HEP Phenomenology·hep-ph
26 papers—17 primary·9 cross-listed·reconstructed*
Ted Rogers🇺🇸 · Fatma Aslan🇺🇸 · Mariaelena Boglione🇮🇹 · J. Osvaldo Gonzalez-Hernandez🇮🇹 · Tommaso Rainaldi🇺🇸 · Andrea Simonelli🇺🇸
This talk summarized work done recently to organize the steps for implementing TMD phenomenology in a way optimized for contexts where the extraction and interpretation of hadronic structures and nonperturbative effects is the primary driving motivation.
Xin-Kai Wen🇨🇳 · Bin Yan🇨🇳 · Zhite Yu🇺🇸 · C.-P. Yuan🇺🇸
We propose a novel method to probe light-quark dipole moments by examining the azimuthal asymmetries between a collinear pair of hadrons in semi-inclusive deep inelastic lepton scattering off an unpolarized proton target at the Electron-Ion Collider. These asymmetries provide a means to observe transversely polarized quarks, which arise exclusively from the interference between the dipole and the Standard Model interactions, thereby depending linearly on the dipole couplings. We demonstrate that this novel approach can enhance current constraints on light-quark dipole operators by an order of magnitude, free from contamination of other new physics effects. Furthermore, it allows for a simultaneous determination of both the real and imaginary parts of the dipole couplings, offering a new avenue for investigating potential -violating effects at high energies.
Sameer Jain🇮🇳 · Shubham Sharma🇮🇳 · Harleen Dahiya🇮🇳
We investigate quantum chromodynamics (QCD) in this study by computing chiral-even generalized parton distributions (GPDs) at twist- using the light-front quark-diquark model (LFQDM), particularly when the longitudinal momentum transfer is zero. We provide a detailed analysis of the twist- chiral-even GPD's dependence on the longitudinal momentum fraction () and the momentum transfer () by illustrating their behavior through extensive two-dimensional (-D) and three-dimensional (-D) visualizations. Our investigation also reveals the intricate relationships between these GPDs and other distribution functions (DFs) such as generalized transverse-momentum dependent distributions (GTMDs), transverse momentum-dependent parton distributions (TMDs), and parton distribution functions (PDFs). Our study also includes the connected form factors (FFs) which are crucial in understanding the internal structure of hadrons. Additionally, we provide impact parameter GPD plots to offer insights into the spatial distribution of partons.
Navpreet Kaur🇮🇳 · Harleen Dahiya🇮🇳
We have performed the structural analysis of low-lying octet baryon members by assuming charge-isospin symmetry among quark flavors in transverse and longitudinal space. Using the light-cone spectator diquark model, we have investigated the electromagnetic form factors of the octet baryons and have compared them with the available data. Model scale has been estimated by comparing the valence quark's parton distribution function (PDF) of proton with the result of CTEQ5L parameterization. A comparative analysis of PDFs and generalized parton distributions (GPDs) for non-zero skewness among octet baryons has also been demonstrated. Fourier transform of the deeply virtual Compton scattering amplitude with respect to skewness has been further applied to study the diffraction patterns in the boost-invariant longitudinal position space.
Boris Betancourt Kamenetskaia🇩🇪 · Nissim Fraija🇲🇽 · Gonzalo Herrera🇺🇸
Axion Like Particles (ALPs) can be produced in Gamma Ray Bursts, altering the polarization of the electromagnetic emission in these events. For the first time, we derive bounds on the axion-photon coupling from polarization measurements of GRB 221009A, performing a full calculation of the Stokes parameters, as it is typically done in the astrophysics community. Within astrophysical uncertainties, our limits on the axion-photon coupling are competitive with complementary probes in the axion mass range eV eV, further allowing to probe motivated parameter space of ALP dark matter.
Lianyou Shan🇨🇳 · Lei Wang🇨🇳 · Jin Min Yang🇨🇳 · Rui Zhu🇨🇳
A light (GeV mass) long-lived ( around dozens of millimeters) CP-odd scalar can be readily predicted in new physics models. In this work we investigate the Higgs decay into such a light scalar plus a -boson and take the aligned two-Higgs-doublet model (2HDM) as an example. This light long-lived scalar, with the dominant decay to tau leptons, will fly over a distance from the production point and present a displaced vertex in an Inner Detector of a generally purposed experiment like ATLAS or CMS. In our study we focus on the LHC experiment and perform Monte Carlo simulations for the signal and backgrounds. We demonstrate some benchmark points for the aligned 2HDM and find the signal to be detectable when the luminosity is accumulated to 300 fb. So our study suggests an experimental search for this process in the ongoing LHC.
Andrea Barontini🇮🇹 · Alessandro Candido🇮🇹 · Felix Hekhorn🇫🇮 · Giacomo Magni🇳🇱 · Roy Stegeman🇬🇧
We present a new prescription to account for heavy quark mass effects in the determination of parton distribution functions (PDFs) based on the FONLL scheme. Our prescription makes explicit use of the freedom to choose the number of active flavors at a given scale and, thus, use coexisting PDFs with different active flavor number. This new prescription is perturbatively equivalent to the former but improves the implementation in two ways. First, it can be naturally generalized to account simultaneously for multiple heavy quark effects, such as charm and bottom effects, which can both be relevant at the same scale due to the small mass difference. Second, it can be trivially generalized to use at any fixed-order or collinear resummed accuracy, while previous prescriptions required ad-hoc expansions of the DGLAP evolution kernels for each coefficient. We supplement the paper with codes for the computation of deep inelastic scattering observables in this new prescription.
Gurjit Kaur🇮🇳 · Gulsheen Ahuja🇮🇳 · Dheeraj Shukla🇮🇳 · Manmohan Gupta🇮🇳
Without adhering to any specific model, we have presented 4 X 4 quark mixing matrix as an extension of the 3 X 3 PDG parametrization of the CKM matrix. Using unitarity constraints as well as the hierarchy among the elements of the 3 X 3 CKM matrix, we have found the hierarchy among the 4th row and 4th column elements of the 4 X 4 quark mixing matrix. Further, for the fourth generation case, we have explicitly found the 9 independent rephasing invariant parameters J_4X4. Also, using phenomenological estimates of the 4th row and 4th column elements, we have numerically evaluated these 9 parameters.
Peter Braun-Munzinger🇩🇪 · Krzysztof Redlich🇵🇱 · Natasha Sharma🇮🇳 · Johanna Stachel🇩🇪
We present the production systematics of open charm hadron yields in high-energy collisions and their description based on the Statistical Hadronization Model of charm (SHMc). The rapidity density of mesons and baryons in heavy ion and proton-proton collisions is analyzed for different collision energies and centralities. The SHMc is extended to open charm production in minimum-bias and high-multiplicity pp collisions. In this context, we use the link established in [1,2], between the rapidity density of open charm hadron yields, , and the rapidity density of charm-anticharm quark pairs, . We demonstrate that, in pp, pA and AA collisions, scales in leading order with and for open charm mesons, and the slope coefficient is quantified by the appropriate thermal density ratio calculated in the SHMc at the chiral crossover temperature, MeV. The slope coefficient for differs at by a factor of which is attributed to missing charmed-baryon resonances in the PDG. It is also shown that exhibits power-law scaling with the charged-particle pseudo-rapidity density in high energy collisions and within uncertainties. Furthermore, presently available data on different ratios of open charm rapidity densities in high-energy collisions are independent of collision energy and system size, as expected in the SHMc.
Simran Arora🇮🇳 · Devabrat Mahanta🇮🇳 · B.C. Chauhan🇮🇳
We propose an extension of the minimal scotogenic model with a triplet fermion and a singlet scalar. An imposed symmetry allows only diagonal Yukawa couplings among different generations of SM leptons and right-handed singlet neutrinos. The Yukawa coupling of the triplet fermion with the inert doublet positively contributes to the muon anomalous magnetic moment. The imposed symmetry forbids the conventional leptogenesis from the lightest right-handed neutrino decay. A net lepton asymmetry can be generated in the muonic sector from and triplet fermion decay through resonant leptogenesis scenario. The Yukawa coupling of triplet plays significant role both in leptogenesis and in the anomalous magnetic moment of the muon. We show a viable parameter space for TeV scale leptogenesis while explaining the Fermi lab results. The inert scalar is the dark matter candidate in this model. The Muon and dark matter both favor the same parameter space for mass of the dark matter and the triplet fermion.
Satyajit Puhan🇮🇳 · Narinder Kumar🇮🇳 · Harleen Dahiya🇮🇳
In this work, we have calculated the photon leading-twist T-even transverse momentum dependent parton distribution functions (TMDs). For these calculations, we have treated photon as a state of quark anti-quark pair and represent the TMDs in explicit form of helicity amplitudes. We have presented all the T-even TMDs for the photon being massless (real) and massive (virtual). We have also compared our longitudinally and transversely polarized TMDs results for different photon masses. The collinear parton distribution functions (PDFs) have been predicted for both the real and virtual photon cases. The results for the unpolarized PDF of our calculations are in good agreement with other model predictions. In addition to this, we have also discussed the spin-spin correlations between the quark and photon.
Ritwik Acharyya🇮🇳 · Satyajit Puhan🇮🇳 · Narinder Kumar🇮🇳 · Harleen Dahiya🇮🇳
We have investigated the ground state (), radially excited states () and () along with the orbitally excited state () for the heavy charmonia () and bottomonia () mesons in the light-front quark model (LFQM). The light-front wave functions have been successful in explaining various physical properties of meson states in the past, especially for the and states. However, studies regarding the radially excited state and orbitally excited state have hardly been pursued before. In this study, we take up these two excited states and investigate the electromagnetic form factors (EMFFs), charge radii, decay constants, parton distribution functions (PDFs) and the distribution amplitudes (DAs) for the quarkonia system. For the sake of completeness, we have also included the study of the ground and the first excited states of quarkonia mesons. We have also illustrated the 3D wave functions for the radially excited states in order to study their nodal structures.
Shubham Sharma🇮🇳 · Sameer Jain🇮🇳 · Harleen Dahiya🇮🇳
This study investigates the sub-leading twist generalized transverse momentum dependent distributions (GTMDs) of a proton within the light-front quark-diquark model (LFQDM) framework. We solve the parametrization equations for the Dirac matrix structure to yield the explicit GTMD expressions for scalar as well as vector diquark configurations for active and quarks. This analysis addresses the multi-dimensional nature of GTMDs by exploring their dependencies on one or two variables while keeping others fixed. Additionally, we extract transverse momentum dependent form factors (TMFFs) from GTMDs by integrating over the longitudinal momentum fraction . The study uses -dimensional plots to illustrate the variation of TMFFs with the quark's transverse momentum and the transverse momentum transfer to the proton .
Satyajit Puhan🇮🇳 · Harleen Dahiya🇮🇳
We have investigated the unpolarized valence quark generalized parton distribution functions (GPDs) and parton distribution functions (PDFs) for heavy spin-, - and -mesons in the light-front quark model (LFQM). PDFs have been extracted from unpolarized transverse momentum-dependent parton distribution functions (TMDs). We have solved the quark-quark correlation function to have an unpolarized GPD. The unpolarized GPDs at zero skewness () lead to describing the electromagnetic form factors (EMFFs) () and gravitational form factors (GFFs)() of the mesons.
Antonio Gómez-Bañón🇪🇸 · Kai Bartnick🇩🇪 · Konstantin Springmann🇮🇱 · José A. Pons🇪🇸
The existence of light QCD axions, whose mass depends on an additional free parameter, can lead to a new ground state of matter, where the sourced axion field reduces the nucleon effective mass. The presence of the axion field has structural consequences, in particular, it results in a thinner (or even prevents its existence) heat-blanketing envelope, significantly altering the cooling patterns of neutron stars. We exploit the anomalous cooling behavior to constrain previously uncharted regions of the axion parameter space by comparing model predictions with existing data from isolated neutron stars. Notably, this analysis does not require the light QCD axion to be the dark matter candidate.
Prudhvi N. Bhattiprolu🇺🇸 · Robert McGehee🇺🇸 · Evan Petrosky🇺🇸 · Aaron Pierce🇺🇸
A Dark Sink uses dark-sector interactions to siphon energy from dark matter to lighter dark degrees of freedom, i.e. dark radiation. Here, we extend dark matter models containing a Dark Sink to sub-MeV masses. We consider a Dark Sink model where the dark matter is charged under a light dark photon that has kinetic mixing with the Standard Model. For sub-MeV dark matter masses, plasmon decays are the dominant mechanism for transferring energy to the dark sector. Relative to a standard freeze-in cosmology, reproducing the observed dark matter density in a Dark Sink structure requires an increase in the dark matter couplings to the Standard Model, and hence increased direct detection cross sections. These models provide benchmarks for current and upcoming direct detection experiments. Accounting for plasmon effects, we derive the range of possible dark matter masses and cross sections for Dark Sink models in the sub-MeV regime. We make code available to reproduce our benchmarks; it may be of use for other freeze-in scenarios, including those where plasmon decays to the dark matter are important.
At finite temperature, the coupling of an axion to non-Abelian gauge fields causes dissipation due to sphaleron heating. This mechanism has been considered as ideal for realizing warm inflation since it can lead to large thermal friction while preserving the flatness of the potential. We show, however, that requiring standard properties of an axion -- in particular a discrete shift symmetry -- excludes the strong regime of warm slow-roll inflation, in which thermal friction dominates. The present argument, which does not rely on any phenomenological input, leaves room for the weak regime of warm axion inflation, but in this case a super-Planckian decay constant represents a well-known issue. Finally, we discuss non-minimal and axion-like models as way out.
Cezar Condeescu🇷🇴 · Andrei Micu🇷🇴
In this paper we give an extensive description of Weyl quadratic gravity as the gauge theory of the Weyl group. The previously discovered (vectorial) torsion/non-metricity equivalence is shown to be built-in as it corresponds to a redefinition of the generators of the Weyl group. We present a generalisation of the torsion/non-metricity duality which includes, aside from the vector, also a traceless 3-tensor with two antisymmetric indices and vanishing skew symmetric part. A discussion of this relation in the case of minimally coupled matter fields is given. We further point out that a Rarita-Schwinger field can couple minimally to all the components of torsion and some components of non-metricity. Alongside we present the same gauge construction for the Poincaré and conformal groups. We show that even though the Weyl group is a subgroup of the conformal group, the gauge theory of the latter is actually only a special case of Weyl quadratic gravity.
We review recent developments in physical implications of Weyl conformal geometry. The associated Weyl quadratic gravity action is a gauge theory of the Weyl group of dilatations and Poincaré symmetry. Weyl conformal geometry is defined by equivalence classes of the metric and Weyl gauge field (), related by Weyl gauge transformations. Weyl geometry can be seen as a covariantised version of Riemannian geometry with respect to Weyl gauge symmetry (of dilatations). This Weyl gauge-covariant formulation of Weyl geometry is metric, which avoids century-old criticisms on the physical relevance of this geometry, that ignored its gauge symmetry. Weyl quadratic gravity and its geometry have interesting properties: a) Weyl gauge symmetry is spontaneously broken and Einstein-Hilbert gravity and Riemannian geometry are recovered, with ; b) this is the only true gauge theory of a space-time symmetry i.e. with a physical (Weyl) gauge boson (); c) all fields and masses have geometric origin (with no added scalar fields); d) the theory has a Weyl gauge invariant geometric regularisation (by ) in dimensions and it is Weyl-anomaly free; this anomaly is recovered in the broken phase after massive decouples; e) the theory is the leading order of the general Weyl gauge invariant Dirac-Born-Infeld (WDBI) action of Weyl conformal geometry in dimensions; f) in the limit of vanishing Weyl gauge current, one obtains conformal gravity; g) finally, Standard Model (SM) has a natural embedding in conformal geometry with no new degrees of freedom, with successful Starobinsky-Higgs inflation. Briefly, Weyl conformal geometry generates a (quantum) gauge theory of gravity, given by Weyl quadratic gravity, and leads to a unified description, by the gauge principle, of Einstein-Hilbert gravity and SM interactions.
Daniele Fargion🇮🇹 · Pier Giorgio De Sanctis Lucentini🇷🇺 · Maxim Yu. Khlopov🇫🇷
The ultra-high-energy cosmic ray (UHECR) puzzle is reviewed under the hints of a few basic results: clustering, anisotropy, asymmetry, bending, and composition changes with energies. We show how the lightest UHECR nuclei from the nearest AGN or Star-Burst sources, located inside a few Mpc Local Sheets, may explain, at best, the observed clustering of Hot Spots at tens EeV energy. Among the possible local extragalactic candidate sources, we derived the main contribution of very few galactic sources. These are located in the Local Sheet plane within a distance of a few Mpc, ejecting UHECR at a few tens of EeV energy. UHECR also shine at lower energies of several EeV, partially feeding the Auger dipole by LMC and possibly a few nearer galactic sources. For the very recent highest energy UHECR event, if a nucleon, it may be explained by a model based on the scattering of UHE ZeV neutrinos on low-mass relic neutrinos. Such scatterings are capable of correlating, via Z boson resonance, the most distant cosmic sources above the GZK bound with such an enigmatic UHECR event. Otherwise, these extreme events, if made by the heaviest composition, could originate from the largest bending trajectory of heaviest nuclei or from nearby sources, even galactic ones. In summary, the present lightest to heavy nuclei model UHECR from the Local Sheet could successfully correlate UHECR clustering with the nearest galaxies and AGN. Heavy UHECR may shine by being widely deflected from the Local Sheet or from past galactic, GRB, or SGR explosive ejection.
Satyajit Puhan🇮🇳 · Navpreet Kaur🇮🇳 · Arvind Kumar🇮🇳 · Suneel Dutt🇮🇳 · Harleen Dahiya🇮🇳
We have calculated the valence quark distributions of the lightest pseudoscalar meson, pions, in the isospin asymmetric nuclear matter at zero and finite temperature employing a light-cone quark model. The medium modifications in the pion properties have been stimulated through the effective quark masses computed using the chiral SU() quark mean field model. We have primarily focused on the impact of isospin asymmetric medium on the distribution amplitudes (DAs) and parton distribution functions (PDFs) of a valence quark for different baryon density and temperature values. Also, the DAs and PDFs have been evolved to GeV and GeV for different densities of nuclear medium and results have been compared with the available experimental data. The DAs and PDFs are found to modify substantially as a function of baryon density as compared to temperature and isospin asymmetry of the medium.
Yao Bai🇨🇳 · Ting-Long Feng🇨🇳 · Suro Kim🇰🇷 · Cheng-Yang Lee🇨🇳 · Lei-Hua Liu🇨🇳 · Wangping Zhao🇨🇳 · Siyi Zhou🇨🇳
Pseudo-Hermitian system is a class of non-Hermitian system with Hamiltonian satisfying the condition . We develop the in-in and Schwinger Keldysh formalism to calculate cosmological correlators for pseudo-Hermitian systems. We study a model consists of massive symplectic fermions coupled to the primordial curvature perturbation. The three-point function for the primordial curvature perturbation is computed up to one-loop and compared to earlier work where the loop correction comes from a massive scalar boson. The two results differ by a minus sign. Therefore, the one loop correction to the three-point function cannot be used to distinguished scalar bosons and symplectic fermions. To conclude, we discuss possibilities where the scalar bosons and symplectic fermions may be distinguished.
Gia Dvali🇩🇪 · Archil Kobakhidze🇦🇺 · Otari Sakhelashvili🇦🇺
We argue that the Standard Model is accompanied by a new pseudo-scalar degree of freedom, -meson, which cancels the topological susceptibility of the electroweak vacuum and gets its mass from this effect. The prediction is based on the analyticity properties of the Chern-Simons correlator combined with the basic features of gravity. Depending on the quality level of the -symmetry, emerges as a pseudo-Goldstone boson or as a Stückelberg -form of the electroweak gauge redundancy. An intriguing scenario of the first category is the emergence of in the form of the phase of a -violating fermion condensate triggered by the instantons, somewhat similar to -meson in QCD. Regardless of its origin, the presence of -meson in the theory appears to be a matter of consistency.
Michael P. Kinach🇨🇦 · Matthew W. Choptuik🇨🇦
We investigate the dynamics of gauged Q-balls using fully three-dimensional numerical simulations. We consider two different scenarios: first, the classical stability of gauged Q-balls with respect to generic three-dimensional perturbations, and second, the behaviour of gauged Q-balls during head-on and off-axis collisions at relativistic velocities. With regard to stability, we find that there exist gauged Q-ball configurations which are classically stable in both logarithmic and polynomial scalar field models. With regard to relativistic collisions, we find that the dynamics can depend on many different parameters such as the collision velocity, relative phase, relative charge, and impact parameter of the colliding Q-balls.
This set of notes was designed to accompany two hours of lectures and practical exercises at the New Horizons for Psi workshop in Lisbon in July 2024 entitled "Studying fundamental fields with numerical relativity". Numerical relativity is a tool used to help understand the behaviours of metric and matter fields in dynamical, strong gravity situations. It has been used to study a range of situations involving fundamental fields, including superradiance, modified gravity, dynamical friction, dark matter accretion and early universe cosmology. The purpose of this course is to provide some background and hands-on experience in numerical relativity that will help students to better understand the possibilities provided by this tool, as well as its limitations.
Arvind Kumar🇮🇳 · Amruta Mishra🇮🇳
In the present work we explore the possibilities of the formation of bound states of neutral pseudoscalar mesons , and and the vector meson , with the nuclei C, O, Ca and Pb, calculating their binding energy and absorption decay width. To calculate the optical potentials of these mesons in different nuclei under study, we shall use the chiral SU(3) hadronic mean field model, in which the properties of nucleons in the medium are modified through the scalar isoscalar fields and and the scalar-isovector field . The scalar-isovector field account for the finite isospin asymmetry of different nuclei having asymmetry in number of protons and neutrons. The binding energy and absorption decay width of mesons are calculated for the ground state and some of possible excited states of the nuclei. In the chiral SU(3) model, the mesons , and are observed to have significant negative mass shift upto nuclear saturation density which lead to the possibility of the bound states at least for ground states and some of excited states in case of heavy nuclei. For the pseudoscalar singlet and the vector meson the mass shift obtained are found to be small and bound states are not formed. The present calculations are compared with different studies available in the field and will be useful in understanding the outcomes from different experimental facilities focusing on this area of research.
* 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.