Wed·May 27, 2020Wednesday·May 27, 2020

1. 01*

   Learning the latent structure of collider events

   Barry M. Dillon🇸🇮 · Darius A. Faroughy🇨🇭 · Jernej F. Kamenik🇸🇮 · Manuel Szewc🇦🇷

   We describe a technique to learn the underlying structure of collider events directly from the data, without having a particular theoretical model in mind. It allows to infer aspects of the theoretical model that may have given rise to this structure, and can be used to cluster or classify the events for analysis purposes. The unsupervised machine-learning technique is based on the probabilistic (Bayesian) generative model of Latent Dirichlet Allocation. We pair the model with an approximate inference algorithm called Variational Inference, which we then use to extract the latent probability distributions describing the learned underlying structure of collider events. We provide a detailed systematic study of the technique using two example scenarios to learn the latent structure of di-jet event samples made up of QCD background events and either $t\bar{t}$ or hypothetical $W^{\prime }\to (\varphi \to WW)W$ signal events.

   hep-phhep-exJHEP(2020)·69 citations
2. 02*

   Light-by-light scattering sum rule for radiative transitions of bottomonia

   Victor Ananyev🇩🇪 · Igor Danilkin🇩🇪 · Marc Vanderhaeghen🇩🇪

   We generalize a forward light-by-light scattering sum rule to the case of heavy quarkonium radiative transitions. We apply such sum rule to the bottomonium states, and use available data on radiative transitions in its evaluation. For the transitions that are not known experimentally, we provide theoretical estimates within a potential model, and consider the spread between similar approaches in the literature as an estimate for the model error. For the ${\rm Y}(1S)$, ${\rm Y}(2S)$, and ${\rm Y}(3S)$ states we observe that, due to a cancellation between transitions involving ${\chi }_{b0},{\chi }_{b1}$, and ${\chi }_{b2}$ states, the sum rule is satisfied within experimental and theoretical error estimates. Having tested this sum rule for the low-lying bottomonium states, it may be used as a tool to investigate the nature of exotic states in the charmonium and bottomonium spectrum through the corresponding radiative transitions.

   hep-phPRD(2020)·3 citations
3. 03*

   Simplified leptoquark models for precision $l_i\to l_f\gamma$ experiments: two-loop structure of $O({\alpha }_S{Y}^2)$ corrections

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

   We put forward the framework of simplified leptoquark models: simple extensions of the Standard Model that serve as benchmarks to test the interactions of leptons with new colored degrees of freedom considered, for instance, in leptoquark or grand unification models. As a first application of the scheme, we analyze the power of precision lepton observables by computing gauge invariant two-loop radiative corrections to the lepton-photon vertex, generated here by Yukawa interactions between the lepton and new colored degrees of freedom. The result, detailed in explicit expressions for the involved form factors, improves on the literature for the higher loop order considered and highlights the existence of regions in the parameter space of the model where two-loop corrections cannot be neglected.

   hep-phPRD(2020)·14 citations
4. 04*

   Interpretation of excited ${\Omega }_b$ signals

   Marek Karliner🇮🇱 · Jonathan L. Rosner🇺🇸

   Recently LHCb reported the discovery of four extremely narrow excited ${\Omega }_b$ baryons decaying into ${\Xi }_b^0{K}^{-}$. We interpret these baryons as bound states of a $b$-quark and a $P$-wave $ss$-diquark. For such a system there are exactly five possible combinations of spin and orbital angular momentum. We predict two of spin 1/2, two of spin 3/2, and one of spin 5/2, all with negative parity. We favor identifying the observed states as those those with spins 1/2 and 3/2, and give a range of predicted masses for the one with spin 5/2. We update earlier predictions for these states based on the five narrow excited ${\Omega }_c$ states reported by LHCb. An alternative picture of the states in which one of $J=1/2$ is extremely wide and hence not seen by LHCb is discussed.

   hep-phPRD(2020)·17 citations
5. 05*

   Using $\bar{p}p$ and $e^{+}{e}^{-}$ Annihilation Data to Refine Bounds on the Baryon-Number-Violating Dinucleon Decays $nn\to e^{+}{e}^{-}$ and $nn\to {\mu }^{+}{\mu }^{-}$

   Shmuel Nussinov🇮🇱 · Robert Shrock🇺🇸

   We use $\bar{p}p$ and $e^{+}{e}^{-}$ annihilation data to further strengthen lower bounds on the partial lifetimes for the baryon-number-violating dinucleon decays $nn\to e^{+}{e}^{-}$ and $nn\to {\mu }^{+}{\mu }^{-}$.

   hep-phhep-exPRD(2020)·11 citations
6. 06*

   Energy dependent chemical potentials of light hadrons and quarks based on transverse momentum spectra and yield ratios of negative to positive particles

   Xing-Wei He🇨🇳 · Feng-Min Wu🇨🇳 · Hua-Rong Wei🇨🇳 · Bi-Hai Hong🇨🇳

   We describe the transverse momentum (or mass) spectra of ${\pi }^{\pm }$, $K^{\pm }$, $p$, and $\bar{p}$ produced in central gold-gold (Au-Au), central lead-lead (Pb-Pb), and inelastic proton-proton ($pp$) collisions at different collision energies range from the AGS to LHC by using a two-component (in most cases) Erlang distribution in the framework of multi-source thermal model. The fitting results are consistent with the experimental data and the energy-dependent chemical potentials of light hadrons ($\pi$, $K$, and $p$) and quarks ($u$, $d$, and $s$) in central Au-Au, central Pb-Pb, and inelastic $pp$ collisions from the yield ratios of negative to positive particles obtained from the normalization constants are then extracted. The study shows that most types of energy-dependent chemical potentials decrease with increase of collision energy over a range from the AGS to LHC. The curves of all types of energy-dependent chemical potentials, obtained from the linear fits of yield ratios vs energy, have inflection points at the same energy of 3.526 GeV, which is regarded as the critical energy of phase transition from a hadron liquid-like state to a quark gas-like state in the collision system and indicates that the hadronic interactions play an important role in this period. At the RHIC and LHC, all types of chemical potentials become small and tend to zero at very high energy, which confirms that the collision system possibly changes completely from the hadron-dominant liquid-like state to the quark-dominant gas-like state and the partonic interactions possibly play a dominant role at the LHC.

   hep-phnucl-thAdv.High Energy Phys.(2020)·5 citations
7. 07*

   Efficacy of scalar leptoquark on $B_s\to (K^{(\ast )},D_s^{(\ast )})\tau {\bar{\nu }}_{\tau }$ decay modes

   Suchismita Sahoo🇮🇳 · Anupama Bhol🇮🇳

   We scrutinize the impact of various relevant scalar leptoquarks on the physical observables associated with the rare semileptonic decay processes of $B_s$ meson involving $b\to (u,c)l{\bar{\nu }}_l$ quark level transitions. We constrain the new parameter space consistent with the experimental limit on Br($B_{u,c}\to \tau {\nu }_l$), Br($B\to \pi \tau {\bar{\nu }}_{\tau }$), $R_{D^{(\ast )}},R_{J/\psi }$ and $R_{\pi }^l$ observables. Using the allowed parameter space, we compute the branching ratios, forward-backward asymmetries, lepton and hardon polarization asymmetries of $B_s\to (K^{(\ast )},D_s^{(\ast )})\tau {\bar{\nu }}_{\tau }$ decay modes. Forbye, we look at the possibility of existence of lepton non-universality in these processes.

   hep-ph9 citations
8. 08*

   Comment on "Comment on "Landau equation and QCD sum rules for the tetraquark molecular states""

   Zhi-Gang Wang🇨🇳

   In "Landau equation and QCD sum rules for the tetraquark molecular states", I list out six reasons to refute the assertion of Lucha, Melikhov and Sazdjian. In "Comment on "Landau equation and QCD sum rules for the tetraquark molecular states"", they refute my viewpoint. If they want to the refute my viewpoint robustly, they should refute the six reasons one by one, and provide at least one example to illustrate that they have obtained reliable QCD sum rules for the tetraquark states and free two-meson states, respectively.

   hep-ph7 citations
9. 09*

   Light and Darkness: consistently coupling dark matter to photons via effective operators

   Chiara Arina🇧🇪 · Andrew Cheek🇧🇪 · Ken Mimasu🇧🇪 · Luca Pagani🇮🇹

   We revise the treatment of fermionic dark matter interacting with photons via dimension-5 and -6 effective operators. We show how the application of the effective operators beyond their validity introduces unphysical, gauge violating effects that are relevant for current experimental searches. Restoring gauge invariance by coupling dark matter to the hypercharge gauge field has implications for the parameter space above and below the electroweak scale. We review the phenomenology of these hypercharge form factors at the LHC as well as for direct and indirect detection experiments. We highlight where the electromagnetic and hypercharge descriptions lead to wildly different conclusions about the viable parameter space and the relative sensitivity of various probes. These include a drastic weakening of vector bosons fusion versus mono-jet searches at the LHC, and the incorrect impression that indirect searches could lead to better constraints than direct detection for larger dark matter masses. We find that the dimension-5 operators are strongly constrained by direct detection bounds, while for dimension-6 operators LHC mono-jet searches are competitive or performing better than the other probes we consider.

   hep-phastro-ph.COEPJC(2021)·46 citations
10. 10*

    Hadronic transport coefficients from the linear sigma model at finite temperature

    Matthew Heffernan🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦

    We investigate general frameworks for calculating transport coefficients for quasiparticle theories at finite temperature. Hadronic transport coefficients are then computed using the linear sigma model (LSM). The bulk viscosity over entropy density ($\zeta /s$) is evaluated in the relaxation time approximation (RTA) and the specific shear viscosity ($\eta /s$) and static electrical conductivity (${\sigma }_{el}/T$) are both obtained in the RTA and using a functional variational approach. Results are shown for different values of the scalar-isoscalar hadron vacuum mass with in-medium masses for the interacting fields. The advantages and limitations of the LSM for studies of strongly interacting matter out of equilibrium are discussed and results are compared with others in the literature.

    hep-phnucl-exnucl-thPRC(2020)·17 citations
11. 11*

    Higgs chameleon

    Rong-Gen Cai🇨🇳 · Shao-Jiang Wang🇺🇸

    The existing constraints from particle colliders reveal a suspicious but nonlethal metastability for our current electroweak vacuum of Higgs potential in the standard model of particle physics, which is, however, disfavored in the early Universe if the inflationary Hubble scale is larger than the instability scale when Higgs quartic self-coupling runs into negative value. Alternative to previous trials of acquiring a positive effective mass-squared from Higgs quadratic couplings to Ricci scalar or inflaton field, we propose a third approach to stabilize the Higgs potential in the early Universe by regarding Higgs as chameleon coupled to inflaton alone without conflicting to the present constraints on either Higgs or chameleon.

    hep-phastro-ph.COgr-qcPRD(2021)·7 citations
12. 12*

    Structure of two-loop SMEFT anomalous dimensions via on-shell methods

    Zvi Bern🇺🇸 · Julio Parra-Martinez🇺🇸 · Eric Sawyer🇺🇸

    We describe on-shell methods for computing one- and two-loop anomalous dimensions in the context of effective field theories containing higher-dimension operators. We also summarize methods for computing one-loop amplitudes, which are used as inputs to the computation of two-loop anomalous dimensions, and we explain how the structure of rational terms and judicious renormalization scheme choices can lead to additional vanishing terms in the anomalous dimension matrix at two loops. We describe the two-loop implications for the Standard Model Effective Field Theory (SMEFT). As a by-product of this analysis we verify a variety of one-loop SMEFT anomalous dimensions computed by Alonso, Jenkins, Manohar and Trott.

    hep-phhep-thJHEP(2020)·111 citations
13. 13*

    General relativistic non-ideal fluid equations for dark matter from a truncated cumulant expansion

    Alaric Erschfeld🇩🇪 · Stefan Floerchinger🇩🇪 · Maximilian Rupprecht🇩🇪

    A new truncation scheme based on the cumulant expansion of the one-particle phase-space distribution function for dark matter particles is developed. Extending the method of moments in relativistic kinetic theory, we derive evolution equations which supplement the covariant conservation of the energy-momentum tensor and particle number current. Truncating the cumulant expansion we obtain a closed, covariant and hyperbolic system of equations which can be used to model the evolution of a general relativistic non-ideal fluid. As a working example we consider a Friedmann-Lemaître-Robertson-Walker cosmology with dynamic pressure and solve for the time evolution of the effective equation of state parameter.

    hep-phastro-ph.COPRD(2020)·7 citations
14. 14*

    Modeling of $t$-channel single top-quark production at the LHC

    Jun Gao🇨🇳 · Edmond L. Berger🇺🇸

    We study the modeling of $t$-channel single top-quark production at Large Hadron Collider (LHC) energies. We compare predictions at next-to-next-to-leading order in a 5-flavor scheme to those of next-to-leading order in a 4-flavor scheme, finding the two schemes agree within a few percent in general for the shape of kinematic distributions of the top quark. The predictions in the 5-flavor scheme show strong stability for both normalization and distributions, and are superior to those of the 4-flavor scheme at comparable orders. We present comparisons of the predictions with LHC data. Our findings provide clear theoretical guidance for precision studies of single top-quark physics at the LHC.

    hep-phPLB(2020)·7 citations
15. 15*

    Origin of sub-TeV afterglow emission from gamma-ray bursts GRB 190114C and GRB 180720B

    Sarira Sahu🇲🇽 · Carlos E. Lopez Fortin🇲🇽

    The detection of GRB 180722B and GRB 190114C in sub-TeV gamma-rays has opened up a new window to study gamma-ray bursts in high energy gamma-rays. Recently it is shown that the synchrotron and inverse Compton processes are responsible for the production of these high energy gamma-rays during the afterglow. Here, for the first time we demonstrate that, the photohadronic scenario which is successful in explaining the multi-TeV flaring in high energy blazars is also applicable for gamma-ray bursts. We show that the sub-TeV spectra of GRB 190114C and GRB 180720B are due to the interaction of high energy protons with the background photons in the synchrotron self-Compton region and synchrotron region respectively. The nature of the background photon distributions help us to constraint their bulk Lorentz factors.

    ↳ astro-ph.HEhep-phApJL(2020)·25 citations
16. 16*

    Dark Energy with Phantom Crossing and the $H_0$ tension

    Eleonora Di Valentino🇬🇧 · Ankan Mukherjee🇮🇳 · Anjan A. Sen🇮🇳

    We investigate the possibility of phantom crossing in the dark energy sector and solution for the Hubble tension between early and late universe observations. We use robust combinations of different cosmological observations, namely the CMB, local measurement of Hubble constant ($H_0$), BAO and SnIa for this purpose. For a combination of CMB+BAO data which is related to early Universe physics, phantom crossing in the dark energy sector is confirmed at $95$\% confidence level and we obtain the constraint $H_0=71.0_{-3.8}^{+2.9}$ km/s/Mpc at 68\% confidence level which is in perfect agreement with the local measurement by Riess et al. We show that constraints from different combination of data are consistent with each other and all of them are consistent with phantom crossing in the dark energy sector. For the combination of all data considered, we obtain the constraint $H_0=70.25\pm 0.78$ km/s/Mpc at 68\% confidence level and the phantom crossing happening at the scale factor $a_m=0.851_{-0.031}^{+0.048}$ at 68\% confidence level.

    ↳ astro-ph.COhep-phEntropy(2021)·216 citations
17. 17*

    Cosmological constraints from HII starburst galaxy apparent magnitude and other cosmological measurements

    Shulei Cao🇺🇸 · Joseph Ryan🇺🇸 · Bharat Ratra🇺🇸

    We use HII starburst galaxy apparent magnitude measurements to constrain cosmological parameters in six cosmological models. A joint analysis of HII galaxy, quasar angular size, baryon acoustic oscillations peak length scale, and Hubble parameter measurements result in relatively model-independent and restrictive estimates of the current values of the non-relativistic matter density parameter ${\Omega }_{{\mathrm{m}}_0}$ and the Hubble constant $H_0$. These estimates favor a 2.0$\sigma$ to 3.4$\sigma$ (depending on cosmological model) lower $H_0$ than what is measured from the local expansion rate. The combined data are consistent with dark energy being a cosmological constant and with flat spatial hypersurfaces, but do not strongly rule out mild dark energy dynamics or slightly non-flat spatial geometries.

    ↳ astro-ph.COgr-qchep-phhep-thMNRAS(2020)·73 citations
18. 18*

    Revisiting modular symmetry in magnetized torus and orbifold compactifications

    Shota Kikuchi🇯🇵 · Tatsuo Kobayashi🇯🇵 · Shintaro Takada🇯🇵 · Takuya H. Tatsuishi🇯🇵 · Hikaru Uchida🇯🇵

    We study the modular symmetry in $T^2$ and orbifold comfactifications with magnetic fluxes. There are $|M|$ zero-modes on $T^2$ with the magnetic flux $M$. Their wavefunctions as well as massive modes behave as modular forms of weight $1/2$ and represent the double covering group of $\Gamma \equiv SL(2,\mathbb{Z})$, $\tilde{\Gamma }\equiv \widetilde{SL}(2,\mathbb{Z})$. Each wavefunction on $T^2$ with the magnetic flux $M$ transforms under $\tilde{\Gamma }(2|M|)$, which is the normal subgroup of $\widetilde{SL}(2,\mathbb{Z})$. Then, $|M|$ zero-modes are representations of the quotient group ${\tilde{\Gamma }}_{2|M|}^{\prime }\equiv \tilde{\Gamma }/\tilde{\Gamma }(2|M|)$. We also study the modular symmetry on twisted and shifted orbifolds $T^2/{\mathbb{Z}}_N$. Wavefunctions are decomposed into smaller representations by eigenvalues of twist and shift. They provide us with reduction of reducible representations on $T^2$.

    ↳ hep-thhep-phmath.NTPRD(2020)·102 citations
19. 19*

    On catalyzed vacuum decay around a radiating black hole and the crisis of the electroweak vacuum

    Takumi Hayashi🇯🇵 · Kohei Kamada🇯🇵 · Naritaka Oshita🇨🇦 · Jun'ichi Yokoyama🇯🇵

    False vacuum decay is a key feature in quantum field theories and exhibits a distinct signature in the early Universe cosmology. It has recently been suggested that the false vacuum decay is catalyzed by a black hole (BH), which might cause the catastrophe of the Standard Model Higgs vacuum if primordial BHs are formed in the early Universe. We investigate vacuum phase transition of a scalar field around a radiating BH with taking into account the effect of Hawking radiation. We find that the vacuum decay rate slightly decreases in the presence of the thermal effect since the scalar potential is stabilized near the horizon. However, the stabilization effect becomes weak at the points sufficiently far from the horizon. Consequently, we find that the decay rate is not significantly changed unless the effective coupling constant of the scalar field to the radiation is extremely large. This implies that the change of the potential from the Hawking radiation does not help prevent the Standard Model Higgs vacuum decay catalyzed by a BH.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2020)·41 citations
20. 20*

    New de Sitter solutions of 10d type IIB supergravity

    David Andriot🇦🇹 · Paul Marconnet🇫🇷 · Timm Wrase🇦🇹

    We find and study 17 new de Sitter solutions of ten-dimensional (10d) type IIB supergravity with intersecting D5-branes and orientifold O5-planes, as well as a new Minkowski one. These solutions are obtained numerically on 6d group manifolds, the compactness of which is established for 4 of them. We show that all our de Sitter solutions are perturbatively unstable, using a restricted 4d effective theory of four scalar fields. We finally analyse whether our solutions can be promoted to classical string backgrounds. Several of them appear as good candidates, as they satisfy all requirements imposed so far.

    ↳ hep-thgr-qchep-phJHEP(2020)·50 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.