The European Physical Journal C最新文献

Chern–Simons theory in application to the quantum computing is actively developing at the present. However, most discussed are the questions of using materials with known parameters and building corresponding quantum gates and algorithms. In this paper we discuss opposite problem of finding Chern–Simons level k in the unknown material. For this purpose, we use the previously derived braiding rules for Chern–Simons (SU(2)_k) anyons. Using certain operations (turnarounds) on three anyons, one can measure probabilities of annihilation of pairs of anyons, which depend on the parameter of the theory. Therefore, Chern–Simons level k can be found from such an experiment. It is implied that anyons additionally possess certain properties which are required for topological quantum computations.

The method of variational bootstrapping, based on canonical variational completion, allows one to construct a Lagrangian for a physical theory depending on two sets of field variables, starting from a guess of the field equations for only one such set. This setup is particularly appealing for the construction of modified theories of gravity, since one can take lessons from GR for an “educated guess” of the metric field equations; the field equations for the other fields are then fixed by the obtained Lagrangian (up to terms that are completely independent from the metric tensor). In the present paper, we apply variational bootstrapping to determine metric-affine models which are, in a variational sense, closest to the (Lambda )CDM model of cosmology. Starting from an “educated guess” that formally resembles the Einstein field equations with a cosmological “constant” (actually, a scalar function built from the metric and the connection) and a dark matter term, the method then allows to find “corrected” metric equations and to “bootstrap” the connection field equations. Lagrangians obtained via this method, though imposing some restricting criteria, still encompass a wide variety of metric-affine models. In particular, they allow for a subclass of quadratic metric-affine theories restricted to linear terms in the curvature tensor.

The search for Dark Matter (DM) at colliders is primarily pursued via the detection of missing energy in particular final states. These searches are based on the production and decay processes where final states include DM particles and at least one Standard Model (SM) particle. DM will then reveal itself as missing energy. An alternative form to get a hint of a dark sector is via loop contribution to SM processes. In this case, it is not even relevant if the new particles have their origin in the dark sector of the model. In this work we discuss the impact of an arbitrary number of coloured scalars with (Z_2)-odd parity in single Higgs and double Higgs production at the Large Hadron Collider (LHC), and we show their complementarity. We determine the range of variation of the corrections relative to the SM for an arbitrary number of coloured scalars n. We discuss the cases (n=1) and (n=2) for a specific model in more detail, which includes direct searches at the LHC. We also find that the electroweak observable T parameter imposes significant restrictions on the difference of the heavy coloured scalar masses.

This paper investigates the characteristics and stability of nonrotating BTZ-ModMax thin-shell wormholes, emphasizing the interaction between spacetime structure and black hole parameters. The locality of the event horizon is substantially affected by the ModMax parameter (xi ) and the horizon shifting inward by increasing the ModMax parameter. We examine that enhancing the charge of a black hole results in an extension of the horizon radius which shows the intricate interplay between charge and geometry. Here, we use different types of matter distribution characterized by distinct equations of state. It is noted that the thin-shell wormhole configurations containing quintessence-like matter have more stability, whereas configurations with phantom energy demonstrate unstable behavior. Our stability analysis reveals that thin-shell wormholes exhibit increased stability with higher values of charge, whereas larger cosmological constants diminish stability regions. Moreover, the generalized Chaplygin gas results in unstable configurations, underscoring the significance of the matter type in ascertaining wormhole stability. These findings deepen our comprehension of thin-shell wormholes and create new possibilities for future inquiry in theoretical physics.

In this paper, we consider the effect of interactions on the local, average polarization of a quantum plasma of massless fermion particles characterized by vector, axial, and helical quantum numbers. Due to the helical and axial vortical effects, perturbations in the vector charge in a rotating plasma can lead to chiral and helical charge transfer along the direction of the vorticity vector. At the same time, interactions between the plasma constituents lead to the dissipation of the helical charge through helicity-violating pair annihilation (HVPA) processes and of the axial charge through the axial anomaly. We will discuss separately a QED-like plasma, in which we ignore background electromagnetic fields and thus the axial charge is approximately conserved, as well as a QCD-like plasma, where instanton effects lead to the violation of the axial charge conservation, even in the absence of background chromomagnetic fields. The non-conservation of helicity and chirality leads to a gapping of the Helical, Axial, and mixed Axial-Helical vortical waves that prevents their infrared modes from propagating. On the other hand, usual dissipative effects, such as charge diffusion, lead to significant damping of ultraviolet modes. We end this paper with a discussion of the regimes where these vortical waves may propagate.

The transverse momentum ((p_{textrm{T}})) differential production cross section of the promptly produced charm-strange baryon (mathrm {Xi _{c}^{0}}) (and its charge conjugate (overline{mathrm {Xi _{c}^{0}}})) is measured at midrapidity via its hadronic decay into (mathrm{pi ^{+}}Xi ^{-}) in p–Pb collisions at a centre-of-mass energy per nucleon–nucleon collision (sqrt{s_{textrm{NN}}}~=~5.02) TeV with the ALICE detector at the LHC. The (mathrm {Xi _{c}^{0}}) nuclear modification factor ((R_{textrm{pPb}})), calculated from the cross sections in pp and p–Pb collisions, is presented and compared with the (R_{textrm{pPb}}) of (mathrm {Lambda _{c}^{+}}) baryons. The ratios between the (p_{textrm{T}})-differential production cross section of (mathrm {Xi _{c}^{0}}) baryons and those of (mathrm {D^0}) mesons and (mathrm {Lambda _{c}^{+}}) baryons are also reported and compared with results at forward and backward rapidity from the LHCb Collaboration. The measurements of the production cross section of prompt (Xi ^0_textrm{c}) baryons are compared with a model based on perturbative QCD calculations of charm-quark production cross sections, which includes only cold nuclear matter effects in p–Pb collisions, and underestimates the measurement by a factor of about 50. This discrepancy is reduced when the data is compared with a model that includes string formation beyond leading-colour approximation or in which hadronisation is implemented via quark coalescence. The (p_{textrm{T}})-integrated cross section of prompt (Xi ^0_textrm{c})-baryon production at midrapidity extrapolated down to (p_{textrm{T}}) = 0 is also reported. These measurements offer insights and constraints for theoretical calculations of the hadronisation process. Additionally, they provide inputs for the calculation of the charm production cross section in p–Pb collisions at midrapidity.

We show that the ((1+3))-dimensional ‘superboost’ operators, proposed in Dragan and Ekert’s most recent work on superluminal reference frames (Dragan et al. in Class Quantum Gravity 40(2): 025013, 2023), are simply the canonical Lorentz boosts, expressed in nonstandard notation. Their ((1+3))-dimensional ‘superflip’, which is claimed to interchange time and space dimensions for a superluminal observer, travelling with infinite speed, is equivalent to applying the identity operator together with an arbitrary relabeling. Physically, it corresponds to staying put within the canonical rest frame, then renaming space as ‘time’ and time as ‘space’. We conclude that their extension of the ‘quantum principle of relativity’, proposed in earlier work on ((1+1))-dimensional spacetimes (Dragan and Ekert in New J Phys 22(3): 033038, 2020), to ordinary Minkowski space, is simply Einstein’s principle of relativity, proposed in 1905.

In this work, we analyze various phenomena influenced by the gravitational field in a bumblebee gravity solution, with a particular emphasis on a traversable wormhole for massless particle modes. Specifically, we calculate the index of refraction, group velocity, time delay, modified distances, and interparticle potential, demonstrating the possibility of photon-photon interactions due to the wormhole geometry. For the latter aspect, we also extend the analysis to massive particle modes, resulting in a “combination” of modified Yukawa- and Coulomb-like potentials. These calculations are shown to be dependent on the wormhole’s parameters, particularly the wormhole throat. In addition to these analyses, the Hawking temperature is derived using the trapping horizon method, yielding negative values. Furthermore, we derive the thermodynamic properties of photon-like modes by incorporating the modified dispersion relation arising from the wormhole geometry, focusing on non-interacting particle modes. Remarkably, all calculations are conducted in a fully analytical framework.

We construct and analyse wormhole solutions in quantised space-time. The field equations are constructed from the deformed wormhole metric in the proper reference frame using tetrads. The spatial geometry of the wormhole is analysed in kappa space-time. Further, modifications to the conditions that ensure traversibility of the wormhole are studied and it is found that the necessity of the exotic matter persists in the non-commutative case as in the commutative space-time. Casimir energy is considered a possible source for exotic matter and it is shown that the time to pass through the wormhole as well as the amount of exotic matter required to create the wormhole reduce due to non-commutativity of space-time.