Wed·Nov 20, 2019Wednesday·November 20, 2019

1. 01*

   On the Wondrous Stability of ALP Dark Matter

   Gonzalo Alonso-Álvarez🇩🇪 · Rick S. Gupta🇬🇧 · Joerg Jaeckel🇩🇪 · Michael Spannowsky🇬🇧

   The very low mass and small coupling of axion-like particles (ALPs) is usually taken as a guarantor of their cosmological longevity, making them excellent dark matter candidates. That said, Bose enhancement could stimulate decays and challenge this paradigm. Here, we analyze and review the cosmological decay of ALPs into photons, taking Bose enhancement into account, thereby going beyond the usual naive perturbative estimate. At first glance, this calculation seems to yield an exponentially growing resonance and therefore an extremely fast decay rate. However, the redshifting of the decay products due to the expansion of the Universe as well as the effective plasma mass of the photon can prevent an efficient resonance. While this result agrees with existing analyses of the QCD axion, for more general ALPs that can feature an enhanced photon coupling, stability is only ensured by a combination of the expansion and the plasma effects.

   hep-phastro-ph.COJCAP(2020)·49 citations
2. 02*

   Rare ${\Lambda }_b\to \Lambda l^{+}{l}^{-}$ decay in the Bethe-Salpeter equation approach

   Liang-Liang Liu🇨🇳 · Xian-Wei Kang🇨🇳 · Zhen-Yang Wang🇨🇳 · Xin-Heng Guo🇨🇳

   We study the rare decays ${\Lambda }_b\to \Lambda l^{+}{l}^{-}(l=e,\mu ,\tau )$ in the Bethe-Salpeter equation approach. We find that depending on the values of parameters in our model the branching ratio $Br({\Lambda }_b\to \Lambda {\mu }^{+}{\mu }^{-})\times 10^6$ varies from $0.812$ to $1.445$ when $\kappa =0.050\sim 0.060$ GeV${}^3$ and the binding energy $E_0=-0.14$ GeV while $Br({\Lambda }_b\to \Lambda {\mu }^{+}{\mu }^{-})\times 10^6$ varies from $1.051$ to $1.098$ when $\kappa =0.055$ Gev${}^3$ and the binding energy $E_0$ changes from $-0.19$ to $-0.09$ GeV. These results agree with the experimental data. In the same parameter regions, we find that the branching ratio $Br({\Lambda }_b\to \Lambda e^{+}{e}^{-}({\tau }^{+}{\tau }^{-}))\times 10^6$ varies in the range $0.660-1.028$ ($0.252-0.392$) and $0.749-1.098$ ($0.286-0.489$), respectively.

   hep-phCPC(2020)·8 citations
3. 03*

   Semileptonic decays of $D$ and $D_s$ mesons in the relativistic quark model

   R. N. Faustov🇷🇺 · V. O. Galkin🇷🇺 · Xian-Wei Kang🇨🇳

   The form factors parameterizing the weak $D$ and $D_s$ transitions to light pseudoscalar and vector mesons are calculated in the framework of the relativistic quark model based on the quasipotential approach. The special attention is paid to the systematic account of the relativistic effects including transformation of the meson wave function from the rest to moving reference frame and contributions of the intermediate negative-energy states. The form factors are expressed through the overlap integrals of the meson wave functions, which are taken from previous studies of meson spectroscopy. They are calculated in the whole range of the transferred momentum $q^2$. Convenient parameterization of the form factors which accurately reproduces numerical results is given. The obtained values of the form factors and their ratios at $q^2=0$ agree well with the ones extracted form the experimental data. On the basis of these form factors and helicity formalism, differential and total semileptonic decay rates of $D$ and $D_s$ mesons as well as different asymmetries and polarization parameters are calculated. The detailed comparison of the obtained results with other theoretical calculations and experimental data is given.

   hep-phhep-exPRD(2020)·84 citations
4. 04*

   Electroweak boson production at large transverse momentum in double polarized $pp$ scattering at next-to-leading order accuracy

   Daniel de Florian🇦🇷 · Iván Pedron🇦🇷

   We compute the next-to-leading order corrections to the cross section for the production of electroweak gauge bosons ($Z$, $W^{\pm }$ and ${\gamma }^{\ast }$) with large transverse momentum in double (longitudinally) polarized hadronic collisions. The calculation is fully performed in the HVBM scheme within dimensional regularization with a careful treatment of issues arising due to the appearance of ${\gamma }^5$ in polarization projectors and axial couplings. We study the phenomenological consequences of the NLO corrections at the level of both the double polarized cross section and the corresponding asymmetries at RHIC kinematics.

   hep-phPRD(2020)·0 citations
5. 05*

   Spin effects in neutrino gravitational scattering

   Maxim Dvornikov (IZMIRAN)🇷🇺

   We study spin oscillations of neutrinos gravitationally scattered off a nonrotating black hole (BH). We derive the transition and survival probabilities of spin oscillations in quadratures when neutrinos interacts with BH only. The dependence of the probabilities on the impact parameter is analyzed. Then, we obtain the effective Schrödinger equation for neutrino spin oscillations in neutrino scattering off BH surrounded by background matter. This equation is solved numerically in the case of a supermassive BH with a realistic accretion disk. We find that the observed neutrino fluxes can be reduced almost 20% because of spin oscillations when neutrinos experience gravitational scattering. The neutrino interaction with an accretion disk results in the additional asymmetry in the intensities of outgoing fluxes depending on the neutrino trajectory.

   hep-phastro-ph.HEgr-qcPRD(2020)·28 citations
6. 06*

   The Light Higgsino-dominated NLSPs in the Semi-constrained NMSSM

   Kun Wang🇨🇳 · Jingya Zhu🇨🇳

   In the semi-constrained NMSSM (scNMSSM, or NMSSM with non-universal Higgs mass) under current constraints, we consider a scenario where $h_2$ is the SM-like Higgs, ${\tilde{\chi }}_1^0$ is singlino-dominated LSP, ${\tilde{\chi }}_1^{\pm }$ and ${\tilde{\chi }}_{2,3}^0$ are mass-degenerated, light and higgsino-dominated NLSPs (next-to-lightest supersymmetric particles). We investigate the constraints to these NLSPs from searching for SUSY particles at the LHC Run-I and Run-II, discuss the possibility of discovering these NLSPs in the future, and come to the following conclusions: (i) With all data of Run I and up to 36 $\mathrm{f}{\mathrm{b}}^{-1}$ data of Run II at the LHC, the search results by ATLAS and CMS can still not exclude the higgsino-dominated NLSPs of $100\sim 200$ GeV. (ii) When the mass difference with ${\tilde{\chi }}_1^0$ is smaller than $m_{h_2}$, ${\tilde{\chi }}_2^0$ and ${\tilde{\chi }}_3^0$ have opposite preference on decaying to $Z/Z^{\ast }$ or $h_1$. (iii) When the mass difference between NLSP and LSP is larger than $m_Z$, most of the samples can be checked at $5\sigma$ level with future 300 $\mathrm{f}{\mathrm{b}}^{-1}$ data at the LHC. While with 3000 $\mathrm{f}{\mathrm{b}}^{-1}$ data at the High Luminosity LHC (HL-LHC), nearly all of the samples can be checked at $5\sigma$ level even if the mass difference is insufficient. (iv) The $a_1$ funnel and the $h_2/Z$ funnel mechanisms for the singlino-dominated LSP annihilating can not be distinguished by searching for NLSPs.

   hep-phCPC(2020)·11 citations
7. 07*

   Effective-field theory analysis of the ${\tau }^{-}\to K^{-}({\eta }^{(\prime )},K^0){\nu }_{\tau }$ decays

   Sergi Gonzàlez-Solís🇺🇸 · Alejandro Miranda🇲🇽 · Javier Rendón🇲🇽 · Pablo Roig🇲🇽

   We analyze the decays ${\tau }^{-}\to K^{-}({\eta }^{(\prime )},K^0){\nu }_{\tau }$ within an effective field theory that includes the most general interactions between Standard Model fields up to dimension six, assuming left-handed neutrinos. In particular, we examine different interesting phenomenological observables i.e. decay spectra and branching ratio, Dalitz plot distributions and the forward-backward asymmetry, to explore the sensitivity of the corresponding decays to the effects of non-standard interactions. A controlled theoretical input on the Standard Model hadronic form factors, based on chiral symmetry, dispersion relations, data and asymptotic QCD properties, has allowed us to set bounds on the New Physics scalar and tensor effective couplings using the measured branching ratios. These are found to be in line with the findings of our series of previous analyses of two-meson tau decays and less precise than the constraints obtained from semileptonic kaon decays. In order to set stringent limits on these couplings, we will use all available experimental data of all possible di-meson tau decays. This is our next step plan, that we hope to be of interest for future experimental analyses of these decays.

   hep-phhep-exPRD(2020)·33 citations
8. 08*

   Doing spin physics with unpolarized particles

   Igor P. Ivanov🇵🇹 · Nikolai Korchagin🇨🇳 · Alexandr Pimikov🇨🇳 · Pengming Zhang🇨🇳

   Twisted, or vortex, particles refer to freely propagating non-plane-wave states with helicoidal wave fronts. In this state, the particle possesses a non-zero orbital angular momentum with respect to its average propagation direction. Twisted photons and electrons have been experimentally demonstrated, and creation of other particles in twisted states can be anticipated. If brought in collisions, twisted states offer a new degree of freedom to particle physics, and it is timely to analyze what new insights may follow. Here, we theoretically investigate resonance production in twisted photon collisions and twisted $e^{+}{e}^{-}$ annihilation and show that these processes emerge as a completely novel probe of spin and parity-sensitive observables in fully inclusive cross sections with unpolarized initial particles. This is possible because the initial state with a non-zero angular momentum explicitly breaks the left-right symmetry even when averaging over helicities. In particular, we show how one can produce almost $100\%$ polarized vector mesons in unpolarized twisted $e^{+}{e}^{-}$ annihilation and how to control its polarization state.

   hep-phhep-exquant-phPRL(2020)·42 citations
9. 09*

   Heavy Holographic QCD

   Nicolas Kovensky🇬🇧 · Andreas Schmitt🇬🇧

   We study the phase structure of the Witten-Sakai-Sugimoto model in the plane of temperature and baryon chemical potential, including the effect of a nonzero current quark mass. Our study is performed in the decompactified limit of the model, which, at least regarding the chiral phase transition, appears to be closer to real-world QCD than the original version. Following earlier studies, we account for the quark mass in an effective way based on an open Wilson line operator whose expectation value is identified with the chiral condensate. We find that the quark mass stabilizes a configuration with string sources and point out that this phase plays an important role in the phase diagram. Furthermore, we show that the quark mass breaks up the first-order chiral phase transition curve and introduces critical points to the phase diagram. Similarities of the phase structure to other holographic approaches and to lattice simulations of "heavy QCD" are found and discussed. By making holographic QCD more realistic, our results open the door to a better understanding of real-world strongly coupled hot and dense matter.

   hep-phhep-thJHEP(2020)·19 citations
10. 10*

    Axion Fragmentation

    Nayara Fonseca🇩🇪 · Enrico Morgante🇩🇪 · Ryosuke Sato🇩🇪 · Géraldine Servant🇩🇪

    We investigate the production of axion quanta during the early universe evolution of an axion-like field rolling down a wiggly potential. We compute the growth of quantum fluctuations and their back-reaction on the homogeneous zero-mode. We evaluate the transfer of kinetic energy from the zero mode to the quantum fluctuations and the conditions to decelerate the axion zero-mode as a function of the Hubble rate, the slope of the potential, the size of the barriers and the initial field velocity. We discuss how these effects impact the relaxion mechanism.

    hep-phastro-ph.COhep-thJHEP(2020)·86 citations
11. 11*

    Relaxion Fluctuations (Self-stopping Relaxion) and Overview of Relaxion Stopping Mechanisms

    Nayara Fonseca🇩🇪 · Enrico Morgante🇩🇪 · Ryosuke Sato🇩🇪 · Géraldine Servant🇩🇪

    In implementations of the electroweak scale cosmological relaxation mechanism proposed so far, the effect of the quantum fluctuations of the homogeneous relaxion field has been ignored. We show that they can grow during the classical cosmological evolution of the relaxion field passing through its many potential barriers. The resulting production of relaxion particles can act as an efficient stopping mechanism for the relaxion. We revisit the original relaxion proposal and determine under which conditions inflation may no longer be needed as a source of friction. We review alternative stopping mechanisms and determine in detail the allowed parameter space for each of them (whether happening before, during and after inflation), also considering and severely constraining the case of friction from electroweak gauge boson production in models with large and Higgs-independent barriers.

    hep-phastro-ph.COJHEP(2020)·41 citations
12. 12*

    A Random Clockwork of Flavor

    Fernando Abreu de Souza🇧🇷 · Gero von Gersdorff🇧🇷

    We propose a simple clockwork model of flavor which successfully generates the Standard Model flavor hierarchies from random order-one couplings. With very few parameters we achieve distributions of models in excellent agreement with observation. We explain in some detail the interpretation of our mechanism as random localization of zero modes in theory space. The scale of the vectorlike fermions is mostly constrained by lepton flavor violation with secondary constraints arising from rare meson decays.

    hep-phJHEP(2020)·12 citations
13. 13*

    Impact of Isolation and Fiducial Cuts on $q_T$ and N-Jettiness Subtractions

    Markus A. Ebert🇺🇸 · Frank J. Tackmann🇩🇪

    Kinematic selection cuts and isolation requirements are a necessity in experimental measurements for identifying prompt leptons and photons that originate from the hard-interaction process of interest. We analyze how such cuts affect the application of the $q_T$ and $N$-jettiness subtraction methods for fixed-order calculations. We consider both fixed-cone and smooth-cone isolation methods. We find that kinematic selection and isolation cuts both induce parametrically enhanced power corrections with considerably slower convergence compared to the standard power corrections that are already present in inclusive cross sections without additional cuts. Using analytic arguments at next-to-leading order we derive their general scaling behavior as a function of the subtraction cutoff. We also study their numerical impact for the case of gluon-fusion Higgs production in the $H\to \gamma \gamma$ decay mode and for $pp\to \gamma \gamma$ direct diphoton production. We find that the relative enhancement of the additional cut-induced power corrections tends to be more severe for $q_T$, where it can reach an order of magnitude or more, depending on the choice of parameters and subtraction cutoffs. We discuss how all such cuts can be incorporated without causing additional power corrections by implementing the subtractions differentially rather than through a global slicing method. We also highlight the close relation of this formulation of the subtractions to the projection-to-Born method.

    hep-phJHEP(2020)·61 citations
14. 14*

    Implications of the upper bound on $\mathbf{h}\to {\mathbf{\mu }}^{+}{\mathbf{\mu }}^{-}$ on the baryon asymmetry of the Universe

    Elina Fuchs🇮🇱 · Marta Losada🇦🇪 · Yosef Nir🇮🇱 · Yehonatan Viernik🇮🇱

    The upper bounds from the ATLAS and CMS experiments on the decay rate of the Higgs boson to two muons provide the strongest constraint on an imaginary part of the muon Yukawa coupling. This bound is more than an order of magnitude stronger than bounds from $\mathcal{C}\mathcal{P}$-violating observables, specifically the electric dipole moment of the electron. It excludes a scenario $-$ which had been viable prior to these measurements $-$ that a complex muon Yukawa coupling is the dominant source of the baryon asymmetry. Even with this bound, the muon source can still contribute $\mathcal{O}(16\%)$ of the asymmetry.

    hep-phPRL(2020)·13 citations
15. 15*

    Scalar induced resonant sterile neutrino production in the early Universe

    F. Bezrukov🇬🇧 · A. Chudaykin🇷🇺 · D. Gorbunov🇷🇺

    It has been recently suggested \cite{Bezrukov:2017ike,Bezrukov:2018wvd} that a cosmic scalar field can completely change the keV-scale sterile neutrino production in the early Universe. Its effect may, for various parameter choices, either suppress sterile neutrino production and make moderate active-sterile mixing cosmologically acceptable, or increase the production and generate considerable dark matter component out of sterile neutrino with otherwise negligible mixing with SM. In this paper we provide analytic estimates complementing and providing details of the numerical calculations performed in \cite{Bezrukov:2018wvd} in the case of resonant amplification of the sterile neutrino production. We also discuss phenomenological and theoretical issues related to the successful implementation of this idea in fully realistic extensions of the Standard Model of particle physics.

    hep-phastro-ph.COPRD(2020)·9 citations
16. 16*

    White Dwarf Bounds on CHAMPs

    Michael A. Fedderke🇺🇸 · Peter W. Graham🇺🇸 · Surjeet Rajendran🇺🇸

    White dwarfs (WD) effectively act as high-gain amplifiers for relatively small energy deposits within their volume via their supernova instability. In this paper, we consider the ways a galactic abundance of $\mathcal{O}(1)$-charged massive relics (i.e., CHAMPs) could trigger this instability, thereby destroying old WD. The dense central core structure formed inside the WD when heavy CHAMPs sink to its center can trigger a supernova via injection of energy during collapse phases, via direct density-enhanced (pycnonuclear) fusion processes of carbon nuclei dragged into the core by the CHAMPs, or via the formation of a black hole (BH) at the center of the WD. In the latter scenario, Hawking radiation from the BH can ignite the star if the BH forms with a sufficiently small mass; if the BH instead forms at large enough mass, heating of carbon nuclei that accrete onto the BH as it grows in size may be able to achieve the same outcome (with the conservative alternative being simply that the WD is devoured by the BH). The known existence of old WD that have not been destroyed by these mechanisms allows us to improve by many orders of magnitude on the existing CHAMP abundance constraints in the regime of large CHAMP mass, $m_X\sim 10^{11}$-$10^{18}$GeV. Additionally, in certain regions of parameter space, we speculate that this setup could provide a trigger mechanism for the calcium-rich gap transients: a class of anomalous, sub-luminous supernova events that occur far outside of a host galaxy.

    hep-phastro-ph.COastro-ph.HEastro-ph.SRPRD(2020)·22 citations
17. 17*

    Improved Limits on Millicharged Particles Using the ArgoNeuT Experiment at Fermilab

    ArgoNeuT Collaboration: R. Acciarri🇺🇸 · C. Adams🇺🇸 · J. Asaadi🇺🇸 · B. Baller🇺🇸 · T. Bolton🇺🇸 · C. Bromberg🇺🇸 · F. Cavanna🇺🇸 · D. Edmunds🇺🇸 · R. S. Fitzpatrick🇺🇸 · B. Fleming🇺🇸 · R. Harnik🇺🇸 · C. James🇺🇸 and 11 other authors

    A search for millicharged particles, a simple extension of the standard model, has been performed with the ArgoNeuT detector exposed to the Neutrinos at the Main Injector beam at Fermilab. The ArgoNeuT Liquid Argon Time Projection Chamber detector enables a search for millicharged particles through the detection of visible electron recoils. We search for an event signature with two soft hits (MeV-scale energy depositions) aligned with the upstream target. For an exposure of the detector of $1.0$ $\times$ $10^{20}$ protons on target, one candidate event has been observed, compatible with the expected background. This search is sensitive to millicharged particles with charges between $10^{-3}e$ and $10^{-1}e$ and with masses in the range from $0.1$ GeV to $3$ GeV. This measurement provides leading constraints on millicharged particles in this large unexplored parameter space region.

    ↳ hep-exhep-phphysics.ins-detPRL(2020)·139 citations
18. 18*

    Searching for the possible signal of the photon-axionlike particle oscillation in the combined GeV and TeV spectra of supernova remnants

    Zi-Qing Xia🇨🇳 · Yun-Feng Liang🇨🇳 · Lei Feng🇨🇳 · Qiang Yuan🇨🇳 · Yi-Zhong Fan🇨🇳 · Jian Wu🇨🇳

    The conversion between photons and axionlike particles (ALPs) in the Milky Way magnetic field could result in the detectable oscillation phenomena in $\gamma$-ray spectra of Galactic sources. In this work, the GeV (Fermi-LAT) and TeV (MAGIC/VERITAS/H.E.S.S.) data of three bright supernova remnants (SNRs, ie. IC443, W51C and W49B) have been adopted together to search such the oscillation effect. Different from our previous analysis of the sole Fermi-LAT data of IC443, we do not find any reliable signal for the photon-ALP oscillation in the joint broadband spectrum of each SNR. The reason for the inconsistence is that in this work we use the latest revision (P8R3) of Fermi-LAT data, updated diffuse emission templates and the new version of the source catalog (4FGL), which lead to some modification of the GeV spectrum of IC443. Then we set constraints on ALP parameters based on the combined analysis of all the three sources. Though these constraints are somewhat weaker than limits from the CAST experiment and globular clusters, they are supportive of and complementary to these other results.

    ↳ astro-ph.HEhep-phPRD(2019)·30 citations
19. 19*

    The hadronic light-by-light scattering contribution to the muon anomalous magnetic moment from lattice QCD

    Thomas Blum🇺🇸 · Norman Christ🇺🇸 · Masashi Hayakawa🇯🇵 · Taku Izubuchi🇺🇸 · Luchang Jin🇺🇸 · Chulwoo Jung🇺🇸 · Christoph Lehner🇩🇪

    We report the first result for the hadronic light-by-light scattering contribution to the muon anomalous magnetic moment with all errors systematically controlled. Several ensembles using 2+1 flavors of physical mass Möbius domain-wall fermions, generated by the RBC/UKQCD collaborations, are employed to take the continuum and infinite volume limits of finite volume lattice QED+QCD. We find $a_{\mu }^{\mathrm{HLbL}}=7.87(3.06{)}_{\text{stat}}(1.77{)}_{\text{sys}}\times 10^{-10}$. Our value is consistent with previous model results and leaves little room for this notoriously difficult hadronic contribution to explain the difference between the Standard Model and the BNL experiment.

    ↳ hep-lathep-phPRL(2020)·498 citations
20. 20*

    Low-redshift constraints on homogeneous and isotropic universes with torsion

    C. M. J. Marques🇵🇹 · C. J. A. P. Martins🇵🇹

    One of the possible extensions of Einstein's General Theory of Relativity consists in allowing for the presence of spacetime torsion. The form of the underlying torsion tensor can be chosen such that the homogeneity and isotropy of Friedmann-Lemaitre-Robertson-Walker universes is preserved, and it has been recently suggested that such universes may undergo accelerating phases. We use recent low-redshift data, coming from Type Ia Supernova and Hubble parameter measurements, to phenomenologically constrain this class of models under the so-called steady-state torsion assumption of a constant fractional contribution of torsion to the volume expansion. We start by considering models without a cosmological constant (where torsion itself would be expected to yield the current acceleration of the universe) finding, in agreement with other recent works, that these are strongly disfavoured by the data. We then treat these models as one-parameter extensions of $\Lambda$CDM, constraining the relative contribution of torsion to the level of a few percent in appropriate units. Finally, we briefly discuss how these constraints may be improved by forthcoming low-redshift data and check the robustness of our results by studying an alternative to the steady-state torsion parametrization.

    ↳ astro-ph.COgr-qchep-phPhys.Dark Univ.(2020)·16 citations
21. 21*

    Tree-level processes in very special relativity

    R. Bufalo🇧🇷 · T. Cardoso e Bufalo🇧🇷

    In this paper we discuss the Bhabha and Compton scattering for the quantum electrodynamics defined in the framework of very special relativity (VSR). The main aspect of the VSR setting is that it admits different types of interactions appearing in a nonlocal form due to the modified gauge invariance. We explore the richness of these new couplings in the evaluation of the differential cross-section for these tree-level processes. We assess the behavior of the leading VSR Lorentz violation modifications by considering some special limits for the Bhabha and Compton cross-section expressions.

    ↳ hep-thhep-phPRD(2019)·11 citations
22. 22*

    Tetraquark interpolating fields in a lattice QCD investigation of the $D_{s0}^{\ast }(2317)$ meson

    Constantia Alexandrou🇨🇾 · Joshua Berlin🇩🇪 · Jacob Finkenrath🇨🇾 · Theodoros Leontiou🇨🇾 · Marc Wagner🇩🇪

    We investigate the $D_{s0}^{\ast }(2317)$ meson using lattice QCD and considering correlation functions of several $\bar{c}s$ two-quark and $\bar{c}s(\bar{u}u+\bar{d}d)$ four-quark interpolating fields. These interpolating fields generate different structures in color, spin and position space including quark-antiquark pairs, tetraquarks and two-meson scattering states. For our computation we use an ensemble simulated with pion mass $m_{\pi }\approx 0.296\text{GeV}$ and spatial volume of extent $2.90\text{fm}$. We find in addition to the expected spectrum of two-meson scattering states another state around $60\text{MeV}$ below the $DK$ threshold, which we interpret as the $D_{s0}^{\ast }(2317)$ meson. This state couples predominantly to a quark-antiquark interpolating field and only weakly to a $DK$ two-meson interpolating field. The coupling to the tetraquark interpolating fields is essentially zero, rendering a tetraquark interpretation of the $D_{s0}^{\ast }(2317)$ meson rather unlikely. Moreover, we perform a scattering analysis using Lüscher's method and the effective range approximation to determine the $D_{s0}^{\ast }(2317)$ mass for infinite spatial volume. We find this mass $51\text{MeV}$ below the $DK$ threshold, rather close to both our finite volume result and the experimentally observed value.

    ↳ hep-lathep-phPRD(2020)·38 citations
23. 23*

    New Flavor-Kinematics Dualities and Extensions of Nonlinear Sigma Models

    Ian Low🇺🇸 · Zhewei Yin🇺🇸

    Nonlinear sigma model (NLSM) based on the coset $\text{SU}(N)\times \text{SU}(N)/\text{SU}(N)$ exhibits several intriguing features at the leading $\mathcal{O}(p^2)$ in the derivative expansion, such as the flavor-kinematics duality and an extended theory controlling the single and triple soft limits. In both cases the cubic biadjoint scalar theory plays a prominent role. We extend these features in two directions. First we uncover a new extended theory for $\text{SO}(N+1)/\text{SO}(N)$ NLSM at $\mathcal{O}(p^2)$, which is a cubic bifundamental/biadjoint scalar theory. Next we provide evidence for flavor-kinematics dualities up to $\mathcal{O}(p^4)$ for both $\text{SU}(N)$ and $\text{SO}(N)$ NLSM's. In particular, we introduce a new duality building block based on the symmetric tensor ${\delta }^{ab}$ and demonstrate several flavor-kinematics dualities for 4-point amplitudes, which precisely match the soft blocks employed to soft-bootstrap the NLSM's up to $\mathcal{O}(p^4)$.

    ↳ hep-thhep-phnucl-thPLB(2020)·37 citations
24. 24*

    Application of Effective Field Theory in Nuclear Physics

    Xiaojun Yao🇺🇸

    The production of heavy quarkonium in heavy ion collisions has been used as an important probe of the quark-gluon plasma (QGP). Due to the plasma screening effect, the color attraction between the heavy quark antiquark pair inside a quarkonium is significantly suppressed at high temperature and thus no bound states can exist, i.e., they "melt". In addition, a bound heavy quark antiquark pair can dissociate if enough energy is transferred to it in a dynamical process inside the plasma. So one would expect the production of quarkonium to be considerably suppressed in heavy ion collisions. However, experimental measurements have shown that a large amount of quarkonia survive the evolution inside the high temperature plasma. It is realized that the in-medium recombination of unbound heavy quark pairs into quarkonium is as crucial as the melting and dissociation. Thus, phenomenological studies have to account for static screening, dissociation and recombination in a consistent way. But recombination is less understood theoretically than the melting and dissociation. Many studies using semi-classical transport equations model the recombination effect from the consideration of detailed balance at thermal equilibrium. However, these studies cannot explain how the system of quarkonium reaches equilibrium and estimate the time scale of the thermalization. Recently, another approach based on the open quantum system formalism started being used. In this framework, one solves a quantum evolution for in-medium quarkonium. Dissociation and recombination are accounted for consistently. However, the connection between the semi-classical transport equation and the quantum evolution is not clear. In this dissertation, I will try to address the issues raised above. As a warm-up project, I will first study a similar problem: $\alpha$-$\alpha$ scattering at the ${}^8$Be resonance inside an $e^{-}{e}^{+}\gamma$ plasma. By applying pionless effective field theory and thermal field theory, I will show how the plasma screening effect modifies the ${}^8$Be resonance energy and width. I will discuss the need to use the open quantum system formalism when studying the time evolution of a system embedded inside a plasma. Then I will use effective field theory of QCD and the open quantum system formalism to derive a Lindblad equation for bound and unbound heavy quark antiquark pairs inside a weakly-coupled QGP. Under the Markovian approximation and the assumption of weak coupling between the system and the environment, the Lindblad equation will be shown to turn to a Boltzmann transport equation if a Wigner transform is applied to the open system density matrix. These assumptions will be justified by using the separation of scales, which is assumed in the construction of effective field theory. I will show the scattering amplitudes that contribute to the collision terms in the Boltzmann equation are gauge invariant and infrared safe. By coupling the transport equation of quarkonium with those of open heavy flavors and solving them using Monte Carlo simulations, I will demonstrate how the system of bound and unbound heavy quark antiquark pairs reaches detailed balance and equilibrium inside the QGP. Phenomenologically, my calculations can describe the experimental data on bottomonium production. Finally I will extend the framework to study the in-medium evolution of heavy diquarks and estimate the production rate of the doubly charmed baryon ${\Xi }_{cc}^{++}$ in heavy ion collisions.

    ↳ nucl-thhep-phProQuest Number: 13882375 (2019)·3 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.