In this work we consider anomalous and linear holographic hard wall (HW) models for light unflavored mesons inspired by the AdS/CFT correspondence. The anomalous dimensions depend on the logarithm of the spin S of the meson state and come from a semiclassical analysis of gauge/string duality. The anomalous HW model produces very good masses and good Regge trajectories for mesons compared with PDG data. Inspired by this anomalous HW model we also propose a phenomenological modification of the dimension of the boundary operators such that the model produces asymptotic linear Regge trajectories. Both anomalous HW models considered here present mass percentage deviations of less than 3%, when compared with PDG data.
We consider all magnetic monopoles that could have settled in the Standard Model after descending from a generic microscopic theory. These monopoles have Standard Model quantum numbers, are stable, and we also require that their magnetic fluxes are consistent with the electroweak symmetry breaking. Scattering processes involving quarks, leptons and protons on these monopoles are studied using partial waves decomposition. These processes in the lowest partial wave are known to be unsuppressed by the monopole mass and are relevant for monopole catalysis of proton decay. We provide estimates for scattering cross-sections and investigate and confirm the applicability of the twisted sector approach to scattering processes on these Standard Model monopoles. We find that the SM monopole catalysis processes are universal and model-independent.
The relationship between QCD and the string model offers a valuable perspective for exploring the interaction potential between quarks. In this study, we investigate the restoration of chiral symmetry in connection with the Unruh effect experienced by accelerating observers. Utilizing the Schwinger model, we analyze the critical point at which the string or chromoelectric flux tube between quark-antiquarks breaks with increasing separation between quarks. In this study, the critical distance for quark-antiquark chromoelectric flux tube or string breaking is determined to be rc=1.294±0.040 fm. The acceleration and Unruh temperature corresponding to this critical point signify the transition of the system's chiral symmetry from a broken to a restored state. Our estimates for the critical acceleration (ac=1.14×1034 cm/s2) and Unruh temperature (Tc=0.038 GeV) align with previous studies. This analysis illuminates the interplay between chiral symmetry restoration, the Unruh effect, and the breaking of the string or chromoelectric flux tube within the context of quark interactions.
The commonly used pseudo-C symmetry (νL)c=CνLT is not defined in Lagrangian field theory. In general, there exist two classes of Majorana fermions; the first is associated with the Dirac-type fermion with the conventional C and P symmetries, and the second is associated with the Weyl-type fermion defined by CP symmetry only and formally characterised by the pseudo-C symmetry. Taking the seesaw model as an example, it is shown that a generalized Pauli--Gürsey (or Bogoliubov-type) canonical transformation converts the neutrino defined by the Weyl-type fermion to the neutrino defined by the Dirac-type fermion and thus to the conventional Majorana fermion, while preserving the canonical anti-commutation relations. The mixing angles in the weak lepton sector are not modified by this generalized Pauli--Gürsey transformation.
We study the realization of spontaneous CP violation through moduli stabilization. In modular flavor models, the source of CP violation is the vacuum expectation values of the complex structure moduli of toroidal compact space. We demonstrate that the combined effects of Type IIB flux compactifications with modular invariant couplings between the moduli and matter fields can induce spontaneous CP violation without or with supersymmetry breaking. Furthermore, some general properties of CP and modular invariant scalar potentials are presented. It is found that certain modifications or partial breakings of modular symmetry are useful in generating spontaneous CP violation.
The Standard Model (SM) Higgs boson, the most recently discovered elementary particle, may still serve as a mediator between the SM sector and a new physics sector related to dark matter (DM). The Large Hadron Collider (LHC) has not yet fully constrained the physics associated with the Higgs boson, leaving room for such possibilities. Among the various potential mass scales of the dark sector, the sub-GeV mass range is particularly intriguing. This parameter space presents significant challenges for DM direct detection experiments that rely on nuclear recoils. Various innovative experimental methods are currently under investigation to explore this sub-GeV dark sector. The LHC, functioning as a Higgs factory, could explore this sector once the challenge of identifying DM signals is resolved. Due to the significantly lower mass of particles in the dark sector compared to the Higgs boson, these particles are expected to be highly boosted following the Higgs boson's decay. However, detecting and identifying these highly boosted particles remains a considerable challenge at the LHC, despite their eventual decay into SM particles. We employ a well-motivated leptophobic ZB′ model as a prototype to analyze the distinctive signatures from Higgs boson exotic decays into multi-photons. These signatures consist of collimated photons that fail to meet the photon isolation criteria, forming jet-like objects. Conventional analyses relying solely on the purity of energy deposits in the electromagnetic calorimeter would fail to detect these signatures, as they would be overwhelmed by background events from Quantum Chromodynamics. To effectively distinguish between such novel signal signatures and SM background events, we leverage advanced machine learning techniques, specifically the transformer encoder in a multimodal network structure.
We present the analytic total cross section of top quark pair production in electron-positron annihilation at next-to-next-to-leading order (NNLO) in Quantum Chromodynamics (QCD). By utilizing the optical theorem, the NNLO corrections are related to the imaginary parts of three-loop self-energy Feynman diagrams, of which the master integrals are calculated with canonical differential equations. The analytic results for the NNLO corrections are expressed in terms of multiple polylogarithms as well as elliptic functions. We discuss the asymptotic expansions near the threshold and in the high energy limit in detail. Numerical results are provided for the total cross section of top quark pair production at future lepton colliders.
While searching at the Large Hadron Collider (LHC) for the production and decay of the CP-odd scalar (A0) in the 2-Higgs-Doublet Model (2HDM) with Natural Flavour Conservation (NFC) via the channels gg→A0 (through one-loop triangle diagrams) and A0→h0Z∗ (with mh0=125 GeV or mh0<125 GeV, with Z off-shell), respectively, a factorisation of the two processes is normally performed, with the A0 state being on-shell. While this approach is gauge-invariant, it is not capturing the presence of either of the following two channels: gg→Z∗→h0Z∗ (through one-loop triangle diagrams) or gg→h0Z∗ (through one-loop box diagrams). As the resolution of the A0 mass cannot be infinitely precise, we affirm that all such contributions should be computed simultaneously, whichever the h0(Z∗) decay(splitting) products, thereby including all possible interferences amongst themselves. The cross section of the ensuing complete process is significantly different from that obtained in the factorisation case, being of the order up to ten percent in either direction at the integrated level and larger (including changes in the shape of kinematical observables) at the differential level. We thus suggest that the complete calculation ought to be performed while searching for A0 in this channel. We illustrate this need for the case of a 2HDM of Type-I in the inverted hierarchy scenario with mh0<125 GeV.
Following the work of Capstick and Isgur [\href{https://doi.org/10.1103/PhysRevD.34.2809}{Phys.~Rev.~D~34,~2809~(1986)}], we systematically study the mass spectrum of the heavy baryons in the relativized quark potential model with chromodynamics. Besides the original Godfrey-Isgur (GI) model, we also adopt a modified GI model which replaces the linear confinement by a screened one. The two models give similar results in our work. All heavy baryons observed so far can be explained as three-quark states. In particular, we identify the Ωc(3000)/Ωb(6316), Ωc(3050)/Ωb(6330), Ωc(3065)/Ωb(6340) and Ωc(3090)/Ωb(6350) states as the pλ excitations with quantum numbers 1/2−, 3/2−, 3/2− and 5/2−. The Ωc(3120) is a 3/2− state with the pρ excitation, whose bottom partner is predicted to be Ωb(6446/6457,3/2−). The higher state Ωc(3188) is the 2sλ excitation with quantum numbers 1/2+, and Ωc(3327) is a dλ excitation with quantum numbers 3/2+ or 5/2+. In addition, the Λc(2940) with quantum numbers JP=3/2− could be explained as the pρ excitation.
This study explores fully leptonic WZ and WW production at the LHC within the SMEFT framework at NLO in QCD, focusing on both CP-even and CP-odd triple-gauge-coupling dimension-six operators. We investigate the off-shell processes, contrasting our findings in inclusive setups with those in the presence of realistic fiducial selections. Alongside the conventional kinematic observables, we examine polarisation-sensitive observables and angular coefficients. Moreover, we assess potential SMEFT effects on asymmetry observables. Through a sensitivity analysis, we identify critical LHC observables that are particularly sensitive to SMEFT-induced modifications, thereby shedding light on potential avenues for new-physics searches in diboson production at the LHC.
Dark sector may exist and interact with Standard Model (SM) through the U(1) kinetic mixing. Through this portal-type interaction, dark photon from dark sector couples to SM fermions, and may explain the discrepancy between experimental data and SM calculations on muon anomalous magnetic moment, muon g−2. However, current searches for dark photon impose stringent constraints on the mixing parameter ε for various dark photon masses, excluding the favorite parameter space for muon g−2. In this paper, we study the case where a global U(1) in dark sector is spontaneously broken, resulting a light pseudo-Goldstone, axion-like particle (ALP) a, which couples to dark photon and SM photon, gaγγ′. Through this interaction, dark photon may decay into photon and ALP when this channel is kinematically allowed. As a result, the experimental constraints on dark photon change significantly, and dark photon is able to explain the muon g−2 anomaly when its mass is heavier than 10 GeV.
In this study, we investigate the transverse momentum spectra of K±, π± and p(pˉ) in mid-rapidity (∣y∣<0.1) for nine centrality classes ranging from 0% to 80% in 238U+238U collisions at sNN=193 GeV. The simulations are performed using the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, specifically employing both the cascade mode and the soft momentum-dependent equation of state (SM-EoS) mode. Additionally, we extract other observables from the pT spectrum, including the average transverse momentum (⟨pT⟩), the particle yield (dN/dy) and particle-type ratios, presenting them as a function of collision centrality. We find that the collision dynamics are significantly sensitive to the prolate deformation of the uranium nuclei, which influences the initial geometry and subsequent particle production. We find that the U+U collision dynamics are highly sensitive to the deformation of the uranium nucleus. Consequently, the cascade mode is more appropriate for describing the low-pT region (pT<1.2GeV/c), while the SM-EoS mode better captures the trends in the high-pT region (pT>1.2GeV/c). Furthermore, at RHIC energies, our results indicate that pair production is the dominant mechanism for particle creation in the mid-rapidity region. This conclusion is corroborated by the particle-to-antiparticle production ratio, which approaches unity-indicating a high degree of matter-antimatter symmetry in the observed collision events.
The formation of hadrons is a fundamental process in nature that can be investigated at particle colliders. As several recent findings demonstrate, with e+e− collisions as a "vacuum-like" reference at one extreme, and central nucleus--nucleus as a dense, extended-size system characterized by flow and local equilibrium at the opposite extreme, different collision systems offer a lever arm that can be exploited to probe with a range of heavy-flavour hadron species the onset of various hadronization processes. In this review, we present an overview of the theoretical and experimental developments. The focus is on open-heavy-flavour measurements. The comparison with model predictions and connections among the results in electron-positron, proton--proton, proton--nucleus, nucleus--nucleus collisions are discussed. After reviewing the current state, we suggest some prospects and future developments.
We develop an effective and methodical algorithm for the construction of general covariant four-point HℓℓZ vertices, accommodating leptons ℓ=e,μ, and designed to handle a boson H of any integer spin, not merely confined to spins up to 2. While our numerical analysis assumes the H-boson mass to be mH=125GeV, the analytical framework we propose is versatile, enabling the examination of various mass as well as spin scenarios. These meticulously devised general covariant four-point HℓℓZ vertices are pivotal in vetoing all the imposters of the Standard Model Higgs boson holding the spin-0 and even-parity quantum numbers, especially in one of its primary decay channels, the three-body decay process H→ℓ−ℓ+Z, observable at the Large Hadron Collider. Our innovative strategy encompasses the analysis of all the effectively allowed scenarios, extending beyond the limitations of previous investigations on the Higgs spin and parity determinations in the decay H→ℓ−ℓ+Z. Based on the significantly expanded scheme, we demonstrate that the Higgs boson imposter of any spin and parity can be definitively vetoed by leveraging threshold effects and angular correlations, even though achieving such conclusive results in practical and exhaustive analyses necessitates high event rates.
This study explores the transverse momentum (pT) dependencies of Symmetric and Asymmetric Correlations (SC and ASC) with one and two particles of interest in Au+Au collisions at 200 GeV. Leveraging the AMPT model, the investigation delves into the sensitivity of these correlations to the final state effects, providing valuable insights into their potential for constraining the final state effects' pT dependencies. The HIJING model is employed as a benchmark for non-flow correlations, shedding light on their impact on interpreting SC and ASC data. Moreover, the study points out that differential SC and ASC with one and two particles of interest (POIs) typically incorporate contributions from event-plane angle fluctuations. Consequently, this work highlights the significance of SC and ASC with one and two POIs as valuable tools for investigating the pT nature of the final state effects and advocates for comprehensive experimental measurements across various beam energies and system sizes to enhance our understanding and provide additional constraints for theoretical models.
We study the discovery prospects for a charged Higgs boson via the bg→cH−→ctˉb process at the Large Hadron Collider (LHC). Focusing on the general Two Higgs Doublet Model (G2HDM) that possesses extra Yukawa couplings, the process is controlled by extra top couplings ρtc and ρtt, which can drive electroweak baryogenesis (EWBG) to account for the baryon asymmetry of the Universe (BAU). We propose benchmark points (BPs) and demonstrate that evidence could emerge at 14 TeV LHC and luminosity of 300 fb−1, with discovery potential at 600 fb−1.
Recent experimental data from pp collisions have shown a significant increase in heavy baryon production leading to a baryon over meson ratio which is one order of magnitude higher than elementary collisions (e+e−, ep). From a theoretical point of view this large production of baryon can be explained with hadronization via quark coalescence assuming a QGP medium in pp collisions. In this study, we extend this analysis to include hadrons containing bottom quarks. Employing a coalescence plus fragmentation approach, we present predictions for pT spectra and the heavy baryon/meson ratio of charmed hadrons with and without strangeness content, specifically: B0ˉ, Bs, Λb, Ξb0,−, Ωb, and the Bc meson. We have found that coalescence is the dominant mechanism in the B meson production, especially at low momenta, at variance with what found in the charm sector where the D meson were mainly produced via fragmentation. Our model predicts a Λb/B0ˉ≈0.5−1 and Ξb0/B0ˉ ratio around 0.3 at very low transverse momentum, which are about 1.5 larger then those of the corresponding charmed hadron ratios at the same collision energy. Furthermore, we discuss the relative ratios between charmed and bottomed hadrons, emphasizing how these observables can provide information about the distribution of charm and bottom quarks and, if experimentally observed, would further support the idea of quark-gluon plasma formation even in small collision systems.
We show that if dark matter consists of QCD axions in the post-inflationary scenario more than ten percent of it efficiently collapses into Bose stars at matter-radiation equality. Such a result is mostly independent of the present uncertainties on the axion mass. This large population of solitons, with asteroid masses and Earth-Moon distance sizes, might plausibly survive until today, with potentially interesting implications for phenomenology and experimental searches.
It has long been established that axions could have been produced within the nascent proto-neutron-star formed following the type II supernova SN1987A, escaped the star due to their weak interactions, and then converted to gamma-rays in the Galactic magnetic fields; the non-observation of a gamma-ray flash coincident with the neutrino burst leads to strong constraints on the axion-photon coupling for axion masses ma≲10−10 eV. In this work we use SN1987A to constrain higher mass axions, all the way to ma∼10−3 eV, by accounting for axion production from the Primakoff process, nucleon bremsstrahlung, and pion conversion along with axion-photon conversion on the still-intact magnetic fields of the progenitor star. Moreover, we show that gamma-ray observations of the next Galactic supernova, leveraging the magnetic fields of the progenitor star, could detect quantum chromodynamics axions for masses above roughly 50 μeV, depending on the supernova. We propose a new full-sky gamma-ray satellite constellation that we call the GALactic AXion Instrument for Supernova (GALAXIS) to search for such future signals along with related signals from extragalactic neutron star mergers.
Energy correlators provide a powerful observable to study fragmentation dynamics in QCD. We demonstrate that the leading nonperturbative corrections for projected N-point energy correlators are described by the same universal parameter for any N, which has already been determined from other event shape fits. Including renormalon-free nonperturbative corrections substantially improves theoretical predictions of energy correlators, notably the transition into the confining region at small angles. Nonperturbative corrections are shown to have a significant impact on αs extractions.
Motivated by the ion-collision program at the Large Hadron Collider, plans for its high-luminosity upgrade, and on-going discussions for multi-TeV future hadron colliders, we systematically investigate hard-scattering, Standard Model processes in many-TeV ion-ion collisions. We focus on the symmetric beam configurations 208Pb-208Pb, 131Xe-131Xe, 12C-12C, and pp, and we catalog total and fiducial cross sections for dozens of processes, ranging from associated-Higgs and multiboson production to associated-top pair production, at next-to-leading order in QCD for nucleon-nucleon collision energies from sNN=1 to 100 TeV. We report the residual scale uncertainties at this order as well as the uncertainties originating from fits of nuclear parton densities. We also discuss the propagation of nuclear dynamics (as encoded in nuclear parton densities) into parton luminosities, and ultimately into predictions for cross sections. Finally, we report on the emergence of trends and the reliability of extrapolating cross sections across different nuclei. For Pb-Pb collisions at a hypothetical Future Circular Collider with sNN=39 TeV, O(108) weak bosons, O(105) diboson pairs, O(104)WH and ZH pairs, O(103) triboson events, O(105) high-pT photons events, and O(107)tt pairs can be produced with L=33~nb−1 of data. At sNN=5.52 TeV, one can expect O(10−106) single, multiboson, and top events per 1 nb−1. Decay rates and experimental selection/acceptance rates will impact final event yields, and merits further study; as an illustrative example, we focus on select diboson and triboson channels in lead-lead collisions and discuss their observability at the high-luminosity phase of the LHC and the FCC.
We compute inclusive dihadron cross-section in Deep Inelastic Scattering at next-to-leading order (NLO) and small x in the Color Glass Condensate. We focus on the kinematic limit where the hadrons are produced at forward rapidities (in the direction of the virtual photon) and back-to-back in the transverse plane. Our calculation demonstrates that the coefficient of the Sudakov double logarithm for this process is −2παs[CF+2Nc] instead of −4παsNc when back-to-back jets are measured in the final state. To preserve the universality of the Sudakov soft factor associated with the Weizsäcker-Williams transverse momentum dependent (TMD) gluon distribution, we promote the collinear fragmentation functions into TMD fragmentation functions. We then perform the resummation of the Sudakov logarithms through Collins-Soper-Sterman evolution of the TMD fragmentation functions and the Weizsäcker-Williams TMD gluon distribution. Finally, analytic expressions are obtained for the NLO coefficient functions in the MS-scheme. These results pave the way towards numerically calculating dihadron correlations at small x at the future Electron-Ion Collider with full NLO accuracy.
Gravitational wave observations of black hole-neutron star binaries, particularly those where the black hole has a lower mass compared to other observed systems, have the potential to place strong constraints on modifications to general relativity that arise at small curvature length scales. Here we study the dynamics of black hole-neutron star mergers in shift-symmetric Einstein-scalar-Gauss-Bonnet gravity, a representative example of such a theory, by numerically evolving the full equations of motion. We consider quasi-circular binaries with different mass-ratios that are consistent with recent gravitational wave observations, including cases with and without tidal disruption of the star, and quantify the impact of varying the coupling controlling deviations from general relativity on the gravitational wave signal and scalar radiation. We find that the main effect on the late inspiral is the accelerated frequency evolution compared to general relativity, and that--even considering Gauss-Bonnet coupling values approaching those where the theory breaks down--the impact on the merger gravitational wave signal is mild, predominately manifesting as a small change in the amplitude of the ringdown. We compare our results to current post-Newtonian calculations and find consistency throughout the inspiral.
This is a short account, based on a talk given at the 2024 Moriond Cosmology Conference, of where and why string theory matters in early universe cosmology. It is written for a cosmology audience predisposed to be at best sceptical, and at worst contemptuous, of the notion that either quantum gravity or string theory has any relevance for their discipline. I cover inflation, CMB tensor modes, extended kination or tracker epochs and reheating.
Spatial structuring of materials at subwavelength scales underlies the concept of metamaterials possessing exotic properties beyond those of the constituent media. Temporal modulation of material parameters enables further functionalities. Here, we show that high-frequency oscillations of spatially uniform magnetization generate an effective dynamic axion field embedding the amplitude and phase of magnetization oscillations. This allows one to map ultrafast magnetization dynamics using a probe signal with much lower frequency.
We present preliminary results of a partial-wave analysis of τ−→π−π−π+ντ using data from the Belle experiment at the KEKB e+e− collider. We validate our model with a model-independent analysis. We see the a1(1420) and a G-parity-violating 1−[ω(782)π]P wave in tauon decays. Our results will improve models used in simulation studies necessary for measuring the electric and magnetic dipole moments and Michel parameters of the τ.
We report the first \textit{ab initio} calculation of the nuclear-structure-dependent radiative correction δNS to the 10C→10B superallowed transition, computed with the no-core shell model and chiral effective field theory. We obtain δNS=−0.422(29)nuc(12)n,el with a 1.6-times reduction in the total uncertainty when compared to the current literature estimate based on the shell model and Fermi gas picture. This work paves the way for a precise determination of Vud from superallowed beta decays within a systematically improvable framework.
Dark photons are a theorized massive spin-1 particle which can be produced via various mechanisms, including cosmological gravitational particle production (GPP) in the early universe. In this work, we extend previous results for GPP of dark photons to include nonminimal couplings to gravity. We find that nonminimal couplings can induce a ghost instability or lead to runaway particle production at high momentum and discuss the constraints on the parameter space such that the theory is free of instabilities. Within the instability-free regime we numerically calculate the particle production and find that the inclusion of nonminimal couplings can lead to an enhancement of the particle number. As a result, GPP of nonminimally coupled dark photons can open the parameter space for production of a cosmological relevant relic density (constituting all or part of the dark matter) as compared to the minimally-coupled theory. These results are independent of the choice of inflation model, which we demonstrate by repeating the analysis for a class of rapid-turn multi-field inflation models.
Context. Merging compact objects such as binary black holes provide a promising probe for the physics of dark matter (DM). The gravitational waves emitted during inspiral potentially allow one to detect DM spikes around black holes. This is because the dynamical friction force experienced by the inspiralling black hole alters the orbital period and thus the gravitational wave signal. Aims. The dynamical friction arising from DM can potentially differ from the collisionless case when DM is subject to self-interactions. This paper aims to understand how self-interactions impact dynamical friction. Methods. To study the dynamical friction force, we use idealised N-body simulations, where we include self-interacting dark matter. Results. We find that the dynamical friction force for inspiralling black holes would be typically enhanced by DM self-interactions compared to a collisionless medium (ignoring differences in the DM density). At lower velocities below the sound speed, we find that the dynamical friction force can be reduced by the presence of self-interactions. Conclusions. DM self-interactions have a significant effect on the dynamical friction for black hole mergers. Assuming the Chandrasekhar formula may underpredict the deceleration due to dynamical friction.
Many machine learning models based on neural networks exhibit scaling laws: their performance scales as power laws with respect to the sizes of the model and training data set. We use large-N field theory methods to solve a model recently proposed by Maloney, Roberts and Sully which provides a simplified setting to study neural scaling laws. Our solution extends the result in this latter paper to general nonzero values of the ridge parameter, which are essential to regularize the behavior of the model. In addition to obtaining new and more precise scaling laws, we also uncover a duality transformation at the diagrams level which explains the symmetry between model and training data set sizes. The same duality underlies recent efforts to design neural networks to simulate quantum field theories.
* 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.