arXiv subjects

M. Schwetz

Publications and source records attributed to M. Schwetz.

10 recordsLinked to original sources

arXiv2023

Three-qubit Deutsch-Jozsa in measurement-based quantum computing

Measurement-based quantum computing (MBQC), an alternate paradigm for formulating quantum algorithms, can lead to potentially more flexible and efficient implementations as well as to theoretical insights on the role of entanglement in a quantum algorithm. Using the graph-theoretical ZX-calculus, we describe and apply a general scheme for reformulating quantum circuits as MBQC implementations. After illustrating the method using the two-qubit Deutsch-Jozsa algorithm, we derive a ZX graph-diagram that encodes a general MBQC implementation for the three-qubit Deutsch-Jozsa algorithm. This graph describes an 11-qubit cluster state on which single-qubit measurements are used to execute the algorithm. Particular sets of choices of the axes for the measurements can be used to implement any realization of the oracle. In addition, we derive an equivalent lattice cluster state for the algorithm.

quant-ph↗

arXiv2002

Strongly coupled N=1 SYM theory on the lattice

We propose a strong coupling expansion as a possible tool to obtain qualitative and quantitative informations about N=1 SYM theory. We point out the existence of a mapping between strongly coupled lattice N=1 SYM theory and a generalized SO(4) antiferromagnetic spin system.

hep-lat↗

arXiv2000

Anomaly Matching in Gauge Theories at Finite Matter Density

We investigate the application of 't Hooft's anomaly matching conditions to gauge theories at finite matter density. We show that the matching conditions constrain the low-energy quasiparticle spectrum associated with possible realizations of global symmetries.

hep-ph↗

arXiv1998

The Spectrum and Effective Action of SUSY Gluodynamics

We study the low-energy spectrum of SUSY gluodynamics using the generating functional for Green's functions of composite fields. Two dual formulations of the generating functional approach are given. Masses of the bound states are calculated and mixing patterns are discussed. Mass splittings of pure gluonic states, in the case when supersymmetry is softly broken, are consistent with predictions of conventional Yang-Mills theory. The results can be tested in lattice simulations of the SUSY Yang-Mills model.

hep-ph↗

arXiv1998

The Spectrum of Softly Broken N=1 Supersymmetric Yang-Mills Theory

We study the spectrum of the softly broken generalized Veneziano-Yankielowicz effective action for N=1 SUSY Yang-Mills theory. Two dual formulations of the effective action are given. The spurion method is used for the soft SUSY breaking. Masses of the bound states are calculated and mixing patterns are discussed. Mass splittings of pure gluonic states are consistent with predictions of conventional Yang-Mills theory. The results can be tested in lattice simulations of the SUSY Yang-Mills model.

hep-th↗

arXiv1997

On the Effective Action of N=1 Supersymmetric Yang-Mills Theory

We propose a generalization of the Veneziano-Yankielowicz effective low-energy action for N=1 SUSY Yang-Mills theory which includes composite operators interpolating pure gluonic bound states. The chiral supermultiplet of anomalies is embedded in a larger three-form multiplet and an extra term in the effective action is introduced. The mass spectrum and mixing of the lowest-spin bound states are studied within the effective Lagrangian approach. The physical mass eigenstates form two multiplets, each containing a scalar, pseudoscalar and Weyl fermion. The multiplet containing the states which are most closely related to glueballs is the lighter one.

hep-th↗

arXiv1996

QCD at Large $θ$ Angle and Axion Cosmology

We use the chiral Lagrangian to investigate the global properties of the $N$-flavor QCD vacuum as a function of the $θ$ parameter. In the case of exact quark degeneracy we find evidence for first order phase transitions at $θ= π\cdot ({\rm odd~ integer})$. The first order transitions are smoothed by quark mass splittings, although interesting effects remain at realistic quark masses. We emphasize the role of the $η'$ condensate in our analysis. Finally, we discuss the implications of our results on the internal hadronic structure of axion domain walls and axion cosmology.

hep-ph↗

arXiv1996

Phase Transitions in Softly Broken N=2 SQCD at Non-zero Theta Angle

We investigate the behavior of softly broken $N=2$ SQCD at non-zero bare theta angle $θ_0$, using superfield spurions to implement the SUSY breaking. We find a first-order phase transition as $θ_0$ is varied from zero to $2 π$, in agreement with a prediction of `t Hooft. The low-energy theta angle $θ_{eff}$, which determines the effective charges of dyonic excitations, has a complicated dependence on $θ_0$ and breaking parameters.

hep-th↗

arXiv1996

Chiral Perturbation Theory, Large-N_c and the eta' Mass

Using chiral perturbation theory and the large-$N_c$ expansion, we obtain expressions for the $η'$ mass and $η- η'$ mixing in terms of low-energy chiral Lagrangian parameters. This is accomplished through an intermediate step of `matching' the topological susceptibility in the large-$N_c$ and chiral Lagrangian descriptions. By inserting the values of well-measured parameters we obtain predictions involving the the second order parameters $L_6,L_7$ and $L_8$. The prediction for $L_6$ is quite restrictive even after allowing for $1/ N_c$ corrections.

hep-ph↗

arXiv1996

Topological Charge and $U(1)_A$ Symmetry in the High Temperature Phase of QCD

We discuss the global symmetries of the high temperature phase of QCD with $N_f$ massless quarks. We show that the $U(N_f) \times U(N_f)$ symmetries are only violated by operators of dimension $\geq 3 N_f$. For $N_f > 2$ this implies that the thermal two-point correlation functions of the $η'$ and $π^a$'s are identical. We discuss the implications of this for the chiral phase transition at finite temperature.

hep-ph↗