An electron ion collider has been proposed in China (EicC). It is anticipated that the facility would provide polarised electrons, protons and ion beams, in collisions with large centre-of-mass energy. This discussion highlights its potential to address issues that are central to understanding the emergence of mass within the Standard Model, using examples that range from the exploration of light-meson structure, through measurements of near-threshold heavy-quarkonia production, and on to studies of the spectrum of exotic hadrons.
hep-phhep-exhep-latnucl-ex+1Few Body Syst.(2020)·89 citations
Thermal radiation of photons and dileptons from hadronic matter plays an essential role in understanding electromagnetic emission spectra in high-energy heavy-ion collisions. In particular, baryons and anti-baryons have been found to be strong catalysts for electromagnetic radiation, even at collider energies where the baryon chemical potential is small. Here, we conduct a systematic analysis of π- and ω-meson-induced reactions off a large set of baryon states. The interactions are based on effective hadronic Lagrangians where the parameters are quantitatively constrained by empirical information from vacuum decay branchings and scattering data, and gauge invariance is maintained by suitable regularization procedures. The thermal emission rates are computed using kinetic theory but can be directly compared to previous calculations using hadronic many-body theory. The comparison to existing calculations in the literature reveals our newly identified contributions to be rather significant.
We attempt to identify the minimal composite scalar dark matter from strong dynamics with the characteristic mass of order TeV scale. We provide both direct and indirect limits from dark matter direct detections and collider facilities. Compared to a fundamental scalar dark matter, our results show that in the composite scalar dark matter the disappearing resonant mass region, the smaller spin-independent dark matter-nucleon scattering cross section in certain mass region, and the absence at the HL-LHC illustrate how to differentiate these two dark matter models.
We study the event shape variables, transverse energy energy correlation TEEC (cosϕ) and its asymmetry ATEEC (cosϕ) in deep inelastic scattering (DIS) at the electron-proton collider HERA, where ϕ is the angle between two jets defined using a transverse-momentum (kT) jet algorithm. At HERA, jets are defined in the Breit frame, and the leading nontrivial transverse energy energy correlations arise from the 3-jet configurations. With the help of the NLOJET++, these functions are calculated in the leading order (LO) and the next-to-leading order (NLO) approximations in QCD at the electron-proton center-of-mass energy s=314 GeV. We restrict the angular region to −0.8≤cosϕ≤0.8, as the forward- and backward-angular regions require resummed logarithmic corrections, which we have neglected in this work. Following experimental jet-analysis at HERA, we restrict the DIS-variables x, y=Q2/(xs), where Q2=−q2 is the negative of the momentum transfer squared q2, to 0≤x≤1, 0.2≤y≤0.6, and the pseudo-rapidity variable in the laboratory frame (ηlab) to the range −1≤ηlab≤2.5. The TEEC and ATEEC functions are worked out for two ranges in Q2, defined by 5.5GeV2≤Q2≤80GeV2, called the low-Q2-range, and 150GeV2≤Q2≤1000GeV2, called the high-Q2-range. We show the sensitivity of these functions on the parton distribution functions (PDFs), the factorization (μF) and renormalization (μR) scales, and on αs(MZ). Of these the correlations are stable against varying the scale μF and the PDFs, but they do depend on μR. These studies are useful in the analysis of the HERA data, including the determination of αs(MZ) from the shape variables.
Differential equations for the one-loop HQET vertex diagram with arbitrary self-energy insertions and arbitrary residual energies are reduced to the ε form and used to obtain the ε expansion in terms of Goncharov polylogarithms.
A non-perturbative one gluon exchange quark-antiquark interaction is considered to compute flavor dependent U(3) Nambu-Jona-Lasinio (NJL)-type interaction of the form Gij,Γ(ψˉλiΓψ)(ψˉλjΓψ) for i,j=0...8 and Γ=I,iγ5 from one loop polarization process with non degenerate u-d-s quark effective masses. The resulting NJL-type coupling constants in all channels are resolved in the long-wavelength limit and numerical results are presented for different choices of an effective gluon propagator. Leading deviations with respect to a flavor symmetric coupling constant are found to be of the order of (Mf2∗−Mf1∗)n/(Mf2∗+Mf1∗)n, for n=1,2, where Mfi∗ are the effective masses of quarks f1,f2=u,d and s. The scalar channel coupling constants Gij,s can be considerably smaller than pseudoscalar ones. The effect of the flavor-dependence of coupling constants for the masses of pions and kaons may be nearly of the same order of magnitude as the effect of the u,d and s quark mass non-degeneracy. The effect of these coupling constants is also verified for some of the light scalar mesons masses, usually described by quark-antiquark states, and for some observables of the pseudoscalar mesons.
We calculate the rate of collisional decay of the axial charge in an ultrarelativistic electron-positron plasma, also known as the chirality flipping rate. We find that contrary to the existing estimates, the chirality flipping rate appears already in the first order in the fine-structure constant α and is therefore orders of magnitude greater than previously believed. The main channels for the rapid relaxation of the axial charge are the collinear emission of a weakly damped photon and the Compton scattering. The latter contributes to the O(α) result because of the infrared divergence in its cross section, which is regularized on the soft scale ∼eT due to the thermal corrections. Our results are important for the description of the early Universe processes (such as leptogenesis or magnetogenesis) that affect differently left- and right-chiral fermions of the Standard Model, as discussed in more details in the companion Letter.
We discuss information theory as a tool to investigate constrained minimal supersymmetric Standard Model (CMSSM) in the light of observation of Higgs boson at the Large Hadron Collider. The entropy of the Higgs boson using its various detection modes has been constructed as a measure of the information and has been utilized to explore a wide range of CMSSM parameter space after including various experimental constraints from the LEP data, B-physics, electroweak precision observables and relic density of dark matter. According to our study while the lightest neutralino is preferred to have a mass around 1.92 TeV, the gluino mass is estimated to be around 7.44 TeV. The values of CMSSM parameters m0, m1/2, A0 and tanβ correspond to the most preferred scenario are found to be about 6 TeV, 3.6 TeV, −6.9 TeV and 36.8 respectively.
We consider an extension of the Standard Model that was proposed recently by one of the current authors (PQH), which admits magnetic monopoles with a mass of order of a few TeV. We impose, in addition to topological quantization in the SU(2) sector of the model, the Dirac Quantization Condition (DQC) required for consistency of the quantum theory of a charged electron in the presence of the monopole. This leads to the prediction sin2θW=1/4, where θW is the weak mixing angle at the energy scale set by the monopole mass. A leading-order renormalization-group analysis yields the value of sin2θW≃0.231 at the Z-boson mass, as measured by experiment, under suitable conditions on the spectrum of the extra particles in the model.
The inclusive hadroproduction of a Higgs boson and of a jet, featuring large transverse momenta and well separated in rapidity, is proposed as a novel probe channel for the manifestation of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) dynamics. Using the standard BFKL approach, with partial inclusion of next-to-leading order effects, predictions are presented for azimuthal Higgs-jet correlations and other observables, to be possibly compared with experimental analyses at the LHC and with theoretical predictions obtained in different schemes.
The short distance behavior of dark matter (DM) at galaxy scales exhibits several features not explained by the typical cold dark matter (CDM) with velocity-independent cross-section. We discuss a particle physics model with a hidden sector interacting feebly with the visible sector where a dark fermion self-interacts via a dark force with a light dark photon as the mediator. We study coupled Boltzmann equations involving two temperatures, one for each sector. We fit the velocity-dependent DM cross-section to the data from scales of dwarf galaxies to clusters consistent with relic density constraint.
\texttt{SpaceMath v.2.0} with Machine Learning is an extension of the previous version which we implement observables related with LHC Higgs boson data and their projections for the High Luminosity and High Energy Large Hadron Collider. In this version we implemented processes with Flavor-Changing Neutral Currents at tree and one-loop level, namely, i) Radiative decays ℓi→ℓjγ, ii) ℓi→ℓjℓkℓˉk decays (ℓi=τ,μ, ℓj,k=μ,e, with ℓi=ℓj=ℓk) and iii) anomalous magnetic dipole moment of the muon δaμ. \texttt{SpaceMath v.2.0} is able to find allowed regions for free parameters of models with both real and complex singlets and real and complex doublets using the processes previously mentioned within a friendly interface and an intuitive environment in which the user enters the couplings symbolically, sets parameters and execute \texttt{Mathematica} in the traditional way. As result, both tables as plots with values and areas agree with experimental data are generated. We present examples using \texttt{SpaceMath v.2.0} to analyze the free \textit{Two-Higgs Doublet Model of type III} parameter space, step by step, in order to start new users in a fast and efficient way. Finally, we have implemented in this version of \texttt{SpaceMath} algorithms of Machine Learning to generate specific Benchmark Points to be used directly in numerical evaluations of calculations of physical observables.
We show that the Borel representations of tau hadronic spectral function moments based on contour-improved perturbation theory (CIPT) in general differ from those obtained within fixed-order perturbation theory (FOPT) in the presence of IR renormalons in the underlying Adler function. The Borel sums obtained from both types of Borel representations in general differ as well, and the apparently conflicting behavior of the FOPT and CIPT spectral function moment series at intermediate orders, which has been subject to many studies in the past literature, can be understood quantitatively using concrete Borel function models. The difference between the CIPT and FOPT Borel sums, which we call the "asymptotic separation", can be computed analytically for any Borel function model and is proportional to inverse exponential terms in the strong coupling. Even though moments can be designed where the asymptotic separation is strongly suppressed, it is as a matter of principle unavoidable. If the Borel function of the Euclidean Adler function has a sizeable gluon condensate renormalon cut, the asymptotic separation can explain the observed disparity of the CIPT and FOPT spectral function moments at the 5-loop level. The existence of the asymptotic separation implies that the power corrections in the operator product expansion for the spectral function moments in the CIPT expansion approach do not have the commonly assumed analytic standard form.
In soft-collinear effective theory, we analyze the structure of rapidity divergence due to the collinear and soft modes residing in disparate phase spaces. The idea of an effective theory is applied to a system of collinear modes with large rapidity and soft modes with small rapidity. The large-rapidity (collinear) modes are integrated out to obtain the effective theory for the small-rapidity (soft) modes. The full SCET with the collinear and soft modes should be matched onto the soft theory at the rapidity boundary, and the matching procedure becomes exactly the zero-bin subtraction. The large-rapidity region is out of reach for the soft mode, which results in the rapidity divergence. The rapidity divergence in the collinear sector comes from the zero-bin subtraction, which ensures the cancellation of the rapidity divergences from the soft and collinear sectors. In order to treat the rapidity divergence, we construct the rapidity regulators consistently for all the modes. They are generalized by assigning independent rapidity scales for different collinear directions. The soft regulator incorporates the correct directional dependence when the innate collinear directions are not back-to-back, which is discussed in the N-jet operator. As an application, we consider the Sudakov form factor for the back-to-back collinear current and the soft-collinear current, where the soft rapidity regulator for a soft quark is developed. We extend the analysis to the boosted heavy quark sector and exploit the delicacy with the presence of the heavy quark mass. We present the resummed results of large logarithms in the form factors for various currents with the light and the heavy quarks, employing the renormalization group evolution on the renormalization and the rapidity scales.
The open charm strong decay widths and certain ratio of branching fractions of a charmed strange baryon Ξc(2970) are calculated in a 3P0 model. The results are compatible with the latest experimental data. The theoretical ratio of decay branching fractions R=B[Ξc(2970)+→Ξc(2645)0π+]/B[Ξc(2970)+→Ξc′0π+]≈1.0. The spin-parity JP=1/2+ and 3/2+ for different assignments are analyzed. From the results of our calculation, Ξc(2970) can be interpreted as a 2S-wave state with JP(sl)=1/2+(0). The distinguishing between the 2S-wave nρ- and nλ-excitation states and between states with sl=0 and sl=1 and between states with total spin 1/2 and 3/2(sl=1) are also discussed.
In this paper, we will apply the Goldstone equivalence gauge to calculate the 1↔2 processes of a sterile neutrino in the thermal plasma below the standard model (SM) critical temperature Tc≈160 GeV. The sterile neutrino's mass is around the electroweak scale 50 GeV≤mN≤200 GeV, and the acquired thermal averaged effective width Γˉtot is continuous around the cross-over. We will also apply our results to perform a preliminary calculation of the leptogenesis.
We propose the jet charge observable as a novel probe of flavor structure in the nucleon spin program at the Electron Ion Collider (EIC). We show that jet charge measurements can substantially enhance the sensitivity of spin asymmetries to different partonic flavors in the nucleon. This sensitivity can be further improved by constructing the jet charge using only a subset of hadron species (pions or kaons) in the jet. As an example, we use the Sivers asymmetry in back-to-back electron-jet production at the EIC to show that the jet charge can be a unique tool in constraining the Sivers function for different partonic flavors.
High-statistics data on the e+e−→π+π− cross section and the pion vector form factor have been obtained recently by several collaborations. Unfortunately, there are some tensions between different datasets, especially the most precise ones, which have not been resolved so far. Additional independent constraints on the data are therefore of interest. We consider a parametrization-free method of analytic extrapolation proposed recently, which is based on a mixed phase and modulus extremal problem and combines rigorous upper and lower bounds with numerical simulations to account for the statistical distributions of the input and output values. Spacelike data on the form factor and measurements of the modulus in the region (0.65−0.71) GeV are used as input. In previous works, the formalism was applied for extrapolating the form factor to low energies. In the present work, we use it as a stringent and model-independent test of consistency with analyticity and unitarity for the high-statistics data around the ρ resonance. The study reveals some inconsistencies, in particular below the ρ peak the BABAR data are slightly higher than the band of extrapolated values, while above the ρ peak all the data are situated at the lower edge of the band. The implications of the results on the two-pion vacuuum polarization contribution to the anomalous magnetic moment of the muon are briefly discussed.
We study two- and three-baryon systems with two units of charm looking for possible bound states or resonances. All two-baryon interactions are consistently derived from a constituent quark model tuned in the light-flavor hadron phenomenology: spectra and interactions. The presence of the heavy quarks makes the two-body interactions simpler than in the light-flavor sector. Our results show a narrow two-body resonance with quantum numbers (I,JP)=(0,0+). It is located 6.2 MeV below the ΣcΣc threshold and has a width of 4.7 MeV. The foregoing two-body state contributes to generate a NΣcΣc resonance with quantum numbers (I,JP)=(1/2,1/2+) and a separation energy of 0.2 MeV.
Measurements of cosmic neutrinos have a reach potential for providing an insight into fundamental neutrino properties. For this a precise knowledge about an astrophysical environment of cosmic neutrinos propagation is needed. However this is not always possible, and the lack of information can bring about theoretical uncertainties in our physical interpretation of the results of experiments on cosmic neutrino fluxes. We formulate an approach that allows one to quantify the uncertainties using the apparatus of quantum measurement theory. We consider high-energy Dirac neutrinos emitted by some distant source and propagating towards the earth in the interstellar space. It is supposed that neutrinos can meet on their way to the detector at the earth a dense cosmic object serving as a filter that stops active, left-handed neutrinos and letting only sterile, right-handed neutrinos to propagate further. Such a filter mimics the strongest effect on the neutrino flux that can be induced by the cosmic object and that can be missed in the theoretical interpretation of the lab measurements due to the insufficient information about the astrophysical environment of the neutrino propagation. Treating the neutrino interaction with the cosmic object as the first, neutrino-spin measurement, whose result is not recorded, we study its invasive effect on the second, neutrino-flavor measurement in the lab.
We calculate the masses of the QQqˉqˉ (Q=c,b; q=u,d,s) tetraquark states with the aid of heavy diquark-antiquark symmetry (HDAS) and the chromomagnetic interaction (CMI) model. The masses of the highest-spin (J=2) tetraquarks that have only the (QQ)3ˉc(qˉqˉ)3c color structure are related with those of conventional hadrons using HDAS. Thereafter, the masses of their partner states are determined with the mass splittings in the CMI model. Our numerical results reveal that: (i) the lightest ccnˉnˉ (n=u,d) is an I(JP)=0(1+) state around 3929 MeV (53 MeV above the DD∗ threshold) and none of the double-charm tetraquarks are stable; (ii) the stable double-bottom tetraquarks are the lowest 0(1+)bbnˉnˉ around 10488 MeV (≈116 MeV below the BB∗ threshold) and the lowest 1/2(1+)bbnˉsˉ around 10671 MeV (≈20 MeV below the BBs∗/BsB∗ threshold); and (iii) the two lowest bcnˉnˉ tetraquarks, namely the lowest 0(0+) around 7167 MeV and the lowest 0(1+) around 7223 MeV, are near-threshold states. Moreover, we discuss the constraints on the masses of double-heavy hadrons. Specifically, for the lowest nonstrange tetraquarks, we obtain Tcc<3965 MeV, Tbb<10627 MeV, and Tbc<7199 MeV.
A connection between the neutrino and an exotic fermion is described in the general neutrino model. In this model the neutrinos can convert into the new fermion and thus the interaction leads to novel recoil spectrum in the neutrino scattering experiments. We study the general neutrino interaction by evaluating both the tree-level and loop-level contributions to the coherent elastic neutrino-nucleus scattering. We illustrate the scattering by taking the framework of a simplified neutrino model with a Dirac fermion χ and a spin-0 mediator. For the CP phase in the quark sector being 0 and π/2, the detection processes are dominated by the tree-level and loop-level contribution, respectively. We investigate the constraints on the couplings between the mediator and the new particle χ or the quarks by fitting to the COHERENT data. The parameter space with mχ larger than the maximal energy of incoming neutrinos can be also constrained by including the loop-level contribution.
We constrain the lifetime of thermally produced Heavy Neutral Leptons (HNLs) from primordial nucleosynthesis. We show that even a small fraction of mesons present in the primordial plasma leads to the over-production of the primordial helium. This puts an upper bound on the lifetime of HNLs τN<0.02 s for masses mN>mπ (as compared to 0.1 s reported previously). In combination with accelerator searches, this allows us to put a new lower bound on the HNLs masses and defining the "bottom line" for HNL searches at the future Intensity Frontier experiments.
In this article, we report on the computation of the NLO QCD corrections to pp→μ−νˉμe+νebˉbbˉb at the LHC, which is an irreducible background to pp→ttˉH(→bbˉ). This is the first time that a full NLO computation for a 2→8 process with 6 external strongly-interacting partons is made public. No approximations are used, and all off-shell and interference effects are taken into account. Cross sections and differential distributions from the full computation are compared to results obtained by using a double-pole approximation for the top quarks. The difference between the full calculation and the one using the double-pole approximation is in general below 5\% but can reach 10\% in some regions of phase space.
A comologically stable neutral component from a nearly pure SU(2) doublet, with a mass ∼1.1 TeV, is one appealing candidate for dark matter (DM) consistent with all direct dark matter searches. We have explored this possibility in the context of the Minimal Supersymmetric extension of the Standard Model (MSSM), with the Higgsino playing the role of DM, in theories where supersymmetry breaking is transmitted by gravitational interactions at the unification scale M≃2×1016 GeV. We have focussed our work in the search of "light" supersymmetric spectra, which could be at reach of present and/or future colliders, in models with universal and non-universal Higgs and gaugino Majorana masses. The lightest supersymmetric particles of the spectrum are, by construction, two neutralinos and one chargino, almost degenerate, with a mass ∼1.1 TeV, and a mass splitting of a few GeV. Depending on the particular scenario the gluino can be at its experimental mass lower bound ∼ 2.2 TeV; in the squark sector, the lightest stop can be as light as ∼ 1.3 TeV, and the lightest slepton, the right-handed stau, can have a mass as light as 1.2 TeV. The lightest neutralino can be found at the next generation of direct dark matter experimental searches. In the most favorable situation, the gluino, with some specific decay channels, could be found at the next run of the Large Hadron Collider (LHC), and the lightest stop at the High-Luminosity LHC run.
We analyse the basic premises of the `` Froissaron-Maximal Odderon" (FMO) model which was claimed to be ``the only existing model which describes the totality of experimental data ". It is shown that the FMO model suffers from serious theoretical flaws while its quality of the data description is such that the probability that it describes the selected set of data is not satisfactory enough.
The next generation of electron-hadron facilities has the potential for significantly improving our understanding of exotic hadrons. The XYZ states have not been seen in photon-induced reactions so far. Their observation in such processes would provide an independent confirmation of their existence and offer new insights into their internal structure. Based on the known experimental data and the well-established quarkonium and Regge phenomenology, we give estimates for the exclusive cross sections of several XYZ states. For energies near threshold we expect cross sections of few nanobarns for the Zc(3900)+ and upwards of tens of nanobarn for the X(3872), which are well within reach of new facilities.
We revisit the decoupling of neutrinos in the early universe with flavour oscillations. We rederive the quantum kinetic equations which determine the neutrino evolution based on a BBGKY-like hierarchy, and include for the first time the full collision term, with both on- and off-diagonal terms for all relevant reactions. We focus on the case of zero chemical potential and solve these equations numerically. We also develop an approximate scheme based on the adiabatic evolution in the matter basis. In fact, the large difference between the oscillations and cosmological time scales allows to consider averaged flavour oscillations which can speed up the numerical integration by two orders of magnitude, when combined with a direct computation of the differential system Jacobian. The approximate numerical scheme is also useful to gain more insight into the physics of neutrino decoupling. Including the most recent results on plasma thermodynamics QED corrections, we update the effective number of neutrinos to Neff=3.0440. Finally we study the impact of flavour oscillations during neutrino decoupling on the subsequent primordial nucleosynthesis.
Recently, the standard model predictions for the B-meson hadronic decays, Bˉ0→D(∗)+K− and Bˉs0→Ds(∗)+π−, have been updated based on the QCD factorization approach. This improvement sheds light on a novel puzzle in the B-meson hadronic decays: there are mild but universal tensions between data and the predicted branching ratios. Assuming the higher-order QCD corrections are not huge enough to solve the tension, we examine several new physics interpretations of this puzzle. We find that the tension can be partially explained by a left-handed W′ model, which can be compatible with other flavor observables and collider bounds.
The unitarity of the lepton mixing matrix is a critical assumption underlying the standard neutrino-mixing paradigm. However, many models seeking to explain the as-yet-unknown origin of neutrino masses predict deviations from unitarity in the mixing of the active neutrino states. Motivated by the prospect that future experiments may provide a precise measurement of the lepton mixing matrix, we revisit current constraints on unitarity violation from oscillation measurements and project how next-generation experiments will improve our current knowledge. With the next-generation data, the normalizations of all rows and columns of the lepton mixing matrix will be constrained to ≲10\% precision, with the e-row best measured at ≲1\% and the τ-row worst measured at ∼10% precision. The measurements of the mixing matrix elements themselves will be improved on average by a factor of 3. We highlight the complementarity of DUNE, T2HK, JUNO, and IceCube Upgrade for these improvements, as well as the importance of ντ appearance measurements and sterile neutrino searches for tests of leptonic unitarity.
We report an analytical and numerical investigation into the impact of helicity inversion in LHC processes that do not conserve lepton number (L). As a case study, we focus on the production and decay of Majorana neutrinos (N) through on- and off-shell W bosons in the Phenomenological Type I Seesaw model. Using the Monte Carlo event generator \texttt{MadGraph5\_aMC@NLO} in conjunction with the \texttt{HeavyN} model libraries, we perform exact matrix element (ME) computations without the narrow width approximation. Despite helicity inversion appearing explicitly in MEs, we report the absence of helicity suppression of L-violating collider observables for 1→4 and 2→4 processes that are dominated by resonant N production. We attribute this incongruity to the different scalings of 4-momenta and squared 4-momenta in MEs and squared MEs, with exact cancelations occurring in the latter when N goes on-shell in the small-width limit. In off-shell regimes, total suppression / enhancement of L violation can emerge. Implications for other neutrino mass models are discussed.
Recently a novel hadronic state of mass 6.9 GeV, that decays mainly to a pair of charmonia, was observed in LHCb. The data also reveals a broader structure centered around 6490 MeV and suggests another unconfirmed resonance centered at around 7240 MeV, very near to the threshold of two doubly charmed Ξcc baryons. We argue in this note that these exotic hadrons are genuine tetraquarks and not molecules of charmonia. It is conjectured that they are V-baryonium tetraquarks, namely, have an inner structure of a baryonic vertex with a cc diquark attached to it, which is connected by a string to an anti-baryonic vertex with a cˉcˉ anti-diquark. We examine these states as the analogs of the states Ψ(4360) and Y(4630)/Ψ(4660) which are charmonium-like tetraquarks. One way to test these claims is by searching for a significant decay of the state at 7.2 GeV into ΞccΞcc. Such a decay would be the analog of the decay of the state Y(4630) into to ΛcΛc. We further argue that there should be trajectories of both orbital and radial excited states of the X(6900). We predict their masses. It is possible that a few of these states have already been seen by LHCb.
We derive one- and two-loop renormalization group equations (RGEs) of Higgs-R2 inflation. This model has a non-minimal coupling between the Higgs and the Ricci scalar and a Ricci scalar squared term on top of the standard model. The RGEs derived in this paper are valid as long as the energy scale of interest (in the Einstein frame) is below the Planck scale. We also discuss implications to the inflationary predictions and the electroweak vacuum metastability.
Many new physics scenarios contain ultralight scalars, states which are either exactly massless or much lighter than any other massive particle in the model. Axions and majorons constitute well-motivated examples of this type of particle. In this work, we explore the phenomenology of these states in low-energy leptonic observables. After adopting a model independent approach that includes both scalar and pseudoscalar interactions, we briefly discuss the current limits on the diagonal couplings to charged leptons and consider processes in which the ultralight scalar ϕ is directly produced, such as μ→eϕ, or acts as a mediator, as in τ→μμμ. Contributions to the charged leptons magnetic and electric moments are studied as well.
We consider the on-shell mass and wave function renormalization constants ZmOS and Z2OS up to three-loop order allowing for a second non-zero quark mass. We obtain analytic results in terms of harmonic polylogarithms and iterated integrals with the additional letters 1−τ2 and 1−τ2/τ which extends the findings from Ref. [1] where only numerical expressions are presented. Furthermore, we provide terms of order O(ϵ2) and O(ϵ) at two- and three-loop order which are crucial ingrediants for a future four-loop calculation. Compact results for the expansions around the zero-mass, equal-mass and large-mass cases allow for a fast high-precision numerical evaluation.
Alerted by the recent LHCb discovery of exotic hadrons in the range (6.2 -- 6.9) GeV, we present new results for the doubly-hidden scalar heavy (QˉQ)(QQˉ) charm and beauty molecules using the inverse Laplace transform sum rule (LSR) within stability criteria and including the Next-to-Leading Order (NLO) factorized perturbative and ⟨G3⟩ gluon condensate corrections. We also critically revisit and improve existing Lowest Order (LO) QCD spectral sum rules (QSSR) estimates of the (QˉQˉ)(QQ) tetraquarks analogous states. In the example of the anti-scalar-scalar molecule, we separate explicitly the contributions of the factorized and non-factorized contributions to LO of perturbative QCD and to the ⟨αsG2⟩ gluon condensate contributions in order to disprove some criticisms on the (mis)uses of the sum rules for four-quark currents. We also re-emphasize the importance to include PT radiative corrections for heavy quark sum rules in order to justify the (ad hoc) definition and value of the heavy quark mass used frequently at LO in the literature. Our LSR results for tetraquark masses summarized in Table II are compared with the ones from ratio of moments (MOM) at NLO and results from LSR and ratios of MOM at LO (Table IV). The LHCb broad structure around (6.2 --6.7) GeV can be described by the ηcηc, J/ψJ/ψ and χc1χc1 molecules or/and their analogue tetraquark scalar-scalar, axial-axial and vector-vector lowest mass ground states. The peak at (6.8--6.9) GeV can be likely due to a χc0χc0 molecule or/and a pseudoscalar-pseudoscalar tetraquark state. Similar analysis is done for the scalar beauty states whose masses are found to be above the ηbηb and Υ(1S)Υ(1S) thresholds.
We perform a comprehensive study of Milky Way (MW) satellite galaxies to constrain the fundamental properties of dark matter (DM). This analysis fully incorporates inhomogeneities in the spatial distribution and detectability of MW satellites and marginalizes over uncertainties in the mapping between galaxies and DM halos, the properties of the MW system, and the disruption of subhalos by the MW disk. Our results are consistent with the cold, collisionless DM paradigm and yield the strongest cosmological constraints to date on particle models of warm, interacting, and fuzzy dark matter. At 95% confidence, we report limits on (i) the mass of thermal relic warm DM, mWDM>6.5keV (free-streaming length, λfs≲10h−1kpc), (ii) the velocity-independent DM-proton scattering cross section, σ0<8.8×10−29cm2 for a 100MeV DM particle mass (DM-proton coupling, cp≲(0.3GeV)−2), and (iii) the mass of fuzzy DM, mϕ>2.9×10−21eV (de Broglie wavelength, λdB≲0.5kpc). These constraints are complementary to other observational and laboratory constraints on DM properties.
Based on lattice non-relativistic QCD (NRQCD) studies we present results for Bethe-Salpeter amplitudes for Υ(1S), Υ(2S) and Υ(3S) in vacuum as well as in quark-gluon plasma. Our study is based on 2+1 flavor 483×12 lattices generated using the Highly Improved Staggered Quark (HISQ) action and with a pion mass of 161 MeV. At zero temperature the Bethe-Salpeter amplitudes follow the expectations based on non-relativistic potential models. At non-zero temperatures, the interpretation of Bethe-Salpeter amplitudes turns out to be more nuanced, but consistent with our previous lattice QCD study of excited Upsilons in quark-gluon plasma.
The three-body KKKˉ model for the K(1460) resonance is developed on the basis of the Faddeev equations in configuration space. A single-channel approach is using with taking into account the difference of masses of neutral and charged kaons. It is demonstrated that a splitting the mass of the K(1460) resonance takes a place around 1460 MeV according to K0K0Kˉ0, K0K+K− and K+K0Kˉ0, K+K+K− neutral and charged particle configurations, respectively. The calculations are performed with two sets of KK and KKˉ phenomenological potentials, where the latter interaction is considered the same for the isospin singlet and triplet states. The effect of repulsion of the KK interaction on the mass of the KKKˉ system is studied and the effect of the mass polarization is evaluated. The first time the Coulomb interaction for description of the K(1460) resonance is considered. The mass splitting in the K(1460) resonances is evaluated to be in range of 10 MeV with taking into account the Coulomb force. The three-body model with the KKˉ potential, which has the different strength of the isospin singlet and triplet parts that are related by the condition of obtaining a quasi-bound three-body state is also considered. Our results are in reasonable agreement with the experimental mass of the K(1460) resonance.
Grand unification groups (GUTs) are constructed from SO(32) heterotic string via Z12−I orbifold compactification. So far, most phenomenological studies from string compactification relied on \EE8 heterotic string, and this invites the SO(32) heterotic string very useful for future phenomenological studies. Here, spontaneous symmetry breaking is achieved by Higgsing of the anti-symmetric tensor representations of SU(N). The anti-SU(N) presented in this paper is a completely different class from the flipped-SU(N)s from the spinor representations of SO(2N). Here, we realize chiral representations: \tsix⊕5⋅\nineb for a SU(9) GUT and 3{\tenL′⊕\fivebL′} for a SU(5)′ GUT. In particular, we confirm that the non-Abelian anomalies of SU(9) gauge group vanish and hence our compactification scheme achieves the key requirement. We also present the Yukawa couplings, in particular for the heaviest fermion, t, and lightest fermions, neutrinos. In the supersymmetric version, we present a scenario how supersymmetry can be broken dynamically via the confining gauge group SU(9). Three families in the visible sector are interpreted as the chiral spectra of SU(5)′ GUT.
Recent discussions about supernova magnitude evolution have raised doubts about the robustness of the late-universe acceleration. In a previous letter, Huang did a null test of the cosmic acceleration by using a Parameterization based on the cosmic Age (PAge), which covers a broad class of cosmological models including the standard Λ cold dark matter model and its many extensions. In this work, we continue to explore the cosmic expansion history with the PAge approximation. Using baryon acoustic oscillations ({\it without} a CMB prior on the acoustic scale), gravitational strong lens time delay, and passively evolving early galaxies as cosmic chronometers, we obtain ≳4σ detections of cosmic acceleration for both flat and nonflat PAge universes. In the nonflat case, we find a ≳3σ tension between the spatial curvatures derived from baryon acoustic oscillations and strong lens time delay. Implications and possible systematics are discussed.
We present lattice QCD results for masses and magnetic polarizabilities of light and strange pseudoscalar mesons, chiral condensates, decay constants of neutral pion, and neutral kaon in the presence of background magnetic fields with eB ranging up to around 3.35 GeV2 (∼70Mπ2) in the vacuum. The computations were carried out in (2+1)-flavor QCD mostly on 323×96 lattices using the highly improved staggered quark action with Mπ≈ 220 MeV at zero temperature. We find that the masses of neutral pseudoscalar mesons monotonously decrease as the magnetic field strength grows and then saturate at a nonzero value, while there exists a nonmonotonous behavior of charged pion and kaon masses in the magnetic field. We observe a qB scaling of the up and down quark flavor components of neutral pion mass, neutral pion decay constant as well as the quark chiral condensates at 0.05 ≲eB≲ 3.35 GeV2. We show that the correction to the Gell-Mann-Oakes-Renner relation involving the neutral pion is less than 6% and the correction for the relation involving neutral kaon is less than 30% at eB≲ 3.35 GeV2. We also derive the Ward-Takahashi identities for QCD in the magnetic field in the continuum formulation including the relation between integrated neutral pseudoscalar meson correlators and chiral condensates.
This dissertation treats the problem of complete experiments for pseudoscalar meson photoproduction, in the context of a truncated partial-wave analysis (TPWA). The work contains algebraic and numerical considerations. The influence of measurement uncertainties is examined using bootstrap methods. The thesis was originally published online by the University of Bonn in the 1st quarter of 2019 (links are given in the comments).
We elaborate further on the compatibility of the "vacuumon potential" that characterises the inflationary phase of the Running Vacuum Model (RVM) with the Swampland criteria. The work is motivated by the fact that, as demonstrated recently by the authors [1-3], the RVM framework can be derived as an effective gravitational field theory stemming from underlying microscopic (critical) string theory models with gravitational anomalies, involving condensation of primordial gravitational waves. Although believed to be a classical scalar field description, not representing a fully fledged quantum field, nonetheless we show here that the vacuumon potential satisfies certain Swampland criteria for the relevant regime of parameters and field range. We link the criteria to the Gibbons-Hawking entropy that has been argued to characterise the RVM during the de Sitter phase. These results imply that the vacuumon may, after all, admit under certain conditions, a rôle as a quantum field during the inflationary (almost de Sitter) phase of the running vacuum. The conventional slow-roll interpretation of this field, however, fails just because it satisfies the Swampland criteria. The RVM effective theory derived from the low-energy effective action of string theory does, however, successfully describe inflation thanks to the ∼H4 terms induced by the gravitational anomalous condensates. In addition, the stringy version of the RVM involves the Kalb-Ramond (KR) axion field, which, in contrast to the vacuumon, does perfectly satisfy the slow-roll condition. We conclude that the vacuumon description is not fully equivalent to the stringy formulation of the RVM.
Systematic understanding for classes of inflationary models is investigated from the viewpoint of the local conformal symmetry and the slightly broken global symmetry in the framework of the metric-affine geometry. In the metric-affine geometry, which is a generalisation of the Riemannian one adopted in the ordinary General Relativity, the affine connection is an independent variable of the metric rather than given e.g. by the Levi-Civita connection as its function. Thanks to this independency, the metric-affine geometry can preserve the local conformal symmetry in each term of the Lagrangian contrary to the Riemannian geometry, and then the local conformal invariance can be compatible with much more kinds of global symmetries. As simple examples, we consider the two-scalar models with the broken SO(1,1) or O(2), leading to the well-known α-attractor or natural inflation, respectively. The inflaton can be understood as their pseudo Nambu-Goldstone boson.
Experimental results related to charged particle and π0 suppression obtained at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven for Au-Au (Cu-Cu) collisions and at the Large Hadron Collider (LHC) at CERN for Pb-Pb (Xe-Xe) collisions are compiled in terms of the usual nuclear modification factors, RAA and RCP, and of the newly introduced RAAN and RCPN as a function of ⟨Npart⟩ and ⟨dNch/dη⟩. The studies are focused on a pT range in the region of maximum suppression evidenced in the experiments. The core contribution to RAA is presented. Considerations on the missing suppression in high charged particle multiplicity events for pp collisions at 7 TeV are presented. The trends of RCP and RCPN for charged particles and RAAπ0 and (RAAN)π0 as a function of sNN, measured at RHIC in Au-Au collisions and at LHC in Pb-Pb collisions, show a suppression that becomes larger from sNN = 39 GeV up to sNN=200 GeV, followed by a saturation up to the highest energy of sNN =5.02 TeV in Pb-Pb collisions. A clear change in the dependence of (1−RAAπ0)/⟨dN/dy⟩ for the most central collisions as a function of collision energy is evidenced in the region of sNN =62.4 - 130 GeV.
TeV-scale particles that couple to the standard model through the weak force represent a compelling class of dark matter candidates. The search for such Weakly Interacting Massive Particles (WIMPs) has already spanned multiple decades, and whilst it has yet to provide any definitive evidence for their existence, viable parameter space remains. In this paper, we show that the upcoming Cherenkov Telescope Array (CTA) has significant sensitivity to uncharted parameter space at the TeV mass scale. To do so, we focus on two prototypical dark matter candidates, the Wino and Higgsino. Sensitivity forecasts for both models are performed including the irreducible background from misidentified cosmic rays, as well as a range of estimates for the Galactic emissions at TeV energies. For each candidate, we find substantial expected improvements over existing bounds from current imaging atmospheric Cherenkov telescopes. In detail, for the Wino we find a sensitivity improvement of roughly an order of magnitude in ⟨σv⟩, whereas for the Higgsino we demonstrate that CTA has the potential to become the first experiment that has sensitivity to the thermal candidate. Taken together, these enhanced sensitivities demonstrates the discovery potential for dark matter at CTA in the 1-100 TeV mass range.
Here we study two important properties of 2+1 dimensional QCD -- confinement and pseudoscalar glueball spectrum -- with holographic approach. We consider the low energy decoupled geometry of the isotropic non-susy D2 brane. We find the corresponding gauge theory is similar to the 2+1-dim Yang-Mills theory with the running coupling λ2. At the extremal limit (i.e. BPS limit), this gauge theory reduces to the super-YM theory. From the Nambu-Goto action of a test string, the potential of a \qq pair located on the boundary is calculated. At large \qq separation it gives the tension σ of the QCD flux-tube. The parametric dependencies of σ is shown pictorially. It is found that σ is a monotonically increasing function of the effective coupling λ2. In comparison, σ/gYM2Nc is found to match accurately with the previous results. In the next part, we consider fluctuation of the axion field in the aforementioned gravity background. From the linearized field equation of the fluctuation we calculate the mass spectrum of 0−+ numerically using the WKB approximation. The pseudoscalar mass is found to be related to the string tension approximately as M0−+/σ≈3(n+2) for first three energy states, n=0,1,2.
In this article, we review the status of the calculation of nuclear currents within chiral effective field theory. After formal discussion of the unitary transformation technique and its application to nuclear currents we will give all available expressions for vector, axial-vector currents. Vector and axial-vector currents will be discussed up to order Q with leading-order contribution starting at order Q−3. Pseudoscalar and scalar currents will be discussed up to order Q0 with leading-order contribution starting at order Q−4. This is a complete set of expressions in next-to-next-to-next-to-leading-order (N3LO) analysis for nuclear scalar, pseudoscalar, vector and axial-vector current operators. Differences between vector and axial-vector currents calculated via transfer-matrix inversion and unitary transformation techniques are discussed. The importance of consistent regularization is an additional point which is emphasized: lack of consistent regularization of axial-vector current operators is shown to lead to a violation of the chiral symmetry in the chiral limit at order Q. For this reason, a hybrid approach at order Q, discussed in various publications, is non-applicable. To respect the chiral symmetry the same regularization procedure needs to be used in the construction of nuclear forces and current operators. Although full expressions of consistently regularized current operators are not yet available an isoscalar part of the electromagnetic charge operator up to order Q has a very simple form and can be easily regularized in a consistent way. As an application, we review our recent high accuracy calculation of the deuteron charge form factor with a quantified error estimate.
We consider the sets of Dirac-Maxwell and Rarita-Schwinger-Maxwell equations in R×S3 spacetime. Using the Hopf coordinates, we show that these equations allow separation of variables and obtain the corresponding analytic and numerical solutions. It is also demonstrated that the current of the Dirac field is related to the Hopf invariant on the S3→S2 fibration.
We derive new constraints on models of decaying and annihilating dark matter (DM) by requiring that the energy injected into the intergalactic medium (IGM) not overheat it at late times, when measurements of the Lyman-α forest constrain the IGM temperature. We improve upon previous analyses by using the recently developed DarkHistory code package, which self-consistently takes into account additional photoionization and photoheating processes due to reionization and DM sources. Our constraints are robust to the uncertainties of reionization and competitive with leading limits on sub-GeV DM that decays preferentially to electrons.
↳ astro-ph.COhep-phPRD(2021)·72 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.