HEP Phenomenology·hep-ph
40 papers—22 primary·18 cross-listed·reconstructed*
Recently, there had been renewed interest in limiting the interaction between dark matter particles and known particles. I propose a new way to set upper limits on the coupling of ions or electrons to dark matter particles of arbitrary mass, based on Faraday's Law in a spinning conductor.
Cheuk-Yin Wong🇺🇸 · Andrew V. Koshelkin🇷🇺
We examine the dynamics of quarks and gauge fields in the lowest energy states in the QED and QCD interactions by combining Schwinger's longitudinal confinement in (1+1)D with Polyakov's transverse confinement in (2+1)D in a ``stretch (2+1)D'' flux tube model in (3+1)D. For such QED and QED systems in the flux tube configuration with cylindrical symmetry, we separate out the transverse and longitudinal degrees of freedom, approximate the non-Abelian QCD in the quasi-Abelian approximation, and solve the derived equations to study the collective excitations. We find stable collective QED and QCD excitations showing up as confined QED and QCD mesons, in support of previous theoretical studies and recent observations of the anomalous hypothetical X17 and E38 particles. Future theoretical lattice gauge calculations of QED in (3+1)D with the inclusion of the Schwinger longitudinal confinement mechanism and experimental confirmation of the hypothetical X17 and E38 particles will shed definitive light on quark confinement in the QED interaction in (3+1)D.
Oleksandra Deineka🇩🇪 · Igor Danilkin🇩🇪 · Marc Vanderhaeghen🇩🇪
In this paper, we present a data-driven analysis of the and reactions from threshold up to 4.0 GeV in the invariant mass. For the -wave contribution, we adopt a partial-wave dispersive representation, which is solved using the ansatz. The left-hand cuts are accounted for using the model-independent conformal expansion. The -wave state is described as a Breit-Wigner resonance. The resulting fits are consistent with the data on the invariant mass distribution of the process. Performing an analytic continuation to the complex -plane, we find no evidence of a pole corresponding to the broad resonance reported by the Belle Collaboration. Instead, we find a clear bound state below the threshold at MeV, confirming the previous phenomenological and lattice predictions.
X.H. Mo🇨🇳 · J.Y. Zhang🇨🇳
By virtue of SU(3) flavor symmetry, the effective interaction Hamiltonian is derived in tensor form. The strong and electromagnetic breaking effects are taken into account in a form of "spurion" octet, so that the systematical parametrization of all baryon pair final states is realized on basis of the flavor-singlet principle. As an application, the relative phase between the strong and electromagnetic amplitudes is studied in the light of this scenario. In analyzing the data taken at J/ resonance region in collider, the details of experimental effects, such as energy spread and initial state radiative correction are taken into consideration in order to obtain the correct results.
Si-Qiang Luo🇨🇳 · Tian-Wei Wu🇨🇳 · Ming-Zhu Liu🇨🇳 · Li-Sheng Geng🇨🇳 · Xiang Liu🇨🇳
Inspired by the newly observed state, we systematically investigate the -wave triple-charm molecular states composed of and . We employ the one-boson-exchange model to derive the interactions between and and solve the three-body Schrödinger equations with the Gaussian expansion method. The - mixing and coupled channel effects are carefully assessed in our study. Our results show that the and systems could form bound states, which can be viewed as three-body hadronic molecules. We present not only the binding energies of the three-body bound states, but also the root-mean-square radii of - and -, which further corroborate the molecular nature of these states. These predictions could be tested in the future at LHC or HL-LHC.
Anupam Ghosh🇮🇳 · Partha Konar🇮🇳 · Satyajit Seth🇮🇳
The inert Higgs-doublet model provides a simple framework to accommodate a viable Higgs portal scalar dark matter candidate, together with other heavier scalars of mass 100 GeV or more. We study the effect of next-to-leading order (NLO) QCD corrections in this scenario in the context of the Large Hadron Collider. corrections to the gluon-gluon-Higgs effective coupling have been taken into account in this study wherever appropriate. We find such corrections have a significant impact on various kinematic distributions and reduce scale uncertainties substantially. Fixed order NLO results are matched to the {\sc Pythia8} parton shower (PS) and the di-fatjet signal associated with the missing transverse momentum is analyzed, as this channel has the ability to explore its entire parameter space during the next phase of the LHC run. A closer look at the NLO+PS computation indicates a sizable NLO effect together with a subdued contribution from associated production of the heavy scalar compared to the pair production, thereby leading to a refined analysis strategy during the multivariate analysis of this signal.
Nico Santowsky🇩🇪 · Christian S. Fischer🇩🇪
We study the internal structure of a range of four-quark states with charm quark contributions using a two-body Bethe-Salpeter equation. Thereby, we examine charmonium-like states with hidden charm and quark content , open-charm states with quark content and all-charm states with . In particular we study the internal competition between meson-meson components and diquark-antidiquark components in the wave functions of these states. Our results indicate that the and the are predominantly states and that the recently discovered open-charm state is dominated by an internal component. In both cases the diquark components are negligible. For the all-charm state with as yet unknown quantum numbers we identify candidates in the excitation spectra of and states. Furthermore, our framework serves to provide predictions for further, yet undiscovered open and hidden charm four-quark states.
P. Achenbach (1)🇩🇪 · L. Doria (1)🇩🇪 · M. Battaglieri (2) ((1) Mainz U., Inst. Kernph., (2) Jefferson Lab and INFN, Genoa)🇮🇹
Dark matter is the name assigned to one of the most important contemporary challenges that fundamental physics research is facing. In recent years, the hypothesis that dark matter might be "light" is gaining interest. Following this idea, dark matter particles belong to a new, unexplored dark sector, that is communicating with the Standard Model through one (or more) dark mediator particles. The mass scale of such dark sector particles, i.e. the mediators and the stable dark matter particles, could be comparable to the proton mass or below. Light dark matter would be very difficult to detect with high-energy colliders or with direct detection experiments, so that accelerator-based dark matter searches with smaller, but dedicated experiments are important. The capabilities of high-intensity cw electron and proton beams enable unique opportunities for probing the dark sector. These experimental approaches are complementary to searches for dark matter at the high-energy frontier with the LHC at CERN. The aim of the workshop was to discuss light dark matter searches with national and international experts from experiments as well as from theory.
Francisco J. Botella🇪🇸 · G. C. Branco🇵🇹 · M. N. Rebelo🇵🇹 · J. I. Silva-Marcos🇵🇹 · José Filipe Bastos🇵🇹
We propose a minimal extension of the Standard Model where an up-type vector-like quark, denoted , is introduced and provides a simple solution to the CKM unitarity problem. We adopt the Botella-Chau parametrization in order to extract the quark mixing matrix which contains the three angles of the CKM matrix plus three new angles denoted , , . It is assumed that the mixing of with standard quarks is dominated by . Imposing a recently derived, and much more restrictive, upper-bound on the New Physics contributions to , we find, in the limit of exact dominance where the other extra angles vanish, that is too large. However, if one relaxes the exact dominance limit, there exists a parameter region, where one may obtain in agreement with experiment while maintaining the novel pattern of decays with the heavy quark decaying predominantly to the light quarks and . We also find a reduction in the decay rate of .
Yukinao Akamatsu🇯🇵 · Takahiro Miura🇯🇵
We review recent progress in open quantum system approach to the description of quarkonium in the quark-gluon plasma. A particular emphasis is put on the Lindblad equations for quarkonium and its numerical simulations.
M. M. Altakach🇫🇷 · J. M. Butterworth🇬🇧 · T. Ježo🇩🇪 · M. Klasen🇩🇪 · I. Schienbein🇫🇷
The sensitivity of particle-level fiducial cross section measurements from ATLAS, CMS and LHCb to a leptophobic top-colour model is studied. The model has previously been the subject of resonance searches. Here we compare it directly to state-of-the-art predictions for Standard Model top quark production and also take into account next-to-leading order predictions for the new physics signal. We make use of the CONTUR framework to evaluate the sensitivity of the current measurements, first under the default CONTUR assumption that the measurement and the SM exactly coincide, and then using the full SM theory calculation for at next-to-leading and next-to-next-to-leading order as the background model. We derive exclusion limits, discuss the differences between these approaches, and compare to the limits from resonance searches by ATLAS and CMS.
Danny van Dyk🇩🇪 · Frederik Beaujean🇩🇪 · Thomas Blake🇬🇧 · Christoph Bobeth🇩🇪 · Marzia Bordone🇮🇹 · Katarina Dugic🇩🇪 · Eike Eberhard🇩🇪 · Nico Gubernari🇩🇪 · Elena Graverini🇨🇭 · Martin Jung🇮🇹 · Ahmet Kokulu🇦🇹 · Stephan Kürten🇩🇪 and 8 other authors
EOS is an open-source software for a variety of computational tasks in flavor physics. Its use cases include theory predictions within and beyond the Standard Model of particle physics, Bayesian inference of theory parameters from experimental and theoretical likelihoods, and simulation of pseudo events for a number of signal processes. EOS ensures high-performance computations through a C++ back-end and ease of usability through a Python front-end. To achieve this flexibility, EOS enables the user to select from a variety of implementations of the relevant decay processes and hadronic matrix elements at run time. In this article, we describe the general structure of the software framework and provide basic examples. Further details and in-depth interactive examples are provided as part of the EOS online documentation.
Mingxuan Du🇨🇳 · Rundong Fang🇨🇳 · Zuowei Liu🇨🇳 · Van Que Tran🇨🇳
Long-lived particles that are present in many new physics models beyond the standard model, can be searched for in a number of newly proposed lifetime frontier experiments at the LHC. The signals of the long-lived dark photons can be significantly enhanced in a new dark photon model in which dark photons are copiously produced in the hidden radiation process. We investigate the capability of various lifetime frontier detectors in probing the parameter space of this model, including the far forward detectors FACET and FASER, the far transverse detector MATHUSLA, and the precision timing detector CMS-MTD. We find that the accessible parameter space is significantly enlarged by the hidden radiation process so that FACET, MATHUSLA, and CMS-MTD can probe a much larger parameter space than the so-called minimal model. The parameter space probed by FACET is found to be much larger than FASER, which is largely due to the fact that the former has a larger decay volume and is closer to the interaction point. There also exists some parameter space that can be probed both by the far detectors and by precision timing detectors, so that different experiments can be complementary to each other. A brief overview of the lifetime frontier detectors is also given.
Jinhan Liang🇨🇳 · Zuowei Liu🇨🇳 · Lan Yang🇨🇳
An analysis is given of the Belle II sensitivities and NA64 constraints on the sub-GeV Dirac dark matter that interacts with charged leptons. We consider two different types of interactions between sub-GeV Dirac dark matter and the charged leptons: the EFT operators and the light vector mediators. We compute the Belle II mono-photon sensitivities on sub-GeV dark matter with 50 ab data which are expected to be accumulated in the full Belle II runs. Although the Belle II mono-photon sensitivities on the EFT operators are of similar size as the LEP constraints, Belle II can probe new parameter space of the light vector mediator models that are unexplored by LEP. For both the EFT operators and the light vector mediator models, the Belle II mono-photon sensitivities can be several orders of magnitude stronger than the current dark matter direct detection limits, as well as the white dwarf limits. The light vector mediator can also be directly searched for by reconstructing the invariant mass of its di-lepton decay final states at Belle II, which is found to be complementary to the mono-photon channel. We compute the NA64 constraints on the sub-GeV Dirac dark matter and provide analytic expressions of the dark matter cross section in the Weizsäcker-Williams approximation, for the EFT operators, and for the light vector mediator models. We find that the current NA64 data (with electron-on-target events) provide strong constraints on sub-GeV dark matter. Although the NA64 constraints are found to be about one order of magnitude smaller than the Belle II sensitivities for the EFT operators, NA64 can probe some regions of the parameter space in the light vector mediator models that are beyond the reach of Belle II.
S. Moch (Hamburg U., Inst. Theor. Phys. II)🇩🇪 · B. Ruijl (Zurich, ETH)🇨🇭 · T. Ueda (Seikei U.)🇯🇵 · J.A. M. Vermaseren (Nikhef, Amsterdam)🇳🇱 · A. Vogt (Liverpool U., Dept. Math)🇬🇧
We have computed the four lowest even-N moments of all four splitting functions for the evolution of flavour-singlet parton densities of hadrons at the fourth order in the strong coupling constant alpha_s. The perturbative expansion of these moments, and hence of the splitting functions for momentum fractions x >~ 0.1, is found to be well behaved with relative alpha_s-coefficients of order one and sub-percent effects on the scale derivatives of the quark and gluon distributions at alpha_s ~< 0.2. More intricate computations, including other approaches such as the operator-product expansion, are required to cover the full x-range relevant to LHC analyses. Our results are presented analytically for a general gauge group for detailed checks and validations of such future calculations.
Gábor Bíró🇭🇺 · Bence Tankó-Bartalis🇭🇺 · Gergely Gábor Barnaföldi🇭🇺
Hadronization is a non-perturbative process, which theoretical description can not be deduced from first principles. Modeling hadron formation requires several assumptions and various phenomenological approaches. Utilizing state-of-the-art Computer Vision and Deep Learning algorithms, it is eventually possible to train neural networks to learn non-linear and non-perturbative features of the physical processes. In this study, results of two ResNet networks are presented by investigating global and kinematical quantities, indeed jet- and event-shape variables. The widely used Lund string fragmentation model is applied as a baseline in TeV proton-proton collisions to predict the most relevant observables at further LHC energies.
Maíra Dutra🇨🇦 · Yongcheng Wu🇺🇸
We present EvoEMD, a framework to calculate the evolution of cosmic relics in a Universe with an early matter-dominated (EMD) era. There are mainly two aspects to consider in this regard. First, an EMD era changes the Hubble expansion rate with respect to the standard radiation-dominated (RD) universe. Second, when the EMD era ends, the out-of-equilibrium decay of the dominant matter component may reheat the thermal bath and dilute cosmic relics. We briefly introduce the cosmology with an EMD era, and present how it is implemented in the EvoEMD framework. Users can study the coupled evolution of different interacting species in an EMD or RD universe. Two important cosmic relics are dark matter and a net lepton number. In order to show the capabilities of EvoEMD, we include simple examples of dark matter produced via freeze-out and freeze-in, and also of leptogenesis. Moreover, users can modify the model files in order to explore different new physics scenarios. EvoEMD is hosted on Github at \url{https://github.com/ycwu1030/EvoEMD}.
Ze Long Liu (U. Bern)🇨🇭 · Matthias Neubert (JGU Mainz & Cornell U.)🇩🇪 · Marvin Schnubel🇩🇪 · Xing Wang (JGU Mainz)🇩🇪
Factorization theorems in soft-collinear effective theory at subleading order in power counting involve ``radiative jet functions'', defined in terms of matrix elements of collinear fields with a soft momentum emitted from inside the jet. Of particular importance are the radiative quark jet functions with an external photon or gluon, which arise e.g. in the factorization theorems for the Higgs-boson amplitudes , and induced by light-quark loops. While the photon case has been studied extensively in previous work, we present here a detailed study of the radiative jet function with an external gluon. We calculate this jet function at one- and two-loop order, derive its one-loop anomalous dimension and study its renormalization-group evolution.
Giacomo Cacciapaglia🇫🇷 · Thomas Flacke🇰🇷 · Manuel Kunkel🇩🇪 · Werner Porod🇩🇪
We consider a particular composite Higgs model which contains SU(3) color octet top partners besides the usually considered triplet representations. Moreover, color singlet top partners are present as well which can in principle serve as dark matter candidates. We investigate the LHC phenomenology of these unusual top partners. Some of these states could be confused with gluinos predicted in supersymmetric models at first glance.
Sergey Afonin🇷🇺 · Timofey Solomko🇷🇺
We propose a general method for finding a string-like meson spectrum which is based on a certain condition for the breaking of closed gluon string. A model is constructed that successfully realizes the proposed method. The model is based on the holographic Soft Wall model for QCD and the use of the Wilson confinement criterion. We applied our approach to the vector and scalar cases and obtained numerical predictions for the intercepts of corresponding Regge like radial meson spectra. A good agreement is obtained both with the existing experimental data and with some other known phenomenological approaches. Remarkably, our closed string breaking condition has two branches. We argue that they should correspond to states of opposite parity. The Wilson confinement criterion leads then to a natural mass splitting between parity partners. The constructed model represents thus the first example of bottom-up holographic model in which the effects of chiral symmetry breaking can emerge automatically, i.e., without additional assumptions taken outside of the holographic approach.
Kirill Boguslavski🇦🇹 · Tuomas Lappi🇫🇮 · Sören Schlichting🇩🇪
Motivated by the quark-gluon plasma, we develop a simulation method to obtain the spectral function of (Wilson) fermions non-perturbatively in a non-Abelian gauge theory with large gluon occupation numbers [arXiv:2106.11319]. We apply our method to a non-Abelian plasma close to its non-thermal fixed point, i.e., in a far-from-equilibrium self-similar regime, and find mostly very good agreement with perturbative hard loop (HTL) calculations. For the first time, we extract the full momentum dependence of the damping rate of fermionic collective excitations and compare our results to recent non-perturbative extractions of gluonic spectral functions in two and three spatial dimensions [arXiv:2101.02715, arXiv:1804.01966].
Roberto Fiore🇮🇹 · Laszlo Jenkovszky🇺🇦 · Maryna Oleksiienko🇺🇦
Matter and pressure distribution in hadrons are studied in a dual analytic model of generalized parton distributions with complex Regge trajectories. An original parametrization for pressure distribution in the nucleon is proposed ensuring its stability and compatible with the experimental data from the JLab accelerator.
We investigate gravitational collapse of thick shell of fluid in the isotropic homogeneous universe without radiation described by the Einstein gravity with cosmological constant. We construct analytic solutions of this kind interpolating the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric and the de-Sitter Schwarzschild black hole one by the Gullstrand-Painlevé one. After determining the scale factor for a perfect fluid coexisting with cosmological constant, we determine the orbit of the collapsing shells of fluid from the continuity condition for density and the perpendicular component of pressure at interface. However the continuity condition cannot fix the orbit when there does not exist a perfect fluid inside the shells. In this case we determine the orbit from an equation of state for the fluid consisting a shell near the surface. Finally we confirm that the total energy defined in arXiv:2005.13233 is independent of the given time evolution in this system.
Selim C. Hotinli🇺🇸 · Joel Meyers🇺🇸 · Cynthia Trendafilova🇺🇸 · Daniel Green🇺🇸 · Alexander van Engelen🇺🇸
The effects of gravitational lensing of the cosmic microwave background (CMB) have been measured at high significance with existing data and will be measured even more precisely in future surveys. Reversing the effects of lensing on the observed CMB temperature and polarization maps provides a variety of benefits. Delensed CMB spectra have sharper acoustic peaks and more prominent damping tails, allowing for improved inferences of cosmological parameters that impact those features. Delensing reduces -mode power, aiding the search for primordial gravitational waves and allowing for lower variance reconstruction of lensing and other sources of secondary CMB anisotropies. Lensing-induced power spectrum covariances are reduced by delensing, simplifying analyses and improving constraints on primordial non-Gaussianities. Biases that result from incorrectly modeling nonlinear and baryonic feedback effects on the lensing power spectrum are mitigated by delensing. All of these benefits are possible without any changes to experimental or survey design. We develop a self-consistent, iterative, all-orders treatment of CMB delensing on the curved sky and demonstrate the impact that delensing will have with future surveys.
Dong Zheng🇨🇳 · Zhong-Xiang Wang🇨🇳 · Yi Xing🇨🇳 · Jithesh Vadakkumthani🇮🇳
4FGL J0935.5+0901, a -ray source recently identified as a candidate redback-type millisecond pulsar binary (MSP), shows an interesting feature of having double-peaked emission lines in its optical spectrum. The feature would further suggest the source as a transitional MSP system in the sub-luminous disk state. We have observed the source with \xmm\ and Five-hundred-meter Aperture Spherical radio Telescope (FAST) at X-ray and radio frequencies respectivelyfor further studies. From the X-ray observation, a bimodal count-rate distribution, which is a distinctive feature of the transitional MSP systems, is not detected, while the properties of X-ray variability and power-law spectrum are determined for the source. These results help establish the consistency of it being a redback in the radio pulsar state. However no radio pulsation signals are found in the FAST observation, resulting an upper limit on the flux density of Jy. Implications of these results are discussed.
Yutaro Akahoshi🇯🇵 · Sinya Aoki🇯🇵 · Takumi Doi🇯🇵
In this article, we report the resonance study using the HAL QCD method. We calculate the potential at GeV by a combination of the one-end trick, sequential propagator and covariant approximation averaging (CAA). Thanks to those techniques, we determine the non-local potential at the next-to-next-to-leading order (NLO) of the derivative expansion for the first time and obtain the pole of the S-matrix corresponding to the resonance. We also discuss the comparison between our result and a previous calculation, done by Lüscher's method.
Jun-Sik Yoo🇯🇵 · Shoji Hashimoto🇯🇵 · Hiroshi Ohki🇯🇵
Utilizing the approach recently proposed for the inclusive scattering cross section on the lattice, we compute the differential scattering cross section for the charged current process for various kinematical channels. The simulation is carried out on the 2+1 flavor ensemble with Iwasaki and Domain Wall Fermion action. The lattice results are compared with MINERA result for the equivalent process.
Ali Rida Khalifeh🇪🇸 · Raul Jimenez🇪🇸
The tension between late and early universe probes of today's expansion rate, the Hubble parameter , remains a challenge for the standard model of cosmology CDM. There are many theoretical proposals to remove the tension, with work still needed on that front. However, by looking at new probes of the parameter one can get new insights that might ease the tension. Here, we argue that neutrino oscillations could be such a probe. We expand on previous work and study the full three-flavor neutrino oscillations within the CDM paradigm. We show how the oscillation probabilities evolve differently with redshift for different values of and neutrino mass hierarchies. We also point out how this affects neutrino fluxes which, from their measurements at neutrino telescopes, would determine which value of is probed by this technique, thus establishing the aforementioned aim.
Tsutomu Ishikawa🇯🇵 · Shoji Hashimoto🇯🇵 · Takashi Kaneko🇯🇵
We propose a new method to renormalize lattice operators. The method is based on the technique to compute the spectral sum appearing in the Shifman-Vainshtein-Zakharov QCD sum rule from lattice correlators. The application of this technique to the light quark system is useful for operator renormalization as well as for the test of perturbative QCD and OPE. We determine the renormalization constant of the vector current and discuss extensions to other current operators.
Yuichiro Tada🇯🇵 · Vincent Vennin🇫🇷
We present a generic framework to compute the one-point statistics of cosmological perturbations, when coarse-grained at an arbitrary scale , in the presence of quantum diffusion. Making use of the stochastic- formalism, we show how it can be related to the statistics of the amount of expansion realised until the scale crosses out the Hubble radius. This leads us to explicit formulae for the probability density function (PDF) of the curvature perturbation, the comoving density contrast, and the compaction function. We then apply our formalism to the calculation of the mass distribution of primordial black holes produced in a single-field model containing a "quantum well" (i.e. an exactly flat region in the potential). We confirm that the PDFs feature heavy, exponential tails, with an additional cubic suppression in the case of the curvature perturbation. The large-mass end of the mass distribution is shown to be mostly driven by stochastic-contamination effects, which produce black holes more massive than those naively expected. This work bridges the final gap between the stochastic-inflation formalism and the calculation of the mass distribution of astrophysical objects such as primordial black holes, and opens up various prospects that we finally discuss.
Lattice techniques are the most reliable ones to investigate the QCD phase diagram in the temperature-baryon density (chemical potential) plane. These techniques are, however, well-known to be saddled with a variety of problems at nonzero density. I address here the old question of placing the baryonic (quark) chemical potential on the lattice and point out its important consequences for the current and future experimental searches of the QCD critical point.
Davide Giusti🇩🇪 · Silvano Simula🇮🇹
We present a lattice calculation of the Euclidean position-space windows contributing to the leading-order hadronic vacuum polarization term of the muon anomalous magnetic moment . Short-, intermediate- and long-distance windows are considered in order to isolate different scales sensitive to specific integration ranges of experimental time-like data used in the R-ratio. By adopting the same smooth window function introduced by the RBC and UKQCD Collaborations with width parameter , for the isospin-symmetric, light, quark-connected component we get , and in the short- (SD), intermediate- (W) and long-distance (LD) time regions, respectively, with and . Our results are obtained using the gauge configurations generated by the Extended Twisted Mass Collaboration with dynamical quarks, at three values of the lattice spacing varying from 0.089 to 0.062 fm, at several lattice volumes and with pion masses in the range .
A.Yu. Kotov🇩🇪 · M.P. Lombardo🇮🇹 · A. Trunin🇷🇺
We present the results on topological susceptibility and chiral observables in QCD for temperature range MeV. The lattice simulations are performed with Wilson twisted mass fermions at physical pion, strange and charm masses. In high- region MeV the chiral observables are shown to follow leading order Griffith analyticity, and the topological susceptibility follows a power-law decay as in the instanton dilute gas models. The measured topological susceptibility is used to estimate the mass of QCD axion. The resulting axion mass constraints are in agreement with our previous studies at higher pion masses.
J. Blümlein🇩🇪 · M. Saragnese🇩🇪 · C. Schneider🇦🇹
Hypergeometric structures in single and multiscale Feynman integrals emerge in a wide class of topologies. Using integration-by-parts relations, associated master or scalar integrals have to be calculated. For this purpose it appears useful to devise an automated method which recognizes the respective (partial) differential equations related to the corresponding higher transcendental functions. We solve these equations through associated recursions of the expansion coefficient of the multivalued formal Taylor series. The expansion coefficients can be determined using either the package {\tt Sigma} in the case of linear difference equations or by applying heuristic methods in the case of partial linear difference equations. In the present context a new type of sums occurs, the Hurwitz harmonic sums, and generalized versions of them. The code {\tt HypSeries} transforming classes of differential equations into analytic series expansions is described. Also partial difference equations having rational solutions and rational function solutions of Pochhammer symbols are considered, for which the code {\tt solvePartialLDE} is designed. Generalized hypergeometric functions, Appell-,~Kampé de Fériet-, Horn-, Lauricella-Saran-, Srivasta-, and Exton--type functions are considered. We illustrate the algorithms by examples.
J. M. Yao🇨🇳 · J. Meng🇨🇳 · Y. F. Niu🇨🇳 · P. Ring🇩🇪
Nuclear weak decays provide important probes to fundamental symmetries in nature. A precise description of these processes in atomic nuclei requires comprehensive knowledge on both the strong and weak interactions in the nuclear medium and on the dynamics of quantum many-body systems. In particular, an observation of the hypothetical double beta decay without emission of neutrinos () would unambiguously demonstrate the Majorana nature of neutrinos and the existence of the lepton-number-violation process. It would also provide unique information on the ordering and absolute scale of neutrino masses. The next-generation tonne-scale experiments with sensitivity up to years after a few years of running will probably provide a definite answer to these fundamental questions based on our current knowledge on the nuclear matrix element (NME), the precise determination of which is a challenge to nuclear theory. Beyond-mean-field approaches have been frequently adapted for the study of nuclear structure and decay throughout the nuclear chart for several decades. In this review, we summarize the status of beyond-mean-field calculations of the NMEs of decay assuming the standard mechanism of an exchange of light Majorana neutrinos. The challenges and prospects in the extension and application of beyond-mean-field approaches for decay are discussed.
Eric B. Gregory🇩🇪 · Feng-Kun Guo🇨🇳 · Christoph Hanhart🇩🇪 · Stefan Krieg🇩🇪 · Thomas Luu🇩🇪
In this proceedings we consider several states, namely the , , and , which appear to defy description as simple quark-antiquark pairs. Theoretical input from unitarized chiral perturbation theory suggests they can be understood as emerging from Goldstone-Boson---meson scattering. We present results from an flavor-symmetric lattice QCD simulation at large pion masses suggesting that there exists a bound state in the flavor-sextet representation that cannot emerge for quark-antiquark states, but that appears naturally from the multiquark states. Moreover, we find repulsion in the [15] representation, which establishes the pattern predicted for the interactions of Goldstone bosons with mesons. This suggests these states may have the structure of hadronic molecules.
Gerald V. Dunne🇺🇸 · Max Meynig🇺🇸
We comment that the recent exact six-loop and seven-loop computations of renormalization group functions for the O(N)-symmetric four dimensional phi^4 quantum field theory show hints that the associated large order behavior is dominated by instantons rather than renormalons. This is consistent with a long-standing conjecture that renormalization group functions in the minimal subtraction (MS) renormalization scheme are not sensitive to renormalons.
Jiangyong Jia🇺🇸 · Chun-Jian Zhang🇺🇸
In high-energy heavy-ion collisions, the initial condition of the produced quark-gluon plasma (QGP) and its evolution are sensitive to collective nuclear structure parameters describing the shape and radial profiles of the nuclei. We find a general scaling relation between these parameters and many experimental observables such as elliptic flow, triangular flow, and particle multiplicity distribution. In particular, the ratios of observables between two isobar systems depend only on the differences of these parameters, but not on the details of the final state interactions, hence offering a new way to constrain the QGP initial condition. Using this scaling relation, we show how the structure parameters of Ru and Zr conspire to produce the rich centrality dependences of these ratios, as measured by the STAR Collaboration. Our scaling approach demonstrates that isobar collisions are a precision tool to probe the initial condition of heavy-ion collisions, as well as the collective nuclear structures, including the neutron skin, of the atomic nuclei across energy scales.
Kotaro Murakami🇯🇵 · Yutaro Akahoshi🇯🇵 · Sinya Aoki🇯🇵 · Kenji Sasaki🇯🇵
We study decuplet baryons from meson-baryon interactions, in particular, and baryons from P-wave and interactions, respectively. The interaction potentials are calculated in the HAL QCD method using 3-quark-type source operators at . We use the conventional stochastic estimation of all-to-all propagators combined with the all-mode averaging to reduce statistical fluctuations. We have found that two potentials have quite similar behaviors, suggesting that a mass difference between and comes mainly from a difference of kinematical structure between and , rather than their interactions. The scattering phase shifts calculated from the potentials indicate that and baryons exist as bound states in this lattice setup, whose binding energies are consistent with those obtained from 2-point functions.
D. A. Clarke🇩🇪 · Jishnu Goswami🇩🇪 · F. Karsch🇩🇪 · Anirban Lahiri🇩🇪 · M. Neumann🇩🇪 · C. Schmidt🇩🇪
We report on an ongoing study on the interplay between Roberge-Weiss (RW) and chiral transitions in simulations of (2+1)-flavor QCD with an imaginary chemical potential. We established that the RW endpoint belongs to the 3-, universality class when calculations are done with the Highly Improved Staggered Quark (HISQ) action in the RW plane with physical quark masses. We also have explored a range of quark masses corresponding to pion mass values, ~MeV and found that the transition is consistent with universality class. We argue that observables that were usually used to determine the chiral phase transition temperature, e.g. the chiral condensate and chiral susceptibility, are sensitive to the RW transition and are energy-like observables for the transition, contrary to the magnetic-like (order parameter) behavior at vanishing chemical potential. Moreover the calculations performed at ~MeV also put a stringent constraint for a critical pion mass at zero chemical potential for a possible first-order chiral phase transition.
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