Tue·Jun 30, 2020Tuesday·June 30, 2020

1. 01*

   Improved $(g-2{)}_{\mu }$ Measurements and Supersymmetry

   Manimala Chakraborti🇪🇸 · Sven Heinemeyer🇪🇸 · Ipsita Saha🇯🇵

   The electroweak (EW) sector of the Minimal Supersymmetric Standard Model (MSSM) can account for a variety of experimental data. The lighest supersymmetric particle (LSP), which we take as the lightest neutralino, ${\tilde{\chi }}_1^0$, can account for the observed Dark Matter (DM) content of the universe via coannihilation with the next-to-LSP (NLSP), while being in agreement with negative results from Direct Detection (DD) experiments. Owing to relatively small production cross-sections a comparably light EW sector of the MSSM is also in agreement with the unsuccessful searches at the LHC. Most importantly, the EW sector of the MSSM can account for the persistent $3-4\sigma$ discrepancy between the experimental result for the anomalous magnetic moment of the muon, $(g-2{)}_{\mu }$, and its Standard Model (SM) prediction. Under the assumption that the ${\tilde{\chi }}_1^0$ provides the full DM relic abundance we first analyze which mass ranges of neutralinos, charginos and scalar leptons are in agreement with all experimental data, including relevant LHC searches. We find an upper limit of $\sim 600$ GeV for the LSP and NLSP masses. In a second step we assume that the new result of the Run 1 of the ``MUON G-2'' collaboration at Fermilab yields a precision comparable to the existing experimental result with the same central value. We analyze the potential impact of the combination of the Run 1 data with the existing $(g-2{)}_{\mu }$ data on the allowed MSSM parameter space. We find that in this case the upper limits on the LSP and NLSP masses are substantially reduced by roughly $100$ GeV. This would yield improved upper limits on these masses of $\sim 500$ GeV. In this way, a clear target could be set for future LHC EW searches, as well as for future high-energy $e^{+}{e}^{-}$ colliders, such as the ILC or CLIC.

   hep-phEPJC(2020)·56 citations
2. 02*

   Probing BFKL dynamics at hadronic colliders in jet gap jet events

   F. Deganutti🇺🇸 · C. Royon🇺🇸

   In this report, we give the Balitsky Fadin Kuraev Lipton formalism for jet gap jet events at hadronic colliders. We also discuss the case where in addition at least one proton is intact in the final state in diffractive events.

   hep-phEPJ Web Conf.(2020)·3 citations
3. 03*

   Exploring color-octet scalar parameter space in minimal $R$-symmetric models

   Linda M. Carpenter🇺🇸 · Taylor Murphy🇺🇸 · Matthew J. Smylie🇺🇸

   In this work we study the collider phenomenology of color-octet scalars (sgluons) in minimal supersymmetric models endowed with a global continuous $R$ symmetry. We systematically catalog the significant decay channels of scalar and pseudoscalar sgluons and identify novel features that are natural in these models. These include decays in nonstandard diboson channels, such as to a gluon and a photon; three-body decays with considerable branching fractions; and long-lived particles with displaced vertex signatures. We also discuss the single and pair production of these particles and show that they can evade existing constraints from the Large Hadron Collider, to varying extents, in large regions of reasonable parameter space. We find, for instance, that a 725 GeV scalar and a 350 GeV or lighter pseudoscalar can still be accommodated in realistic scenarios.

   hep-phJHEP(2020)·18 citations
4. 04*

   High order chiral Lagrangians with vector mesons in different approaches

   Wei Guo🇨🇳 · Qin-He Yang🇨🇳 · Shao-Zhou Jiang🇨🇳

   The chiral Lagrangians with vector mesons are constructed in different approaches, including the next-to-leading order Lagrangian in the vector-field approach, the next-to-next-to-leading order Lagrangians in the tensor-field and the hidden local symmetry approaches. Some redundant terms are found at the next-to-leading order in the tensor-field and the hidden local symmetry approaches. The corresponding relations between the next-to-next-to-leading order pseudoscalar mesonic low-energy constants and the ones in the hidden local symmetry approach are obtained at tree level. The equivalence between the tensor-field approach and the hidden local symmetry approach is also discussed.

   hep-ph2 citations
5. 05*

   Two-body charmed baryon decays involving decuplet baryon in the quark-diagram scheme

   Y.K. Hsiao🇨🇳 · Qian Yi🇨🇳 · Shu-Ting Cai🇨🇳 · H.J. Zhao🇨🇳

   In the quark-diagram scheme, we study the charmed baryon decays of ${\mathbf{B}}_c\to {\mathbf{B}}^{\ast }M$, where ${\mathbf{B}}_c$ is ${\Lambda }_c^{+}$ or ${\Xi }_c^{+(0)}$, together with ${\mathbf{B}}^{\ast }$ ($M$) the decuplet baryon (pseudoscalar meson). It is found that only two $W$-exchange processes are allowed to contribute to ${\mathbf{B}}_c\to {\mathbf{B}}^{\ast }M$. Particularly, we predict $\mathcal{B}({\Lambda }_c^{+}\to {\Sigma }^{\ast 0(+)}{\pi }^{+(0)})=(2.8\pm 0.4)\times 10^{-3}$, which respects the isospin symmetry. Besides, we take into account the $SU(3)$ flavor symmetry breaking, in order to explain the observation of $\mathcal{B}({\Lambda }_c^{+}\to {\Sigma }^{\ast +}\eta )$. For the decays involving ${\Delta }^{++}(uuu)$, we predict $\mathcal{B}({\Lambda }_c^{+}\to {\Delta }^{++}{\pi }^{-},{\Xi }_c^{+}\to {\Delta }^{++}{K}^{-})=(7.0\pm 1.4,13.5\pm 2.7)\times 10^{-4}$ as the largest branching fractions in the singly Cabibbo-suppressed ${\Lambda }_c^{+},{\Xi }_c^{+}\to {\mathbf{B}}^{\ast }M$ decay channels, respectively, which are accessible to the LHCb, BELLEII and BESIII experiments.

   hep-phhep-exEPJC(2020)·27 citations
6. 06*

   Excitation Functions of Tsallis-like Parameters in High-Energy Nucleus-Nucleus Collisions

   Li-Li Li🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿

   The transverse momentum spectra of charged pions, kaons, and protons produced at mid-rapidity in central nucleus-nucleus (AA) collisions at high energies are analyzed by considering particles to be created from two participant partons which are assumed to be contributors from the collision system. Each participant (contributor) parton is assumed to contribute to the transverse momentum by a Tsallis-like function. The contributions of the two participant partons are regarded as the two components of transverse momentum of the identified particle. The experimental data measured in high-energy AA collisions by international collaborations are studied. The excitation functions of kinetic freeze-out temperature and transverse flow velocity are extracted. The two parameters increase quickly from $\approx 3$ to $\approx 10$ GeV (exactly from 2.7 to 7.7 GeV) and then slowly at above 10 GeV with the increase of collision energy. In particular, there is a plateau from near 10 GeV to 200 GeV in the excitation function of kinetic freeze-out temperature.

   hep-phhep-exnucl-exnucl-thEntropy(2021)·31 citations
7. 07*

   One-loop vertex correction in a plane wave

   A. Di Piazza🇩🇪 · M. A. Lopez-Lopez🇺🇸

   We compute the general expression of the one-loop vertex correction in an arbitrary plane-wave background field for the case of two on-shell external electrons and an off-shell external photon. The properties of the vertex corrections under gauge transformations of the plane-wave background field and of the radiation field are studied. Concerning the divergences of the vertex correction, the infrared one is cured by assigning a finite mass to the photon, whereas the ultraviolet one is shown to be renormalized exactly as in vacuum. Finally, the corresponding expression of the vertex correction within the locally-constant crossed field is also derived and the high-field asymptotic is shown to scale according to the Ritus-Narozhny conjecture.

   hep-phPRD(2020)·25 citations
8. 08*

   The mass scales of the Higgs field

   Maurizio Consoli🇮🇹 · Leonardo Cosmai🇮🇹

   In the first version of the theory, with a classical scalar potential, the sector inducing SSB was distinct from the Higgs field interactions induced through its gauge and Yukawa couplings. We have adopted a similar perspective but, following most recent lattice simulations, described SSB in $\lambda {\Phi }^4$ theory as a weak first-order phase transition. In this case, the resulting effective potential has two mass scales: i) a lower mass $m_h$, defined by its quadratic shape at the minima, ~and~ ii) a larger mass $M_h$, defined by the zero-point energy. These refer to different momentum scales in the propagator and are related by $M_h^2\sim m_h^2\ln ({\Lambda }_s/M_h)$, where ${\Lambda }_s$ is the ultraviolet cutoff of the scalar sector. We have checked this two-scale structure with lattice simulations of the propagator and of the susceptibility in the 4D Ising limit of the theory. These indicate that, in a cutoff theory where both $m_h$ and $M_h$ are finite, by increasing the energy, there could be a transition from a relatively low value, e.g. $m_h$=125 GeV, to a much larger $M_h$. The same lattice data give a final estimate $M_h=720\pm 30$ GeV which induces to re-consider the experimental situation at LHC. In particular an independent analysis of the ATLAS + CMS data indicating an excess in the 4-lepton channel as if there were a new scalar resonance around 700 GeV. Finally, the presence of two vastly different mass scales, requiring an interpolating form for the Higgs field propagator also in loop corrections, could reduce the discrepancy with those precise measurements which still favor large values of the Higgs particle mass.

   hep-phInt.J.Mod.Phys.A(2020)·19 citations
9. 09*

   A Dyson-Schwinger model beyond isospin limit prepared for investigating U_A(1)-breaking temperature dependence

   Davor Horvatić🇭🇷 · Dalibor Kekez🇭🇷 · Dubravko Klabučar🇭🇷

   Motivated by our earlier findings of sensitive quark-flavor dependence of QCD topological susceptibility on products of current quark masses and corresponding condensates, we allow the breaking of isospin symmetry. For the purpose of future investigations of U_A(1) symmetry breaking and restoration at T > 0, we perform (at T = 0) refitting of the quark-mass parameters of a phenomenologically successful effective model of low-energy QCD. It belongs to the class of separable-interaction models within the Dyson-Schwinger approach to the quark-antiquark substructure of mesons.

   hep-phnucl-thEur.Phys.J.ST(2020)·3 citations
10. 10*

    From prompt to direct J/$\psi$ production: new insights on the ${\chi }_{c1}$ and ${\chi }_{c2}$ polarizations and feed-down contributions from a global-fit analysis of mid-rapidity LHC data

    Pietro Faccioli🇵🇹 · Carlos Lourenço🇨🇭 · Thomas Madlener🇩🇪

    While the prompt J/$\psi$ cross section and polarization have been measured with good precision as a function of transverse momentum, $p_{\mathrm{T}}$, those of the directly produced J/$\psi$ are practically unknown, given that the cross sections and polarizations of the ${\chi }_{c1}$ and ${\chi }_{c2}$ mesons, large indirect contributors to J/$\psi$ production, are only known with rather poor accuracy. The lack of precise measurements of the ${\chi }_{cJ}$ polarizations induces large uncertainties in the level of their feed-down contributions to the prompt J/$\psi$ yield, because of the polarization-dependent acceptance corrections. The experimental panorama of charmonium production can be significantly improved through a consistent and model-independent global analysis of existing measurements of J/$\psi$, $\psi$(2S) and ${\chi }_c$ cross sections and polarizations, faithfully respecting all the correlations and uncertainties. In particular, it is seen that the ${\chi }_{cJ}$ polarizations and feed-down fractions to J/$\psi$ production have a negligible dependence on the J/$\psi$ $p_{\mathrm{T}}$, with average values ${\lambda }_{\vartheta }^{{\chi }_{c1}}=0.55\pm 0.23$, ${\lambda }_{\vartheta }^{{\chi }_{c2}}=-0.39\pm 0.22$, $R^{{\chi }_{c1}}=(18.8\pm 1.4)\%$ and $R^{{\chi }_{c2}}=(6.5\pm 0.5)\%$. The analysis also shows that $(67.2\pm 1.9)\%$ of the prompt J/$\psi$ yield is due to directly-produced mesons, of polarization constrained to remarkably small values, ${\lambda }_{\vartheta }^{\mathrm{J}/\psi }=0.04\pm 0.06$.

    hep-phEPJC(2020)·10 citations
11. 11*

    FeynOnium: Using FeynCalc for automatic calculations in Nonrelativistic Effective Field Theories

    Nora Brambilla🇩🇪 · Hee Sok Chung🇩🇪 · Vladyslav Shtabovenko🇩🇪 · Antonio Vairo🇩🇪

    We present new results on FeynOnium, an ongoing project to develop a general purpose software toolkit for semi-automatic symbolic calculations in nonrelativistic Effective Field Theories (EFTs). Building upon FeynCalc, an existing Mathematica package for symbolic evaluation of Feynman diagrams, we have created a powerful framework for automatizing calculations in nonrelativistic EFTs (NREFTs) at tree- and 1-loop level. This is achieved by exploiting the novel features of FeynCalc that support manipulations of Cartesian tensors, Pauli matrices and nonstandard loop integrals. Additional operations that are common in nonrelativistic EFT calculations are implemented in a dedicated add-on called FeynOnium. While our current focus is on EFTs for strong interactions of heavy quarks, extensions to other systems that admit a nonrelativistic EFT description are planned for the future. All our codes are open-source and publicly available. Furthermore, we provide several example calculations that demonstrate how FeynOnium can be employed to reproduce known results from the literature.

    hep-phcond-mat.str-elhep-lathep-th+1JHEP(2020)·23 citations
12. 12*

    Probing new physics effects in ${\Lambda }_b\to \Lambda (\to p{\pi }^{-}){\ell }^{+}{\ell }^{-}$ decay via model independent approach

    Aqsa Nasrullah🇵🇰 · Ishtiaq Ahmed🇵🇰 · M. Jamil Aslam🇵🇰 · Z. Asghar🇵🇰 · Saba Shafaq🇵🇰

    The New Physics (NP) effects are studied in the rare baryonic decay ${\Lambda }_b\to \Lambda (\to p{\pi }^{-}){\ell }^{+}{\ell }^{-}$, with unpolarized ${\Lambda }_b$ using most general model independent approach by introducing new axial(vector), (pseudo)scalar and tensor operators in the weak effective Hamiltonian corresponding to $b\to s$ transitions. Recently, for ${\Lambda }_b\to \Lambda (\to p{\pi }^{-}){\mu }^{+}{\mu }^{-}$ decay the LHCb collaboration has measured the branching ratio $(d\mathcal{B}/ds)$, lepton- and hadron-side forward-backward asymmetries, denoted by $A_{FB}^{\ell }$ and $A_{FB}^{\Lambda }$, respectively, and the longitudinal polarization fraction $F_L$ both in the low- and high-recoil regions. To see whether the new $VA$, $SP$ and $T$ couplings can accommodate the available experimental data of these observables, first we have examined their influence on these observables and later we have checked the imprints of these new couplings on a number of interesting but yet not measured observables. It is found that compared to the $VA$ the $SP$ couplings favor experimental data for all the four observables but still no individual coupling is able to accommodate all of the available data simultaneously. To achieve this goal, the pairs of new WCs are taken to check their range that simultaneously satisfy constraints of $B$-Physics and available LHCb data on $d\mathcal{B}/ds$, $F_L$, $A_{FB}^{\ell }$ and $A_{FB}^{\Lambda }$ in several bins for the decay channel under consideration. We find that most of the available data could be accommodated by the different pairs of $VA$ and $SP$ WCs giving more severe constraints on the parametric space of these WCs that is still satisfied with the $B$-physics data.

    hep-phPhys.Scripta(2021)·2 citations
13. 13*

    Study of production of (anti)deuteron observed in Au+Au collisions at $\sqrt{S_{NN}}$=14.5, 62.4 and 200 GeV

    Ying Yuan🇨🇳

    Transverse momentum distributions of deuterons and anti-deuterons in Au+Au collisions at $\sqrt{S_{NN}}$=14.5, 62.4 and 200 GeV with different centrality are studied in the framework of the multisource thermal model. Transverse momentum spectra are conformably and approximately described by the Tsallis distribution. The dependence of parameters (average transverse momenta, effective temperature and entropy index) on event centrality are obtained. It is found that the parameters increase with increase of the average number of particles involved in collisions, which reveals the nuclear stopping degree increases with collision centrality.

    hep-phAdv.High Energy Phys.(2021)·2 citations
14. 14*

    Theoretical study of the $\Omega (2012)$ state in the ${\Omega }_c^0\to {\pi }^{+}\Omega (2012{)}^{-}\to {\pi }^{+}(\bar{K}\Xi {)}^{-}$ and ${\pi }^{+}(\bar{K}\Xi \pi {)}^{-}$ decays

    Chun-Hua Zeng🇨🇳 · Jun-Xu Lu🇨🇳 · En Wang🇨🇳 · Ju-Jun Xie🇨🇳 · Li-Sheng Geng🇨🇳

    We report on a theoretical study of the newly observed $\Omega (2012)$ resonance in the nonleptonic weak decays of ${\Omega }_c^0\to {\pi }^{+}\bar{K}{\Xi }^{\ast }(1530)(\eta \Omega )\to {\pi }^{+}(\bar{K}\Xi {)}^{-}$ and ${\pi }^{+}(\bar{K}\Xi \pi {)}^{-}$ via final-state interactions of the $\bar{K}{\Xi }^{\ast }(1530)$ and $\eta \Omega$ pairs. The weak interaction part is assumed to be dominated by the charm quark decay process: $c(ss)\to (s+u+\bar{d})(ss)$, while the hadronization part takes place between the $sss$ cluster from the weak decay and a quark-antiquark pair with the quantum numbers $J^{PC}=0^{++}$ of the vacuum, produces a pair of $\bar{K}{\Xi }^{\ast }(1530)$ and $\eta \Omega$. Accordingly, the final $\bar{K}{\Xi }^{\ast }(1530)$ and $\eta \Omega$ states are in pure isospin $I=0$ combinations, and the ${\Omega }_c^0\to {\pi }^{+}\bar{K}{\Xi }^{\ast }(1530)(\eta \Omega )\to {\pi }^{+}(\bar{K}\Xi {)}^{-}$ decay is an ideal process to study the $\Omega (2012)$ resonance. With the final-state interaction described in the chiral unitary approach, up to an arbitrary normalization, the invariant mass distributions of the final state are calculated, assuming that the $\Omega (2012)$ resonance with spin-parity $J^P=3/2^{-}$ is a dynamically generated state from the coupled channels interactions of the $\bar{K}{\Xi }^{\ast }(1530)$ and $\eta \Omega$ in $s$-wave and $\bar{K}\Xi$ in $d$-wave. We also calculate the ratio, $R_{\bar{K}\Xi }^{\bar{K}\Xi \pi }=\mathrm{Br}[{\Omega }_c^0\to {\pi }^{+}\Omega (2012{)}^{-}\to {\pi }^{+}(\bar{K}\Xi \pi {)}^{-}]/\mathrm{Br}[{\Omega }_c^0\to {\pi }^{+}\Omega (2012{)}^{-}\to {\pi }^{+}(\bar{K}\Xi {)}^{-}$]. The proposed mechanism can provide valuable information on the nature of the $\Omega (2012)$ and can in principle be tested by future experiments.

    hep-phhep-exnucl-exnucl-thPRD(2020)·35 citations
15. 15*

    Direct detection of freeze-in inelastic dark matter

    Haipeng An🇨🇳 · Daneng Yang🇨🇳

    We show that the current sensitivities of direct detection experiments have already reached the interesting parameter space of freeze-in dark matter models if the dark sector is in the inelastic dark matter framework and the excited dark matter state is cosmologically stable. Using results recently presented by the XENON1T experiment, we present constraints on these models. We also show that these models can explain the reported excess in the electron recoil signals if the mass gap between the ground state and the excited state is at keV scale.

    hep-phastro-ph.HEhep-exPLB(2021)·59 citations
16. 16*

    In medium properties of axion within a Polyakov loop enhanced Nambu-Jona-Lasinio model

    Arpan Das🇵🇱 · Hiranmaya Mishra🇮🇳 · Ranjita K. Mohapatra🇮🇳

    We estimate the axion properties i.e. its mass, topological susceptibility and the self-coupling within the framework of Polyakov loop enhanced Nambu-Jona-Lasinio (PNJL) model at finite temperature and quark chemical potential. PNJL model, where quarks couple simultaneously to the chiral condensate and to a background temporal quantum chromodynamics (QCD) gauge field, includes two important features of QCD phase transition, i.e. deconfinement and chiral symmetry restoration. The Polyakov loop in PNJL model plays an important role near the critical temperature. We have shown significant difference in the axion properties calculated in PNJL model compared to the same obtained using Nambu-Jona-Lasinio (NJL) model. We find that both the mass of the axion and its self-coupling are correlated with the chiral transition as well as the confinement-deconfinement transition. We have also estimated the axion properties at finite chemical potential. Across the QCD transition temperature and/or quark chemical potential axion mass and its self-coupling also changes significantly. Since the PNJL model includes both the fermionic sector and the gauge fields, it can give reliable estimates of the axion properties, i.e. it's mass and the self-coupling in a hot and dense QCD medium. We also compare our results with the lattice QCD results whenever available.

    hep-phnucl-thPRD(2021)·19 citations
17. 17*

    Prompt photon production in high-energy $pA$ collisions at forward rapidity

    G. Sampaio dos Santos🇧🇷 · G. Gil da Silveira🇧🇷 · M. V. T. Machado🇧🇷

    Prompt photon production in hadronic collisions at the RHIC and the LHC energies is investigated within the QCD color dipole approach. Predictions for the nuclear modification factor in $pA$ collisions are evaluated based on parton saturation framework and the results are compared to the experimental measurements as a function of the photon transverse momentum at different rapidity bins. The reliability of the models is performed with the data from PHENIX, ATLAS, and ALICE Collaborations. Moreover, we show that the observed $x_T$-scaling of prompt photon production in $pp$ and $pA$ collisions can positively be addressed in the QCD color dipole formalism.

    hep-phhep-exPRC(2020)·12 citations
18. 18*

    Telling Solar Neutrinos from Solar Axions When You Can't Shut Off the Sun

    Pilar Coloma🇪🇸 · Patrick Huber🇺🇸 · Jonathan M. Link🇺🇸

    The XENON1T experiment recently reported an excess of events at low electron recoil energies, which may be due to interactions of solar neutrinos inside the detector via a large neutrino magnetic moment. We point out that a ${}^{51}$Cr neutrino source placed close to the detector can directly test this hypothesis.

    hep-phhep-exnucl-ex19 citations
19. 19*

    Experimental constraint on axion-like particle coupling over seven orders of magnitude in mass

    Tanya S. Roussy🇺🇸 · Daniel A. Palken🇺🇸 · William B. Cairncross🇺🇸 · Benjamin M. Brubaker🇺🇸 · Daniel N. Gresh🇺🇸 · Matt Grau🇺🇸 · Kevin C. Cossel🇺🇸 · Kia Boon Ng🇺🇸 · Yuval Shagam🇺🇸 · Yan Zhou🇺🇸 · Victor V. Flambaum🇦🇺 · Konrad W. Lehnert🇺🇸 · Jun Ye🇺🇸 · Eric A. Cornell🇺🇸

    We use our recent electric dipole moment (EDM) measurement data to constrain the possibility that the HfF${}^{+}$ EDM oscillates in time due to interactions with candidate dark matter axion-like particles (ALPs). We employ a Bayesian analysis method which accounts for both the look-elsewhere effect and the uncertainties associated with stochastic density fluctuations in the ALP field. We find no evidence of an oscillating EDM over a range spanning from 27 nHz to 400 mHz, and we use this result to constrain the ALP-gluon coupling over the mass range $10^{-22}-10^{-15}$ eV. This is the first laboratory constraint on the ALP-gluon coupling in the $10^{-17}-10^{-15}$ eV range, and the first laboratory constraint to properly account for the stochastic nature of the ALP field.

    hep-phastro-ph.COphysics.atom-phPRL(2021)·100 citations
20. 20*

    Semileptonic Decay of $D_s^{+}\to {\pi }^0{\ell }^{+}{\nu }_{\ell }$ Via Neutral Meson Mixing

    Hai-Bo Li🇨🇳 · Mao-Zhi Yang🇨🇳

    Based on the mechanism of neutral meson mixing, we predict the branching fraction of the semileptonic decay of $D_s^{+}\to {\pi }^0{\ell }^{+}{\nu }_{\ell }$ ($\ell =e$, $\mu$) using recently measured branching fraction of $D_s^{+}\to \eta e^{+}{\nu }_e$ by BESIII experiment . We also give a formula that can describe the neutral meson mixing of ${\pi }^0$, $\eta$, ${\eta }^{\prime }$ and a pseudoscalar gluonium $G$ in a unified way. The predicted branching fraction of $D_s^{+}\to {\pi }^0{e}^{+}{\nu }_e$ decay is $\mathcal{B}(D_s^{+}\to {\pi }^0{e}^{+}{\nu }_e)=(2.65\pm 0.38)\times 10^{-5}$. It is important to search for the decay $D_s^{+}\to {\pi }^0{\ell }^{+}{\nu }_{\ell }$ in experiment, in order to understand the mechanism of ${\pi }^0$ production in $D_s^{+}\to {\pi }^0$ transition in semileptonic decay. We also estimate the branching fraction of $D_s^{+}\to {\pi }^0{\tau }^{+}{\nu }_{\tau }$, which is the only kinematically allowed semi-tauonic decay mode of the charmed meson, since the mass value of $D_s^{+}$ meson is just slightly above the threshold of ${\pi }^0{\tau }^{+}$ generation in the semi-tauonic decay.

    hep-phhep-exPLB(2020)·5 citations
21. 21*

    Semi-annihilating $Z_3$ Dark Matter for XENON1T Excess

    P. Ko🇰🇷 · Yong Tang🇨🇳

    The recently reported result from XENON1T experiment indicates that there is an excess with $3.5\sigma$ significance in the electronic recoil events. Interpreted as new physics, new sources are needed to account for the electronic scattering. We show that a dark fermion $\psi$ with mass about $\mathcal{O}\left(10\right)$ MeV from semi-annihilation of $Z_3$ dark matter $X$ and subsequent decay of a dark gauge boson $V_{\mu }$ may be responsible for the excess. The relevant semi-annihilation process is $X+X\to \overline{X}+V_{\mu }(\to \psi +\overline{\psi })$, in which the final $\psi$ has a box-shape energy spectrum. The fast-moving $\psi$ can scatter with electron through an additional gauge boson that mixes with photon kinetically. The shape of the signals in this model can be consistent with the observed excess. The additional interaction with proton makes this model testable in future searches for nucleus recoil as well. Because of the lightness of invisible particle introduced, this scenario requires non-standard cosmology to accommodate the additional radiation component.

    hep-phastro-ph.COPLB(2021)·43 citations
22. 22*

    $Z$-boson decays into an invisible dark photon at the LHC, HL-LHC and future lepton colliders

    M. Cobal🇮🇹 · C. De Dominicis🇫🇷 · M. Fabbrichesi🇮🇹 · E. Gabrielli🇮🇹 · J. Magro🇮🇹 · B. Mele🇮🇹 · G. Panizzo🇮🇹

    We study the decay of the $Z$ vector boson into a photon and a massless (invisible) dark photon in high-energy collisions. The photon can be used as trigger for the event, while the dark photon is detected indirectly as missing momentum in the event final state. We investigate the possibility of searching for such a dark photon at the LHC, HL-LHC and future lepton colliders, and compare the respective sensitivities. As expected, the best result is found for the lepton colliders running at the $Z$ mass, FCC-ee and CEPC, with a final sensitivity to branching ratios of order $O(10^{-11})$. We also discuss how to use the photon angular distribution of the events in lepton collisions to discriminate between the dark photon and a pseudo-scalar state like the axion.

    hep-phhep-exPRD(2020)·15 citations
23. 23*

    Fermion and Photon gap-equations in Minkowski space within the Nakanishi Integral Representation method

    Cédric Mezrag🇫🇷 · Giovanni Salmè🇮🇹

    The approach based on the Nakanishi integral representation of n-leg transition amplitudes is extended to the treatment of the self-energies of a fermion and an (IR-regulated) vector boson, in order to pave the way for constructing a comprehensive application of the technique to both gap- and Bethe-Salpeter equations, in Minkowski space. The achieved result, namely a 6-channel coupled system of integral equations, eventually allows one to determine the three Källén-Lehman weights for fully dressing the propagators of fermion and photon. A first consistency check is also provided. The presented formal elaboration points to embed the characteristics of the non-perturbative regime at a more fundamental level. It yields a viable tool in Minkowski space for the phenomenological investigation of strongly interacting theories, within a QFT framework where the dynamical ingredients are made transparent and under control.

    hep-phnucl-thEPJC(2021)·26 citations
24. 24*

    Axion, Neutrinos Masses and $\mu$-Problem in Minimal Supersymmetric Standard Model (MSSM)

    M. C. Rodriguez🇧🇷

    We review very nice mechanism to generate masses to all the neutrinos in the Minimal Supersymmetric Standard Model (MSSM) without break $R$-parity. In consequence we get viable axion as Dark Matter candidate and at the same time solve the $\mu$-problem in a similar way as done in the Next to Minimal Supersymmetric Model (NMSSM).

    hep-ph1 citation
25. 25*

    Intrinsic charm in the nucleon and charm production at large rapidities in collinear, hybrid and $k_T$-factorization approaches

    Rafal Maciula🇵🇱 · Antoni Szczurek🇵🇱

    We discuss the role of intrinsic charm (IC) in the nucleon for forward production of $c$-quark (or $\bar{c}$-antiquark) in proton-proton collisions for low and high energies. The calculations are performed in collinear-factorization approach with on-shell partons, $k_T$-factorization approach with off-shell partons as well as in a hybrid approach using collinear charm distributions and unintegrated (transverse momentum dependent) gluon distributions. For the collinear-factorization approach we use matrix elements for both massless and massive charm quarks/antiquarks. The distributions in rapidity and transverse momentum of charm quark/antiquark are shown for a few different models of IC. Forward charm production is dominated by $gc$-fusion processes. The IC contribution dominates over the standard pQCD (extrinsic) $gg$-fusion mechanism of $c\bar{c}$-pair production at large rapidities or Feynman-$x_F$. We perform similar calculations within leading-order and next-to-leading order $k_T$-factorization approach. The $k_T$-factorization approach leads to much larger cross sections than the LO collinear approach. At high energies and large rapidities of $c$-quark or $\bar{c}$-antiquark one tests gluon distributions at extremely small $x$. The IC contribution has important consequences for high-energy neutrino production in the Ice-Cube experiment and can be, to some extent, tested at the LHC by the SHIP and FASER experiments by studies of the ${\nu }_{\tau }$ neutrino production.

    hep-phJHEP(2020)·23 citations
26. 26*

    Strong decays of fully-charm tetraquarks into di-charmonia

    Hua-Xing Chen🇨🇳 · Wei Chen🇨🇳 · Xiang Liu🇨🇳 · Shi-Lin Zhu🇨🇳

    We study strong decays of the possible fully-charm tetraquarks recently observed by LHCb, and calculate their relative branching ratios through the Fierz rearrangement. Together with our previous QCD sum rule study [Phys. Lett. B 773, 247 (2017)], our results suggest that the broad structure around $6.2$-$6.8$ GeV can be interpreted as an $S$-wave $cc\bar{c}\bar{c}$ tetraquark state with $J^{PC}=0^{++}$ or $2^{++}$, and the narrow structure around 6.9 GeV can be interpreted as a $P$-wave one with $J^{PC}=0^{-+}$ or $1^{-+}$. These structures were observed in the di-$J/\psi$ invariant mass spectrum, and we propose to confirm them in the di-${\eta }_c$, $J/\psi h_c$, ${\eta }_c{\chi }_{c0}$, and ${\eta }_c{\chi }_{c1}$ channels. We also propose to search for their partner states having the negative charge-conjugation parity in the $J/\psi {\eta }_c$, $J/\psi {\chi }_{c0}$, $J/\psi {\chi }_{c1}$, and ${\eta }_c{h}_c$ channels.

    hep-phhep-exSci.Bull.(2020)·102 citations
27. 27*

    Solar Neutrino Scattering with Electron into Massive Sterile Neutrino

    Shao-Feng Ge🇨🇳 · Pedro Pasquini🇨🇳 · Jie Sheng🇨🇳

    The recent Xenon1T excess can be explained by solar neutrino scattering with electron via a light mediator, either scalar or vector, in addition to many other explanations from the dark sector. Since only the recoil electron is observable, a keV sterile neutrino instead of an active neutrino can appear in the final state. The sterile neutrino allows pseudoscalar mediator to explain the Xenon1T excess which was thought impossible. In addition, nonzero recoil energy lower bound arises from the sterile neutrino mass, which can be used to testify if the sterile neutrino is massive or not. We also briefly discuss the case of a sterile neutrino final state with light $Z^{\prime }$ mediator.

    hep-phhep-exPLB(2020)·41 citations
28. 28*

    Impact of loop-induced processes on the boosted dark matter interpretation of the XENON1T excess

    Luigi Delle Rose🇮🇹 · Gert Hütsi🇪🇪 · Carlo Marzo🇪🇪 · Luca Marzola🇪🇪

    We consider the boosted dark matter solution of the XENON1T excess to constrain the framework through loop-generated processes. The interaction of the boosted dark matter component, which sources the signal, effectively couples the cold dark matter background to the electrons, making it potentially visible in the electron recoil searches. Similarly, once the radiative corrections due to the Standard Model are taken into account, dark matter also scatters on quarks and becomes observable in nuclear recoil measurements. By analysing these processes, we find that the current direct detection constraints exclude the upper mass range selected by the anomaly if the boosted component is generated through dark matter annihilation.

    hep-phJCAP(2021)·35 citations
29. 29*

    Contribution of the non-linear term in the Balitsky-Kovchegov equation to the nuclear structure functions

    Jan Cepila🇨🇿 · Marek Matas🇨🇿

    In this paper, we present nuclear structure functions calculated from the impact-parameter dependent solution of the Balitsky-Kovchegov equation with our recently proposed set of nuclear initial conditions. We calculate the results with and without the non-linear term in the BK equation in order to study the impact of saturation effects on the measurable structure functions and nuclear modification factor. The difference of these results rises with decreasing Bjorken $x$ and increasing scale. These predictions are of interest to the physics program at the future ep and eA colliders.

    hep-phEPJA(2020)·4 citations
30. 30*

    Self-interacting dark matter from late decays and the $H_0$ tension

    Andrzej Hryczuk🇵🇱 · Krzysztof Jodłowski🇵🇱

    We study a dark matter production mechanism based on decays of a messenger WIMP-like state into a pair of dark matter particles that are self-interacting via exchange of a light mediator. Its distinctive thermal history allows the mediator to be stable and therefore avoid strong limits from the cosmic microwave background and indirect detection. A natural by-product of this mechanism is a possibility of a late time, i.e., after recombination, transition to subdominant dark radiation component through three-body and one-loop decays to states containing the light mediator. We examine to what extent such a process can help to alleviate the $H_0$ tension. Additionally, the mechanism can provide a natural way of constructing dark matter models with ultra-strong self-interactions that may positively affect the supermassive black hole formation rate. We provide a simple realization of the mechanism in a Higgs portal dark matter model and find a significant region of the parameter space that leads to a mild relaxation of the Hubble tension while simultaneously having the potential of addressing small-scale structure problems of $\Lambda$CDM.

    hep-phastro-ph.COPRD(2020)·53 citations
31. 31*

    Pseudo-Dirac Dark Matter in XENON1T

    Wei Chao🇨🇳 · Yu Gao🇨🇳 · Ming jie Jin🇨🇳

    The XENON1T dark matter experiment recently reported 0.65 ton-year exposure measurement on electron recoils , which shows an excess in $2\sim 3$ KeV recoils above the detector background. In this paper we present a Pseudo-Dirac dark matter scenario to explain the excess via inelastic dark matter-electron scattering. With a KeV scale mass splitting between the two components of the Pseudo-Dirac dark matter, the slightly excited component can down-scatter on electrons. The desired dark matter masses are about 10 GeV with a 4 KeV mass-splitting and unity coupling to electrons, which generate the observed XENON1T recoil events, give the appropriate dark matter relic abundance and satisfy collider search limits.

    hep-ph35 citations
32. 32*

    XENON1T Excess: Some Possible Backgrounds

    Biplob Bhattacherjee🇮🇳 · Rhitaja Sengupta🇮🇳

    This work is a study of some possible background sources in the XENON1T environment which might affect the energy spectrum of electronic recoil events in the lower side and might contribute to the observed excess. We have identified some additional possible backgrounds, like ${}^{41}$Ca, ${}^{49}$V, ${}^{63}$Ni, ${}^{106}$Ru and ${}^{125}$Sb coming from cosmogenic production, where the former two emit monoenergetic $X$-rays and the latter three have $\beta$ decays, or isotopes, like ${}^{210}$Pb, from the decay chain of ${}^{222}$Rn emanated in liquid xenon from the materials, or isotopes, like ${}^{137}$Cs, produced due to neutron capture. We perform a ${\chi }^2$ fitting of the ER spectrum from these backgrounds along with tritium to the observed excess events by varying their individual rates to understand whether they can be present to contribute to the low energy excess or their presence is constrained from the data. We also study the possibility of simultaneous presence of more than one such backgrounds, and how this affects the rates required by individual backgrounds to explain the excess.

    hep-phhep-exPLB(2021)·33 citations
33. 33*

    Lepton Number Violating Electron Recoils in a $U(1{)}_{B-L}$ Model with Non-Standard Interactions

    Yugen Lin🇨🇳 · Yu Gao🇨🇳 · Tianjun Li🇨🇳

    We propose an $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y\times U(1{)}_{B-L}$ model, in which the neutrino masses and mixings can be generated via Type-I seesaw mechanism after $U(1{)}_{B-L}$ breaking. A light mediator emerges and enables non-standard interaction that violates the lepton number. We show that the non-standard neutrino interaction emerges in this model, and it can lead to low energy recoil events with the solar neutrino flux. Analyses are performed with the keV range electron recoil events at recent direct detection experiments, including XENON1T, PANDAX and XENONnT. Recent direct detection observations lead to upper bound on the combined coupling strength to electron and neutrino to $\sqrt{y_{\nu }^{\prime }{y}_e}<0.5\times 10^{-6}$.

    hep-phNPB(2023)·25 citations
34. 34*

    Systematics in the XENON1T data: the 15-keV anti-axion

    Christopher Dessert🇺🇸 · Joshua W. Foster🇺🇸 · Yonatan Kahn🇺🇸 · Benjamin R. Safdi🇺🇸

    The XENON1T collaboration has found an excess of electron recoil events in their Science Run 1 data below ~7 keV with a spectral shape consistent with that expected from a solar-axion-induced signal. The claimed statistical significance of the solar-axion model over the null hypothesis is 3.5$\sigma$. In this work we provide evidence for mismodeling in the electron recoil data that may decrease the local significance of the axion model to as low as $p\approx 0.1$. To reach this conclusion, we search for a signal with the spectral template of the solar axion model, but shifted to higher (unphysical) energies above ~7 keV. We find that the distribution of significances found from this side-band analysis does not follow the expected chi-square distribution, which allows us to quantify the extent to which mismodeling may be affecting the interpretation of the data at energies below ~7 keV. For example, we find that there is an even higher-significance fit to the data when the solar axion model is shifted upwards in energy by ~15 keV and allowed to have a negative normalization.

    hep-phhep-exPhys.Dark Univ.(2021)·24 citations
35. 35*

    Vector Leptoquarks Beyond Tree Level II: $\mathcal{O}({\alpha }_s)$ Corrections and Radial Modes

    Javier Fuentes-Martin🇨🇭 · Gino Isidori🇨🇭 · Matthias König🇨🇭 · Nudzeim Selimovic🇨🇭

    We clarify open issues in relating low- and high-energy observables, at next-to-leading order accuracy, in models with a massive leptoquark embedded in a flavor non-universal $SU(4)\times SU(3)\times SU(2)\times U(1)$ gauge group. Extending previous work on this subject, we present a complete analysis of the $\mathcal{O}({\alpha }_s)$ corrections to the matching conditions of semileptonic operators at the high scale. These corrections are not negligible, but they do not exceed the 10% level and are subleading compared to the $\mathcal{O}({\alpha }_4)$ corrections proportional to the leading leptoquark coupling, which is expected to be much larger than the QCD coupling in the parameter space region of phenomenological interest. We further analyze the impact of radial modes, both at $\mathcal{O}({\alpha }_4)$ and at $\mathcal{O}({\alpha }_s)$ accuracy, highlighting their role in the renormalization of the theory.

    hep-phPRD(2020)·45 citations
36. 36*

    Dark Matter Annihilation Can Produce a Detectable Antihelium Flux through ${\bar{\Lambda }}_b$ Decays

    Martin Wolfgang Winkler🇸🇪 · Tim Linden🇸🇪

    Recent observations by the Alpha Magnetic Spectrometer (AMS-02) have tentatively detected a handful of cosmic-ray antihelium events. Such events have long been considered as smoking-gun evidence for new physics, because astrophysical antihelium production is expected to be negligible. However, the dark-matter-induced antihelium flux is also expected to fall below current sensitivities, particularly in light of existing antiproton constraints. Here, we demonstrate that a previously neglected standard model process -- the production of antihelium through the displaced-vertex decay of ${\bar{\Lambda }}_b$-baryons -- can significantly boost the dark matter induced antihelium flux. This process can triple the standard prompt-production of antihelium, and more importantly, entirely dominate the production of the high-energy antihelium nuclei reported by AMS-02.

    hep-phastro-ph.GAastro-ph.HEPRL(2021)·51 citations
37. 37*

    Implications of the XENON1T Excess on the Dark Matter Interpretation

    Haider Alhazmi🇺🇸 · Doojin Kim🇺🇸 · Kyoungchul Kong🇺🇸 · Gopolang Mohlabeng🇺🇸 · Jong-Chul Park🇰🇷 · Seodong Shin🇰🇷

    The dark matter interpretation for a recent observation of excessive electron recoil events at the XENON1T detector seems challenging because its velocity is not large enough to give rise to recoiling electrons of $\mathcal{O}(\mathrm{keV})$. Fast-moving or boosted dark matter scenarios are receiving attention as a remedy for this issue, rendering the dark matter interpretation a possibility to explain the anomaly. We investigate various scenarios where such dark matter of spin 0 and 1/2 interacts with electrons via an exchange of vector, pseudo-scalar, or scalar mediators. We find parameter values not only to reproduce the excess but to be consistent with existing bounds. Our study suggests that the scales of mass and coupling parameters preferred by the excess can be mostly affected by the type of mediator, and that significantly boosted dark matter can explain the excess depending on the mediator type and its mass choice. The method proposed in this work is general, and hence readily applicable to the interpretation of observed data in the dark matter direct detection experiment.

    hep-phhep-exJHEP(2021)·50 citations
38. 38*

    Ellipticity of photon emission from strongly magnetized hot QCD plasma

    Xinyang Wang🇨🇳 · Igor A. Shovkovy🇺🇸 · Lang Yu🇨🇳 · Mei Huang🇨🇳

    By making use of an explicit representation for the imaginary part of the photon polarization tensor in terms of transitions between the Landau levels of light quarks, we study the angular dependence of direct photon emission from a strongly magnetized quark-gluon plasma. Because of the magnetic field, the leading order photon rate comes from the three processes of the zeroth order in the coupling constant ${\alpha }_s$: (i) the quark splitting ($q\to q+\gamma$), (ii) the antiquark splitting ($\bar{q}\to \bar{q}+\gamma$), and (iii) the quark-antiquark annihilation ($q+\bar{q}\to \gamma$). In a wide range of moderately high temperatures, $T\gtrsim m_{\pi }$, and strong magnetic fields, $|eB|\gtrsim m_{\pi }^2$, the direct photon production is dominated by the two splitting processes. We show that the Landau-level quantization of quark states plays an important role in the energy and angular dependence of the photon emission. Among other things, it leads to a nontrivial momentum dependence of the photon ellipticity coefficient $v_2$, which takes negative values at small transverse momenta and positive values at large transverse momenta. The crossover between the two regimes occurs around $k_T\simeq \sqrt{|eB|}$. In application to heavy-ion collisions, this suggests that a large value of $v_2$ for the direct photons could be explained in part by the magnetic field in the quark-gluon plasma.

    hep-phhep-thnucl-thPRD(2020)·56 citations
39. 39*

    The Fermionic Universal One-Loop Effective Action

    Sebastian A. R. Ellis🇺🇸 · Jérémie Quevillon🇫🇷 · Pham Ngoc Hoa Vuong🇫🇷 · Tevong You🇨🇭 · Zhengkang Zhang🇺🇸

    Recent development of path integral matching techniques based on the covariant derivative expansion has made manifest a universal structure of one-loop effective Lagrangians. The universal terms can be computed once and for all to serve as a reference for one-loop matching calculations and to ease their automation. Here we present the fermionic universal one-loop effective action (UOLEA), resulting from integrating out heavy fermions with scalar, pseudo-scalar, vector and axial-vector couplings. We also clarify the relation of the new terms computed here to terms previously computed in the literature and those that remain to complete the UOLEA. Our results can be readily used to efficiently obtain analytical expressions for effective operators arising from heavy fermion loops.

    hep-phhep-thJHEP(2020)·62 citations
40. 40*

    XENON1T solar axion and the Higgs boson emerging from the dark

    Giacomo Cacciapaglia🇫🇷 · Chengfeng Cai🇨🇳 · Mads T.Frandsen · Martin Rosenlyst🇩🇰 · Hong Hao Zhang🇨🇳

    In a recent letter we proposed a new non-thermal mechanism of Dark Matter production based on vacuum misalignment, where both the Higgs boson and a very light pseudo-scalar $\eta$ emerge from the Dark sector. In this letter, we identify the parameter space in a composite scenario where the light pseudo-scalar can be produced in the sun and explain the XENON1T excess in electron recoil data. The model's Dark Matter candidate has a mass around $50$ TeV and out of range for Direct Detection. Testable predictions include Gravitational waves at frequencies in the Hz range from a cosmological phase transition, an exotic decay $Z\to \gamma +\text{mbox}inv.$ with rates $4÷16\cdot 10^{-12}$ testable at a future Tera-Z collider, and an enhancement by $17÷40$ % of the branching ratio $K_L\to {\pi }^0+\text{mbox}inv.$, not enough to explain the KOTO anomaly. All these predictions may be confirmed by future experiments.

    hep-phPRD(2020)·36 citations
41. 41*

    Beauty baryon non-leptonic decays into decuplet baryons and $CP$-asymmetries based on $SU(3)$-Flavor analysis

    Shibasis Roy🇮🇳 · Rahul Sinha🇮🇳 · N.G.Deshpande🇺🇸

    We consider charmless weak decays of beauty-baryons into decuplet baryons and pseudoscalar mesons in a general framework based on $SU(3)$-flavor decomposition of the decay amplitudes. The dynamical assumption independent $SU(3)$ analysis accounts for the effects of an arbitrarily broken $SU(3)$ symmetry in these decays. An alternative approach in terms of quark diagrams is also provided and compared with the $SU(3)$ decomposition in the limit of exact $SU(3)$-flavor symmetry. Furthermore, the symmetries of the effective Hamiltonian is used to relate or neglect reduced $SU(3)$ amplitudes to derive several sum rule relations between amplitudes and relations between $CP$ asymmetries in these decays and identify those that hold even if $SU(3)$ is broken.

    hep-phPRD(2020)·17 citations
42. 42*

    Initial fluctuations and power spectrum of flow anisotropies in relativistic heavy-ion collisions

    Shreyansh S. Dave🇮🇳 · Saumia P.S.🇷🇺 · Ajit M. Srivastava🇮🇳

    Flow has emerged as a crucial probe for the properties of the thermalized medium produced in relativistic heavy-ion collisions. The evolution of initial state fluctuations leaves imprints on the power spectrum of flow coefficients. Therefore flow coefficients are a crucial probe of initial state fluctuations arising from the parton distributions of the colliding nuclei. This has a very strong correspondence with the physics of power spectrum of cosmic microwave background radiation (CMBR) anisotropies which directly probes initial inflationary fluctuations. Much work has been done to probe these interesting interconnections, in particular, in developing techniques for the measurements of higher flow coefficients. We present a short review of these developments. The effect of initial magnetic field on these features will also be reviewed. All this acquires special importance in view of upcoming electron-ion collider which will directly probe initial parton distribution of the colliding nucleus.

    ↳ nucl-thhep-phnucl-exEur.Phys.J.ST(2021)·2 citations
43. 43*

    Exclusive Diffraction at the LHC

    C. Royon🇺🇸

    In this report, we describe the most recent results on exclusive diffraction from the ATLAS, CMS, LHCb, TOTEM experiments at the LHC concerning exclusive pions, $J/\Psi$, $\Psi (2S)$, dilepton, diphoton, $WW$ productions and prospects concerning the search for anomalous couplings and axion-like particle production.

    ↳ hep-exhep-ph0 citations
44. 44*

    Recent results from the TOTEM collaboration at the LHC

    C. Royon🇺🇸

    We describe the most recent results from the TOTEM collaboration at the LHC, namely the elastic cross section measurements at a center-of-mass on 2.76, 7, 8 and 13 TeV. No structure or resonance is observed at high $t$ at high center-of-mass energies. A pure exponential form of $d\sigma /dt$ is excluded both at 8 and 13 TeV. Accessing the very low $t$ region allows measuring the $\rho$ parameter at 13 TeV.

    ↳ hep-exhep-ph1 citation
45. 45*

    Pulsar radio emission mechanisms: a critique

    D. B. Melrose🇦🇺 · M. Z. Rafat🇦🇺 · A. Mastrano🇦🇺

    We consider critically the three most widely favored pulsar radio emission mechanisms: coherent curvature emission (CCE), beam-driven relativistic plasma emission (RPE) and anomalous Doppler emission (ADE). We assume that the pulsar plasma is one dimensional (1D), streaming outward with a bulk Lorentz factor ${\gamma }_{\mathrm{s}}\gg ⟨\gamma ⟩-1\gtrsim 1$, where $⟨\gamma ⟩$ is the intrinsic spread in the rest frame of the plasma. We argue that the formation of beams in a multi-cloud model is ineffective in the intrinsically relativistic case for plausible parameters, because the overtaking takes too long. We argue that the default choice for the particle distribution in the rest frame is a Jüttner distribution and that relativistic streaming should be included by applying a Lorentz transformation to the rest-frame distribution, rather than the widely assumed relativistically streaming Gaussian distribution. We find that beam-driven wave growth is severely restricted by (a) the wave properties in pulsar plasma, (b) a separation condition between beam and background, and (c) the inhomogeneity of the plasma in the pulsar frame. The growth rate for the kinetic instability is much smaller and the bandwidth of the growing waves is much larger for a Jüttner distribution than for a relativistically streaming Gaussian distribution. No reactive instability occurs at all for a Jüttner distribution. We conclude that none of CCE, RPE and ADE in tenable as the generic pulsar radio emission mechanism for ``plausible'' assumptions about the pulsar plasma.

    ↳ astro-ph.HEhep-phMNRAS(2020)·53 citations
46. 46*

    Precision determination of pion-nucleon coupling constants using effective field theory

    P. Reinert🇩🇪 · H. Krebs🇩🇪 · E. Epelbaum🇩🇪

    The pion-nucleon coupling constants determine the strength of the long-range nuclear forces and play a fundamental part in our understanding of nuclear physics. While the charged- and neutral-pion couplings to protons and neutrons are expected to be very similar, owing to the approximate isospin symmetry of the strong interaction, the different masses of the up- and down-quarks and electromagnetic effects may result in their slightly different values. Despite previous attempts to extract these coupling constants from different systems, our knowledge of their values is still deficient. In this Letter we present a precision determination of these fundamental observables with fully controlled uncertainties from neutron-proton and proton-proton scattering data using chiral effective field theory. To achieve this goal, we use a novel methodology based on the Bayesian approach and perform, for the first time, a full-fledged partial-wave analysis of nucleon-nucleon scattering up to the pion production threshold in the framework of chiral effective field theory, including a complete treatment of isospin-breaking effects and our own determination of mutually consistent data. The resulting values of the pion-nucleon coupling constants are accurate at the percent level and show no significant charge dependence. These results mark an important step towards developing a precision theory of nuclear forces and structure.

    ↳ nucl-thhep-lathep-phnucl-exPRL(2021)·67 citations
47. 47*

    Strong QCD Insights from Excited Nucleon Structure Studies with CLAS and CLAS12

    D.S. Carman🇺🇸 · K. Joo🇺🇸 · V.I. Mokeev🇺🇸

    Studies of the spectrum of hadrons and their structure in experiments with electromagnetic probes offer unique insight into many facets of the strong interaction in the regime of large quark-gluon running coupling, {\it i.e.} the regime of strong QCD. The experimental program within Hall~B at Jefferson Laboratory based on data acquired with the CLAS spectrometer using electron and photon beams with energies up to 6~GeV has already considerably extended the scope of research in hadron physics in joint efforts between experiment and phenomenological data analysis. Impressive progress in relating the hadron structure observables inferred from the data to the strong QCD mechanisms underlying hadron mass generation has been achieved in the past decade. These results will be considerably extended with data from the experimental program with the new CLAS12 spectrometer that has begun data taking using electron beams with energies up to 11~GeV. With this extended kinematic reach the structure of nucleon resonances will be probed at the highest photon virtualities ever achieved in the studies of exclusive electroproduction, which will allow for the exploration of the distance scale where $>$98\% of light hadron mass emerges from QCD in the transition of the strong interaction from the regime of quark-gluon confinement to perturbative QCD.

    ↳ nucl-exhep-phFew Body Syst.(2020)·49 citations
48. 48*

    Dark side of Weyl gravity

    Petr Jizba🇨🇿 · Lesław Rachwał🇨🇿 · Stefano G. Giaccari🇮🇱 · Jaroslav Kňap🇨🇿

    With the help of a functional renormalization group, we study the dynamical breakdown of scale invariance in quantum Weyl gravity by starting from the UV fixed point that we assume to be Gaussian. To this end, we resort to two classes of Bach-flat backgrounds, namely maximally symmetric spacetimes and Ricci-flat backgrounds in the improved one-loop scheme. We show that apart from a genuine IR fixed point that is reached at a zero value of the running scale, the renormalization group flow also exhibits bouncing behavior. We demonstrate that the IR fixed point found is IR-stable in the space of the considered couplings. As a next step, we analyze physics in the broken phase. In particular, we show that in the low-energy sector of the broken phase, the theory looks like Starobinsky $f(R)$ gravity with a gravi-cosmological constant that has a negative sign in comparison to the usual matter-induced cosmological constant. We discuss implications for cosmic inflation and highlight a non-trivial relation between Starobinsky's parameter and the gravi-cosmological constant. Salient issues, including the scheme independence of the IR fixed point and the role of trace anomaly, are also discussed.

    ↳ hep-thgr-qchep-phUniverse(2020)·6 citations
49. 49*

    Extending Standard Atomic Kernel Model with New Interpretation of Strong Forces

    Dr Ing Hongguang Yang · Dr ret nat Weidong Yang

    This paper gives an extended model of the atomic nucleus - we call it the YY model, which allows a new description for strong forces from the well-known Standard Model. The forces that hold the nucleus together (protons and neutrons) can be expressed in a new way. Based on the YY model, more structural description details for an atomic nucleus will be possible than is the case with the conventional description. The YY model is compatible with the standard model. However, it allows for very delicate considerations when modelling the distribution of protons and neutrons within or around an atomic nucleus. Furthermore, it can explain many subatomic processes in an elegant way. The YY model predicts some subatomic aspects that can be explored in a deeper step. Our approach also includes a native common root for the description of macrophysics (space, dark matter and cosmology). Following a model-driven approach - a methodology widely used in computer science and informatics - the investigations in this paper will completely dispense with mathematical formulations. In addition, energy balances in the transformations are left out. Many different aspects that can be derived from this new mechanism can then be verified. We hope to gain the confidence of many other physicists in the YY model. They could make detailed theoretical and experimental verifications by adding additional descriptive elements and linking the YY model to the known quantum field theories and the widely accepted big bang theories for space and cosmology, especially for research on dark matter.

    ↳ nucl-thhep-ph0 citations
50. 50*

    Observable signatures of initial state momentum anisotropies in nuclear collisions

    Giuliano Giacalone🇫🇷 · Bjoern Schenke🇺🇸 · Chun Shen🇺🇸

    We show that the correlation between the elliptic momentum anisotropy, $v_2$, and the average transverse momentum, $[p_T]$, at fixed multiplicity in small system nuclear collisions carries information on the origin of the observed momentum anisotropy. A calculation using a hybrid IP-Glasma+\textsc{Music}+UrQMD model that includes contributions from final state response to the initial geometry as well as initial state momentum anisotropies of the Color Glass Condensate, predicts a characteristic sign change of the correlator $\hat{\rho }(v_2^2,[p_T])$ as a function of charged particle multiplicity in p+Au and d+Au collisions at $\sqrt{s}=200\mathrm{GeV}$, and p+Pb collisions at $\sqrt{s}=5.02\mathrm{TeV}$. This sign change is absent in calculations without initial state momentum anisotropies. The model further predicts a qualitative difference between the centrality dependence of $\hat{\rho }(v_2^2,[p_T])$ in Au+Au collisions at $\sqrt{s}=200\mathrm{GeV}$ and Pb+Pb collisions at $\sqrt{s}=5.02\mathrm{TeV}$, with only the latter showing a sign change in peripheral events. Predictions for O+O collisions at different collision energy show a similar behavior. Experimental observation of these distinct qualitative features of $\hat{\rho }(v_2^2,[p_T])$ in small and large systems would constitute strong evidence for the presence and importance of initial state momentum anisotropies predicted by the Color Glass Condensate effective theory.

    ↳ nucl-thhep-phnucl-exPRL(2020)·72 citations
51. 51*

    Pileup corrections on higher-order cumulants

    Toshihiro Nonaka🇯🇵 · Masakiyo Kitazawa🇯🇵 · ShinIchi Esumi🇯🇵

    We propose a method to remove the contributions of pileup events from higher-order cumulants and moments of event-by-event particle distributions. Assuming that the pileup events are given by the superposition of two independent single-collision events, we show that the true moments in each multiplicity bin can be obtained recursively from lower multiplicity events. In the correction procedure the necessary information are only the probabilities of pileup events. Other terms are extracted from the experimental data. We demonstrate that the true cumulants can be reconstructed successfully by this method in simple models. Systematics on trigger inefficiencies and correction parameters are discussed.

    ↳ physics.data-anhep-phnucl-exnucl-thNucl.Instrum.Meth.A(2020)·18 citations
52. 52*

    Hawking radiation from acoustic black holes in relativistic heavy ion collisions

    Arpan Das🇵🇱 · Shreyansh S. Dave🇮🇳 · Oindrila Ganguly🇮🇳 · Ajit M. Srivastava🇮🇳

    We propose a new analogue model of gravity - the evolving quark gluon plasma (QGP) produced in relativistic heavy ion collisions. This quark gluon plasma is the "most inviscid" fluid known. Such low kinematic viscosity is believed to reflect strongly correlated nature for QGP in these experiments. Hence, it may provide a good example of a quantum fluid naturally suited to studies of acoustic Hawking radiation. Due to rapid longitudinal expansion, presence of a sonic horizon is also naturally guaranteed here, though, in general, this horizon is not static. Using Ultra relativistic quantum molecular dynamics (UrQMD) simulations, we show that, under certain conditions, the longitudinal velocity of the plasma, near the sonic horizon, can become time independent for a short span during the evolution of the system. During this period, we can have a conformally static acoustic metric with a (conformal) Killing horizon coinciding with the apparent horizon. An asymptotic observer will then see a thermal flux of phonons, constituting the Hawking radiation, coming from the horizon. For the relatively low energy collision considered here, where the resulting QCD system is governed by non-relativistic hydrodynamics, we estimate the Hawking temperature to be about 4-5 MeV (with the temperature of the QCD fluid being about 135 MeV). We discuss the experimental signatures of this Hawking radiation in terms of a thermal component in the rapidity dependence of the transverse momentum distribution of detected particles. We also discuss extension to ultra-relativistic case which should lead to a higher Hawking temperature, along with the effects of dynamical horizon leading to blue/red shift of the temperature.

    ↳ gr-qchep-phhep-thnucl-ex+1PLB(2021)·7 citations
53. 53*

    Systematic Analysis of Flow Distributions

    Hadi Mehrabpour🇮🇷

    The information of the event-by-event fluctuations is extracted from flow harmonic distributions and cumulants, which can be done experimentally. In this work, we employ the standard method of Gram-Charlier series with the normal kernel to find such distribution, which is the generalization of recently introduced flow distributions for the studies of the event-by-event fluctuations. Also, we introduce a new set of cumulants $j_n\{2k\}$ which have more information about the fluctuations compared with other known cumulants. The experimental data imply that not only all of the information about the event-by-event fluctuations of collision zone properties and different stages of the heavy-ion process are not encoded in the radial flow distribution $p(v_n)$, but also the observables describing harmonic flows can generally be given by the joint distribution $\mathcal{P}(v_1,v_2,...)$. In such a way, we first introduce a set of joint cumulants ${\mathcal{K}}_{nm}$, and then we find the flow joint distribution using these joint cumulants. Finally, we show that the Symmetric Cumulants $SC(2,3)$ and $SC(2,4)$ obtained from ALICE data are explained by the combinations ${\mathcal{K}}_{22}+\frac{1}{2}{\mathcal{K}}_{04}-{\mathcal{K}}_{31}$ and ${\mathcal{K}}_{22}+4{\mathcal{K}}_{11}^2$.

    ↳ nucl-thhep-phnucl-exPRC(2020)·5 citations
54. 54*

    Out of equilibrium Chiral Vortical Effect in Holography

    Sergio Morales-Tejera🇪🇸 · Karl Landsteiner🇪🇸

    We study the chiral vortical effect far from equilibrium in a strongly coupled holographic field theory. Rotation is represented as a perturbation via a gravito-magnetic field on top of a five-dimensional charged AdS Vaidya metric. We also introduce a momentum relaxation mechanism by linear scalar field backgrounds and study the CVE dynamics as function of the charges, temperature and momentum relaxation. The far from equilibrium behavior shows that the CVE builds up with a significant delay in time compared to the quasi instantaneous equilibration of the background metric. We also pay special attention to the effects of the gravitational contribution to the axial anomaly in the CVE of the axial current. We develop an analytic estimate of this delay and also compute the quasi-normal modes near equilibrium which determine the late time ring down.

    ↳ hep-thhep-phnucl-thPRD(2020)·8 citations
55. 55*

    Machine Learning Etudes in Conformal Field Theories

    Heng-Yu Chen🇹🇼 · Yang-Hui He🇬🇧 · Shailesh Lal🇵🇹 · M. Zaid Zaz🇮🇳

    We demonstrate that various aspects of Conformal Field Theory are amenable to machine learning. Relatively modest feed-forward neural networks are able to distinguish between scale and conformal invariance of a three-point function and identify a crossing-symmetric four-point function to nearly a hundred percent accuracy. Furthermore, neural networks are also able to identify conformal blocks appearing in a putative CFT four-point function and predict the values of the corresponding OPE coefficients. Neural networks also successfully classify primary operators by their quantum numbers under discrete symmetries in the CFT from examining OPE data. We also demonstrate that neural networks are able to learn the available OPE data for scalar correlation function in the 3d Ising model and predict the twists of higher-spin operators that appear in scalar OPE channels by regression.

    ↳ hep-thhep-phInt.J.Data Sci.Math.Sci.(2023)·27 citations
56. 56*

    Nucleon Polarizabilities and Compton Scattering as a Playground for Chiral Perturbation Theory

    Franziska Hagelstein (AEC Bern)🇨🇭

    I give a summary of recent results on nucleon polarizabilities, with emphasis on chiral perturbation theory. The predictive calculations of Compton scattering off the nucleon are compared to recent empirical determinations and lattice QCD calculations of the polarizabilities, thereby testing chiral perturbation theory in the single-baryon sector.

    ↳ nucl-thhep-lathep-phnucl-exSymmetry(2020)·13 citations
57. 57*

    On the photon-pseudoscalar particle mixing in media and external fields

    Damian Ejlli🇬🇧

    In this work, I study the mixing of photons with pseudoscalar particles and vice-versa in the presence of an external magnetic field and a pseudoscalar field. I solve exactly for the first time in the literature the equations of motion of the electromagnetic field coupled with a pseudoscalar field in the presence of a constant magnetic field with arbitrary direction with respect to the direction of propagation of the fields in vacuum. In addition, I also solve exactly the equations of motion in a magnetized plasma/gas for perpendicular propagation with respect to the external magnetic field. By finding exact solutions to the equations of motion, I find exact expressions for the transition efficiencies of photons into pseudoscalar particles in different situations. The expressions of the transition efficiencies generalize and correct those previously found in the literature by using approximate WKB methods on solving the equations of motion. In the case when the direction of propagation of fields with respect to the external magnetic field is not perpendicular, a longitudinal state of the electromagnetic field is generated even in a magnetized vacuum. The appearance of the longitudinal electric field state could be used for laboratory searches of pseudoscalar particles such as the axion and/or axion-like particles.

    ↳ hep-thgr-qchep-phEPJC(2021)·1 citation
58. 58*

    The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe

    Rouzbeh Allahverdi🇺🇸 · Mustafa A. Amin🇺🇸 · Asher Berlin🇺🇸 · Nicolás Bernal🇨🇴 · Christian T. Byrnes🇬🇧 · M. Sten Delos🇺🇸 · Adrienne L. Erickcek🇺🇸 · Miguel Escudero🇬🇧 · Daniel G. Figueroa🇪🇸 · Katherine Freese🇺🇸 · Tomohiro Harada🇯🇵 · Dan Hooper🇺🇸 and 14 other authors

    It is commonly assumed that the energy density of the Universe was dominated by radiation between reheating after inflation and the onset of matter domination 54,000 years later. While the abundance of light elements indicates that the Universe was radiation dominated during Big Bang Nucleosynthesis (BBN), there is scant evidence that the Universe was radiation dominated prior to BBN. It is therefore possible that the cosmological history was more complicated, with deviations from the standard radiation domination during the earliest epochs. Indeed, several interesting proposals regarding various topics such as the generation of dark matter, matter-antimatter asymmetry, gravitational waves, primordial black holes, or microhalos during a nonstandard expansion phase have been recently made. In this paper, we review various possible causes and consequences of deviations from radiation domination in the early Universe - taking place either before or after BBN - and the constraints on them, as they have been discussed in the literature during the recent years.

    ↳ astro-ph.COgr-qchep-phhep-thOpen J.Astrophys.(2021)·345 citations
59. 59*

    Impact of quark deconfinement in neutron star mergers and hybrid star mergers

    Andreas Bauswein🇩🇪 · Sebastian Blacker🇩🇪

    We describe an unambiguous gravitational-wave signature to identify the occurrence of a strong phase transition from hadronic matter to deconfined quark matter in neutron star mergers. Such a phase transition leads to a strong softening of the equation of state and hence to more compact merger remnants compared to purely hadronic models. If a phase transition takes place during merging, this results in a characteristic increase of the dominant postmerger gravitational-wave frequency relative to the tidal deformability characterizing the inspiral phase. By comparing results from different purely hadronic and hybrid models we show that a strong phase transition can be identified from a single, simultaneous measurement of pre- and postmerger gravitational waves. Furthermore, we present new results for hybrid star mergers, which contain quark matter already during the inspiral stage. Also for these systems we find that the postmerger GW frequency is increased compared to purely hadronic models. We thus conclude that also hybrid star mergers with an onset of the hadron-quark phase transition at relatively low densities may lead to the very same characteristic signature of quark deconfinement in the postmerger GW signal as systems undergoing the phase transition during merging.

    ↳ astro-ph.HEhep-phEur.Phys.J.ST(2020)·31 citations
60. 60*

    Exploring straight infinite Wilson lines in the Self Dual and the MHV Lagrangians

    Hiren Kakkad🇵🇱 · Piotr Kotko🇵🇱 · Anna Stasto🇺🇸

    We investigate the appearance of straight infinite Wilson lines lying on the self-dual plane in the context of the Self Dual sector of the Yang Mills theory and in a connection to the Lagrangian implementing the MHV vertices (MHV Lagrangian) according to the Cachazo-Svrcek-Witten method. It was already recognized in the past by two of the authors, that such Wilson line functional provides the field transformation of positive helicity fields between the Yang-Mills theory on the light-cone and the MHV Lagrangian. Here we discuss in detail the connection to the Self Dual sector and we provide a new insight into the solution for the minus helicity field transformation, which can be expressed in terms of a functional derivative of the straight infinite Wilson line on the self-dual plane.

    ↳ hep-thhep-phPRD(2020)·9 citations
61. 61*

    Hadronic light-by-light contribution to $(g-2{)}_{\mu }$ from lattice QCD with SU(3) flavor symmetry

    En-Hung Chao🇩🇪 · Antoine Gérardin🇫🇷 · Jeremy R. Green🇨🇭 · Renwick J. Hudspith🇩🇪 · Harvey B. Meyer🇩🇪

    We perform a lattice QCD calculation of the hadronic light-by-light contribution to $(g-2{)}_{\mu }$ at the SU(3) flavor-symmetric point $m_{\pi }=m_K\simeq 420$MeV. The representation used is based on coordinate-space perturbation theory, with all QED elements of the relevant Feynman diagrams implemented in continuum, infinite Euclidean space. As a consequence, the effect of using finite lattices to evaluate the QCD four-point function of the electromagnetic current is exponentially suppressed. Thanks to the SU(3)-flavor symmetry, only two topologies of diagrams contribute, the fully connected and the leading disconnected. We show the equivalence in the continuum limit of two methods of computing the connected contribution, and introduce a sparse-grid technique for computing the disconnected contribution. Thanks to our previous calculation of the pion transition form factor, we are able to correct for the residual finite-size effects and extend the tail of the integrand. We test our understanding of finite-size effects by using gauge ensembles differing only by their volume. After a continuum extrapolation based on four lattice spacings, we obtain $a_{\mu }^{\mathrm{hlbl}}=(65.4\pm 4.9\pm 6.6)\times 10^{-11}$, where the first error results from the uncertainties on the individual gauge ensembles and the second is the systematic error of the continuum extrapolation. Finally, we estimate how this value will change as the light-quark masses are lowered to their physical values.

    ↳ hep-lathep-phEPJC(2020)·48 citations
62. 62*

    Primordial black holes from cusp collapse on cosmic strings

    Alexander C. Jenkins🇬🇧 · Mairi Sakellariadou🇬🇧

    Primordial black holes (PBHs) are of fundamental interest in cosmology and astrophysics, and have received much attention as a dark matter candidate and as a potential source of gravitational waves. One possible PBH formation mechanism is the gravitational collapse of cosmic strings. Thus far, the entirety of the literature on PBH production from cosmic strings has focused on the collapse of (quasi)circular cosmic string loops, which make up only a tiny fraction of the cosmic loop population. We demonstrate here a novel PBH formation mechanism: the collapse of a small segment of cosmic string in the neighbourhood of a cusp. Using the hoop conjecture, we show that collapse is inevitable whenever a cusp appears on a macroscopically-large loop, forming a PBH whose rest mass is smaller than the mass of the loop by a factor of the dimensionless string tension squared, $(G\mu {)}^2$. Since cusps are generic features of cosmic string loops, and do not rely on finely-tuned loop configurations like circular collapse, this implies that cosmic strings produce PBHs in far greater numbers than has previously been recognised. The resulting PBHs are highly spinning and boosted to ultrarelativistic velocities; they populate a unique region of the BH mass-spin parameter space, and are therefore a "smoking gun" observational signature of cosmic strings. We derive new constraints on $G\mu$ from the evaporation of cusp-collapse PBHs, and update existing constraints on $G\mu$ from gravitational-wave searches.

    ↳ astro-ph.COgr-qchep-ph55 citations
63. 63*

    The Standard Model, The Exceptional Jordan Algebra, and Triality

    Latham Boyle🇨🇦

    Jordan, Wigner and von Neumann classified the possible algebras of quantum mechanical observables, and found they fell into 4 "ordinary" families, plus one remarkable outlier: the exceptional Jordan algebra. We point out an intriguing relationship between the complexification of this algebra and the standard model of particle physics, its minimal left-right-symmetric $SU(3)\times SU(2{)}_L\times SU(2{)}_R\times U(1)$ extension, and $Spin(10)$ unification. This suggests a geometric interpretation, where a single generation of standard model fermions is described by the tangent space $(\mathbb{C}\otimes \mathbb{O}{)}^2$ of the complex octonionic projective plane, and the existence of three generations is related to $SO(8)$ triality.

    ↳ hep-thhep-phquant-phJ.Math.Phys.(2026)·48 citations
64. 64*

    PPS results and prospects from CMS/TOTEM collaborations

    C. Royon🇺🇸

    We describe the most recent results from the Proton Precision Spectrometer from the CMS and TOTEM collaborations, namely the first observation of exclusive di-lepton production at high mass at the LHC, and the prospects concerning the sensitivity to quartic anomalous couplings..

    ↳ hep-exhep-ph0 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.