arXiv subjects

J. H. Muñoz

Publications and source records attributed to J. H. Muñoz.

10 recordsLinked to original sources

arXiv2023

Some remarks on projectile motion with a linear resistance force

In this article we revisit the projectile motion assuming a retarding force proportional to the velocity, $\vec{F_r} = -mk\vec{V}$. We obtain an analytical expression for the set of maxima of the trajectories, in Cartesian coordinates, without using the Lambert $W$ function. Also, we investigate the effect of the parameter $k$ on the radial distance of the projectile showing that the radial distance oscillates from a certain critical launch angle and find an approximate expression for it. In our analysis, we consider the impact of the parameter $k$ in the kinetic energy, the potential energy, the total energy and the rate of energy loss, and in the phase space. Our results can be included in an intermediate-level classical mechanics course.

physics.ed-ph↗

arXiv2023

$B$ meson anomalies within the triplet vector boson model to the light of recent measurements from LHCb

The triplet vector boson (TVB) is a simplified new physics model involving massive vector bosons transforming as a weak triplet vector. Such a model has been proposed as a combined explanation of the anomalous $b \to sμ^+μ^-$ and $b \to c τ\barν_τ$ data (the so-called $B$ meson anomalies). In this work, we carry out an updated view of the TVB model by incorporating the most recent 2022 and 2023 LHCb measurements on the lepton flavor universality ratios $R(D^{(\ast)}) = {\rm BR}(B \to D^{(\ast)}τ\barν_τ)/{\rm BR}(B \to D^{(\ast)}\ell^\prime \barν_{\ell^\prime})$, $R(Λ_c) = {\rm BR}(Λ_b \to Λ_cτ\barν_τ)/{\rm BR}(Λ_b \to Λ_cμ\barν_μ)$, and $R_{K^{(\ast)}} = {\rm BR}(B \to K^{(\ast)}μ^+μ^-)/{\rm BR}(B \to K^{(\ast)}e^+e^-)$. We perform a global fit to explore the allowed parameter space by the new data and all relevant low-energy flavor observables. Our results are confronted with the recent high-mass dilepton searches at the Large Hadron Collider (LHC). We find that for a heavy TVB mass of 1 TeV a common explanation of the $B$ meson anomalies is possible for all data with the recent LHCb measurements on $R(D^{(\ast)})$, in consistency with LHC constraints. However, this framework is in strong tension with LHC bounds when one considers all data along with the world average values (BABAR, Belle, and LHCb) on $R(D^{(\ast)})$. Future measurements will be required in order to clarify such a situation. In the end, the implications of our phenomenological analysis of the TVB model to some known flavor parametrizations are also discussed.

hep-ph↗

arXiv2022

Singlet vector leptoquark model facing recent LHCb and BABAR measurements

Very recently the LHCb experiment released the first measurement of the ratio $R(Λ_c) = {\rm BR}(Λ_b \to Λ_cτ\barν_τ)/{\rm BR}(Λ_b \to Λ_cμ\barν_μ)$. Moreover, the BABAR experiment reported a new result of the leptonic decay ratio of Upsilon meson $Υ(3S)$, namely, $R_{Υ(3S)} = {\rm BR}(Υ(3S) \to τ^+τ^-)/{\rm BR}(Υ(3S) \to μ^+μ^-)$. Both measurements are below their corresponding Standard Model predictions (deficit), deviating by $\sim 1.1σ$ and $\sim 1.8σ$, respectively. Moreover, the LHCb recently presented the first search of the lepton flavor violating decay $B^0 \to K^{\ast 0}μ^\pmτ^\mp$. Motivated by these new data, in this work we study their impact on the phenomenology of the singlet vector leptoquark ($U_1$) model addressing the hints of lepton flavor universality violation in the semileptonic decays of $B$ mesons ($B$ meson anomalies), by carrying out a global fit analysis. In general, we found that a minimal version of the $U_1$ model with a mass of 1.8 TeV can successfully explain the $B$ meson anomalies, while being compatible with all other flavor observables and LHC bounds. Interestingly, our study shows that the new observables $R(Λ_c)$ and $R_{Υ(3S)}$ generate strong tension, leading to non-trivial effects on the global fit. Future improvements at the LHCb and Belle II experiments would help to understand their complementarity. Moreover, we also analyze the impact of the expected sensitivity on flavor observables at Belle II to provide a further test of the $U_1$ model. Finally, we study the minimal assumptions under which the $U_1$ model could, in addition, provide a combined explanation of the anomalous magnetic moment of the muon.

hep-ph↗

arXiv2021

Extra gauge bosons and lepton flavor universality violation in $Υ$ and $B$ meson decays

Lepton flavor universality can be tested through the ratio of semileptonic $B$ meson decays and leptonic $Υ$ meson decays, with $Υ\equiv Υ(nS)$ ($n=1,2,3$). For the charged-current transitions $b \to cτ\barν_τ$, discrepancies between the experiment and the Standard Model (SM) have been observed in recent years by different flavor facilities such as BABAR, Belle, and LHCb. While for the neutral-current transitions $b \bar{b} \to τ\barτ$, the BABAR experiment reported recently a new measurement of leptonic decay ratio $R_{Υ(3S)} = {\rm BR}(Υ(3S) \to τ^+τ^-)/{\rm BR}(Υ(3S) \to μ^+μ^-)$, showing an agreement with the SM at the $1.8 σ$ level. In light of this new BABAR result and regarding the connection between new physics (NP) interpretations to the charged-current $b \to c τ\barν_τ$ anomalies and neutral-current $b \bar{b} \to τ\barτ$ processes, in this study, we revisit the NP consequences of this measurement within a simplified model with extra massive gauge bosons that coupled predominantly to left-handed leptons of the third-generation. We show that the BABAR measurement of $R_{Υ(3S)}$ cannot easily be accommodated (within its experimental $1σ$ range) together with the other $b \to cτ\barν_τ$ data, hinting toward a new anomalous observable.

hep-ph↗

arXiv2020

Analysing the charged scalar boson contribution to the charged-current $B$ meson anomalies

Experimental measurements collected by the BABAR, Belle, and LHCb experiments on different observables associated with the semileptonic transition $b \to c τ\barν_τ$, indicate the existence of disagreement respect with the Standard Model predictions. We analyse the charged scalar boson contributions to these charged-current $B$ meson anomalies within the framework of two Higgs doublet model with the most general Yukawa couplings to quarks and leptons from the third generation, involving left-handed and right-handed (sterile) neutrinos. We perform a phenomenological study of the Yukawa couplings parameter space that accommodates these anomalies. We consider the most recent data from HFLAV world-average and Belle combination, and the upper limits ${\rm BR}(B_c^- \to τ^- \barν_τ) < 30\%$ and $10\%$. In addition, we include in our study the prospect measurements on $R(D^{(\ast)})$ that the Belle II experiment could achieve and explore, for the first time, the future implications for the corresponding charged scalar Yukawa couplings. This analysis updates the existing literature and includes new important observables. Our results show that current experimental $b\rightarrow c τ\barν_τ$ data and Belle II projection favor the interpretation of a charged scalar boson interacting with right-handed neutrinos. Furthermore, as a side analysis regarding the charged scalar boson interpretation, we revisit the relation between $R(D^\ast)$ and ${\rm BR}(B_c^- \to τ^- \barν_τ)$ by investigating whether the claim that pseudoscalar new physics interpretations of $R(D^{\ast})$ are implausible due to the $B_c$ lifetime is still valid, to the light of the recent data and Belle II prospects on $R(D^{\ast})$. Lastly, we reexamine addressing the $R(D^{(\ast)})$ anomalies in the context of the 2HDM of Type II.

hep-ph↗

arXiv2020

Two blocks connected by a string with variable tension: A dynamic case

In this paper, the dynamic case of a system made up of two blocks connected by a string over a smooth pulley is revisited. One mass lies on a horizontal surface without friction, and the other mass has a vertical displacement. The motion equation is obtained and its solution is determined using the Mathematica package. Also, an experimental montage for this system is made and experimental data for the vertical position $y$ in function of the time $t$ are obtained using a Data Acquisition System and the Tracker video analysis. The relation $y$ vs $t$ can be represented by a polynomial of degree six. An average relative error of 3.61 (10.14) % is obtained between the theoretical results acquired with Mathematica and the data taken from the Tracker (Data Acquisition System).

physics.ed-ph↗

arXiv2019

Symmetry in the system conformed by two blocks connected by a string with variable tension

In this paper we review the system made up by two blocks connected by a string over a smooth pulley with variable tension. One block lies on an horizontal surface and the another block is hanging vertically. We carry out a complete and systematic analysis for the tension of the string as function of the angle and the horizontal distance x, at static equilibrium. We find a simmetry-like that corresponds to two different confifigurations with the same tension and obtain the relationship that must satisfy two angles or two horizontal distances to obtain equal tension.

physics.ed-ph↗

arXiv2011

Useful ratios between two-body nonleptonic and semileptonic decays of B mesons

We compute important ratios between decay widths of some exclusive two-body nonleptonic and semileptonic B decays, which could be test of factorization hy- pothesis. We also present a summary of the expressions of the decay widths and differential decay rates of these decays, at tree level, including l = 0 (ground state), l = 1 (orbitally excited) and n = 2 (radially excited) mesons in the fi- nal state. From a general point of view, we consider eight transitions, namely H \rightarrow P, V, S, A, A, T, P (2S), V (2S). Our analysis is carried out assuming factorization hypothesis and using the WSB, ISGW and CLFA quark models.

hep-ph↗

arXiv2008

Remarks about decay widths of two-body nonleptonic and semileptonic $B$ decays

We present a brief discussion about expressions of decay widths of exclusive nonleptonic and semileptonic B decays at tree level including $l=0$ and $l=1$ mesons in final state. Our analysis is carried out assuming factorization hypothesis and using parametrizations of hadronic matrix elements given in WSB and ISGW quark models. Special interest is focused on dynamics of these processes and several important ratios between decay widths to determine form factors and decay constants are given.

hep-ph↗

arXiv1999

Semileptonic and non-leptonic B_c decays

We make predictions for the exclusive semileptonic and the non-leptonic decay widths of the B_c meson. We evaluate the B_c semileptonic form factors for different decay channels in a relativistic model, and use factorization to obtain the non-leptonic decay widths.

hep-ph↗