arXiv subjects

She-Sheng Xue

Publications and source records attributed to She-Sheng Xue.

At least 163 records · Page 9Linked to original sources

arXiv1997

The twisted Wilson fermion for the Standard Model on a lattice

We present a preliminary study of a chiral-gauge-invariant Wilson term for the Standard Model on a lattice. In the strong coupling limit for doublers, this Wilson term shows that the doublers of leptons (quarks) are anti-baryons (anti-leptoquarks), and they are decoupled by getting gauge invariant masses. We discuss that the possibility of achieving the low-energy Standard Model could be realized by the ``three-fermion-cuts'' at the weak coupling limit for normal modes, where baryons and leptoquarks dissolve into their constituents.

hep-lat↗

arXiv1997

Further discussions on a possible lattice chiral gauge theory

In a possible $SU_L(2)$ lattice chiral gauge theory with a large multifermion coupling, we try to further clarify the threshold phenomenon: the possibility that the right-handed three-fermion state turns into the virtual states of its constituents (free chiral fermions) in the low-energy limit. Provided this phenomenon occurs, we discuss the chiral gauge coupling, Ward identities and the gauge anomaly within the gauge-invariant prescription of the perturbative chiral gauge theory.

hep-lat↗

arXiv1997

Neutrino masses and mixings

We propose a novel theoretical understanding of neutrino masses and mixings, which is attributed to the intrinsic vector-like feature of the regularized Standard Model at short distances. We try to explain the smallness of Dirac neutrino masses and the decoupling of the right-handed neutrino as a free particle. Neutrino masses and mixing angles are completely related to each other in the Schwinger-Dyson equations for their self-energy functions. The solutions to these equations and a possible pattern of masses and mixings are discussed.

hep-ph↗

arXiv1997

Mass generation of the lepton sector

We discuss the necessity of a right-handed Weyl neutrino due to the vector-like phenomenon of the regularized Standard Model. It is shown that this right-handed neutrino is decoupled from low energies as a free particle, and Dirac neutrino masses are very small. We suggest gauge-invariant couplings between down quarks and charged leptons so that charged leptons acquire masses without extra Goldstone modes. By examining Schwinger-Dyson equations for lepton self-energy functions, we show that the neutrinos get their Dirac masses via explicit symmetry breakings that attribute to the mixing between neutrinos and charged leptons. An analysis of these Dyson equations gives the four relationships between inter-generation mixing angles and lepton masses.

hep-ph↗

arXiv1997

Fine-tuning the low-energy physics

In this article we discuss the problem of the extreme fine-tuning necessary to achieve the top quark mass scale $m_t$ within the dynamical symmetry breaking of the phenomenological $t \bar t$ condensate model. Inspired by the vector-like phenomenon of chiral gauge theories at short distances, we postulate that the $W^\pm$-gauge bosons possess a vector-like gauge coupling and contribute to the gap-equations of quark self-energy functions in the high-energy region. We find that the gap-equations of different charge sectors are coupled, and as a result the unnatural fine-tuning is overcome and the ratio of the top and bottom masses is related to the electric charge: $({m_b\over m_t})^2\simeq {α\over3π}$, provided the quadratic divergence is removed by setting the four-fermion coupling $G=4+o({m_b^2\over m_t^2})$.

hep-ph↗

arXiv1997

Lattice Formulation of the Standard Model

Combining the Kaplan surface mode approach for chiral fermions with added terms motivated by Eichten and Preskill suggests the possibility for a lattice regularization of the standard model which is finite, exactly gauge invariant, and only has physically desired states in its low energy spectrum. The conjectured scheme manifestly requires anomaly cancelation and explicitly contains baryon and lepton number violating terms.

hep-lat↗

arXiv1997

Getting Around the Nielsen-Ninomiya Theorem, towards the Rome Approach

The ``no-go'' theorem of Nielsen and Ninomiya has been the most tenacious obstacle against the construction of a chiral gauge theory with reasonable low energy spectrum, couplings and anomaly. In this paper we construct a model which supplements the usual (bilinear in the Fermi fields) lagrangian with quadrilinear fermionic terms. We show that in a certain region of the parameter space the difficulties of the ``no-go'' theorem may be overcome, and a ``renormalized'' perturbative strategy can be carried out, akin to the one followed in the Rome Approach (RA), whose counterterms are forced to be gauge invariant.

hep-lat↗

arXiv1997

Quark Masses and Mixing Angles

Inspired by the vector-like phenomenon of chiral gauge theories at short distances, we postulate that the $W^\pm$-gauge boson has a vector-like gauge coupling in the high-energy region, beside its purely right-handed gauge coupling observed in the low-energy region. It is discussed that the top quark acquires its mass via spontaneous symmetry breaking, while the $u,d,c,s,b$ quarks acquire their masses via explicit symmetry breakings. We discover four relationships between four inter-generation mixing angles and six quark masses by examining Dyson equations for quark self-energy functions. A preliminary analysis shows that the hierarchical pattern of quark masses is closely related to the hierarchical pattern of inter-generation mixing angles. In particular, the CP-violating phase is predicted to be approximately 79$^\circ$.

hep-ph↗

arXiv1996

A possible scaling region of chiral fermions on a lattice

We present the details of analyzing an $SU_L(2)\otimes U_R(1)$ chiral theory with multifermion couplings on a lattice. An existence of a possible scaling region in the phase space of multifermion couplings for defining the continuum limit of chiral fermions is advocated. In this scaling region, no spontaneous symmetry breaking occurs; the ``spectator'' fermion $ψ_R(x)$ is a free mode and decoupled; doublers are decoupled as massive Dirac fermions consistently with the $SU_L(2)\otimes U_R(1)$ chiral symmetry, whereas the normal mode of $ψ_L^i(x)$ is plausibly speculated to be chiral in the continuum limit. This is not in agreement with the general belief of the definite failure of theories so constructed.

hep-lat↗

arXiv1996

A Possible Lattice Chiral Gauge Theory

We analyze the dynamics of an $SU_L(2)\otimes U_R(1)$ chiral gauge theory on a lattice with a large multifermion coupling $1\ll g_2 < \infty$. It is shown that no spontaneous symmetry breaking occurs; the ``spectator'' fermion $ψ_R(x)$ is a free mode; doublers are decoupled as massive Dirac fermions consistently with the chiral gauge symmetry. Whether right-handed three-fermion states disappear and chiral fermions emerge in the low-energy limit are discussed. Provided right-handed three-fermion states disappear, we discuss the chiral gauge coupling, Ward identities, the gauge anomaly and anomalous $U_L(1)$ global current within the gauge-invariant prescription of renormalization of the gauge perturbation theory.

hep-lat↗

arXiv1996

Undoubled Chiral Fermions on a Lattice

We analyze the dynamics of an $SU_L(2)\otimes U_R(1)$ chiral theory on the lattice with a strong multifermion coupling. It is shown that no spontaneous symmetry breaking occurs; the ``spectator'' fermion $ψ_R$ is a free mode; doublers are decoupled as massive Dirac fermions consistently with the chiral symmetries. In 1+1 dimension, we show that the right-handed three-fermion state disappears at the threshold and an undoubled left-handed chiral fermion remains in the continuum limit.

hep-lat↗

arXiv1996

A Lattice Chiral Theory with Multifermion Couplings

Analyzing an $SU_L(2)\otimes U_R(1)$ chiral theory with multifermion couplings on a lattice, we find a possible region in the phase space of multifermion couplings, where no spontaneous symmetry breaking occurs, doublers are decoupled as massive Dirac fermions consistently with the $SU_L(2)\otimes U_R(1)$ chiral symmetry, the ``spectator'' fermion $ψ_R(x)$ is free mode, whereas the normal mode of $ψ^i_L(x)$ is plausibly speculated to be chiral in the continuum limit. This is not in agreement with the general belief of the definite failure of theories so constructed.

hep-lat↗

arXiv1996

The Emergence of a Heavy Quark Family on a Lattice

Within the framework of the ``Rome approach'' for a lattice chiral gauge theory, the four-quark interaction with flavour symmetry is included. We analyse spontaneous symmetry breaking and compute composite modes and their contributions to the ground state energy. As a result, it is shown that the emergence of a heavy quark family is the energetically favoured solution.

hep-lat↗

arXiv1995

A Lattice Chiral Gauge Theory with Multifermion Couplings

Analyzing an $SU_L(2)$-chiral gauge theory with external multifermion couplings, we find a possible scaling region where doublers decouple by acquiring chiral-invariant masses and $ψ_R$ is free mode owing to the $ψ_R$-shift-symmetry, the chiral continuum theory of $ψ^i_L$ can be defined. This is not in agreement with the general belief of the failure of theories so constructed .

hep-lat↗

arXiv1995

Quantum gravity, the Planck lattice and the Standard Model

A possible ground state of Quantum Gravity is Wheeler's ``space-time foam'', which can be modeled as a ``Planck-lattice'', a space-time cubic lattice of lattice constant $a_P\simeq 10^{33}$cm, the Planck length. I analyse the structure of the Standard Model defined on the Planck Lattice, in the light of the ``no-go'' theorem of Nielsen and Ninomiya, which requires an extension of the continuum model through Nambu-Jona Lasinio terms, quadrilinear in the Fermi-fields. As a result, a theory of masses (of both fermions and gauge bosons) is seen to emerge that, without Higgs excitations, agrees well with observations.

hep-th↗

arXiv1995

The Standard Model on a Planck Lattice: Mixing Angles vs Quark Masses

Proceeding in our research programme on the Standard Model (SM) on a Planck lattice (PLSM) we analyse the emergence of the quark masses through a ``superconducting'' mechanism of spontaneous violation of the chiral symmetry of the Standard Model. Due to the peculiar structure of the lattice coupling of the $W^\pm$ gauge bosons, we discover four new relationships between the angles of the mixing matrix and the (current) quark masses. In particular, we predict the CP-violating phase $δ_{13}\simeq 79^\circ$.

hep-ph↗

arXiv1994

The Spontaneous Breaking of Chiral Symmetry without Goldstone Bosons

Considering a self-interaction only of mirror fermions in the context of a lattice-regularized fermion field theory, we show that the system undergoes spontaneous breaking of chiral symmetry and mirror-fermion masses are generated. However, it is explicitly shown that there are no Goldstone bosons appearing together with this spontaneous symmetry breaking phenomenon, since Lorentz invariance, one of very general prerequisites of the Goldstone theorem, is violated. The result and its possible application are briefly discussed.

hep-lat↗

arXiv1994

The Mass Ratio Between Neutrinos and Charged Leptons

In the framework of the recently proposed electroweak theory on a Planck lattice, we are able to solve approximately the lattice Dyson equation for the fermion self-energy functions and show that the large difference of charged lepton and neutrino masses is caused by their very different gauge couplings. The predicted mass ratio ($10^{-5}\sim 10^{-6}$) between neutrinos and charged lepton is compatible with present experiments.

hep-lat↗