In this brief note, we confront our results on diffractive photoproduction of J/ψ mesons with the putative gluon shadowing ratio defined as Rg=σ(γA→J/ψA)/σIA., where σIA is the result in impulse approximation. Building on our earlier description of the process in the color-dipole approach, where we took into account the rescattering of ccˉ states only, we demonstrate that the inclusion of ccˉg-Fock states improves the description at small x commonly associated with gluon shadowing.
We present an extension to the Pythia Monte Carlo event generator that enables simulations of collisions between a generic hadron beam on a nuclear target with energy variation in event-by-event basis. This builds upon Pythia's module for heavy ions, Angantyr, as well as previous work on simulating hadron-proton collisions. As such, the extensions in this work are largely technical, except for a rudimentary model for hadronic fluctuations. With hadron-ion simulations, we implement an explicit vector-meson dominance (VMD) model that can be used to simulate interactions of hadronic component of real photons in photo-nuclear collisions. Such processes can be studied in ultra-peripheral heavy-ion collisions and in the future also with the upcoming Electron-Ion Collider. Our work also has applications to hadronic showers, e.g. air showers initiated by high-energy cosmic rays. We first validate the VMD model by comparing to HERA photoproduction data on proton target. Then we apply this to generate events for ultra-peripheral heavy-ion collisions at the LHC and present the results corresponding to the event-selection criteria matching to a recent ATLAS analysis. We find that single-particle multiplicity and rapidity distributions are well in line with the measured ones. We also construct the Fourier coefficients from two-particle correlations for the simulated events and study whether the resulting azimuthal anisotropies are consistent with the ATLAS results.
A method is described for the extrapolation of perturbative expansions in powers of asymptotically small coupling parameters or other variables onto the region of finite variables and even to the variables tending to infinity. The method involves the combination of ideas from renormalization group theory, approximation theory, dynamical theory, and optimal control theory. The extrapolation is realized by means of self-similar factor approximants, whose control parameters can be uniquely defined. The method allows to find the large-variable behavior of sought functions knowing only their small-variable expansions. Convergence and accuracy of the method are illustrated by explicit examples, including the so-called zero-dimensional field theory and anharmonic oscillator. Strong-coupling behavior of Gell-Mann-Low functions in multicomponent field theory, quantum electrodynamics, and quantum chromodynamics is found, being based on their weak-coupling perturbative expansions.
This paper presents a new set of multijet event shape variables introduced to further understand the Mueller-Navelet jet topology. This topology consists of having at least one pair of jets with a very large rapidity separation between them, treating additional jet activity inclusively. This multijet topology is expected to shed light on the radiation pattern that is expected in the high-energy limit of the strong interaction. The paper relies on a Monte Carlo event generator analysis. One set of predictions uses the BFKLex event generator, which is based on Balitsky-Fadin-Kuraev-Lipatov (BFKL) perturbative quantum chromodynamics (pQCD) evolution with a resummation of large logarithms of energy at leading-logarithmic accuracy. The BFKLex predictions are compared with a fixed-order next-to-leading order pQCD calculation using POWHEG matched to the parton shower of PYTHIA8 (NLO+PS), which is the standard for NLO generator predictions at the LHC. We find that both approaches lead to compatible results at current LHC energies, assuming the current experimental constraints for the reconstruction of low transverse momentum jets in ATLAS and CMS. This shows the reliability of the BFKL approach at describing the behavior of the strong interaction in the preasymptotic limit of high center-of-mass energies. Differences between the NLO+PS and the BFKL-based approaches are found when the jet multiplicity is increased or when the minimum transverse momentum of the jets is decreased.
We report progress on the determination and study of quarkonium production within the fragmentation approximation. Our analyses address the moderate and large transverse-momentum regime, where the collinear fragmentation of a single parton is expected to dominate over the short-distance production, directly from the hard scattering, of the constituent (QQˉ) system. Parton fragmentation channels to pseudoscalar and vector quarkonia are built on the basis of non-Relativistic QCD next-to-leading computations, which we use to model initial-scale fragmentation inputs. Thus, a preliminary family of Variable-Flavor Number-Scheme (VFNS) fragmentation functions, named NRFF1.0, are constructed through standard DGLAP evolution. Statistical uncertainties are obtained from a Monte Carlo, replica-like approach embodying missing higher-order uncertainties.
In this paper, we propose an approach based on the theory of an axiomatic S matrix and partially switching on an interaction, which is extremely suitable for describing the phenomenon of oscillations within the framework of quantum field theory. We discuss the relation of the proposed approach with other approaches based on considering of wave packets as asymptotic states or introducing of ``distance- or time-dependent propagators''.
In this paper, we systematically investigate the general dark matter-electron interactions within the framework of effective field theories (EFT). We consider both the non-relativistic (NR) EFT and the relativistic EFT descriptions of the interactions with the spin of dark matter (DM) up to one, i.e., the scalar (ϕ), fermion (χ), and vector (X) DM scenarios. We first collect the leading-order NR EFT operators describing the DM-electron interactions, and construct especially the NR operators for the vector DM case. Next, we consider all possible leading-order relativistic EFT operators including those with a photon field and perform the NR reduction to match them onto the NR EFT. Then we rederive the DM-bound-electron scattering rate within the NR EFT framework and find that the matrix element squared, which is the key input that encodes the DM and atomic information, can be compactly decomposed into three terms. Each term is a product of a DM response function (a0,1,2), which is essentially a factor of Wilson coefficients squared, and its corresponding generalized atomic response function (W0,1,2). Lastly, we employ the electron recoil data from the DM direct detection experiments (including XENON10, XENON1T, and PandaX-4T) to constrain all the non-relativistic and relativistic operators in all three DM scenarios. We set strong bounds on the DM-electron interactions in the sub-GeV region. Particularly, we find that the latest PandaX-4T S2-only data provide stringent constraints on dark matter with a mass greater than approximately 20 MeV, surpassing those from the previous XENON10 and XENON1T experiments.
The prospected sensitivity in αS determination using an event shape observable, ratio of energy correlators at future electron-positron colliders is presented. The study focuses on the collinear region which has suffered from large theoretical and hadronization uncertainty in the past. The ratio effectively reduces the impacts of the uncertainties. With the amount of data that future electron-positron colliders could produce in 1 minute (40 pb−1), a 1--2\% precision of αS could be reached depending on the hadronization uncertainty considered.
Recent analyses by CMS and ATLAS suggest a deviation in the di-photon channel at approximately 95 GeV, alongside a previously observed excess in bbˉ signals at a similar mass by LEP, potentially hinting at a new scalar particle. This study explores this possibility within the framework of the well-established Z3-symmetric Next-to-Minimal Supersymmetric Standard Model. A comprehensive parameter scan was conducted, integrating constraints from dark matter relic density, direct detection experiments, and the properties of the observed 125 GeV Higgs boson. The results demonstrate that the model can accommodate the observed excesses with a singlet-dominated CP-even Higgs boson near 95 GeV. The model accurately predicts signal strengths of the di-photon and bbˉ channels at a level of 1σ. Furthermore, it accounts for the measured dark matter relic abundance through Bino-dominated neutralinos co-annihilation with Wino-like electroweakinos, all while remaining consistent with existing LHC constraints. These findings pave the way for future validation at the high-luminosity LHC and linear colliders, which may offer crucial tests of the model's predictions.
We investigate the 3-3-1 model with neutral leptons (called the 331NL for short) and by that, we will point out that this model can simultaneously explain the lepton flavor violating (LFV) decays of the Z boson Z→eaeb, Standard model-like Higgs boson decay h→ebea, and the charged leptons eb→eaγ consistent with the recent experimental data. In addition, the numerical results show strict relations among these decay rates of Z and h which are predicted by this model. As a result, the decay channels can be determined theoretically if one of them is detected by experiments.
We provide a short review of some aspects of Dark Matter production in non Standard Cosmology. Considering the simplest Higgs portal model as definite particle physics setup, we consider the impact on the parameter space corresponding to the correct relic density, and the complementary experimental constraints, of the presence, during thermal production, of an exotic component dominating the energy density of the Universe. In the second part of the work we will focus on the case that such exotic component satisfies the equation of state of matter and it can produce DM non-thermally.
QCD with the isospin chemical potential, μI, is a useful laboratory to delineate the microphysics in dense QCD. To study the quark-hadron-continuity we use a quark-meson model that interpolates hadronic and quark matter physics at microscopic level. The equation of state is dominated by mesons at low density but taken over by quarks at high density. We extend our previous studies with two-flavors to the three-flavors case to study the impact of the strangeness which may be brought by kaons (K+,K0)=(usˉ,sdˉ) and the UA(1) anomaly. In the normal phase the excitation energies of kaons are reduced by μI in the same way as hyperons in nuclear matter at finite baryon chemical potential. Once pions condense, kaon excitation energies increases as μI does. Moreover, strange quarks become more massive through the UA(1) coupling to the condensed pions. Hence at zero and low temperature the strange hadrons and quarks are highly suppressed. The previous findings in two-flavor models, sound speed peak, negative trace anomaly, gaps insensitve to μI, persist in our three-flavor model and remain consistent with the lattice results to μI∼1 GeV. We discuss the non-perturbative power corrections and quark saturation effects as important ingredients to understand the crossover equations of state measured on the lattice.
We present a comprehensive study of an extended SU(5) grand unified theory (GUT) that incorporates a 45-dimensional Higgs representation to address the shortcomings of the minimal SU(5) GUT, such as the inability to generate realistic fermion mass hierarchies and insufficient proton stability. By considering a hierarchical mass spectrum for the scalar components of the 45-Higgs, we demonstrate that successful gauge coupling unification (GCU) can be achieved. The color octet scalar, color triplet scalar, and color anti-triplet scalar play crucial roles in realizing GCU when their masses are significantly lighter than other components of the 45-Higgs. We focuses on the proton decay channels mediated by the exchange of the color anti-triplet scalar. Assuming that the 45-Higgs couples to all three generations of fermions, we determine the 45-Higgs Yukawa couplings with which the observed fermion mass matrices at low energies are realized. We calculate proton decay rates using the Yukawa couplings obtained from renormalization group evolutions and matching conditions at the GUT scale, thereby exploring the dependence of proton decay rates on model parameters. We find that the p→νπ mode imposes the most stringent constraint on the mass of the color anti-triplet scalar MS1. We also study the correlations between the lower bounds on MS1 derived from different proton decay modes.
We investigate the metastability of scalar fields in quantum field theories at finite temperature, focusing on a detailed understanding of the bounce solution. At finite temperature, the bounce solution depends on two variables: the Euclidean time τ and the spatial radial distance r, and it is periodic in the τ direction. We propose a novel method to determine the bounce that describes transitions in a thermal bath, suitable for numerical calculations. Two types of bounces exist for transitions in the thermal bath: τ-dependent and τ-independent bounces. We apply our method to compute these bounces in several models, including both thin-wall and thick-wall scenarios, to examine their properties. Specifically, we evaluate the critical temperature below which the τ-independent bounce becomes destabilized due to fluctuations, rendering it irrelevant. We demonstrate that in the thick-wall case, the τ-dependent bounce smoothly transitions into the τ-independent one as temperature increases, whereas in the thin-wall case, the transition between the two types of bounces is discontinuous.
This work investigates the phase structure of the non-renormalizable (3+1)-dimensional Nambu-Jona-Lasinio (NJL) model with particular focus on inhomogeneous phases (IPs), where the chiral condensate is non-uniform in space, and the closely related moat regimes, where mesonic dispersion relations favor non-vanishing momenta. We use the mean-field approximation and consider five different regularization schemes including three lattice discretizations. The results within the different regularization schemes are systematically analyzed in order to study the dependence of the IP on the choice of regulatization scheme and regulator value. The IP exhibits a drastic dependence on the chosen regularization scheme rendering any physical interpretation of results on inhomogeneous phases in this model doubtful. In contrast, we find only a mild scheme dependence of the moat regime suggesting that its existence is a consequence of the action of the NJL model and its symmetries and, thus, that it might also exist in QCD.
The search for baryon-number-violating (BNV) nucleon decay is an intriguing probe of new physics beyond the SM in future neutrino experiments with enhanced sensitivity. The dark sector states such as an axion or axion-like particle (ALP) can induce nucleon decays with distinct signature and kinematics from the conventional nucleon decays. In this work, we study the ALP effective field theories (EFTs) with baryon number violation and the impact of light ALP on BNV nucleon decays. We revisit the dimension-8 BNV operators in the extended EFTs with an ALP field a respecting shift symmetry. The low-energy EFT operators with ∣Δ(B−L)∣=2 and ∣Δ(B−L)∣=0 are matched to the baryon chiral perturbation theory. We obtain the effective chiral Lagrangian and the BNV interactions between ALP and baryons/mesons. The ALP interactions lead to two-body baryon decays B→ℓ(orν)a and three-body nucleon decays N→Mℓ(orν)a. We obtain the constraints on the UV scale from the invisible Λ0 decay search at BESIII, the invisible neutron decay search at KamLAND and proton decay search at Super-K. We also show the projections of some other baryon/nucleon decays and present the distinct distributions of kinematic observable.
In this work, we present the first full NLO predictions for the process pp→μ+νμe+νejj at the LHC in a typical tri-boson phase space. The NLO corrections reach 50% at the level of the fiducial cross section and have a very different hierarchy with respect to vector-boson-scattering phase spaces. By comparing the cross section of the full off-shell process with the sum of contributing on-shell electroweak-boson production subchannels, we find that the process is dominated by WWW and WH production, while vector-boson-scattering topologies still play a non-negligible role. In addition, NLO QCD predictions matched to parton shower which are supplemented by approximate electroweak corrections are provided. For the fiducial cross section, the electroweak corrections turn out to be small but the QCD corrections reach 47%. For the inclusive cross section, matching to parton shower affects the predictions by 7%. However, for differential distributions corrections due to the parton shower can be much more sizeable, depending on the region of phase space.
We include the quark to gluon and gluon to quark shock-wave transition operators into the small Bjorken-x evolution equations for helicity in the flavor-singlet channel derived earlier. While such transitions do not affect the large-Nc version of the evolution equations for helicity, the large-Nc&Nf equations are affected. (Nc and Nf are the numbers of quark colors and flavors, respectively.) We derive the corresponding corrected large-Nc&Nf equations for the polarized dipole amplitudes contributing to the flavor-singlet quark and gluon helicity distributions in the double-logarithmic approximation (DLA), resumming powers of αsln2(1/x) with αs the strong coupling constant. We solve these equations iteratively and extract the polarized splitting functions up to four loops. We show that our splitting functions agree with the fixed-order perturbative calculations up to and including the existing three-loops results. Similar to the large-Nc helicity evolution in the shock-wave approach, our large-Nc&Nf small-x splitting functions agree with those obtained in the infrared evolution equations framework up to three loops, but appear to slightly disagree at four loops.
In this paper we continue to develop the homotopy method for solving of the non linear evolution equation for the diffractive production in deep inelastic scattering(DIS). We introduce part of the nonlinear corrections as a first step of this approach. This simplified nonlinear evolution equation is solved analytically taking into account the initial and boundary conditions for the process. At the second step of our approach we demonstrated that the perturbative procedure can be used for the remaining parts of the non-linear corrections. It turns out that these corrections are small and can be estimated in the regular iterative procedure.
Although the electromagnetic and muonic components of extensive air showers have been studied in great detail, no comprehensive simulation study of the neutron component is available. This is related to the complexity of neutron transport processes that is typically not treated in standard simulation tools. In this work we use the Monte Carlo simulation package Fluka to study the production and the transport of neutrons in extensive air showers over the full range of neutron energies, extending down to thermal neutrons. The importance of different neutron production mechanisms and their impact on predicted neutron distributions in energy, lateral distance, atmospheric depth, and arrival time are discussed. In addition, the dependencies of the predictions on the properties of the primary particle are studied. The results are compared to the equivalent distributions of muons, which serve as reference.
In the present work, we analyze several strange as well as non-strange relative hadronic yields obtained in the ultra-relativistic heavy-ion collisions (URHIC) experiments over a wide range of center-of-mass collision energy (sNN). We invoke the formation of a hot and dense hadronic resonance gas (HRG) in the final stage following the URHIC. We use an earlier proposed thermodynamically consistent approach for obtaining the equation of state (EoS) of a HRG. It takes into account an important aspect of the hadronic interaction, viz., the hadronic hard-core repulsion, by assigning hard-core volumes to the hadrons, leading to an excluded volume (EV) type effect. We have invoked the bag model approach to assign hard-core volumes to baryons (antibaryons) while treating mesons to be point particles. We employ ansatz to obtain the dependence of the temperature (\textit{T}) and baryon chemical potential (BCP) of HRG system on the center-of-mass energy in URHIC. We also find strong evidence of a double freeze-out scenario, corresponding to baryons (antibaryons) and mesons, respectively. Strangeness (anti-strangeness) imbalance factor is also seen to play an important role in explaining the ratio of strange hadrons to the non-strange ones. The HRG model can explain the experimental data on various relative hadronic multiplicities quite satisfactorily over a wide range of sNN, ranging from the lowest RHIC energies to the highest LHC energies using one set of model parameters by obtaining the best theoretical fits to the experimental data using the minimum χ2/dof method.
We present a method for constructing global analytical expressions that approximate a function over its entire range. These approximations not only mirror the original function as accurately as desired, but are purposefully created to possess features that the original function lacks. This is particularly useful for functions that lack closed form and are defined by integrals or infinite series. Replacing these definitions with simple analytical expressions enables in-depth qualitative analysis and replaces the current methods of evaluation. We demonstrate this procedure by providing replacements for a variety of pivotal functions in physics and cosmology including the pressure and density of quantum gas, the one-loop correction in thermal field theory, common polylog functions, and the error function.
We present a consistent derivation of the complete Wess-Zumino-Witten interactions of axions, including the counter-term necessary to guarantee the gauge invariance of the Standard Model. By treating the derivative of the axion field as a background gauge field and incorporating auxiliary chiral rotation phases, we ensure consistency in the axion-interaction Lagrangian. This approach allows us to derive basis-independent physical interactions of axions with gauge bosons and vector mesons. As an example, we explore the interaction of a-ω-γ to illustrate the potential for searching for axion-like particles at colliders.
Discovery of the Higgs boson decay to dimuon is anticipated soon based on the current evidence. Precise categorization of the events without affecting the invariant mass shape is crucial in the analysis. Decorrelation of the invariant mass and the output of discriminators (the score of discriminators) is essential for consistent and precise analysis. In this paper we use distance correlation as the additional loss function to achieve the decorrelation for discriminators and examine various analysis methods. The analyses with and without jet substructure variables are presented. Adding jet substructure variables considerably improves the significance of the Higgs to dimuon signal from gluon fusion.
We propose a methodology to infer the reheat temperature (TRH) of the Universe from the collider signal of freezing in dark matter (DM). We demonstrate it for the mono-γ signal at the electron-positron colliders, which indicates to a low-scale TRH, after addressing observed DM abundance, BBN, and other relevant constraints. The method can be used to correlate different reheating dynamics, DM models, and collider signals.
We present numerical studies of the leading non-linear corrections to the DGLAP evolution equations of parton distribution functions (PDFs) resulting from gluon recombination, which reduce the pace of evolution at small momentum fractions x. The non-linear evolution is implemented in the \textsc{HOPPET} and \textsc{xFitter} toolkits and used to carry out fits of proton PDFs using lepton-proton deep inelastic scattering data from HERA, BCDMS and NMC. While we do not find evidence for non-linear effects, we are able to set upper limits for their strength. We also quantify the potential impact of longitudinal structure function measurements at the Electron-Ion Collider and the Large Hadron Electron Collider on future fits.
The detection of Dark Matter (DM) remains a significant challenge in particle physics. This study exploits advanced machine learning models to improve detection capabilities of liquid xenon time projection chamber experiments, utilizing state-of-the-art transformers alongside traditional methods like Multilayer Perceptrons and Convolutional Neural Networks. We evaluate various data representations and find that simplified feature representations, particularly corrected S1 and S2 signals as well as a few shape-related features including the time difference between signals, retain critical information for classification. Our results show that while transformers offer promising performance, simpler models like XGBoost can achieve comparable results with optimal data representations. We also derive exclusion limits in the cross-section versus DM mass parameter space, showing minimal differences between XGBoost and the best performing deep learning models. The comparative analysis of different machine learning approaches provides a valuable reference for future experiments by guiding the choice of models and data representations to maximize detection capabilities.
Obtaining insight into the constituents of dark matter and their interactions with normal matter has inspired a wide range of experimental efforts. Several approaches, particularly those involving searches for ultralight bosonic dark matter (UBDM) fields, involve the use of quantum systems or measurements performed at the limits imposed by quantum mechanics. While a classical treatment of UBDM and its detectors is satisfactory, a fully quantum description would assist in developing future detection strategies. Here, we present an open quantum systems approach that accomplishes this while providing intuition into the quantum nature of the detection process itself. Furthermore, we apply the quantum theory of optical coherence to characterize the statistical properties of the UBDM field. Using representative examples, we show that this theoretical treatment has implications in uncovering signatures of the cosmological production mechanism of the UBDM field and its galactic merger history. By adapting tools from quantum optics, this work will help facilitate the creation of novel methods to extract astrophysically relevant information from correlation measurements.
In recent work, we demonstrated a double-copy relation between inclusive gluon radiation in shock wave collisions of ultrarelativistic nuclei and inclusive graviton radiation in trans-Planckian gravitational shock wave collisions. We compute here the corresponding gravitational shock wave propagators in general relativity and demonstrate that they too obey a double copy relation to gluon shock wave propagators computed previously. These results provide key input in a renormalization group approach towards computing the high frequency radiation spectrum in close black hole encounters.
We show that the effective potentials for the Polyakov loops in finite temperature SU(N) gauge theories obey a certain scaling relation with respect to temperature in the large-N limit. This scaling relation strongly constrains the possible terms in the Polyakov loop effective potentials. Moreover, by using the effective potentials in the presence of imaginary chemical potentials or imaginary angular velocities in several models, we find that phase transitions to Zm-type deconfinement phases (Zm phase) occur, where the eigenvalues of the Polyakov loop are distributed Zm symmetrically. Physical quantities in the Zm phase obey the scaling properties of the effective potential. The models include Yang-Mills (YM) theories, the bosonic BFSS matrix model and N=4 supersymmetric YM theory on S3. Thus, the phase diagrams of large-N gauge theories with imaginary chemical potentials are very rich and the stable Zm phase would be ubiquitous. Monte-Carlo calculations also support this. As a related topic, we discuss the phase diagrams of large-N YM theories with real angular velocities in finite volume spaces.
Using six different parametrizations of the quantum hadrodynamics (one of which is original), I study how different values of the symmetry energy slope (L) affect some microscopic and macroscopic properties of neutron stars, such as the proton fraction, the maximum mass, the radius of the canonical 1.4M⊙ star and its dimensionless tidal parameter Λ. I show that while most quantities present the same qualitative results, the tidal parameter can increase or decrease with the slope, depending on the model. Moreover, special attention is given to the minimum mass that enables the direct URCA process to occur in neutron stars' interiors (MDU). Assuming the weak constraint MDU>1.35M⊙, we see that the maximum value of L that satisfies it lies between 79 and 86 MeV. A range of only 7 MeV. Therefore, MDU is an easy way to impose upper bounds to the slope.
Stochastic gravitational-wave backgrounds can be of either cosmological or astrophysical origin. The detection of an astrophysical stochastic gravitational-wave background with ground-based interferometers is expected in the near future. Perhaps even more excitingly, the detection of stochastic backgrounds of cosmological origin by future ground-based interferometers could reveal invaluable information about the early Universe. From this perspective, the astrophysical background is a {\it foreground} that can prevent the extraction of this information from the data. In this paper, we revisit a time-frequency domain notching procedure previously proposed to remove the astrophysical foreground in the context of next-generation ground-based detectors, but we consider the more realistic scenario where we remove individually detectable signals by taking into account the uncertainty in the estimation of their parameters. We find that time-frequency domain masks can still efficiently remove the astrophysical foreground and suppress it to about 5% of its original level. Further removal of the foreground formed by unresolvable events (in particular, unresolvable binary neutron stars), which is about 10 times larger than the residual foreground from realistic notching, would require detector sensitivity improvements. Therefore, the main limitation in the search for a cosmological background is the unresolvable foreground itself, and not the residual of the notching procedure.
The Pöchl-Teller effective potential mimics an asymptotically de Sitter black hole bounded by an event horizon and a cosmological one. Owing to the benefit of being analytically soluble, the asymptotic quasinormal modes in the modified Pöschl-Teller potential have been extensively explored in the literature by various authors, and the results bear distinct features. Specifically, for small discontinuities placed at the potential's peak, Skakala and Visser showed that the resulting modes lie primarily along the imaginary frequency axis, in line with the numerical results encountered for most black hole metrics. However, it was also suggested that under ultraviolet perturbations, asymptotic modes are expected to lie parallel to the real axis, closely intervening with recent developments on spectral instability. In this work, by numerical and semi-analytical approaches, we aim to resolve the above apparent ambiguity. The numerical scheme is based on an improved version of the matrix method, which is implemented in compactified hyperboloidal coordinates on the Chebyshev grid. It is demonstrated that both asymptotic behaviors indeed agree with the numerical findings, which is somewhat to one's surprise. Specifically, we report the emergence of a novel branch of purely imaginary modes originating from a bifurcation in the asymptotic quasinormal mode spectrum. Moreover, we demonstrate how the bifurcation and asymptotic modes evolve as the discontinuity moves away from the potential's peak, furnishing a dynamic picture as the spectral instability unfolds. It is further argued that they can be partly attributed to the observed parity-dependent deviations occurring for the low-lying perturbed modes of the original Pöschl-Teller effective potential.
In this paper, we study the coupling of the gravity supermultiplet (graviton and gravitino) of minimal N=1 SUGRA following a constructive approach. Firstly, we use the master formulae that follows from considering the scaling behavior of the spinor variables under the little group. Secondly, we derive the 4-point couplings using BFCW. Then, we verify these results for the general 3-point interactions that can be derived using the KLT-type relations, i.e., they can be written as the square of the coupling of the gluons and gluinos. Finally, we consider SUGRA Compton effect for graviton-gravitino. For completeness, we present in the appendix the N=1 Sugra lagrangian in the 2-component Weyl formalism, including the proofs of SUSY and gauge invariance.
An exact analytical solution of the nonlinear boson diffusion equation (NBDE) is presented. It accounts for the time evolution towards the Bose-Einstein equilibrium distribution through inelastic and elastic collisions in case of constant transport coefficients. As a currently interesting application, gluon scattering in relativistic heavy-ion collisions is investigated. An estimate of time-dependent gluon-condensate formation in overoccupied systems through number-conserving elastic scatterings in Pb-Pb collisions at relativistic energies is given.
Rare leptonic and semi-leptonic decays offer an excellent opportunity to test the Standard Model of Particle Physics. These proceedings report on two recent LHCb measurements. The first is an observation of the rare J/ψ→μ+μ−μ+μ− decay and the second is a comprehensive measurement of local and nonlocal contributions to the B0→K∗0μ+μ− decay.
We perform a detailed study of the Υ-, ηb-, and Bc-nucleus systems in momentum space to calculate the bound-state energies and the corresponding coordinate-space radial wave functions. The attractive strong potentials for the meson-nucleus systems are calculated from the Lorentz scalar mass modifications of these mesons in nuclear matter in the local density approximation in the nucleus. The downward shift of the meson masses may be regarded as a signature of partial restoration of chiral symmetry in a nuclear medium applied in the present study in an empirical sense, because the origin of the negative mass shift in this study is not directly related to the chiral symmetry mechanism. Furthermore, as an initial and realistic study, the Bc±-12C bound states are studied for the first time, with the effects of self-consistently calculated Coulomb potentials in 12C (when the Bc± mesons are absent).
Contemporary heavy-ion physics research aims to explore the phase diagram of strongly interacting matter and search for signs of the possible critical endpoint on the QCD phase diagram. Femtoscopy is among the important tools used for this endeavor; there have been indications that combinations of femtoscopic radii parameters (referred to as HBT radii for identical boson pairs) can be related to the system's emission duration. An apparent non-monotonic behavior in their excitation function thus might signal the location of the critical point. In this paper, we show that conclusions drawn from the results obtained with a Gaussian approximation for the pion source shape might be altered if one utilizes a more general Lévy-stable source description. We find that the characteristic size of the pion source function is strongly connected to the shape of the source and its possible power-law behavior. Taking this into account properly changes the observed behavior of the excitation function.
A short review of expansion by regions is presented. It is a well-known strategy to obtain an expansion of a given multiloop Feynman integral in a given limit where some kinematic invariants and/or masses have certain scaling measured in powers of a given small parameter. Prescriptions of this strategy are formulated in a simple geometrical language and are illustrated through simple examples.
Using the gauge-gravity duality, we investigate the fermionic spectroscopy in the D(-1)-D3 brane system. The background geometry of this system described by IIB supergravity includes a black (deconfined) and bubble (confined) D3-brane which corresponds respectively to a deconfined and a confined gauge theory in holography. The charge of the D(-1) brane as the D-instanton gives the gluon condensate in this model. To simplify the holographic setup, we first reduce briefly the ten-dimensional supergravity background produced by D(-1)-D3-branes to an equivalently five-dimensional background. Then the fermionic spectrum in the confined case is obtained by decomposing the fermion with dimensional reduction. In addition, by using the standard method for computing the Green function in the AdS/CFT dictionary, we derive the equations for the fermionic correlation functions and solve them numerically with the infalling boundary condition. Our numerical results in the deconfined case illustrate that the fermionic correlation function as spectral function includes two branches of the dispersion curves whose behavior is very close to the results obtained from the method of hard thermal loop. And the effective mass generated by the medium effect of fermion splits into two values due to the spin-dependent interactions induced by instantons. In the confined case, the holographic correlation function indicates several separated dispersion curves which illustrates consistently the onset mass in the fermionic spectrum we obtained. Therefore, this work in holography demonstrates the instantonic configuration is very influential to the fermion in QCD.
We construct a four-dimensional version of the equation of state (EoS) model NEOS, NEOS-4D, as a function of the temperature and chemical potentials of baryon, electric charge, and strangeness for the hot and dense QCD matter created in relativistic nuclear collisions. This EoS enables multiple conserved charge current evolution in a relativistic fluid. Input from Lattice QCD simulations and a hadron resonance gas model is considered for constructing the equation of state. We investigate its applicability to the relativistic hydrodynamic description of nuclear collisions and present a method for efficient numerical implementation.
The search for a space-time variation of the fundamental constants has been explored over the years to test our physical theories. In this paper, we use the dispersion measure (DM) of fast radio bursts (FRB) combined with type Ia supernovae (SNe) data to investigate a possible redshift evolution of the fine-structure constant (α), considering the runaway dilaton scenario, which predicts αΔα=−γln(1+z), where γ is a constant proportional to the current value of the coupling between the dilaton field and hadronic matter. We derive all the relevant expressions for the DM dependence concerning the fine-structure constant and constrain the parameter γ from measurements of 17 well-localized FRBs and 1048 SNe data from the Pantheon compilation. We also use Monte Carlo simulations to forecast the constraining power of larger samples of FRB measurements for data sets with N=500 and N=1000 points. We found that the uncertainty on γ can be improved by one order of magnitude and that limits on αΔα beyond σ∼10−2 will depend crucially on better control of statistical and systematic uncertainties of upcoming FRB data.
We study detection prospects of a gravitational-wave background (GWB) sourced by SU(2) gauge fields considering all possible observational constraints. More precisely, we consider bounds set by cosmic microwave background measurements, primordial black hole overproduction, as well as backreaction of the gauge fields on the background evolution. Gravitational-waves data from the first three observing runs of the LIGO-Virgo-KAGRA Collaboration show no evidence for a GWB contribution from axion inflation. However, we are able to place conservative constraints on the parameters of the SU(2) inflation with current data. We investigate conditions on the inflationary potential that would lead to a detectable signal that evades astrophysical and cosmological constraints and discuss detection prospects for third generation networks.
We revisit the role of primordial black holes (PBHs) as potential dark matter (DM) candidates, particularly focusing on light asteroid-mass PBHs. These PBHs are expected to emit particles through Hawking evaporation that can generate cosmic rays (CRs), eventually producing other secondary radiations through their propagation in the Milky Way, in addition to prompt emissions. Here, we perform a comprehensive analysis of CR signals resulting from PBH evaporation, incorporating the full CR transport to account for reacceleration and diffusion effects within the Milky Way. In particular, we revisit the e± flux produced by PBHs, using Voyager 1, and study for the first time the diffuse X-ray emission from the up-scattering of Galactic ambient photons due to PBH-produced e± via the inverse Compton effect using XMM-Newton data, as well as the morphological information of the diffuse 511 keV line measured by INTEGRAL/SPI. In doing so, we provide leading constraints on the fraction of DM that can be in form of PBHs in a conservative way, whilst also testing how different assumptions on spin and mass distributions affect our conclusions.
We show that the minimal Weyl-invariant Einstein-Cartan gravity in combination with the Standard Model of particle physics contains just one extra scalar degree of freedom (in addition to the graviton and the Standard Model fields) with the properties of an axion-like particle which can solve the strong CP-problem. The smallness of this particle's mass as well as of the cosmological constant is ensured by tiny values of the gauge coupling constants of the local Lorentz group. The tree value of the Higgs boson mass and that of Majorana leptons (if added to the Standard Model to solve the neutrino mass, baryogenesis and dark matter problems) are very small or vanishing, opening the possibility of their computability in terms of the fundamental parameters of the theory due to nonperturbative effects.
↳ hep-thgr-qchep-phJHEP(2024)·34 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.