Tue·May 24, 2022Tuesday·May 24, 2022

1. 01*

   Distinguishing (Dirac or Majorana) neutrinos in purely leptonic decays of leptons

   Yao Yu🇨🇳 · Bai-Cian Ke🇨🇳

   We investigate purely leptonic decays of leptons ${\text{l}}^{\prime -}\to l^{-}{\bar{\nu }}_l{\nu }_{l^{\prime }}$ to distinguish Dirac or Majorana neutrinos. We derive the differences of the decay width (and associated quantities) between the two neutrino hypotheses by the effect of identical particles. Evidence from experimental data makes the hypothesis of Majorana neutrinos very unlikely and our results strongly favor the hypothesis of Dirac neutrinos (in the standard three-neutrino theory). Moreover, our exploration for decay widths can be extended to the polarization angles of leptons, which will inspire new information for experimental and theoretical studies.

   hep-phhep-exhep-thnucl-th0 citations
2. 02*

   Lepton flavor violation within the Simplest Little Higgs model

   Enrique Ramirez🇲🇽 · Pablo Roig🇲🇽

   We carry out an exhaustive analysis of lepton flavor violating processes within the Simplest Little Higgs model. Its discovery could be expected from either $\mu \to e$ conversion in nuclei, $\mu \to e\gamma$ or $\mu \to 3e$ decays. Then, the tau sector could help discriminating this model not only via $\tau \to \ell \gamma$ ($\ell =\mu ,e$) and $\tau \to 3\ell$ decays, but also by means of $\ell \to \tau$ conversion in nuclei, which is promising in this respect. Although the model violates slightly custodial symmetry, acommodating the recent CDF $M_W$ measurement is in tension with electroweak precision data.

   hep-phhep-exPRD(2022)·13 citations
3. 03*

   Parton distributions need representative sampling

   Aurore Courtoy🇲🇽 · Joey Huston🇺🇸 · Pavel Nadolsky🇺🇸 · Keping Xie🇺🇸 · Mengshi Yan🇨🇳 · C.-P. Yuan🇺🇸

   In global QCD fits of parton distribution functions (PDFs), a large part of the estimated uncertainty on the PDFs originates from the choices of parametric functional forms and fitting methodology. We argue that these types of uncertainties can be underestimated with common PDF ensembles in high-stake measurements at the Large Hadron Collider and Tevatron. A fruitful approach to quantify these uncertainties is to view them as arising from sampling of allowed PDF solutions in a multidimensional parametric space. This approach applies powerful insights gained in recent statistical studies of large-scale population surveys and quasi-Monte Carlo integration methods. In particular, PDF fits may be affected by the big data paradox, which stipulates that more experimental data do not automatically raise the accuracy of PDFs -- close attention to the data quality and sampling of possible PDF solutions is as essential. To test if the sampling of the PDF uncertainty of an experimental observable is truly representative of all acceptable solutions, we introduce a technique (``a hopscotch scan'') based on a combination of parameter scans and stochastic sampling. With this technique, we show that the PDF uncertainty on key LHC cross sections at 13 TeV obtained with the public NNPDF4.0 fitting code is larger than the nominal uncertainty obtained with the published NNPDF4.0 Monte-Carlo replica sets, when accounting for the likelihood distribution. On the same grounds, the uncertainties on the charm distribution at a large momentum fraction $x$ and gluon PDF at small $x$ are enlarged. In PDF ensembles obtained in the analytic minimization (Hessian) formalism, the tolerance on the PDF uncertainty must be based on sufficiently complete sampling of PDF functional forms and choices of the experiments.

   hep-phPRD(2023)·42 citations
4. 04*

   $W$ mass in a model with vector-like leptons and $U(1{)}^{\prime }$

   Junichiro Kawamura🇰🇷 · Stuart Raby🇺🇸

   We study the effects of vector-like leptons on the $W$ boson mass in a model with a vector-like $U(1{)}^{\prime }$ gauge symmetry. This model provides simultaneous explanations for the recent anomalies in the muon anomalous magnetic moment and the semi-leptonic decays of $B$ mesons. We found that the recent result of the $W$ boson mass precise measurement at CDF can be explained if the charged (neutral) vector-like lepton is lighter than 250 (80) GeV. The light vector-like leptons may not be excluded by collider experiments if these decay to a physical mode of the $U(1{)}^{\prime }$ breaking scalar field.

   hep-phhep-exPRD(2022)·24 citations
5. 05*

   Lepton flavor violating decays $l_j\to l_i\gamma$ in the $U(1{)}_X$SSM model within the Mass Insertion Approximation

   Tong-Tong Wang🇨🇳 · Shu-Min Zhao🇨🇳 · Jian-Fei Zhang🇨🇳 · Xing-Xing Dong🇨🇳 · Tai-Fu Feng🇨🇳

   Three singlet new Higgs superfields and right-handed neutrinos are added to MSSM to obtain $U(1{)}_X$SSM model. Its local gauge group is $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y\times U(1{)}_X$. In the framework of $U(1{)}_X$SSM, we study muon anomalous magnetic moment and lepton flavor violating decays $l_j\to l_i\gamma (j=2,3;i=1,2)$ within the Mass Insertion Approximation(MIA). Through the MIA method, we can find the parameters that directly affect the analytical result of the lepton flavor violating decays $l_j\to l_i\gamma$, which make our work more convenient. We want to provide a set of simple analytic formulas for the form factors and the associated effective vertices, that may be very useful for future phenomenological studies of the lepton flavor violating decays. According to the accuracy of the numerical results which the influence of different sensitive parameters, we come to the conclusion that the non-diagonal elements which correspond to the generations of the initial lepton and final lepton are main sensitive parameters and lepton flavor violation(LFV) sources. This work can provide a clear signal of new physics(NP).

   hep-phEPJC(2022)·6 citations
6. 06*

   Charged Lepton Flavour Violation in Heavy Particle DEcays

   Wolfgang Altmannshofer🇺🇸 · Cecile Caillol🇨🇭 · Mogens Dam🇩🇰 · Stefania Xella🇩🇰 · Yongchao Zhang🇨🇳

   Charged lepton flavor violation is an unambiguous signature for New Physics. Here we present a summary of the theoretical and experimental status of the search for charged lepton flavor violation in heavy particle decays, in particular in the decays of the Z and Higgs bosons, and of the top quark. Decays of beyond-Standard-Model particles such as a Z' or an additional scalar particle are also discussed. Finally the prospects for such searches at proposed future electron-positron colliders are reviewed.

   hep-ph18 citations
7. 07*

   Interface effects of quark matter: Light-quark nuggets and compact stars

   Cheng-Jun Xia🇨🇳 · Jian-Feng Xu🇨🇳 · Guang-Xiong Peng🇨🇳 · Ren-Xin Xu🇨🇳

   The interface effects of quark matter play important roles in the properties of compact stars and small nuggets such as strangelets and $ud$QM nuggets. By introducing a density derivative term to the Lagrangian density and adopting Thomas-Fermi approximation, we find it is possible to reproduce the results obtained by solving Dirac equations. Adopting certain parameter sets, the energy per baryon of $ud$QM nuggets decreases with baryon number $A$ and become more stable than nuclei at $A\gtrsim 300$. The effects of quark matter symmetry energy are examined, where $ud$QM nuggets at $A\approx 1000$ can be more stable than others if large symmetry energy is adopted. In such cases, larger $ud$QM nuggets will decay via fission and the surface of an $ud$QM star will fragment into a crust made of $ud$QM nuggets and electrons, which resembles the cases of a strange star's crust. The corresponding microscopic structures are then investigated adopting spherical and cylindrical approximations for the Wigner-Seitz cells, where the droplet phase is found to be the most stable configuration with $ud$QM stars' crusts and $ud$QM dwarfs made of $ud$QM nuggets ($A\approx 1000$) and electrons. For the cases considered here, the crust thickness of $ud$QM stars is typically $\sim$200 m, which reaches a few kilometers if we neglect the interface effects and adopt Gibbs construction. The masses and radii of $ud$QM dwarfs are smaller than typical white dwarfs, which would increase if the interface effects are neglected.

   hep-phastro-ph.HEPRD(2022)·19 citations
8. 08*

   Dark Stars Powered by Self-Interacting Dark Matter

   Youjia Wu🇺🇸 · Sebastian Baum🇺🇸 · Katherine Freese🇺🇸 · Luca Visinelli🇨🇳 · Hai-Bo Yu🇺🇸

   Dark matter annihilation might power the first luminous stars in the Universe. These types of stars, known as dark stars, could form in $(10^6-10^8)M_{\odot }$ protohalos at redshifts $z\sim 20$, and they could be much more luminous and larger in size than ordinary stars powered by nuclear fusion. We investigate the formation of dark stars in the self-interacting dark matter (SIDM) scenario. We present a concrete particle physics model of SIDM that can simultaneously give rise to the observed dark matter density, satisfy constraints from astrophysical and terrestrial searches, and address the various small-scale problems of collisionless dark matter via the self-interactions. In this model, the power from dark matter annihilation is deposited in the baryonic gas in environments where dark stars could form. We further study the evolution of SIDM density profiles in the protohalos at $z\sim 20$. As the baryon cloud collapses due to the various cooling processes, the deepening gravitational potential can speed up gravothermal evolution of the SIDM halo, yielding sufficiently high dark matter densities for dark stars to form. We find that SIDM-powered dark stars can have similar properties, such as their luminosity and size, as dark stars predicted in collisionless dark matter models.

   hep-phastro-ph.COPRD(2022)·23 citations
9. 09*

   Is the decay of the Higgs boson to a photon and a dark photon currently observable at the LHC?

   Hugues Beauchesne🇹🇼 · Cheng-Wei Chiang🇹🇼

   Many attempts have been made to observe the decay of the Higgs boson to a photon and an invisible massless dark photon. For this decay to be potentially observable at the LHC, new mediators that communicate between the Standard Model and the dark photon must exist. In this Letter, we study bounds on such mediators coming from the Higgs signal strengths, oblique parameters, electric dipole moment of the electron and unitarity. We find that the branching ratio of the Higgs boson to a photon and a dark photon is constrained to be far smaller than the sensitivity of current collider searches, thus calling for a reconsideration of current experimental efforts.

   hep-phhep-exPRL(2023)·7 citations
10. 10*

    Prediction of a narrow exotic hadronic state with quantum numbers $J^{PC}=0^{--}$

    Teng Ji🇨🇳 · Xiang-Kun Dong🇨🇳 · Feng-Kun Guo🇨🇳 · Bing-Song Zou🇨🇳

    Lots of charmonium-like structures have been observed in the last two decades. Most of them have quantum numbers that can be formed by a pair of charm and anticharm quarks, thus it is difficult to unambiguously identify the exotic ones among them. In this Letter, by exploiting heavy quark spin symmetry, we present a robust prediction of the hadronic molecular scenario, where the $\psi (4230),\psi (4360)$ and $\psi (4415)$ are identified as $D{\bar{D}}_1,D^{\ast }{\bar{D}}_1$ and $D^{\ast }{\bar{D}}_2^{\ast }$ bound states, respectively. We show that a flavor-neutral charmonium-like exotic state with quantum numbers $J^{PC}=0^{--}$, denoted as ${\psi }_0(4360)$, should exist as a $D^{\ast }{\bar{D}}_1$ bound state. The mass and width of the ${\psi }_0(4360)$} are predicted to be $(4366\pm 18)$ MeV and less than 10 MeV, respectively. The ${\psi }_0(4360)$ is significant in two folds: no $0^{--}$ hadron has been observed so far, and a study of this state will enlighten the understanding of the mysterious vector mesons between 4.2 and 4.5 GeV, as well as the nature of previously observed exotic $Z_c$ and $P_c$ states. We propose that such an exotic state can be searched for in $e^{+}{e}^{-}\to \eta {\psi }_0(4360)$ and uniquely identified by measuring the angular distribution of the outgoing $\eta$ meson.

    hep-phhep-exhep-latPRL(2022)·43 citations
11. 11*

    Constraining the Active-to-Heavy-Neutrino transitional magnetic moments associated with the $Z^{\prime }$ interactions at FASER$\nu$

    Kingman Cheung🇹🇼 · C.J. Ouseph🇹🇼

    We investigate the effects of the transitional magnetic dipole moment of the active-to-heavy-neutrino associated with a new neutral gauge boson $Z^{\prime }$ on neutrino-nucleon scattering at the ForwArd Search ExpeRiment-$\nu$ (FASER$\nu$). We consider the neutral-current neutrino-nucleon scattering ($\nu A\to NA$) as the production mechanism of the heavy neutrino $N$ at FASER$\nu$ and estimate the sensitivity reach on the magnetic moment coupling ${\mu }_{{\nu }_{\alpha }}$ for a range of heavy neutrino mass ($1\mathrm{GeV}<M_N<70\mathrm{GeV}$). In this study, we consider three benchmark models, in which the heavy neutrino is coupled to $L_e$, $L_{\mu }$ or $L_{\tau }$ doublet, respectively.

    hep-phhep-exEPJC(2023)·7 citations
12. 12*

    The $Z_{cs}$ states and the mixture of hadronic molecule and diquark-anti-diquark components within effective field theory

    Ze-Hua Cao🇨🇳 · Wei He🇨🇳 · Zhi-Feng Sun🇨🇳

    In this work, we construct the Lagrangian describing meson-diquark interaction, such that the diquark-anti-diquark component as well as the molecular component is introduced when studying the $Z_{cs}$ states. In this way, the problem is solved that if only considering the ${\bar{D}}^{(\ast )}{D}_s^{(\ast )}$ components, the potentials are suppressed by OZI rule. Through solving the Bethe-Salpeter equation, we find that the $Z_{cs}(4000{)}^{+}$ can be explained as the mixture of ${\bar{D}}^{\ast 0}{D}_s^{+}$ and ${\bar{A}}_{cs}{S}_{cu}$ components. Besides, for the ${\bar{D}}^{\ast 0}{D}_s^{\ast +}/{\bar{A}}_{cs}{A}_{cu}$ system, the pole of $4208\pm 13i$ MeV on the second Riemann sheet is predicted, whose mass agrees with that of $Z_{cs}(4220{)}^{+}$ while the width is much smaller than $Z_{cs}(4220{)}^{+}$. Due to the large error of the $Z_{cs}(4220{)}^{+}$'s width, further measurements are expected. In addition, several other poles of different spins are predicted.

    hep-phPRD(2023)·7 citations
13. 13*

    Strangeness enhancement across collision systems without a plasma

    Christian Bierlich🇸🇪 · Smita Chakraborty🇸🇪 · Gösta Gustafson🇸🇪 · Leif Lönnblad🇸🇪

    We present novel rope hadronization results for strange hadron enhancement in pp, pPb, and PbPb collisions using PYTHIA/Angantyr at LHC energies. With the rope model for string fragmentation, we find that the strangeness and baryon enhancement has a coherent increase across all collision systems as a function of average charged central multiplicity, in qualitative agreement with LHC data. In AA collisions, we find that the baryonic yields overshoot data at high multiplicities, and we discuss how a combination of rope hadronization with other string interactions may tame this rise.

    hep-phnucl-thPLB(2022)·25 citations
14. 14*

    Transverse Mass Distribution and Charge Asymmetry in W Boson Production to Third Order in QCD

    Xuan Chen🇩🇪 · Thomas Gehrmann🇨🇭 · Nigel Glover🇬🇧 · Alexander Huss🇨🇭 · Tong-Zhi Yang🇨🇭 · Hua Xing Zhu🇨🇳

    Charged gauge boson production at hadron colliders is a fundamental benchmark for the extraction of electroweak parameters and the understanding of the proton structure. To enable precision phenomenology for this process, we compute the third-order (N${}^3$LO) QCD corrections to the rapidity distribution and charge asymmetry in W boson production and to the transverse mass distribution of its decay products. Our results display substantial QCD corrections in kinematic regions relevant for Tevatron and LHC measurements. We compare the numerical magnitude of the N${}^3$LO corrections with uncertainties from electroweak input parameters and quantify their potential impact on the determination of the W boson mass.

    hep-phhep-exPLB(2023)·62 citations
15. 15*

    Pion damping width and pion spectral function in hot pion gas

    D. Goderidze🇷🇺 · A. Friesen🇷🇺 · Yu. Kalinovsky🇷🇺

    The temperature behaviour of the pion width in the hadronic phase is investigated in the framework of the NJL model. The contribution to the width from the pion-pion collision is considered with a scalar sigma-meson as an intermediate state. It is shown that the pion width significantly broadens at $T>0.1$ GeV. Using the two-step iteration method, suggested by Kadanoff and Baym, the pion spectral function in a hot pion gas is calculated at different temperatures.

    hep-phnucl-thInt.J.Mod.Phys.A(2022)·3 citations
16. 16*

    New description of neutrino flavour evolution in solar matter

    Jakub Rembielinski🇵🇱 · Jacek Ciborowski🇵🇱

    Assuming that the interacting neutrino and the solar matter can be treated as an open quantum system we formulate a formalism of neutrino state evolution in terms of the Bloch vector, obtained by solving a quasilinear extension of the von Neumann equation. We broaden the classical Wolfenstein formalism by means of exploiting the strictly linear von Neumann equation and reinterpreting the results in terms of the quantities appropriate for the quasilinear approach. We obtain similar predictions for the averaged neutrino survival probability measured on Earth in both approaches, differing by details inside the Sun where the quasilinear evolution predicts a suppression of oscillations. We discuss the issues of energy transfer between the neutrino and the Sun and the speed of the state evolution in both approaches.

    hep-phhep-th0 citations
17. 17*

    Superradiant Production of Heavy Dark Matter from Primordial Black Holes

    Nicolás Bernal🇨🇴 · Yuber F. Perez-Gonzalez🇬🇧 · Yong Xu🇩🇪

    Rotating black holes (BHs) can efficiently transfer energy to the surrounding environment via superradiance. In particular, when the Compton length of a particle is comparable to the gravitational radius of a BH, the particle's occupation number can be exponentially amplified. In this work, we investigate the effect of the primordial-black-hole (PBH) superradiant instabilities on the generation of heavy bosonic dark matter (DM) with mass above $\sim$ 1 TeV. Additionally, we analyze its interplay with other purely gravitational and therefore unavoidable DM production mechanisms such as Hawking emission and the ultraviolet freeze-in. We find that superradiance can significantly increase the DM density produced by PBHs with respect to the case that only considers Hawking emission, and hence lower initial PBH densities are required.

    hep-phastro-ph.COPRD(2022)·61 citations
18. 18*

    Dark Solar Wind

    Jae Hyeok Chang🇺🇸 · David E. Kaplan🇺🇸 · Surjeet Rajendran🇺🇸 · Harikrishnan Ramani🇺🇸 · Erwin H. Tanin🇺🇸

    We study the solar emission of light dark sector particles that self-interact strongly enough to self-thermalize. The resulting outflow behaves like a fluid which accelerates under its own thermal pressure to highly relativistic bulk velocities in the solar system. Compared to the ordinary non-interacting scenario, the local outflow has at least $\sim 10^3$ higher number density and correspondingly at least $\sim 10^3$ lower average energy per particle. We show how this generic phenomenon arises in a dark sector comprised of millicharged particles strongly self-interacting via a dark photon. The millicharged plasma wind emerging in this model has novel yet predictive signatures that encourages new experimental directions. This phenomenon demonstrates how a small step away from the simplest models can lead to radically different outcomes and thus motivates a broader search for dark sector particles.

    hep-phastro-ph.SRhep-exPRL(2022)·20 citations
19. 19*

    Classification of Abelian domain walls

    Yongcheng Wu🇨🇳 · Ke-Pan Xie🇺🇸 · Ye-Ling Zhou🇨🇳

    We discuss domain walls from spontaneous breaking of Abelian discrete symmetries $Z_N$. A series of different domain wall structures are predicted, depending on the symmetry and charge assignments of scalars leading to the spontaneous symmetry breaking (SSB). A widely-existing type of domain walls are those separating degenerate vacua which are adjacent in the field space. We denote these walls as adjacency walls. In the case that $Z_N$ terms are small compared with the $U(1)$ terms, the SSB of $U(1)$ generates strings first and then adjacency walls bounded by strings are generated after the SSB of $Z_N$. For symmetries larger than $Z_3$, non-adjacent vacua exist, we regard walls separating them as non-adjacency walls. These walls are unstable if $U(1)$ is a good approximation. If the discrete symmetry is broken via multiple steps, we arrive at a complex structure that one kind of walls wrapped by another type. On the other hand, if the symmetry is broken in different directions independently, walls generated from the different breaking chains are blind to each other.

    hep-phastro-ph.COhep-thPRD(2022)·28 citations
20. 20*

    Implications of the Zero 1-3 Flavour Mixing Hypothesis: Predictions for ${\theta }_{23}^{\mathrm{PMNS}}$ and ${\delta }^{\mathrm{PMNS}}$

    Stefan Antusch🇨🇭 · Kevin Hinze🇨🇭 · Shaikh Saad🇨🇭

    We revisit mixing sum rule relations in the lepton and quark sectors under the assumption that the 1-3 elements of the flavour mixing matrices ($V_L^u,V_L^d,V_L^e,V_L^{\nu }$) are zero in the flavour basis. We consider the exact relations resulting from the validity of this "zero 1-3 flavour mixing hypothesis" and analyse their implications based on the current experimental data, including effects from RG running. In particular, we analyse how the existing precise measurement of ${\theta }_{13}^{\mathrm{PMNS}}$ allows to derive predictions for ${\theta }_{23}^{\mathrm{PMNS}}$ in models with constrained ${\theta }_{12}^{\mathrm{e}}$. As examples, we calculate the predictions for ${\theta }_{23}^{\mathrm{PMNS}}$ which arise in classes of Pati-Salam models and SU(5) GUTs that relate ${\theta }_{12}^{\mathrm{e}}$ to ${\theta }_{12}^{\mathrm{d}}$. We also derive a novel "lepton phase sum rule", valid under the additional assumption of small charged lepton mixing contributions. We furthermore point out that, in the context of GUT flavour models, the quark and lepton CP violating phases ${\delta }^{\mathrm{CKM}}$ and ${\delta }^{\mathrm{PMNS}}$ can both be predicted from a single imaginary element in the mass matrices.

    hep-phJHEP(2022)·5 citations
21. 21*

    Improved indirect limits on charm and bottom quark EDMs

    Yohei Ema🇺🇸 · Ting Gao🇺🇸 · Maxim Pospelov🇺🇸

    We derive indirect limits on the charm and bottom quark electric dipole moments (EDMs) from paramagnetic AMO and neutron EDM experiments. The charm and bottom quark EDMs generate $CP$-odd photon-gluon operators and light quark EDMs at the $c$- and $b$-quark mass thresholds. These $CP$-odd operators induce the $CP$-odd semi-leptonic operator $C_S$ and the neutron EDM below the QCD scale that are probed by the paramagnetic and neutron EDM experiments, respectively. The bound from $C_S$ is $|d_c|<1.3\times 10^{-20}e\mathrm{cm}$ for the charm quark and $|d_b|<7.6\times 10^{-19}e\mathrm{cm}$ for the bottom quark, with its uncertainty estimated as 10%. The neutron EDM provides a stronger bound, $|d_c|<6\times 10^{-22}e\mathrm{cm}$ and $|d_b|<2\times 10^{-20}e\mathrm{cm}$, though with a larger hadronic uncertainty.

    hep-phhep-exnucl-thJHEP(2022)·16 citations
22. 22*

    Dark Radiation Constraints on Heavy QCD Axions

    David I. Dunsky🇺🇸 · Lawrence J. Hall🇺🇸 · Keisuke Harigaya🇨🇭

    The naturalness problem of PQ symmetry motivates study of the heavy QCD axion, with masses $m_a>$ 1 MeV generated at scales above the QCD scale, and low values of the PQ symmetry breaking scale, $f_a$. We compute the abundance of such axions in a model-independent way, assuming only that they freeze-out after reheating from inflation, and are not subsequently diluted by new physics. If these axions decay between neutrino decoupling and the last scatter era of the Cosmic Microwave Background (CMB), they dilute the neutrinos and their abundance is constrained by CMB measurements of the energy density in dark radiation, $N_{\mathrm{eff}}$. We accurately compute this bound using a numerical code to evolve the axion momentum distribution, including many key processes and effects previously ignored. We assume that the only relevant axion decays are to final states involving Standard Model particles. We determine regions of $(m_a,f_a)$ that will give a signal in $N_{\mathrm{eff}}$ at CMB Stage 4 experiments. We similarly compute the $N_{\mathrm{eff}}$ bound and CMB Stage 4 signal for heavy axions that can decay to light mirror photons. Finally, we compute the bounds on heavy axions with mass below 1 MeV that decay after the era of CMB last scatter, from their contribution to cold or hot dark matter or $N_{\mathrm{eff}}$ at this era.

    hep-phJHEP(2024)·19 citations
23. 23*

    Kinetic Mixing from Kaluza-Klein Modes: A Simple Construction for Portal Matter

    George N. Wojcik🇺🇸

    The vector portal/kinetic mixing simplified model of dark matter, in which thermal dark matter of a mass ranging from a few MeV to a few GeV can be realized with a dark-sector $U(1)$, relies on a small kinetic mixing term between this dark $U(1)$ and the Standard Model (SM) hypercharge. It is well-known that kinetic mixing of the right magnitude can be generated at one loop by the inclusion of "portal matter" fields which are charged under both the dark $U(1)$ and the SM hypercharge, and it has been previously argued on phenomenological grounds that fermionic portal matter fields must exhibit a specific set of characteristics: They must be vector-like and have the same Standard Model group representations as existing SM fermions. A natural explanation for the presence of dark $U(1)$-charged copies of SM fermions would be to enlarge the dark gauge group and embed the SM and the portal matter into a single dark multiplet, however, previous works in this direction require significant ad hoc additions to ensure that the portal matter fields are vector-like while the SM fields are chiral, and rely on complicated dark Higgs sectors to realize the appropriate symmetry breaking. In this paper, we argue that a model with large extra dimensions can easily generate chiral SM fermions and vector-like portal matter from a single dark bulk multiplet, while allowing for a far simpler dark Higgs sector. We present a minimal construction of this "Kaluza-Klein (KK) portal matter" and explore its phenomenology at the LHC, noting that even our simple realization exhibits signatures unique from those of more conventional models with large extra dimensions and 4-D portal matter. Generically, the portal matter sector fields will be much lighter than the other KK fields in the model, so the portal matter sector has the potential to be the first observable experimental signature of an extra dimension.

    hep-phPRD(2023)·20 citations
24. 24*

    Prospects for Heavy WIMP Dark Matter Searches at Muon Colliders

    Kevin Black🇺🇸 · Tulika Bose🇺🇸 · Yuze Chen🇺🇸 · Sridhara Dasu🇺🇸 · Haoyi Jia🇺🇸 · Deborah Pinna🇺🇸 · Varun Sharma🇺🇸 · Nikhilesh Venkatasubramanian🇺🇸 · Carl Vuosalo🇺🇸

    Plots summarizing the constraints on Dark Matter models can help visualize synergies between different searches for the same kind of experiment, as well as between different experiments. In this whitepaper, we present an update to the European Strategy Briefing Book plots, from the perspective of collider searches within the Dark Matter at the Energy Frontier (EF10) Snowmass Topical Group, starting from inputs from future collider facilities. We take as a starting point the plots currently made for LHC searches using benchmark models recommended by the Dark Matter Working Group, also used for the BSM and Dark Matter chapters of the European Strategy Briefing Book. These plots can also serve as a starting point for cross-frontier discussions about dark matter complementarity, and could be updated as a consequence of these discussions. This is a whitepaper submitted to the APS Snowmass process for the EF10 topical group.

    ↳ hep-exhep-ph19 citations
25. 25*

    Chiral gravitational waves from thermalized neutrinos in the early Universe

    Philipp Gubler🇯🇵 · Naoki Yamamoto🇯🇵 · Di-Lun Yang🇹🇼

    We investigate polarized gravitational waves generated by chiral fermions in the early Universe. In particular, we focus on the contribution from left-handed neutrinos in thermal equilibrium with finite temperature and chemical potential in the radiation dominated era. We compute the correlation functions of gravitational fields pertinent to the Stokes parameter $V$ characterizing the circular polarization of gravitational waves in the Minkowski and expanding spacetime backgrounds. In the expanding universe, we find that the thermalized neutrinos induce a non-vanishing $V$ linear to the neutrino degeneracy parameter and wavenumber of gravitational waves in the long wavelength region. While the magnitude of the gravitational waves generated by thermal neutrinos is too small to be detectable by current and planned third generation gravitational wave detectors, their observations by future generation detectors for ultra-high frequency regimes could provide information on the neutrino degeneracy parameter in the early Universe.

    ↳ astro-ph.COgr-qchep-phJCAP(2022)·3 citations
26. 26*

    Termination of Superradiance from a Binary Companion

    Xi Tong🇨🇳 · Yi Wang🇨🇳 · Hui-Yu Zhu🇨🇳

    We study the impact of a binary companion on black hole superradiance at orbital frequencies away from the gravitational-collider-physics (GCP) resonance bands. A superradiant state can couple to a strongly absorptive state via the tidal perturbation of the companion, thereby acquiring a suppressed superradiance rate. Below a critical binary separation, this superradiance rate becomes negative, and the boson cloud gets absorbed by the black hole. This critical binary separation leads to tight constraints on GCP. Especially, a companion with mass ratio $q>10^{-3}$ invalidates all GCP fine structure transitions, as well as almost all Bohr transitions except those from the $|{\psi }_{211}⟩$ state. Meanwhile, the backreaction on the companion manifests itself as a torque acting on the binary, producing floating/sinking orbits that can be verified via pulsar timing. In addition, the possible termination of cloud growth may help to alleviate the current bounds on the ultralight boson mass from various null detections.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRD(2022)·57 citations
27. 27*

    Attractive $N$-$\varphi$ Interaction and Two-Pion Tail from Lattice QCD near Physical Point

    Yan Lyu🇨🇳 · Takumi Doi🇯🇵 · Tetsuo Hatsuda🇯🇵 · Yoichi Ikeda🇯🇵 · Jie Meng🇨🇳 · Kenji Sasaki🇯🇵 · Takuya Sugiura🇯🇵

    First results on the interaction between the $\varphi$-meson and the nucleon ($N$) are presented based on the ($2+1$)-flavor lattice QCD simulations with nearly physical quark masses. Using the HAL QCD method, the spacetime correlation of the $N$-$\varphi$ system in the spin 3/2 channel is converted into the $N$-$\varphi$ scattering phase shift through the interaction potential. The $N$-$\varphi$ potential appears to be a combination of a short-range attractive core and a long-range attractive tail. The latter is found to be consistent with the two-pion exchange (TPE) obtained from the interaction between a color-dipole and the nucleon. The resultant scattering length and effective range for $m_{\pi }=$ 146.4 MeV are $a_0^{(3/2)}=-1.43(23{)}_{stat.}{\left({}_{-06}^{+36}\right)}_{syst.}\mathrm{fm}$ and $r_{\mathrm{eff}}^{(3/2)}=2.36(10{)}_{stat.}{\left({}_{-48}^{+02}\right)}_{syst.}\mathrm{fm}$, respectively. The magnitude of the scattering length is shown to have nontrivial dependence of $m_{\pi }$ and is sensitive to the existence of the long-range tail from TPE.

    ↳ hep-lathep-exhep-phnucl-ex+1PRD(2022)·73 citations
28. 28*

    Prospect for measurement of the CP-violating phase ${\varphi }_s$ in the $B_s\to J/\psi \varphi$ channel at a future Z factory

    Xiaomei Li🇨🇳 · Manqi Ruan🇨🇳 · Mingrui Zhao🇨🇳

    The CP-violating phase ${\varphi }_s$, the \Bs decay width (${\Gamma }_s$), and the \Bs decay width difference ($\Delta {\Gamma }_s$) are sensitive probes to new physics and can constrain the heavy quark expansion theory. The potential for the measurement at future $Z$ factories is studied in this manuscript. It is found that operating at Tera-$Z$ mode, the expected precision can reach: $\sigma ({\varphi }_s)=4.6\mathrm{mrad}$, $\sigma (\Delta {\Gamma }_s)=2.4\mathrm{n}{\mathrm{s}}^{-1}$ and $\sigma ({\Gamma }_s)=0.72\mathrm{n}{\mathrm{s}}^{-1}$. The precision of ${\varphi }_s$ is 40\% larger than the expected precision with the LHCb experiment at HL-LHC. If operating at 10-Tera-$Z$ mode, the precision of ${\varphi }_s$ can be measured at 45\% of the precision obtained from the LHCb experiment at HL-LHC. However, the measurement of ${\Gamma }_s$ and $\Delta {\Gamma }_s$ cannot benefit from the excellent time resolution and tagging power of the future $Z$-factories. Only operating at 10-Tera-$Z$ mode can the ${\Gamma }_s$ and $\Delta {\Gamma }_s$ reach an 18\% larger precision than the precision expected to be obtained from LHCb at HL-LHC. The control of penguin contamination at the future Z-factories is also discussed.

    ↳ hep-exhep-phEPJC(2024)·13 citations
29. 29*

    Computational needs of quantum mechanical calculations of materials for high-energy physics

    Sinéad M. Griffin🇺🇸

    Searches for new physics in high-energy physics (HEP) experiments commonly rely on interactions with materials. A burgeoning direction is the accurate calculation and design of materials for HEP applications. In this Snowmass contribution, I briefly motivate the science need for quantum mechanical calculations of materials for HEP and outline the range of questions that such calculations can address. With this information, I assess the computational needs for ab initio calculations in HEP, the specific computational resources and workflows used by state-of-the-art methods, and finally identify promising future directions such as the use of machine learning and strongly-correlated quantum mechanical calculations moving towards materials calculations on quantum computers.

    ↳ hep-exhep-ph1 citation
30. 30*

    Spinodal Enhancement of Light Nuclei Yield Ratio in Relativistic Heavy Ion Collisions

    Kai-Jia Sun🇺🇸 · Wen-Hao Zhou🇨🇳 · Lie-Wen Chen🇨🇳 · Che Ming Ko🇺🇸 · Feng Li🇨🇳 · Rui Wang🇨🇳 · Jun Xu🇨🇳

    Using a relativistic transport model to describe the evolution of the quantum chromodynamic matter produced in Au+Au collisions at $\sqrt{s_{NN}}=3-200$ GeV, we study the effect of a first-order phase transition in the equation of state of this matter on the yield ratio $N_t{N}_p/N_d^2$ ($tp/d^2$) of produced proton ($p$), deuteron ($d$), and triton ($t$). We find that the large density inhomogeneities generated by the spinodal instability during the first-order phase transition can survive the fast expansion of the subsequent hadronic matter and lead to an enhanced $tp/d^2$ in central collisions at $\sqrt{s_{NN}}=3-5$ GeV as seen in the experiments by the STAR Collaboration and the E864 Collaboration. However, this enhancement subsides with increasing collision centrality, and the resulting almost flat centrality dependence of $tp/d^2$ at $\sqrt{s_{NN}}=3$ GeV can also be used as a signal for the first-order phase transition.

    ↳ nucl-thhep-ph13 citations
31. 31*

    Note on fundamental physics tests from black hole imaging: Comment on "Hunting for extra dimensions in the shadow of Sagittarius A${}^{\ast }$"

    Sunny Vagnozzi🇬🇧 · Luca Visinelli🇨🇳

    Several works over the past years have discussed the possibility of testing fundamental physics using Very Long Baseline Interferometry horizon-scale black hole (BH) images, such as the Event Horizon Telescope (EHT) images of M87${}^{\ast }$ and Sagittarius A${}^{\ast }$ (Sgr A${}^{\ast }$), using the size $r_{\mathrm{sh}}$ and deviation from circularity $\Delta \mathcal{C}$ of the BH shadow. For the case of the EHT image of Sgr A${}^{\ast }$, limits on $\Delta \mathcal{C}$ are not available due to the sparse interferometric coverage of the 2017 observations, alongside the short variability timescale of Sgr A${}^{\ast }$ compared to M87${}^{\ast }$. Concerning this point, we comment on the results of a recent preprint which purports to have derived new limits on extra dimensions using the deviation from circularity of Sgr A${}^{\ast }$'s shadow. The latter is quoted to be $\lesssim 10\%$ as with M87${}^{\ast }$, based on the "similarity" of the two shadows: however, this is an incorrect assumption, invalidating the subsequent results. In the immediate future, the simplest tests of fundamental physics from Sgr A${}^{\ast }$'s image will therefore mostly have to rely on $r_{\mathrm{sh}}$, whereas additional observables such as the photon ring and azimuthal angle lapse should soon be available and allow for novel tests.

    ↳ astro-ph.GAastro-ph.COgr-qchep-ph+1Res.Notes AAS(2022)·18 citations
32. 32*

    Resonance form factors from finite-volume correlation functions with the external field method

    Jonathan Lozano🇩🇪 · Ulf-G. Meißner🇩🇪 · Fernando Romero-López🇺🇸 · Akaki Rusetsky🇩🇪 · Gerrit Schierholz🇩🇪

    A novel method for the extraction of form factors of unstable particles on the lattice is proposed. The approach is based on the study of two-particle scattering in a static, spatially periodic external field by using a generalization of the Lüscher method in the presence of such a field. It is shown that the resonance form factor is given by the derivative of the resonance pole position in the complex plane with respect to the coupling constant to the external field. Unlike the standard approach, this proposal does not suffer from problems caused by the presence of the triangle diagram.

    ↳ hep-lathep-phnucl-thJHEP(2022)·11 citations
33. 33*

    Cosmological parameters from Planck data in SU(2)${}_{\mathrm{CMB}}$, their local $\Lambda$CDM values, and the modified photon Boltzmann equation

    Ralf Hofmann🇩🇪 · Janning Meinert🇩🇪 · Shyam Sunder Balaji🇩🇪

    A review of the spatially flat cosmological model SU(2)${}_{\mathrm{CMB}}$, minimally induced by the postulate that the Cosmic Microwave Background (CMB) is subject to an SU(2) rather than a U(1) gauge principle, is given. Cosmological parameter values, which are determined from the Planck CMB power spectra at small angular scales, are compared to their values in spatially flat $\Lambda$CDM from both local and global extractions. As a global model SU(2)${}_{\mathrm{CMB}}$ leans towards local $\Lambda$CDM cosmology and is in tension with some global $\Lambda$CDM parameter values. We present spectral antiscreening / screening effects in SU(2)${}_{\mathrm{CMB}}$ radiance within the Rayleigh-Jeans regime in dependence on temperature and frequency. Such radiance anomalies can cause CMB large-angle anomalies. Therefore, it is pointed out how SU(2)${}_{\mathrm{CMB}}$ modifies the Boltzmann equation for the perturbations of the photon phase space distribution at low redshift and why this requires to the solve the $\ell$-hierarchy on a comoving momentum grid ($q$-grid) for all $z$.

    ↳ hep-thastro-ph.COhep-phAnnalen Phys.(2023)·6 citations
34. 34*

    Study of $I=0$ bottomonium bound states and resonances in $S$, $P$, $D$ and $F$ waves with lattice QCD static-static-light-light potentials

    Pedro Bicudo🇵🇹 · Nuno Cardoso🇵🇹 · Lasse Mueller🇩🇪 · Marc Wagner🇩🇪

    In this paper we study $I=0$ bottomonium in $S$, $P$, $D$ and $F$ waves considering five coupled channels, one confined quarkonium and four open $B^{(\ast )}{\bar{B}}^{(\ast )}$ and $B_s^{(\ast )}{\bar{B}}_s^{(\ast )}$ meson-meson channels. To this end we use and extend a recently developed novel approach utilizing lattice QCD string breaking potentials for the study of quarkonium bound states and resonances. This approach is based on the Born Oppenheimer approximation and the unitary emergent wave method and allows to compute the poles of the $\text{mbox}T$ matrix. We compare our results to existing experimental results for $I=0$ bottomonium and discuss masses, decay widths and the assignment of angular momentum quantum numbers. Moreover, we determine the quarkonium and meson-meson composition of these states to clarify, which of them are ordinary quarkonium, and which of them should rather be interpreted as tetraquarks.

    ↳ hep-lathep-phPRD(2023)·27 citations
35. 35*

    Two-loop power spectrum with full time- and scale-dependence and EFT corrections: impact of massive neutrinos and going beyond EdS

    Mathias Garny🇩🇪 · Petter Taule🇩🇪

    We compute the density and velocity power spectra at next-to-next-to-leading order taking into account the effect of time- and scale-dependent growth of massive neutrino perturbations as well as the departure from Einstein--de-Sitter (EdS) dynamics at late times non-linearly. We determine the impact of these effects by comparing to the commonly adopted approximate treatment where they are not included. For the bare cold dark matter (CDM)+baryon spectrum, we find percent deviations for $k\gtrsim 0.17h{\mathrm{Mpc}}^{-1}$, mainly due to the departure from EdS. For the velocity and cross power spectrum the main difference arises due to time- and scale-dependence in presence of massive neutrinos yielding percent deviation above $k\simeq 0.08,0.13,0.16h{\mathrm{Mpc}}^{-1}$ for $\sum m_{\nu }=0.4,0.2,0.1\mathrm{eV}$, respectively. We use an effective field theory (EFT) framework at two-loop valid for wavenumbers $k\gg k_{\mathrm{FS}}$, where $k_{\mathrm{FS}}$ is the neutrino free-streaming scale. Comparing to Quijote N-body simulations, we find that for the CDM+baryon density power spectrum the effect of neutrino perturbations and exact time-dependent dynamics at late times can be accounted for by a shift in the one-loop EFT counterterm, $\Delta {\bar{\gamma }}_1\simeq -0.2{\mathrm{Mpc}}^2/h^2$. We find percent agreement between the perturbative and N-body results up to $k\lesssim 0.12h{\mathrm{Mpc}}^{-1}$ and $k\lesssim 0.16h{\mathrm{Mpc}}^{-1}$ at one- and two-loop order, respectively, for all considered neutrino masses $\sum m_{\nu }\le 0.4\mathrm{eV}$.

    ↳ astro-ph.COhep-phJCAP(2022)·28 citations
36. 36*

    Identifying magnetic antiskyrmions while they form with convolutional neural networks

    Jack Y. Araz🇬🇧 · Juan Carlos Criado🇬🇧 · Michael Spannowsky🇬🇧

    Chiral magnets have attracted a large amount of research interest in recent years because they support a variety of topological defects, such as skyrmions and bimerons, and allow for their observation and manipulation through several techniques. They also have a wide range of applications in the field of spintronics, particularly in developing new technologies for memory storage devices. However, the vast amount of data generated in these experimental and theoretical studies requires adequate tools, among which machine learning is crucial. We use a Convolutional Neural Network (CNN) to identify the relevant features in the thermodynamical phases of chiral magnets, including (anti-)skyrmions, bimerons, and helical and ferromagnetic states. We use a flexible multi-label classification framework that can correctly classify states in which different features and phases are mixed. We then train the CNN to predict the features of the final state from snapshots of intermediate states of a lattice Monte Carlo simulation. The trained model allows identifying the different phases reliably and early in the formation process. Thus, the CNN can significantly speed up the large-scale simulations for 3D materials that have been the bottleneck for quantitative studies so far. Moreover, this approach can be applied to the identification of mixed states and emerging features in real-world images of chiral magnets.

    ↳ cond-mat.str-elcond-mat.mtrl-scics.LGhep-phJ.Magn.Magn.Mater.(2022)·0 citations
37. 37*

    Interpretation of the observed neutrino emission from three Tidal Disruption Events

    Walter Winter🇩🇪 · Cecilia Lunardini🇺🇸

    Three Tidal Disruption Event (TDE) candidates (AT2019dsg, AT2019fdr, AT2019aalc) have been associated with high energy astrophysical neutrinos in multi-messenger follow-ups. In all cases, the neutrino observation occurred O(100) days after the maximum of the optical-ultraviolet (OUV) luminosity. We discuss unified fully time-dependent interpretations of the neutrino signals where the neutrino delays are not a statistical effect, but rather the consequence of a physical scale of the post-disruption system. Noting that X-rays flares and infrared (IR) dust echoes have been observed in all cases, we consider three models in which quasi-isotropic neutrino emission is due to the interactions of accelerated protons of moderate, medium, and ultra-high energies with X-rays, OUV, and IR photons, respectively. We find that the neutrino time delays can be well described in the X-ray model assuming magnetic confinement of protons in a calorimetric approach if the unobscured X-ray luminosity is roughly constant over time, and in the IR model, where the delay is directly correlated with the time evolution of the echo luminosity (for which a model is developed here). The OUV model exhibits the highest neutrino production efficiency. In all three models, the highest neutrino fluence is predicted for AT2019aalc, due to its high estimated supermassive black hole mass and low redshift. All models result in diffuse neutrino fluxes that are consistent with observations.

    ↳ astro-ph.HEhep-phApJ(2023)·67 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.