HEP Phenomenology·hep-ph
21 papers—13 primary·8 cross-listed·reconstructed*
We outline the developed approach within the light-cone sum rules at the leading order for calculation of the gravitational form factors related to the nucleon valence quark combinations. The predictions for the gravitational form factor (-term contributions) have been presented.
Spectrum, radii, radial wave functions at origin, decay constants and momentum widths for radial and orbital excited mesons are derived within non-relativistic quark model framework through finding numerical solution of the Schrodinger equation by shooting method. Masses of orbitally excited states are derived with a more simpler method that is developed by combining the uncertainty and variational principles. Masses of mesons are also calculated by using Momentum widths. Besides calculations, theoretical results are compared with the experimental observations which have implications for scalar form factors and leptonic decays of mesons.
Jinmian Li🇨🇳 · Tianjun Li🇨🇳 · Junle Pei🇨🇳 · Wenxing Zhang🇨🇳
The quirk particle carries Lorentz force and long-range infracolor force, while suffers relatively large ionization energy loss inside the detector. It can be indirectly constrained by mono-jet search or directly search through co-planar hits if the confinement scale is not too low ( eV). Considering the ionization energy loss inside tracker, we improve the co-planar search. We also will solve the equation of motion for quirks numerically by including all of the important contributions. Based on our selection strategy, the fb dataset at the LHC will be able to probe the colored fermion/scalar quirks with masses up to {2.1/1.1 TeV}, and the color neutral fermion/scalar quirks with masses up to {450/150 GeV}, respectively.
This model includes a minimal extension of the standard model with and symmetries to explain neutrino masses and mixing along with the dark matter phenomenology. Neutrino phenomenology is explored, consistent with the observation of oscillation parameters and a nonzero reactor mixing angle () is obtained. The singlet Majorana neutrino couples to the third generation of leptons, gives a correct relic density compatible with the Planck data. This model does not allow tree level direct detection, therefore we discuss the loop level effective interaction with the nucleus mediated by gauge boson. Also the constraints from the lepton flavor violating rare decay mode is commented.
S. Modares Vamegh🇮🇷 · M. Haghighat🇮🇷 · S. Mahmoudi🇮🇷 · R. Mohammadi🇮🇷
We consider a vector dark matter (VDM) with a direct coupling with photon. We examine the effect of such an interaction on the CMB polarization to put new constrains on the properties of the DM particles. We show that a partially polarized VDM of the order of temperature fluctuation with a quadrupole distribution leads to a valuable CP for the CMB. In different DM-models the DM-masses range from few to a few . We show that the CP angular power spectrum depends on the mass of VDM as such that for , the CP angular power spectrum is . Therefore, the light VDM with masses less than leads to an unexpected very large CP which can be excluded from the acceptable range of the VDM masses.
Miguel Nebot (Valencia, IFIC-UV, Lisbon, CFTP-IST)🇵🇹
In Two Higgs Doublet Models (2HDMs) shaped by some unbroken symmetry, imposing perturbativity requirements on the quartic couplings can imply that the allowed masses of all the fundamental scalars are bounded from above. This important property is analysed in detail for the only two realistic 2HDMs with an exact symmetry, the case with symmetry and the case with CP symmetry. It is also noticeable that one exception arises in each case: when the vacuum is assumed to respect the imposed symmetry, a decoupling regime can nevertheless appear without violating perturbativity requirements. In both models with an exact symmetry and no decoupling regime, soft symmetry breaking terms can however lead to a decoupling regime: the possibility that this regime might be unnatural, since it requires some fine tuning, is also analysed.
G. Barenboim🇪🇸 · P. Martinez-Mirave🇪🇸 · C. A. Ternes🇪🇸 · M. Tortola🇪🇸
In this paper we investigate neutrino oscillations with altered dispersion relations in the presence of sterile neutrinos. Modified dispersion relations represent an agnostic way to parameterize new physics. Models of this type have been suggested to explain global neutrino oscillation data, including deviations from the standard three-neutrino paradigm as observed by a few experiments. We show that, unfortunately, in this type of models new tensions arise turning them incompatible with global data.
J. Fiaschi🇩🇪 · M. Klasen🇩🇪 · M. Sunder🇩🇪
We present a calculation of slepton pair production at the LHC at next-to-next-to-leading logarithmic (NNLL) accuracy, matched to approximate next-to-next-to-leading order (aNNLO) QCD corrections. We collect the relevant analytical formulae, discuss the matching of logarithmically enhanced and fixed-order results and describe the transformation of parton densities and hadronic cross sections to and from Mellin space. Numerically, we find a moderate increase of invariant-mass distributions and total cross sections with respect to our previous results at next-to-leading logarithmic (NLL) accuracy matched to next-to-leading order (NLO), and more importantly a further significant reduction of the factorisation and renormalisation scale dependence that stabilises our predictions to the permil level. The dependence on other supersymmetric parameters like squark and gluino masses and sbottom mixing that enter only at NLO is found to be weak, i.e.\ less than two percent, as expected.
Alireza Beygi🇩🇪 · S. P. Klevansky🇩🇪 · R. H. Lemmer🇿🇦
Recently quantum simulators have been constructed to investigate experimentally the most prominent theoretical four-point many-body system described by the Hubbard model. By varying the coupling strength of the four-point interaction in relation to the kinetic term, one can analyze the phase structure of the model. This intriguing fact leads us to investigate whether similar Hamiltonians with four-point interactions can also be studied as a function of their four-point coupling strength. In this paper, we reexamine the Nambu-Jona-Lasinio model, regarding it generally beyond the context of quantum chromodynamics. Essentially, it is a model in which particle-antiparticle pairing leads to a BCS-like condensate, with the result that chiral symmetry is broken dynamically in the strong-coupling regime. To study the behavior of the system, it is necessary to move from this regime to a hypothetical regime of weak coupling, altering the coupling strength of the interaction arbitrarily. In order to do this, the gap equation must be regarded as complex and its Riemann surface structure must be known. We do this and obtain a continuous quantum phase transition characterized by the development of a complex order parameter (the dynamically generated mass) from the second sheet of the Riemann surface, as we move into the weak-coupling regime. The power-law behavior of the order parameter in the vicinity of the phase transition point is demonstrated to be independent of the choice of the regularization scheme with the critical exponent as . At the same time, the isovector pseudoscalar modes retain their feature as Goldstone modes and still have zero mass, while the isoscalar scalar meson follows the behavior of the order parameter and gains a width. Energetically, this mode is not favored over the normal, uncondensed mode but would have to be accessed through an excitation process.
Yue Tan🇨🇳 · Jialun Ping🇨🇳
Recently, Belle Collaboration reported a new exotic state with mass at 4625.9 MeV in the positronium annihilation process. Inspired by experiment, we study the tetraquark system with quantum numbers in the framework of chiral constituent quark model with the help of Gaussian expansion method. Two structures, diquark-antidiquark and meson-meson, with all possible color and spin configurations are considered. The result shows that no bound state can be formed. To investigate the possible resonance states, the real scaling method is employed. Several resonance states with energies 4354, 4408, 4469, 4497 and 4531 MeV, are proposed. Taking into account the errors in calculating the mesons, the system errors in the calculation of four-quark system are around 60 MeV. The resonance with energy 4531 MeV is possible the candidate of the newly found state .
Kunio Kaneta🇺🇸 · Yann Mambrini🇫🇷 · Keith A. Olive🇺🇸 · Sarunas Verner🇺🇸
No-scale supergravity provides a successful framework for Starobinsky-like inflation models. Two classes of models can be distinguished depending on the identification of the inflaton with the volume modulus, (C-models), or a matter-like field, (WZ-models). When supersymmetry is broken, the inflationary potential may be perturbed, placing restrictions on the form and scale of the supersymmetry breaking sector. We consider both types of inflationary models in the context of high-scale supersymmetry. We further distinguish between models in which the gravitino mass is below and above the inflationary scale. We examine the mass spectra of the inflationary sector. We also consider in detail mechanisms for leptogenesis for each model when a right-handed neutrino sector, used in the seesaw mechanism to generate neutrino masses, is employed. In the case of C-models, reheating occurs via inflaton decay to two Higgs bosons. However, there is a direct decay channel to the lightest right-handed neutrino which leads to non-thermal leptogenesis. In the case of WZ-models, in order to achieve reheating, we associate the matter-like inflaton with one of the right-handed sneutrinos whose decay to the lightest right handed neutrino simultaneously reheats the Universe and generates the baryon asymmetry through leptogenesis.
A model for spontaneous symmetry breaking using a specific form of the bumblebee model is analyzed in the context of a Schwarzschild background metric. The resulting back reaction of the symmetry-breaking field on the metric is computed to second order. Consistency with conventional (pseudo)Riemannian geometry is demonstrated. This background field is coupled to fermions via a spin-dependent CPT-violating coupling term of a type commonly considered in the Standard-Model Extension. The perturbations of various orbital trajectories are discussed. Specifically, a spin-dependent orbital velocity is found as well as a spin-dependent precession rate.
Tomáš Husek (IFIC, Valencia)🇪🇸 · Stefan Leupold (Uppsala U.)🇸🇪
Electromagnetic form factors serve to explore the intrinsic structure of nucleons and their strangeness partners. With electron scattering at low energies the electromagnetic moments and radii of nucleons can be deduced. The corresponding experiments for hyperons are limited because of the unstable nature of the hyperons. Only for one process this turns to an advantage: the decay of the neutral Sigma hyperon to a Lambda hyperon and a real or virtual photon. Due to limited phase space the effects caused by the Sigma-to-Lambda transition form factors compete with the QED radiative corrections for the decay . These QED corrections are addressed in the present work, evaluated beyond the soft-photon approximation, i.e., over the whole range of the Dalitz plot and with no restrictions on the energy of the radiative photon.
Eleonora Di Valentino🇬🇧 · Alessandro Melchiorri🇮🇹 · Joseph Silk🇫🇷
The recent Planck Legacy 2018 release has confirmed the presence of an enhanced lensing amplitude in CMB power spectra compared to that predicted in the standard CDM model. A closed universe can provide a physical explanation for this effect, with the Planck CMB spectra now preferring a positive curvature at more than C.L. Here we further investigate the evidence for a closed universe from Planck, showing that positive curvature naturally explains the anomalous lensing amplitude and demonstrating that it also removes a well-known tension within the Planck data set concerning the values of cosmological parameters derived at different angular scales. We show that since the Planck power spectra prefer a closed universe, discordances higher than generally estimated arise for most of the local cosmological observables, including BAO. The assumption of a flat universe could, therefore, mask a cosmological crisis where disparate observed properties of the Universe appear to be mutually inconsistent. Future measurements are needed to clarify whether the observed discordances are due to undetected systematics, or to new physics, or simply are a statistical fluctuation.
Ryotaro Kase🇯🇵 · Shinji Tsujikawa🇯🇵
We investigate a dark energy scenario in which a canonical scalar field is coupled to the four velocity of cold dark matter (CDM) through a derivative interaction . The coupling is described by an interacting Lagrangian , where depends on and . We derive stability conditions of linear scalar perturbations for the wavelength deep inside the Hubble radius and show that the effective CDM sound speed is close to 0 as in the standard uncoupled case, while the scalar-field propagation speed is affected by the interacting term . Under a quasi-static approximation, we also obtain a general expression of the effective gravitational coupling felt by the CDM perturbation. We study the late-time cosmological dynamics for the coupling and show that the gravitational coupling weaker than the Newton constant can be naturally realized for on scales relevant to the growth of large-scale structures. This allows the possibility for alleviating the tension of between low- and high-redshift measurements.
Z.R. Kordov🇦🇺 · R. Horsley🇬🇧 · Y. Nakamura🇯🇵 · H. Perlt🇩🇪 · P.E.L. Rakow🇬🇧 · G. Schierholz🇩🇪 · H. Stüben🇩🇪 · R.D. Young🇦🇺 · J.M. Zanotti🇦🇺
Mixing in the - system is a direct consequence of broken isospin symmetry and is a measure of both isospin-symmetry breaking as well as general SU(3)-flavour symmetry breaking. In this work we present a new scheme for calculating the extent of - mixing using simulations in lattice QCD+QED and perform several extrapolations that compare well with various past determinations. Our scheme allows us to easily contrast the QCD-only mixing case with the full QCD+QED mixing.
Guy D. Moore🇩🇪 · Niels Schlusser🇩🇪
EQCD is a 3D bosonic theory containing SU(3) and an adjoint scalar, which efficiently describes the infrared, nonperturbative sector of hot QCD and which is highly amenable to lattice study. We improve the matching between lattice and continuum EQCD by determining the final unknown coefficient in the matching, an additive scalar mass renormalization. We do this numerically by using the symmetry-breaking phase transition line of EQCD as a line of constant physics. This prepares the ground for a precision study of the transverse momentum diffusion coefficient within this theory.
D. Alesini🇮🇹 · D. Babusci🇮🇹 · P. Beltrame S.J.🇺🇸 · F. Björkeroth🇮🇹 · F. Bossi🇮🇹 · P. Ciambrone🇮🇹 · G. Delle Monache🇮🇹 · D. Di Gioacchino🇮🇹 · P. Falferi🇮🇹 · A. Gallo🇮🇹 · C. Gatti🇮🇹 · A. Ghigo🇮🇹 and 17 other authors
The last decade witnessed an increasing interest in axions and axion-like particles with many theoretical works published and many new experimental proposals that started a real race towards their discovery. This paper is the Conceptual Design Report of the KLASH (KLoe magnet for Axion SearcH) experiment at the Laboratori Nazionali di Frascati (LNF). The idea of this experiment has been stimulated by the availability of the large volume superconducting magnet, with a moderate magnetic field of 0.6 T, used in the KLOE detector at the DAFNE collider. The main conclusion we draw from this report is the possibility to build and put in operation at LNF in 2-3 years a large haloscope with the sensitivity to KSVZ axions in the low mass range between 0.2 and 1 eV, complementary to that of other experiments. Timeline and cost are competitive with respect to other proposals in the same mass region thanks to the availability of most of the infrastructure, in particular the superconducting magnet and the cryogenics plant.
Emilia Leogrande🇨🇭 · Philipp Roloff🇨🇭 · Ulrike Schnoor🇨🇭 · Matthias Weber🇨🇭
In this note the production in the all-hadronic final state in collisions at the Compact Linear Collider is studied at the 3 TeV stage. At high energies, the events have an experimental signature of back-to-back approximately mono-energetic large jets. Each of these jets contains two sub-jets and substructure compatible with two original objects. The study is based on full simulation including the detector response, as well as the presence of beam-induced background from . Results on the measurement of the total cross section are given, and the potential to measure angular asymmetry observables is discussed.
The effects of the Dirac sea of the nucleons are investigated within a covariant model of the hadronic interaction. We extend the usual Mean Field Approximation and present a procedure to deal with divergences which are proportional to polynomials on the magnetic field intensity. For this purpose a nucleon propagator is used which takes accounts of the full effect of the magnetic field as well as the presence of the anomalous magnetic moments of both protons and neutrons. We examine single particle properties and bulk thermodynamical quantities and conclude that within a reasonable range of densities and magnetic intensities the effects found are moderate.
Abdeljalil Habjia
Statistical tools have been developed to quantify the agreement between a hypothesis or a model and the observed data for probabilistic phenomena. In this work, we define statistical methods used to measure the properties of the higgs boson in the LHC on the one hand, but also to evaluate the uncertainty and precision on these measurements. They are based on the definition of a likelihood function whose construction will be detailed below. The challenge of HEP is to generate tons of data and to develop powerful analyses to tell if the data indeed contains evidence for the new particle, and confirm it's the expected Higgs boson.
* 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.