Tue·Nov 6, 2018Tuesday·November 6, 2018

1. 01*

   Probing anomalous $tq\gamma$ and $tqg$ couplings via single top production in association with photon at FCC-hh

   K.Y. Oyulmaz🇹🇷 · A. Senol🇹🇷 · H. Denizli🇹🇷 · A. Yilmaz🇹🇷 · I. Turk Cakir🇹🇷 · O. Cakir🇹🇷

   We study the anomalous FCNC $tq\gamma$ and $tqg$ couplings via $pp\to Wb\gamma +X$ signal process including realistic detector effects for both leptonic and hadronic decay channels of the W boson at 100 TeV FCC-hh. The relevant background are considered in the cut based analysis to obtain not only limits on the anomalous $\lambda$ and $\zeta$ couplings but also branching ratios of $t\to q\gamma$ and $t\to qg$ decay channels. We find that the sensitivity to the branching ratio of $t\to q\gamma$ channel is three order better than the available LHC experimental limits, and it is comparable for the branching ratio of the $t\to qg$ decay channel with an integrated luminosity of 10 ab${}^{-1}$ at 2$\sigma$ significance level.

   hep-phEPJC(2019)·12 citations
2. 02*

   Dark matter and LHC phenomenology of a scale invariant scotogenic model

   Chao Guo🇨🇳 · Shu-Yuan Guo🇨🇳 · Yi Liao🇨🇳

   We study the phenomenology of a model that addresses the neutrino mass, dark matter, and generation of the electroweak scale in a single framework. Electroweak symmetry breaking is realized via the Coleman-Weinberg mechanism in a classically scale invariant theory, while the neutrino mass is generated radiatively through interactions with dark matter in a typically scotogenic manner. The model introduces a scalar triplet and singlet and a vector-like fermion doublet that carry an odd parity of $Z_2$, and an even parity scalar singlet that helps preserve classical scale invariance. We sample over the parameter space by taking into account various experimental constraints from the dark matter relic density and direct detection, direct scalar searches, neutrino mass, and charged lepton flavor violating decays. We then examine by detailed simulations possible signatures at the LHC to find some benchmark points of the free parameters. We find that the future high-luminosity LHC will have a significant potential in detecting new physics signals in the dilepton channel.

   hep-phCPC(2019)·6 citations
3. 03*

   The ${\mu }^{+}{\mu }^{-}$ collider to sensitivity estimates on the magnetic and electric dipole moments of the tau-lepton

   M. Köksal🇹🇷 · A. A. Billur🇹🇷 · A. Gutiérrez-Rodríguez🇲🇽 · M. A. Hernández-Ruíz🇲🇽

   Using the effective Lagrangian formalism, the anomalous magnetic and electric dipole moments of the tau-lepton in the ${\mu }^{+}{\mu }^{-}\to {\mu }^{+}{\gamma }^{\ast }{\gamma }^{\ast }{\mu }^{-}\to {\mu }^{+}\tau \bar{\tau }{\mu }^{-}$ process at the future muon colliders at the $\sqrt{s}=1.5,3$ and $6$ TeV are investigated. In addition, the bounds at the $95\%$ confidence level on the dipole moments of the tau-lepton using different integrated luminosities are estimated. It is shown that the ${\mu }^{+}{\mu }^{-}\to {\mu }^{+}{\gamma }^{\ast }{\gamma }^{\ast }{\mu }^{-}\to {\mu }^{+}\tau \bar{\tau }{\mu }^{-}$ process leads to a remarkable improvement in the existing experimental bounds on the anomalous magnetic and electric dipole moments of the tau-lepton.

   hep-phInt.J.Mod.Phys.A(2019)·21 citations
4. 04*

   Rapidity gaps and ancestry

   Dung Le Anh🇫🇷 · Stéphane Munier🇫🇷

   The recently discovered correspondence between the distribution of rapidity gaps in electron-nucleus diffractive processes and the statistics of the height of genealogical trees in branching random walks is reviewed. In addition, a new comparison of numerical solutions of exact equations for diffraction on the one hand, and for ancestry on the other hand, both established in the framework of the color dipole model, is presented.

   hep-phActa Phys.Polon.Supp.(2019)·2 citations
5. 05*

   Tensions between the appearance data of T2K and NOvA

   Mohammad Nizam🇮🇳 · Suman Bharti🇮🇳 · Suprabh Prakash🇧🇷 · Ushak Rahaman🇮🇳 · S. Uma Sankar🇮🇳

   The long baseline neutrino experiments, T2K and NOvA, have taken significant amount of data in each of the four channels: (a) ${\nu }_{\mu }$ disappearance, (b) ${\bar{\nu }}_{\mu }$ disappearance (c) ${\nu }_e$ appearance and (d) ${\bar{\nu }}_e$ appearance. There is a mild tension between the disappearance and the appearance data sets of T2K. A more serious tension exists between the ${\nu }_e$ appearance data of T2K and the ${\nu }_e/{\bar{\nu }}_e$ appearance data of NOvA. This tension is significant enough that T2K rules out the best-fit point of NOvA at $95\%$ confidence level whereas NOvA rules out T2K best-fit point at $90\%$ confidence level. We explain the reason why these tensions arise. We also do a combined fit of T2K and NOvA data and comment on the results of this fit.

   hep-phhep-exMod.Phys.Lett.A(2019)·9 citations
6. 06*

   Activating the 4th Neutrino of the 3+1 Scheme

   Peter B. Denton🇺🇸 · Yasaman Farzan🇮🇷 · Ian M. Shoemaker🇺🇸

   Non-Standard Interactions (NSI) of neutrinos with matter has received renewed interest in recent years. In particular, it has been shown that NSI can reconcile the $3+1$ solution with IceCube atmospheric data with $E_{\nu }>500$ GeV, provided that the effective coupling of NSI is large, e.g. $\sim 6G_F$. The main goal of the present paper is to show that contrary to intuition, it is possible to build viable models with large NSI by invoking a new $U(1)$ gauge symmetry with gauge boson of mass $\sim 10$ eV. We refer to these new constructions as $3+1+U(1)$ models. In the framework of a $3+1$ solution to LSND and MiniBooNE anomalies, we show that this novel NSI can help to solve the tension with cosmological bounds and constraints from IceCube atmospheric data with $E_{\nu }>500$ GeV. We then discuss the implications of the MINOS and MINOS+ results for the 3+1+$U(1)$ scenario.

   hep-phhep-exPRD(2019)·57 citations
7. 07*

   X(3872) in the molecular model

   Yu.S. Kalashnikova🇷🇺 · A.V. Nefediev🇷🇺

   We discuss methods and approaches to the description of molecular states in the spectrum of heavy quarks and investigate in detail various properties of the exotic charmonium-like state X(3872) in the framework of the mesonic molecule model.

   hep-phhep-exPhys.Usp.(2019)·85 citations
8. 08*

   The problems of ${\eta }^{\prime }\to {\pi }^0\gamma \gamma$ decay and the New Physics

   Yaroslav Balytskyi🇺🇸

   Rare decays of light mesons may be a discovery window for a new weakly coupled forces hidden at low energy QCD scale. BES-III Collaboration reported the observation of the rare decay ${\eta }^{\prime }\to {\pi }^0\gamma \gamma$. The observed decay width disagrees with the preliminary theoretical estimations. We show that this tension may be attributed to the New Physics, presumably Dark Photon. For completeness, we consider the possible influence of the New Physics on a similar well-measured decay $\eta \to {\pi }^0\gamma \gamma$ and a recently measured one ${\eta }^{\prime }\to \eta \gamma \gamma$ and show that the impact of the hypothetical Dark Photon may be also present in these decays also.

   hep-phLHEP(2020)·5 citations
9. 09*

   Locally-constant field approximation in studies of electron-positron pair production in strong external fields

   I. A. Aleksandrov🇷🇺 · G. Plunien🇩🇪 · V. M. Shabaev🇷🇺

   In the present investigation we revisit the widely-used locally-constant field approximation (LCFA) in the context of the pair-production phenomenon in strong electromagnetic backgrounds. By means of nonperturbative numerical calculations, we assess the validity of the LCFA considering several spatially homogeneous field configurations and a number of space-time-dependent scenarios. By studying the momentum spectra of particles produced, we identify the criteria for the applicability of the LCFA. It is demonstrated that the Keldysh parameter itself does not allow one to judge if the LCFA should perform accurately. In fact, the external field parameters must obey less trivial relations whose form depends on the field configuration. We reveal several generic properties of these relations which can also be applied to a broader class of other pair-production scenarios.

   hep-phPRD(2019)·48 citations
10. 10*

    Transverse Momentum Resummation for $s$-channel single top quark production at the LHC

    Peng Sun🇨🇳 · Bin Yan🇺🇸 · C.-P. Yuan🇺🇸

    We study the soft gluon radiation effects for the $s$-channel single top quark production at the LHC. By applying the transverse momentum dependent factorization formalism, the large logarithms about the small total transverse momentum ($q_{\perp }$) of the single-top plus one-jet final state system, are resummed to all orders in the expansion of the strong interaction coupling at the accuracy of Next-to-Leading Logarithm (NLL). We compare our numerical results with PYTHIA and find that both the $q_{\perp }$ and ${\varphi }^{\ast }$ observables from PYTHIA are consistent with our prediction. Furthermore, we point out the soft gluon radiation effects from the final state become significant in this process, especially for the boosted kinematical region.

    hep-phhep-exPRD(2019)·11 citations
11. 11*

    Study of $s\to d\nu \bar{\nu }$ rare hyperon decays within the Standard Model and new physics

    Xiao-Hui Hu🇨🇳 · Zhen-Xing Zhao🇨🇳

    FCNC processes offer important tools to test the Standard Model (SM), and to search for possible new physics. In this work, we investigate the $s\to d\nu \bar{\nu }$ rare hyperon decays in SM and beyond. We find that in SM the branching ratios for these rare hyperon decays range from $10^{-14}$ to $10^{-11}$. When all the errors in the form factors are included, we find that the final branching fractions for most decay modes have an uncertainty of about $5\%$ to $10\%$. After taking into account the contribution from new physics, the generalized SUSY extension of SM and the minimal 331 model, the decay widths for these channels can be enhanced by a factor of $2\sim 7$.

    hep-phhep-exCPC(2019)·9 citations
12. 12*

    Analytical properties of the gluon propagator from truncated Dyson-Schwinger equation in complex Euclidean space

    L. P. Kaptari🇨🇳 · B. Kaempfer🇩🇪 · P. Zhang🇨🇳

    We suggest a framework based on the rainbow approximation with effective parameters adjusted to lattice data. The analytic structure of the gluon and ghost propagators of QCD in Landau gauge is analyzed by means of numerical solutions of the coupled system of truncated Dyson-Schwinger equations. We find that the gluon and ghost dressing functions are singular in complex Euclidean space with singularities as isolated pairwise conjugated poles. These poles hamper solving numerically the Bethe-Salpeter equation for glueballs as bound states of two interacting dressed gluons. Nevertheless, we argue that, by knowing the position of the poles and their residues, a reliable algorithm for numerical solving the Bethe-Salpeter equation can be established.

    hep-phhep-th2 citations
13. 13*

    Precision study of $W^{-}{W}^{+}H$ production including parton shower effects at the CERN Large Hadron Collider

    Huan-Yu Bi🇨🇳 · Ren-You Zhang🇨🇳 · Wen-Gan Ma🇨🇳 · Yi Jiang🇨🇳 · Xiao-Zhou Li🇨🇳 · Peng-Fei Duan🇨🇳

    The precision study of $W^{-}{W}^{+}H$ production with subsequent $W^{\pm }\to l^{\pm }\stackrel{{}_{(-)}}{{\nu }_l}$ and $H\to b\bar{b}$ decays at the LHC can help us to study the Higgs gauge couplings and to search for new physics beyond the SM. In this paper, we calculate the shower-matched NLO QCD correction and the EW corrections from the $q\bar{q}$ annihilation and photon-induced channels to the $W^{-}{W}^{+}H$ production at the $14\mathrm{TeV}$ LHC, and deal with the subsequent decays of Higgs and $W^{\pm }$ bosons by adopting the {\sc MadSpin} method. Both the integrated cross section and some kinematic distributions of $W^{\pm }$, $H$ and their decay products are provided. We find that the QCD correction enhances the LO differential cross section significantly, while the EW correction from the $q\bar{q}$ annihilation channel obviously suppresses the LO differential cross section, especially in the high energy phase-space region due to the Sudakov effect. The $q\gamma$- and $\gamma \gamma$-induced relative corrections are positive, and insensitive to the transverse momenta of $W^{\pm }$, $H$ and their decay products. These photon-induced corrections compensate the negative $q\bar{q}$-initiated EW correction, and become the dominant EW contribution as the increment of the $pp$ colliding energy. The parton shower (PS) effects on the kinematic distributions are nonnegligible. The PS relative correction to the $b$-jet transverse momentum distribution can exceed $100\%$ in the high $p_{T,b}$ region. We also investigate the scale and PDF uncertainties, and find that the theoretical error of the $\mathrm{QCD}+\mathrm{EW}+q\gamma +\gamma \gamma$ corrected integrated cross section mainly comes from the renormalization scale dependence of the QCD correction.

    hep-phCPC(2019)·1 citation
14. 14*

    Seesaw mechanism and pseudo C-symmetry

    Kazuo Fujikawa🇯🇵 · Anca Tureanu🇫🇮

    It is shown that the specific "charge conjugation" transformation used to define the Majorana fermions in the conventional seesaw mechanism, namely $({\nu }_R{)}^C=C{\overline{{\nu }_R}}^T$ for a chiral fermion ${\nu }_R$ (and similarly for ${\nu }_L$), is a hidden symmetry associated with CP symmetry, and thus it formally holds independently of the P- and C-violating terms in the CP invariant Lagrangian and it is in principle applicable to charged leptons and quarks as well. This hidden symmetry, however, is not supported by a consistent unitary operator and thus it leads to mathematical (operatorial) ambiguities. When carefully examined, it also fails as a classical transformation law in a Lorentz invariant field theory. To distinguish it from the standard charge conjugation symmetry, we suggest for it the name of pseudo C-symmetry. The pseudo C-symmetry is effective to identify Majorana neutrinos analogously to the classical Majorana condition. The analysis of CP breaking in weak interactions is performed using the conventional CP transformation, which is defined independently of the pseudo C-transformation, in the seesaw model after mass diagonalization. A way to ensure an operatorially consistent formulation of C-conjugation is to formulate the seesaw scheme by invoking a relativistic analogue of the Bogoliubov transformation.

    hep-phhep-thEPJC(2019)·9 citations
15. 15*

    Determining ${\alpha }_s$ from hadronic $\tau$ decay: the pitfalls of truncating the OPE

    D. Boito🇧🇷 · M. Golterman🇺🇸 · K. Maltman🇨🇦 · S. Peris🇪🇸

    We discuss sum-rule determinations of ${\alpha }_s$ from non-strange hadronic $\tau$-decay data. We investigate, in particular, the reliability of the assumptions underlying the "truncated OPE strategy," which specifies a certain treatment of non-perturbative contributions, and which was employed in Refs. [1-3]. Here, we test this strategy by applying the strategy to the $R$-ratio obtained from $e^{+}{e}^{-}$ data, which extend beyond the $\tau$ mass, and, based on the outcome of these tests, we demonstrate the failure of this strategy.We then present a brief overview of new results on the form of duality-violating non-perturbative contributions, which are conspicuously present in the experimentally determined spectral functions. As we show, with the current precision claimed for the extraction of ${\alpha }_s$, including a representation of duality violations is unavoidable if one wishes to avoid uncontrolled theoretical errors.

    hep-phhep-latnucl-thSciPost Phys.Proc.(2019)·6 citations
16. 16*

    Intensity of gluon bremsstrahlung in a finite plasma

    Xabier Feal🇪🇸 · Ricardo Vazquez🇪🇸

    The intensity of single gluon bremsstrahlung in a QCD plasma is evaluated with a Monte Carlo which solves the transport equation for a generic interaction with the medium. In particular the calculation is performed for a Debye screened potential and compared to the well known Gaussian/Fokker-Planck results. The full calculation including the first and last gluons show a qualitatively different behavior from the BDMPS result for any finite medium length. It is shown that the emission intensity is underestimated for the Gaussian approximation, compared to the Debye screened potential. This change can not be accounted for by a redefinition of the Gaussian parameter ($\hat{q}$).

    hep-phPRD(2018)·45 citations
17. 17*

    Renormalization-group improvement in hadronic $\tau$ decays in 2018

    D. Boito🇧🇷 · P. Masjuan🇪🇸 · F. Oliani🇧🇷

    One of the main sources of theoretical uncertainty in the extraction of the strong coupling from hadronic tau decays stems from the renormalization-group improvement of the series. Perturbative series in QCD are divergent but are (most likely) asymptotic expansions. One needs knowledge about higher orders to be able to choose the optimal renormalization-scale setting procedure. Here, we discuss the use of Padé approximants as a model-independent and robust method to extract information about the higher-order terms. We show that in hadronic $\tau$ decays the fixed-order expansion, known as fixed-order perturbation theory (FOPT), is the most reliable mainstream method to set the scale. This fully corroborates previous conclusions based on the available knowledge about the leading renormalon singularities of the perturbative series.

    hep-phSciPost Phys.Proc.(2019)·3 citations
18. 18*

    Studies on gluon evolution and geometrical scaling in kinematic constrained unitarized BFKL equation: application to high-precision HERA DIS data

    P. Phukan🇮🇳 · M. Lalung🇮🇳 · J. K. Sarma🇮🇳

    We suggest a modified form of a unitarized BFKL equation imposing the so-called kinematic constraint on the gluon evolution in multi-Regge kinematics. The underlying nonlinear effects on the gluon evolution are investigated by solving the unitarized BFKL equation analytically. We obtain an equation of the critical boundary between dilute and dense partonic system, following a new differential geometric approach and sketch a phenomenological insight on geometrical scaling. Later we illustrate the phenomenological implication of our solution for unintegrated gluon distribution $f(x,k_T^2)$ towards exploring high precision HERA DIS data by theoretical prediction of proton structure functions ($F_2$ and $F_L$) as well as double differential reduced cross section $({\sigma }_r)$. The validity of our theory in the low $Q^2$ transition region is established by studying virtual photon-proton cross section in light of HERA data.

    hep-phEPJC(2019)·3 citations
19. 19*

    Decays of Pentaquarks in Hadrocharmonium and Molecular Pictures

    Michael I. Eides🇺🇸 · Victor Yu. Petrov🇷🇺

    We consider decays of the hidden charm LHCb pentaquarks in the hadrocharmonium and molecular scenarios. In both pictures the LHCb pentaquarks are essentially nonrelativistic bound states. We develop a semirelativistic framework for calculation of the partial decay widths that allows the final particles to be relativistic. Using this approach we calculate the decay widths in the hadrocharmonium and molecular pictures. Molecular hidden charm pentaquarks are constructed as loosely bound states of charmed and anticharmed hadrons. Calculations show that molecular pentaquarks decay predominantly into states with open charm. Strong suppression of the molecular pentaquark decays into states with hidden charm is qualitatively explained by a relatively large size of the molecular pentaquark. The decay pattern of hadrocharmonium pentaquarks that are interpreted as loosely bound states of excited charmonium ${\psi }^{\prime }$ and nucleons is quite different. This time dominate decays into states with hidden charm, but suppression of the decays with charm exchange is weaker than in the respective molecular case. The weaker suppression is explained by a larger binding energy and respectively smaller size of the hadrocharmonium pentaquarks. These results combined with the experimental data on partial decay widths could allow to figure out which of the two theoretical scenarios for pentaquarks (if either) is chosen by nature.

    hep-phPRD(2018)·12 citations
20. 20*

    Algorithmics of Diffraction

    Mikael Mieskolainen🇫🇮

    We discuss novel ways to probe high energy diffraction, first inclusive diffraction and then central exclusive processes at the LHC. Our new Monte Carlo synthesis and analysis framework, Graniitti, includes differential screening, an expendable set of scattering amplitudes with adaptive Monte Carlo sampling, spin systematics and modern computational technology.

    hep-phhep-exActa Phys.Polon.Supp.(2019)·0 citations
21. 21*

    Revisiting the Number-Theory Dark Matter Scenario and the Weak Gravity Conjecture

    Kazunori Nakayama🇯🇵 · Fuminobu Takahashi🇯🇵 · Tsutomu T. Yanagida🇯🇵

    We revisit the number-theory dark matter scenario where one of the light chiral fermions required by the anomaly cancellation conditions of U(1)_{B-L} explains dark matter. Focusing on some of the integer B-L charge assignments, we explore a new region of the parameter space where there appear two light fermions and the heavier one becomes a dark matter of mass O(10)keV or O(10)MeV. The dark matter radiatively decays into neutrino and photon, which can explain the tantalizing hint of the 3.55keV X-ray line excess. Interestingly, the other light fermion can erase the AdS vacuum around the neutrino mass scale in a compactification of the standard model to 3D. This will make the standard model consistent with the AdS-WGC statement that stable non-supersymmetric AdS vacua should be absent.

    hep-phhep-thPLB(2019)·16 citations
22. 22*

    Temperature dependence of $\eta /s$: uncertainties from the equation of state

    Jussi Auvinen🇷🇸 · Kari J. Eskola🇫🇮 · Pasi Huovinen🇵🇱 · Harri Niemi🇩🇪 · Risto Paatelainen🇨🇭 · Peter Petreczky🇺🇸

    We perform a global model-to-data comparison on Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV and Pb+Pb collisions at $2.76$ TeV and $5.02$ TeV, using a 2+1D hydrodynamics model with the EKRT initial state and a shear viscosity over entropy density ratio $(\eta /s)(T)$ with a linear $T$ dependence. To quantify the amount of uncertainty due to the choice of the equation of state (EoS), we compare analysis results based on four different EoSs: the well known $s95p$ parametrisation, an updated parametrisation based on the same list of particles in hadron resonance gas, but using recent lattice results for the partonic part of the EoS, and two new parametrisations based on the Particle Data Group 2016 particle list and the recent lattice results. We find that the choice of the EoS does affect the favoured minimum value of $\eta /s$, although within the confidence limits of the analysis. On the other hand, our analysis hardly constrains the temperature dependence of $\eta /s$, no matter the EoS.

    hep-phnucl-thPoS(2018)·4 citations
23. 23*

    The ${\Omega }_c$-puzzle solved by means of spectrum and strong decay amplitude predictions

    E. Santopinto🇮🇹 · A. Giachino🇮🇹 · J. Ferretti🇺🇸 · H. García-Tecocoatzi🇮🇹 · M. A. Bedolla🇮🇹 · M R. Bijker🇲🇽 · E. Ortiz-Pacheco🇲🇽

    The observation of new ${\Omega }_c=ssc$ states by LHCb \cite{Aaij:2017nav} and the confirmation of four of them by Belle \cite{Yelton:2017qxg} may represent an important milestone in our understanding of the quark organization inside hadrons. By providing results for the spectrum of ${\Omega }_{c(b)}$ baryons and predictions for their ${\Xi }_{c(b)}^{+}{K}^{-}$ decay channels, we suggest a possible solution to the ${\Omega }_c$ quantum number puzzle. We also discuss why the set of ${\Omega }_{c(b)}$ baryons are the most suitable environment to test the validity of three-quark and quark-diquark effective degrees of freedom. Finally, we calculate the masses and the partial decay widths of the ${\Xi }_b(6227)$ and ${\Sigma }_b(6097)$ states, just observed by LHCb \cite{Aaij:2018yqz,Aaij:2018tnn}. Our results are in good agreement with LHCb experimental data.

    hep-phEPJC(2019)·50 citations
24. 24*

    The strong coupling from $e^{+}{e}^{-}\to$ hadrons

    Diogo Boito🇧🇷 · Maarten Golterman🇺🇸 · Alex Keshavarzi🇬🇧 · Kim Maltman🇨🇦 · Daisuke Nomura🇯🇵 · Santiago Peris🇪🇸 · Thomas Teubner🇬🇧

    We use a new compilation of the hadronic $R$-ratio from available data for the process $e^{+}{e}^{-}\to$ hadrons below the charm mass to determine the strong coupling ${\alpha }_s$, using finite-energy sum rules. Quoting our results at the $\tau$ mass to facilitate comparison to the results obtained from similar analyses of hadronic $\tau$-decay data, we find ${\alpha }_s(m_{\tau }^2)=0.298\pm 0.016\pm 0.006$ in fixed-order perturbation theory, and ${\alpha }_s(m_{\tau }^2)=0.304\pm 0.018\pm 0.006$ in contour-improved perturbation theory, where the first error is statistical, and the second error combines various systematic effects. These values are in good agreement with a recent determination from the OPAL and ALEPH data for hadronic $\tau$ decays. We briefly compare the $R(s)$-based analysis with the $\tau$-based analysis.

    hep-phSciPost Phys.Proc.(2019)·1 citation
25. 25*

    Higgs pair production from bottom quark annihilation to NNLO in QCD

    Ajjath A H🇮🇳 · Pulak Banerjee🇮🇳 · Amlan Chakraborty🇮🇳 · Prasanna K. Dhani🇮🇹 · Pooja Mukherjee🇮🇳 · Narayan Rana🇮🇹 · V. Ravindran🇮🇳

    We present the first results on the two-loop massless QCD corrections to the four-point amplitude $b+\overline{b}\to H+H$ in the five flavor scheme, treating bottom quarks as massless. This amplitude is sensitive to the trilinear Higgs boson coupling. Our two-loop result for this amplitude constitutes of purely virtual contributions to the next-to-next-to-leading order QCD predictions for the production of a pair of Higgs bosons at the Large Hadron Collider. Using these two loop amplitudes and exploiting the universality of the soft contributions in perturbative QCD, we obtain the NNLO QCD effects in the soft plus virtual approximation. We find that the inclusion of higher order terms reduce the uncertainties resulting from the unphysical renormalisation and factorisation scales.

    hep-phhep-exJHEP(2019)·18 citations
26. 26*

    Anisotropic hydrodynamics for Au-Au collisions at 200 GeV

    Mubarak Alqahtani🇸🇦 · Dekrayat Almaalol🇺🇸 · Michael Strickland🇺🇸

    In this proceedings, we review the basics of quasiparticle anisotropic hydrodynamics (aHydroQP). Thenwe present phenomenological comparisons between 3+1d quasiparticle anisotropic hydrodynamics and experimental data from RHIC experiments at 200 GeV Au-Au collisions. We show that 3+1d aHydroQP model is able to describe the experimental results quite well for the spectra, multiplicity, and elliptic flow for charged particles in different centrality classes.

    hep-phnucl-thMDPI Proc.(2019)·2 citations
27. 27*

    Electromagnetic properties of singly heavy baryons

    June-Young Kim🇰🇷 · Hyun-Chul Kim🇰🇷

    In this presentation, we summarize selectively recent results of the electromagnetic form factors of singly heavy baryons with spin 1/2 and related quantities, which were derived within a framework of the self-consistent chiral quark-soliton model. The results are compared with those from the lattice QCD and their physical implications are discussed.

    hep-phhep-exhep-latSpringer Proc.Phys.(2020)·1 citation
28. 28*

    Resolving the SELEX-LHCb double-charm baryon conflict: the impact of intrinsic heavy-quark hadroproduction and supersymmetric light-front holographic QCD

    Sergey Koshkarev🇪🇪 · Stefan Groote🇪🇪

    In this paper we review the hadroproduction mechanisms of double-charm baryons for the different experimental environments and reinterpret the SELEX and LHCb results.

    hep-phEPJ Web Conf.(2019)·1 citation
29. 29*

    Moduli Portal Dark Matter

    Debtosh Chowdhury🇫🇷 · Emilian Dudas🇫🇷 · Maíra Dutra🇫🇷 · Yann Mambrini🇫🇷

    We show that moduli fields as mediators between the Standard Model and the dark sector can naturally lead to the observed relic abundance. Indeed, even if moduli are very massive, the nature of their couplings with matter and gauge fields allows producing a sufficiently large amount of dark matter in the early Universe through the freeze-in mechanism. Moreover, the complex nature of the moduli fields whose real and imaginary part couple differently to the thermal bath gives an interesting and unusual phenomenology compared to other freeze-in models of that type.

    hep-phastro-ph.COastro-ph.HEPRD(2019)·61 citations
30. 30*

    Cosmic phase transitions: their applications and experimental signatures

    Anupam Mazumdar🇳🇱 · Graham White🇨🇦

    The study of cosmic phase transitions are of central interest in modern cosmology. In the standard model of cosmology the Universe begins in a very hot state, right after at the end of inflation via the process of reheating/preheating, and cools to its present temperature as the Universe expands. Both new and existing physics at any scale can be responsible for catalyzing either first, second or cross over phase transition, which could be either thermal or non-thermal with a potential observable imprints. Thus this field prompts a rich dialogue between gravity, particle physics and cosmology. It is all but certain that at least two cosmic phase transitions have occurred - the electroweak and the QCD phase transitions. The focus of this review will be primarily on phase transitions above such scales, We review different types of phase transitions that can appear in our cosmic history, and their applications and experimental signatures in particular in the context of exciting gravitational waves, which could be potentially be constrained by LIGO/VIRGO, Kagra, and eLISA.

    hep-phRept.Prog.Phys.(2019)·305 citations
31. 31*

    Audible Axions

    Camila S. Machado🇩🇪 · Wolfram Ratzinger🇩🇪 · Pedro Schwaller🇩🇪 · Ben A. Stefanek🇩🇪

    Conventional approaches to probing axions and axion-like particles (ALPs) typically rely on a coupling to photons. However, if this coupling is extremely weak, ALPs become invisible and are effectively decoupled from the Standard Model. Here we show that such invisible axions, which are viable candidates for dark matter, can produce a stochastic gravitational wave background in the early universe. This signal is generated in models where the invisible axion couples to a dark gauge boson that experiences a tachyonic instability when the axion begins to oscillate. Incidentally, the same mechanism also widens the viable parameter space for axion dark matter. Quantum fluctuations amplified by the exponentially growing gauge boson modes source chiral gravitational waves. For axion decay constants $f\gtrsim 10^{17}$ GeV, this signal is detectable by either pulsar timing arrays or space/ground-based gravitational wave detectors for a broad range of axion masses, thus providing a new window to probe invisible axion models.

    hep-phastro-ph.COJHEP(2019)·110 citations
32. 32*

    End-point resummation in squark decays

    Chul Kim🇰🇷 · Jeong Han Kim🇺🇸 · Seung J. Lee🇰🇷 · Jure Zupan🇺🇸

    We study soft and collinear gluon emission in squark decays to quark--neutralino pair, at next-to-next-to-leading logarithmic (NNLL) accuracy in the end-point region, using Soft Collinear Effective Theory (SCET), and at next-to-leading (NLO) fixed order in the rest of the phase space. As a phenomenological case study we discuss the impact of radiative corrections on the simultaneous measurements of squark and neutralino masses at a linear $e^{+}{e}^{-}$ collider based on $\sqrt{s}=3$ TeV Compact Linear Collider (CLIC). Since the majority of mass measurement techniques are based on edges in kinematic distributions, and these change appreciably when there is additional QCD radiation in the final state, the knowledge of higher-order QCD effects is required for precise mass determinations.

    hep-phPRD(2020)·0 citations
33. 33*

    Naturalness Sum Rules and Their Collider Tests

    Csaba Csáki🇺🇸 · Felipe Ferreira De Freitas🇨🇳 · Li Huang🇨🇳 · Teng Ma🇨🇳 · Maxim Perelstein🇺🇸 · Jing Shu🇨🇳

    We present the most general sum rules reflecting the cancellation of ultraviolet divergences in the Higgs potential in weakly-coupled, natural extensions of the Standard Model. There is a separate sum rule for the cancellation of the quadratic and logarithmic divergences, and their forms depend on whether the divergences are canceled by same-spin or opposite-spin partners. These sum rules can be applied to mass eigenstates and conveniently used for direct collider tests of naturalness. We study in detail the feasibility of testing these sum rules in the top sector at a future $100\text{TeV}$ proton collider within two benchmark models, the Little Higgs (LH) and the Maximally Symmetric Composite Higgs (MSCH). We show how the two ingredients of the sum rules, the top partner masses and their Yukawa couplings to the Higgs, can be measured with sufficient accuracy to provide a highly non-trivial quantitative test of the sum rules. In particular, we study observables sensitive to the sign of the top partner Yukawa, which is crucial for verifying the sum rules but is notoriously difficult to measure. We demonstrate that in the benchmark models under study, a statistically significant discrimination between the two possible signs of each Yukawa will be feasible with a 30 ab${}^{-1}$ data set at $100\text{TeV}$.

    hep-phJHEP(2019)·5 citations
34. 34*

    Primordial Lithium Puzzle and the Axion Quark Nugget Dark Matter Model

    Victor V. Flambaum🇦🇺 · Ariel R. Zhitnitsky🇨🇦

    Astrophysics today faces a number of mysteries which defiant their resolutions in spite of drastic improvements in instrumental design, better technique being developed, and gradual improvements in theoretical and computation methods over last decades. Primordial Lithium Puzzle is known to stay with us for at least two decades, and it is very likely that its final resolution will require some fundamentally new ideas, novel frameworks and a non-conventional paradigms. We propose that Primordial Lithium Puzzle finds its natural resolution within the so-called Axion Quark Nugget (AQN) dark matter model. This model was invented long ago as a natural explanation of the observed ratio ${\Omega }_{\mathrm{dark}}\sim {\Omega }_{\mathrm{visible}}$ without any references to BBN physics. In this new paradigm, in contrast with conventional WIMP (Weakly Interacting Massive Particle) framework the dark matter (DM) takes the form of the macroscopically large quark nuggets without requiring any new fields beyond the standard model physics, except for the axion. The time evolution of these AQNs in primordial soup at $T\sim 20$ KeV suggests a strong suppression of the abundances of nuclei with high charges $Z\ge 3$. This suppression mechanism represents the resolution of the primordial lithium abundance within AQN dark matter scenario.

    hep-phastro-ph.COnucl-thPRD(2019)·39 citations
35. 35*

    Precision study of GeV-scale resonant leptogenesis

    J. Ghiglieri🇨🇭 · M. Laine🇨🇭

    Low-scale leptogenesis is most efficient in the limit of an extreme mass degeneracy of right-handed neutrino flavours. Two variants of this situation are of particular interest: large neutrino Yukawa couplings, which boost the prospects of experimental scrutiny, and small ones, which may lead to large lepton asymmetries surviving down to T < 5 GeV. We study benchmarks of these cases within a "complete" framework which tracks both helicity states of right-handed neutrinos as well as their kinetic non-equilibrium, and includes a number of effects not accounted for previously. For two right-handed flavours with GeV-scale masses, Yukawa couplings up to $|h|\sim 0.7\times 10^{-5}$ are found to be viable for baryogenesis, with $\Delta M/M\sim 10^{-8}$ as the optimal degeneracy. Late-time lepton asymmetries are most favourably produced with $\Delta M/M\sim 10^{-11}$. We show that the system reaches a stationary state at T < 15 GeV, in which lepton asymmetries can be more than $10^3$ times larger than the baryon asymmetry, reach flavour equilibrium, and balance against helicity asymmetries.

    hep-phJHEP(2019)·51 citations
36. 36*

    Non-extensive Motivated Parton Fragmentation Functions

    Adam Takacs🇭🇺 · Gergely Gábor Barnaföldi🇭🇺

    A new form of fragmentation function is presented here, motivated by earlier non-extensive studies of jet fragmentation. We parametrized our Tsallis-like function on pion spectra and compared it to the most common fragmentation function parametrizations. It is shown that the new form is in agreement with earlier parametrizations, furthermore, its scale evolution overlap better with the experimental data.

    hep-phnucl-thMDPI Proc.(2019)·3 citations
37. 37*

    Unphysical properties of the static quark-antiquark four-point correlator in Landau gauge

    Jeff Greensite🇺🇸 · Evan Owen🇺🇸

    We consider the four point connected correlator representing a static quark-antiquark pair separated by a spatial distance R, propagating for a Euclidean time T. This function is computed by lattice Monte Carlo in SU(2) pure gauge theory at lattice couplings $\beta =2.2$ and $\beta =2.5$ in both Coulomb and Landau gauges. The Coulomb gauge correlator is well behaved, and is dominated at large T by a state whose energy grows linearly as $\sigma R$, with $\sigma$ the known asymptotic string tension. The connected correlator in Landau gauge behaves differently. At intermediate R there is clear evidence of a linear potential, but the corresponding string tension extrapolates to zero at large T. At large R the connected correlator becomes negative; moreover there are strong finite size effects. These numerical results suggest that unphysical states dominate the large Euclidean time behavior of this Landau gauge correlator.

    ↳ hep-lathep-phPRD(2019)·0 citations
38. 38*

    Novel method for measuring charm-mixing parameters using multibody decays

    A. Di Canto🇨🇭 · J. Garra Ticó🇬🇧 · T. Gershon🇬🇧 · N. Jurik🇬🇧 · M. Martinelli🇨🇭 · T. Pilař🇬🇧 · S. Stahl🇨🇭 · D. Tonelli🇮🇹

    We propose a novel method to measure flavor-oscillations and charge-parity (CP) violation in charm mixing. The approach uses multibody charm decays, such as $D^0\to K_S^0{\pi }^{+}{\pi }^{-}$, and avoids the need for a fit of the decay amplitudes while suppressing biases due to nonuniform signal-reconstruction efficiencies as functions of phase space and decay time. Data are partitioned in decay-time and Dalitz-plot regions (bins). The Dalitz-plot bins are symmetric with respect to the principal bisector and chosen to ensure nearly constant values of the strong-interaction phases in each. The ratios of signal yields observed in each symmetric bin pair are fit as functions of decay time, using independent auxiliary measurements of the strong-interaction phases as constraints, to determine the relevant physics parameters. Simulation shows that this approach improves the sensitivity to the normalized charm-eigenstate mass difference by 35% with respect to existing model-independent methods. In addition, we introduce a parametrization of oscillation and CP-violation effects in charm mixing that has attractive statistical properties and may find wider applicability.

    ↳ hep-exhep-phPRD(2019)·51 citations
39. 39*

    A universal bound on Quantum Chaos from Random Matrix Theory

    Sayantan Choudhury🇩🇪 · Arkaprava Mukherjee🇮🇳

    In this article, using the principles of Random Matrix Theory (RMT), we give a measure of quantum chaos by quantifying Spectral From Factor (SFF) appearing from the computation of two-point Out of Time Order Correlation function (OTOC) expressed in terms of square of the commutator bracket of quantum operators which are separated in time. We also provide a strict model independent bound on the measure of quantum chaos, $-1/N(1-1/\pi )\le \mathbf{SFF}\le 0$ and $0\le \mathbf{SFF}\le 1/\pi N$, valid for thermal systems with a large and small number of degrees of freedom respectively. Based on the appropriate physical arguments we give a precise mathematical derivation to establish this alternative strict bound of quantum chaos.

    ↳ hep-thcond-mat.stat-mechgr-qchep-ph+1JHEP(2019)·10 citations
40. 40*

    Theory of two-pion photo- and electroproduction off the nucleon

    Helmut Haberzettl🇺🇸 · Kanzo Nakayama🇺🇸 · Yongseok Oh🇰🇷

    A theory of two-pion photo- and electroproduction off the nucleon is derived considering all explicit three-body mechanisms of the interacting $\pi \pi N$ system. The full three-body dynamics of the interacting $\pi \pi N$ system is accounted for by the Faddeev-type ordering structure of the Alt-Grassberger-Sandhas equations. The formulation is valid for hadronic two-point and three-point functions dressed by arbitrary internal mechanisms provided all associated electromagnetic currents are constructed to satisfy their respective (generalized) Ward-Takahashi identities. It is shown that coupling the photon to the Faddeev structure of the underlying hadronic two-pion production mechanisms results in a natural expansion of the full two-pion photoproduction current $M_{\pi \pi }^{\mu }$ in terms of multiple dressed loops involving two-body subsystem scattering amplitudes of the $\pi \pi N$ system that preserves gauge invariance as a matter of course order by order in the number of (dressed) loops. A closed-form expression is presented for the entire gauge-invariant current $M_{\pi \pi }^{\mu }$ with complete three-body dynamics. Individually gauge-invariant truncations of the full dynamics most relevant for practical applications at the no-loop, one-loop, and two-loop levels are discussed in detail. An approximation scheme to the full two-pion amplitude for calculational purposes is also presented. It approximates, systematically, the full amplitude to any desired order of expansion in the underlying hadronic two-body amplitude. Moreover, it allows for the approximate incorporation of all neglected higher-order mechanisms in terms of a phenomenological remainder current. The effect and phenomenological usefulness of this remainder current is assessed in a tree-level calculation of the $\gamma N\to KK\Xi$ reaction.

    ↳ nucl-thhep-phnucl-exPRD(2019)·9 citations
41. 41*

    In-medium properties of SU(3) baryons

    Ki-Hoon Hong🇰🇷 · Ulugbek Yakhshiev🇰🇷 · Hyun-Chul Kim🇰🇷

    Changes of baryon properties in nuclear matter are investigated within the framework of an in-medium modified SU(3) Skyrme model. Introducing the medium functionals in the SU(2) sector and considering the alteration of kaon properties in nuclear medium, we are able to examine the medium modification of the nucleon and hyperons. The functionals introduced in the SU(2) sector are related to ordinary nuclear matter properties near the saturation point. The results indicate that the changes of the baryon properties in the strange sector are strongly correlated with the in-medium properties of kaons.

    ↳ nucl-thhep-phSpringer Proc.Phys.(2020)·0 citations
42. 42*

    $J/\psi$ production as a function of charged-particle multiplicity with ALICE at the LHC

    Dhananjaya Thakur (for the ALICE Collaboration)🇮🇳

    At LHC energies, the charged-particle multiplicity dependence of particle production is a topic of considerable interest in $pp$ collisions. It has been argued that multiple partonic interactions play an important role in particle production mechanisms, not only affecting the soft processes but also the hard processes. Recently, ALICE has measured $J/\psi$ production as a function of charged-particle multiplicity to study the correlation between soft and hard processes. In this contribution, we present the $J/\psi$ production versus multiplicity for $pp$ and $p-Pb$ collisions measured by ALICE. We compare the results with different theoretical models.

    ↳ hep-exhep-phSpringer Proc.Phys.(2019)·9 citations
43. 43*

    Improved study of the $\beta$-function of $SU(3)$ gauge theory with $N_f=10$ massless domain-wall fermions

    Ting-Wai Chiu🇹🇼

    I perform an improved study of the $\beta$-function of $SU(3)$ lattice gauge theory with $N_f=10$ massless optimal domain-wall fermions in the fundamental representation, which serves as a check to what extent the scenario in the previous work [arXiv:1603.08854; Proc. Sci. LATTICE2016 (2017) 228] is valid. In the finite-volume gradient flow scheme with $c=\sqrt{8t}/L=0.3$, the renormalized couplings $g^2(L,a)$ of four primary lattices ($L/a=\{8,10,12,16\}$) are tuned (in $6/g_0^2$) to the same $g_c^2$ with statistical error less than $0.5\%$, in contrast to the previous work where $g^2(L,a)$ were obtained by the cubic-spline interpolation. Then the renormalized couplings $g^2(sL,a)$ of the scaled lattices ($sL/a=\{16,20,24,32\}$ with $s=2$) are computed at the same $6/g_0^2$ of the corresponding primary lattices. Using the renormalized couplings of four lattice pairs $(sL,L)/a=\{(16,8),(20,10),(24,12),(32,16)\}$, the step-scaling $\beta$-function $[g^2(sL,a)-g^2(L,a)]/\ln (s^2)$ is computed and extrapolated to the continuum limit $\beta (s,g_c^2)$, as summarized in Table III. Based on the four data points of $\beta (s,g_c^2)$ at $g_c^2=\{6.86(2),6.92(3),7.03(2),7.16(2)\}$, I infer that the theory is infrared near-conformal, or conformal with the fixed-point $g_{\ast }^2=7.55(36)$. This corrects the scenario in the previous work with $g_{\ast }^2\sim 7.0$, and also suggests that the interpolation method cannot give a reliable determination of the $\beta$-function, especially in the regime close to the infrared fixed-point.

    ↳ hep-lathep-phhep-thPRD(2019)·23 citations
44. 44*

    Approximate sum rule for the electric dipole moment of light nuclei

    Nodoka Yamanaka🇫🇷

    The measurement of the electric dipole moment (EDM) is an excellent test of the standard model of particle physics, and the detection of a finite value is signal of a new source of CP violation beyond it. Among systems for which the EDM can be measured, light nuclei are particularly interesting due to their high sensitivity to new physics. In this proceedings contribution, we examine the sensitivity of the EDM of several light nuclei to the CP-odd one pion-exchange nucleon-nucleon interaction within the cluster model. We suggest an approximate sum rule for the nuclear EDM.

    ↳ nucl-thhep-exhep-phnucl-exSpringer Proc.Phys.(2020)·0 citations
45. 45*

    Quantum Monte Carlo calculations of dark matter scattering off light nuclei

    Lorenzo Andreoli🇺🇸 · Vincenzo Cirigliano🇺🇸 · Stefano Gandolfi🇺🇸 · Francesco Pederiva🇮🇹

    We compute the matrix elements for elastic scattering of dark matter (DM) particles off light nuclei (${}^2$H, ${}^3$H, ${}^3$He, ${}^4$He and ${}^6$Li) using quantum Monte Carlo methods. We focus on scalar-mediated DM-nucleus interactions and use scalar currents obtained to next-to-leading order in chiral effective theory. The nuclear ground states are obtained from a phenomenological nuclear Hamiltonian that includes the Argonne $v_{18}$ two-body interaction and the three-body Urbana IX interaction. Within this approach, we study the impact of one- and two-body currents and discuss the size of nuclear uncertainties, including for the first time two-body effects in $A=4$ and $A=6$ systems. Our results provide the nuclear structure input needed to assess the sensitivity of future experimental searches of (light) dark matter using light nuclei, such as ${}^3$He and ${}^4$He.

    ↳ nucl-thhep-phPRC(2019)·25 citations
46. 46*

    Fluid dynamics of heavy ion collisions with Mode expansion (FluiduM)

    Stefan Floerchinger🇩🇪 · Eduardo Grossi🇩🇪 · Jorrit Lion🇩🇪

    The fluid dynamics of a relativistic fireball with longitudinal and transverse expansion is described using a background-fluctuation splitting. Symmetry representations of azimuthal rotations and longitudinal boosts are used for a classification of initial state configurations and their fluid dynamic propagation in terms of a mode expansion. We develop an accurate and efficient numerical scheme based on the pseudo-spectral method to solve the resulting hyperbolic partial differential equations. Comparison to the analytically known Gubser solution underlines the high accuracy of this technique. We also present first applications of FluiduM to central heavy ion collisions at the LHC energies featuring a realistic thermodynamic equations of state as well as shear and bulk viscous dissipation.

    ↳ nucl-thhep-phPRC(2019)·36 citations
47. 47*

    Intrinsic multipole moments of the non-Gaussian wave packets

    Dmitry Karlovets🇷🇺 · Alexey Zhevlakov🇷🇺

    The charged wave packets with non-Gaussian spatial profiles are shown to possess intrinsic multipole moments. The magnetic dipole moment and the electric quadrupole moment are found for a wide class of the packets, including the vortex electrons with orbital angular momentum $\ell$, the Airy beams, the so-called Schrödinger's cat states, and their generalizations. For the packets with no phase vortices, the electric quadrupole moment is shown to grow quadratically with the packet's width, $|Q_{\alpha \beta }|\sim e\cdot {\sigma }_{\perp }^2$, while it is also $|\ell |$ times enhanced for the vortex beams. For available beams of electron microscopes, these multipole moments are relatively easily adjusted and can be quite large, which affects the packets' electromagnetic fields and also allows one to develop new diagnostic tools for materials science, atomic and molecular physics, nuclear physics, and so forth.

    ↳ quant-phhep-phphysics.atom-phphysics.opticsPRA(2019)·20 citations
48. 48*

    A Bound on Massive Higher Spin Particles

    Nima Afkhami-Jeddi🇺🇸 · Sandipan Kundu🇺🇸 · Amirhossein Tajdini🇺🇸

    According to common lore, massive elementary higher spin particles lead to inconsistencies when coupled to gravity. However, this scenario was not completely ruled out by previous arguments. In this paper, we show that in a theory where the low energy dynamics of the gravitons are governed by the Einstein-Hilbert action, any finite number of massive elementary particles with spin more than two cannot interact with gravitons, even classically, in a way that preserves causality. This is achieved in flat spacetime by studying eikonal scattering of higher spin particles in more than three spacetime dimensions. Our argument is insensitive to the physics above the effective cut-off scale and closes certain loopholes in previous arguments. Furthermore, it applies to higher spin particles even if they do not contribute to tree-level graviton scattering as a consequence of being charged under a global symmetry such as ${\mathbb{Z}}_2$. We derive analogous bounds in anti-de Sitter spacetime from analyticity properties of correlators of the dual CFT in the Regge limit. We also argue that an infinite tower of fine-tuned higher spin particles can still be consistent with causality. However, they necessarily affect the dynamics of gravitons at an energy scale comparable to the mass of the lightest higher spin particle. Finally, we apply the bound in de Sitter to impose restrictions on the structure of three-point functions in the squeezed limit of the scalar curvature perturbation produced during inflation.

    ↳ hep-thgr-qchep-phJHEP(2019)·71 citations
49. 49*

    F-theory and Dark Energy

    Jonathan J. Heckman🇺🇸 · Craig Lawrie🇺🇸 · Ling Lin🇺🇸 · Gianluca Zoccarato🇺🇸

    Motivated by its potential use as a starting point for solving various cosmological constant problems, we study F-theory compactified on the warped product ${\mathbb{R}}_{\text{time}}\times S^3\times Y_8$ where $Y_8$ is a $Spin(7)$ manifold, and the $S^3$ factor is the target space of an $SU(2)$ Wess--Zumino--Witten (WZW) model at level $N$. Reduction to M-theory exploits the abelian duality of this WZW model to an $S^3/{\mathbb{Z}}_N$ orbifold. In the large $N$ limit, the untwisted sector is captured by 11D supergravity. The local dynamics of intersecting 7-branes in the $Spin(7)$ geometry is controlled by a Donaldson--Witten twisted gauge theory coupled to defects. At late times, the system is governed by a 1D quantum mechanics system with a ground state annihilated by two real supercharges, which in four dimensions would appear as "$\mathcal{N}=1/2$ supersymmetry" on a curved background. This leads to a cancellation of zero point energies in the 4D field theory but a split mass spectrum for superpartners of order $\Delta m_{\text{4D}}\sim \sqrt{M_{\text{IR}}{M}_{\text{UV}}}$ specified by the IR and UV cutoffs of the model. This is suggestively close to the TeV scale in some scenarios. The classical 4D geometry has an intrinsic instability which can produce either a collapsing or expanding Universe, the latter providing a promising starting point for a number of cosmological scenarios. The resulting 1D quantum mechanics in the time direction also provides an appealing starting point for a more detailed study of quantum cosmology.

    ↳ hep-thastro-ph.COgr-qchep-phFortsch.Phys.(2019)·99 citations
50. 50*

    Parameterizing Dark Energy Models and Study of Finite Time Future Singularities

    Tanwi Bandyopadhyay · Ujjal Debnath🇮🇳

    A review on spatially flat D-dimensional Friedmann-Robertson-Walker (FRW) model of the universe has been performed. Some standard parameterizations of the equation of state parameter of the Dark Energy models are proposed and the possibilities of finite time future singularities are investigated. It is found that certain types of these singularities may appear by tuning some parameters appropriately. Moreover, for a scalar field theoretic description of the model, it was found that the model undergoes bouncing solutions in some favorable cases.

    ↳ gr-qchep-phhep-thAdv.High Energy Phys.(2019)·4 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.