International Journal of Modern Physics A

We propose a neutrino lepton collider where the neutrino beam is generated from TeV scale muon decays. Such a device would allow for a precise measurement of the W mass based on single W production $\nu l\to {\mathrm{\text{W}}}^{(\ast )}$. Although it is challenging to achieve high instantaneous luminosity with such a collider, we find that a total luminosity of 0.1${\mathrm{\text{fb}}}^{-1}$ can already yield competitive physics results. In addition to a W mass measurement, a rich variety of physics goals could be achieved with such a collider, including W boson precision measurements, heavy leptophilic gauge boson searches and anomalous $\mathrm{\text{Z}}\nu \nu$ coupling searches. A neutrino lepton collider is both a novel idea in itself, and may also be a useful intermediate step, with less muon cooling required, towards the muon–muon collider already being pursued by the energy frontier community. A neutrino neutrino or neutrino proton collider may also be interesting future options for the high energy frontier.

In top–bottom seesaw and topflavor model, there may exist extra Higgs bosons and vector-like fermions, and we have examined the W-mass anomaly reported by CDF II in these frames. We found that the CDF II W-boson mass data constrains the parameter $r_t$ and $z_t$ strictly in the two models, respectively, while the constraints on other parameters such as $m_H$, $m_{\chi }$ are quite weak. Therefore, we conclude that in the two models, the W-mass increment is sensitive to the extra fermions, but not the extra scalars. In topFlavor model, we also consider the W-mass increment induced by the mass mixing of the light and the heavy gauge bosons and the contribution is not too large and the constraints on the parameters $x$ and $y$ are weak.

The Quantum Chromo Dynamics (QCD), with its two main properties of confinement and asymptotic freedom, is considered as the fundamental theory of the strong interaction from which the phenomenology of string model and hadronic bag models can be derived as particular cases. In QCD, besides quark masses, there is only one parameter, the renormalization scale parameter $\mathrm{\Lambda }$, which comes into play. In nonperturbative models, like string model and bag models, the string constant $\sigma$, the hadronic bag surface tension $\mathrm{\Sigma }$ and the concept of the hadronic bag pressure ${ℬ}$ emerge naturally. Since these parameters characterize the same color confining force, this explains the existence of simple mathematical relationships that connect them. Although in most applications of the MIT bag model, considering ${ℬ}$ with its phenomenologically determined value as a constant does not generate any inconsistency, however, there are some indications that ${ℬ}$ is not a universal constant. The concept of hadronic bag pressure ${ℬ}$ as a parameter was introduced long before, and we plan in this work to extrapolate the concept of ${ℬ}$ to become a full-fledged thermodynamic variable and to explore the consequences of its variability in the context of our colorless MIT bag model. To achieve this, we carry out a detailed thermodynamic study based on the three variables $(T,V,{ℬ})$ using an improved ${\mathcal{ℒ}}_{m,n}$-method and considering the hadronic bag pressure ${ℬ}$ as a thermodynamic variable like the temperature $T$ and volume $V$. The findings in the small ${ℬ}$ region, in themselves, are very unexpected and exciting that essentially concern the abnormal behavior of the order parameter ${\mathscr{H}}(T,V,{ℬ})$. This shows that, from an experimental point of view, a low value of the hadronic bag pressure ${ℬ}$ would have dramatic consequences. Thus, it is argued that the abnormal behavior observed in the order parameter ${\mathscr{H}}(T,V,{ℬ})$ well reflects the appearance of the mixed state at low temperature before the deconfining process. We also indicate how this result might be avoided by imposing a lower bound on the hadronic bag pressure: ${ℬ}\ge {{ℬ}}_{\mathrm{\text{min}}}$. A detailed study of the global properties of the order parameter ${\mathscr{H}}(T,V,{ℬ})$ as function on the three variables is given, and as an illustration of our ideas we construct three different criteria from which we extract the lower bound of the hadronic bag pressure ${{ℬ}}_{\mathrm{\text{min}}}$. We succeeded to show that the physically genuine colorless deconfining phase transition is feasible only if the thermodynamic lower bound is taken as ${{ℬ}}_{\mathrm{\text{min}}}^{1∕4}\simeq 56$MeV. As a consequence, the corresponding lower bound of the hadronic bag surface tension is ${\mathrm{\Sigma }}_{\mathrm{\text{min}}}^{1∕3}\simeq 47.77$MeV. Our results are consistent with each other, and seem to corroborate the results obtained by other approaches, such as the thermodynamic model of chromo-magnetism. We focus not only on certain technical details, but also on physical understanding and interpretation. The results are relevant for the parton phenomenology of stars and for URHIC experiments. We review some of the underlying physics and discuss outstanding questions regarding this variability.

We revisit the issue that the Noether current associated with a local scale symmetry, or equivalently the Weyl symmetry, identically vanishes. Based on only the second Noether theorem for a local symmetry, we prove that the Noether current associated with the Weyl symmetry is in general vanishing in any Weyl invariant gravitational theories in four-dimensional Riemannian geometry. We also clarify the reason: The Weyl transformation is nondynamical in the sense that it does not contain the derivative term of the transformation parameter as opposed to the conventional gauge transformation.

In this work, considering anisotropic and homogeneous Bianchi type-V universe we investigated Kaniadakis holographic dark energy (KHDE). It is demonstrated that the equation of state (EoS) parameter has a transition from the quintessence era to the phantom era for the chosen model. Additionally, in the late time of the universe, EoS parameter behaves like a cosmological constant ($\mathrm{\Lambda }$) with an IR (Infrared) cut-off apparent horizon in case of a particular form of deceleration parameter. We reconstructed correspondence between the KHDE and tachyon, quintessence and k-essence scalar fields. Also, our numerical solutions have been shown in graphs for EoS parameter and scalar fields.

Guided by Pippard superconductivity, we incorporate the Seiberg–Witten map in the classical London theory of Type-I superconductors when an external magnetic field is applied. After defining the noncommutative Maxwell potentials, we derive the London equation for the supercurrent as a function of the noncommutative parameter, up to second order in gauge fields expansions. Keeping track of the effects of noncommutative gauge fields, we argue that noncommutative magnetic field effects can be cast in the London penetration length similar to nonlocal Pippard superconductivity. Also, we show that the flux quantization remains consistent relative to the commutative case. Our effective London penetration length reduces to the standard one in the commutative limit. These results allow us to argue that the framework of noncommutative electrodynamics can give some insights into the anisotropic and nonlocal structure of superconductivity and Condensed Matter Systems, perhaps out of the ultra-microscopic scale regime.

The random forest method is used for the first time to provide results for some heavy meson spectra, such as $b\bar{b}$ mesons. The performance of our model in predicting the mass spectra of $b\bar{b}$ mesons from 1S to 6S states is investigated. The predictions are in a good accordance with the latest experimental data and other theoretical approaches.

Study of the mechanism of heavy quarkonia production is a powerful tool for a better understanding of the dynamics of strong interactions and probably to search for new physics. It is well-known that the fragmentation mechanism is dominant for heavy quarkonia production and forms the nonperturbative aspect of hadron production. Since the main contribution of $J∕\psi$ production in high energy processes results from the gluon fragmentation, through this work, we study the fragmentation mechanism of gluon into S-wave vector heavy charmonium $J∕\psi$ at lowest order perturbative QCD and extend our work to the noncommutative standard model. To investigate the effects of space–time noncommutativity, we employ the Seiberg–Witten maps. Our results show that the noncommutative effects are considerable, specifically when the gluon transverse momentum is small; $p_T<30$GeV.

We construct a nontopological string solution for a supersymmetric gauge theory with $SU(2)\times U(1)$ gauge symmetry which is spontaneously broken to $U(1)$ by developing the vacuum expectation value of two doublet Higgses. It is a supersymmetric extension of the electroweak string while supersymmetry is unbroken. We discuss the classical stability of the nontopological string by perturbations. We show that the classical stability is determined only by two parameters, and that the allowed region becomes essentially the same as in the electroweak string.

In this paper, we introduce matrix operator algebra involving a universal curvature constant and using the Dunkl derivative. Consequently, the Dirac equation can be written without spin connections. Iterating the Dirac equation gives the Klein–Gordon equation in its canonical form without first-order Dunkl derivatives. This leads to a new form for the static metric based on the Dunkl operator in curved space.

Old folklore says that there is no nontrivial renormalization group fixed point with $U(1)$ gauge symmetry in four dimensions, but it can be circumvented by the existence of magnetic monopoles. We propose to construct (potentially infinitely many) novel types of field theories with $U(1)$ gauge symmetry by gauging $U(1)\times U(1)$ global symmetry electrically and magnetically. If the construction is consistent, the resulting theory will most likely possess a nontrivial renormalization group fixed point for the $U(1)$ gauge coupling constant and it will be a nontrivial conformal field theory without the $U(1)\times U(1)$ global symmetry in the infrared upon tunings of other relevant deformations. If the construction is CP-violating, a renormalization of the $\theta$-parameter is accompanied.

In this paper, we use the concept of conformable fractional derivative to study the nonrelativistic radial Schrödinger equation. We suggest an extended version of the Cornell potential as the quark–antiquark interaction of light and heavy mesons. We generalize the asymptotic iteration method to the fractional domain. The latter is used to calculate the energy eigenvalues, as well as the effect of the fractional order $\nu$ on energy spectra. To test the applicability of our model, we use the obtained results to reproduce the mass spectra of some light and heavy mesons such as $b\bar{b}$, $c\bar{c}$, $c\bar{s}$, $\bar{b}c$, $b\bar{q}$ and $b\bar{s}$ quarks. The mass spectra are obtained at different values of the fractional order parameter $\nu$ and were compared with experimental results and other relevant theoretical works. Using the wave function, we calculated the decay constants for heavy-light $D^0$, $D^{+}$, $D_s^{+}$, $B^{-}$, ${\bar{B}}^0$ and ${\bar{B}}_s^0$ mesons. Our results are found to be in good agreement with the experimental data, and improved in comparison with other theoretical previsions.