Fri·May 7, 2021Friday·May 7, 2021

1. 01*

   Hidden charm tetraquark states in a diquark model

   Pan-Pan Shi🇨🇳 · Fei Huang🇨🇳 · Wen-Ling Wang🇨🇳

   The purpose of the present study is to explore the mass spectrum of the hidden charm tetraquark states within a diquark model. Proposing that a tetraquark state is composed of a diquark and an antidiquark, the masses of all possible $[qc][\bar{q}\bar{c}]$, $[sc][\bar{s}\bar{c}]$, and $[qc][\bar{s}\bar{c}]$ $\left([sc][\bar{q}\bar{c}]\right)$ hidden charm tetraquark states are systematically calculated by use of an effective Hamiltonian, which contains color, spin, and flavor dependent interactions. Apart from the $X(3872)$, $Z(3900)$, ${\chi }_{c2}(3930)$, and $X(4350)$ which are taken as input to fix the model parameters, the calculated results support that the ${\chi }_{c0}(3860)$, $X(4020)$, $X(4050)$ are $[qc][\bar{q}\bar{c}]$ states with $I^G{J}^{PC}=0^{+}{0}^{++}$, $1^{+}{1}^{+-}$, and $1^{-}{2}^{++}$, respectively, the ${\chi }_{c1}(4274)$ is an $[sc][\bar{s}\bar{c}]$ state with $I^G{J}^{PC}=0^{+}{1}^{++}$, the $X(3940)$ is a $[qc][\bar{q}\bar{c}]$ state with $I^G{J}^{PC}=1^{-}{0}^{++}$ or $1^{-}{1}^{++}$, the $Z_{cs}(3985{)}^{-}$ is an $[sc][\bar{q}\bar{c}]$ state with $J^P=0^{+}$ or $1^{+}$, and the $Z_{cs}(4000{)}^{+}$ and $Z_{cs}(4220{)}^{+}$ are $[qc][\bar{s}\bar{c}]$ states with $J^P=1^{+}$. Predictions for other possible tetraquark states are also given.

   hep-phnucl-thPRD(2021)·56 citations
2. 02*

   Same-Sign Tetralepton Signature in Type-II Seesaw at Lepton Colliders

   Xu-Hong Bai🇺🇸 · Zhi-Long Han🇨🇳 · Yi Jin🇨🇳 · Hong-Lei Li🇨🇳 · Zhao-Xia Meng🇨🇳

   The same-sign tetralepton signature via mixing of neutral Higgs bosons and their cascade decays to charged Higgs bosons is a unique signal in the type-II seesaw model. In this paper, we study this signature at future lepton colliders, such as ILC, CLIC, and MuC. Constrained by direct search, $H^{\pm \pm }\to W^{\pm }{W}^{\pm }$ is the only viable decay mode for $M_{A^0}=400$ GeV at $\sqrt{s}=1$ TeV ILC. With an integrated luminosity of $\mathcal{L}=8{\mathrm{ab}}^{-1}$, the promising region with about 150 signal events corresponds to a narrow band in the range of $10^{-4}\text{GeV}\lesssim v_{\Delta }\lesssim 10^{-2}$ GeV. For heavier triplet scalars $M_{A^0}\gtrsim 900$ GeV, although the $H^{\pm \pm }\to {\ell }^{\pm }{\ell }^{\pm }$ decay mode is allowed, the cascade decays are suppressed. A maximum event number $\sim 16$ can be obtained around $v_{\Delta }\sim 4\times 10^{-4}$ GeV and ${\lambda }_4\sim 0.26$ for $M_{A^0}=1000$ GeV with $\mathcal{L}=5{\mathrm{ab}}^{-1}$ at $\sqrt{s}=3$ TeV CLIC. Meanwhile, we find that this signature is not promising for $M_{A^0}=1500$ GeV at $\sqrt{s}=6$ TeV MuC.

   hep-phhep-exCPC(2022)·10 citations
3. 03*

   Fully-heavy tetraquarks and other heavy multiquarks

   Jean-Marc Richard🇫🇷

   A review is presented of some discussions about the fully-heavy tetraquarks made of two charmed quarks and two anticharmed antiquarks, and other multiquark states involving some heavy flavors.

   hep-phNucl.Part.Phys.Proc.(2021)·7 citations
4. 04*

   Gamma production in neutrino interaction with nuclei

   Guy Chanfray🇫🇷 · Magda Ericson🇫🇷

   We evaluate the cross-section for gamma production by neutrinos through a meson exchange effect which derives from the concept of axial-vector mixing. The resulting cross-section leads to some increase of the gamma production cross-section by neutrinos, especially at low neutrino energies, which may influence the understanding of the low energy excess of electron-like events seen in the MiniBooNE experiment.

   hep-phnucl-thPRC(2021)·6 citations
5. 05*

   Leptophilic U(1) Massive Vector Bosons from Large Extra Dimensions

   Luis A. Anchordoqui🇺🇸 · Ignatios Antoniadis🇫🇷 · Xing Huang🇨🇳 · Dieter Lust🇩🇪 · Tomasz R. Taylor🇺🇸

   We demonstrate that the discrepancy between the anomalous magnetic moment measured at BNL and Fermilab and the Standard Model prediction could be explained within the context of low-scale gravity and large extra-dimensions. The dominant contribution to $(g-2{)}_{\mu }$ originates in Kaluza-Klein (KK) excitations (of the lepton gauge boson) which do not mix with quarks (to lowest order) and therefore can be quite light avoiding LHC constraints. We show that the KK contribution to $(g-2{)}_{\mu }$ is universal with the string scale entering as an effective cutoff. The KK tower provides a unequivocal distinctive signal which will be within reach of the future muon smasher.

   hep-phhep-thPLB(2021)·10 citations
6. 06*

   Light scalaron as dark matter

   Yuri Shtanov🇺🇦

   A new cosmological scenario is proposed in which a light scalaron of $f(R)$ gravity plays the role of dark matter. In this scenario, the scalaron initially resides at the minimum of its effective potential while the electroweak symmetry is unbroken. At the beginning of the electroweak crossover, the evolving expectation value of the Higgs field triggers the evolution of the scalaron due to interaction between these fields. After the electroweak crossover, the oscillating scalaron can represent cold dark matter. Its current energy density depends on a single free parameter, the scalaron mass $m$, and the value $m\simeq 4\times 10^{-3}\text{eV}$ is required to explain the observed dark-matter abundance. Larger mass values would be required in scenarios where the scalaron is excited before the electroweak crossover.

   hep-phastro-ph.COgr-qcPLB(2021)·26 citations
7. 07*

   Probing $D_{s0}^{\ast }(2317)$ in the decays of $B$ to two charmed mesons

   Zhi-Qing Zhang🇨🇳 · Meng-Ge Wang🇨🇳 · Yan-Chao Zhao🇨🇳 · Zhi-Lin Guan🇨🇳 · Na Wang🇨🇳

   We probe the inner structure of the meson $D_{s0}^{\ast }(2317)$ through the decays of $B_{(s)}$ to two charmed mesons within pQCD approach. Assuming $D_{s0}^{\ast }(2317)$ as a scalar meson with $\bar{c}s$ structure, we find that the predictions for the branching ratios of the decays $B^{+}\to D_{s0}^{\ast +}(2317){\bar{D}}^{(\ast )0},B^0\to D_{s0}^{\ast +}(2317)D^{(\ast )-}$ can explain data within errors. The branching ratios for the decays $B_s\to D_{s0}^{\ast +}(2317)D_s^{(\ast )+}$ are estimated to reach up to $10^{-3}$ order, which can be observed by the present LHCb and SuperKEKB experiments. In this work, the decay constant of the meson $D_{s0}^{\ast }(2317)$ is an input parameter. Unfortunately, its value has been studied by many references but with large uncertainties. Our calculation shows that a smaller decay constant of the meson $D_{s0}^{\ast }(2317)$ is supported by compared with the present data, say $55\sim 70$ MeV. We also calculate the ratios $R_1=\frac{Br(B^{+}\to D_{s0}^{\ast +}(2317){\bar{D}}^0)}{Br(B^{+}\to D_{s0}^{\ast +}(2317){\bar{D}}^{\ast 0})})$ and $R_2=\frac{Br(B^0\to D_{s0}^{\ast +}(2317)D^{-})}{Br(B^0\to D_{s0}^{\ast +}(2317)D^{\ast -})}$, which are valuable to determine the inner structure of $D_{s0}^{\ast }(2317)$ by compared with the experimental results. Our predictions for the ratios $R_{1,2}$ are consistent with the present data within errors.We expect that these two ratios can be well measured by the future experiments through improving the measurement accuracy for the decays $B^{+}\to D_{s0}^{\ast +}(2317){\bar{D}}^{\ast 0}$ and $B^0\to D_{s0}^{\ast +}(2317)D^{\ast -}$.

   hep-phhep-exPRD(2021)·3 citations
8. 08*

   Two-loop corrections to the Higgs trilinear coupling in BSM models with classical scale invariance

   Johannes Braathen🇩🇪 · Shinya Kanemura🇯🇵 · Makoto Shimoda🇯🇵

   Classical scale invariance (CSI) is an attractive concept for BSM model building, explaining the apparent alignment of the Higgs sector and potentially relating to the hierarchy problem. Furthermore, a particularly interesting feature is that the Higgs trilinear coupling ${\lambda }_{hhh}$ is universally predicted at one loop in CSI models, and deviates by 67% from its (tree-level) SM prediction. This result is however modified at two loops, and we review in these proceedings our calculation of leading two-loop corrections to ${\lambda }_{hhh}$ in models with classical scale invariance, taking as an example a CSI scenario of a Two-Higgs-Doublet Model. We find that the inclusion of two-loop effects allows distinguishing different scenarios with CSI, although the requirement of reproducing the known 125-GeV Higgs-boson mass severely restricts the allowed values of ${\lambda }_{hhh}$.

   hep-ph0 citations
9. 09*

   On the decomposition theorem for gluons

   I.V. Anikin🇷🇺 · A.S. Zhevlakov🇷🇺

   Recently, the problem of spin and orbital angular momentum (AM) separation has widely been discussed. Nowadays, all discussions about the possibility to separate the spin AM from the orbital AM in the gauge invariant manner are based on the ansatz that the gluon field can be presented in form of the decomposition where the physical gluon components are additive to the pure gauge gluon components, i.e. $A_{\mu }=A_{\mu }^{\text{phys}}+A_{\mu }^{\text{pure}}$. In the present paper, we show that in the non-Abelian gauge theory this gluon decomposition has a strong mathematical evidence in the frame of the contour gauge conception. In other words, we reformulate the gluon decomposition ansatz as a theorem on decomposition and, then, we use the contour gauge to prove this theorem. In the first time, we also demonstrate that the contour gauge possesses the special kind of residual gauge related to the boundary field configurations and expressed in terms of the pure gauge fields. As a result, the trivial boundary conditions lead to the inference that the decomposition includes the physical gluon configurations only provided the contour gauge condition.

   hep-phJ.Exp.Theor.Phys.(2022)·4 citations
10. 10*

    Dark Matter as dark dwarfs and other macroscopic objects: multiverse relics?

    Christian Gross🇮🇹 · Giacomo Landini🇮🇹 · Alessandro Strumia🇮🇹 · Daniele Teresi🇨🇭

    First-order phase transitions can leave relic pockets of false vacua and their particles, that manifest as macroscopic Dark Matter. We compute one predictive model: a gauge theory with a dark quark relic heavier than the confinement scale. During the first-order phase transition to confinement, dark quarks remain in the false vacuum and get compressed, forming Fermi balls that can undergo gravitational collapse to stable dark dwarfs (bound states analogous to white dwarfs) near the Chandrasekhar limit, or to primordial black holes.

    hep-phastro-ph.COhep-thJHEP(2021)·105 citations
11. 11*

    Updated Standard Model Prediction for $K\to \pi \nu \bar{\nu }$ and ${ϵ}_K$

    Joachim Brod🇺🇸 · Martin Gorbahn🇬🇧 · Emmanuel Stamou🇩🇪

    The rare $K\to \pi \nu \bar{\nu }$ decay modes and the parameter ${ϵ}_K$ that measures CP violation in Kaon mixing are sensitive probes of physics beyond the standard model. In this article we provide the updated standard-model prediction for the rare decay modes in detail, and summarise the status of standard-model prediction of ${ϵ}_K$. We find $\text{BR}(K^{+}\to {\pi }^{+}\nu \bar{\nu })=7.73(61)\times 10^{-11}$ and $\text{BR}(K_L\to {\pi }^0\nu \bar{\nu })=2.59(29)\times 10^{-11}$. The uncertainties are dominated by parametric input.

    hep-phhep-exPoS(2021)·78 citations
12. 12*

    Violation of energy conditions and entropy production in holographic Bjorken flow

    Romulo Rougemont🇧🇷 · Jorge Noronha🇺🇸 · Willians Barreto🇧🇷 · Gabriel S. Denicol🇧🇷 · Travis Dore🇺🇸

    We demonstrate that a Bjorken expanding strongly coupled $\mathcal{N}=4$ Supersymmetric Yang-Mills plasma can display dynamically-driven violations of the dominant and also the weak energy condition during hydrodynamization. In addition, we find that a period of vanishing entropy production in far-from-equilibrium stages induces later violations of the dominant energy condition in the strongly coupled plasma. Such violations cannot occur in a classical description of hydrodynamization and suggest that the inclusion of quantum effects in transport can lead to new phenomena in these regimes, even for systems without anomalies or spin.

    ↳ nucl-thhep-phhep-thPRD(2021)·16 citations
13. 13*

    Unitarity Bounds for Semileptonic Decays in Lattice QCD

    M. Di Carlo🇬🇧 · G. Martinelli🇮🇹 · M. Naviglio🇮🇹 · F. Sanfilippo🇮🇹 · S. Simula🇮🇹 · L. Vittorio🇮🇹

    In this work we discuss in detail the non-perturbative determination of the momentum dependence of the form factors entering in semileptonic decays using unitarity and analyticity constraints. The method contains several new elements with respect to previous proposals and allows to extract, using suitable two-point functions computed non-perturbatively, the form factors at low momentum transfer $q^2$ from those computed explicitly on the lattice at large $q^2$, without any assumption about their $q^2$-dependence. The approach will be very useful for exclusive semileptonic $B$-meson decays, where the direct calculation of the form factors at low $q^2$ is particularly difficult due to large statistical fluctuations and discretisation effects. As a testing ground we apply our approach to the semileptonic $D\to K\ell {\nu }_{\ell }$ decay, where we can compare the results of the unitarity approach to the explicit direct lattice calculation of the form factors in the full $q^2$-range. We show that the method is very effective and that it allows to compute the form factors with rather good precision.

    ↳ hep-lathep-exhep-phPRD(2021)·63 citations
14. 14*

    Inflationary physics and transplanckian conjecture in the Stringy Running-Vacuum-Model: from the phantom vacuum to the true vacuum

    Nick E. Mavromatos🇬🇧 · Joan Sola🇪🇸

    In previous works we have embedded the Running Vacuum Model (RVM) of Cosmology in the framework of string theory. Specifically, we considered a string-inspired Cosmology with primordial gravitational waves (GW) and gravitational anomalies, which were argued to lead, via appropriate condensation during the very-early-universe era, to dynamical inflation, of RVM type, without the need for extra inflaton fields. A crucial role for the associated slow-roll nature of the inflationary era was played by the fundamental axion field that exists in the gravitational multiplet of strings, viz. the Kalb-Ramond (KR) axion. In this paper, we study further this model and demonstrate several novel facts, completing our previous studies. We clarify the different roles played by the background KR axions, which constitute a form of stiff matter that dominates a pre-RVM-inflationary epoch of the Universe. We show that the KR axion when combined with the gravitational Chern-Simons contribution obey together a peculiar equation of state $p=-\rho$, with negative energy density $\rho <0$, which we call `phantom vacuum'. Eventually, this state transmutes into the standard vacuum state thanks to the contribution from the gravitational Chern-Simons condensate, which makes the total ${\rho }_{\mathrm{total}}=-p_{\mathrm{total}}>0$. At this point the RVM vacuum picture emerges naturally, with an overall equation of state of true vacuum type. We find that our scenario is consistent with the trans-Planckian censorship hypothesis, given that the rate of change of the KR axion takes only sub-Planckian values. We also discuss some explicit scenarios on the creation of GWs within the context of supergravity models that could be embedded in our string theory framework. {Finally, we argue how the RVM in our context can help to alleviate the current tensions of the $\Lambda$CDM.}

    ↳ hep-thgr-qchep-phEur.Phys.J.Plus(2021)·65 citations
15. 15*

    Constraining the dark-energy equation of state with cosmological data

    Yu-Ping Teng🇹🇼 · Wolung Lee🇹🇼 · Kin-Wang Ng🇹🇼

    Recently, the observed equation of state for dark energy appears to favor values below $-1$. The tendency implies that the nature of dark energy may be quite different from that of the cosmological constant. In view of the adjustment on the equation of state keeps decreasing, the introduction of the phantom energy seems inevitable. By employing observational constraints from supernovae and from the acoustic scale in which the accuracy of the data has become extraordinary, we apply a phenomenological scenario to be acquainted with the evolution of our universe. The demonstration on the constrained unfolding of the phantom energy shows the model has high consistency with the current observation.

    ↳ astro-ph.COhep-phPRD(2021)·35 citations
16. 16*

    Analytical derivatives of Neural Networks

    Simone Rodini🇮🇹

    We propose a simple recursive algorithm that allows the computation of the first- and second-order derivatives with respect to the inputs of an arbitrary deep feed forward neural network (DFNN). The algorithm naturally incorporates the derivatives with respect to the network parameters. To test the algorithm, we apply it to the study of the quantum mechanical variational problem for few cases of simple potentials, modeling the ground-state wave function in terms of a DFNN.

    ↳ physics.comp-phhep-phComput.Phys.Commun.(2022)·1 citation
17. 17*

    Relativistic runaway electron avalanches within complex thunderstorm electric field structures

    E. Stadnichuk🇷🇺 · E. Svechnikova🇷🇺 · A. Nozik🇷🇺 · D. Zemlianskaya🇷🇺 · T. Khamitov🇷🇺 · M. Zelenyy🇷🇺 · M. Dolgonosov🇷🇺

    Relativistic runaway electron avalanches (RREAs) are generally accepted as a source of thunderstorms gamma-ray radiation. Avalanches can multiply in the electric field via the relativistic feedback mechanism based on processes with gamma-rays and positrons. This paper shows that a non-uniform electric field geometry can lead to the new RREAs multiplication mechanism - "reactor feedback", due to the exchange of high-energy particles between different accelerating regions within a thundercloud. A new method for the numerical simulation of RREA dynamics within heterogeneous electric field structures is proposed. The developed analytical description and the numerical simulation enables us to derive necessary conditions for TGF occurrence in the system with the reactor feedback Observable properties of TGFs influenced by the proposed mechanism are discussed.

    ↳ physics.ao-phhep-phphysics.geo-phJ.Geophys.Res.Atmos.(2021)·1 citation
18. 18*

    Cosmological perturbations without the Boltzmann hierarchy

    Marc Kamionkowski🇺🇸

    Calculations of the evolution of cosmological perturbations generally involve solution of a large number of coupled differential equations to describe the evolution of the multipole moments of the distribution of photon intensities and polarization. However, this "Boltzmann hierarchy" communicates with the rest of the system of equations for the other perturbation variables only through the photon-intensity quadrupole moment. Here I develop an alternative formulation wherein this photon-intensity quadrupole is obtained via solution of two coupled integral equations -- one for the intensity quadrupole and another for the linear-polarization quadrupole -- rather than the full Boltzmann hierarchy. This alternative method of calculation provides some physical insight and a cross-check for the traditional approach. I describe a simple and efficient iterative numerical solution that converges fairly quickly. I surmise that this may allow current state-of-the-art cosmological-perturbation codes to be accelerated.

    ↳ astro-ph.COgr-qchep-phPRD(2021)·11 citations
19. 19*

    Moduli Stabilisation and the Statistics of Axion Physics in the Landscape

    Igor Broeckel🇮🇹 · Michele Cicoli🇮🇹 · Anshuman Maharana🇮🇳 · Kajal Singh🇮🇳 · Kuver Sinha🇺🇸

    String theory realisations of the QCD axion are often said to belong to the anthropic window where the decay constant is around the GUT scale and the initial misalignment angle has to be tuned close to zero. In this paper we revisit this statement by studying the statistics of axion physics in the string landscape. We take moduli stabilisation properly into account since the stabilisation of the saxions is crucial to determine the physical properties of the corresponding axionic partners. We focus on the model-independent case of closed string axions in type IIB flux compactifications and find that their decay constants and mass spectrum feature a logarithmic, instead of a power-law, distribution. In the regime where the effective field theory is under control, most of these closed string axions are ultra-light axion-like particles, while axions associated to blow-up modes can naturally play the role of the QCD axion. Hence, the number of type IIB flux vacua with a closed string QCD axion with an intermediate scale decay constant and a natural value of the misalignment angle is only logarithmically suppressed. In a recent paper we found that this correlates also with a logarithmic distribution of the supersymmetry breaking scale, providing the intriguing indication that most, if not all, of the phenomenologically interesting quantities in the string landscape might feature a logarithmic distribution.

    ↳ hep-thhep-phJHEP(2022)·64 citations
20. 20*

    The Ubiquity of Gauged Q-Shells

    Julian Heeck🇺🇸 · Arvind Rajaraman🇺🇸 · Christopher B. Verhaaren🇺🇸

    Non-topological gauged soliton solutions called Q-balls arise in many scalar field theories that are invariant under a U(1) gauge symmetry. The related, but qualitatively distinct, Q-shell solitons have only been shown to exist for special potentials. We investigate gauged solitons in a generic sixth-order polynomial potential (that contains the leading effects of many effective field theories) and show that this potential generically allows for both Q-balls and Q-shells. We argue that Q-shell solutions occur in many, and perhaps all, potentials that have previously only been shown to contain Q-balls. We give simple analytic characterizations of these Q-shell solutions, leading to excellent predictions of their physical properties.

    ↳ hep-thhep-phPRD(2021)·13 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.