I review the structure of the leading infrared renormalon divergence of the relation between the pole mass and the MS mass of a heavy quark, with applications to the top, bottom and charm quark. That the pole quark mass definition must be abandoned in precision computations is a well-known consequence of the rapidly diverging series. The definitions and physics motivations of several leading renormalon-free, short-distance mass definitions suitable for processes involving nearly on-shell heavy quarks are discussed.
We study the Sivers asymmetry in inelastic J/ψ leptoproduction, ep↑→e+J/ψ+X, within a transverse momentum dependent scheme, the so-called generalized parton model (GPM). The effects of final-state interactions are properly taken into account by employing the color-gauge invariant GPM (CGI-GPM). For the J/ψ formation the non-relativistic QCD (NRQCD) framework is adopted. Predictions for unpolarized cross sections and maximized Sivers asymmetries at EIC energies are given.
We address the modification of open heavy-flavor mesons in a hot medium of light mesons within an effective theory approach consistent with chiral and heavy-quark spin-flavor symmetries and the use of the imaginary time formalism to introduce the non-zero temperature effects to the theory. The unitarized scattering amplitudes, the ground-state self-energies and the corresponding spectral functions are calculated self-consistently. We use the thermal ground-state spectral functions obtained with this methodology to further calculate 1) open-charm meson Euclidean correlators, and 2) off-shell transport coefficients in the hadronic phase.
In the framework of the Inert Higgs Doublet model (IHDM), we have investigated, in the center of mass frame, the neutral Higgs-boson pair production in the presence of an intense and circularly polarized laser field via e+e− annihilation (e+e−→H0A0) at the lowest order. By using the scattering matrix method, we have derived the analytical expression of the differential cross section. The latter is numerically integrated over the solid angle to obtain the total cross section. Then, we have shown how this total cross section depends on the outgoing particles mass for different number of exchanged photons. Next, we have illustrated its variation as a function of the centre of mass energy for different neutral Higgs-boson masses. Finally, we have indicated how it changes as a function of the laser field amplitudes for both different number of exchanged photons and different neutral Higgs-bosons masses.
With the aim of extracting the pion charge radius, we analyse extant precise pion+electron elastic scattering data on Q2∈[0.015,0.144]GeV2 using a method based on interpolation via continued fractions augmented by statistical sampling. The scheme avoids any assumptions on the form of function used for the representation of data and subsequent extrapolation onto Q2≃0. Combining results obtained from the two available data sets, we obtain rπ=0.640(7)fm, a value 2.4σ below today's commonly quoted average. The tension may be relieved by collection and similar analysis of new precise data that densely cover a domain which reaches well below Q2=0.015GeV2. Considering available kaon+electron elastic scattering data sets, our analysis reveals that they contain insufficient information to extract an objective result for the charged-kaon radius, rK. New data with much improved precision, low-Q2 reach and coverage are necessary before a sound result for rK can be recorded.
For complete development of quantum electrodynamics in the presence of a strong external field, the proper understanding of resonant processes and all their peculiarities is essential. We present our attempt to analytically investigate the resonant case of laser-assisted electron-positron pair photoproduction on a nucleus. Due to the presence of external field, the intermediate virtual particle may become real, herewith the second order process in the fine structure constant effectively reduces into the two successive first order processes. All inherent kinematics features were discussed in details and the resonant differential cross section was obtained. We established that the resonant energies of produced particles ambiguously depend on the positron (channel A) or electron (channel B) outgoing angle, and the certain minimal amount of absorbed wave photons are required for resonance to happen. Furthermore, the resonant cross section significantly exceeds the corresponding one in the absence of the external field within the particular kinematic regions and consequently, the considered process can be used qua a marker for probing theoretical predictions of quantum electrodynamics with strong background field.
We discuss the modes B→K(∗)ννˉ in the context of non-standard neutrino interactions that add incoherently to the SM rates. We consider two scenarios: an additional light neutrino; and neutrino lepton flavour violation. We find that an additional light neutrino that interacts with SM fields via a non-universal Z′ can increase RK(∗)ν by up to a factor of two without conflicting with Bs−Bˉs mixing. This model then predicts rates for Bs→τ+τ− up to six times larger than the SM. In the context of neutrino lepton flavour violation mediated by leptoquarks we find that the current experimental upper bounds on RK(∗)ν are already more constraining than direct bounds from Bs→τℓ and B→K(∗)τℓ modes for ℓ=e,μ.
Ω− baryon with sss quarks has been scarcely observed in the experiments so far and has been exploited through many theoretical studies only. Here, an attempt has been made to explore properties of Ω with hypercentral Constituent Quark Model (hCQM) with a linear confining term. The resonance mass spectra has been obtained for 1S-4S, 1P-4P, 1D-3D and 1F-2F respectively. The Regge trajectory has been investigated for the linear nature based on calculated data alongwith the magnetic moment. The present work has been compared with various approaches and known experimental findings.
A Monte Carlo study of identified particle ratio fluctuations at LHC energies is carried out in the frame work of \hij model using the fluctuation variable νdyn. The simulated events for Pb-Pb collisions at sNN = 2.76 and 5.02 TeV and Xe-Xe collisions at sNN = 5.44 TeV are analyzed. From this study, it is observed that the values of [π,K], [p,K] and [π,p] follow the similar trends of energy dependence as observed in the most central collision data by NA49, STAR and ALICE experiments. It is also observed that νdyn for all the three combinations of particles for semi-central and central collisions, the model predicted values of νdyn[A,B] for Pb-Pb collisions at sNN = 2.76 TeV agree fairly well with those observed in ALICE experiment. For peripheral collisions, however, the model predicted values of νdyn[π,K] are somewhat smaller, whereas for [p,K] and [π,p] it predicts larger values as compared to the corresponding experimental values. The possible reasons for the observed differences are discussed. The νdyn values scaled with charged particle density when plotted against ⟨Npart⟩, exhibit a flat behaviour, as expected from the independent particle emission sources. For [p,K] and [π,p] combinations, a departure from the flat trend is, however, observed in central collisions in the case of low pT window when effect of jet quenching or resonances are considered. Furthermore, the study of νdyn[A,B] dependence on particle density for various collision systems (including proton-proton collisions) suggests that at LHC energies νdyn values for a given particle pair is simply a function of charged particle density, irrespective of system size, beam energy and collision centrality.
The behavior of the cumulative number distribution for the charged particles produced in the carbon carbon interactions at 4.2 A GeV/c along with particles with maximum values of the cumulative number in an event too, has been studied.
The scotogenic model is a well motivated scenario that provides both an explanation for neutrino masses and for dark matter. We focus on a real scalar dark matter candidate in this model, produced through standard thermal freeze-out. We analyze the parameter space of the model compatible with the observed dark matter relic abundance, direct and indirect detection searches, limits from lepton flavour violating decays and constraints from the neutrino sector. As the mass differences of the dark matter with the neutral and charged states are found to be small, the new scalars and fermions of the theory will have macroscopic lifetimes, and could thus be potentially detected with long-lived particle signatures at colliders. We find regions in the parameter space to be - partially or fully - consistent with the dark matter relic abundance, and the prediction of a long-lived charged scalar or lightest neutral fermion in the scotogenic scenario, for dark matter masses below 500 GeV. We discuss on the collider phenomenology in some detail.
The branching fraction of the decay τ→K−K0ντ is calculated in the framework of the extended Nambu--Jona-Lasinio model. The contact and vector channels are considered. The contributions to this process of the ρ meson in the ground and first radially excited states are taken into account in the vector channel. The obtained results are in satisfactory agreement with the experimental data. Taking into account the kaon interaction in the final state results in insignificant corrections, which are not beyond the scope of the model uncertainties.
We consider the light Z′ explanation of the muon g−2 anomaly. Even if such a Z′ has no tree-level coupling to electrons, in general one will be induced at loop-level. We show that future beam dump experiments are powerful enough to place stringent constraints on−or discover−a Z′ with loop-suppressed couplings to electrons. Such bounds are avoided only if the Z′ has a large interaction with neutrinos, in which case the scenario will be bounded by ongoing neutrino scattering experiments. The complementarity between beam dump and neutrino scattering experiments therefore indicates that there are good prospects of probing a large part of the Z′ parameter space in the near future.
In this paper, we discuss the potential analysis of the holographic Schwinger effect in the bottom up AdS/QCD model. We study the effect of the magnetic field on the critical field and total potential in finite chemical potential case. By evaluating the critical electric field from the DBI action, one can observe that magnetic field decreases critical electric field Ec. From the results of potential analysis, we find the magnetic field reduces the potential barrier and favor the Schwinger effect which agrees with the results of the critical electric field. Moreover, the Schwinger effect is more obvious when pairs are parallel to the magnetic field than that in perpendicular case in this Einstein-Maxwell-dilaton model.
The production of light (anti-)nuclei and (anti-)hypertriton in a recent collsion system size scan program proposed for the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) is investigated by using the dynamically constrained phase-space coalescence model and the parton and hadron cascade model. The collision system dependence of yield ratios for deuteron to proton, helium-3 to proton, and hypertriton to Λ-hyperon with the corresponding values for antiparticles is predicted. The work presents that for the yield ratios a significant difference exists between (hyper)nuclei and their anti-(hyper)nuclei. Besides, much more suppression for (anti-)hypernuclei than light (anti-)nuclei is present. We further investigate strangeness population factors s3 as a function of atomic mass number A. Our present study can provide a reference for a upcoming collision system scan program at RHIC.
We apply the matrix element method (MEM) to the search for non-resonant Higgs boson pair (HH) production in the channel HH→bbˉWW∗ at the LHC and study the separation between the HH signal and the large irreducible background, which arises from the production of top quark pairs (ttˉ). Our study focuses on events containing two leptons (electrons or muons) in the final state. The separation between signal and background is studied for experimental conditions characteristic for the ATLAS and CMS experiments during LHC Run 2, using the DELPHES fast-simulation package. We find that the ttˉ background can be reduced to a level of 0.26% for a signal efficiency of 35%.
We propose the use of trapped ions for detection of millicharged dark matter. Millicharged particles will scatter off the ions, giving a signal either in individual events or in the overall heating rate of the ions. Ion traps have several properties which make them ideal detectors for such a signal. First, ion traps have demonstrated significant isolation of the ions from the environment, greatly reducing the background heating and event rates. Second, ion traps can have low thresholds for detection of energy deposition, down to ∼neV. Third, since the ions are charged, they naturally have large cross sections for scattering with the millicharged particles, further enhanced by the low velocities of the thermalized millicharges. Despite ion-trap setups being optimized for other goals, we find that existing measurements put new constraints on millicharged dark matter which are many orders of magnitude beyond previous bounds. For example, for a millicharge dark matter mass mQ=10GeV and charge 10−3 of the electron charge, ion traps limit the local density to be nQ≲1cm−3, a factor ∼108 better than current constraints. Future dedicated ion trap experiments could reach even further into unexplored parameter space.
We use the excluded volume Hadron Resonance Gas (HRG) model with the most up-to-date hadron list to calculate ηT/w at low temperatures and at finite baryon densities ρB. This ηT/w is then matched to a QCD-based shear viscosity calculation of the QGP for different profiles of ηT/w across {T,μB} including cross-over and critical point transitions. When compared to ideal hydrodynamic trajectories across {T,μB}, we find that the ηT/w(T,μB) profiles would require initial conditions at much larger baryon density to reach the same freeze-out point.
Recently the LHCb collaboration has observed a new pentaquark state, the Pc(4337)+. Owing to its proximity to the χc0(1S)p, Dˉ∗Λc, DˉΣc and DˉΣc∗ thresholds, this new pentaquark might very well be a meson-baryon bound state. However its spin and parity have not been determined yet and none of the previous possibilities can be ruled out. We briefly explore a few of these options and the consequences they entail in the present manuscript: (i) the Pc(4337)+ might be a χc0(1S)p bound state, (ii) the Pc(4312)+ and Pc(4337)+ might be Dˉ∗Λc and DˉΣc states close to threshold, respectively, where the Breit-Wigner mass might not correspond to the location of the poles, (iii) the locations of the Pc(4312)+ and Pc(4337)+ might be explained in terms of the Dˉ∗Λc-DˉΣc and Dˉ∗Λc-DˉΣc∗ coupled channel dynamics. This last option, though not the most probable explanation, is still potentially compatible with the double peak solution of the Pcs(4459)0 and with what we know of the Pc(4312)+. As a byproduct of the previous explorations, we conjecture the existence of a series of anticharmed meson - antitriplet charmed baryon bound states and calculate their masses.
A detailed reanalysis of the single gluon emission rate at next-to-leading twist is carried out. As was the case in prior efforts, the problem is cast in the framework of deep-inelastic scattering (DIS) of an electron off a large nucleus. The quark produced in the interaction propagates through the remaining nucleus and engenders scattering and gluon radiation, which is calculated in the limit of one re-scattering. This medium induced single gluon emission rate forms the basis of several energy loss calculations in both DIS and heavy-ion collisions. Unlike prior efforts, a complete transverse momentum gradient expansion of the hadronic tensor, including Nc suppressed terms, phase terms and finite gluon momentum fraction terms, ignored previously, is carried out. These terms turn out to be surprisingly large. In contrast to prior efforts, the full next-to-leading twist gluon emission kernel is found to be positive definite and slowly increasing with the exchanged transverse momentum. Phenomenological consequences of these new contributions are discussed.
We consider ZZ production in hadronic collisions and present state-of-the-art predictions in QCD perturbation theory matched to parton showers. Next-to-next-to-leading order corrections to the quark-initiated channel are combined with parton showers using the MiNNLOPS method, while next-to-leading order corrections to the loop-induced gluon fusion channel are matched using the POWHEG method. Their combination, dubbed nNNLO+PS, constitutes the best theoretical description of ZZ events to date. Spin correlations, interferences and off-shell effects are included by calculating the full process pp→ℓ+ℓ−ℓ(′)+ℓ(′)−. We show the crucial impact of higher-order corrections for both quark- and gluon-initiated processes as well as the relevance of the parton shower in certain kinematical regimes. Our predictions are in very good agreement with recent LHC data.
The knowledge of the Higgs potential is crucial for understanding the origin of mass and the thermal history of our Universe. We show how collider measurements and observations of stochastic gravitational wave signals can complement each other to explore the multiform scalar potential in the two Higgs doublet model (2HDM). Accounting for theoretical and current experimental constraints, we analyze the key ingredients in the shape of the Higgs potential triggering the transmutation in phase transition, from the smooth crossover to the strong first-order phase transition (ξc>1), focusing on the barrier formation and the upliftment of the true vacuum. In particular, we observe that the ξc>1 regime is favored for lower scalar masses, rendering strong extra motivation for collider searches. We contrast the dominant collider signals at the HL-LHC (high-luminosity LHC) with observable gravitational wave signals at LISA. We obtain that the HL-LHC will be able to cover a vast range of the ξc>1 parameter space, with scalar decays to heavy fermions (H,A,H±→tt,tb) being the most promising smoking gun signature of a strong first-order electroweak phase transition in the 2HDM.
The vacuum manifold of the standard electroweak model is a three-sphere when one considers homogeneous Higgs field configurations. For inhomogeneous configurations we argue that the vacuum manifold is the Hopf fibered three sphere and that this viewpoint leads to general criteria to detect electroweak monopoles and Z-strings. We extend the Kibble mechanism to study the formation of electroweak monopoles and strings during electroweak symmetry breaking. The distribution of magnetic monopoles produces magnetic fields that have a spectrum Bλ∝λ−2, where λ is a smearing length scale. Even as the magnetic monopoles annihilate due to the confining Z-strings, the magnetic field evolves with the turbulent plasma and may be relevant for cosmological observations.
We explore the sensitivity of directly testing the muon-Higgs coupling at a high-energy muon collider. This is strongly motivated if there exists new physics that is not aligned with the Standard Model Yukawa interactions which are responsible for the fermion mass generation. We illustrate a few such examples for physics beyond the Standard Model. With the accidentally small value of the muon Yukawa coupling and its subtle role in the high-energy production of multiple (vector and Higgs) bosons, we show that it is possible to measure the muon-Higgs coupling to an accuracy of ten percent for a 10 TeV muon collider and a few percent for a 30 TeV machine by utilizing the three boson production, potentially sensitive to a new physics scale about Λ∼30−100 TeV.
Axions are hypothetical particles that may explain the observed dark matter (DM) density and the non-observation of a neutron electric dipole moment. An increasing number of axion laboratory searches are underway worldwide, but these efforts are made difficult by the fact that the axion mass is largely unconstrained. If the axion is generated after inflation there is a unique mass that gives rise to the observed DM abundance; due to nonlinearities and topological defects known as strings, computing this mass accurately has been a challenge for four decades. Recent works, making use of large static lattice simulations, have led to largely disparate predictions for the axion mass, spanning the range from 25 microelectronvolts to over 500 microelectronvolts. In this work we show that adaptive mesh refinement (AMR) simulations are better suited for axion cosmology than the previously-used static lattice simulations because only the string cores require high spatial resolution. Using dedicated AMR simulations we obtain an over three order of magnitude leap in dynamic range and provide evidence that axion strings radiate their energy with a scale-invariant spectrum, to within ∼5% precision, leading to a mass prediction in the range (40,180) microelectronvolts.
With its enormous number of produced neutrinos the LHC is a prime facility to study the behaviour of high-energy neutrinos. In this paper we propose a novel search strategy for identifying neutrino scattering via displaced appearing jets in the high granularity calorimeter (HGCAL) of the CMS endcap in the high luminosity run of the LHC. We demonstrate in a cut-and-count based analysis how the enormous hadronic background can be reduced while keeping most of the neutrino signal. This paper serves as a proof-of-principle study to illustrate the feasibility of the first direct observation of high-energetic neutrinos coming from W decays.
Thermal axion production in the early universe goes through several mass thresholds, and the resulting rate may change dramatically across them. Focusing on the KSVZ and DFSZ frameworks for the invisible QCD axion, we perform a systematic analysis of thermal production across thresholds and provide smooth results for the rate. The QCD phase transition is an obstacle for both classes of models. For the hadronic KSVZ axion, we also deal with production at temperatures around the mass of the heavy-colored fermion charged under the Peccei-Quinn symmetry. Within the DFSZ framework, standard model fermions are charged under this symmetry, and additional thresholds are the heavy Higgs bosons masses and the electroweak phase transition. We investigate the cosmological implications with a specific focus on axion dark radiation quantified by an effective number of neutrino species and explore the discovery reach of future CMB-S4 surveys.
Recent theory progresses in (3+1)D dynamical descriptions of relativistic nuclear collisions at finite baryon density are reviewed. Heavy-ion collisions at different collision energies produce strongly coupled nuclear matter to probe the phase structure of Quantum Chromodynamics (QCD). Dynamical frameworks serve as a quantitative tool to study properties of hot QCD matter and map collisions to the QCD phase diagram. Outstanding challenges are highlighted when confronting theoretical models with the current and forthcoming experimental measurements from the RHIC beam energy scan program.
We investigate the NSVZ relations for N=1 supersymmetric gauge theories with multiple gauge couplings. As examples, we consider MSSM and the flipped SU(5) model, for which they easily reproduce the results for the two-loop β-functions. For N=1 SQCD interacting with the Abelian gauge superfield we demonstrate that the NSVZ-like equation for the Adler D-function follows from the NSVZ relations. Also we derive all-loop equations describing how the NSVZ equations for theories with multiple gauge couplings change under finite renormalizations. They allow describing a continuous set of NSVZ schemes in which the exact NSVZ β-functions are valid for all gauge coupling constants. Very likely, this class includes the HD+MSL scheme, which is obtained if a theory is regularized by Higher covariant Derivatives and divergences are removed by Minimal Subtractions of Logarithms. That is why we also discuss how one can construct the higher derivative regularization for theories with multiple gauge couplings. Presumably, this regularization allows to derive the NSVZ equations for such theories in all loops. In this paper we make the first step of this derivation, namely, the NSVZ equations for theories with multiple gauge couplings are rewritten in a new form which relates the β-functions to the anomalous dimensions of the quantum gauge superfields, of the Faddeev--Popov ghosts, and of the matter superfields. The equivalence of this new form to the original NSVZ relations follows from the extension of the non-renormalization theorem for the triple gauge-ghost vertices, which is also derived in this paper.
We provide a comprehensive summary of concepts from Calabi-Yau motives relevant to the computation of multi-loop Feynman integrals. From this we derive several consequences for multi-loop integrals in general, and we illustrate them on the example of multi-loop banana integrals. For example, we show how Griffiths transversality, known from the theory of variation of mixed Hodge structures, leads quite generically to a set of quadratic relations among maximal cut integrals associated to Calabi-Yau motives. These quadratic relations then naturally lead to a compact expression for l-loop banana integrals in D=2 dimensions in terms of an integral over a period of a Calabi-Yau (l−1)-fold. This new integral representation generalizes in a natural way the known representations for l≤3 involving logarithms with square root arguments and iterated integrals of Eisenstein series. In a second part, we show how the results obtained by some of the authors in earlier work can be extended to dimensional regularization. We present a method to obtain the differential equations for banana integrals with an arbitrary number of loops in dimensional regularization without the need to solve integration-by-parts relations. We also present a compact formula for the leading asymptotics of banana integrals with an arbitrary number of loops in the large momentum limit. This generalizes the novel Γ-class introduced by some of the authors to dimensional regularization and provides a convenient boundary condition to solve the differential equations for the banana integrals. As an application, we present for the first time numerical results for equal-mass banana integrals with up to four loops and up to second order in the dimensional regulator.
A holographic computation of Tc at intermediatecoupling from M-theory dual of thermal QCD-like theories, has been missing in the literature. Filling this gap, we demonstrate a novel UV-IR mixing, (conjecture and provide evidence for) a non-renormalization beyond 1 loop of M−chiral perturbation theory arXiv:2011.04660[hep-th]-compatible deconfinement Temperature, and show equivalence with an Entanglement (as well as Wald) entropy arXiv:0709.2140[hep-th] computation, up to terms Quartic in curvature. We demonstrate a Flavor-Memory (FM) effect in the M-theory uplifts of the gravity duals, wherein the no-braner M-theory uplift retains the "memory" of the flavor D7-branes of the parent type IIB dual in the sense that a specific combination of the aforementioned quartic corrections to the metric components precisely along the compact part of the non-compact four-cycle "wrapped" by the flavor D7-branes, is what determines, e.g., the Einstein-Hilbert action at O(R4). The same linear combination of O(R4) metric corrections, upon matching the phenomenological value of the coupling constant of one of the SU(3) NLO ChPT Lagrangian, is required to have a definite sign. Interestingly, in the decompactification limit of the spatial circle, we derive this, and obtain the values of the relevant O(R4) metric corrections. Further, equivalence with Wald entropy for the black hole at O(R4) imposes a linear constraint on the same linear combination of metric corrections. Remarkably, when evaluating Tc from an entanglement entropy computation in the thermal gravity dual, due to a delicate cancelation between the O(R4) corrections from a subset of the abovementioned metric components, one sees that there are no corrections to Tc at quartic order supporting the conjecture referred to above.
The general formalisms of the q-dual statistics, the Boltzmann-Gibbs statistics, and three versions of the Tsallis statistics known as Tsallis-1, Tsallis-2, and Tsallis-3 statistics have been considered in the canonical ensemble. We have rigorously proved that the probability distribution of the Tsallis-1 statistics is invariant under the uniform energy spectrum translation at a fixed temperature. This invariance demonstrates that the formalism of the Tsallis-1 statistics is consistent with the fundamentals of the equilibrium statistical mechanics. The same results we have obtained for the probability distributions of the Tsallis-3 statistics, Boltzmann-Gibbs statistics, and q-dual statistics. However, we have found that the probability distribution of the Tsallis-2 statistics, the expectation values of which are not consistent with the normalization condition of probabilities, is indeed not invariant under the overall shift in energy as expected.
↳ cond-mat.stat-mechhep-phnucl-thPhysica A: Statistical Mechanics and its Applications(2022)·5 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.