Tue·Jul 28, 2020Tuesday·July 28, 2020

1. 01*

   Lepton-jet Correlation in Deep Inelastic Scattering

   Xiaohui Liu🇨🇳 · Felix Ringer🇺🇸 · Werner Vogelsang🇩🇪 · Feng Yuan🇺🇸

   We study the lepton-jet correlation in deep inelastic scattering. We perform one-loop calculations for the spin averaged and transverse spin dependent differential cross sections depending on the total transverse momentum of the final state lepton and the jet. The transverse momentum dependent (TMD) factorization formalism is applied to describe the relevant observables. To show the physics reach of this process, we perform a phenomenological study for HERA kinematics and comment on an ongoing analysis of experimental data. In addition, we highlight the potential of this process to constrain small-$x$ dynamics.

   hep-phhep-exnucl-exPRD(2020)·61 citations
2. 02*

   Integral solutions to the one-loop renormalization-group equations for lepton flavor mixing parameters and the Jarlskog invariant

   Di Zhang🇨🇳

   Working in the basis where the charged-lepton Yukawa matrix is diagonal and making the $\tau$-dominance approximations, we analytically derive integral solutions to the one-loop renormalization-group equations (RGEs) for neutrino masses, flavor mixing angles, CP-violating phases and the Jarlskog invariant under the standard parametrization of the PMNS matrix in the standard model or its minimal supersymmetric extension for both Majorana and Dirac neutrinos. With these integral solutions, we carry out numerical calculations to investigate the RGE running of lepton flavor mixing parameters and the Jarlskog invariant, and also compare these integral solutions with the exact results obtained by numerically solving the one-loop RGEs. It is shown that these integral solutions coincide with the exact results and can well describe the evolution of lepton flavor mixing parameters and the Jarlskog invariant in most cases. Some important features of our integral solutions and the evolution behaviors of relevant flavor parameters are also discussed in detail both analytically and numerically.

   hep-phhep-exNPB(2020)·16 citations
3. 03*

   Distinguishing Leptoquarks at the LHC/FCC

   Priyotosh Bandyopadhyay🇮🇳 · Saunak Dutta🇮🇳 · Mahesh Jakkapu🇯🇵 · Anirban Karan🇮🇳

   In this article, we deal with how to distinguish the signatures of different \LQs at the LHC/FCC if all of them lie within similar mass and coupling range and can be produced at present and future colliders. It has been found that hard scattering cross-sections and angular distributions can be used to differentiate scalar and vector Leptoquarks. On the other hand, final state topology and determination of jet charge can separate \LQs with same spin even from same $SU(2{)}_L$ multiplet. We performed a PYTHIA8 based analysis considering all the dominant Standard Model (SM) backgrounds at the LHC/FCC with centre of mass energies of 14, 27 and 100 TeV for scalar ($S_1$) and vector (${\tilde{U}}_{1\mu }$) Leptoquarks. We see that confirming evidence of scalar Leptoquark at 14 TeV requires 1000 fb${}^{-1}$ of integrated luminosity, whereas the vector Leptoquark can be probed with very early data. But, at 100 TeV with 1000 fb${}^{-1}$ of integrated luminosity, scalar Leptoquark of mass 3.5 TeV and vector Leptoquark of mass more than 5 TeV can be probed easily.

   hep-phNPB(2021)·23 citations
4. 04*

   Explaining Xenon-1T signal with FIMP dark matter and neutrino mass in a $U(1{)}_X$ extension

   Sarif Khan🇩🇪

   In the present work, we have extended the standard model by an abelian $U(1{)}_X$ gauge group and additional particles. In particular, we have extended the particle content by three right handed neutrinos, two singlet scalars and two vector like leptons. Charged assignments under different gauge groups are such that the model is gauge anomaly free and the anomaly contributions cancel among generations. Once the symmetry gets broken then three physical Higgses are produced, one axion like particle (ALP), which also acts as the keV scale FIMP dark matter, is produced and the remaining component is absorbed by the extra gauge boson. Firstly, we have successfully generated neutrino mass by the type-I seesaw mechanism for normal hierarchy with the $3\sigma$ bound on the oscillation parameters. The ALP in the present model can explain the Xenon-1T electron recoil signal at keV scale through its coupling with the electron. We also have vector like leptons which help in producing the dark matter from their decay by the freeze in mechanism. Electron and tauon get mass from dimensional-5 operators at Planck scale and if we consider the vevs $v_{1,2}\simeq 10^{12}$ GeV then we can obtain the correct value of the electron mass but not the tauon mass. Vector like leptons help in getting the correct value of the tauon mass through another higher dimensional operator which also has a role in DM production by the $2\to 2$ process, giving the correct ballpark value of relic density for suitable reheat temperature of the Universe. We have shown that the ALP production by the higher dimensional operator can explain the electron, tauon mass and Xenon-1T signal simultaneously whereas the decay production can not explain all of them together.

   hep-phEPJC(2021)·9 citations
5. 05*

   Effect of the anomalous magnetic moment of quarks on magnetized QCD matter and meson spectra

   Kun Xu🇨🇳 · Jingyi Chao🇨🇳 · Mei Huang🇨🇳

   We systematically investigate the effect of the anomalous magnetic moment(AMM) of quarks on the magnetized QCD matter, including the magnetic susceptibility, the inverse magnetic catalysis around the critical temperature and the neutral/charged pion and rho meson spectra under magnetic fields. The dynamical AMM of quarks, its coupling with magnetic field causes Zeeman splitting of the dispersion relation of quarks thus changes the magnetism properties and meson mass spectra under magnetic fields. It is found that including the AMM of quarks cannot fully understand lattice results of the magnetized matter: The AMM of quarks reduces the dynamical quark mass thus causes the inverse magnetic catalysis around $T_c$. The neutral pion mass is very sensitive to the AMM, it decreases with magnetic field quickly, and the charged pion mass shows a nonlinear behavior, i.e., firstly linearly increases with the magnetic field and then saturates at strong magnetic field. For rho meson, it is observed that AMM reduces the mass of neutral rho meson mass with different $s_z$, and reduces the mass of $s_z=+1,0$ component charged rho meson mass but enhances the $s_z=-1$ component charged rho meson mass. The magnetic susceptibility at low temperature can be either positive or negative with different AMM.

   hep-phPRD(2021)·71 citations
6. 06*

   Determination of the masses and decay widths of the scalar-isoscalar and vector-isovector mesons below $2$ GeV

   Evangelos Matsinos

   This study revisits the issue of the extraction of estimates for the masses and for the partial decay widths to two pions of the scalar-isoscalar $I^G(J^{PC})=0^{+}(0^{++})$ and vector-isovector $I^G(J^{PC})=1^{+}(1^{--})$ mesons below $2$ GeV, from the data contained in the recent compilation by the Particle Data Group.

   hep-phnucl-th4 citations
7. 07*

   Is $f_X(1500)$ observed in the $B\to \pi (K)KK$ decays ${\rho }^0(1450)$?

   Zhi-Tian Zou🇨🇳 · Ying Li🇨🇳 · Hsiang-nan Li🇹🇼

   We suggest that the uncertain state $f_X(1500)$ observed by Belle and BaBar more than a decade ago, which has been viewed as a single scalar or a combination of several even spin resonances, is the vector ${\rho }^0(1450)$ reported recently by LHCb. Adopting the perturbative QCD approach, we determine the di-kaon distribution amplitudes with the ${\rho }^0(1450)$ resonance from the LHCb data for the quasi-two-body decays $B^{\pm }\to {\pi }^{\pm }{\rho }^0(1450)\to {\pi }^{\pm }{K}^{+}{K}^{-}$. It is then shown that the $B^{+}\to K^{+}{K}^{+}{K}^{-}$ decay spectrum around the invariant mass $M(K^{+}{K}^{-})\sim 1.5\mathrm{GeV}$ measured by BaBar can be well described by the resonant contribution from ${\rho }^0(1450)$. The broad structure in the $B^{+}\to K^{+}{K}_S{K}_S$ spectrum around the invariant mass $1.5\mathrm{GeV}$ of a $K_S{K}_S$ pair, which ${\rho }^0(1450)$ cannot decay into because of Bose-Einstein statistics, can be accounted for by a nonresonant $S$-wave contribution alone. The branching fractions and/or the direct $CP$ asymmetries of the $B^{\pm }\to {\pi }^{\pm }{\rho }^0(1450)\to {\pi }^{\pm }{K}^{+}{K}^{-}$, $B^{+}\to K^{+}{\rho }^0(1450)\to K^{+}{K}^{+}{K}^{-}$ and $B^0\to K^0{\rho }^0(1450)\to K^0{K}^{+}{K}^{-}$ modes are predicted, which can be tested at the ongoing LHCb and Belle-II experiments. We encourage experimental colleagues to scrutinize our postulation by analyzing relevant data with higher precision.

   hep-phhep-exPRD(2021)·16 citations
8. 08*

   Complete $E_8$ Unification in 10 Dimensions

   Alfredo Aranda🇲🇽 · Francisco J. de Anda🇲🇽

   A grand unification model with a single $E_8$ gauge superfield in 10 dimensions is presented. It is shown that, through the orbifold $T^6/({\mathbb{Z}}_6\times {\mathbb{Z}}_2)$ and its corresponding Wilson lines, the symmetry is broken to the Standard Model one. Furthermore it is shown that the model is anomaly free at all levels without the need to add any extra field content. Thus a complete unification of the Standard Model into a single gauge superfield is achieved consistently.

   hep-phInt.J.Mod.Phys.A(2021)·6 citations
9. 09*

   Magic square and Dirac flavor neutrino mass matrix

   Yuta Hyodo🇯🇵 · Teruyuki Kitabayashi🇯🇵

   The magic texture is one of the successful textures of the flavor neutrino mass matrix for the Majorana type neutrinos. The name "magic" is inspired by the nature of the magic square. We estimate the compatibility of the magic square with the Dirac, instead of the Majorana, flavor neutrino mass matrix. It turned out that some parts of the nature of the magic square are appeared approximately in the Dirac flavor neutrino mass matrix and the magic squares prefer the normal mass ordering rather than the inverted mass ordering for the Dirac neutrinos.

   hep-phInt.J.Mod.Phys.A(2020)·7 citations
10. 10*

    Charged Current Drell-Yan Production at N3LO

    Claude Duhr🇨🇭 · Falko Dulat🇺🇸 · Bernhard Mistlberger🇺🇸

    We present the production cross section for a lepton-neutrino pair at the Large Hadron Collider computed at next-to-next-to-next-to leading order (N3LO) in QCD perturbation theory. We compute the partonic coefficient functions of a virtual $W^{\pm }$ boson at this order. We then use these analytic functions to study the progression of the perturbative series in different observables. In particular, we investigate the impact of the newly obtained corrections on the inclusive production cross section of $W^{\pm }$ bosons, as well as on the ratios of the production cross sections for $W^{+}$, $W^{-}$ and/or a virtual photon. Finally, we present N3LO predictions for the charge asymmetry at the LHC.

    hep-phJHEP(2020)·171 citations
11. 11*

    Scale and quality of Peccei-Quinn symmetry and weak gravity conjectures

    Wen Yin🇯🇵

    The promising solution to the strong CP problem by a Peccei-Quinn (PQ) symmetry may introduce quality and hierarchy problems, which are both relevant to Planck physics. In this paper, we study whether both problems can be explained by introducing a simple hidden gauge group that satisfies a weak gravity conjecture (WGC) or its variant. As a concrete example, we point out that a weakly-coupled hidden $SU(N)$ gauge symmetry, which is broken down to $SO(N)$, can do this job in the context of a Tower/sub-Lattice WGC. Cosmology is discussed.

    hep-phhep-thJHEP(2020)·33 citations
12. 12*

    Simulating hadron test beams in liquid argon

    Alexander Friedland (SLAC)🇺🇸 · Shirley Weishi Li (SLAC)🇺🇸

    Thorough modeling of the physics involved in liquid argon calorimetry is essential for accurately predicting the performance of DUNE and optimizing its design and analysis pipeline. At the fundamental level, it is essential to quantify the detector response to individual hadrons---protons, charged pions, and neutrons---at different injection energies. We report such a simulation, analyzed under different assumptions about event reconstruction, such as particle identification and neutron detection. The role of event containment is also quantified. The results of this simulation can help inform the ProtoDUNE test-beam data analysis, while also providing a framework for assessing the impact of various cross section uncertainties.

    hep-phhep-exnucl-exnucl-thPRD(2020)·12 citations
13. 13*

    Tau Neutrinos with Cherenkov Telescope Array

    Damiano F. G. Fiorillo🇮🇹 · Gennaro Miele🇮🇹 · Ofelia Pisanti🇮🇹

    The next generation of Imaging Atmospheric Cherenkov telescope, like CTA, is going to strongly improve the detection capability of high-energy cosmic rays. In our paper we discuss the possibility to use such apparatus to detect Earth-skimming tau neutrinos. Interestingly the analysis shows that order few events per year can be detected for energies above $10^8$ GeV in the optimistic case of larger neutrino fluxes produced by Flat Spectrum Radio Quasars. However, even for more conservative cosmogenic neutrino fluxes such rate will be also obtained, but for a decade of running. This estimate seems to candidate a set up like CTA for performing high energy neutrino astronomy as well.

    hep-phastro-ph.HE6 citations
14. 14*

    Effect of momentum anisotropy on quark matter in the quark-meson model

    He-Xia Zhang🇨🇳 · Ben-Wei Zhang🇨🇳

    We investigate the chiral phase structure of quark matter with spheroidal momentum-space anisotropy specified by one anisotropy parameter $\xi$ in the 2+1 flavor quark-meson model. We find that the chiral phase diagram and the location of the critical endpoint (CEP) are affected significantly by the value of $\xi$. With the increase of $\xi$, the CEP is shifted to smaller temperatures and larger quark chemical potentials. And the temperature of the CEP is more sensitive to the anisotropy parameter than the corresponding quark chemical potential, which is opposite to the study for finite system volume effect. Furthermore, the effects of momentum anisotropy on the thermodynamic properties and scalar (pseudoscalar) meson masses are also studied at vanishing quark chemical potential. The numerical results show that an increase of $\xi$ can hinder the restoration of chiral symmetry. We also find that shear viscosity and electrical conductivity decrease as $\xi$ grows. However, bulk viscosity exhibits a significant non-trivial behavior with $\xi$ in the entire temperature domain of interest.

    hep-phnucl-thCPC(2021)·5 citations
15. 15*

    Coherent and incoherent $J/\Psi$ photoproduction in $PbPb$ collisions at the LHC, HE -- LHC and FCC

    Victor P. Goncalves🇧🇷 · Daniel E. Martins🇧🇷 · Celso R. Sena🇧🇷

    The coherent and incoherent $J/\Psi$ photoproduction in $PbPb$ collisions are investigated considering the possible states of nucleon configurations in the nuclear wave function and taking into account of the non - linear corrections to the QCD dynamics. The cross sections and the rapidity and transverse momentum distributions are estimated for the energies of the next run of the LHC, High -- Energy LHC and Future Circular Collider. Our results indicate that a future experimental analysis of these processes will be useful to discriminate between different approaches for the QCD dynamics as well to improve our description of the gluon saturation effects.

    hep-phhep-exnucl-thEPJA(2021)·13 citations
16. 16*

    Resonant contributions to three-body $B_{(s)}\to [D^{(\ast )},{\bar{D}}^{(\ast )}]K^{+}{K}^{-}$ decays in the perturbative QCD approach

    Ya Li🇨🇳 · Da-Cheng Yan🇨🇳 · Zhou Rui🇨🇳 · Lan Liu🇨🇳 · Yue-Tong Zhang🇨🇳 · Zhen-Jun Xiao🇨🇳

    In this work, we study the $S$, $P$ and $D$ wave resonance contributions to three-body decays $B_{(s)}\to [D^{(\ast )},{\bar{D}}^{(\ast )}]K^{+}{K}^{-}$ by employing the perturbative QCD (PQCD) approach, where the kaon-kaon invariant mass spectra are dominated by the $f_0(980),f_0(1370),$ $\varphi (1020),\varphi (1680),f_2(1270),f_2^{\prime }(1525),f_2(1750)$ and $f_2(1950)$ resonances. The $KK$ $S$-wave component $f_0(980)$ is modeled with the Flatté formalism, while other resonances are described by the relativistic Breit-Wigner (BW) line shape. The corresponding decay channels are studied by constructing the kaon-kaon distribution amplitude ${\Phi }_{KK}$, which captures important final state interactions between the kaon pair in the resonant region. We found that the PQCD predictions for the branching ratios for most considered decays agree with currently available data within errors. The associated polarization fractions of those vector-vector and vector-tensor decay modes are also predicted, which are expected to be tested in the near future experiments. The invariant mass spectra for the corresponding resonances in the $B_{(s)}\to [D^{(\ast )},{\bar{D}}^{(\ast )}]K^{+}{K}^{-}$ decays are well established, which can be confronted with the precise data from the LHCb and Belle II experiments.

    hep-phhep-exPRD(2020)·12 citations
17. 17*

    Universality-breaking effects in $e^{+}{e}^{-}$ hadronic production processes

    M. Boglione🇮🇹 · A. Simonelli🇮🇹

    Recent BELLE measurements provide the cross section for single hadron production in $e^{+}{e}^{-}$ annihilations, differential in thrust and in the hadron transverse momentum with respect to the thrust axis. Universality breaking effects due to process-dependent soft factors make it very difficult to relate this cross sections to those corresponding to hadron-pair production in $e^{+}{e}^{-}$ annihilations, where transverse momentum dependent (TMD) factorization can be applied. The correspondence between these two cross sections is examined in the framework of the Collins-Soper-Sterman factorization, in the collinear as well as in the TMD approach. We propose a scheme that allows to relate the TMD parton densities defined in 1-hadron and in 2-hadron processes, neatly separating, within the soft and collinear parts, the non-perturbative terms from the contributions that can be calculated perturbatively. The regularization of rapidity divergences introduces cut-offs, the arbitrariness of which will be properly reabsorbed by means of a mechanism closely reminiscent of a gauge transformation. In this way, we restore the possibility to perform global phenomenological studies of TMD physics, simultaneously analyzing data belonging to different hadron classes.

    hep-phEPJC(2021)·22 citations
18. 18*

    Evolution of the Primordial Axial Charge across Cosmic Times

    A. Boyarsky🇳🇱 · V. Cheianov🇳🇱 · O. Ruchayskiy🇩🇰 · O. Sobol🇨🇭

    We investigate collisional decay of the axial charge in an electron-photon plasma at temperatures 10 MeV - 100 GeV. We demonstrate that the decay rate of the axial charge is first order in the fine-structure constant ${\Gamma }_{\mathrm{flip}}\propto \alpha m_e^2/T$ and thus orders of magnitude greater than the naive estimate which has been in use for decades. This counterintuitive result arises through infrared divergences regularized at high temperature by environmental effects. The decay of axial charge plays an important role in the problems of leptogenesis and cosmic magnetogenesis.

    hep-phastro-ph.COhep-thPRL(2021)·33 citations
19. 19*

    Half-integral weight modular forms and application to neutrino mass models

    Xiang-Gan Liu🇨🇳 · Chang-Yuan Yao🇨🇳 · Bu-Yao Qu🇨🇳 · Gui-Jun Ding🇨🇳

    We generalize the modular invariance approach to include the half-integral weight modular forms. Accordingly the modular group should be extended to its metaplectic covering group for consistency. We introduce the well-defined half-integral weight modular forms for congruence subgroup $\Gamma (4N)$ and show that they can be decomposed into the irreducible multiplets of finite metaplectic group ${\tilde{\Gamma }}_{4N}$. We construct concrete expressions of the half-integral/integral modular forms for $\Gamma (4)$ up to weight 6 and arrange them into the irreducible representations of ${\tilde{\Gamma }}_4$. We present three typical models with ${\tilde{\Gamma }}_4$ modular symmetry for neutrino masses and mixing, and the phenomenological predictions of each model are analyzed numerically.

    hep-phPRD(2020)·73 citations
20. 20*

    Implications of dark sector mixing on leptophilic scalar dark matter

    Sreemanti Chakraborti🇮🇳 · Rashidul Islam🇮🇳

    We propose a new viable outlook to the mixing between a singlet and a doublet leptonic dark sector fields. This choice relaxes the dark matter (DM) search constraints on the quintessential scalar singlet DM as well as presents new opportunities for its detection in the lab. The mixing produces an arbitrary mass difference between the two components of the extra doublet in a gauge-invariant way, without introducing any new scale of electroweak symmetry breaking in the theory. It also provides a useful handle to distinguish between the dark sector particles of different isospins, which is a challenging task otherwise. As the dark leptons coannihilate non-trivially, the mixing effectively enhances the viable parameter space for the relic density constraint. In low DM mass regime, our analysis shows that with a non-zero mixing, it is possible to relax the existing indirect search bounds on the upper limit of the DM-Standard Model coupling. From the analysis of the $3\tau +E_T^{miss}$ and $\ell \tau +E_T^{miss}$ channels for LHC at $\sqrt{s}=13$ TeV, we show that one ensures the presence of the mixing parameter between the dark sector particles of the theory by looking at the peak and tail positions of the kinematic distributions. Even with a tweak in the values of other free parameters within the viable parameter region, the distinct peak and tail positions of the kinematic distributions remains a constant feature of the model. While both the channels present us the opportunity to detect the mixing signature at the LHC/HL-LHC, the former gives better results in terms of a larger region of mixing parameter. From the fiducial cross section, the projected statistical significance for the integrated luminosity, $\mathcal{L}=3{\text{ab}}^{-1}$, are shown for a combined parameter region obeying all the existing constraints, where there is the best possibility to detect such a signature.

    hep-phJHEP(2021)·9 citations
21. 21*

    Accounting for the Heisenberg and Pauli principles in the kinetic approach to neutrino oscillations

    A. Kartavtsev🇷🇺

    While oscillations of solar neutrinos are usually studied using the single-particle quantum-mechanical approach, flavor conversions of supernovae neutrinos are typically analyzed using the kinetic equation for the matrix of densities due to the necessity of including also the scattering processes. Using the Wigner formulation of quantum mechanics we show the equivalence of the quantum-mechanical and kinetic approaches in the limit of collisionless neutrino propagation (in a background medium). Based on this observation we also argue that solutions of the kinetic equation account for the Heisenberg uncertainty principle and the related effect of wave packet separation (for single neutrinos), as well as the Pauli exclusion principle, if the initial conditions are consistent with these fundamental quantum principles. Such initial conditions can be constructed e.g. by identifying the matrix of densities with the (reduced) single-particle Wigner function computed using initial conditions for the neutrino wave function. Hence the neutrino momentum uncertainty is an integral part of the initial conditions for the matrix of densities, that may have an impact on the phenomenology of supernovae neutrinos via the effect of wave packet separation.

    hep-phJHEP(2020)·1 citation
22. 22*

    Fundamental physics with the diffuse supernova background neutrinos

    André de Gouvêa🇺🇸 · Ivan Martinez-Soler🇺🇸 · Yuber F. Perez-Gonzalez🇺🇸 · Manibrata Sen🇺🇸

    The Universe is awash with tens-of-MeV neutrinos of all species coming from all past core-collapse supernovae. These have never been observed, but this state of affairs will change in the near future. In the less than ten years, the Super-Kamiokande experiment, loaded with gadolinium, is expected to collect dozens of events induced by the scattering of neutrinos from the diffuse supernova neutrino background (DSNB). Next-generation projects, including Hyper-Kamiokande and Theia, are expected to collect data samples with hundreds of DSNB events after a decade of running. Here, we study quantitatively how well the DSNB, including its energy spectrum, will be measured by different current or upcoming large neutrino detectors. We analyze the simulated data in order to estimate how well measurements of the DSNB can be used to inform research topics in cosmology -- including measurements of the Hubble parameter -- astrophysics -- including the star-formation-rate -- and particle physics -- including the neutrino lifetime and the possibility that neutrinos are pseudo-Dirac fermions.

    hep-phastro-ph.COastro-ph.SRhep-exPRD(2020)·95 citations
23. 23*

    Dark Matter Substructure under the Electron Scattering Lamppost

    Jatan Buch🇺🇸 · Manuel A. Buen-Abad🇺🇸 · JiJi Fan🇺🇸 · John Shing Chau Leung🇺🇸

    We study the mutual relationship between dark matter-electron scattering experiments and possible new dark matter substructure nearby hinted by the Gaia data. We show how kinematic substructure could affect the average and modulation spectra of dark matter-electron scattering in semiconductors, and the discovery reaches of future experiments with these targets. Conversely, we demonstrate how future data could probe and constrain the substructure dark matter fraction, even when it constitutes a sub-dominant component of the local dark matter density.

    hep-phastro-ph.COastro-ph.GAPRD(2020)·18 citations
24. 24*

    Discovering partonic rescattering in light nucleus collisions

    Alexander Huss🇨🇭 · Aleksi Kurkela🇨🇭 · Aleksas Mazeliauskas🇨🇭 · Risto Paatelainen🇨🇭 · Wilke van der Schee🇨🇭 · Urs Achim Wiedemann🇨🇭

    We demonstrate that oxygen-oxygen (OO) collisions at the LHC provide unprecedented sensitivity to parton energy loss in a system whose size is comparable to those created in very peripheral heavy-ion collisions. With leading and next-to-leading order calculations of nuclear modification factors, we show that the baseline in the absence of partonic rescattering is known with up to 2% theoretical accuracy in inclusive OO collisions. Surprisingly, a $Z$-boson normalized nuclear modification factor does not lead to higher theoretical accuracy within current uncertainties of nuclear parton distribution functions. We study a broad range of parton energy loss models and we find that the expected signal of partonic rescattering can be disentangled from the baseline by measuring charged hadron spectra in the range $20\text{GeV}<p_T<100\text{GeV}$

    hep-phhep-exnucl-exnucl-thPRL(2021)·73 citations
25. 25*

    Two-loop Beta Function for Complex Scalar Electroweak Multiplets

    Joachim Brod🇺🇸 · Zachary Polonsky🇺🇸

    We present the general form of the renormalizable four-point interactions of a complex scalar field furnishing an irreducible representation of SU(2), and derive a set of algebraic identities that facilitates the calculation of higher-order radiative corrections. As an application, we calculate the two-loop beta function for the SM extended by a scalar multiplet, and provide the result explicitly in terms of the group invariants. Our results include the evolution of the Higgs-portal couplings, as well as scalar "minimal dark matter". We present numerical results for the two-loop evolution of the various couplings.

    hep-phhep-thJHEP(2020)·8 citations
26. 26*

    Predicting parton energy loss in small collision systems

    Alexander Huss🇨🇭 · Aleksi Kurkela🇨🇭 · Aleksas Mazeliauskas🇨🇭 · Risto Paatelainen🇨🇭 · Wilke van der Schee🇨🇭 · Urs Achim Wiedemann🇨🇭

    Medium induced parton energy loss is not conclusively established neither in very peripheral heavy-ion collisions nor in proton-ion collisions. However, the standard interpretation of azimuthal momentum anisotropies in theses systems implies some partonic rescattering. The upcoming light-ion runs at the LHC provide a unique opportunity to search for parton energy loss in different systems of similar size. Here, we make predictions for the expected parton energy loss signal in the charged hadron spectra in a system size scan at LHC. We test a large set of model assumptions against the transverse momentum and centrality dependence of the charged hadron nuclear modification factor in lead-lead and xenon-xenon collisions at the LHC. We then attempt to make a model agnostic prediction for the charged hadron nuclear modification factor in oxygen-oxygen collisions.

    hep-phhep-exnucl-exnucl-thPRC(2021)·84 citations
27. 27*

    Low Scale $U(1{)}_X$ Gauge Symmetry as an Origin of Dark Matter, Neutrino Mass and Flavour Anomalies

    Debasish Borah🇮🇳 · Lopamudra Mukherjee🇮🇳 · Soumitra Nandi🇮🇳

    We study a generic leptophilic $U(1{)}_X$ extension of the standard model with a light gauge boson. The $U(1{)}_X$ charge assignments for the leptons are guided by lepton universality violating (LUV) observables in semileptonic $b\to s\ell \ell$ decays, muon anomalous magnetic moment and the origin of leptonic masses and mixing. Anomaly cancellation conditions require the addition of new chiral fermions in the model, one of which acts as a dark matter (DM) candidate when it is stabilised by an additional ${\mathcal{Z}}_2$ symmetry. From our analysis, we show two different possible models with similar particle content that lead to quite contrasting neutrino mass origin and other phenomenology. The proposed models also have the potential to address the anomalous results in $b\to c\ell {\nu }_{\ell }$ decays like $R(D),R(D^{\ast })$, electron anomalous magnetic moment and the very recent KOTO anomaly in the kaon sector. We also discuss different possible collider signatures of our models which can be tested in future.

    hep-phhep-exJHEP(2020)·34 citations
28. 28*

    Potential of SKA to Detect CDM ALPs with Radio Astronomy

    Ahmed Ayad🇿🇦 · Geoff Beck🇿🇦

    Axion-like particles (ALPs) are light pseudo-scalar particles predicted in many theoretically well-motivated extensions to the standard model of particle physics (SM). The search for cold dark matter (CDM) ALPs has gained tremendous ground over the last few years. Essentially ALPs are characterized by their coupling with two photons which allows ALPs to decay into two photons. In this work, we explore the potential of the Square Kilometer Array (SKA) to detect CDM ALPs with radio astronomy in an attempt to detect an observational signature of ALPs conversion onto photons in astrophysical field.

    hep-phastro-ph.HE2 citations
29. 29*

    The fate of hints: updated global analysis of three-flavor neutrino oscillations

    Ivan Esteban🇪🇸 · M.C. Gonzalez-Garcia🇪🇸 · Michele Maltoni🇪🇸 · Thomas Schwetz🇩🇪 · Albert Zhou🇩🇪

    Our herein described combined analysis of the latest neutrino oscillation data presented at the Neutrino2020 conference shows that previous hints for the neutrino mass ordering have significantly decreased, and normal ordering (NO) is favored only at the $1.6\sigma$ level. Combined with the ${\chi }^2$ map provided by Super-Kamiokande for their atmospheric neutrino data analysis the hint for NO is at $2.7\sigma$. The CP conserving value ${\delta }_{\text{CP}}=180^{\circ }$ is within $0.6\sigma$ of the global best fit point. Only if we restrict to inverted mass ordering, CP violation is favored at the $\sim 3\sigma$ level. We discuss the origin of these results - which are driven by the new data from the T2K and NOvA long-baseline experiments -, and the relevance of the LBL-reactor oscillation frequency complementarity. The previous $2.2\sigma$ tension in $\Delta m_{21}^2$ preferred by KamLAND and solar experiments is also reduced to the $1.1\sigma$ level after the inclusion of the latest Super-Kamiokande solar neutrino results. Finally we present updated allowed ranges for the oscillation parameters and for the leptonic Jarlskog determinant from the global analysis.

    hep-phhep-exJHEP(2020)·1667 citations
30. 30*

    Modeling few-body resonances in finite volume

    Peng Guo🇺🇸

    Under the assumption of separable interactions, we illustrate how the few-body quantization condition may be formulated in terms of phase shifts in general, which may be useful for describing and modeling of few-body resonances in finite volume.

    ↳ hep-lathep-phPRD(2020)·35 citations
31. 31*

    Multiband gravitational-wave searches for ultralight bosons

    Ken K. Y. Ng🇺🇸 · Maximiliano Isi🇺🇸 · Carl-Johan Haster🇺🇸 · Salvatore Vitale🇺🇸

    Gravitational waves may be one of the few direct observables produced by ultralight bosons, conjectured dark matter candidates that could be the key to several problems in particle theory, high-energy physics and cosmology. These axionlike particles could spontaneously form "clouds" around astrophysical black holes, leading to potent emission of continuous gravitational waves that could be detected by instruments on the ground and in space. Although this scenario has been thoroughly studied, it has not been yet appreciated that both types of detector may be used in tandem (a practice known as "multibanding"). In this paper, we show that future gravitational-wave detectors on the ground and in space will be able to work together to detect ultralight bosons with masses $25\lesssim \mu /\left(10^{-15}\mathrm{eV}\right)\lesssim 500$. In detecting binary-black-hole inspirals, the LISA space mission will provide crucial information enabling future ground-based detectors, like Cosmic Explorer or Einstein Telescope, to search for signals from boson clouds around the individual black holes in the observed binaries. We lay out the detection strategy and, focusing on scalar bosons, chart the suitable parameter space. We study the impact of ignorance about the system's history, including cloud age and black hole spin. We also consider the tidal resonances that may destroy the boson cloud before its gravitational signal becomes detectable by a ground-based follow-up. Finally, we show how to take all of these factors into account, together with uncertainties in the LISA measurement, to obtain boson mass constraints from the ground-based observation facilitated by LISA.

    ↳ gr-qcastro-ph.HEhep-phPRD(2020)·49 citations
32. 32*

    Domain walls and other defects in Eddington-inspired Born-Infeld gravity

    P. P. Avelino🇵🇹 · L. Sousa🇵🇹

    We investigate domain wall and other defect solutions in the weak-field limit of Eddington-inspired Born-Infeld gravity as a function of $\kappa$, the only additional parameter of the theory with respect to General Relativity. We determine, both analytically and numerically, the internal structure of domain walls, quantifying its dependency on $\kappa$ as well as the impact of such dependency on the value of the tension measured by an outside observer. We find that the pressure in the direction perpendicular to the domain wall can be, in contrast to the weak-field limit of General Relativity, significantly greater or smaller than zero, depending, respectively, on whether $\kappa$ is positive or negative. We further show that the generalized von Laue condition, which states that the average value of the perpendicular pressure is approximately equal to zero in the weak-field limit of General Relativity, does not generally hold in EiBI gravity not only for domain walls, but also in the case cosmic strings and spherically symmetric particles. We argue that a violation of the generalized von Laue condition should in general be expected in any theory of gravity whenever geometry plays a significant role in determining the defect structure.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2020)·4 citations
33. 33*

    Lifting Heptagon Symbols to Functions

    Lance J. Dixon🇺🇸 · Yu-Ting Liu🇺🇸

    Seven-point amplitudes in planar $\mathcal{N}=4$ super-Yang-Mills theory have previously been constructed through four loops using the Steinmann cluster bootstrap, but only at the level of the symbol. We promote these symbols to actual functions, by specifying their first derivatives and boundary conditions on a particular two-dimensional surface. To do this, we impose branch-cut conditions and construct the entire heptagon function space through weight six. We plot the amplitudes on a few lines in the bulk Euclidean region, and explore the properties of the heptagon function space under the coaction associated with multiple polylogarithms.

    ↳ hep-thhep-phJHEP(2020)·65 citations
34. 34*

    Importance of Multiplicity Fluctuations in Entropy Scaling

    Patrick Carzon🇺🇸 · Matthew D. Sievert🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸

    One of the greatest uncertainties in heavy-ion collisions is the description of the initial state. Different models predict a wide range of initial energy density distributions based on their underlying assumptions. Final flow harmonics are sensitive to these differences in the initial state due to the nearly linear mapping between eccentricities and anisotropic flow harmonics. The Trento code uses a model-agnostic approach by phenomenologically parameterizing the initial state and constraining those parameters from a Bayesian analysis. There the multiplicity fluctuations were determined by a one parameter $\Gamma$ distribution. However, initial-state models arising from the Color-Glass Condensate (CGC) framework lead to an initial energy density which is outside the functional form considered in Trento and its later Bayesian analyses because they rely on log-normal multiplicity fluctuations. We compare $T_A{T}_B$ scaling (CGC-like) to $\sqrt{T_A{T}_B}$ scaling (preferred from a Trento Bayesian analysis) and find that the $T_A{T}_B$ form together with log-normal fluctuations is a reasonable candidate to describe the multiplicity fluctuations but leads to larger eccentricities, which would affect the extraction of viscosity in small systems.

    ↳ nucl-thhep-phnucl-exPoS(2021)·5 citations
35. 35*

    The strong CP problem, general covariance, and horizons

    Giorgio Torrieri🇧🇷 · Henrique Dias Truran🇧🇷

    We discuss the strong CP problem in the context of quantum field theory in the presence of horizons. We argue that general covariance places constraints on the topological structure of the theory. In particular, as in QCD, it means that different topological sectors of the theory can only sum incoherently, because the degrees of freedom beyond the horizon must be traced over for general covariance to apply. This might lead to a solution of the so-called strong CP problem without extra observable dynamics.

    ↳ hep-thgr-qchep-phClass.Quant.Grav.(2021)·6 citations
36. 36*

    Holographic theories at finite $\theta$-angle, CP-violation, glueball spectra and strong-coupling instabilities

    Yuta Hamada🇫🇷 · Elias Kiritsis🇬🇷 · Francesco Nitti🇫🇷

    A general class of holographic theories with a nontrivial $\theta$-angle are analyzed. The instanton density operator is dual to a bulk axion field. We calculate the ground-state solutions with nontrivial source, $a_{UV}$, for the axion, for both steep and soft dilaton potentials in the IR, and both in $d=3$ and $d=4$. We find all cases to be qualitatively similar. We also calculate the spin$=2,0$ glueball spectra and show that the glueball masses monotonically decrease as functions of $a_{UV}$ (or $\theta$-angle). The slopes of glueball masses are different, generically, in different potentials. In the case of steep dilaton potentials, the glueball (masses)${}^2$ turn negative before the maximum of $a_{UV}$ is attained. We interpret this as a signal for a favored instanton condensation in the bulk. We also investigate strong CP-violation in the effective glueball action.

    ↳ hep-thhep-lathep-phFortsch.Phys.(2021)·8 citations
37. 37*

    Real scalar field stars of the EKG equations including matter

    Alejandro Cabo Montes de Oca🇨🇺 · Duvier Suarez Fontanella🇨🇺

    Static (not stationary) solutions of the Einstein-Klein-Gordon (EKG) equations including matter are obtained for real scalar fields. The scalar field interaction with matter is considered. The introduced coupling allows the existence of static solutions in contraposition with the case of the simpler EKG equations for real scalar fields and gravity. Surprisingly, when the considered matter is a photon-like gas, it turns out that the gravitational field intensity at large radial distances becomes nearly a constant, exerting an approximately fixed force to small bodies at any distance. The effect is clearly related with the massless character of the photon-like field. It is also argued that the gravitational field can generate a bounding attraction, that could avoid the unlimited increase in mass with the radius of the obtained here solution. This phenomenon, if verified, may furnish a possible mechanism for explaining how the increasing gravitational potential associated to dark matter, finally decays at large distances from the galaxies. A method for evaluating these photon bounding effects is just formulated in order to be further investigated.

    ↳ gr-qcastro-ph.GAhep-phInt.J.Mod.Phys.D(2021)·3 citations
38. 38*

    Two-Pion-Exchange contributions to the nucleon-nucleon interactions in covariant baryon chiral perturbation theory

    Yang Xiao🇨🇳 · Chun-Xuan Wang🇨🇳 · Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳

    Employing the covariant baryon chiral perturbation theory, we calculate the leading and next-to-leading order two-pion exchange (TPE) contributions to $NN$ interaction up to order $O(p^3)$. We compare the so-obtained $NN$ phase shifts with $2\le L\le 6$ and mixing angles with $2\le J\le 6$ with those obtained in the nonrelativistic baryon chiral perturbation theory, which allows us to check the relativistic corrections to the medium-range part of $NN$ interactions. We show that the contributions of relativistic TPE are more moderate than those of the nonrelativistic TPE. The relativistic corrections play an important role in F-waves especially the ${}^3{\text{F}}_2$ partial wave. Moreover, the relativistic results seem to converge faster than the nonrelativistic results in almost all the partial waves studied in the present work, consistent with the studies performed in the one-baryon sector.

    ↳ nucl-thhep-phPRC(2020)·19 citations
39. 39*

    Graph Neural Networks in Particle Physics

    Jonathan Shlomi🇮🇱 · Peter Battaglia🇬🇧 · Jean-Roch Vlimant🇺🇸

    Particle physics is a branch of science aiming at discovering the fundamental laws of matter and forces. Graph neural networks are trainable functions which operate on graphs---sets of elements and their pairwise relations---and are a central method within the broader field of geometric deep learning. They are very expressive and have demonstrated superior performance to other classical deep learning approaches in a variety of domains. The data in particle physics are often represented by sets and graphs and as such, graph neural networks offer key advantages. Here we review various applications of graph neural networks in particle physics, including different graph constructions, model architectures and learning objectives, as well as key open problems in particle physics for which graph neural networks are promising.

    ↳ hep-exhep-phMach.Learn.Sci.Tech.(2020)·208 citations
40. 40*

    Sequential Discontinuities of Feynman Integrals and the Monodromy Group

    Jacob L. Bourjaily🇩🇰 · Holmfridur Hannesdottir🇺🇸 · Andrew J. McLeod🇩🇰 · Matthew D. Schwartz🇺🇸 · Cristian Vergu🇩🇰

    We generalize the relation between discontinuities of scattering amplitudes and cut diagrams to cover sequential discontinuities (discontinuities of discontinuities) in arbitrary momentum channels. The new relations are derived using time-ordered perturbation theory, and hold at phase-space points where all cut momentum channels are simultaneously accessible. As part of this analysis, we explain how to compute sequential discontinuities as monodromies and explore the use of the monodromy group in characterizing the analytic properties of Feynman integrals. We carry out a number of cross-checks of our new formulas in polylogarithmic examples, in some cases to all loop orders.

    ↳ hep-thhep-phJHEP(2021)·85 citations
41. 41*

    Chiral gravitational waves and primordial black holes in UV-protected Natural Inflation

    Juan P. Beltrán Almeida🇨🇴 · Nicolás Bernal🇨🇴 · Dario Bettoni🇪🇸 · Javier Rubio🇫🇮

    We consider an UV-protected Natural Inflation scenario involving Chern-Simons-like interactions between the inflaton and some beyond the Standard Model gauge fields. The accelerated expansion of the Universe is supported by a combination of a gravitationally-enhanced friction sensitive to the scale of inflation and quantum friction effects associated with the explosive production of gauge fluctuations. The synergy of these two velocity-restraining mechanisms allows for: $i)$ Natural Inflation potentials involving only sub-Planckian coupling constants, $ii)$ the generation of a dark matter component in the form of primordial black holes, and $iii)$ a potentially observable background of chiral gravitational waves at small scales.

    ↳ astro-ph.COgr-qchep-phJCAP(2020)·21 citations
42. 42*

    Diversity of dark matter density profiles in the Galactic dwarf spheroidal satellites

    Kohei Hayashi🇯🇵 · Masashi Chiba🇯🇵 · Tomoaki Ishiyama🇯🇵

    The core-cusp problem is one of the controversial issues in the standard paradigm of $\Lambda$ cold dark matter ($\Lambda$CDM) theory. However, under the assumption of conventional spherical symmetry, the strong degeneracy among model parameters makes it unclear whether dwarf spheroidal (dSph) galaxies indeed have cored dark matter density profiles at the centers. In this work, we revisit this problem using non-spherical mass models, which have the advantage of being able to alleviate the degeneracy. Applying our mass models to the currently available kinematic data of the eight classical dSphs, we find that within finite uncertainties, most of these dSphs favor cusped central profiles rather than cored ones. In particular, Draco has a cusped dark matter halo with high probability even considering a prior bias. We also find the diversity of the inner slopes in their dark matter halos. To clarify the origin of this diversity, we investigate the relation between the inner dark matter density slope and stellar-to-halo mass ratio for the sample dSphs and find this relation is generally in agreement with the predictions from recent $\Lambda$CDM and hydrodynamical simulations. We also find that the simulated subhalos have anti-correlation between the dark matter density at 150 pc and pericenter distance, which is consistent with the observed one. We estimate their astrophysical factors for dark matter indirect searches and circular velocity profiles, associated with huge uncertainties. To more precisely estimate their dark matter profiles, wide-field spectroscopic surveys for the dSphs are essential.

    ↳ astro-ph.GAastro-ph.COhep-phApJ(2020)·115 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.