Thu·Mar 12, 2020Thursday·March 12, 2020

1. 01*

   Dark matter as a heavy thermal hot relic

   Thomas Hambye🇧🇪 · Matteo Lucca🇧🇪 · Laurent Vanderheyden🇧🇪

   If, during the early Universe epoch, the dark matter particle thermalizes in a hidden sector which does not thermalize with the Standard Model thermal bath, its relativistic thermal decoupling can easily lead to the observed relic density, even if the dark matter particle mass is many orders of magnitude heavier than the usual $\sim$ eV hot relic mass scale. This straightforward scenario simply requires that the temperature of the hidden sector thermal bath is one to five orders of magnitude cooler than the temperature of the Standard Model thermal bath. In this way the resulting relic density turns out to be determined only by the dark matter mass scale and the ratio of the temperatures of both sectors. In a model independent way we determine that this can work for a dark matter mass all the way from $\sim 1$ keV to $\sim 30$ PeV. We also show how this scenario works explicitly in the framework of two illustrative models. One of them can lead to a PeV neutrino flux from dark matter decay of the order of the one needed to account for the high energy neutrinos observed by IceCube.

   hep-phPLB(2020)·32 citations
2. 02*

   Investigating entanglement entropy at small-x in DIS off protons and nuclei

   G.S. Ramos🇧🇷 · M.V.T. Machado🇧🇷

   In this work we analyse the entanglement entropy in deep inelastic scattering off protons and nuclei. It is computed based on the formalism where the partonic state at small-x is maximally entangled with proton being constituted by large number of microstates occuring with equal probabilities. We consider analytical expressions for the number of gluons, N_{gluon}, obtained from gluon saturation models for the dipole-target amplitudes within the QCD color dipole picture. In particular, the nuclear entanglement entropy per nucleon is studied. We also study the underlying uncertainties on these calculations and compare the results to similar investigations in literature.

   hep-phquant-phPRD(2020)·37 citations
3. 03*

   The 3.5 keV line from non-perturbative Standard Model dark matter balls

   Colin D. Froggatt🇬🇧 · Holger B. Nielsen🇩🇰

   Our earlier put forward model of dark matter, consisting of cm-size pearls with ordinary matter inside under high pressure and with a mass of order $1.4\ast 10^8$ kg, is used to explain the mysterious 3.5 keV X-ray line from the galactic center and various galaxies and galaxy clusters. The pearls are bubbles of a new type of vacuum and thus surrounded by a surface tension providing the high pressure. We have two rather successful order of magnitude numerical results: 1) the X-ray energy of 3.5 keV comes out as the homolumo-gap or rather as the energy due to screening of electrons in the high pressure ordinary matter inside the pearls, and is well fitted. %predicted correctly to within a factor %{\bf tbc 2} %3; %$40\%$; 2) Using the fitting of Cline and Frey for dark matter radiation arising from collisions or annihilations of dark matter particles we fit the overall intensity of the radiation in our pearl model. We find that a pearl of the minimal size required just by stability, as used in our previous work \cite{Tunguska}, is inconsistent with the observed frequency and intensity of the 3.5 keV line. However the predictions of our model are very sensitive to the radius of the pearls and an excellent fit to both experimental quantities is obtained for a pearl of radius of 2.8 cm.

   hep-ph12 citations
4. 04*

   Towards the understanding of fully-heavy tetraquark states from various models

   Chengrong Deng🇨🇳 · Hong Chen🇨🇳 · Jialun Ping🇨🇳

   We use a color-magnetic interaction model (CMIM), a traditional constituent quark model (CQM) and a multiquark color flux-tube model (MCFTM) to systematically investigate the properties of the states $[Q_1{Q}_2][{\bar{Q}}_3{\bar{Q}}_4]$ ($Q=c,b$). The dynamical investigation indicates that the CMIM can not completely absorb QCD dynamical effects through the effective constituent quark mass and overestimates the color-magnetic interaction in the states under the assumption of the same spatial configurations. The Coulomb interaction plays a critical role in the dynamical model calculations on the heavy hadrons, which induces the fact that none of bound states $[Q_1{Q}_2][{\bar{Q}}_3{\bar{Q}}_4]$ can be found in the dynamical models. The color configuration ${\left[[Q_1{Q}_2{]}_{6_c}[{\bar{Q}}_3{\bar{Q}}_4{]}_{{\bar{6}}_c}\right]}_1$ should be taken seriously in the ground states due to the strong Coulomb attraction between the $[Q_1{Q}_2{]}_{6_c}$ and $[{\bar{Q}}_3{\bar{Q}}_4{]}_{{\bar{6}}_c}$. The color configuration ${\left[[Q_1{Q}_2{]}_{{\bar{3}}_c}[{\bar{Q}}_2{\bar{Q}}_4{]}_{3_c}\right]}_1$ is absolutely dominant in the excited states because of the strong Coulomb attraction within the $[Q_1{Q}_2{]}_{{\bar{3}}_c}$ and $[{\bar{Q}}_2{\bar{Q}}_4{]}_{3_c}$. The $J/\Psi$-pair resonances recently observed by LHCb are difficult to be accommodated in the CMIM. The broad structure ranging from 6.2 to 6.8 GeV can be described as the ground tetraquark state $[cc][\bar{c}\bar{c}]$ in the various dynamical models. The narrow structure $X(6900)$ can be identified as the excited state $[cc][\bar{c}\bar{c}]$ with $L=1$ ($L=2$) in the CQM (MCFTM).

   hep-phPRD(2021)·108 citations
5. 05*

   Doubly Charmed Pentaquarks

   Gang Yang🇨🇳 · Jialun Ping🇨🇳 · Jorge Segovia🇪🇸

   The LHCb Collaboration, using its full data set from runs $1$ and $2$, announced in $2019$ a surprising update of the hidden-charm pentaquark states $P_c(4380{)}^{+}$ and $P_c(4450{)}^{+}$, observed in 2015. A new state, $P_c(4312{)}^{+}$, was clearly seen at lower energies; furthermore, the original $P_c(4450)$ resonance was resolved into two individual states, named the $P_c(4440{)}^{+}$ and the $P_c(4457{)}^{+}$. Motivated by the fact that these new hidden-charm pentaquark states were successfully predicted by our chiral quark model, we extend herein such study to the doubly charmed sector. The analyzed total spin and parity quantum numbers are $J^P={\frac{1}{2}}^{-}$, ${\frac{3}{2}}^{-}$ and ${\frac{5}{2}}^{-}$, in the $I=\frac{1}{2}$ and $\frac{3}{2}$ isospin channels. We find several possible narrow baryon-meson resonances (theoretical masses in parenthesis): $I{J}^P=\frac{1}{2}{\frac{1}{2}}^{-}$ ${\Sigma }_{c}D(4356)$, $\frac{1}{2}{\frac{3}{2}}^{-}$ ${\Sigma }_c^{\ast }D(4449)$, $\frac{3}{2}{\frac{1}{2}}^{-}$ ${\Sigma }_{c}D(4431)$, $\frac{3}{2}{\frac{1}{2}}^{-}$ ${\Sigma }_{c}D(4446)$, $\frac{3}{2}{\frac{3}{2}}^{-}$ ${\Sigma }_c{D}^{\ast }(4514)$ and $\frac{3}{2}{\frac{5}{2}}^{-}$ ${\Xi }_{cc}^{\ast }\rho (4461)$ whose widths are $4.8$, $8.0$, $2.6$, $2.2$, $4.0$ and $3.0\text{MeV}$, respectively. Moreover, one shallow bound-state is found, too, with quantum numbers $I{J}^P=\frac{1}{2}{\frac{3}{2}}^{-}$ ${\Xi }_{cc}^{\ast }\pi (3757)$. These doubly charmed pentaquark states are expected to be identified in future experiments.

   hep-phhep-exhep-latnucl-ex+1PRD(2020)·45 citations
6. 06*

   Revisiting Neutrino Self-Interaction Constraints from $Z$ and $\tau$ decays

   Vedran Brdar🇩🇪 · Manfred Lindner🇩🇪 · Stefan Vogl🇩🇪 · Xun-Jie Xu🇩🇪

   Given the elusive nature of neutrinos, their self-interaction is particularly difficult to probe. Nevertheless, upper limits on the strength of such an interaction can be set by using data from terrestrial experiments. In this work we focus on additional contributions to the invisible decay width of $Z$ boson as well as the leptonic $\tau$ decay width in the presence of a neutrino coupling to a relatively light scalar. For invisible $Z$ decays we derive a complete set of constraints by considering both three-body bremsstrahlung as well as the loop correction to two-body decays. While the latter is usually regarded to give rather weak limits we find that through the interference with the Standard Model diagram it actually yields a competitive constraint. As far as leptonic decays of $\tau$ are concerned, we derive a first limit on neutrino self-interactions that is valid across the whole mass range of a light scalar mediator. Our bounds on the neutrino self-interaction are leading for $m_{\varphi }\gtrsim 300$ MeV and interactions that prefer ${\nu }_{\tau }$. Bounds on such $\nu$-philic scalar are particularly relevant in light of the recently proposed alleviation of the Hubble tension in the presence of such couplings.

   hep-phastro-ph.COPRD(2020)·90 citations
7. 07*

   The "96 GeV excess" at the LHC

   T. Biekötter🇩🇪 · M. Chakraborti🇪🇸 · S. Heinemeyer🇪🇸

   The CMS collaboration reported an intriguing \sim 3 sigma (local) excess at 96 GeV in the light Higgs-boson search in the diphoton decay mode. This mass coincides with a \sim 2 sigma (local) excess in the bb final state at LEP. We briefly review the proposed combined interpretations for the two excesses. In more detail we review the interpretation of this possible signal as the lightest Higgs boson in the 2 Higgs Doublet Model with an additional real Higgs singlet (N2HDM). We show which channels have the best prospects for the discovery of additional Higgs bosons at the upcoming Run 3 of the LHC.

   hep-phInt.J.Mod.Phys.A(2021)·40 citations
8. 08*

   The impact of flavour data on global fits of the MFV SMEFT

   Rafael Aoude🇩🇪 · Tobias Hurth🇩🇪 · Sophie Renner🇮🇹 · William Shepherd🇺🇸

   We investigate the information that can be gained by including flavour data in fits of the Standard Model Effective Field Theory (SMEFT) with the assumption of Minimal Flavour Violation (MFV), allowing - as initial conditions at the high scale - leading terms in spurionic Yukawas only. Starting therefore from a theory with no tree level flavour changing neutral currents at the scale of new physics, we calculate effects in flavour changing processes at one loop, and the resulting constraints on linear combinations of SMEFT coefficients, consistently parameterising the electroweak parameters and the CKM within the SMEFT. By doing a global fit including electroweak, Higgs and low energy precision measurements among others, we show that flavour observables put strong constraints on previously unconstrained operator directions. The addition of flavour data produces four independent constraints at order TeV or above on otherwise flat directions; reducing to three when complete U(3)^5 flavour symmetry is assumed. Our findings demonstrate that flavour remains a stringent test for models of new physics, even in the most flavourless scenario.

   hep-phJHEP(2020)·79 citations
9. 09*

   Precision Theory of Electroweak Interactions

   Michael E. Peskin🇺🇸

   As a part of the celebration of 50 years of the Standard Model of particle physics, I present a brief history of the precision theory of electroweak interactions. I emphasize in particular the theoretical preparations for the LEP program and the prediction of m_t and m_h from the electroweak precision data. [to appear in the proceedings of the SM@50 Symposium, Case Western Reserve University, June 1-4, 2018]

   hep-phphysics.hist-ph1 citation
10. 10*

    Searching for New Physics using Precision Standard Model Measurements

    Michael E. Peskin🇺🇸

    New physics interactions beyond the Standard Model can make themselves known as small corrections to Standard Model reactions. There is a diverse array of proposals for new physics, and so any parametrization of those effects must be as general and all-inclusive as possible. This can be accomplished by the use of Standard Model Effective Field Theory (SMEFT). In this article, part of the celebration of 50 years of the Standard Model of particle physics, I describe how SMEFT has been applied to search for new physics in fermion-fermion scattering and precision electroweak analysis and how it will be applied in the precision study of the Higgs boson. [to appear in the proceedings of the SM@50 Symposium, Case Western Reserve University, June 1-4, 2018]

    hep-phphysics.hist-ph2 citations
11. 11*

    The Search for Electroweakinos

    Anadi Canepa🇺🇸 · Tao Han🇺🇸 · Xing Wang🇺🇸

    In this review, we consider a general theoretical framework for fermionic color-singlet states, including a singlet, a doublet and a triplet under the standard model SU(2)${}_{\mathrm{L}}$ gauge symmetry, corresponding to the Bino, Higgsino and Wino in Supersymmetric theories, generically dubbed as "electroweakinos" for their mass eigenstates. Depending on the relations among their three mass parameters and the mixings after the electroweak symmetry breaking, this sector leads to rich phenomenology potentially accessible at the current and near-future experiments. We discuss the decay patterns of the electroweakinos and their observable signatures at colliders. We review the existing bounds on the model parameters. We summarize the current status for the comprehensive searches from the ATLAS and CMS experiments at the LHC. We comment on the prospects for future colliders. An important feature of the theory is that the lightest neutral electroweakino can be identified as a WIMP cold dark matter candidate. We take into account the existing bounds on the parameters from the dark matter direct detection experiments and discuss the complementarity for the electroweakino searches at colliders.

    hep-phhep-exAnn.Rev.Nucl.Part.Sci.(2020)·36 citations
12. 12*

    Investigating Cosmic Discordance

    Eleonora Di Valentino🇬🇧 · Alessandro Melchiorri🇮🇹 · Joseph Silk🇫🇷

    We show that a combined analysis of CMB anisotropy power spectra obtained by the Planck satellite and luminosity distance data simultaneously excludes a flat universe and a cosmological constant at $99\%$ CL. These results hold separately when combining Planck with three different datasets: the two determinations of the Hubble constant from Riess et al. 2019 and Freedman et al. 2020, and the Pantheon catalog of high redshift supernovae type-Ia. We conclude that either LCDM needs to be replaced by a different model, or else there are significant but still undetected systematics. Our result calls for new observations and stimulates the investigation of alternative theoretical models and solutions.

    ↳ astro-ph.COgr-qchep-phApJL(2021)·230 citations
13. 13*

    Gluonic-Excitation Energies and Abelian Dominance in SU(3) QCD

    Hiroki Ohata (YITP, Kyoto U.)🇯🇵 · Hideo Suganuma (Dept. Phys., Kyoto U.)🇯🇵

    We present the first study of the Abelian-projected gluonic-excitation energies for the static quark-antiquark (Q$\bar{\mathrm{Q}}$) system in SU(3) lattice QCD at the quenched level, using a $32^4$ lattice at $\beta =6.0$. We investigate ground-state and three excited-state Q$\bar{\mathrm{Q}}$ potentials, using smeared link variables on the lattice. We find universal Abelian dominance for the quark confinement force of the excited-state Q$\bar{\mathrm{Q}}$ potentials as well as the ground-state potential. Remarkably, in spite of the excitation phenomenon in QCD, we find Abelian dominance for the first gluonic-excitation energy of about 1 GeV at long distances in the maximally Abelian gauge. On the other hand, no Abelian dominance is observed for higher gluonic-excitation energies even at long distances. This suggests that there is some threshold between 1 and 2 GeV for the applicable excitation-energy region of Abelian dominance. Also, we find that Abelian projection significantly reduces the short-distance $1/r$-like behavior in gluonic-excitation energies.

    ↳ hep-lathep-phhep-thPRD(2020)·3 citations
14. 14*

    A search for dark matter in Triangulum II with the MAGIC telescopes

    MAGIC Collaboration: V. A. Acciari (1) · S. Ansoldi (2,23) · L. A. Antonelli (3) · A. Arbet Engels (4) · D. Baack (5) · A. Babić (6) · B. Banerjee (7) · U. Barres de Almeida (8) · J. A. Barrio (9) · J. Becerra González (1) · W. Bednarek (10) · L. Bellizzi (11) and 163 other authors

    We present the first results from very-high-energy observations of the dwarf spheroidal satellite candidate Triangulum II with the MAGIC telescopes from 62.4 hours of good-quality data taken between August 2016 and August 2017. We find no gamma-ray excess in the direction of Triangulum II, and upper limits on both the differential and integral gamma-ray flux are presented. Currently, the kinematics of Triangulum II are affected by large uncertainties leading to a bias in the determination of the properties of its dark matter halo. Using a scaling relation between the annihilation J-factor and heliocentric distance of well-known dwarf spheroidal galaxies, we estimate an annihilation J-factor for Triangulum II for WIMP dark matter of $\log [J_{\text{ann}}(0.5^{\circ })/$ GeV${}^2$ cm${}^{-5}]=19.35\pm 0.37$. We also derive a dark matter density profile for the object relying on results from resolved simulations of Milky Way sized dark matter halos. We obtain 95% confidence-level limits on the thermally averaged annihilation cross section for WIMP annihilation into various Standard Model channels. The most stringent limits are obtained in the ${\tau }^{+}{\tau }^{-}$ final state, where a cross section for annihilation down to $⟨{\sigma }_{\text{ann}}v⟩=3.05\times 10^{-24}$ cm${}^3$ s${}^{-1}$ is excluded.

    ↳ astro-ph.HEhep-phPhys.Dark Univ.(2020)·26 citations
15. 15*

    Dynamics of Chiral Cosmology

    Andronikos Paliathanasis🇿🇦

    We perform a detailed analysis for the dynamics of Chiral cosmology in a spatially flat Friedmann-Lema\^ıtre-Robertson-Walker universe with a mixed potential term. The stationary points are categorized in four families. Previous results in the literature are recovered while new phases in the cosmological evolution are found. From our analysis we find nine different cosmological solutions, the eight describe scaling solutions, where the one is that of a pressureless fluid, while only one de Sitter solution is recovered.

    ↳ gr-qcastro-ph.COhep-phClass.Quant.Grav.(2020)·51 citations
16. 16*

    Line Bundle Hidden Sectors for Strongly Coupled Heterotic Standard Models

    Anthony Ashmore🇺🇸 · Sebastian Dumitru🇺🇸 · Burt A. Ovrut🇺🇸

    The compactification from the eleven-dimensional Hořava-Witten orbifold to five-dimensional heterotic M-theory on a Schoen Calabi-Yau threefold is reviewed, as is the specific $SU(4)$ vector bundle leading to the "heterotic standard model" in the observable sector. Within the context of strongly coupled heterotic M-theory, a formalism for consistent hidden-sector bundles associated with a single line bundle is presented, and a specific line bundle is introduced as a concrete example. Anomaly cancellation and the associated bulk space five-branes are discussed in this context, as is the constraint that the hidden sector bundle be compatible with the slope-stability requirements of the observable sector $SU(4)$ gauge bundle. The further compactification to a four-dimensional effective theory on a linearized BPS double domain wall is then presented to order ${\kappa }_{11}^{4/3}$. Specifically, the generic constraints required for anomaly cancellation and the restrictions imposed by positive squared gauge couplings to order ${\kappa }_{11}^{4/3}$ are presented in detail. Three additional constraints are imposed, one guaranteeing that the $S^1/{\mathbb{Z}}_2$ orbifold length is sufficiently larger than the average Calabi-Yau radius, and two enforcing that the hidden sector be compatible with both the unification mass scale and unified gauge coupling of the $SO(10)$ group in the observable sector. Finally, the expression for the Fayet-Iliopoulos term associated with an anomalous $U(1)$ symmetry is presented and its role in $N=1$ supersymmetry in the low-energy effective theory is discussed. It is shown that $N=1$ supersymmetry can be preserved by cancelling the tree-level and genus-one contributions against each another.

    ↳ hep-thhep-phFortsch.Phys.(2021)·12 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.