Fl. Stancu
We discuss the charge conjugation quantum number for tetraquarks or meson-meson molecules, seen as possible interpretations of the newly found $XYZ$ charmonium-like resonances.
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Why do we see certain types of strongly interacting elementary particles and not others? This question was posed over 50 years ago in the context of the quark model. M. Gell-Mann and G. Zweig proposed that the known mesons were $q \bar q$ and baryons $qqq$, with quarks known at the time $u$ ("up"), $d$ ("down"), and $s$ ("strange") having charges (2/3,-1/3,-1/3). Mesons and baryons would then have integral charges. Mesons such as $qq \bar q \bar q$ and baryons such as $qqqq \bar q$ would also have integral charges. Why weren't they seen? They have now been seen, but only with additional heavy …
The commonly used $γ_μ} Pomeron-quark coupling changes its sign under charge conjugation, in contradiction to the property of Pomeron. I show that the Pomeron-quark coupling is tensorial and is invariant under the charge conjugation.
We introduce the hypothesis that diquarks and antidiquarks in tetraquarks are separated by a potential barrier. We show that this notion can answer satisfactorily long standing questions challenging the diquark-antidiquark model of exotic resonances. The tetraquark description of X and Z resonances is shown to be compatible with present limits on the non-observation of charged partners X^+-, of the X(3872) and the absence of a hyperfine splitting between two different neutral states. In the same picture, Z_c and Z_b particles are expected to form complete isospin triplets plus singlets. It is …
We show that the $1/N_c$ rotational corrections to $g_A$, derived using the semiclassical quantization scheme in the NJL model, possess correct properties under charge conjugation.
Recent theory results on direct production of resonances with positive charge conjugation in electron-positron annihilation are reviewed. The strong model dependence is emphasized, with predictions varying between 0.03 eV and 0.43 eV for the charmonium state with $J^{PC} = 1^{++}$ and between 0.16 eV and 4.25 eV for the state with $J^{PC} = 2^{++}$. For the state with $J^{PC} = 0^{++}$ the cross section is of $\cal{O}$ $(m^2_e/M^2_χ)$ and thus negligeable for all practical purpose. The importance of the relative phase of the production amplitude is emphasized.
This talk reviews the last applications of the covariant quark model for studying the properties of the multiquark states: B_s-meson (quark-antiquark state), light baryons (three-quark states) and tetraquark (four-quark state). The form factors of the B(B_s)-> P(V)-transitions are evaluated in the full kinematical region of momentum transfer squared. The widths of some B_s-nonleptonic decays are calculated. The static properties of the proton and neutron, and the Λ-hyperon (magnetic moments and charge radii) and the behavior of the nucleon form factors at low momentum transfers are described. …
Alice electrodynamics (AED) is a theory of electrodynamics in which charge conjugation is a local gauge symmetry. In this paper we investigate a charge instability in alice electrodynamics in (2+1)-dimensions due to this local charge conjugation. The instability manifests itself through the creation of a pair of alice fluxes. The final state is one in which the charge is completely delocalized, i.e., it is carried as cheshire charge by the flux pair that gets infinitely separated. We determine the decay rate in terms of the parameters of the model. The relation of this phenomenon with other sa…
This article proves that according to the principles of quantum mechanics the existence of elementary particles of negative mass is physically plausible. Heisenberg's uncertainty principle plays an important role in this demonstration. By reversing time, charge and mass are conjugated and the symmetry group is that of the Poincare with space-time reflections (full Poincare group). Particles that tunnel from the future time-like cone to the past time-like cone move backward in time with negative mass (and energy). These particles are interpreted as antiparticles of positive mass (and energy) th…
In this essay, an {\it ab initio} study of the self/anti-self charge conjugate $(1/2,\,0)\oplus(0,\,1/2)$ representation space is presented. Incompatibility of self/anti-self charge conjugation with helicity eigenstates and gauge interactions is demonstrated. Parity violation is seen as an intrinsic part of the self/anti-self charge conjugate construct. From a phenomenological point of view, an essential part of the theory is the Bargmann-Wightman-Wigner-type boson, where a boson and its antiboson carry opposite relative intrinsic parity.
Black hole formation (BHF) in hadron collisions is a subject of great interest. Hard quark-quark collisions are generally associated with the production of particles at large transverse momenta or with high multiplicities. If BHF occurs, we might expect large violations of baryon number, charge conjugation (C), parity (P), strangeness, isospin, etc. in such processes. C and P have not been well tested in hadronic interactions. I propose new tests of C and P that can be adapted to a variety of BHF scenarios. These may provide more sensitive searches for BHF or other new physics at existing coll…
A new understanding of the stability of self-interacting dark matter is pointed out, based on the simplest spontaneously broken Abelian $U(1)$ gauge model with one complex scalar and one Dirac fermion. The key is the imposition of dark charge conjugation symmetry. It allows the possible existence of two stable particles: the Dirac fermion and the vector gauge boson which acts as a light mediator for the former's self-interaction. Since this light mediator does not decay, it avoids the strong cosmological constraints recently obtained for all such models where the light mediator decays into sta…
We discuss anomalies associated with outer automorphisms in gauge theories based on classical groups, namely charge conjugations for $SU(N)$ and parities for $SO(2r)$. We emphasize the inequivalence (yet related by a flavor transformation) between two versions of charge conjugation for $SU(2k)$, $SO(2r)$, and $E_6$ symmetries. The subgroups that commute with the outer automorphisms are identified. Some charge conjugations can lead to a paradox, which is resolved by the observation that they are anomalous and hence not symmetries. We then discuss anomaly matching conditions that involve the cha…
The phase structure of two-flavor QCD is investigated at real isospin and imaginary quark chemical potentials by using the Polyakov-loop extended Nambu--Jona-Lasinio model. In the region, parity symmetry is spontaneously broken by the pion superfluidity phase transition, whereas charge-conjugation symmetry is spontaneously violated by the Roberge-Weiss transition. The chiral (deconfinement) crossover at zero isospin and quark chemical potentials is a remnant of the parity (charge-conjugation) violation. The interplay between the parity and charge-conjugation violations are analyzed, and it is …
The pion form factor is calculated in the framework of the charge-conjugation invariant Covariant Spectator Theory. This formalism is established in Minkowski space and the calculation is set up in momentum space. In a previous calculation we included only the leading pole coming from the spectator quark (referred to as the relativistic impulse approximation). In this paper we also include the contributions from the poles of the quark which interacts with the photon and average over all poles in both the upper and lower half planes in order to preserve charge conjugation invariance (referred t…
This essay presents a new asymmetry that arises from the interplay of charge conjugation and Lense-Thirring effect. When applied to Majorana neutrinos, the effects predicts nu_e <-> overline{nu}_e oscillations in gravitational environments with rotating sources. Parameters associated with astrophysical environments indicate that the presented effect is presently unobservable for solar neutrinos. But, it will play an important role in supernova explosions, and carries relevance for the observed matter-antimatter asymmetry in the universe.
The well known charge conjugation violating interactions in the Standard Model increase neutrino- and decrease anti-neutrino- nucleon cross sections. This impacts neutrino transport in core collapse supernovae through "recoil" corrections of order the neutrino energy $k$ over the nucleon mass $M$. All $k/M$ corrections to neutrino transport deep inside a protoneutron star are calculated from angular integrals of the Boltzmann equation. We find these corrections significantly modify neutrino currents at high temperatures. This produces a large mu and tau number for the protoneutron star and can…
We study the threshold enhancement effects of baryon-anti-baryon systems in $J/ψ$ decays at BES using parity $P$, charge conjugation $C$, and flavor SU(3) symmetries. The $P$ and $C$ symmetries restrict the $p\bar p$ in $J/ψ\to γp\bar p$ to be in a state with $C=+1$, while the $p\bar p$ in $J/ψ\to π^0 p\bar p$ to be with $C=-1$. Combining the $C$ and $P$ symmetries with flavor SU(3) symmetry, i.e. the CPS symmetry, we find that the $Λ\bar p$ system cannot be in $0^+$ and $0^-$ states in $J/ψ\to K^+ Λ\bar p$. We provide a consistent explanation of observation and non-observation of near thresho…
We investigate the possibility to explain the MiniBooNE anomaly by CPT and Lorentz symmetry violating neutrino-antineutrino oscillations in a two generation framework. We work with four non-zero CPT-violating parameters that allow for resonant enhancements in neutrino-antineutrino oscillation phenomena in vacuo which are suitably described in terms of charge conjugation eigenstates of the system. We study the relation between the flavor, charge conjugation and mass eigenbasis of neutrino-antineutrino oscillations and examine the interplay between the available CPT-violating parameter space and…
Dark Charge Conjugation and Complementary Constraints from $D^0$ Mixing and Rare Decays with Massless Dark Photons
该研究探究暗电荷共轭对D⁰稀有衰变的组织作用，结合D⁰混合及相关稀有衰变约束，揭示中性粲介子混合与稀有衰变在探测味改变相互作用时的互补性。
Charge conjugation (C) and Parity (P) are exact symmetries at theta =pi and Theta = mu/(iT)=pi, where theta is the parameter of the so-called theta-vacuum, mu is the imaginary quark-number chemical potential and T is the temperature. Spontaneous breakings of these discrete symmetries are investigated by the the Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model. At zero T, P symmetry is spontaneously broken while C symmetry is conserved. As T increases, P symmetry is restored just after C symmetry is spontaneously broken, so that either P or C symmetry or both the symmetries are spontaneo…
We discuss flavor symmetries in left-right symmetric theories. We show that such frameworks are a different environment for flavor symmetry model building compared to the usually considered cases. This does not only concern the need to obey the enlarged gauge structure, but also more subtle issues with respect to residual symmetries. Furthermore, if the discrete left-right symmetry is charge conjugation, potential inconsistencies between the flavor and charge conjugation symmetries should be taken care of. In our predictive model based on $A_4$ we analyze the correlations between the smallest …
Within the minimal Left-Right (LR) symmetric model we revisit the predictions for the kaon CP violating observables $\varepsilon$ and $\varepsilon'$ in correlation with the neutron electric dipole moment. We perform a complete study of the cross constraints on the model parameters, phases and the $M_{W_R}$ scale, considering the two cases of extended parity or charge conjugation as LR discrete symmetries, together with the possible presence of a Peccei-Quinn symmetry. We discuss in particular two scenarios: whether the Standard Model saturates the experimental value of $\varepsilon'/\varepsilo…
Charge-conjugation asymmetry and molecular content: the $D_{s0}^\ast(2317)^\pm$ in matter
本研究分析了致密核介质对 $D_{s0}^\ast(2317)^\pm$ 和 $D_{s1}(2460)^\pm$ 的修改，发现由于 K 介子与反 K 介子同核子相互作用不同，粒子-反粒子在物质中表现出极大的电荷共轭不对称性，该特性可用于约束这些奇特态的内部结构。
We consider the production of the $η_c$ and $χ_{cJ}$ states recoiled with a photon up to $\mathcal{O}(α_s v^2)$ at BESIII and B-factories within the frame of NRQCD factorization. With the corrections, we revisit the numerical calculations to the cross sections for the $η_c(nS)$ and the $χ_{cJ}(mP)$ states. We argue that the search for $XYZ$ states with even charge conjugation such as $X(3872)$, $X(3940)$, $X(4160)$, and $X(4350)$ recoiled with a photon at BESIII may help clarify the nature of these states. For completeness, the production of charmonium with even charge conjugation recoiled wit…
Imaginary Rotation Breaks Charge Conjugation in Hot QCD
本研究从算符恒等式出发推导密度算子恒等式，将虚旋转下的热QCD系统映射到Roberge-Weiss点，解析得到无质量夸克味下的相变点，并给出格点QCD检验条件。
The existence of three generations of neutrinos(charged leptons/quarks) and their mass mixing are deep mysteries of our universe. Recently, Majorana's spirit returns in modern condensed matter physics -- in the context of topological Majorana zero modes in certain classes of topological superconductors(TSCs). In this paper, we attempt to investigate the topological nature of the neutrino by assuming that a relativistic Majorana fermion can be divided into four topological Majorana zero modes at cutoff energy scale, e.g. planck scale. We begin with an exactly solvable $1$D lattice model which r…
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 mech…
It is shown that the specific "charge conjugation" transformation used to define the Majorana fermions in the conventional seesaw mechanism, namely $(ν_{R})^{C}=C\bar{ν_{R}}^{T}$ for a chiral fermion $ν_{R}$ (and similarly for $ν_{L}$), is a hidden symmetry associated with CP symmetry, and thus it formally holds independently of the P- and C-violating terms in the CP invariant Lagrangian and it is in principle applicable to charged leptons and quarks as well. This hidden symmetry, however, is not supported by a consistent unitary operator and thus it leads to mathematical (operatorial) ambigui…
We report an unexpected theoretical discovery of a spin one half matter field with mass dimension one. It is based on a complete set of eigenspinors of the charge conjugation operator. Due to its unusual properties with respect to charge conjugation and parity it belongs to a non standard Wigner class. Consequently, the theory exhibits non-locality with (CPT)^2 = - I. Its dominant interaction with known forms of matter is via Higgs, and with gravity. This aspect leads us to contemplate it as a first-principle candidate for dark matter.
The Roberge-Weiss (RW) phase transition in the imaginary chemical potential region is analyzed by the Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model. In the RW phase transition, the charge-conjugation symmetry is spontaneously broken, while the extended Z3 symmetry (the RW periodicity) is preserved. The RW transition is of second order at the endpoint. At the zero chemical potential, a crossover deconfinement transition appears as a remnant of the second-order RW phase transition at the endpoint, while the charge-conjugation symmetry is always preserved.
In this work we investigate the interaction between spin-zero and spin-one monopoles by making use of an effective field theory based on two-body and four-body interaction parts. In particular, we analyze the formation of bound state of monopole-antimonopole (i.e. monopolium). The magnetic-charge conjugation symmetry is studied in analogy to the usual charge conjugation to define a particle basis, for which we find bound-state solutions with relatively small binding energies and which allows us to identify the bounds on the parameters in the effective Lagrangians. Estimations of their masses, …
We suggest that the Majorana neutrino should be regarded as a Bogoliubov quasiparticle that is consistently understood only by use of a relativistic analogue of the Bogoliubov transformation. The unitary charge conjugation condition ${\cal C}ψ{\cal C}^{\dagger}=ψ$ is not maintained in the definition of a quantum Majorana fermion from a Weyl fermion. This is remedied by the Bogoliubov transformation accompanying a redefinition of the charge conjugation properties of vacuum, such that a C-noninvariant fermion number violating term (condensate) is converted to a Dirac mass. We also comment on the…
Meson molecules in strong magnetic fields: non-monotonic evolution of the charged pion and kaon energies
基于玻恩-奥本海默近似，研究强磁场中带电赝标量介子（π+和K+）的束缚态，发现维度约化与介子-介子相互作用导致散射主导、分子态和紧致多夸克态三种区域，大磁场下出现弱束缚分子态。
Core collapse supernovae are gigantic explosions of massive stars that radiate 99% of their energy in neutrinos. This provides a unique opportunity for large scale parity or charge conjugation violation. Parity violation in a strong magnetic field could lead to an asymmetry in the neutrino radiation and recoil of the newly formed neutron star. Charge conjugation violation in the neutrino-nucleon interaction reduces the ratio of neutrons to protons in the neutrino driven wind above the neutron star. This is a problem for r-process nucleosynthesis in this wind. On earth, parity violation is an e…
Mass dimension one quantum fields, constructed upon eigenspinors of the charge conjugation operator with dual helicity (ELKO), are prime candidates to describe dark matter. Their interaction with the photon and the proton, in scattering processes, are here explored and discussed, using both the standard QFT with a Maxwell gauge field and a generalized QFT also involving a Podolsky gauge sector. Renormalization and radiative corrections are analyzed in the ELKO setup, in the context of a generalized spinor dual and the twisted conjugation, both yielding unitarity. Several applications are scrut…
We discuss the ``spectroscopy'' of gluonic states in systems with two space dimensions, using simple models to mimic the results of lattice gauge theory computations. We first discuss the quantum numbers of these systems, including charge conjugation. Two types of systems are discussed in detail: ``gluelumps'' which have a heavy adjoint color charge at the origin and glueballs which are composed entirely of glue. Both systems are discussed using the bag model and the flux tube model. For glueballs the model spectra are compared with the resulst of Teper. Both models capture many features of th…
CPT, Majorana fermions, and particle physics beyond the Standard Model
本文回顾CPT定理并定义Majorana费米子，阐明其与Weyl及Dirac场的关系，并探讨其在标准模型之外物理场景（如中微子质量、宇宙重子不对称、大统一理论与超对称）中的应用。
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