Thu·May 3, 2018Thursday·May 3, 2018

1. 01*

   Dark Matter Relic Density Revisited: The Case For Early Kinetic Decoupling

   Tobias Binder🇩🇪 · Torsten Bringmann🇳🇴 · Michael Gustafsson🇩🇪 · Andrzej Hryczuk🇳🇴

   Kinetic decoupling of dark matter typically happens much later than chemical freeze-out. In fact, local thermal equilibrium is an important assumption for the usual relic density calculations based on solving the Boltzmann equation (for its 0-th moment) describing the dark matter number density. But is this assumption always justified? Here we address this question and discuss the consequences of more accurate treatments. The first treatment is relying on the inclusion of higher moments of the Boltzmann equation and the second on solving the evolution of the phase-space distribution function fully numerically. For illustration, these methods are applied to the Scalar Singlet model, often referred to as the simplest WIMP DM possibility from a model-building perspective. It is explicitly shown that even in this simple model the prediction for the dark matter abundance can be affected by as much as one order of magnitude.

   hep-phastro-ph.CO3 citations
2. 02*

   Inverse seesaw and dark matter in a gauged $\mathrm{B}-\mathrm{L}$ extension with flavour symmetry

   Anirban Biswas🇮🇳 · Sandhya Choubey🇮🇳 · Sarif Khan🇮🇳

   We propose a model which generates neutrino masses by the inverse seesaw mechanism, provides a viable dark matter candidate and explains the muon ($g-2$) anomaly. The Standard Model (SM) gauge group is extended with a gauged U(1)${}_{\mathrm{B}-\mathrm{L}}$ as well as a gauged U(1)${}_{{\mathrm{L}}_{\mu }-{\mathrm{L}}_{\tau }}$. While U(1)${}_{{\mathrm{L}}_{\mu }-{\mathrm{L}}_{\tau }}$ is anomaly free, the anomaly introduced by U(1)${}_{\mathrm{B}-\mathrm{L}}$ is cancelled between the six SM singlet fermions introduced for the inverse seesaw mechanism and four additional chiral fermions introduced in this model. After spontaneous symmetry breaking the four chiral fermionic degrees of freedom combine to give two Dirac states. The lightest Dirac fermion becomes stable and hence the dark matter candidate. We focus on the region of the parameter space where the dark matter annihilates to the right-handed neutrinos, relating the dark matter sector with the neutrino sector. The U(1)${}_{{\mathrm{L}}_{\mu }-{\mathrm{L}}_{\tau }}$ gauge symmetry provides a flavour structure to the inverse seesaw framework, successfully explaining the observed neutrino masses and mixings. We study the model parameters in the light of neutrino oscillation data and find correlation between them. Values of some of the model parameters are shown to be mutually exclusive between normal and inverted ordering of the neutrino mass eigenstates. Moreover, the muon ($g-2$) anomaly can be explained by the additional contribution arising from U(1)${}_{{\mathrm{L}}_{\mu }-{\mathrm{L}}_{\tau }}$ gauge boson.

   hep-phJHEP(2018)·14 citations
3. 03*

   Charged pion condensation under parallel electromagnetic fields

   Jingyi Chao🇨🇳 · Mei Huang🇨🇳 · Andrey Radzhabov🇨🇳

   The formation of charged pion condensate under parallel electromagnetic fields is studied within the two-flavor Nambu--Jona-Lasinio model. The technique of Schwinger proper time method is extended to explore the quantity locating in the off-diagonal flavor space, i.e., charged pion. We obtain the associated effective potential as a function of the strength of the electromagnetic fields and find out that it contains a sextic term which possibly induce weakly first order phase transition. Dependence of pion condensation on model parameters is investigated.

   hep-phnucl-thCPC(2020)·17 citations
4. 04*

   Chromomagnetic and chromoelectric dipole moments of the top quark in the 4GTHDM

   A. I. Hernández-Juárez🇲🇽 · A. Moyotl🇲🇽 · G. Tavares-Velasco🇲🇽

   The chromo magnetic dipole moment (CMDM) and chromo electric dipole moment (CEDM) of the top quark are calculated at the one-loop level in the framework of the two-Higgs doublet model with four fermion generations (4GTHDM), which is still consistent with experimental data and apart from new scalar bosons ($H^0$, $A^0$, and $H^{\pm }$) and quarks ($b^{\prime }$ and $t^{\prime }$) predicts new sources of $CP$ violation via the extended $4\times 4$ CKM matrix. Analytical expressions for the CMDM and CEDM of a quark are presented both in terms of Feynman parameter integrals and Passarino-Veltman scalar functions, with the main contributions arising from loops carrying the scalar bosons accompanied by the third- and fourth-generation quarks. The current bounds on the parameter space of the 4GTHDM are discussed and a region still consistent with the LHC data on the 125 GeV Higgs boson is identified. It is found that the top quark CMDM, which is induced by all the scalar bosons, can reach values of the order of $10^{-4}$-$10^{-3}$, with the dominant contributions arising from the fourth generation quarks, though may also be large cancellations for some parameter values, thereby giving a negligible CMDM. As for the top quark CEDM, it only receives contributions from the charged scalar boson and can reach values of the order of $10^{-19}$-$10^{-18}$ ecm for relatively light $m_{H^{\pm }}$ and large $m_{b^{\prime }}$, with the dominant contribution arising from the $b^{\prime }$ quark. The latter would be the most interesting prediction of this model as can be larger than the value predicted by the usual THDMs by one or two orders of magnitude.

   hep-phPRD(2018)·17 citations
5. 05*

   Self-interacting dark matter and muon $g-2$ in a gauged U$(1{)}_{L_{\mu }-L_{\tau }}$ model

   Ayuki Kamada🇰🇷 · Kunio Kaneta🇰🇷 · Keisuke Yanagi🇯🇵 · Hai-Bo Yu🇺🇸

   We construct a self-interacting dark matter model that could simultaneously explain the observed muon anomalous magnetic moment. It is based on a gauged U$(1{)}_{L_{\mu }-L_{\tau }}$ extension of the standard model, where we introduce a vector-like pair of fermions as the dark matter candidate and a new Higgs boson to break the symmetry. The new gauge boson has a sizable contribution to muon $(g-2)$, while being consistent with other experimental constraints. The U$(1{)}_{L_{\mu }-L_{\tau }}$ Higgs boson acts as a light force carrier, mediating dark matter self-interactions with a velocity-dependent cross section. It is large enough in galaxies to thermalize the inner halo and explain the diverse rotation curves and diminishes towards galaxy clusters. Since the light mediator dominantly decays to the U$(1{)}_{L_{\mu }-L_{\tau }}$ gauge boson and neutrinos, the astrophysical and cosmological constraints are weak. We study the thermal evolution of the model in the early Universe and derive a lower bound on the gauge boson mass.

   hep-phastro-ph.COJHEP(2018)·124 citations
6. 06*

   Observability of 2HDM neutral Higgs bosons with different masses at future $e^{+}{e}^{-}$ linear colliders

   Majid Hashemi🇮🇷 · Gholamhossein Haghighat🇮🇷

   Assuming two Higgs doublet model (2HDM) at SM-like scenario as the theoretical framework, this study addresses the question of observability of heavy neutral CP-even and CP-odd Higgs bosons $H$ and $A$ at a linear collider operating at $\sqrt{s}=1$ TeV. The signal production channel is $e^{-}{e}^{+}\to AH\to ZHH$ with subsequent leptonic decay of the $Z$ boson and Higgs bosons decays into $b$ quark pairs. Therefore, to be specific, type-I 2HDM is used to allow dominant Higgs boson decay to b-quark pairs below the top quark pair production threshold. Two benchmark points with mass ranges $150\le m_H\le 200$ and $250\le m_A\le 300$ are simulated. The relevant energy and momentum smearing is applied and appropriate selection cuts are imposed to enrich signal events. Results indicate that both Higgs bosons are observable with signals exceeding $5\sigma$ significance with possibility of mass measurement at the integrated luminosity of 500 $f{b}^{-1}$.

   hep-phNPB(2020)·7 citations
7. 07*

   Determinations of form factors for semileptonic $D\to K$ decays and leptoquark constraints

   Jian Zhang🇨🇳 · Chong-Xing Yue🇨🇳 · Chun-Hua Li🇨🇳

   By analyzing all existing measurements for $D\to K{\ell }^{+}{\nu }_{\ell }$ ( $\ell =e,\mu$ ) decays, we find that the determinations of both the vector form factor $f_{+}^K(q^2)$ and scalar form factor $f_0^K(q^2)$ for semileptonic $D\to K$ decays from these measurements are feasible. By taking the parameterization of the one order series expansion of the $f_{+}^K(q^2)$ and $f_0^K(q^2)$, $f_{+}^K(0)|V_{cs}|$ is determined to be $0.7182\pm 0.0029$, and the shape parameters of $f_{+}^K(q^2)$ and $f_0^K(q^2)$ are $r_{+1}=-2.16\pm 0.007$ and $r_{01}=0.89\pm 3.27$, respectively. Combining with the average $f_{+}^K(0)$ of $N_f=2+1$ and $N_f=2+1+1$ lattice calculaltion, the $|V_{cs}|$ is extracted to be $0.964\pm 0.004\pm 0.019$ where the first error is experimental and the second theoretical. Alternatively, the $f_{+}^K(0)$ is extracted to be $0.7377\pm 0.003\pm 0.000$ by taking the $|V_{cs}|$ as the value from the global fit with the unitarity constraint of the CKM matrix. Moreover, using the obtained form factors by $N_f=2+1+1$ lattice QCD, we re-analyze these measurements in the context of new physics. Constraints on scalar leptoquarks are obtained for different final states of semileptonic $D\to K$ decays.

   hep-phEPJC(2018)·13 citations
8. 08*

   Decay constants of pseudoscalar and vector mesons with improved holographic wavefunction

   Qin Chang🇨🇳 · Xiao-Nan Li🇨🇳 · Xin-Qiang Li🇨🇳 · Fang Su🇨🇳

   We calculate the decay constants of light and heavy-light pseudoscalar and vector mesons with improved soft-wall holographic wavefuntions, which take into account the effects of both quark masses and dynamical spins. We find that the predicted decay constants, especially for the ratio $f_V/f_P$, based on light-front holographic QCD, can be significantly improved, once the dynamical spin effects are taken into account by introducing the helicity-dependent wavefunctions. We also perform detailed ${\chi }^2$ analyses for the holographic parameters ({\it i.e.} the mass-scale parameter $\kappa$ and the quark masses), by confronting our predictions with the data for the charged-meson decay constants and the meson spectra. The fitted values for these parameters are generally in agreement with those obtained by fitting to the Regge trajectories. At the same time, most of our results for the decay constants and their ratios agree with the data as well as the predictions based on lattice QCD and QCD sum rule approaches, with only a few exceptions observed.

   hep-phhep-exCPC(2018)·47 citations
9. 09*

   Precise QCD Description of the Higgs Boson Transverse Momentum Spectrum

   Xuan Chen🇨🇭 · Thomas Gehrmann🇨🇭 · E.W. Nigel Glover🇬🇧 · Alexander Huss🇨🇭 · Ye Li🇺🇸 · Duff Neill🇺🇸 · Markus Schulze🇩🇪 · Iain W. Stewart🇺🇸 · Hua Xing Zhu🇨🇳

   The transverse momentum ($p_T$) distribution of Higgs bosons at hadron colliders enables a detailed probe of its production dynamics and is a key ingredient to precision studies of Higgs boson properties, but receives very large QCD corrections. We obtain a precision prediction for the $p_T$ spectrum by matching second-order (NNLO) QCD corrections at large $p_T$ with resummation of third-order logarithmic (N${}^3$LL) corrections at small $p_T$. We achieve significantly improved results for $p_T<35\mathrm{GeV}$ with perturbative uncertainties $\lesssim \pm 6\%$, and thus a convergent perturbative series for all values of $p_T$.

   hep-phPLB(2019)·106 citations
10. 10*

    Nonequilibrium axial charge production in expanding glasma flux tubes

    Naoto Tanji🇮🇹

    Axial charge production at the early stage of heavy-ion collisions is investigated within the framework of real-time lattice simulations at leading order in QCD coupling. Starting from color glass condensate initial conditions, the time evolution of quantum quark fields under classical color gauge fields is computed on a lattice in longitudinally expanding geometry. We consider simple color charge distributions in Lorentz contracted nuclei that realize flux tube-like configurations of color fields carrying nonzero topological charge after a collision. By employing the Wilson fermion extended to the longitudinally expanding geometry, we demonstrate the realization of the axial anomaly on the real-time lattice.

    hep-phhep-latnucl-thPRD(2018)·9 citations
11. 11*

    Constraining PDFs from neutral current Drell-Yan measurements and effects of resummation in slepton pair production

    Juri Fiaschi🇩🇪 · Elena Accomando🇬🇧 · Francesco Hautmann🇬🇧 · Michael Klasen🇩🇪 · Stefano Moretti🇬🇧

    The high statistics that will be collected during the LHC Run-II (and beyond) open the path to precision measurements at the TeV scale, where the PDFs will play a crucial role in BSM searches. In the di-lepton final state accurate measurements of the Forward-Backward Asymmetry (AFB) will be available, particularly in the invariant mass region around the Z peak. We show that this observable displays a statistical error which is competitive with that assigned to the existing PDF sets and which will rapidly become smaller than the latter as the integrated luminosity grows, thereby offering a means of constraining the (anti)quark PDFs over a sizeable $(x,Q^2)$ range. In the context of SUSY searches we consider the effects of employing threshold-improved PDFs in a consistent calculation at NLO+NLL of slepton pair production cross sections. The calculations featuring a consistent resummation procedure both at PDF and partonic matrix element level are accompanied by PDF and scale uncertainties, and they provide a reliable and updated theoretical estimation for experimental data analyses at the LHC Run-II.

    hep-ph4 citations
12. 12*

    SUSY scale uncertainties in $m_b(m_b)$: $Br[B_s^0\to {\mu }^{+}{\mu }^{-}]$ and cMSSM

    Abhijit Samanta🇮🇳 · Md Ansarul Haque🇮🇳

    We have studied the SUSY scale dependence of supersymmetric radiative corrections to bottom quark mass on the branching ratio of $B_s^0\to {\mu }^{+}{\mu }^{-}$ and its impact on the cMSSM parameter space. The supersymmetric radiative corrections to bottom quark mass is in general evaluated at the SUSY scale, which is normally considered to be the geometric mean of stop masses. Then, the running of bottom quark mass is considered from the SUSY scale to the matching scale $M_W$ of the effective Hamiltonian which describes this decay. It is found that the branching ratio varies drastically with the SUSY scale. Typically the $Br[B_s^0\to {\mu }^{+}{\mu }^{-}{]}_{\mathrm{untagged}}$ varies $\sim 0.6\times 10^{-9}$ due variation of bottom quark mass $\sim 35\%$ with the SUSY scale and these changes are very significant compared to their present uncertainties in the measurements. Moreover, these variations are very larger at the regions of parameter space which are favorable for producing higgs mass around 125 GeV. Finally, the confrontation of cMSSM with $B_s^0\to {\mu }^{+}{\mu }^{-}$ is drastically relaxed if one lowers the SUSY scale and a significantly large parameter space becomes allowed in the phenomenologically interesting regions.

    hep-phhep-ex0 citations
13. 13*

    Precise prediction of the MSSM Higgs boson masses for low MA

    Henning Bahl🇩🇪 · Wolfgang Hollik🇩🇪

    Precise predictions for Higgs boson masses in the Minimal Supersymmetric Standard Model can be obtained by combining fixed-order calculations with effective field theory (EFT) methods for the resummation of large logarithms in case of heavy superpartners. This hybrid approach is implemented in the computer code FeynHiggs and has been applied in previous studies for calculating the mass of the lightest CP-even Higgs boson for low, intermediate and high SUSY scales. In these works it was assumed that the non-standard Higgs bosons share a common mass scale with the supersymmetric squark particles, leaving the Standard Model as the low-energy EFT. In this article, we relax this restriction and report on the implemention of a Two-Higgs-Doublet Model (THDM) as effective theory below the SUSY scale into our hybrid approach. We explain in detail the various steps how our EFT calculation is consistently combined with the fixed-order calculation within the code FeynHiggs. In our numerical investigation we find effects on the mass of the lightest CP-even Higgs boson h of up to 9 GeV in scenarios with low $M_A$ , low $\tan \beta$ and high SUSY scales, when compared with previous versions of FeynHiggs. Comparisons to other publicly available pure EFT codes with a THDM show good agreement. Effects on the mass of the second lightest CP-even Higgs boson H are found to be negligible in the phenomenologically interesting parameter regions where H can be traded for h as the experimentally observed Higgs particle.

    hep-phJHEP(2018)·54 citations
14. 14*

    Polarization of a vector boson produced in decay of a heavy fermion in an arbitrary frame

    Arunprasath Velusamy🇮🇳 · Ritesh K. Singh🇮🇳

    We consider processes where an electroweak gauge boson ($W$ and $Z$) is produced in the decays of a heavy fermion. The polarization state of the produced gauge boson is given in terms of a vector polarization and a rank-2 tensor polarization. In the rest frame of the mother fermion, these are given directly by the dynamical parameters of the underlying theory. In a frame where the mother particle is moving, the polarization parameters of the gauge boson are dependent additionally upon kinematical factors. We show that these kinematical factors depend only on the magnitude of the velocity of the mother particle and derive analytical expressions for them. We apply the results to pair production of heavy fermions at the LHC with one of the fermions decaying to a gauge boson ($W$, $Z$) and a light Standard Model fermion. We construct estimators of laboratory frame values of polarization parameters of the produced gauge boson. These estimators can be used to estimate the laboratory frame values of polarization parameters of the produced gauge boson without a detailed simulation of the entire process. We validate our expressions with detailed Monte Carlo simulations in the context of beyond the Standard Model scenarios which have a vector-like top partner. We also indicate how to include finite width effects of the heavy fermion in some special cases.

    hep-phPRD(2018)·6 citations
15. 15*

    Nucleon axial form factor from a Bayesian neural-network analysis of neutrino-scattering data

    Luis Alvarez-Ruso🇪🇸 · Krzysztof M. Graczyk🇵🇱 · Eduardo Saul-Sala🇪🇸

    The Bayesian approach for feed-forward neural networks has been applied to the extraction of the nucleon axial form factor from the neutrino-deuteron scattering data measured by the Argonne National Laboratory (ANL) bubble chamber experiment. This framework allows to perform a model-independent determination of the axial form factor from data.. When the low $0.05<Q^2<0.10$ GeV${}^2$ data is included in the analysis, the resulting axial radius disagrees with available determinations. Furthermore, a large sensitivity to the corrections from the deuteron structure is obtained. In turn, when the low-$Q^2$ region is not taken into account, with or without deuteron corrections, no significant deviations from the dipole ansatz have been observed. A more accurate determination of the nucleon axial form factor requires new precise measurements of neutrino-induced quasielastic scattering on hydrogen and deuterium.

    hep-phhep-exnucl-exnucl-thPRC(2019)·35 citations
16. 16*

    On the Properties of Neutrinos

    A. Baha Balantekin🇺🇸 · Boris Kayser🇺🇸

    Our present understanding of neutrino properties is reviewed with a particular emphasis on observable differences between Majorana and Dirac neutrinos. Current and future experimental efforts towards measuring neutrino properties are summarized. Consequences of the Majorana vs.Dirac nature of neutrinos on neutrino masses, neutrino decays, and neutrino electromagnetic properties are described.

    hep-phhep-thnucl-thAnn.Rev.Nucl.Part.Sci.(2018)·95 citations
17. 17*

    Strong CP solution with soft PQ breaking

    Ravi Kuchimanchi

    A recent work combined the popular left-right parity (LR) and Peccei-Quinn (PQ) symmetries to explain the alignment in quark masses. Since axions may not exist, we break PQ softly and discover a new solution to the strong CP problem. Remarkably, since the soft PQ breaking terms respect parity, the strong CP phase is absent at tree-level, while $\bar{\theta }\gtrsim 7\times 10^{-11}$ is generated in two loops. Thus a neutron electric dipole moment close to the current experimental bound is predicted, making the theory falsifiable, even if the scale of new physics is well beyond the reach of colliders. In LR models leptonic CP phases (such as Dirac phase ${\delta }_{CP}$) can generate the strong CP phase in one loop, which is a challenge for their existence. PQ symmetry sets one of the leptonic Yukawa matrices to zero at the tree level and automatically suppresses this contribution, and makes a way for leptonic CP violation to be present.

    hep-phhep-ex3 citations
18. 18*

    The 2016 European School of High-Energy Physics

    Martijn Mulders🇨🇭 · Giulia Zanderighi (CERN)🇨🇭

    The European School of High-Energy Physics is intended to give young physicists an introduction to the theoretical aspects of recent advances in elementary particle physics. These proceedings contain lecture notes on the theory of the Weak interaction and Higgs physics, flavour physics and CP violation, neutrinos, theories beyond the Standard Model, physics at the LHC Run-2 and beyond, practical statistics for high-energy physicists, and cosmology and dark matter.

    hep-phhep-th4 citations
19. 19*

    Exclusive production of pions and the pion distribution amplitude

    D. A. Fagundes🇧🇷 · E. G. S. Luna🇧🇷 · A. A. Natale🇧🇷 · M. Pelaez🇺🇾

    Considering, as a limit case, an approximately flat pion distribution amplitude, which is determined from the hardest, in momentum space, solution of the Bethe-Salpeter equation for the pion wave function, we compute the pion transition form factor $F_{\pi \gamma {\gamma }^{\ast }}(Q^2)$ and the pion form factor $F_{\pi }(Q^2)$, taking into account the LO as well as NLO form of the hard coefficient function entering the leading-twist factorization formula. We also compute the exclusive photoproduction of pions pairs at high energies, $\gamma \gamma \to {\pi }^{+}{\pi }^{-}$, where perturbative QCD can be used to compute the hard scattering matrix elements. We verify that the existent data for exclusive pion production can be reasonably described as a function of such flat distribution amplitude.

    hep-phhep-exnucl-thJ.Phys.G(2020)·1 citation
20. 20*

    Nonperturbatively-renormalized glue momentum fraction at physical pion mass from Lattice QCD

    Yi-Bo Yang🇺🇸 · Ming Gong🇨🇳 · Jian Liang🇺🇸 · Huey-Wen Lin🇺🇸 · Keh-Fei Liu🇺🇸 · Dimitra Pefkou🇺🇸 · Phiala Shanahan🇺🇸

    We present the first nonperturbatively-renormalized determination of the glue momentum fraction $⟨x{⟩}_g$ in the nucleon, based on lattice-QCD simulations at physical pion mass using the cluster-decomposition error reduction (CDER) technique. We provide the first practical strategy to renormalize the glue energy-momentum tensor (EMT) nonperturbatively in the RI/MOM scheme, and convert the results to the $\overline{\text{MS}}$ scheme with 1-loop matching. The simulation results show that the CDER technique can reduce the statistical uncertainty of its renormalization constant by a factor of $\mathcal{O}$(300) in calculations using typical state-of-the-art lattice volume, and the nonperturbatively-renormalized $⟨x{⟩}_g$ is shown to be independent of the lattice definitions of the glue EMT up to discretization errors. We determine the renormalized $⟨x{⟩}_g^{\overline{\text{MS}}}(2\text{ GeV})$ to be 0.47(4)(11) at physical pion mass, which is consistent with the experimentally-determined value.

    ↳ hep-lathep-phnucl-thPRD(2018)·60 citations
21. 21*

    Fast and accurate simulation of particle detectors using generative adversarial networks

    Pasquale Musella🇨🇭 · Francesco Pandolfi🇮🇹

    Deep generative models parametrised by neural networks have recently started to provide accurate results in modelling natural images. In particular, generative adversarial networks provide an unsupervised solution to this problem. In this work we apply this kind of technique to the simulation of particle-detector response to hadronic jets. We show that deep neural networks can achieve high-fidelity in this task, while attaining a speed increase of several orders of magnitude with respect to traditional algorithms.

    ↳ hep-exhep-phphysics.data-anComput.Softw.Big Sci.(2018)·108 citations
22. 22*

    The cosmological constant in Supergravity

    Ignatios Antoniadis🇫🇷 · Auttakit Chatrabhuti🇹🇭 · Hiroshi Isono🇹🇭 · Rob Knoops🇹🇭

    We propose a supersymmetrisation of the cosmological constant in ordinary $N=1$ supergravity that breaks supersymmetry spontaneously by a constant Fayet-Iliopoulos (FI) term associated to a $U(1)$ symmetry. This term is a variation of a new gauge invariant FI term proposed recently, which is invariant under Kähler transformations and can be written even for a gauged R-symmetry on top of the standard FI contribution. The two terms are the same in the absence of matter but differ in its presence. The proposed term is reduced to a constant FI-term up to fermion interactions that disappear in the unitary gauge in the absence of any F-term supersymmetry breaking. The constant FI term leads to a positive cosmological constant, uplifting the vacuum energy from the usual anti-de Sitter supergravity to any higher value.

    ↳ hep-thhep-phEPJC(2018)·45 citations
23. 23*

    Holographic Bjorken flow of a hot and dense fluid in the vicinity of a critical point

    Renato Critelli (Sao Paulo U.)🇧🇷 · Romulo Rougemont (Rio de Janeiro State U.)🇧🇷 · Jorge Noronha (Sao Paulo U.)🇧🇷

    In this paper we use the gauge/gravity duality to perform the first systematic study of the onset of hydrodynamic behavior in a hot and dense far-from-equilibrium strongly coupled relativistic fluid with a critical point. By employing a top-down holographic construction that stems from string theory, we numerically obtain the full nonlinear evolution of the far-from-equilibrium system undergoing a Bjorken expansion and address the following question: how does hydrodynamic behavior emerge in the vicinity of a critical point in the phase diagram? For the top-down holographic system analyzed in the present work, we find that the approach to hydrodynamics is strongly affected by the presence of the critical point: the closer the ratio between the chemical potential and the temperature is to its critical value, the longer it takes for the system to be well described by the equations of viscous hydrodynamics.

    ↳ hep-thhep-phnucl-thPRD(2019)·39 citations
24. 24*

    Racing through the swampland: de Sitter uplift vs weak gravity

    Jakob Moritz🇩🇪 · Thomas Van Riet🇧🇪

    We observe that racetrack models for moduli stabilization are in tension with strong forms of the Weak Gravity Conjecture (WGC). Moreover, recently, it was noted that controlled KKLT-type de Sitter vacua seem to require a racetrack fine-tuning of the type introduced by Kallosh and Linde. We combine these observations and conclude that the quests for realizing parametrically large axion decay constants and controlled de Sitter vacua are intimately related. Finally, we discuss possible approaches to curing the conflict between the racetrack scheme and the WGC.

    ↳ hep-thhep-phJHEP(2018)·34 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.