving and one breaking the U(1)A symmetry: the latter is responsible of the coupling of axions to quarks. We introduce two quark condensates, hL and hR, describing condensation for left-handed and right-handed quarks respectively; we then study the loci of the minima of the thermodynamic potential, Ω, in the (hL,hR) plane, noticing how the instanton-induced interaction favors condensation in the scalar channel when the θ angle, θ=a/fa, vanishes. Increasing θ we find a phase transition where the scalar condensate rotates into a pseudoscalar one. We present an analytical result for the topological susceptibility, χ, in the superconductive phase, which stands both at zero and at finite temperature. Finally, we compute the axion mass and its self-coupling. In particular, the axion mass ma is related to the full topological susceptibility via χ=ma2fa2; hence our result for χ gives an analytical result for ma in the superconductive phase of high-density Quantum Chromodynamics. Published by the American Physical Society 2024

Stairway to equilibrium entropy

We compute the time evolution of the nonequilibrium entropy in the homogeneous isotropization dynamics of the 1 R-Charge Black Hole model, which has a critical point in its conformal phase diagram defined at finite temperature and R-charge density. We also evaluate the time evolution of the pressure anisotropy and the scalar condensate of the medium. We disclose a new feature (not present in the Bjorken flow dynamics analyzed in previous works), which is observed for all the analyzed initial data: the formation of a periodic sequence of several close plateaus in the form of a stairway for the entropy density near thermodynamic equilibrium. We find that the period of plateau formation in the stairway is half the period of oscillations of the slowest quasinormal mode of the system, which is therefore strongly tied to the late-time dissipative dynamics of the system associated with the irreversibility of entropy production. For the particular case of the purely thermal Supersymmetric Yang-Mills plasma at zero density and vanishing scalar condensate, we find that the period of the stairway is half the period of oscillations of the slowest quasinormal mode associated with the late-time equilibration of the pressure anisotropy of the fluid, while at finite chemical potential the slowest quasinormal mode of the system is associated with the late-time equilibration of the scalar condensate. Published by the American Physical Society 2024

Fate of oscillating homogeneous ℤ2-symmetric scalar condensates in the early Universe

Dark matter, if represented by a ℤ2-symmetric scalar field, can manifest as both particles and condensates. In this paper, we study the evolution of an oscillating homogeneous condensate of a ℤ2-symmetric scalar field in a thermal plasma in an FLRW universe. We focus on the perturbative regime where the oscillation amplitude is sufficiently small so that parametric resonance is inefficient. This perturbative regime necessarily comprises the late stage of the condensate decay and determines its fate. The coupled coarse-grained equations of motion for the condensate, radiation, and spacetime are derived from first principles using nonequilibrium quantum field theory. We obtain analytical expressions for the relevant microscopic quantities that enter the equations of motion and solve the latter numerically. We find that there is always a nonvanishing relic abundance for a condensate with a ℤ2 symmetry that is not spontaneously broken. This is because its decay rate decreases faster than the Hubble parameter at late times due to either the amplitude dependence or the temperature dependence in the condensate decay rate. Consequently, accounting for the condensate contribution to the overall dark matter relic density is essential for ℤ2 scalar singlet dark matter.

Phenomenology of isospin-symmetry breaking with vector mesons

We study the effect of isospin-symmetry breaking in the framework of the extended linear σ model in vacuum. In this model, several particles mix with each other at tree level, due to the three nonzero scalar condensates (nonstrange, strange, isospin). We resolve these mixings with the help of various field transformations. We compute all possible meson mixings and decay widths at tree level and perform a χ2 fit to PDG data. A very good fit is found if we exclude the (very small ∼130 keV) ω→ππ decay. We also investigate the violation of Dashen’s theorem. Published by the American Physical Society 2024

Disoriented isospin condensates may be the source of anomalous kaon correlations measured in Pb-Pb collisions at sNN=2.76 TeV

The magnitude of fluctuations between charged and neutral kaons measured by the ALICE Collaboration in heavy-ion collisions at the LHC exceeds conventional explanation. Here it is shown that if the scalar condensate, which is typically associated with chiral symmetry, is accompanied by an isospin=1 field, then the combination can produce large fluctuations where 〈u¯u〉≠〈d¯d〉. Hadronizing strange and antistrange quarks might then strongly fluctuate between charged (us¯ or su¯) and neutral (ds¯ or sd¯) kaons. Published by the American Physical Society 2024

Pyrene monomer-excimer dynamics to reveal molecular organization in mesoporous hybrid silica films.

Self-assembly and characteristics of hybrid mesoporous silica film templates remain a subject of inquiry. The short time scale of the inorganic condensation and formation of micelles makes our understanding of this process insufficient. To provide an insight into the evaporation-induced self-assembly of such films, we synthesized an efficient molecular probe of the triethoxysilane precursor bearing a pyrene derivative. The probe was introduced into the porous film at the synthesis stage through the sol-gel co-condensation method. At different synthesis stages, the emission of pyrene moieties was measured by fluorescence spectroscopy, revealing the placement of probes within the film. We also report dynamic excimer formation upon template removal. Moreover, we evaluate the influence of several parameters on the pyrene excimer formation phenomenon. The pore geometry, probe concentration, and the presence of another organosilane precursor are investigated in this work.

Decay of ALP condensates via gravitation-induced resonance

Oscillating scalar field condensates induce small amplitudeoscillations of the Hubble parameter which can induce a decay of thecondensate due to a parametric resonance instability [1]. Weshow that this instability can lead to the decay of the coherence ofthe condensate of axion-like particle (ALP) fields during theradiation phase of standard cosmology for rather generic ALP parametervalues, with possible implications for certain experiments aiming to searchfor ALP candidates. As an example, we study the application of thisinstability to the QCD axion. We also study the magnitude of theinduced entropy fluctuations.

When tadpoles matter: one-loop corrections for spectator Higgs in inflation

We consider the classical attractor regime of the spectator Abelian Higgs model in power-law inflation, and compute the one-loop corrections to its evolution. For computations we utilize dimensional regularization and the propagators in the unitary gauge. The corrections to both the scalar condensate and the energy-momentum tensor exhibit secular ultraviolet contributions, that tend to slow down the rolling of the scalar down its potential, and drive it away from the classical attractor. These corrections need not be suppressed if the U(1) charge is much larger than the scalar self-coupling, which is seen already in flat space. In addition, at late times the secular corrections necessarily invalidate the perturbative loop expansion. We find the late time secular corrections to be captured by the renormalization group, which opens up the possibility to resum them past the breakdown of perturbativity.

Model for the propagation of fermions in a Bose-Einstein condensate

We consider the dispersion relations of fermions that propagate in the background of a scalar Bose-Einstein condensate. Some illustrative examples are discussed using simple Yukawa-type coupling models between the fermions and the scalar fields. The dispersion relations are determined explicitly in those cases, to the lowest order. The method also allows to determine the corrections to the dispersion relations due to the interactions with the excitations of the Bose-Einstein condensate. Possible applications of the results to the case of neutrinos are indicated.

Hadronic structure on the light front. VII. Pions and kaons and their partonic distributions

This work is a continuation in our series of papers, that addresses quark models of hadronic structure on the light front, motivated by the QCD vacuum structure and lattice results. The spontaneous breaking of chiral symmetry on the light front, is shown to parallel that in the rest frame, where the non-local instanton induced $^\prime$t Hooft interaction plays a central role. By rewriting this interaction solely in terms of the good component of the fermionic field, a scalar chiral condensate emerges in the mean-field approximation, which is identical to the one obtained in the rest frame. The pions and kaons emerge as deeply bound Goldstone modes in the chiral limit, with the scalar-isoscalar sigma meson mode as a threshold state with zero binding. We explicitly derive the light front distribution amplitudes (DAs) and partonic functions (PDFs) for these mesons. The DAs and PDFs are in good agreement with those extracted from the QCD instanton vacuum in the rest frame, using the large momentum effective theory (LaMET). The QCD evolved DAs and PDFs compare well with available measurements, as well as recent lattice results.

Catalyzation of supersolidity in binary dipolar condensates

In this work, the authors show realistic conditions for which doping an unmodulated scalar condensate with a second component catalyzes droplet nucleation and supersolidity. In miscible mixtures, droplet nucleation may be induced even by a surprisingly small impurity doping due to the effective modification of the relative dipolar strength. As a result, binary dipolar condensates present different ground-state phases, most intriguingly the possibility of realizing an interacting two-fluid supersolid.

Descalarization by quenching charged hairy black hole in asymptotically AdS spacetime

In this work, we study the real-time dynamics of the charged hairy black hole with the time-dependent source of scalar field in asymptotically anti-de Sitter (AdS) spacetime. The numerical results reveal a novel descalarization mechanism. In order to obtain the hairy black hole as the initial data for the quench process, we first analyze the quasi-normal modes of the massive complex scalar field on the Reissner-Nordström anti-de Sitter (RN-AdS) black hole background. We find the dominant unstable modes for large and small RN-AdS black holes come from the zero-damped modes and AdS modes, respectively. Then, the unstable RN-AdS black holes are perturbed to trigger the transition to hairy black holes. With the hairy black hole in hand, we specify a time dependent scalar source for the system. As the source is turned on, the electric charge, energy and scalar condensation of the system start to oscillate with the entropy increasing monotonically. Finally, with the decay of the scalar source, the system gradually settles down to a new state. Interestingly, the final state of the evolution could be a hairy black hole with less scalar condensation, a RN-AdS black hole or a Schwarzschild-AdS black hole, which depends on the quench strength. However, as long as the quench strength is large enough, the system always loses all the electric charge and converges to the Schwarzschild-AdS black hole.

QCD sum rule analysis of heavy quarkonium states in magnetized matter: Effects of magnetic and inverse magnetic catalysis

In-medium masses of the $1S$ and $1P$ states of heavy quarkonia are investigated in the magnetized asymmetric nuclear medium, accounting for the Dirac sea effects, using a combined approach of chiral effective model and QCD sum rule method. Masses are calculated from the in-medium scalar and twist-2 gluon condensates, calculated within the chiral model. The gluon condensate is simulated through the scalar dilaton field, $\ensuremath{\chi}$ introduced in the model through a scale-invariance breaking logarithmic potential. Contribution of the Dirac sea is incorporated through the nucleonic tadpole diagrams. Treating the scalar fields as classical, the dilaton field, $\ensuremath{\chi}$, the isoscalar nonstrange $\ensuremath{\sigma}(\ensuremath{\sim}(⟨\overline{u}u⟩+⟨\overline{d}d⟩))$, strange $\ensuremath{\zeta}(\ensuremath{\sim}⟨\overline{s}s⟩)$ and isovector $\ensuremath{\delta}(\ensuremath{\sim}(⟨\overline{u}u⟩\ensuremath{-}⟨\overline{d}d⟩))$ fields, are obtained by solving their coupled equations of motion as derived from the chiral model Lagrangian. The effects of magnetic field are incorporated through the Dirac sea as well as the Landau energy levels of the protons, and the anomalous magnetic moments of the nucleons. The scalar fields modify appreciably with magnetic field due to the Dirac sea contribution. In-medium masses of the charmonium and bottomonium ground states are observed to have significant modifications with magnetic field due to the effects of (inverse) magnetic catalysis. In presence of an external magnetic field, there is mixing between the longitudinal component of the vector and the pseudoscalar mesons (PV mixing) in both quarkonia sectors, leading to a rise (drop) of the masses of $J/{\ensuremath{\psi}}^{||}({\ensuremath{\eta}}_{c})$ and ${\mathrm{\ensuremath{\Upsilon}}}^{||}(1S)({\ensuremath{\eta}}_{b})$ states. These might show in the experimental observables, e.g., the dilepton spectra in the noncentral, ultrarelativistic heavy ion collision experiments at RHIC and LHC, where the produced magnetic field is huge.

Quantization of a charged scalar field on a charged black hole background

We study the canonical quantization of a massless charged scalar field on a Reissner-Nordstr\"om black hole background. Our aim is to construct analogs of the standard Boulware, Unruh and Hartle-Hawking quantum states which can be defined for a neutral scalar field, and to explore their physical properties by computing differences in expectation values of the scalar field condensate, current and stress-energy tensor operators between two quantum states. Each of these three states has a non-time-reversal-invariant past and future charged field generalization, whose properties are similar to those of the corresponding past and future states for a neutral scalar field on a Kerr black hole. In addition, we present some tentative, time-reversal-invariant, equilibrium states. The first is a ``Boulware''-like state which is as empty as possible at both future and past null infinity. Second, we posit a ``Hartle-Hawking''-like state which may correspond to a thermal distribution of particles. The construction of both these latter states relies on the use of nonstandard commutation relations for the creation and annihilation operators pertaining to superradiant modes.

Electroweak asymmetric early Universe via a scalar condensate

Finite temperature effects in the Standard Model tend to restore the electroweak symmetry in the early universe, but new fields coupled to the Higgs field may as well reverse this tendency, leading to the so-called electroweak symmetry nonrestoration (EW SNR) scenario. Previous works on EW SNR often assume that the reversal is due to the thermal fluctuations of new fields with negative quartic couplings to the Higgs, and they tend to find that a large number of new fields are required. We observe that EW SNR can be minimally realized if the field(s) coupled to the Higgs field develop(s) a stable condensate. We show that one complex scalar field with a sufficiently large global-charge asymmetry can develop a condensate as an outcome of thermalization and keep the electroweak symmetry broken up to temperatures well above the electroweak scale. In addition to providing a minimal benchmark model, our work hints on a class of models involving scalar condensates that yield electroweak symmetry nonrestoration in the early universe.