Mon·Feb 22, 2021Monday·February 22, 2021

1. 01*

   The Doubly-heavy Tetraquarks ($q{q}^{\prime }\bar{Q}\overline{Q^{\prime }}$) in a Constituent Quark Model with a Complete Set of Harmonic Oscillator Bases

   Sungsik Noh🇰🇷 · Woosung Park🇰🇷 · Su Houng Lee🇰🇷

   We have improved our previous variational method based constituent quark model by introducing a complete set of 3-dimensional harmonic oscillator bases as the spatial part of the total wave function. To assess the validity of our approach, we compared the binding energy, thus calculated with the exact value for the hydrogen model. After fitting to the masses of the ground state hadrons, we apply our new method to analyze the doubly-heavy tetraquark states $q{q}^{\prime }\bar{Q}\overline{Q^{\prime }}$ and compared the result for the binding energies with that from other works. We also calculated the ground state masses of $T_{sc}(ud\bar{s}\bar{c})$ and $T_{sb}(ud\bar{s}\bar{b})$ with $(I,S)=(0,1),(0,2)$. We found that $T_{bb}(ud\bar{b}\bar{b})$ and $us\bar{b}\bar{b}$, both with $(I,S)=(0,1)$, are stable against the two lowest threshold meson states with binding energies $-145$ MeV and $-42$ MeV, respectively. We further found that $T_{cb}(ud\bar{c}\bar{b})$ is near the lowest threshold. The spatial sizes for the tetraquarks are also discussed.

   hep-phnucl-thPRD(2021)·53 citations
2. 02*

   Four-loop collinear anomalous dimensions in QCD and $\mathcal{N}=4$ super Yang-Mills

   Bakul Agarwal🇺🇸 · Andreas von Manteuffel🇺🇸 · Erik Panzer🇬🇧 · Robert M. Schabinger🇺🇸

   We calculate the collinear anomalous dimensions in massless four-loop QCD and $\mathcal{N}=4$ supersymmetric Yang-Mills theory from the infrared poles of vertex form factors. We give very precise numerical approximations and a conjecture for the complete analytic results in both models we consider.

   hep-phhep-thPLB(2021)·80 citations
3. 03*

   Deep inelastic scattering as a probe of entanglement: confronting experimental data

   Dmitri E. Kharzeev (Stony Brook U./BNL)🇺🇸 · Eugene Levin (Tel Aviv U./UTFSM)🇮🇱

   Parton distributions can be defined in terms of the entropy of entanglement between the spatial region probed by deep inelastic scattering (DIS) and the rest of the proton. For very small $x$, the proton becomes a maximally entangled state. This approach leads to a simple relation $S=\ln N$ between the average number $N$ of color-singlet dipoles in the proton wave function and the entropy of the produced hadronic state $S$. At small $x$, the multiplicity of dipoles is given by the gluon structure function, $N=xG(x,Q^2)$. Recently, the H1 Collaboration analyzed the entropy of the produced hadronic state in DIS, and studied its relation to the gluon structure function; poor agreement with the predicted relation was found. In this letter we argue that a more accurate account of the number of color-singlet dipoles in the kinematics of H1 experiment (where hadrons are detected in the current fragmentation region) is given not by $xG(x,Q^2)$ but by the sea quark structure function $x\Sigma (x,Q^2)$. Sea quarks originate from the splitting of gluons, so at small $x$ $x\Sigma (x,Q^2)\sim xG(x,Q^2)$, but in the current fragmentation region this proportionality is distorted by the contribution of the quark-antiquark pair produced by the virtual photon splitting. In addition, the multiplicity of color-singlet dipoles in the current fragmentation region is quite small, and one needs to include $\sim 1/N$ corrections to $S=\ln N$ asymptotic formula. Taking both of these modifications into account, we find that the data from the H1 Collaboration in fact agree well with the prediction based on entanglement.

   hep-phhep-exPRD(2021)·74 citations
4. 04*

   The phenomenology of nuclear scattering for a WIMP of arbitrary spin

   Paolo Gondolo (Utah U.)🇺🇸 · Injun Jeong🇰🇷 · Sunghyun Kang🇰🇷 · Stefano Scopel (Sogang U.)🇰🇷 · Gaurav Tomar (Technical U. of Munich)🇩🇪

   We provide a first systematic and quantitative discussion of the phenomenology of the non-relativistic effective Hamiltonian describing the nuclear scattering process for a Weakly Interacting Massive Particle (WIMP) of arbitrary spin $j_{\chi }$. To this aim we obtain constraints from a representative sample of present direct detection experiments assuming the WIMP-nucleus scattering process to be driven by each one of the 44 effective couplings that arise for $j_{\chi }\le$ 2. We find that a high value of the multipolarity $s\le 2j_{\chi }$ of the coupling, related to the power of the momentum transfer $q$ appearing in the scattering amplitude, leads to a suppression of the expected rates and pushes the expected differential spectra to large recoil energies $E_R$. For $s\le$ 4 the effective scales probed by direct detection experiments can be suppressed by up to 5 orders of magnitude compared to the case of a standard spin-independent interaction. For operators with large $s$ the expected differential spectra can be pushed to recoil energies in the MeV range, with the largest part of the signal concentrated at $E_R\gtrsim$ 100 keV and a peculiar structure of peaks and minima arising when both the nuclear target and the WIMP are heavy. As a consequence the present bounds on the effective operators can be significantly improved by extending the recoil energy intervals to higher recoil energies. Our analysis assumes effective interaction operators that are irreducible under the rotation group. Such operators drive the interactions of high-multipole dark matter candidates, i.e. states that possess only the highest multipole allowed by their spin. As a consequence our analysis represents also the first phenomenological study of the direct detection of quadrupolar, octupolar, and hexadecapolar dark matter.

   hep-phastro-ph.COPRD(2021)·14 citations
5. 05*

   Constraints on general neutrino interactions with exotic fermion from neutrino-electron scattering experiments

   Zikang Chen🇨🇳 · Tong Li🇨🇳 · Jiajun Liao🇨🇳

   The couplings between the neutrinos and exotic fermion can be probed in both neutrino scattering experiments and dark matter direct detection experiments. We present a detailed analysis of the general neutrino interactions with an exotic fermion and electrons at neutrino-electron scattering experiments. We obtain the constraints on the coupling coefficients of the scalar, pseudoscalar, vector, axialvector, tensor and electromagnetic dipole interactions from the CHARM-II, TEXONO and Borexino experiments. For the flavor-universal interactions, we find that the Borexino experiment sets the strongest bounds in the low mass region for the electromagnetic dipole interactions, and the CHARM-II experiment dominates the bounds for other scenarios. If the interactions are flavor dependent, the bounds from the CHARM-II or TEXONO experiment can be avoided, and there are correlations between the flavored coupling coefficients for the Borexino experiment. We also discuss the detection of sub-MeV DM absorbed by bound electron targets and illustrate that the vector coefficients preferred by XENON1T data is allowed by the neutrino experiments.

   hep-phJHEP(2021)·26 citations
6. 06*

   The Singly-Charged Scalar Singlet as the Origin of Neutrino Masses

   Tobias Felkl🇦🇺 · Juan Herrero-Garcia🇪🇸 · Michael A. Schmidt🇦🇺

   We consider the generation of neutrino masses via a singly-charged scalar singlet. Under general assumptions we identify two distinct structures for the neutrino mass matrix. This yields a constraint for the antisymmetric Yukawa coupling of the singly-charged scalar singlet to two left-handed lepton doublets, irrespective of how the breaking of lepton-number conservation is achieved. The constraint disfavours large hierarchies among the Yukawa couplings. We study the implications for the phenomenology of lepton-flavour universality, measurements of the $W$-boson mass, flavour violation in the charged-lepton sector and decays of the singly-charged scalar singlet. We also discuss the parameter space that can address the Cabibbo Angle Anomaly.

   hep-phJHEP(2021)·24 citations
7. 07*

   Minimal warm inflation with complete medium response

   M. Laine🇨🇭 · S. Procacci🇨🇭

   If a homogeneous field evolves within a medium, with the latter gradually picking up a temperature, then the friction felt by the field depends on how its evolution rate compares with medium time scales. We suggest a framework which permits to incorporate the contributions from all medium time scales. As an example, we illustrate how warm axion inflation can be described by inputting the retarded pseudoscalar correlator of a thermal Yang-Mills plasma. Adopting a semi-realistic model for the latter, and starting the evolution at almost vanishing temperature, we show how the system heats up and then enters the "weak" or "strong" regime of warm inflation. Previous approximate treatments are scrutinized.

   hep-phastro-ph.COJCAP(2021)·57 citations
8. 08*

   Evolution of initial stage fluctuations in the glasma

   Pablo Guerrero-Rodríguez🇫🇮 · Tuomas Lappi🇫🇮

   We perform a calculation of the one- and two-point correlation functions of energy density and axial charge deposited in the glasma in the initial stage of a heavy ion collision at finite proper time. We do this by describing the initial stage of heavy ion collisions in terms of freely evolving classical fields whose dynamics obey the linearized Yang-Mills equations. Our approach allows us to systematically resum the contributions of high momentum modes that would make a power series expansion in proper time divergent. We evaluate the field correlators in the McLerran-Venugopalan model using the glasma graph approximation, but our approach for the time dependence can be applied to a general four-point function of the initial color fields. Our results provide analytical insight into the preequilibrium phase of heavy ion collisions without requiring a numerical solution to the Yang-Mills equations.

   hep-phnucl-thPRD(2021)·18 citations
9. 09*

   QCD factorization of the four-lepton decay $B^{-}\to \ell {\bar{\nu }}_{\ell }{\ell }^{(\prime )}{\bar{\ell }}^{(\prime )}$

   Martin Beneke🇩🇪 · Philipp Böer🇩🇪 · Panagiotis Rigatos🇩🇪 · Kimberley Keri Vos🇳🇱

   Motivated by the first search for the rare charged-current $B$ decay to four leptons, $\ell {\bar{\nu }}_{\ell }{\ell }^{(\prime )}{\bar{\ell }}^{(\prime )}$, we calculate the decay amplitude with factorization methods. We obtain the $B\to {\gamma }^{\ast }$ form factors, which depend on the invariant masses of the two lepton pairs, at leading power in an expansion in ${\Lambda }_{\mathrm{QCD}}/m_b$ to next-to-leading order in ${\alpha }_s$, and at $\mathcal{O}({\alpha }_s^0)$ at next-to-leading power. Our calculations predict branching fractions of a few times $10^{-8}$ in the ${\ell }^{(\prime )}{\bar{\ell }}^{(\prime )}$ mass-squared bin up to $q^2=1{\text{GeV}}^2$ with $n_{+}q>3$GeV. The branching fraction rapidly drops with increasing $q^2$. An important further motivation for this investigation has been to explore the sensitivity of the decay rate to the inverse moment ${\lambda }_B$ of the leading-twist $B$ meson light-cone distribution amplitude. We find that in the small-$q^2$ bin, the sensitivity to ${\lambda }_B$ is almost comparable to $B^{-}\to {\ell }^{-}{\bar{\nu }}_{\ell }\gamma$ when ${\lambda }_B$ is small, but with an added uncertainty from the light-meson intermediate resonance contribution. The sensitivity degrades with larger $q^2$.

   hep-phEPJC(2021)·28 citations
10. 10*

    Challenges for a QCD Axion at the 10 MeV Scale

    Jia Liu🇨🇳 · Navin McGinnis🇨🇦 · Carlos E.M. Wagner🇺🇸 · Xiao-Ping Wang🇨🇳

    We report on an interesting realization of the QCD axion, with mass in the range $\mathcal{O}(10)$ MeV. It has previously been shown that although this scenario is stringently constrained from multiple sources, the model remains viable for a range of parameters that leads to an explanation of the Atomki experiment anomaly. In this article we study in more detail the additional constraints proceeding from recent low energy experiments and study the compatibility of the allowed parameter space with the one leading to consistency of the most recent measurements of the electron anomalous magnetic moment and the fine structure constant. We further provide an ultraviolet completion of this axion variant and show the conditions under which it may lead to the observed quark masses and CKM mixing angles, and remain consistent with experimental constraints on the extended scalar sector appearing in this Standard Model extension. In particular, the decay of the Standard Model-like Higgs boson into two light axions may be relevant and leads to a novel Higgs boson signature that may be searched for at the LHC in the near future.

    hep-phJHEP(2021)·26 citations
11. 11*

    Dissipative Dark Matter on FIRE: I. Structural and kinematic properties of dwarf galaxies

    Xuejian Shen🇺🇸 · Philip F. Hopkins🇺🇸 · Lina Necib🇺🇸 · Fangzhou Jiang🇺🇸 · Michael Boylan-Kolchin🇺🇸 · Andrew Wetzel🇺🇸

    We present the first set of cosmological baryonic zoom-in simulations of galaxies including dissipative self-interacting dark matter (dSIDM). These simulations utilize the Feedback In Realistic Environments (FIRE-2) galaxy formation physics, but allow the dark matter to have dissipative self-interactions analogous to Standard Model forces, parameterized by the self-interaction cross-section per unit mass, $(\sigma /m)$, and the dimensionless degree of dissipation, $0<f_{\mathrm{diss}}<1$. We survey this parameter space, including constant and velocity-dependent cross-sections, and focus on structural and kinematic properties of dwarf galaxies with $M_{\mathrm{halo}}\simeq 10^{10-11}{\mathrm{M}}_{\odot }$. Central density profiles of simulated dwarfs become cuspy when $(\sigma /m{)}_{\mathrm{eff}}\gtrsim 0.1\mathrm{c}{\mathrm{m}}^2{\mathrm{g}}^{-1}$ (and $f_{\mathrm{diss}}=0.5$ as fiducial). The power-law slopes asymptote to $\alpha \approx -1.5$ in low-mass dwarfs independent of cross-section, which arises from a dark matter "cooling flow". Through comparisons with dark matter only simulations, we find the profile in this regime is insensitive to the inclusion of baryons. However, when $(\sigma /m{)}_{\mathrm{eff}}\ll 0.1\mathrm{c}{\mathrm{m}}^2{\mathrm{g}}^{-1}$, baryonic effects can produce cored density profiles comparable to non-dissipative cold dark matter (CDM) runs but at smaller radii. Simulated galaxies with $(\sigma /m)\gtrsim 10\mathrm{c}{\mathrm{m}}^2{\mathrm{g}}^{-1}$ develop significant coherent rotation of dark matter, accompanied by halo deformation, but this is unlike the well-defined thin "dark disks" often attributed to baryon-like dSIDM. The density profiles in this high cross-section model exhibit lower normalizations given the onset of halo deformation. For our surveyed dSIDM parameters, halo masses and galaxy stellar masses do not show appreciable difference from CDM, but dark matter kinematics and halo concentrations/shapes can differ.

    ↳ astro-ph.GAastro-ph.COhep-phMNRAS(2021)·58 citations
12. 12*

    Determination of ${\overline{m}}_b/{\overline{m}}_c$ and ${\overline{m}}_b$ from $n_f=4$ lattice QCD$+$QED

    D. Hatton🇬🇧 · C. T. H. Davies🇬🇧 · J. Koponen🇩🇪 · G. P. Lepage🇺🇸 · A. T. Lytle🇺🇸

    We extend HPQCD's earlier $n_f=4$ lattice-QCD analysis of the ratio of $\overline{\mathrm{MSB}}$ masses of the $b$ and $c$ quark to include results from finer lattices (down to 0.03fm) and a new calculation of QED contributions to the mass ratio. We find that ${\overline{m}}_b(\mu )/{\overline{m}}_c(\mu )=4.586(12)$ at renormalization scale $\mu =3$\,GeV. This result is nonperturbative. Combining it with HPQCD's recent lattice QCD$+$QED determination of ${\overline{m}}_c(3\mathrm{GeV})$ gives a new value for the $b$-quark mass: ${\overline{m}}_b(3\mathrm{GeV})=4.513(26)$GeV. The $b$-mass corresponds to ${\overline{m}}_b({\overline{m}}_b,n_f=5)=4.202(21)$GeV. These results are the first based on simulations that include QED.

    ↳ hep-lathep-phPRD(2021)·28 citations
13. 13*

    Trans-Planckian Censorship Conjecture and Early Universe Cosmology

    Robert Brandenberger (McGill University)🇨🇦

    I review the "Trans-Planckian Censorship Conjecture" (TCC) and its implications for cosmology, in particular for the inflationary universe scenario. Whereas the inflationary scenario is tightly constrained by the TCC, alternative early universe scenarios are not restricted.

    ↳ hep-thastro-ph.COgr-qchep-phLHEP(2021)·69 citations
14. 14*

    Spiky strings in de Sitter space

    Mitsuhiro Kato🇯🇵 · Kanji Nishii🇯🇵 · Toshifumi Noumi🇯🇵 · Toshiaki Takeuchi🇯🇵 · Siyi Zhou🇸🇪

    We study semiclassical spiky strings in de Sitter space and the corresponding Regge trajectories, generalizing the analysis in anti-de Sitter space. In particular we demonstrate that each Regge trajectory has a maximum spin due to de Sitter acceleration, similarly to the folded string studied earlier. While this property is useful for the spectrum to satisfy the Higuchi bound, it makes a nontrivial question how to maintain mildness of high-energy string scattering which we are familiar with in flat space and anti-de Sitter space. Our analysis implies that in order to have infinitely many higher spin states, one needs to consider infinitely many Regge trajectories with an increasing folding number.

    ↳ hep-thgr-qchep-phJHEP(2021)·5 citations
15. 15*

    Screening masses towards chiral limit

    Simon Dentinger🇩🇪 · Olaf Kaczmarek🇩🇪 · Anirban Lahiri🇩🇪

    A possible effective restoration of the anomalous $U_A(1)$ symmetry would have a non-trivial effect on the global phase diagram of QCD. In this work we investigate the effective restoration of the $U_A(1)$ through the calculation of scalar and pseudo-scalar screening masses and corresponding susceptibilities, for physical and lower than physical pion masses. Calculations have been performed in (2+1)-flavor HISQ discretization scheme with a physical value of the strange quark mass. Preliminary calculations of the continuum extrapolated scalar and pseudo-scalar masses are presented, based on lattices with three different temporal extent. Non-trivial structure of the difference between scalar and pseudo-scalar susceptibilites are discussed for $N_{\tau }=8$ lattices.

    ↳ hep-lathep-phnucl-thActa Phys.Polon.Supp.(2021)·8 citations
16. 16*

    Germanium response to sub-keV nuclear recoils: a multipronged experimental characterization

    J.I. Collar🇺🇸 · A.R.L. Kavner🇺🇸 · C.M. Lewis🇺🇸

    Germanium is the detector material of choice in many rare-event searches looking for low-energy nuclear recoils induced by dark matter particles or neutrinos. We perform a systematic exploration of its quenching factor for sub-keV nuclear recoils, using multiple techniques: photo-neutron sources, recoils from gamma-emission following thermal neutron capture, and a monochromatic filtered neutron beam. Our results point to a marked deviation from the predictions of the Lindhard model in this mostly unexplored energy range. We comment on the compatibility of our data with low-energy processes such as the Migdal effect, and on the impact of our measurements on upcoming searches.

    ↳ nucl-exastro-ph.COhep-exhep-phPRD(2021)·87 citations
17. 17*

    Catastrophic Production of Slow Gravitinos

    Edward W. Kolb🇺🇸 · Andrew J. Long🇺🇸 · Evan McDonough🇺🇸

    We study gravitational particle production of the massive spin-$3/2$ Rarita-Schwinger field, and its close relative, the gravitino, in FRW cosmological spacetimes. For masses lighter than the value of the Hubble expansion rate after inflation, $m_{3/2}\lesssim H$, we find catastrophic gravitational particle production, wherein the number of gravitationally produced particles is divergent, caused by a transient vanishing of the helicity-1/2 gravitino sound speed. In contrast with the conventional gravitino problem, the spectrum of produced particles is dominated by those with momentum at the UV cutoff. This suggests a breakdown of effective field theory, which might be cured by new degrees of freedom that emerge in the UV. We study the UV completion of the Rarita-Schwinger field, namely $\mathcal{N}=1$, $d=4$, supergravity. We reproduce known results for models with a single superfield and models with an arbitrary number of chiral superfields, find a simple geometric expression for the sound speed in the latter case, and extend this to include nilpotent constrained superfields and orthogonal constrained superfields. We find supergravity models where the catastrophe is cured and models where it persists. Insofar as quantizing the gravitino is tantamount to quantizing gravity, as is the case in any UV completion of supergravity, the models exhibiting catastrophic production are prime examples of 4-dimensional effective field theories that become inconsistent when gravity is quantized, suggesting a possible link to the Swampland program. We propose the Gravitino Swampland Conjecture, which is consistent with and indeed follows from the KKLT and Large Volume scenarios for moduli stabilization in string theory.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2021)·55 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.