Mon·Jul 15, 2019Monday·July 15, 2019

1. 01*

   Polarizability of the nucleon

   Martin Schumacher🇩🇪

   The status of the experimental and theoretical investigations on the polarizabilities of the nucleon is presented. This includes a confirmation of the validity of the previously introduced recommended values of the polarizabilities [1,2]. It is shown that the only meaningful approach to a prediction of the polarizabilities is obtained from the nonsubtracted dispersion theory, where the appropriate degrees of freedom taken from other precise experimental data are taken in account. The present values of the recommended polarizabilities are ${\alpha }_p=12.0\pm 0.5$, ${\beta }_p=1.9\mp 0.5$, ${\alpha }_n=12.6\pm 1.2$, ${\beta }_n=2.6\mp 1.2$ in units of $10^{-4}$fm${}^3$ and ${\gamma }_{\pi }^{(p)}=-36.4\pm 1.5$, ${\gamma }_{\pi }^{(n)}=+58.6\pm 4.0$, ${\gamma }_0^{(p)}=-0.58\pm 0.20$, ${\gamma }_0^{(n)}=+0.38\pm 0.22$ in units of $10^{-4}$fm${}^4$.

   hep-phLHEP(2019)·2 citations
2. 02*

   Violation of the Kluberg-Stern--Zuber theorem in SCET

   Martin Beneke🇩🇪 · Mathias Garny🇩🇪 · Robert Szafron🇩🇪 · Jian Wang🇩🇪

   A classic result, originally due to Kluberg-Stern and Zuber, states that operators that vanish by the classical equation of motion (eom) do not mix into "physical" operators. Here we show that and explain why this result does not hold in soft-collinear effective theory (SCET) for the renormalization of power-suppressed operators. We calculate the non-vanishing mixing of eom operators for the simplest case of $N$-jet operators with a single collinear field in every direction. The result implies that---for the computation of the anomalous dimension but not for on-shell matrix elements---there exists a preferred set of fields that must be used to reproduce the infrared singularities of QCD scattering amplitudes. We identify these fields and explain their relation to the gauge-invariant SCET Lagrangian. Further checks reveal another generic property of SCET beyond leading power, which will be relevant to resummation at the next-to-leading logarithmic level, the divergence of convolution integrals with the hard matching coefficients. We propose an operator solution that allows to consistently renormalize such divergences.

   hep-phhep-thJHEP(2019)·68 citations
3. 03*

   Electroweak corrections to the fermionic decays of heavy Higgs states

   Florian Domingo🇩🇪 · Sebastian Paßehr🇫🇷

   Extensions of the Standard Model often come with additional, possibly electroweakly charged Higgs states, the prototypal example being the Two-Higgs-Doublet Model. While collider phenomenology does not exclude the possibility for some of these new scalar fields to be light, it is relatively natural to consider masses in the multi-TeV range, in which case the only remaining light Higgs boson automatically receives SM-like properties. The appearance of a hierarchy between the new-physics states and the electroweak scale then leads to sizable electroweak corrections, e. g. in the decays of the heavy Higgs bosons, which are dominated by effects of infrared type, namely Sudakov logarithms. Such radiative contributions obviously affect the two-body decays, but should also be paired with the radiation of electroweak gauge bosons (or lighter Higgs bosons) for a consistent picture at the one-loop order. Resummation of the leading terms is also relatively easy to achieve. We re-visit these questions in the specific case of the fermionic decays of heavy Higgs particles in the Next-to-Minimal Supersymmetric Standard Model, in particular pointing out the consequences of the three-body final states for the branching ratios of the heavy scalars.

   hep-phEPJC(2019)·14 citations
4. 04*

   Astrophysical limits on very light axion-like particles from Chandra grating spectroscopy of NGC 1275

   Christopher S. Reynolds🇬🇧 · M.C. David Marsh🇸🇪 · Helen R. Russell🇬🇧 · Andrew C. Fabian🇬🇧 · Robyn N. Smith🇺🇸 · Francesco Tombesi🇺🇸 · Sylvain Veilleux🇬🇧

   Axions/axion-like particles (ALPs) are a well motivated extension of the Standard Model and are generic within String Theory. The X-ray transparency of the intracluster medium (ICM) in galaxy clusters is a powerful probe of light ALPs (with mass $<10^{-11}\mathrm{eV}$); as X-ray photons from an embedded or background source propagate through the magnetized ICM, they may undergo energy-dependent quantum mechanical conversion into ALPs (and vice versa), imprinting distortions on the X-ray spectrum. We present Chandra data for the active galactic nucleus NGC1275 at the center of the Perseus cluster. Employing a 490ks High-Energy Transmission Gratings (HETG) exposure, we obtain a high-quality 1-9keV spectrum free from photon pileup and ICM contamination. Apart from iron-band features, the spectrum is described by a power-law continuum, with any spectral distortions at the $<3\%$ level. We compute photon survival probabilities as a function of ALP mass $m_a$ and ALP-photon coupling constant $g_{a\gamma }$ for an ensemble of ICM magnetic field models, and then use the NGC1275 spectrum to constraint the $(m_a,g_{a\gamma })$-plane. Marginalizing over magnetic field realizations, the 99.7% credible region limits the ALP-photon coupling to $g_{a\gamma }<6-8\times 10^{-13}{\mathrm{GeV}}^{-1}$ (depending upon magnetic field model) for masses $m_a<1\times 10^{-12}\mathrm{eV}$. These are the most stringent limit to date on $g_{a\gamma }$ for these light ALPs, and have already reached the sensitivity limits of next-generation helioscopes and light-shining-through-wall experiments. We highlight the potential of these studies with the next-generation X-ray observatories Athena and Lynx, but note the critical importance of advances in relative calibration of these future X-ray spectrometers.

   hep-phastro-ph.COastro-ph.HEApJ(2020)·215 citations
5. 05*

   A nonunitary interpretation for a single vector leptoquark combined explanation to the $B$-decay anomalies

   C. Hati🇫🇷 · J. Kriewald🇫🇷 · J. Orloff🇫🇷 · A.M. Teixeira🇫🇷

   In order to simultaneously account for both $R_{D^{(\ast )}}$ and $R_{K^{(\ast )}}$ anomalies in $B$-decays, we consider an extension of the Standard Model by a single vector leptoquark field, and study how one can achieve the required lepton flavour non-universality, starting from a priori universal gauge couplings. While the unitary quark-lepton mixing induced by $SU(2{)}_L$ breaking is insufficient, we find that effectively nonunitary mixings hold the key to simultaneously address the $R_{K^{(\ast )}}$ and $R_{D^{(\ast )}}$ anomalies. As an intermediate step towards various UV-complete models, we show that the mixings of charged leptons with additional vector-like heavy leptons successfully provide a nonunitary framework to explain $R_{K^{(\ast )}}$ and $R_{D^{(\ast )}}$. These realisations have a strong impact for electroweak precision observables and for flavour violating ones: isosinglet heavy lepton realisations are already excluded due to excessive contributions to lepton flavour violating $Z$-decays. Furthermore, in the near future, the expected progress in the sensitivity of charged lepton flavour violation experiments should allow to fully probe this class of vector leptoquark models.

   hep-phJHEP(2019)·43 citations
6. 06*

   Neutrinos from Type Ia and failed core-collapse supernovae at dark matter detectors

   Nirmal Raj🇨🇦

   Neutrinos produced in the hot and dense interior of the next galactic supernova would be visible at dark matter experiments in coherent elastic nuclear recoils. While studies on this channel have focused on successful core-collapse supernovae, a thermonuclear (Type Ia) explosion, or a core-collapse that fails to explode and forms a black hole, are as likely to occur as the next galactic supernova event. I show that generation-3 noble liquid-based dark matter experiments such as DARWIN and ARGO, operating at sub-keV thresholds with ionization-only signals, would distinguish between (a) leading hypotheses of Type Ia explosion mechanisms by detecting an $\mathcal{O}$(1) s burst of $\mathcal{O}$(1) MeV neutrinos, and (b) progenitor models of failed supernovae by detecting an $\mathcal{O}$(1) s burst of $\mathcal{O}$(10) MeV neutrinos, especially by marking the instant of black hole formation from abrupt stoppage of neutrino detection. This detection is sensitive to all neutrino flavors and insensitive to neutrino oscillations, thereby making measurements complementary to neutrino experiments.

   hep-phastro-ph.HEhep-exPRL(2020)·23 citations
7. 07*

   Predictions of ${\rm Y}(4S)\to h_b(1P,2P){\pi }^{+}{\pi }^{-}$ transitions

   Yun-Hua Chen🇨🇳

   In this work, we study the contributions of the intermediate bottomoniumlike $Z_b$ states and the bottom meson loops in the heavy quark spin flip transitions ${\rm Y}(4S)\to h_b(1P,2P){\pi }^{+}{\pi }^{-}$. Depending on the constructive or destructive interferences between the $Z_b$-exchange and the bottom meson loops mechanisms, we predict two possible branching ratios for each process: BR${}_{{\rm Y}(4S)\to h_b(1P){\pi }^{+}{\pi }^{-}}\simeq (1.2_{-0.4}^{+0.8}\times 10^{-6})$ or $(0.5_{-0.2}^{+0.5}\times 10^{-6})$, and BR${}_{{\rm Y}(4S)\to h_b(2P){\pi }^{+}{\pi }^{-}}\simeq (7.1_{-1.1}^{+1.7}\times 10^{-10})$ or $(2.4_{-0.1}^{+0.2}\times 10^{-10})$. The bottom meson loops contribution is found to be much larger than the $Z_b$-exchange contribution in the ${\rm Y}(4S)\to h_b(1P)\pi \pi$ transitions, while it can not produce decay rates comparable to the heavy quark spin conserved ${\rm Y}(4S)\to {\rm Y}(1S,2S)\pi \pi$ processes. We also predict the branch fractions of $\psi (3S,4S)\to h_c(1P){\pi }^{+}{\pi }^{-}$ contributed from the charm meson loops.

   hep-phhep-exnucl-thCPC(2020)·7 citations
8. 08*

   Theory perspectives on rare Kaon decays and CPV

   Giancarlo D'Ambrosio🇮🇹

   The following proceedings contain a theory perspective on rare Kaon decays. I review rare kaon decays in the LHC era: we discuss interplay with B-anomalies and possible New Physics in direct CP violation in $K\to 2\pi$: very rare kaon decays like $K\to \pi \nu \bar{\nu }$ are very important to this purpose. We discuss also the decays $K^0\to {\mu }^{+}{\mu }^{-}$ due to the LHCB measurement

   hep-ph0 citations
9. 09*

   On Searches for Gravitational Dark Matter with Quantum Sensors

   Xavier Calmet🇬🇧

   The possibility of searching for dark matter with quantum sensors has recently received a lot of attention. In this short paper, we discuss the possibility of searching for gravitational dark matter with quantum sensors and identify a very narrow window of opportunity for future quantum sensors with improved sensitivity. Gravitational dark matter candidates with masses in the range $[10^{-3},1]\text{eV}$ could lead to an effective time variation of the proton mass that could be measured with, e.g., future atomic clocks.

   hep-phquant-phEur.Phys.J.Plus(2019)·8 citations
10. 10*

    Monopole-antimonopole pair production by magnetic fields

    Arttu Rajantie🇬🇧

    Quantum electrodynamics predicts that in a strong electric field, electron-positron pairs are produced by the Schwinger process, which can be interpreted as quantum tunnelling through the Coulomb potential barrier. If magnetic monopoles exist, monopole-antimonopole pairs would be similarly produced in strong magnetic fields by the electromagnetic dual of this process. The production rate can be computed using semiclassical techniques without relying on perturbation theory, and therefore it can be done reliably in spite of the monopoles' strong coupling to the electromagnetic field. This article explains this phenomenon and discusses the bounds on monopole masses arising from the strongest magnetic fields in the Universe, which are in neutron stars known as magnetars and in heavy ion collision experiments such as lead-lead collisions carried out in November 2018 in the Large Hadron Collider at CERN. It will also discuss open theoretical questions affecting the calculation.

    hep-phPhil.Trans.Roy.Soc.Lond.A(2019)·10 citations
11. 11*

    On the nature of the lowest-lying odd parity charmed baryon ${\Lambda }_c(2595)$ and ${\Lambda }_c(2625)$ resonances

    Juan Nieves🇪🇸 · Rafael Pavao🇪🇸

    We study the structure of the ${\Lambda }_c(2595)$ and ${\Lambda }_c(2625)$ resonances in the framework of an effective field theory consistent with heavy quark spin and chiral symmetries, that incorporates the interplay between ${\Sigma }_c^{(\ast )}\pi -N{D}^{(\ast )}$ baryon-meson degrees of freedom and bare P-wave $c\bar{u}d$ quark-model states. We show that these two resonances are not HQSS partners. The $J^P=3/2^{-}$ ${\Lambda }_c(2625)$ should be viewed mostly as a dressed three quark state, whose origin is determined by a bare state, predicted to lie very close to the mass of the resonance. The $J^P=1/2^{-}$ ${\Lambda }_c(2595)$ seems to have, however, a predominant molecular structure. This is because, it is either the result of the chiral ${\Sigma }_c\pi$ interaction, which threshold is located much more closer than the mass of the bare three-quark state, or because the light degrees of freedom in its inner structure are coupled to the unnatural $0^{-}$ quantum-numbers. We show that both situations can occur depending on the renormalization procedure used. We find some additional states, but the classification of the spectrum in terms of HQSS is difficult, despite having used interactions that respect this symmetry. This is because the bare quark-model state and the ${\Sigma }_c\pi$ threshold are located extraordinarily close to the ${\Lambda }_c(2625)$ and ${\Lambda }_c(2595)$, respectively, and hence they play totally different roles in each sector.

    hep-phPRD(2020)·32 citations
12. 12*

    Scalar dark matter coannihilating with a coloured fermion

    Simone Biondini🇳🇱 · Stefan Vogl🇩🇪

    We analyse the phenomenology of a simplified model for a real scalar dark matter candidate interacting with quarks via a coloured fermionic mediator. In the coannihilation regime, the dark matter abundance is controlled by the dynamics of the coloured fermions which can be significantly affected by non-perturbative effects. We employ a non-relativistic effective field theory approach which allows us to systematically treat the Sommerfeld effect and bound-state formation in the early Universe. The parameter space compatible with the dark matter relic abundance is confronted with direct, indirect and collider searches. A substantial part of the parameter space, with dark matter masses up to 18 TeV, is already excluded by XENON1T. Most of the remaining thermal relics can be probed by a future Darwin-like experiment, when taking properly into account the running of the relevant couplings for the direct detection processes.

    hep-phJHEP(2019)·41 citations
13. 13*

    Associated production of a Higgs boson decaying into bottom quarks and a weak vector boson decaying leptonically at NNLO in QCD

    R. Gauld🇳🇱 · A. Gehrmann-De Ridder🇨🇭 · E. W. N. Glover🇬🇧 · A. Huss🇨🇭 · I. Majer🇨🇭

    We present the calculation of next-to-next-to-leading order (NNLO) corrections in perturbative QCD for the production of a Higgs boson decaying into a pair of bottom quarks in association with a leptonically decaying weak vector boson: $\mathrm{pp}\to V\mathrm{H}+X\to \ell \bar{\ell }\mathrm{b}\bar{\mathrm{b}}+X$. We consider the corrections to both the production and decay sub-processes, retaining a fully differential description of the final state including off-shell propagators of the Higgs and vector boson. The calculation is carried out using the antenna subtraction formalism and is implemented in the NNLOJET framework. Clustering and identification of $\mathrm{b}$-jets is performed with the flavour-$k_t$ algorithm and results for fiducial cross sections and distributions are presented for the LHC at $\sqrt{s}=13\text{TeV}$. We assess the residual theory uncertainty by varying the production and decay scales independently and provide scale uncertainty bands in our results, yielding percent-level accurate predictions for observables in this Higgs production mode computed at NNLO. Confronting a naïve perturbative expansion of the cross section against the customary re-scaling procedure to a fixed branching ratio reveals that starting from NNLO, the latter could be inadequate in estimating missing higher-order effects through scale variations.

    hep-phhep-exJHEP(2019)·59 citations
14. 14*

    Compact star properties from an extended linear sigma model

    János Takátsy🇭🇺 · Péter Kovács🇭🇺 · Zsolt Szép🇭🇺 · György Wolf🇭🇺

    The equation of state provided by effective models of strongly interacting matter should comply with the restrictions imposed by current astrophysical observations of compact stars. Using the equation of state given by the (axial-)vector meson extended linear sigma model, we determine the mass-radius relation and study whether these restrictions are satisfied under the assumption that most of the star is filled with quark matter. We also compare the mass-radius sequence with those given by the equations of state of somewhat simpler models.

    hep-phastro-ph.HEnucl-thUniverse(2019)·6 citations
15. 15*

    Flavor changing neutral current decays $t\to cX$ ($X=\gamma ,g,Z,H$) and $t\to c\bar{\ell }\ell$ ($\ell =\mu ,\tau$) via scalar leptoquarks

    A. Bolaños🇲🇽 · R. Sánchez-Vélez🇲🇽 · G. Tavares-Velasco🇲🇽

    The flavor changing neutral current decays $t\to cX$ ($X=\gamma ,g,Z,H$) and $t\to c\bar{\ell }\ell$ ($\ell =\mu ,\tau$) are studied in a renormalizable scalar leptoquark (LQ) model with no proton decay, where a scalar $SU(2)$ doublet with hypercharge $Y=7/6$ is added to the standard model, yielding a non-chiral LQ ${\Omega }_{5/3}$. Analytical results for the one-loop (tree-level) contributions of a scalar LQ to the $f_i\to f_{j}X$ ($f_i\to f_j{\bar{f}}_m{f}_l$) decays, with $f_a=q_a,{\ell }_a$, are presented. We consider the scenario where ${\Omega }_{5/3}$ couples to the fermions of the second and third families, with its right- and left-handed couplings obeying ${\lambda }_R^{\ell u_i}/{\lambda }_L^{\ell u_i}=O(ϵ)$, where $ϵ$ parametrizes the relative size between these couplings. The allowed parameter space is then found via the current constraints on the muon $(g-2)$, the $\tau \to \mu \gamma$ decay, the LHC Higgs boson data, and the direct LQ searches at the LHC. For $m_{{\Omega }_{5/3}}=1$ TeV and $ϵ=10^{-3}$, we find that the $t\to cX$ branching ratios are of similar size and can be as large as $10^{-8}$ in a tiny area of the parameter space, whereas $\mathrm{Br}(t\to c\bar{\tau }\tau )$ [$\mathrm{Br}(t\to c\bar{\mu }\mu )$] can be up to $10^{-6}$ ($10^{-7}$).

    hep-phEPJC(2019)·12 citations
16. 16*

    Highly occupied gauge theories in 2+1 dimensions: self-similar attractor

    K. Boguslavski🇦🇹 · A. Kurkela🇨🇭 · T. Lappi🇫🇮 · J. Peuron🇮🇹

    Motivated by the boost-invariant Glasma state in the initial stages in heavy-ion collisions, we perform classical-statistical simulations of SU(2) gauge theory in 2+1 dimensional space-time both with and without a scalar field in the adjoint representation. We show that irrespective of the details of the initial condition, the far-from-equilibrium evolution of these highly occupied systems approaches a unique universal attractor at high momenta that is the same for the gauge and scalar sectors. We extract the scaling exponents and the form of the distribution function close to this non-thermal fixed point. We find that the dynamics are governed by an energy cascade to higher momenta with scaling exponents $\alpha =3\beta$ and $\beta =-1/5$. We argue that these values can be obtained from parametric estimates within kinetic theory indicating the dominance of small momentum transfer in the scattering processes. We also extract the Debye mass non-perturbatively from a longitudinally polarized correlator and observe an IR enhancement of the scalar correlation function for low momenta below the Debye mass.

    hep-phhep-latPRD(2019)·26 citations
17. 17*

    $Z^{\prime }$ Mediated WIMPs: Dead, Dying, or Soon to be Detected?

    Carlos Blanco🇺🇸 · Miguel Escudero🇬🇧 · Dan Hooper🇺🇸 · Samuel J. Witte🇪🇸

    Although weakly interacting massive particles (WIMPs) have long been among the most studied and theoretically attractive classes of candidates for the dark matter of our universe, the lack of their detection in direct detection and collider experiments has begun to dampen enthusiasm for this paradigm. In this study, we set out to appraise the status of the WIMP paradigm, focusing on the case of dark matter candidates that interact with the Standard Model through a new gauge boson. After considering a wide range of $Z^{\prime }$ mediated dark matter models, we quantitatively evaluate the fraction of the parameter space that has been excluded by existing experiments, and that is projected to fall within the reach of future direct detection experiments. Despite the existence of stringent constraints, we find that a sizable fraction of this parameter space remains viable. More specifically, if the dark matter is a Majorana fermion, we find that an order one fraction of the parameter space is in many cases untested by current experiments. Future direct detection experiments with sensitivity near the irreducible neutrino floor will be able to test a significant fraction of the currently viable parameter space, providing considerable motivation for the next generation of direct detection experiments.

    hep-phastro-ph.COhep-exJCAP(2019)·60 citations
18. 18*

    Exotic decays of top partners with charge 5/3: bounds and opportunities

    Ke-Pan Xie🇰🇷 · Giacomo Cacciapaglia🇫🇷 · Thomas Flacke🇰🇷

    Exotic decays of top partners in new bosons are the norm in realistic models of a composite Higgs. We focus on the custodial charge-$5/3$ partner, which normally decays exclusively into $t{W}^{+}$. The new channels include a colour-sextet, $X_{5/3}\to \bar{b}{\pi }_6$, as well as singly and doubly charged scalars, $X_{5/3}\to t{\varphi }^{+}$, $b{\varphi }^{++}$. We use existing same-sign lepton searches to show that the new final states are constrained at the same level as the standard one. At the same time, exotic final states also offer opportunities for improvement: examples include a hard photon in $X_{5/3}\to t{\varphi }^{+}\to t{W}^{+}\gamma$ decays, and top-rich channels which arise in several exotic $X_{5/3}$ decays.

    hep-phJHEP(2019)·40 citations
19. 19*

    Probing Transverse-Momentum Distributions With Groomed Jets

    Daniel Gutierrez-Reyes🇪🇸 · Yiannis Makris🇺🇸 · Varun Vaidya🇺🇸 · Ignazio Scimemi🇪🇸 · Lorenzo Zoppi🇳🇱

    We present the transverse momentum spectrum of groomed jets in di-jet events for $e^{+}{e}^{-}$ collisions and semi-inclusive deep inelastic scattering (SIDIS). The jets are groomed using a soft-drop grooming algorithm which helps in mitigating effects of non-global logarithms and underlying event. At the same time, by reducing the final state hadronization effects, it provides a clean access to the non-perturbative part of the evolution of transverse momentum dependent (TMD) distributions. In SIDIS experiments we look at the transverse momentum of the groomed jet measured w.r.t. the incoming hadron in the Breit frame. Because the final state hadronization effects are significantly reduced, the SIDIS case allows to probe the TMD parton distribution functions. We discuss the sources of non-perturbative effects in the low transverse momentum region including novel (but small) effects that arise due to grooming. We derive a factorization theorem within SCET and resum any large logarithm in the measured transverse momentum up to NNLL accuracy using the $\zeta$-prescription as implemented in the artemide package and provide a comparison with simulations.

    hep-phhep-exnucl-exnucl-thJHEP(2019)·57 citations
20. 20*

    Higgs Quark Flavor Violation: Simplified Models and Status of General Two-Higgs-Doublet Model

    Juan Herrero-Garcia🇮🇹 · Miguel Nebot🇵🇹 · Filip Rajec🇦🇺 · Martin White🇦🇺 · Anthony G. Williams🇦🇺

    We study quark flavor violating interactions mediated by the Higgs boson $h$. We consider observables involving a third generation quark, of both the up and the down quark sectors, like $h\to bs$ and $t\to ch$. Using an effective field theory approach we systematically list all the possible tree-level ultraviolet completions, which comprise models with vector-like quarks and/or extra scalars. We provide upper bounds on the flavor violating transitions allowed by current limits stemming from low energy processes, such as meson mixing and $b\to s\gamma$. We find that scenarios with vector-like quarks always have very suppressed flavor-violating transitions, while a general two Higgs doublet model may have a sizeable rate. To study the latter case in detail, we perform a full numerical simulation taking into account all relevant theoretical and phenomenological constraints. Our results show that $\mathrm{BR}(t\to ch)$ [$\mathrm{BR}(h\to bs)$] are still allowed at the subpercent [percent] level, which are being [may be] explored at the LHC [future colliders]. Finally, we have found that the mild mass-splitting discrepancy with respect to the SM in the $B_s$ meson system can be accommodated in the Two-Higgs-Doublet Model. If confirmed, it yields the prediction $\mathrm{BR}(h\to bs)\simeq 10^{-4}$, if the new contribution to the mass-splitting is dominated by tree-level Higgs boson exchange.

    hep-phJHEP(2020)·16 citations
21. 21*

    Correlations between azimuthal anisotropy Fourier harmonics in PbPb collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=2.76$ TeV in the HYDJET++ and AMPT models

    M. Dordevic🇷🇸 · J. Milosevic🇷🇸 · L. Nadderd🇷🇸 · M. Stojanovic🇷🇸 · F. Wang🇺🇸 · X. Zhu🇨🇳

    Correlations between azimuthal anisotropy Fourier harmonics $v_n$ ($n=2,3,4$) are studied using the events from PbPb collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=2.76$ TeV generated by the HYDJET++ and AMPT models, and compared to the corresponding experimental results obtained by the ATLAS Collaboration. The Fourier harmonics $v_n$ are measured over a wide centrality range using the two-particle azimuthal correlation method. The slopes of the $v_2$--$v_3$ correlation from both models are in a good agreement with the ATLAS data. The HYDJET++ model predicts a stronger slope for the $v_2$--$v_4$ and $v_3$--$v_4$ correlations than the ones experimentally measured, while the results from the AMPT model are in a rather good agreement with the experimental results. In contrast to the HYDJET++ predictions, the AMPT model predicts a boomerang-like shape in the structure of the correlations as found in the experimental data.

    ↳ nucl-thhep-phPRC(2020)·7 citations
22. 22*

    On the Cottingham formula and the electromagnetic contribution to the proton-neutron mass splitting

    Andre Walker-Loud🇺🇸

    The excess mass of the neutron over the proton arises from two sources within the Standard Model, electromagnetism and the splitting of the down and up quark masses. The Cottingham Formula provides a means of determining the QED corrections from the forward Compton Amplitude, but this is challenged by the need for a subtraction function and the mixing of the QED and QCD (electro-weak) effects. I review the present understanding of the Cottingham Formula, including a discussion on the development of the formula, its renormalization which induces the mixing of QED and QCD effects, and the necessary modeling of the subtraction function that must be done to arrive a numerical prediction. I summarize the Regge Model originally proposed by Gasser and Leutwyler and I also review the proposed model by Walker-Loud, Carlson and Miller, which is an interpolation function between the low and high $Q^2$ regimes, both of which are anchored by rigorous theoretical underpinnings, for which I argue a more reliable theoretical uncertainty estimate can be obtained.

    ↳ nucl-thhep-lathep-phPoS(2019)·10 citations
23. 23*

    Probing observational bounds on scalar-tensor theories from standard sirens

    Rocco D'Agostino🇮🇹 · Rafael C. Nunes🇧🇷

    Standard sirens are the gravitational wave (GW) analog of the astronomical standard candles, and can provide powerful information about the dynamics of the Universe. In this work, we simulate a catalog with 1000 standard siren events from binary neutron star mergers, within the sensitivity predicted for the third generation of the ground GW detector called Einstein telescope. After correctly modifying the propagation of GWs as input to generate the catalog, we apply our mock data set on scalar-tensor theories where the speed of GW propagation is equal to the speed of light. As a first application, we find new observational bounds on the running of the Planck mass, when considering appropriate values within the stability condition of the theory, and we discuss some consequences on the amplitude of the running of the Planck mass. In the second part, we combine our simulated standard sirens catalog with other geometric cosmological tests (Supernovae Ia and cosmic chronometers measurements) to constrain the Hu-Sawicki $f(R)$ gravity model. We thus find new and non-null deviations from the standard $\Lambda$CDM model, showing that in the future the $f(R)$ gravity can be tested up to 95\% confidence level. The results obtained here show that the statistical accuracy achievable by future ground based GW observations, mainly with the ET detector (and planed detectors with a similar sensitivity), can provide strong observational bounds on modified gravity theories.

    ↳ gr-qcastro-ph.COhep-phPRD(2019)·104 citations
24. 24*

    Evaporating primordial black holes as varying dark energy

    Savvas Nesseris🇪🇸 · Domenico Sapone🇨🇱 · Spyros Sypsas🇹🇭

    If light enough primordial black holes (PBH) account for dark matter, then its density decreases with time as they lose mass via Hawking radiation. We show that this time-dependence of the matter density can be formulated as an equivalent $w(z)$ dark energy model and we study its implications on the expansion history. Using our approach and comparing with the latest cosmological data, including the supernovae type Ia, Baryon Acoustic Oscillations, Cosmic Microwave Background and the Hubble expansion H(z) data, we place observational constraints on the PBH model. We find that it is statistically consistent with $\Lambda$CDM according to the AIC statistical tool. Furthermore, we entertain the idea of having a population of ultra-light PBHs, decaying around neutrino decoupling, on top of the dark matter fluid and show how this offers a natural dark matter-radiation coupling altering the expansion history of the Universe and alleviating the $H_0$ tension.

    ↳ astro-ph.COgr-qchep-phPhys.Dark Univ.(2020)·37 citations
25. 25*

    Effective interactions in Ricci-Based Gravity models below the non-metricity scale

    Adria Delhom🇪🇸 · Victor Miralles🇪🇸 · Ana Peñuelas🇪🇸

    We show how minimally-coupled matter fields of arbitrary spin, when coupled to Ricci-Based Gravity theories, develop non-trivial effective interactions that can be treated perturbatively only below a characteristic high-energy scale ${\Lambda }_Q$. Our results generalize to arbitrary matter fields those recently obtained for spin 1/2 fields in \cite{Latorre:2017uve}. We then use this interactions to set bounds on the high-energy scale ${\Lambda }_Q$ that controls departures of Ricci-Based Gravity theories from General Relativity. Particularly, for Eddington-inspired Born-Infeld gravity we obtain the strong bound $|\kappa |<3.5\times 10^{-14}{\text{ m}}^5{\text{kg}}^{-1}{\text{s}}^{-2}$.

    ↳ hep-thgr-qchep-phEPJC(2020)·34 citations
26. 26*

    Higher Spin Supersymmetry at the Cosmological Collider: Sculpting SUSY Rilles in the CMB

    Stephon Alexander🇺🇸 · S. James Gates Jr.🇺🇸 · Leah Jenks🇺🇸 · K. Koutrolikos🇺🇸 · Evan McDonough🇺🇸

    We study the imprint of higher spin supermultiplets on cosmological correlators, namely the non-Gaussianity of the cosmic microwave background. Supersymmetry is used as a guide to introduce the contribution of fermionic higher spin particles, which have been neglected thus far in the literature. This necessarily introduces more than just a single additional fermionic superpartner, since the spectrum of massive, higher spin supermultiplets includes two propagating higher spin bosons and two propagating higher spin fermions, which all contribute to the three point function. As an example we consider the half-integer superspin $\text{Y}=s+1/2$ supermultiplet, which includes particles of spin values $j=s+1,j=s+1/2,j=s+1/2$ and $j=s$. We compute the curvature perturbation 3-point function for higher spin particle exchange and find that the known $P_s(\cos \theta )$ angular dependence is accompanied by superpartner contributions that scale as $P_{s+1}(\cos \theta )$ and ${\sum }_m{P}_s^m(\cos \theta )$, with $P_s$ and $P_s^m$ defined as the Legendre and Associated Legendre polynomials respectively. We also compute the tensor-scalar-scalar 3-point function, and find a complicated angular dependence as an integral over products of Legendre and associated Legendre polynomials.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2019)·85 citations
27. 27*

    A Goldilocks Higgs

    Nemanja Kaloper🇺🇸 · Alexander Westphal🇩🇪

    The Higgs could couple to a topological 4-form sector which yields a complex vacuum structure. In general such couplings could lead to direct CP violation in the Higgs sector. In many of the Higgs vacua electroweak symmetry is unbroken. In just as many it breaks when the 4-form flux is large enough. For a fixed value of flux, the symmetry breaking vacua have a smaller vacuum energy than the symmetric ones, where the difference is quantized because it is set by the $4$-form flux. This leads to the possibility that there is a value of the 4-form flux for any UV contributions to the Higgs {\it vev} that automatically cancels it down to the right value, $\sim$ TeV, if the 4-form charges are quantized in the units of the electroweak scale. This would still leave the cosmological constant which could be selected anthropically.

    ↳ hep-thastro-ph.COgr-qchep-phPLB(2020)·29 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.