Thu·Dec 29, 2022Thursday·December 29, 2022

1. 01*

   Exploring unsupervised top tagging using Bayesian inference

   Ezequiel Alvarez🇦🇷 · Manuel Szewc🇺🇸 · Alejandro Szynkman🇦🇷 · Santiago A. Tanco🇦🇷 · Tatiana Tarutina🇦🇷

   Recognizing hadronically decaying top-quark jets in a sample of jets, or even its total fraction in the sample, is an important step in many LHC searches for Standard Model and Beyond Standard Model physics as well. Although there exists outstanding top-tagger algorithms, their construction and their expected performance rely on Montecarlo simulations, which may induce potential biases. For these reasons we develop two simple unsupervised top-tagger algorithms based on performing Bayesian inference on a mixture model. In one of them we use as the observed variable a new geometrically-based observable ${\tilde{A}}_3$, and in the other we consider the more traditional ${\tau }_3/{\tau }_2$ $N$-subjettiness ratio, which yields a better performance. As expected, we find that the unsupervised tagger performance is below existing supervised taggers, reaching expected Area Under Curve AUC $\sim 0.80-0.81$ and accuracies of about 69% $-$ 75% in a full range of sample purity. However, these performances are more robust to possible biases in the Montecarlo that their supervised counterparts. Our findings are a step towards exploring and considering simpler and unbiased taggers.

   hep-phhep-exSciPost Phys.Core(2023)·9 citations
2. 02*

   Neutrino oscillations in Quantum Field Theory

   Sergey Kovalenko🇨🇱 · Fedor Simkovic🇸🇰

   We propose a Quantum Field Theory (QFT) approach to neutrino oscillations in vacuum. The neutrino emission and detection are identified with the charged-current vertices of a single second-order Feynman diagram for the underlying process, enclosing neutrino propagation between these two points. The key point of our approach is the definition of the space-time setup typical for neutrino oscillation experiments, implying macroscopically large but finite volumes of the source and detector separated by a sufficiently large distance $L$. We derive an $L$-dependent master formula for the charged lepton production rate, which provides the QFT basis for the analysis of neutrino oscillations. Our formula depends on the underlying process and is not reducible to the conventional approach resorting to the concept of neutrino oscillation probability, which originates from non-relativistic quantum mechanics (QM). We demonstrate that for some particular choice of the underlying process our QFT formula approximately coincides with the conventional one under some assumptions.

   hep-phhep-exhep-thnucl-th6 citations
3. 03*

   Exploring the molecular scenario of X(4160)

   Ruitian Li🇨🇳 · Dazhuang He🇨🇳 · Xuan Luo🇨🇳 · Hao Sun🇨🇳

   In this work, we investigate the decays of meson $X(4160)$ in the molecular frame. By using an effective lagrangian approach, we calculate the widths of $X(4160)\to J/\psi \varphi$, $D^{\ast }{\bar{D}}^{\ast }$, $D^{\ast }\bar{D}$ and $D\bar{D}$ through the triangle loop mechanism in the molecular scenario. Based on the compositeness condition, the coupling between $X(4160)$ and the $D_s^{\ast }{\bar{D}}_s^{\ast }$ molecular state is determined. The other coupling constants used are determined phenomenologically. The calculation of the decay widths shows that the $D^{\ast }{\bar{D}}^{\ast }$ decay mode has a larger branching ratio. These predictions can be seen as a test for the charmonium assignment of $X(4160)$.

   hep-phEPJC(2024)·0 citations
4. 04*

   Decays of CP-even Higgs bosons $H\to l_i{l}_j$ in a 3-3-1 model with neutral leptons

   H. T. Hung🇻🇳 · A. B. Arbuzov🇷🇺

   The 3-3-1 model with neutral leptons contains four CP-even Higgs bosons when some constraints are imposed on the Higgs potential. Two Higgs bosons of this type are identified with the corresponding ones in the Two-Higgs-Doublet model (2HDM), an other being more massive does not couple with similar particles contained in the Standard Model (SM). The remaining particle is assumed to have no lepton-flavor-violating couplings. The contributions at one-loop order to $\mathrm{\Gamma }(\mathrm{H}\to l_i{l}_j)$$(H\equiv h_1^0,h_2^0,h_3^0)$ come mainly from neutral leptons leading them to depend very strongly on mass of charged Higgs boson, masses and the mixing matrix ($V_{ab}^L$) of the neutral leptons. The numerical investigated results of $\mathrm{\Gamma }(\mathrm{H}\to l_i{l}_j)$ in the spatial regions satisfying the experimental limit of lepton-flavor-violating decays of charged leptons (cLFV) indicate that the signal of SM-like Higgs boson ($\mathrm{\Gamma }(h_1^0\to l_i{l}_j)$) approaches the upper bound of the experimental limit and $\mathrm{\Gamma }(\mathrm{H}\to l_i{l}_j)$ can take large values in the case of $V_{ab}^L=U_{ab}^L(\pi /4,\pi /4,-\pi /4)$ and smaller in the case of $V_{ab}^L=U_{ab}^L(\pi /4,0,0)$. Further, some distinct properties of $\mathrm{\Gamma }(h_2^0\to l_i{l}_j)$ and $\mathrm{\Gamma }(h_3^0\to l_i{l}_j)$ are also discussed.

   hep-ph1 citation
5. 05*

   Non-Holomorphic Soft-Term Contributions to the Higgs-Boson Masses in the Feynman Diagrammatic Approach

   Muhammad Rehman🇵🇰 · Sven Heinemeyer🇪🇸

   We study the effects of non-holomprphic soft SUSY-breaking terms added to the Minimal Supersymmetric Standard Model (MSSM) on the Higgs-boson masses. The calculation of the non-holomorphic contributions is perfromed at the one-loop level in the Feynman diagramatic approach. After generating a FeynArts model file with the help of SARAH, we calculate the renormalized Higgs-boson self-energies at the one-loop level using the FeynArts/FormCalc setup. The results obtained from FeynArts/FormCalc are fed to FeynHiggs to estimate the contributions to the neutral CP-even Higgs-boson masses, $M_{h,H}$, as well as to the charged Higgs-boson mass, $M_{H^{\pm }}$. For the specific set of parameter points that we choose for this study, the non-holomorphic soft-term contributions to the CP-even light Higgs boson mass $M_h$, contrary to claims in the literature, turn out to be very small. For the CP-even heavy Higgs boson mass, $M_H$, as well as for the charged Higgs boson mass, $M_{H^{\pm }}$, the contributions can be substantially larger for some parts of parameter space.

   hep-phPRD(2023)·9 citations
6. 06*

   Predictions for future electron-ion colliders using the Balitsky--Kovchegov equation

   D.Bendova🇨🇿

   This contribution presents the latest predictions for several QCD processes at low-x in the color dipole picture which are of interest for current hadron-hadron and future electron-hadron colliders. The predictions are derived using the solution to the Balitsky-Kovchegov equation for proton and nuclear targets. Two different approaches to the nuclear case are studied: a solution obtained using a newly proposed type of initial condition which represents the initial state of a given nucleus and the solutions based on an initial condition representing a proton coupled to a Glauber-Gribov prescription. The influence from the different energy evolutions of these two approaches are studied in the following photo-nuclear processes: inclusive and diffractive DIS, coherent production of a J/psi meson in ultra-peripheral collisions, and the deeply virtual Compton scattering. By comparison to the available data from HERA and the LHC and to the other models inspired by the Color Glass Condensate framework, it is demonstrated that the future measurements will be useful to discriminate among different approaches to saturation physics. The contribution was presented at the Hot Quarks 2022 - Workshop for young scientists on the physics of ultrarelativistic nucleus-nucleus collisions, Dao House, Colorado, USA, October 11-17 2022.

   hep-ph0 citations
7. 07*

   Neutral pion mass in warm magnetized medium within Linear Sigma Model coupled to Quarks $\left({\text{LSM}}_q\right)$ framework

   Aritra Das🇮🇳 · Najmul Haque🇮🇳

   We study the neutral pion mass in the presence of an external arbitrary magnetic field in the framework of the linear sigma model coupled to quark (LSMq) at finite temperature. In doing so, we have calculated the pion self-energy, constructed the dispersion equation via re-summation, and solved the dispersion relation at zero three momentum limit. In calculating the pion mass, we have included meson self-coupling's thermal and magnetic contribution and approximate chiral order parameter $v_0$. We report that the ${\pi }^0$ mass decreases with the magnetic field and increases with temperature.

   hep-phhep-latnucl-thPRD(2023)·6 citations
8. 08*

   ALPs and Heavy Hadron Chiral Perturbation Theory

   Namit Mahajan🇮🇳

   Axion Like Particles (ALPs) belong to a well motivated class of particles which are part of a more complete UV theory. In this work, we initiate and present the inclusion of such ALPs or the conventional axions in the Heavy Hadron Chiral Perturbation Theory (HHChiPT) in a model independent effective lagrangian way. Such a framework is well suited for studying heavy to heavy quark flavour preserving transitions. For light ALPs, the limits on the ALP couplings (or their combinations) turn out to be independent of ALP mass. Radiative and leptonic decays of heavy vector mesons to corresponding heavy pseudoscalar mesons will be able to provide some of the most stringent constraints on ALPs, particularly the diagonal couplings.

   hep-phPRD(2023)·1 citation
9. 09*

   Exclusive production of quarkonia pairs in collinear factorization framework

   Marat Siddikov🇨🇱 · Ivan Schmidt🇨🇱

   In this paper we analyze the exclusive photoproduction of heavy quarkonia pairs in the collinear factorization framework. We evaluate the amplitude of the process for $J/\psi -{\eta }_c$ quarkonia pair in the leading order of the strong coupling ${\alpha }_s,$ and express it in terms of generalized parton distributions (GPDs) of gluons in the proton. We made numerical estimates in the kinematics of the Electron Ion Collider, and found that in the photoproduction regime, when the virtuality of the photon is much smaller than the quarkonia mass, the cross-section of the process is sufficiently large for experimental studies. We demonstrate that the study of this channel can complement existing studies of gluon GPDs from other channels.

   hep-phPRD(2023)·24 citations
10. 10*

    Emergent phenomena in QCD: The holographic perspective

    Guy F. de Teramond🇨🇷

    A basic understanding of the relevant features of hadron properties from first principles QCD has remained elusive, and should be understood as emergent phenomena which depend critically on the number of dimensions of physical spacetime. These properties include the mechanism of color confinement, the origin of the hadron mass scale, chiral symmetry breaking and the pattern of hadronic bound states. Some of these complex issues have been recently addressed in an effective computational framework of hadron structure based on a semiclassical approximation to light-front QCD, and its holographic embedding in anti-de Sitter (AdS) space. This framework also embodies an underlying superconformal algebraic structure which gives rise to the emergence of a mass scale within the superconformal group: It determines the effective confinement potential of mesons, baryons and tetraquarks. The normalizable zero-mass ground state is identified with the pion which has no baryonic supersymmetric partner, a property which is shared for the lowest meson state in each particle family. This new approach to hadron physics leads to relativistic wave equations, similar in their simplicity to the Schroedinger equation in atomic physics, and provides important insights into the confinement mechanism of QCD.

    hep-phhep-th6 citations
11. 11*

    Strong CP Problem and Symmetric Mass Solution

    Juven Wang🇺🇸

    We propose a novel solution to the Strong CP problem -- to explain why SU(3) strong force has a nearly zero theta angle ${\bar{\theta }}_3\simeq 0$ for the 4d Standard Model (SM). The new ingredient is Symmetric Mass Generation (SMG): symmetry-preserving mass or energy gap can be generated without breaking any symmetry $G$ and without any quadratic mean-field mass deformation as long as $G$ is all perturbative local and nonperturbative global anomaly-free. In our first model, we propose a disordered non-mean-field SMG gap (instead of the ordered Anderson-Higgs induced mass gap) for the $u$ quark (or generally a set of quarks and leptons totally anomaly-free in $G$) generated by multi-fermion interactions or by dynamical disordered mass fields, absorbing ${\bar{\theta }}_3$. Another variant of this first model is the SMG gapping a hypothetical hidden full fourth family of SM fermions. In our second model, we have a chiral SM and mirror SM together to respect the Nielsen-Ninomiya fermion-doubling and a parity-reflection ${\mathbb{Z}}_2^{\mathrm{PR}}$ symmetry at high energy, so the ${\bar{\theta }}_3=0$. Then the SMG lifts only the mirror SM with a large energy gap but leaves the chiral SM at lower energy, which not only "spontaneously" breaks the parity-reflection symmetry maximally but also relates our solution to solve another nonperturbative chiral fermion regularization problem by removing the fermion doubling. The predictive signature of both SMG-based models is that some SM fermions or mirror fermions are highly interacting (beyond the conventional SM Higgs or SM gauge interactions) mediated through hypothetical direct multi-fermion or disordered mass-field interactions.

    hep-phcond-mat.str-elhep-lathep-th+15 citations
12. 12*

    ISAI: Investigating Solar Axion by Iron-57

    Tomonori Ikeda🇯🇵 · Toshihiro Fujii🇯🇵 · Takeshi Go Tsuru🇯🇵 · Yuki Amano🇯🇵 · Kazuho Kayama🇯🇵 · Masamune Matsuda🇯🇵 · Hiromu Iwasaki🇯🇵 · Mizuki Uenomachi🇯🇵 · Kentaro Miuchi🇯🇵 · Yoshiyuki Onuki🇯🇵 · Yoshizumi Inoue🇯🇵 · Akimichi Taketa🇯🇵

    The existence of the axion is a unique solution for the strong CP problem, and the axion is one of the most promising candidates of the dark matter. Investigating Solar Axion by Iron-57 (ISAI) is being prepared as a complemented table-top experiment to confirm the solar axion scenario. Probing an X-ray emission from the nuclear transitions associated with the axion-nucleon coupling is a leading approach. ISAI searches for the monochromatic 14.4 keV X-ray from the first excited state of 57Fe using a state-of-the-art pixelized silicon detector, dubbed XRPIX, under an extremely low-background environment. We highlight scientific objectives, experimental design and the latest status of ISAI.

    ↳ astro-ph.IMastro-ph.GAhep-phphysics.ins-detSciPost Phys.Proc.(2023)·0 citations
13. 13*

    Primordial cosmic complexity and effects of reheating

    Pankaj Saha🇰🇷 · Myeonghun Park🇰🇷

    We study the effects of the reheating phase on the evolution of complexities for the primordial curvature perturbation using the squeezed formalism. We examine the evolution of the out-of-time correlator, the quantum discord, and circuit complexity, starting from the inflationary epoch to the radiation-dominated epoch with different reheating scenarios. We find that for a mode that reenters the horizon after reheating, the effect of a finite reheating epoch on the characteristic \textit{freeze-in} amplitude of these primordial complexities can only be distinguished up to three different classes depending on whether the equation of state parameter: $(i)$ $w_{\mathrm{re}}=1/3$ $(ii)$ $w_{\mathrm{re}}<1/3$, or, (iii) $w_{\mathrm{re}}>1/3$. For reheating with different EOS within these classes, the final amplitude will be the same -- hence, the detailed signature of reheating with a class on the complexity measures will be lost. Taking the central value of the scalar spectral index ($n_s=0.9649$) from Planck and the equation of state during reheating $w_{\mathrm{re}}=0.25$ as benchmark values, we found that the behavior of the complexities for all modes smaller than $1.27\times 10^{16}\mathrm{Mp}{\mathrm{c}}^{-1}$ can be classified as above. However, for the small-scale modes reentering the horizon during reheating, the signature of EOS on the evolution of these two complexities will be embedded in each of the cases separately.

    ↳ astro-ph.COhep-phPRD(2023)·6 citations
14. 14*

    Photon propagator in de Sitter space in the general covariant gauge

    Dražen Glavan🇨🇿 · Tomislav Prokopec🇳🇱

    We consider a free photon field in $D$-dimensional de Sitter space, and construct its propagator in the general covariant gauge. Canonical quantization is employed to define the system starting from the classical theory. This guarantees that the propagator satisfies both the equation of motion and subsidiary conditions descending from gauge invariance and gauge fixing. We first construct the propagator as a sum-over-modes in momentum space, carefully accounting for symmetry properties of the state. We then derive the position space propagator in a covariant representation, that is our main result. Our conclusions disagree with previous results as we find that the position space photon propagator necessarily breaks de Sitter symmetry, except in the exact transverse gauge limit.

    ↳ gr-qchep-phhep-thJHEP(2023)·16 citations
15. 15*

    Equation of state and speed of sound of isospin-asymmetric QCD on the lattice

    Bastian B. Brandt🇩🇪 · Francesca Cuteri🇩🇪 · Gergely Endrodi🇩🇪

    We determine the QCD equation of state at nonzero temperature in the presence of an isospin asymmetry between the light quark chemical potentials on the lattice. Our simulations employ $N_f=2+1$ flavors of dynamical staggered quarks at physical masses, using three different lattice spacings. The main results are based on a two-dimensional spline interpolation of the isospin density, from which all relevant quantities can be obtained analytically. In particular, we present results for the pressure, the interaction measure, the energy and entropy densities, as well as the speed of sound. Remarkably, the latter is found to exceed its ideal gas limit deep in the pion condensed phase, the first account of the violation of this limit in first principles QCD. Finally, we also compute the phase diagram in the temperature -- isospin density plane for the first time. The data for all observables will be useful for the benchmarking of effective theories and low-energy models of QCD and are provided in ancillary files for simple reuse.

    ↳ hep-latastro-ph.HEhep-phnucl-thJHEP(2023)·101 citations
16. 16*

    Non-Gaussian fluctuation dynamics in relativistic fluids

    Xin An🇺🇸 · Gokce Basar🇺🇸 · Mikhail Stephanov🇺🇸 · Ho-Ung Yee🇺🇸

    We consider non-equilibrium evolution of non-Gaussian fluctuations within relativistic hydrodynamics relevant for the QCD critical point search in heavy-ion collision experiments. We rely on the hierarchy of relaxation time scales, which emerges in the hydrodynamic regime near the critical point, to focus on the slowest mode such as the fluctuations of specific entropy, whose equilibrium magnitude, non-Gaussianity and typical relaxation time are increasing as the critical point is approached. We derive evolution equations for the non-Gaussian correlators of this diffusive mode in an arbitrary relativistic hydrodynamic flow. We compare with the simpler case of the stochastic diffusion on a static homogeneous background and identify terms which are specific to the case of the full hydrodynamics with pressure fluctuations and flow.

    ↳ hep-thcond-mat.stat-mechhep-phnucl-thPRC(2023)·29 citations
17. 17*

    General quantum algorithms for Hamiltonian simulation with applications to a non-Abelian lattice gauge theory

    Zohreh Davoudi🇺🇸 · Alexander F. Shaw🇺🇸 · Jesse R. Stryker🇺🇸

    With a focus on universal quantum computing for quantum simulation, and through the example of lattice gauge theories, we introduce rather general quantum algorithms that can efficiently simulate certain classes of interactions consisting of correlated changes in multiple (bosonic and fermionic) quantum numbers with non-trivial functional coefficients. In particular, we analyze diagonalization of Hamiltonian terms using a singular-value decomposition technique, and discuss how the achieved diagonal unitaries in the digitized time-evolution operator can be implemented. The lattice gauge theory studied is the SU(2) gauge theory in 1+1 dimensions coupled to one flavor of staggered fermions, for which a complete quantum-resource analysis within different computational models is presented. The algorithms are shown to be applicable to higher-dimensional theories as well as to other Abelian and non-Abelian gauge theories. The example chosen further demonstrates the importance of adopting efficient theoretical formulations: it is shown that an explicitly gauge-invariant formulation using loop, string, and hadron degrees of freedom simplifies the algorithms and lowers the cost compared with the standard formulations based on angular-momentum as well as the Schwinger-boson degrees of freedom. The loop-string-hadron formulation further retains the non-Abelian gauge symmetry despite the inexactness of the digitized simulation, without the need for costly controlled operations. Such theoretical and algorithmic considerations are likely to be essential in quantumly simulating other complex theories of relevance to nature.

    ↳ hep-lathep-phnucl-thquant-phQuantum(2023)·89 citations
18. 18*

    Bootstrapping Multi-Field Inflation: non-Gaussianities from light scalars revisited

    Dong-Gang Wang🇬🇧 · Guilherme L. Pimentel🇮🇹 · Ana Achúcarro🇳🇱

    Primordial non-Gaussianities from multi-field inflation are a leading target for cosmological observations, because of the possible large correlations generated between long and short distances. These signatures are captured by the local shape of the scalar bispectrum. In this paper, we revisit the nonlinearities of the conversion process from additional light scalars into curvature perturbations during inflation. We provide analytic templates for correlation functions valid at any kinematical configuration, using the cosmological bootstrap as a main computational tool. Our results include the possibility of large breaking of boost symmetry, in the form of small speeds of sound for both the inflaton and the mediators. We consider correlators coming from the tree-level exchange of a massless scalar field. By introducing a late-time cutoff, we identify that the symmetry constraints on the correlators are modified. This leads to anomalous conformal Ward identities, and consequently the bootstrap differential equations acquire a source term that depends on this cutoff. The solutions to the differential equations are scalar seed functions that incorporate these late-time growth effects. Applying weight-shifting operators to auxiliary "seed" functions, we obtain a systematic classification of shapes of non-Gaussianity coming from massless exchange. For theories with de Sitter symmetry, we compare the resulting shapes with the ones obtained via the $\delta N$ formalism, identifying missing contributions away from the squeezed limit. For boost-breaking scenarios, we derive a novel class of shape functions with phenomenologically distinct features. Specifically, the new shape provides a simple extension of equilateral non-Gaussianity: the signal peaks at a geometric configuration controlled by the ratio of the sound speeds of the mediator and the inflaton.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2023)·97 citations
19. 19*

    PBH formation from overdensities in delayed vacuum transitions

    Kiyoharu Kawana🇰🇷 · TaeHun Kim🇰🇷 · Philip Lu🇰🇷

    Primordial black hole (PBH) formation from first-order phase transitions (FOPTs) combines two prevalent elements of beyond the Standard Model physics with wide-ranging consequences. We elaborate on a recently proposed scenario in which inhomogeneities in vacuum energy decay seed the overdensities that collapse to PBHs. In this scenario, the PBH mass is determined by the Hubble mass as in conventional formation scenarios, while its number density is determined by the nucleation dynamics of the FOPT. We present a detailed study of the formation probability including parameter dependencies. In addition, we generate populations in the open mass window as well as for the HSC and OGLE candidate microlensing events. This mechanism inevitably creates PBHs in generic FOPTs, with significant populations produced in slow and moderately strong phase transitions.

    ↳ astro-ph.COhep-phPRD(2023)·94 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.