Wed·Oct 23, 2019Wednesday·October 23, 2019

1. 01*

   Inverse see-saw neutrino masses in the Littlest Higgs model with T-parity

   Francisco del Aguila🇪🇸 · José Ignacio Illana🇪🇸 · José María Perez-Poyatos🇪🇸 · José Santiago🇪🇸

   We show that the inverse see-saw is the most natural way of implementing neutrino masses in the Littlest Higgs model with T-parity. The three extra quasi-Dirac neutrinos are needed to cancel the quadratically divergent contributions of the mirror leptons to the Higgs mass. If the T-parity of the heavy neutrino singlets is chosen to be even, their contributions to lepton flavor violating transitions are one-loop finite. The most stringent limits on this scenario result from the non-observation of these transitions. Constraints on neutrino mixing imply an upper bound on the mass of the T-odd mirror leptons at the reach of the LHC and/or future colliders.

   hep-phJHEP(2019)·19 citations
2. 02*

   Four-top as probe of light top-philic New Physics

   Ezequiel Alvarez🇦🇷 · Aurelio Juste🇪🇸 · Rosa María Sandá Seoane🇦🇷

   We study the four-top final state at the LHC as a probe for New Physics (NP) effects due to new particles that couple predominantly to the top quark and whose masses are below the top-quark-pair production threshold. We consider simple NP models containing a new particle with either spin 0, spin 1, or spin 2, and find benchmark points compatible with current experimental results. We find that interference effects between NP and QED amplitudes can be large, pointing out the necessity of NLO contributions to be explicitly computed and taken into account when NP is present. We examine kinematic differences between these models and the Standard Model (SM) at the parton level and the reconstructed level. In the latter case, we focus on events selected requiring two same-sign leptons and multiple jets. We investigate how the different Lorentz structure of the light NP affects the kinematic hardness, the polarization, the spin correlations, and the angular distributions of the parton-level and/or final-state particles. We find that spin-2 light NP would be identified by harder kinematics than the SM. We also show that the angular separation between the same-sign leptons is a sensitive observable for spin-0 NP. The spin-0 and spin-2 NP cases would also yield a signal in $t\bar{t}\gamma \gamma$ with the invariant mass of the photons indicating the mass of the new particle. The spin-1 NP would be identified through an excess in four-top signal and slight or not modification in other observables, as for instance the lack of signal in $t\bar{t}\gamma \gamma$ due to the Landau-Yang theorem. We comment on the opportunities that would open from the kinematic reconstruction of some of the top quarks in the four-top state. Our results provide new handles to probe for light top-philic NP as part of the ongoing experimental program of searches for four-top production at the LHC Run 2 and beyond.

   hep-phhep-exJHEP(2019)·20 citations
3. 03*

   Single-spin asymmetries in $p^{\uparrow }p\to J/\psi +X$ within a TMD approach: role of the color octet mechanism

   Umberto D'Alesio🇮🇹 · Francesco Murgia🇮🇹 · Cristian Pisano🇮🇹 · Sangem Rajesh🇮🇹

   We calculate the transverse single-spin asymmetry (SSA) for $J/\psi$ production in proton-proton collisions, within non-relativistic QCD, employing the transverse momentum dependent, generalized parton model, which includes both spin and intrinsic motion effects. In particular, we study the role of the color octet mechanism in accessing the gluon Sivers function. In doing that, we also show, within this approach, how the singularities coming from color octet terms in the low-$P_T$ region can be handled, leading to finite cross sections. Predictions for both unpolarized cross sections and SSAs are given and compared against PHENIX data. Estimates for LHCb in the fixed target mode are also presented.

   hep-phEPJC(2019)·24 citations
4. 04*

   Patterns and partners within the QCD phase diagram including strangeness

   Angel Gómez Nicola🇪🇸 · Jacobo Ruiz de Elvira🇨🇭 · Andrea Vioque-Rodríguez🇪🇸

   We review the current situation of the pattern of chiral symmetry restoration. In particular, we analyze partner degeneration for $O(4)$ and $U(1{)}_A$ symmetries within the context of Ward Identities and Effective Theories. The application of Ward Identities to the thermal scaling of screening masses is also discussed. We present relevant observables for which an Effective Theory description in terms of Chiral Perturbation Theory and its unitarized extension are compatible with lattice data even around the transition region. We pay special attention to the role of strangeness in this context.

   hep-phSpringer Proc.Phys.(2020)·1 citation
5. 05*

   Pathologies of the KMR prescriptions for unintegrated PDFs: Which prescription should be preferred?

   Benjamin Guiot🇨🇱

   We discuss the different Kimber-Martin-Ryskin (KMR) prescriptions for unintegrated parton distribution functions (uPDFs). We show that the strong-ordering (SO) and the angular-ordering (AO) cut-offs lead to strong discrepancies between the obtained cross sections. While the result obtained with the AO cut-off overestimates the heavy-flavor cross section by about a factor 3, the SO cut-off gives the correct answer. We also solve the issue of the KMR uPDFs definitions mentioned by Golec-Biernat and Staśto, and show that, in the case of the AO cut-off, the KMR uPDFs are ill-defined.

   hep-phPRD(2020)·26 citations
6. 06*

   Hunting Inflaton at FASER

   Nobuchika Okada🇺🇸 · Digesh Raut🇺🇸

   We explore a possibility that an inflaton, which drives the cosmological inflation in the early Universe, can be detected by the recently approved FASER at the High-Luminosity LHC (HL-LHC). We consider nonminimal quartic inflation scenario in the minimal U(1)${}_X$ extension of the Standard Model (SM) with the classical conformal invariance, where the inflaton is identified with the U(1)${}_X$ Higgs field ($\varphi$). By virtue of the classical conformal invariance and the radiative U(1)${}_X$ symmetry breaking via the Coleman-Weinberg mechanism, the inflationary predictions (in particular, the tensor-to-scaler ratio ($r$)), the U(1)${}_X$ coupling ($g_X$) and the U(1)${}_X$ gauge boson mass ($m_{Z^{\prime }}$), are all determined by only two free parameters, the inflaton mass ($m_{\varphi }$) and its mixing angle ($\theta$) with the SM Higgs field. The FASER can search for the inflaton for the parameter ranges of $0.1\lesssim m_{\varphi }[\mathrm{GeV}]\lesssim 4$ and $10^{-5}\lesssim \theta \lesssim 10^{-3}$. Because of the direct connection among $r$, $g_X$ and $m_{Z^{\prime }}$, the $Z^{\prime }$ boson resonance search at the HL-LHC and the future measurement of the primordial gravitational wave are complementary to the inflaton search at the FASER.

   hep-phPRD(2021)·26 citations
7. 07*

   Heavy quarkonium in saturated environment of high-multiplicity pp collisions

   B. Z. Kopeliovich🇨🇱 · H. J. Pirner🇩🇪 · I. K. Potashnikova🇨🇱 · K. Reygers🇩🇪 · Ivan Schmidt🇨🇱

   High-multiplicity pp collisions exhibit features, traditionally associated with nuclear effects. Coherence motivates to treat high-multiplicity pp, pA and AA collisions on an equal footing. We rely on the phenomenological parametrization for mean multiplicities of light hadrons and J/psi, assuming their linear dependence on N_{coll} in pA collisions. The results of this approach underestimate the recently measured production rate of J/psi at very high hadronic multiplicities. The linear dependence of J/psi multiplicity on N_{coll} is subject to predicted nonlinear corrections, related to mutual boosting of the saturation scales in colliding dense parton clouds. A parameter-free calculation of the non-linear corrections allows to explain data for pT-integrated yield of J/psi at high hadronic multiplicities. Calculations are in a good accord with data binned in several pT-intervals as well. As was predicted, Upsilon and J/psi are equally suppressed at forward rapidities in pA collisions. Consequently, their fractional multiplicities at forward rapidities in pp collisions are equal as well, and their magnitude agrees with data.

   hep-phPRD(2020)·18 citations
8. 08*

   Maximum value of the spin-independent cross section in the THDM+a

   Tomohiro Abe🇯🇵 · Motoko Fujiwara🇯🇵 · Junji Hisano🇯🇵 · Yutaro Shoji🇯🇵

   We investigate the maximum value of the spin-independent cross section (${\sigma }_{\text{SI}}$) in a dark matter (DM) model called the two-Higgs doublet model + a (THDM+a). This model can explain the measured value of the DM energy density by the freeze-out mechanism. Also, ${\sigma }_{\text{SI}}$ is suppressed by the momentum transfer at the tree level, and loop diagrams give the leading contribution to it. The model prediction of ${\sigma }_{\text{SI}}$ highly depends on values of $c_1$ and $c_2$ that are the quartic couplings between the gauge singlet CP-odd state ($a_0$) and Higgs doublet fields ($H_1$ and $H_2$), $c_1{a}_0^2{H}_1^{†}{H}_1$ and $c_2{a}_0^2{H}_2^{†}{H}_2$. We discuss the upper and lower bounds on $c_1$ and $c_2$ by studying the stability of the electroweak vacuum, the condition for the potential bounded from the below, and the perturbative unitarity. We find that the condition for the stability of the electroweak vacuum gives upper bounds on $c_1$ and $c_2$. The condition for the potential to be bounded from below gives lower bounds on $c_1$ and $c_2$. It also constrains the mixing angle between the two CP-odd states. The perturbative unitarity bound gives the upper bound on the Yukawa coupling between the dark matter and $a_0$ and the quartic coupling of $a_0$. Under these theoretical constraints, we find that the maximum value of the ${\sigma }_{\text{SI}}$ is $\sim 5\times 10^{-47}$ cm${}^2$ for $m_A=$ 600 GeV, and the LZ and XENONnT experiments can see the DM signal predicted in this model near future.

   hep-phJHEP(2020)·26 citations
9. 09*

   New physics with boosted single top production at the LHC and future colliders

   J.A. Aguilar-Saavedra🇪🇸 · M.L. Mangano🇨🇭

   We address the potential of measurements with boosted single-top final states at the high-luminosity LHC (HL-LHC) and possible future hadron colliders: the high-energy LHC (HE-LHC), and the future circular collider (FCC). As new physics examples to assess the potential, we consider the search for $tbW$ anomalous couplings and for a weakly-coupled $W^{\prime }$ boson. The FCC would improve by a factor of two the sensitivity to anomalous couplings of the HL-LHC. For $W^{\prime }$ bosons, the FCC is sensitive to $W^{\prime }$ couplings $2-5$ times smaller than the HL-LHC in the mass range 2-4 TeV, and to masses up to 30 TeV in the case of Standard Model-like couplings.

   hep-phhep-exEPJC(2020)·15 citations
10. 10*

    Probing Virtual Axion-Like Particles by Precision Phase Measurements

    Moslem Zarei🇮🇷 · Soroush Shakeri🇮🇷 · Mohammad Sharifian🇮🇷 · Mehdi Abdi🇮🇷 · David J. E. Marsh🇩🇪 · Sabino Matarrese🇮🇹

    We propose an experiment for detecting Axion-Like Particles (ALPs) based on the axion-photon interaction in the presence of a non-uniform magnetic field. The impact of virtual ALPs on the polarization of the photons inside a cavity is studied and a detection scheme is proposed. We find that the cavity normal modes are dispersed differently owing to their coupling to the ALPs in the presence of a background magnetic field. This birefringence, in turn, can be observed as a phase difference between the cavity polarization modes. The signal is considerably enhanced for a squeezed light source. We argue that the amplified signal allows for exclusion of a range of axion mass $6\times 10^{-4}\text{eV}\lesssim m_a\lesssim 6\times 10^{-3}\text{eV}$ even at very small axion-photon coupling constant with the potential to reach sensitivity to the QCD axion. Our scheme allows for the exclusion of a range of axion masses that has not yet been covered by other experimental techniques.

    hep-phastro-ph.COhep-exquant-phJCAP(2022)·25 citations
11. 11*

    Two-particle contributions and nonlocal effects in the QCD sum rules for the axialvector tetraquark candidate $Z_c(3900)$

    Zhi-Gang Wang🇨🇳

    In this article, we study the $Z_c(3900)$ with the QCD sum rules in details by including the two-particle scattering state contributions and nonlocal effects between the diquark and antidiquark constituents. The two-particle scattering state contributions cannot saturate the QCD sum rules at the hadron side, the contribution of the $Z_c(3900)$ plays an un-substitutable role, we can saturate the QCD sum rules with or without the two-particle scattering state contributions. If there exists a barrier or spatial separation between the diquark and antidiquark constituents, the Feynman diagrams can be divided into the factorizable and nonfactorizable diagrams. The factorizable diagrams consist of two colored clusters and lead to a stable tetraquark state. The nonfactorizable Feynman diagrams correspond to the tunnelling effects, which play a minor important role in the QCD sum rules, and are consistent with the small width of the $Z_c(3900)$. It is feasible to apply the QCD sum rules to study the tetraquark states, which begin to receive contributions at the order $\mathcal{O}({\alpha }_s^0)$, not at the order $\mathcal{O}({\alpha }_s^2)$.

    hep-phInt.J.Mod.Phys.A(2020)·24 citations
12. 12*

    Extraction of gluon distributions from structure functions at small x in holographic QCD

    Akira Watanabe🇨🇳 · Takahiro Sawada🇯🇵 · Mei Huang🇨🇳

    We investigate the nucleon and pion gluon distribution functions in the framework of holographic QCD, focusing on the small Bjorken x region. Based on an approximate relation, the gluon distributions are extracted from structure functions of the unpolarized deep inelastic scattering which can be calculated with a holographic QCD model, assuming the Pomeron exchange. All the adjustable parameters of the model are determined with the HERA data of the proton structure functions. We explicitly show that the extracted proton gluon distribution is consistent with results of the recent global QCD analysis. The structure functions of the pion can be computed without any additional parameter, which enables us to predict its gluon distribution also. We find that the resulting pion gluon density is smaller than the proton's, and agrees with the recent global QCD analysis result within the uncertainties.

    hep-phhep-exnucl-exnucl-thPLB(2020)·29 citations
13. 13*

    Quark beam function at next-to-next-to-next-to-leading order in perturbative QCD in the generalized large-$N_c$ approximation

    Arnd Behring🇩🇪 · Kirill Melnikov🇩🇪 · Robbert Rietkerk🇩🇪 · Lorenzo Tancredi🇬🇧 · Christopher Wever🇩🇪

    We present the matching coefficient for the quark beam function at next-to-next-to-next-to-leading order in perturbative QCD in the generalized large $N_c$-approximation, $N_c\sim N_f\gg 1$. Although several refinements are still needed to make this result interesting for phenomenological applications, our computation shows that a fully-differential description of simple color singlet production processes at a hadron collider at N${}^3$LO in perturbative QCD is within reach.

    hep-phPRD(2019)·32 citations
14. 14*

    Conformal Freeze-In of Dark Matter

    Sungwoo Hong🇺🇸 · Gowri Kurup🇺🇸 · Maxim Perelstein🇺🇸

    We present the conformal freeze-in (COFI) scenario for dark matter production. At high energies, the dark sector is described by a gauge theory flowing towards a Banks-Zaks fixed point, coupled to the standard model via a non-renormalizable portal interaction. At the time when the dark sector is populated in the early universe, it is described by a strongly coupled conformal field theory. As the universe cools, cosmological phase transitions in the standard model sector, either electroweak or QCD, induce conformal symmetry breaking and confinement in the dark sector. One of the resulting dark bound states is stable on the cosmological time scales and plays the role of dark matter. With the Higgs portal, the COFI scenario provides a viable dark matter candidate with mass in a phenomenologically interesting 0.1-1 MeV range. With the quark portal, a dark matter candidate with mass around 1 keV is consistent with observations. Conformal bootstrap puts a non-trivial constraint on model building in this case.

    hep-phPRD(2020)·28 citations
15. 15*

    Power Counting the Small-$x$ Observables

    Zhong-Bo Kang🇺🇸 · Xiaohui Liu🇨🇳

    We emphasize the importance of applying power counting to the small-$x$ observables, which introduces novel soft contributions usually missing and allows for a unified treatment of the Balitsky-Kovchegov (BK) evolution and various Sudakov logarithms. We use $pA\to h(p_{h\perp })X$ at forward rapidity to highlight how the power counting yields a partonic cross section with collinear and soft sectors. We show how the kinematic constraints can be obtained in the soft sector without violating the power counting. We further show how one can resum the threshold Sudakov logarithms systematically to all orders in a re-factorized framework with additional collinear-soft contributions. Direct applications to other small-$x$ processes involving heavy particles, jet (sub-)observables and EIC physics are straightforward.

    hep-phhep-exnucl-exnucl-th13 citations
16. 16*

    Modifications to Plane Gravitational Waves from Minimal Lorentz Violation

    Rui Xu🇨🇳

    General Relativity predicts two modes for plane gravitational waves. When a tiny violation of Lorentz invariance occurs, the two gravitational wave modes are modified. We use perturbation theory to study the detailed form of the modifications to the two gravitational wave modes from the minimal Lorentz-violation coupling. The perturbation solution for the metric fluctuation up to the first order in Lorentz violation is discussed. Then, we investigate the motions of test particles under the influence of the plane gravitational waves with Lorentz violation. First-order deviations from the usual motions are found.

    ↳ gr-qchep-phSymmetry(2019)·9 citations
17. 17*

    Color halo scenario of charmonium-like hybrids

    Yunheng Ma🇨🇳 · Wei Sun🇺🇸 · Ying Chen🇨🇳 · Ming Gong🇨🇳 · Zhaofeng Liu🇨🇳

    The internal structures of $J^{PC}=1^{--},(0,1,2{)}^{-+}$ charmonium-like hybrids are investigated under lattice QCD in the quenched approximation. We define the Bethe-Salpeter wave function ${\Phi }_n(r)$ in the Coulomb gauge as the matrix element of a spatially extended hybrid-like operator $\bar{c}cg$ between the vacuum and $n$-th state for each $J^{PC}$ with $r$ being the spatial separation between a localized $\bar{c}c$ component and the chromomagnetic strength tensor. These wave functions exhibit some similarities for states with the aforementioned different quantum numbers, and their $r$-behaviors (no node for the ground states and one node for the first excited states) imply that $r$ can be a meaningful dynamical variable for these states. Additionally, the mass splittings of the ground states and first excited states of charmonium-like hybrids in these channels are obtained for the first time to be approximately 1.2-1.4 GeV. These results do not support the flux-tube description of heavy-quarkonium-like hybrids in the Born-Oppenheimer approximation. In contrast, a charmonium-like hybrid can be viewed as a "color halo" charmonium for which a relatively localized color octet $\bar{c}c$ is surrounded by gluonic degrees of freedom, which can readily decay into a charmonium state along with one or more light hadrons. The color halo picture is compatible with the decay properties of $Y(4260)$ and suggests LHCb and BelleII to search for $(0,1,2{)}^{-+}$ charmonium-like hybrids in ${\chi }_{c0,1,2}\eta$ and $J/\psi \omega (\varphi )$ final states.

    ↳ hep-lathep-exhep-phCPC(2021)·11 citations
18. 18*

    Ultraperipheral vs ordinary nuclear interactions

    I.M. Dremin🇷🇺

    It is argued that the cross sections of ultraperipheral interactions of heavy nuclei can become comparable in value to those of their ordinary hadronic interactions at high energies. Simple estimates of corresponding "preasymptotic energy thresholds" are provided.The~method of equivalent photons is compared with the perturbative approach. The~situation at NICA/FAIR energies is discussed.

    ↳ nucl-thhep-exhep-phnucl-exUniverse(2019)·5 citations
19. 19*

    Non-minimal dark sector physics and cosmological tensions

    Eleonora Di Valentino🇬🇧 · Alessandro Melchiorri🇮🇹 · Olga Mena🇪🇸 · Sunny Vagnozzi🇬🇧

    We explore whether non-standard dark sector physics might be required to solve the existing cosmological tensions. The properties we consider in combination are an interaction between the dark matter and dark energy components, and a dark energy equation of state $w$ different from that of the canonical cosmological constant $w=-1$. In principle, these two parameters are independent. In practice, to avoid early-time, superhorizon instabilities, their allowed parameter spaces are correlated. We analyze three classes of extended interacting dark energy models in light of the 2019 Planck CMB results and Cepheid-calibrated local distance ladder $H_0$ measurements of Riess et al. (R19), as well as recent BAO and SNeIa distance data. We find that in quintessence coupled dark energy models, where $w>-1$, the evidence for a non-zero coupling between the two dark sectors can surpass the $5\sigma$ significance. On the other hand, in phantom coupled dark energy models, there is no such preference for a non-zero dark sector coupling. All the models we consider significantly raise the value of the Hubble constant easing the $H_0$ tension. The addition of low-redshift BAO and SNeIa measurements leaves some residual tension with R19 but at a level that could be justified by a statistical fluctuation. Bayesian evidence considerations mildly disfavour both the coupled quintessence and phantom models, while mildly favouring a coupled vacuum scenario, even when late-time datasets are considered. We conclude that non-minimal dark energy cosmologies, such as coupled quintessence, phantom, or vacuum models, are still an interesting route towards softening existing cosmological tensions, even when low-redshift datasets and Bayesian evidence considerations are taken into account. (abstract severely abridged)

    ↳ astro-ph.COgr-qchep-phPRD(2020)·439 citations
20. 20*

    Exploring non-equilibrium quark-gluon plasma effects on charm transport coefficients

    Taesoo Song🇩🇪 · Pierre Moreau🇩🇪 · Joerg Aichelin🇫🇷 · Elena Bratkovskaya🇩🇪

    In this article we investigate how the drag coefficient $A$ and $\hat{q}$, the transverse momentum transfer by unit length, of charm quarks are modified if the QGP is not in complete thermal equilibrium using the dynamical quasi-particle model (DQPM) which reproduces both, the equation-of-state of the QGP and the spatial diffusion coefficient of heavy quarks as predicted by lattice QCD calculations. We study three cases: a) the QGP has an anisotropic momentum distribution of the partons which leads to an anisotropic pressure b) the QGP partons have higher or lower kinetic energies as compared to the thermal expectation value, and c) the QGP partons have larger or smaller pole masses of their spectral function as compared to the pole mass from the DQPM at the QGP temperature. In the last two cases we adjust the number density of partons to obtain the same energy density as in an equilibrated QGP. In the first scenario we find that if the transverse pressure exceeds the longitudinal one for small heavy quark momenta $A$ becomes larger and $\hat{q}$ smaller as compared to an isotropic pressure. For heavy quarks with large momentum both, $A$ and $\hat{q}$ , approach unity. If the partons have less kinetic energy or a smaller pole mass as compared to a system in equilibrium charm quarks lose more energy. In the former case $\hat{q}$ decreases whereas in the latter case it increases for charm quark with a low or intermediate transverse momentum. Thus each non-equilibrium scenario affects $A$ and $\hat{q}$ of charm quarks in a different way. The modifications in our scenarios are of the order 20-50\% at temperatures relevant for heavy ion reactions. These modifications have to be considered if one wants to determine these coefficients by comparing heavy ion data with theoretical predictions from viscous hydrodynamics or Langevin equations.

    ↳ nucl-thhep-phPRC(2020)·41 citations
21. 21*

    Cosmology with the thermal-kinetic Sunyaev-Zel'dovich effect

    William R. Coulton🇬🇧 · Atsuhisa Ota🇬🇧 · Alexander van Engelen🇺🇸

    Compton scattering of the cosmic microwave background (CMB) from hot ionized gas produces a range of effects, and the leading order effects are the kinetic and thermal Sunyaev Zel'dovich (kSZ and tSZ) effects. In the near future, CMB surveys will provide the precision to probe beyond the leading order effects. In this work we study the cosmological information content of the next order term which combines the tSZ and kSZ effects, hereafter called the thermal-kinetic Sunyaev Zel'dovich (tkSZ) effect. As the tkSZ effect has the same velocity dependence as the kSZ effect, it will also have many of the useful properties of the kSZ effect. However, it also has its own, unique spectral dependence, which allows it to be isolated from all other CMB signals. We show that with currently-envisioned CMB missions the tkSZ effect can be detected and can be used to reconstruct large scale velocity fields, with no appreciable bias from either the kSZ effect or other extragalactic foregrounds. Furthermore, since the relativistic corrections arise from the well-studied pressure of ionized gas, rather than the gas number density as in the kSZ effect, the degeneracy due to uncertain gas physics will be significantly reduced. Finally, for a very low-noise experiment the tkSZ effect will be measurable at higher precision than the kSZ.

    ↳ astro-ph.COastro-ph.GAhep-phPRL(2020)·17 citations
22. 22*

    Conformal $n$-point functions in momentum space

    Adam Bzowski🇸🇪 · Paul McFadden🇬🇧 · Kostas Skenderis🇬🇧

    We present a Feynman integral representation for the general momentum-space scalar $n$-point function in any conformal field theory. This representation solves the conformal Ward identities and features an arbitrary function of $n(n-3)/2$ variables which play the role of momentum-space conformal cross-ratios. It involves $(n-1)(n-2)/2$ integrations over momenta, with the momenta running over the edges of an $(n-1)$-simplex. We provide the details in the simplest non-trivial case (4-point functions), and for this case we identify values of the operator and spacetime dimensions for which singularities arise leading to anomalies and beta functions, and discuss several illustrative examples from perturbative quantum field theory and holography.

    ↳ hep-thcond-mat.stat-mechcond-mat.str-elhep-phPRL(2020)·116 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.