We investigate the relations between transverse momentum dependent parton distributions (TMDs) and generalized parton distributions (GPDs) in a light-front quark-diquark model motivated by soft wall AdS/QCD. Many relations are found to have similar structure in different models. It is found that a relation between the Sivers function and the GPD Eq can be obtained in this model in terms of a lensing function. The quark orbital angular momentum is calculated and the results are compared with the results in other similar models. Implications of the results are discussed. Relations among different TMDs in the model are also presented.
We develop a numerical method to nonperturbatively study scattering and gluon emission of a quark from a colored target using a light-front Hamiltonian approach. The target is described as a classical color field, as in the Color Glass Condensate effective theory. The Fock space of the scattering system is restricted to the ∣q⟩+∣qg⟩ sectors, but the time evolution of this truncated system is solved exactly. This method allows us to study the interplay between coherence and multiple scattering in gluon emission. It could be applied both to studying subeikonal effects in high energy scattering and to understanding jet quenching in a hot plasma.
Using a extended version of the Quantum Hadrodynamics (QHD), I propose a new microscopic equation of state (EoS) able to correctly reproduce the main properties of symmetric nuclear matter at the saturation density, as well produce massive neutron stars and satisfactory results for the radius and the tidal parameter Λ. I show that even when hyperons are present, this EoS is able to reproduce at least 2.00 solar masses neutron star. The constraints about the radius of a 2.00M⊙ and the minimum mass that enable direct Urca effect are also checked.
In this paper we investigate the (g−2)μ discrepancy in the context of the R-parity conserving next-to-minimal supersymmetric Standard Model plus right-handed neutrinos superfields. The model has the ability to reproduce neutrino physics data and includes the interesting possibility to have the right-handed sneutrino as the lightest supersymmetric particle and a viable dark matter candidate. Since right-handed sneutrinos are singlets, no new contributions for δaμ with respect to the MSSM and NMSSM are present. However, the possibility to have the right-handed sneutrino as the lightest supersymmetric particle opens new ways to escape Large Hadron Collider and direct detection constraints. In particular, we find that dark matter masses within 10≲mν~R≲600 GeV are fully compatible with current experimental constraints. Remarkably, not only spectra with light sleptons are needed, but we obtain solutions with mμ~≳600 GeV in the entire dark matter mass range that could be probed by new (g−2)μ data in the near future. In addition, dark matter direct detection experiments will be able to explore a sizable portion of the allowed parameter space with mν~R≲300 GeV, while indirect detection experiments will be able to probe a much smaller fraction within 200≲mν~R≲350 GeV.
Fireballs created in relativistic heavy-ion collisions at different beam energies have been argued to follow different trajectories in the QCD phase diagram in which the QCD critical point serves as a landmark. Using a (1+1)-dimensional model setting with transverse homogeneity, we study the complexities introduced by the fact that the evolution history of each fireball cannot be characterized by a single trajectory but rather covers an entire swath of the phase diagram, with the finally emitted hadron spectra integrating over contributions from many different trajectories. Studying the phase diagram trajectories of fluid cells at different space-time rapidities, we explore how baryon diffusion shuffles them around, and how they are affected by critical dynamics near the QCD critical point. We find a striking insensitivity of baryon diffusion to critical effects. Its origins are analyzed and possible implications discussed.
In order to investigate the tomographical structure of light pseudoscalar mesons, particularly, pion and kaon, we study the valence quark distribution function (PDF) and the generalized parton distributions (GPDs) using light-cone quark model (LCQM).
We calculate non-singlet quark operator matrix elements of deep-inelastic scattering in the chiral limit including operators with total derivatives. This extends previous calculations with zero-momentum transfer through the operator vertex which provides the well-known anomalous dimensions for the evolution of parton distributions, as well as calculations in off-forward kinematics utilizing conformal symmetry. Non-vanishing momentum-flow through the operator vertex leads to mixing with total derivative operators under renormalization. In the limit of a large number of quark flavors nf and for low moments in full QCD, we determine the anomalous dimension matrix to fifth order in the perturbative expansion in the strong coupling αs in the \mboxMS-scheme. We exploit consistency relations for the anomalous dimension matrix which follow from the renormalization structure of the operators, combined with a direct calculation of the relevant diagrams up to fourth order.
The pion structure is represented by Generelazed parton distribution functions (GPDs). The momentum transfer dependence of GPDs of the pion was obtained on the basis of the form of GPDs of the nucleon in the framework of the high energy generalized structure (HEGS) model. To this end, different forms of PDFs of the pion of various Collaborations were examined with taking into account the available experimental data on the pion form factors. As a result, the electromagnetic and gravitomagnetic form factors of the pion were calculated. They were used in the framework of the HEGS model with the electromagnetic and gravitomagnetic form factors of the proton for describing pion-nucleon elastic scattering in a wide energy and momentum transfer region with a minimum of fitting parameters. The properties of the obtained scattering amplitude were analyzed.
We discuss photon-photon fusion mechanisms of dilepton production in proton-proton collisions with rapidity gap in the main detector and one forward proton in the forward proton detectors. This is relevant for the LHC measurements by ATLAS+AFP and CMS+PPS. Transverse momenta of the intermediate photons are taken into account and photon fluxes are expressed in terms of proton electromagnetic form factors and structure functions. Differential distributions in ξ1/2, Mll, Yll, pt,ll, MR %pamietac wyjasnic M_R w tekscie are shown and the competition of different mechanisms is discussed. Both double-elastic and single-dissociative processes are included in the analysis. Different parametrizations of the structure functions are used. We discuss also mechanism with one forward Δ+ isobar, or other proton resonances in the final state. The role of several cuts is studied. We also use SuperChic generator and compare corresponding results to the results of our codes. The soft rapidity gap survival factor is calculated for each contribution separately. The gap survival factor for the single-dissociative mechanism due to minijet emission into the main detector is calculated in addition. It depends on the type of contribution (fully elastic, single dissociation, double dissociation). The soft rapidity gap survival factor for the case of single proton measurement is significantly smaller than that for the inclusive case (no proton measurement). We find only weak dependence on the invariant mass of the dilepton system as well as the lepton pair transverse momentum and sizeable dependence on the pair rapidity. The latter effect is rather difficult to identify experimentally.
We study hard 1→2 final-state parton splittings in the medium, and put special emphasis on calculating the Wilson line correlators that appear in these calculations. As partons go through the medium their color continuously rotates, an effect that is encapsulated in a Wilson line along their trajectory. When calculating observables, one typically has to calculate traces of two or more medium-averaged Wilson lines. These are usually dealt with in the literature by invoking the large-Nc limit, but exact calculations have been lacking in many cases. In our work, we show how correlators of multiple Wilson lines appear, and develop a method to calculate them numerically to all orders in Nc. Initially, we focus on the trace of four Wilson lines, which we develop a differential equation for. We will then generalize this calculation to a product of an arbitrary number of Wilson lines, and show how to do the exact calculation numerically, and even analytically in the large-Nc limit. Color sub-leading corrections, that are suppressed with a factor Nc−2 relative to the leading scaling, are calculated explicitly for the four-point correlator and we discuss how to extend this method to the general case. These results are relevant for high-pT jet processes and initial stage physics at the LHC.
The Zb(10610)± and Zb(10650)± are two bottomonium-like structures discovered in the πhb(mP), πΥ(nS) and B∗Bˉ(∗)+h.c. invariant mass spectra, where m={1,2} and n={1,2,3}. Their nature is puzzling due to their charge, which forces its minimal quark content to be bbˉudˉ (bbˉduˉ). Thus, it is necessary to explore four-quark systems in order to understand their inner structure. Additionally, their strong coupling to channels such as πΥ and the closeness of their mass to B∗Bˉ(∗)-thresholds stimulates a molecular interpretation. Within the framework of a constituent quark model which satisfactorily describes a wide range of properties of (non-)conventional hadrons containing heavy quarks, we perform a coupled-channels calculation of the IG(JPC)=1+(1+−) hidden-bottom sector including B(∗)Bˉ∗+h.c., πhb, πΥ and ρηb channels. We analyze the line shapes in the different channels, describing the Υ(5S)→πB(∗)Bˉ(∗) by means of the 3P0 model. Since our description of the line shapes promising, we perform the same coupled-channels calculation for the Zb's with J−−, where J={0,1,2}. This allows us to obtain a fair description of the corresponding line shapes. The study of the analytic structure of the S-matrix suggests that the experimental Zb structures arise as a combination of several poles with JPC=0−−, 1±− and 2−− quantum numbers nearby the BBˉ∗ and B∗Bˉ∗ thresholds.
Domain walls arise in theories where there is spontaneous symmetry breaking of a discrete symmetry such as ZN and are a feature of many BSM models. In this work we consider the possibility of detecting domain walls through their optical effects and specify three different methods of coupling domain walls to the photon. We consider the effects of these couplings in the context of gravitational wave detectors, such as LIGO, and examine the sensitivity of these experiments to domain wall effects. In cases where gravitational wave detectors are not sensitive we examine our results in the context of axion experiments and show how effects of passing domain walls can be detected at interferometers searching for an axion signal.
The statistical significance that characterizes a discrepancy between a measurement and theoretical prediction is usually calculated assuming that the statistical and systematic uncertainties are known. Many types of systematic uncertainties are, however, estimated on the basis of approximate procedures and thus the values of the assigned errors are themselves uncertain. Here the impact of the uncertainty {\it on the assigned uncertainty} is investigated in the context of the muon g−2 anomaly. The significance of the observed discrepancy between the Standard Model prediction of the muon's anomalous magnetic moment and measured values are shown to decrease substantially if the relative uncertainty in the uncertainty assigned to the Standard Model prediction exceeds around 30\%. The reduction in sensitivity increases for higher significance, so that establishing a 5σ effect will require not only small uncertainties but the uncertainties themselves must be estimated accurately to correspond to one standard deviation.
hep-phphysics.data-anEPJ Web Conf.(2022)·9 citations
We estimate the strong coupling constants of charmed and bottom mesons D(s)∗, D(s)1, B(s)∗, and B(s)1 with light vector mesons ρ, ω, K∗, and ϕ within the framework of light-cone QCD sum rules. We compare our estimations to the ones predicted by other approaches.
In the paper, we investigate the moments ⟨ξ2;a1∥;n⟩ of the axial-vector a1(1260)-meson distribution amplitude by using the QCD sum rules approach under the background field theory. By considering the vacuum condensates up to dimension-six and the perturbative part up to next-to-leading order QCD corrections, its first five moments at an initial scale μ0=1GeV are ⟨ξ2;a1∥;2⟩∣μ0=0.223±0.029, ⟨ξ2;a1∥;4⟩∣μ0=0.098±0.008, ⟨ξ2;a1∥;6⟩∣μ0=0.056±0.006, ⟨ξ2;a1∥;8⟩∣μ0=0.039±0.004 and ⟨ξ2;a1∥;10⟩∣μ0=0.028±0.003, respectively. We then construct a light-cone harmonic oscillator model for a1(1260)-meson longitudinal twist-2 distribution amplitude ϕ2;a1∥(x,μ), whose model parameters are fitted by using the least squares method. As an application of ϕ2;a1∥(x,μ), we calculate the transition form factors (TFFs) of D→a1(1260) in large and intermediate momentum transfers by using the QCD light-cone sum rules approach. At the largest recoil point (q2=0), we obtain A(0)=0.130−0.013+0.015, V1(0)=1.898−0.121+0.128, V2(0)=0.228−0.021+0.020, and V0(0)=0.217−0.025+0.023. By applying the extrapolated TFFs to the semi-leptonic decay D0(+)→a1−(0)(1260)ℓ+νℓ, we obtain B(D0→a1−(1260)e+νe)=(5.261−0.639+0.745)×10−5, B(D+→a10(1260)e+νe)=(6.673−0.811+0.947)×10−5, B(D0→a1−(1260)μ+νμ)=(4.732−0.590+0.685)×10−5, B(D+→a10(1260)μ+νμ)=(6.002−0.748+0.796)×10−5.
There is growing evidence that the small weak scale may be related to self-organized criticality. In this regard, we note that if the strange quark were lighter, the QCD phase transition could have been first order, possibly exhibiting quantum critical points at zero temperature as a function of the Higgs vacuum expectation value vh smaller than (but near) the weak scale. We show that these quantum critical points allow a dynamical selection of the observed weak scale, via quantum-dominated stochastic evolutions of the value of vh during eternal inflation. Although the values of vh in different Hubble patches are described by a probability distribution in the multiverse, inflationary quantum dynamics ensures that the peak of the distribution evolves toward critical points (self-organized criticality), driven mainly by the largest Hubble expansion rate there -- the Hubble selection of the universe. To this end, we first explore the quantum critical points of the three-flavor QCD linear sigma model, parametrized by vh at zero temperature, and we present a relaxion model for the weak scale. Among the patches that have reached reheating, it results in a sharp probability distribution of vh near the observed weak scale, which is critical not to the crossover at vh=0 but to the sharp transition at ∼ΛQCD.
We propose an economical model addressing the generation of the Inverse Seesaw mechanism from the spontaneous breaking of a local U(1)B−L, with the Majorana masses of the sterile neutrinos radiatively generated from the dark sector. The field content of the Standard Model is extended by neutral scalars and fermionic singlets, and the gauge group is extended with a U(1)B−L and a discrete Z4 symmetries. Besides dynamically generating the Inverse Seesaw and thus small masses to the active neutrinos, our model offers two possible dark matter candidates, one scalar and one fermionic, stable thanks to a remnant Z2 symmetry. Our model complies with bounds and constraints form dark matter direct detection, invisible Higgs decays and Z′ collider searches for masses of the dark sector at the TeV scale.
Light neutralinos could be copiously produced from the decays of mesons generated in cosmic-ray air showers. These neutralinos can be long-lived particles in the context of R-parity violating (RPV) supersymmetric models, implying that they could be capable of reaching the surface of the earth and decay within the instrumental volume of large neutrino detectors. In this letter, we use atmospheric neutrino data from the Super-Kamiokande experiment to derive novel constraints for the RPV couplings involved in the production of long-lived light neutralinos from the decays of charged D-mesons and kaons. Our results highlight the potential of neutrino detectors to search for long-lived particles, by demonstrating that it is possible to explore regions of parameter space that are not yet constrained by any fixed-target nor collider experiments.
We demonstrate that many Naturalness tests of particle theories discussed in the literature can be reformulated as straightforward algorithmic finetuning assessments in the matching of Wilsonian effective theories above and below particle mass thresholds. Implications of this EFT formulation of Wilsonian Naturalness are discussed for several theories, including the Standard Model, heavy singlet scalar theory, supersymmetry, Grand Unified Theories, twin Higgs theories, and theories of extra dimensions. We argue that the Wilsonian Naturalness algorithm presented here constitutes an unambiguous, a priori, and meaningful test that the Standard Model passes and which "the next good theory" of particle physics is very likely to pass.
Using a new result on the integral involving the product of Bessel functions and associated Laguerre polynomials, published in the mathematical literature some time ago, we present an alternative method for calculating discrete-discrete transition form factors for hydrogen-like atoms. For comparison, an overview is also given of two other commonly used methods.
We investigate the spectrum of linearized excitations of global vortices in 2+1 dimensions. After identifying the existence of localized excitation modes, we compute the decay time scale of the first two and compare the results to the numerical evolution of the full non-linear equations. We show numerically how the interaction of vortices with an external source of radiation or other vortices can excite these modes dynamically. We then simulate the formation of vortices in a phase transition and their interaction with a thermal bath estimating the amplitudes of these modes in each case. These numerical experiments indicate that even though, in principle, vortices are capable of storing a large amount of energy in these internal excitations, this does not seem to happen dynamically. We then explore the evolution of a network of vortices in an expanding (2+1) dimensional background, in particular in a radiation dominated universe. We find that vortices are still excited after the course of the cosmological evolution but again the level of excitation is very small. The extra energy in the vortices in these cosmological simulations never exceeds the 1% level of the total mass of the core of the vortex.
In this work we show that the cosmological lithium problem and the H0 tension could be eased at the same time by allowing variations in the fundamental constants. We compute the primordial abundances of light elements resulting from Big Bang Nucleosynthesis considering the fine structure constant, the Higgs' vacuum expectation value and Newton's constant as free parameters. Using the observational data for abundances, we set constraints on the variations of the fundamental constants. An interpretation of the results in terms of the number of effective relativistic species gives Neff=4.04±0.12. If one extrapolates the fit of {\sffamily Planck} considering this Neff, the value of the inferred Hubble's constant shifts to H0=(71.85±0.77)kms−1Mpc−1, compatible with current direct determinations.
We compute the scaling dimensions of a family of fixed-charge operators at the infrared fixed point of the O(N) model featuring cubic interactions in d=6−ϵ for arbitrary N to leading and subleading order in the charge but to all orders in the couplings. The results are used to analyze the conjectured equivalence with the O(N) model displaying quartic interactions at its ultraviolet fixed point. This is performed by comparing the cubic model scaling dimensions against the known large N results for the quartic model and demonstrating that they match. Our results reinforce the conjectured equivalence and further provide novel information on the finite N physics stemming from the computations in the cubic model just below 6 dimensions.
We report the first-ever calculation of the isovector flavor combination of the chiral-odd twist-3 parton distribution hL(x) for the proton from lattice QCD. We employ gauge configurations with two degenerate light, a strange and a charm quark (Nf=2+1+1) of maximally twisted mass fermions with a clover improvement. The lattice has a spatial extent of 3 fm and lattice spacing of 0.093 fm. The values of the quark masses lead to a pion mass of 260 MeV. We use a source-sink time separation of 1.12 fm to control contamination from excited states. Our calculation is based on the quasi-distribution approach, with three values for the proton momentum: 0.83 GeV, 1.25 GeV, and 1.67 GeV. The lattice data are renormalized non-perturbatively using the RI′ scheme, and the final result for hL(x) is presented in the MS scheme at the scale of 2 GeV. Furthermore, we compute in the same setup the transversity distribution, h1(x), which allows us, in particular, to compare hL(x) to its Wandzura-Wilczek approximation. We also combine results for the isovector and isoscalar flavor combinations to disentangle the individual quark contributions for h1(x) and hL(x), and address the Wandzura-Wilczek approximation in that case as well.
The Future Circular Collider (FCC-ee) offers the unique opportunity of studying the Higgs coupling to the electron, ye, via resonant s-channel production, e+e−→H, in a dedicated run at s=mH. The signature for direct Higgs production is a small rise in cross sections for particular final states, consistent with Higgs decays, over the expectations for their occurrence due to SM background processes involving Z∗,γ∗, or t-channel exchanges. Performing such a measurement is remarkably challenging for four main reasons. First, the low value of the e± mass leads to a tiny ye coupling, and correspondingly small cross section: σee→H∝me2=0.57 fb accounting for initial-state radiation. Second, the e+e− beams must be monochromatized such that their c.m. energy spread is commensurate with the narrow width of the SM Higgs boson, ΓH=4.1 MeV, while keeping large beam luminosities. Third, the Higgs mass must also be known beforehand with a few-MeV accuracy in order to operate the collider at the resonance peak, s=mH. Last but not least, the cross sections of the background processes are many orders-of-magnitude larger than those of the Higgs decay signals. A generator-level study of 11 Higgs decays using a multivariate analysis, exploiting BDTs to discriminate signal and background events, identifies two final states as the most promising ones in terms of statistical significance: H→gg and H→WW∗→ℓν + 2 jets. For a benchmark 4.1-MeV c.m. energy spread (leading to σee→H=0.28 fb) and Lint=10 ab−1, a 1.3σ signal significance can be reached, corresponding to an upper limit on the e± Yukawa at 1.6 times the SM value: ∣ye∣<1.6∣yeSM∣ at 95\% confidence level, per IP per year. Directions for future improvements of the study are outlined.
Thermal monopoles, identified after Abelian projection as magnetic currents wrapping non-trivially around the thermal circle, are studied in Nf=2+1 QCD at the physical point. The distribution in the number of wrappings, which in pure gauge theories points to a condensation temperature coinciding with deconfinement, points in this case to around 275 MeV, almost twice the QCD crossover temperature Tc; similar indications emerge looking for the formation of a percolating current cluster. The possible relation with other non-perturbative phenomena observed above Tc is discussed.
Paleo-detectors are a proposed experimental technique to search for dark matter by reading out the damage tracks caused by nuclear recoils in small samples of natural minerals. Unlike a conventional real-time direct detection experiment, paleo-detectors have been accumulating these tracks for up to a billion years. These long integration times offer a unique possibility: by reading out paleo-detectors of different ages, one can explore the time-variation of signals on megayear to gigayear timescales. We investigate two examples of dark matter substructure that could give rise to such time-varying signals. First, a dark disk through which the Earth would pass every ∼45 Myr, and second, a dark matter subhalo that the Earth encountered during the past gigayear. We demonstrate that paleo-detectors are sensitive to these examples under a wide variety of experimental scenarios, even in the presence of substantial background uncertainties. This paper shows that paleo-detectors may hold the key to unraveling our Galactic history.
We investigate the IR phases of non-supersymmetric (non-SUSY) SO(Nc) gauge theories with NF fermions in the vector representation obtained by perturbing the SUSY theory with anomaly mediated SUSY breaking (AMSB). We find that of the wide variety of phases appearing in the SUSY theory only two survive: for NF<23(Nc−2) the theory confines, breaking the SU(NF) global symmetry to SO(NF), while for 23(Nc−2)<NF<3(Nc−2) the theory flows to a (super)-conformal fixed point. The abelian Coulomb and free magnetic phases do not survive and collapse to the confining phase. We also investigate the behavior of loop operators in order to provide a clear distinction between the confining and screened phases. With the choice of Spin(Nc) for the global structure of the gauge group, we find that the electric Wilson loop indeed obeys an area law, providing one of the first demonstrations of true confinement with chiral symmetry breaking in a non-SUSY theory. We identify monopole condensation as the dynamics underlying confinement. These monopoles arise naturally for NF=Nc−2. The case with smaller number of flavors can be obtained by integrating out flavors, and we confirm numerically that the monopole condensate persists in the presence of AMSB and mass perturbations.
The identification of anomalous overdensities in data - group or collective anomaly detection - is a rich problem with a large number of real world applications. However, it has received relatively little attention in the broader ML community, as compared to point anomalies or other types of single instance outliers. One reason for this is the lack of powerful benchmark datasets. In this paper, we first explain how, after the Nobel-prize winning discovery of the Higgs boson, unsupervised group anomaly detection has become a new frontier of fundamental physics (where the motivation is to find new particles and forces). Then we propose a realistic synthetic benchmark dataset (LHCO2020) for the development of group anomaly detection algorithms. Finally, we compare several existing statistically-sound techniques for unsupervised group anomaly detection, and demonstrate their performance on the LHCO2020 dataset.
↳ stat.MLcs.LGhep-exhep-ph24 citations
* 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.