HEP Phenomenology·hep-ph
25 papers—21 primary·4 cross-listed·reconstructed*
The Cabibbo Angle Anomaly, an apparent deficit in first-row CKM unitarity, can be addressed by leptophilic Standard Model extensions that generate new contributions to the Fermi constant and affect the determination of the CKM element . We focus on simplified models with this property, including the Standard Model extended by vectorlike leptons, by the singly charged scalar singlet, or by a leptophilic boson.
Aftab Ahmad🇵🇰 · Ali Murad🇵🇰
We study the dynamical chiral symmetry breaking/restoration for the various numbers of light quarks flavors and colors , using the Nambu-Jona-Lasinio (NJL) model of quarks, dressed with a color-flavor dependence of effective coupling. Initially, we set , and varying the number of colors , we find that the dynamical chiral symmetry is broken when exceeds to its critical value . Secondly, we take , and varying , we observed that the dynamical chiral symmetry is restored when reaches to its critical value . The strong interplay observed between and , i.e., anti-screens the strong interactions by strengthening the dynamical mass and quark-antiquark condensate, while screens the strong interaction by suppressing both the parameters. We further sketch the quantum chromodynamics (QCD) phase diagram at finite temperature and quark chemical potential for various and . At finite and , we observed that the critical number of colors enhances while the critical number of flavors suppresses as and increases. Of course, the parameters and produce the screening effect. Consequently, the critical temperature , and co-ordinates of the critical endpoint in the QCD phase diagram enhances as increases while suppresses when increases. Our findings agree with the Lattice QCD and Schwinger-Dyson equations predictions.
Yeong Gyun Kim🇰🇷 · Kang Young Lee🇰🇷 · Jungil Lee🇰🇷 · Soo-hyeon Nam🇰🇷
We discuss vacuum structure and vacuum stability in classically scale-invariant renormalizable models with a scalar dark matter multiplet of global O(N) symmetry together with an electroweak singlet scalar mediator. Our conformally invariant scalar potential generates the electroweak symmetry breaking via the Coleman-Weinberg mechanism, and the new scalar singlet mediator acquires its mass through radiative corrections of the scalar dark matters as well as of the standard model particles. Taking into account the present collider bounds, we find the region of parameter space where the scalar potential is stable and all the massless couplings are perturbative up to the Planck scale. With the obtained parameter sets satisfying the vacuum stability condition, we present the allowed region of new physics parameters satisfying the recent measurement of relic abundance, and predict the elastic scattering cross section of the new scalar multiplet into target nuclei for a direct detection of the dark matter. We also discuss the collider signatures and future discovery potentials of the new scalars.
Takaaki Nomura🇨🇳 · Hiroshi Okada🇰🇷
We propose a supersymmetric radiative seesaw model with modular symmetry. Thanks to contributions of supersymmetric partners to one-loop diagrams generating neutrino masses, we successfully fit neutrino data and obtain predictions in case of normal hierarchy in a minimal framework that would not be realized in a non-supersymmetric model. We show a several predictive figures and demonstrate a best fit benchmark point through
G.I. Lykasov🇷🇺 · A.I. Malakhov🇷🇺 · A.A. Zaitsev🇷🇺
The inclusive spectra of pions and kaons produced in collisions as functions of their transverse momentum at mid-rapidity are calculated within the self-similarity approach. A satisfactory description of NA61/SHINE data on these spectra and the ratio of to meson production cross sections in collisions as a function of are presented. The similarity of these observables to the ones for collisions at mid-rapidity and in the wide range of initial energies is illustrated.
Zhi-Wei Lu🇨🇳 · Qian Zhao🇨🇳 · Feng Wan🇨🇳 · Bo-Chao Liu🇨🇳 · Yong-Sheng Huang🇨🇳 · Zhong-Feng Xu🇨🇳 · Jian-Xing Li🇨🇳
Generation of arbitrarily spin polarized muon pairs is investigated via polarized collision. We calculate the fully spin-resolved cross section and utilize the Monte Carlo method of binary collision to describe the production and polarization processes of muon pairs. We find that, due to the dependence of mixed helicities on the scattering angle, arbitrarily polarized muon pairs with both of the longitudinal and transverse spin components can be produced. The collision of tightly collimated electron and positron beams with highly longitudinal polarization and nC charge can generate about muon pairs with longitudinal polarization and about muon pairs with transverse polarization. The compact high-flux muon source could be implemented through the next-generation laser-plasma linear collider, and would be essential to facilitate the investigation of fundamental physics and the measurement technology in broad areas.
Maria Archidiacono🇮🇹 · Stefano Gariazzo🇮🇹
The presence of light sterile neutrinos is one of the unanswered questions of particle physics. The cosmological counterpart is represented by dark radiation, i.e.\ any form of radiation present in the early Universe besides photons and standard (active) neutrinos. This short review provides a comprehensive overview of the two problems and of their connection. We review the status of neutrino oscillation anomalies, commenting on the most recent oscillation data and their mutual tensions, and we discuss the constraints from other terrestrial probes. We show the shortcomings of translating light sterile neutrinos in cosmology as additional thermalised relativistic species, produced by neutrino oscillations, and we detail alternative solutions, specifically focusing on neutrino non standard interactions, and on their link to the Hubble constant problem. The impact of a new force leading to dark radiation -- dark matter interactions is also discussed in the realm of new physics in the dark sector.
W. R. B. de Araújo (Secretaria de Educação do Estado de São Paulo, Brazil)🇧🇷 · E. F.Suisso (Instituto Nacional de Propriedade Industrial, INPI, RJ) · J. P. B. C. de Melo (Laboratório de Física Teórica e Computacional - LFTC, Universidade Cruzeiro do Sul / Universidade Cidade de São Paulo, São Paulo, Brazil)🇧🇷 · T. Frederico (Instituto Tecnológico de Aeronáutica, DCTA, São Joé dos Campos, SP, Brazil)🇧🇷 · Kazuo Tsushima (Laboratório de Física Teórica e Computacional - LFTC, Universidade Cruzeiro do Sul / Universidade Cidade de São Paulo, São Paulo, Brazil)🇧🇷
In the present work we study the effect of the scalar spin coupling of constituent quarks on the nucleon electroweak properties by introducing a valence light-front wave function with two momentum scales. By comparing the results obtained with the one scale and two scale wave function models, we have found that the last one has shown a reasonable description of the static observables and ratio in which the position of the zero appears around 10~[GeV/c] or for higher squared momentum transfers. We have also shown results for the axial-vector coupling and the nucleon axial-vector form factor. The best result for was obtained when the parameters of the nucleon wave function model were such that the experimental value of the neutron magnetic moment was described.
Xiang-Yu Zhao🇨🇳 · Yan-Ting Feng🇨🇳 · Feng-Lan Shao🇨🇳 · Rui-Qin Wang🇨🇳 · Jun Song🇨🇳
With the kinetic freeze-out nucleons and antinucleons obtained from the quark combination model, we study the production of light nuclei and antinuclei in the (anti-)nucleon coalescence mechanism in relativistic heavy ion collisions. We derive analytic formulas of the momentum distributions of different light nuclei and apply them to compute transverse momentum () spectra of (anti-)deuterons (, ) and (anti-)tritons (, ) in Au-Au collisions at 7.7, 11.5, 19.6, 27, 39, 54.4 GeV. We find that the experimental data available for these spectra can be well reproduced. We further study the yields and yield ratios of different light (anti-)nuclei and naturally explain their interesting behaviors as a function of the collision energy. We especially point out that the multi-particle yield ratio should be carefully corrected from hyperon weak decays for protons to probe the production characteristics of light nuclei. All of our results show that the coalescence mechanism for (anti-)nucleons plays a dominant role for the production of light nuclei and antinuclei at the RHIC beam energy scan energies.
Sabya Sachi Chatterjee🇫🇷 · Antonio Palazzo🇮🇹
The current data of the two long-baseline accelerator experiments NOA and T2K, shows a tension at more than 90 C.L. for 2 degrees of freedom, in the determination of the standard CP-phase in case of neutrino normal ordering (NO). NOA measures the value close to , while T2K prefers the value of . We show that such a tension can be resolved if one hypothesizes the existence of neutral-current non-standard interactions (NSI) of neutrinos involving the flavor changing type or the sectors with couplings . Remarkably, our analyses show that in the presence of such NSI, both the experiments point towards the same common value of the standard CP-phase , thereby indicating towards the maximal CP-violation in the standard framework. We also show that the best fit values of the new CP-phases or are close to , hence pointing towards the maximal CP-violation in the NSI sector.
Ahmad Jafar Arifi🇰🇷 · Daiki Suenaga🇯🇵 · Atsushi Hosaka🇯🇵 · Yongseok Oh🇰🇷
Decay properties of multi-strangeness and baryon resonances are investigated within the constituent quark model by including relativistic corrections. The strong decay widths of various and resonances are computed and tested for internal quark configurations to pin down their spin-parity () quantum numbers and internal structures. We found that the Roper-like resonances in the multi-strangeness sector have large decay widths bearing resemblances to their siblings in light and heavy baryon sectors. In addition, we obtained the decay ratio for the as , which is consistent with the experimental data when is assigned. This observation holds the possibility that the could naturally be explained as a three-quark state in the quark model. The decays of other low-lying and resonances are systematically analyzed, which would be useful to unveil the structure of these resonances in future experiments.
Mitesh Kumar Behera🇮🇳 · Rukmani Mohanta🇮🇳
In this paper, we investigate the implication of modular symmetry on neutrino oscillation phenomenology in the linear seesaw framework. In order to achieve the well defined mass structure for the light active neutrinos as dictated by the linear seesaw mechanism, we introduce six heavy fermion fields along with a pair of weightons to retain the holomorphic nature of the superpotential. The notable feature of modular symmetry is that, it reduces the usage of flavon fields significantly. In addition, the Yukawa couplings transform non-trivially under the flavor symmetry group and expressed in terms of the Dedekind eta functions, the expansion of which renders numerical simplicity in calculations. We demonstrate that the model framework diligently accommodates all the neutrino oscillation data. Alongside, we also investigate the effect of CP asymmetry generated from the decay of lightest heavy fermions to explain the observed baryon asymmetry through the phenomenon of leptogenesis.
B. M. Hegelich🇺🇸 · L. Labun🇺🇸 · O. Z. Labun🇺🇸 · G. Torrieri🇧🇷 · H. Truran🇧🇷
A model detector undergoing constant, infinite-duration acceleration converges to an equilibrium state described by the Hawking-Unruh temperature . To relate this prediction to experimental observables, a point-like charged particle, such as an electron, is considered in place of the model detector. Instead of the detector's internal degree of freedom, the electron's low-momentum fluctuations in the plane transverse to the acceleration provide a degree of freedom and observables which are compatible with the symmetry and thermalize by interaction with the radiation field. General arguments in the accelerated frame suggest thermalization and a fluctuation-dissipation relation but leave underdetermined the magnitude of either the fluctuation or the dissipation. Lab frame analysis reproduces the radiation losses, described by the classical Lorentz-Abraham-Dirac equation, and reveals a classical stochastic force. We derive the fluctuation-dissipation relation between the radiation losses and stochastic force as well as equipartitation from classical electrodynamics alone. The derivation uses only straightforward statistical definitions to obtain the dissipation and fluctuation dynamics. Since high accelerations are necessary for these dynamics to become important, we compare classical results for the relaxation and diffusion times to strong-field quantum electrodynamics results. We find that experimental realization will require development of more precise observables. Even wakefield accelerators, which offer the largest linear accelerations available in the lab, will require improvement over current technology as well as high statistics to distinguish an effect.
Juan M. Torres-Rincon🇩🇪 · Derek Teaney🇺🇸
We determine the kinetic coefficients of ultrasoft pions using chiral perturbation theory at finite temperature close to the chiral limit. This is used to compute the axial charge diffusion and damping coefficients in the hydrodynamic effective theory for these pion waves. We show that to provide a leading order answer for these coefficients one needs to explore the dynamics of hard, soft, and ultrasoft pion modes, which are represented microscopically by the appropriate kinetic and hydrodynamic descriptions..
Ya-Ping Xie🇨🇳 · Victor P. Goncalves🇧🇷
The exclusive production of vector mesons and photons in collisions is investigated considering three phenomenological saturation models based on distinct assumptions for the treatment of the dipole - hadron scattering amplitude. The latest high precision HERA data for the reduced and vector meson cross sections are used to update the saturation model proposed by Marquet - Peschanski - Soyez (MPS), which predicts that the saturation model is dependent of the squared momentum transfer . The MPS predictions for the photon virtuality, energy and - dependencies of the exclusive , and DVCS cross sections are presented and a detailed comparison with the results derived using the impact parameter saturation models is performed. Our results indicate that a future experimental analysis of the - distribution for exclusive processes in the kinematical range that will covered by the EIC and LHeC, considering the distinct photon polarizations and large values of , will be able to discriminate between the distinct approaches for the QCD dynamics at high energies.
Alessandro Bacchetta🇮🇹 · Francesco Giovanni Celiberto🇮🇹 · Marco Radici🇮🇹
We present exploratory studies of the 3D proton tomography through polarized -odd gluon TMDs at leading twist, obtained in a spectator-model framework. We embody in our approach a flexible parameterization for the spectator-mass spectral function, suited to catch both small- and moderate- effects. All these studies are relevant to unveil the gluon dynamics inside hadrons, which represents a core research line of studies at new-generation colliders, such as the Electron-Ion Collider, NICA-SPD, the High-Luminosity LHC, and the Forward Physics Facility.
Yuval Grossman🇺🇸 · Ameen Ismail🇺🇸 · Joshua T. Ruderman🇺🇸 · Tien-Hsueh Tsai🇺🇸
We look for relations among CKM matrix elements that are not consequences of the Wolfenstein parametrization. In particular, we search for products of CKM elements raised to integer powers that approximately equal . We study the running of the CKM matrix elements and resolve an apparent discrepancy in the literature. To a good approximation only runs, among the Wolfenstein parameters. Using the Standard Model renormalization group we look for CKM relations at energy scales ranging from the electroweak scale to the Planck scale, and we find 19 such relations. These relations could point to structure in the UV, or be numerical accidents. For example, we find that , within accuracy, in the - GeV range. We discuss the implications of this CKM relation for a Yukawa texture in the UV.
Luigi Delle Rose🇪🇸 · Benedict von Harling🇪🇸 · Alex Pomarol🇪🇸
We show how to simplify the calculation of the finite contributions from heavy particles to EFT Wilson coefficients by using on-shell methods. We apply the technique to the one-loop calculation of and , showing how finite contributions can be obtained from the product of tree-level amplitudes. In certain cases, due to a parity symmetry of these amplitudes, the total contribution adds up to zero, as previously found in the literature. Our method allows to search for new natural zeros, as well as to obtain non-zero contributions in a straightforward way.
Dominic Kraatz🇩🇪 · Michel Stillger🇩🇪
We investigate the influence of the allowed unphysical meson decay into a quark-antiquark pair of the three flavour Nambu--Jona-Lasinio (NJL) model on its parameter fixing. This decay manifests in a non-vanishing imaginary part of the corresponding meson propagator and its polarisation loop, respectively. In order to handle the emerging divergent integrals, we focus on the Pauli-Villars, three- and four momentum cutoff regularisation method. Here, we fix the parameters to certain observables, which are effected by the non-vanishing imaginary part. The resulting parameter-sets for each regularisation scheme are compared to each other with and without taking the imaginary part of the polarisation loop into account.
We analyze new data from the COHERENT experiment of the coherent neutrino-nucleus scattering to investigate the electromagnetic interactions of neutrinos. With almost double the statistics and precision now, the statistical significance of the observed process has now enhanced to 11.6. We derive constraints on the electromagnetic properties of neutrinos using the new COHERENT data. The constraints improve by more than a factor of two compared to the previous bounds. Furthermore, we discuss the unique behavior of the neutrino millicharge at lower energy recoils and show its unique dependence on its interference with the standard model contribution, inverse power of recoil energy and the mass of the target particle in comparison to the other interactions.
Wanchen Li🇺🇸 · Anna M. Stasto🇺🇸
We perform the fit to the structure function data from HERA including terms due to the resummation at small . The equation for the unintegrated gluon density is solved, previously established within the renormalization group improved small framework. We find very good description of the structure function and its charm component . The resulting unintegrated gluon density is found to be consistent with the calculations based on similar approaches available in the literature, with only slightly higher intercept value.
Andrea Bevilacqua🇵🇱 · Jerzy Kowalski-Glikman🇵🇱 · Wojciech Wislicki🇵🇱
In this paper we revisit the model of -deformed complex scalar field. We find that this model possesses ten conserved Noether charges that form, under commutators, a representation of (undeformed) Poincaré algebra. It follows that the theory is relativistic and does not break Lorentz invariance. However the spacetime representation of boosts is not standard, and contains a non-local translation, different for positive and negative energy modes. It then follows that although the masses of particles and anti-particles are equal, the theory violates CPT symmetry in a subtle way. We explain why the Jost-Wightman-Greenberg theorem of equivalence of the Poincaré symmetry and CPT fails in our case. Finally, we discuss the phenomenological consequences of the theory and its possible observational signatures.
Samuel Passaglia🇯🇵 · Wayne Hu🇺🇸
Ultralight axions are theoretically interesting and phenomenologically rich dark sector candidates, but they are difficult to track across cosmological timescales because of their fast oscillations. We resolve this problem by developing a novel method to evolve them efficiently and accurately. We first construct an exact effective fluid which at late times matches the axion but which evolves in a simple way. We then approximate this evolution with a carefully chosen equation of state and sound speed. With our scheme we find that we can obtain subpercent accuracy for the linear theory suppression of axion density fluctuations relative to that of cold dark matter without tracking even a single complete oscillation of the axion field. We use our technique to test other approximation schemes and to provide a fitting formula for the transfer function for the matter power spectrum in linear theory in axion models. Implementing our approach in existing cosmological axion codes is straightforward and will help unleash the potential of high-precision next-generation experiments.
Arko Bhaumik🇮🇳 · Soumitra SenGupta🇮🇳
We examine the modulus stabilization mechanism of a warped geometry model with nested warping. Such a model with multiple moduli is known to offer a possible resolution of the fermion mass hierarchy problem in the standard model. A six dimensional doubly warped braneworld model under consideration admits two distinct moduli, with the associated warp factors dynamically generating different physical mass scales on four 3-branes. In order to address the hierarchy problem related to the Higgs mass, both moduli need to be stabilized around their desired values without any extreme fine tuning of parameters. We show that it is possible to stabilize them simultaneously due to the appearence of an effective 4D moduli potential, which is generated by a single bulk scalar field having non-zero VEVs frozen on the 3-branes. We also discuss how the entire mechanism can possibly be understood from a purely gravitational point of view, with higher curvature f(R) contributions in the bulk automatically providing a scalar degree of freedom that can serve as the stabilizing field in the Einstein frame.
Shou-Shan Bao🇨🇳 · Qi-Xuan Xu🇬🇧 · Hong Zhang🇨🇳
The approximate solution of the Klein-Gordon equation for a real scalar field of mass in the geometry of a Kerr black hole obtained by Detweiler \cite{Detweiler:1980uk} is widely used in the analysis of the stability of black holes as well as the search of axion-like particles. In this work, we confirm a missing factor in this solution, which was first identified in Ref.~\cite{Pani:2012bp}. The corrected result has strange features that put questions on the power-counting strategy. We solve this problem by adding the next-to-leading order (NLO) contribution. Compared to the numerical results, the NLO solution reduces the percentage error of the LO solution by a factor of 2 for all important values of . Especially the percentage error is in the region of . The NLO solution also has a compact form and could be used straightforwardly.
* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.