Tue·Jan 1, 2019Tuesday·January 1, 2019

1. 01*

   Six Top Messages of New Physics at the LHC

   Huayong Han🇨🇳 · Li Huang · Teng Ma🇨🇳 · Jing Shu🇨🇳 · Tim M.P. Tait🇺🇸 · Yongcheng Wu🇨🇦

   Six top signatures provide a novel probe of new physics. We discuss production of six top quarks as the decay products of a pair of top partners in the setting of a composite Higgs model, and argue that the six top signal may generically provide one of the first final states to show a discrepancy. We construct an analysis based on quantities such as $H_T$ and the numbers of jets which are tagged as boosted tops, $W$s, or containing $b$-tags, and show that the LHC with 3~ab${}^{-1}$ can discover top partners with masses up to around 2.5 TeV in the six top signature.

   hep-phJHEP(2019)·32 citations
2. 02*

   Trimaximal Neutrino Mixing from Modular A4 Invariance with Residual Symmetries

   P.P. Novichkov🇮🇹 · S.T. Petcov🇮🇹 · M. Tanimoto🇯🇵

   We construct phenomenologically viable models of lepton masses and mixing based on modular $A_4$ invariance broken to residual symmetries ${\mathbb{Z}}_3^T$ or ${\mathbb{Z}}_3^{ST}$ and ${\mathbb{Z}}_2^S$ respectively in the charged lepton and neutrino sectors. In these models the neutrino mixing matrix is of trimaximal mixing form. In addition to successfully describing the charged lepton masses, neutrino mass-squared differences and the atmospheric and reactor neutrino mixing angles ${\theta }_{23}$ and ${\theta }_{13}$, these models predict the values of the lightest neutrino mass (i.e., the absolute neutrino mass scale), of the Dirac and Majorana CP violation(CPV) phases, as well as the existence of specific correlations between i) the values of the solar neutrino mixing angle ${\theta }_{12}$ and the angle ${\theta }_{13}$ (which determines ${\theta }_{12}$), ii) the values of the Dirac CPV phase $\delta$ and of the angles ${\theta }_{23}$ and ${\theta }_{13}$, iii) the sum of the neutrino masses and ${\theta }_{23}$, and iv) between the two Majorana phases.

   hep-phPLB(2019)·209 citations
3. 03*

   Probing Two types of Gluon Jets at LHC

   Y. M. Cho🇰🇷 · Franklin H. Cho🇨🇦 · Pengming Zhang🇨🇳

   We propose a simple way to test the Abelian decomposition of QCD, the existence of two types of gluons, experimentally at LHC. The Abelian decomposition decomposes the gluons to the color neutral neurons and colored chromons gauge independently. This refines the Feynman diagram in a way that the color conservation is explicit, and generalizes the quark model to the quark and chromon model. We predict that the neuron jet has the color factor 3/4 and has a sharpest jet radius and smallest particle multiplicity, while the chromon jet with the color factor 9/4 remains the broadest jet. Moreover, the neuron jet has a distinct color flow which forms an ideal color dipole, while the quark and chromon jets have distorted dipole pattern.

   hep-ph2 citations
4. 04*

   Higgs Vacuum Stability with Vector-like Fermions

   Shrihari Gopalakrishna🇮🇳 · Arunprasath Velusamy🇮🇳

   We present the effects of vector-like fermions (VLF) on the stability of the Higgs electroweak vacuum, using the renormalization group improved Higgs effective potential. We review the calculation of the one-loop beta-functions of the standard model couplings, paying particular attention to the fermion contributions. From this, we derive the VLF contributions to the beta-functions. We also include the significant two-loop contributions to the beta-functions. Using these beta-functions we determine the scale at which the effective Higgs quartic-coupling becomes zero and goes negative, signaling vacuum instability. We find that for certain VLF masses and Yukawa couplings, the Higgs quartic stays positive for field values all the way up to the Planck scale, implying that the meta-stable vacuum of the standard model can be rendered absolutely stable if VLFs are present with certain parameters. For other values of VLF parameters, the Higgs vacuum is metastable as in the standard model. For cases where the vacuum is metastable, we compute the probability of quantum tunneling from the false electroweak vacuum into a deeper true vacuum in our Hubble volume by numerically solving for the bounce configuration in Euclidean space-time and computing the bounce action for it. We compare our numerical solution with the analytical approximation for the bounce action commonly used in the literature and comment on when the latter may be used.

   hep-phPRD(2019)·40 citations
5. 05*

   Resonant leptogenesis at TeV-scale and neutrinoless double beta decay

   Takehiko Asaka🇯🇵 · Takahiro Yoshida🇯🇵

   We investigate a resonant leptogenesis scenario by quasi-degenerate right-handed neutrinos which have TeV-scale masses. Especially, we consider the case when two right-handed neutrinos are responsible to leptogenesis and the seesaw mechanism for active neutrino masses, and assume that the CP violation occurs only in the mixing matrix of active neutrinos. In this case the sign of the baryon asymmetry depends on the Dirac and Majorana CP phases as well as the mixing angle of the right-handed neutrinos. It is shown how the yield of the baryon asymmetry correlates with these parameters. In addition, we find that the effective neutrino mass in the neutrinoless double beta decay receives an additional constraint in order to account for the observed baryon asymmetry depending on the masses and mixing angle of right-handed neutrinos.

   hep-phastro-ph.COhep-exJHEP(2019)·24 citations
6. 06*

   Prompt atmospheric neutrinos in the quark-gluon string model

   S. I. Sinegovsky🇷🇺 · M. N. Sorokovikov (Joint Institute for Nuclear Research & Irkutsk State University)🇷🇺

   We calculate the atmospheric flux of prompt neutrinos, produced in decays of the charmed particles at energies beyond 1 TeV. Cross sections of the $D$-mesons and ${\Lambda }_c^{+}$ baryons production in pA and $\pi$A collisions are calculated in the phenomenological quark-gluon string model (QGSM) which is updated using of the recent measurements of cross sections of the charmed meson production in the LHC experiments. A new estimate of the prompt atmospheric neutrino flux is obtained and compared with the limit of the IceCube experiment as well as with predictions of other charm production models.

   hep-phastro-ph.HEEPJC(2020)·10 citations
7. 07*

   Particle Yields and Ratios within Equilibrium and Non-Equilibrium Statistics

   Abdel Nasser Tawfik (Nile U., Cairo & Egyptian Ctr. Theor. Phys., Cairo & WLCAPP, Cairo)🇪🇬 · Hayam Yassin🇪🇬 · Eman R. Abo Elyazeed (Ain Shams U., Cairo & Egyptian Ctr. Theor. Phys., Cairo & WLCAPP, Cairo)🇪🇬

   In characterizing the yields and ratios various of well identified particles in the ALICE experiment, we utilize extensive {\it additive} thermal approaches, to which various missing states of the hadron resonances are taken into consideration, as well. Despite some non-equilibrium conditions that are slightly driving this statistical approach away from equilibrium, the approaches are and remain additive and extensive. Besides van der Waals repulsive interactions (assuming that the gas constituents are no longer point-like, i.e. finite-volume corrections taken into consideration), finite pion chemical potentials as well as perturbations to the light and strange quark occupation factors are taken into account. When confronting our calculations to the ALICE measurements, we conclude that the proposed conditions for various aspects deriving the system out of equilibrium notably improve the reproduction of the experimental results, i.e. improving the statistical fits, especially the finite pion chemical potential. This points out to the great role that the non-equilibrium pion production would play, and the contributions that the hadron resonance missing states come up with, even when the principles of statistical extensivity and additivity aren't violated. These results seem to propose revising the conclusions propagated by most of the field, that the produced particles quickly reach a state of local equilibrium leading to a collective expansion often described by fluid dynamics. This situation seems not remaining restrictively valid, at very large collision energies.

   hep-phnucl-thEPL(2019)·3 citations
8. 08*

   Three body radiative decay $B_s\to \varphi {\bar{K}}^0\gamma$ in the PQCD approach

   Zhi-Qing Zhang🇨🇳 · Hongxia Guo🇨🇳

   We study the three body radiative decay $B_s\to \varphi {\bar{K}}^0\gamma$ by introducing the $\varphi K$ pair distribution amplitudes (DAs) in the perturbative QCD approach. This nonperturbative inputs, the two meson DAs, is very important to simplify the calculations. Besides the dominant electromagnetic penguin operator $O_{7\gamma }$, the subleading contributions from chromomagnetic penguin operator $O_{8g}$, quark-loop corrections and annihilation type amplitudes are also considered. We find that the branching ratio for the decay $B_s\to \varphi {\bar{K}}^0\gamma$ is about $(9.26_{-1.61-3.86-0.49}^{+1.79+3.12+0.64})\times 10^{-8}$, which is much smaller compared with that for the decay $B^0\to \varphi K^0\gamma$. It is mainly because that the former decay induces by $b\to d\gamma$ with small CKM matrix element being proportional to ${\lambda }^3$. The prediction for the direct CP asymmetry is $A_{CP}^{dir}(B_s\to \varphi {\bar{K}}^0\gamma )=(-4.1_{-0.6-1.2-0.1}^{+0.4+1.7+0.2})\%$, which is well consistent with the result from the U-spin symmetry approach. we also predict the $B_s\to \varphi {\bar{K}}^0\gamma$ decay spectrum, which exhibits a maximu at the $\varphi K$ invariant masss around 1.95 GeV.

   hep-phEPJC(2019)·4 citations
9. 09*

   Boosting Assisted Annihilation for a Cosmologically Safe MeV Scale Dark Matter

   Ujjal Kumar Dey🇰🇷 · Tarak Nath Maity🇮🇳 · Tirtha Sankar Ray🇮🇳

   Assisted annihilation generates thermal sub-GeV dark matter through a novel annihilation between a pair of dark matter and standard-model-like states, called the "assister". We show that, depending on the mass hierarchy between the assister and dark matter, there can be either a suppression or a boost of the effective cross section. This augmentation enables the possibility of $\mathcal{O}(100)$ MeV scale dark matter with perturbative coupling that saturates the relic density estimates while being relatively insulated from cosmological constraints like big bang nucleosynthesis and cosmic microwave background.

   hep-phastro-ph.COPRD(2019)·12 citations
10. 10*

    New ultraviolet operators in supersymmetric SO(10) GUT and consistent cosmology

    Piyali Banerjee🇮🇳 · Urjit A. Yajnik🇮🇳

    We consider the minimal supersymmetric grand unified model (MSGUT) based on the group $\mathrm{SO}(10)$, and study conditions leading to possible domain wall (DW) formation. It has been shown earlier that the supersymmetry preserving vacuum expectation values (vev's) get mapped to distinct but degenerate set of vev's under action of $D$ parity, leading to formation of domain walls as topological pseudo-defects. The metastability of such walls can make them relatively long lived and contradict standard cosmology. Thus we are led to consider adding a nonrenormalisable Planck scale suppressed operator, that breaks $\mathrm{SO}(10)$ symmetry but preserves Standard Model symmetry. For a large range of right handed breaking scales $M_R$, this is shown to give rise to the required pressure difference to remove the domain walls without conflicting with consistent big bang nucleosynthesis (BBN) while avoiding gravitino overproduction. However, if the walls persist till the onset of weak (thermal) inflation, then a low $\sim 10-100$ TeV $M_R$ becomes problematic.

    hep-phastro-ph.COhep-thPRD(2020)·6 citations
11. 11*

    Effective Field Theories in R_xi gauges

    M. Misiak🇵🇱 · M. Paraskevas🇬🇷 · J. Rosiek🇵🇱 · K. Suxho🇬🇷 · B. Zglinicki🇵🇱

    In effective quantum field theories, higher dimensional operators can affect the canonical normalization of kinetic terms at tree level. These contributions for scalars and gauge bosons should be carefully included in the gauge fixing procedure, in order to end up with a convenient set of Feynman rules. We develop such a setup for the linear R_xi-gauges. It involves a suitable reduction of the operator basis, a generalized gauge fixing term, and a corresponding ghost sector. Our approach extends previous results for the dimension-six Standard Model Effective Field Theory to a generic class of effective theories with operators of arbitrary dimension.

    hep-phhep-thJHEP(2019)·20 citations
12. 12*

    Early time dynamics and hard probes in heavy-ion collisions

    S. Schlichting🇩🇪

    We present an overview of the current state of understanding of the early time dynamics of high-energy heavy-ion collisions, emphasizing recent developments and connections between the physics of the initial state and that of hard probes in heavy-ion collisions. Based on a weak-coupling description, we first establish a microscopic picture of the early time dynamics and equilibration process and subsequently discuss their macroscopic manifestations along with a novel macroscopic description of the pre-equilibrium phase. Some phenomenological consequences concerning the role of the pre-equilibrium phase in large (AA) and small (pp/pA) collision systems are briefly discussed along with open questions and opportunities for future improvements.

    hep-phnucl-thPoS(2019)·2 citations
13. 13*

    Jet fragmentation in a QCD medium: Universal quark/gluon ration and Wave turbulence

    Y. Mehtar-Tani🇺🇸 · S. Schlichting🇩🇪

    We calculate the evolution of a jet shower due to medium induced splittings in the deep LPM regime. Due to the characteristic energy dependence of the formation time $t_{\mathrm{form}}(\omega )=\sqrt{\omega /\hat{\bar{q}}}$, the radiative break-up process exhibits turbulent characteristics, allowing for analytic predictions of various inclusive properties of the medium induced cascade in an inertial range of energies $T\ll \omega \ll E$, where $E$ is the energy of the jet and $T$ is the temperature of the medium.

    hep-phnucl-thPoS(2018)·0 citations
14. 14*

    Effects of Violation of Equivalence Principle on UHE Neutrinos at IceCube in 4 Flavour Scenario

    Madhurima Pandey🇮🇳

    If weak equivalence principle is violated then different types of neutrinos would couple differently with gravity and that may produce a gravity induced oscillation for the neutrinos of different flavour. We explore here the possibility that very small violation of the principle of weak equivalence (VEP) can be probed by ultra high energy neutrinos from distant astrophysical sources. The very long baseline length and the ultra high energies of such neutrinos could be helpful to probe very small VEP. We consider a 4-flavour neutrino scenario (3 active + 1 sterile) with both mass-flavour and gravity induced oscillations and compare the detection signatures for these neutrinos (muon tracks and shower events) with and without gravity induced oscillations at a kilometer scale detector such as IceCube. We find that even very small VEP ($\sim 10^{-42}$) can considerably affect the detected muon yield produced by UHE neutrinos from distant Gamma Ray Bursts (GRBs)

    hep-ph0 citations
15. 15*

    Gauge field theories with Lorentz-violating operators of arbitrary dimension

    Alan Kostelecky🇺🇸 · Zonghao Li🇺🇸

    The classification of Lorentz- and CPT-violating operators in nonabelian gauge field theories is performed. We construct all gauge-invariant terms describing propagation and interaction in the action for fermions and gauge fields. Restrictions to the abelian, Lorentz-invariant, and isotropic limits are presented. We provide two illustrative applications of the results to quantum electrodynamics and quantum chromodynamics. First constraints on nonlinear Lorentz-violating effects in electrodynamics are obtained using data from experiments on photon-photon scattering, and corrections from nonminimal Lorentz and CPT violation to the cross section for deep inelastic scattering are derived.

    hep-phPRD(2019)·140 citations
16. 16*

    Peccei-Quinn Symmetry and Nucleon Decay in Renormalizable SUSY SO(10)

    K.S. Babu🇺🇸 · Takeshi Fukuyama🇯🇵 · Saki Khan🇺🇸 · Shaikh Saad🇺🇸

    We suggest simple ways of implementing Peccei-Quinn (PQ) symmetry to solve the strong CP problem in renormalizable SUSY $SO(10)$ models with a minimal Yukawa sector. Realistic fermion mass generation requires that a second pair of Higgs doublets survive down to the PQ scale. We show how unification of gauge couplings can be achieved in this context. Higgsino mediated proton decay rate is strongly suppressed by a factor of $(M_{\mathrm{PQ}}/M_{\mathrm{GUT}}{)}^2$, which enables all SUSY particles to have masses of order TeV. With TeV scale SUSY spectrum, $p\to \overline{\nu }{K}^{+}$ decay rate is expected to be in the observable range. Lepton flavor violating processes $\mu \to e\gamma$ decay and $\mu -e$ conversion in nuclei, induced by the Dirac neutrino Yukawa couplings, are found to be within reach of forthcoming experiments.

    hep-phJHEP(2019)·24 citations
17. 17*

    GUT-inspired MSSM in light of muon $g-2$ and LHC results at $\sqrt{s}=13$ TeV

    Hieu Minh Tran🇻🇳 · Huong Thu Nguyen🇻🇳

    The recent results of the LHC search for electroweak production of supersymmetric (SUSY) particles at $\sqrt{s}=13$ TeV have shown improved lower limits for their masses. In addition, the projected experiment E989 will be able to measure the muon anomalous magnetic moment precisely so that the experimental uncertainty can be reduced by a factor of four. It was pointed out that if the center value of the muon $g-2$ remains unchanged the deviation between the standard model (SM) prediction and the experimental value will be as large as 7.0$\sigma$. Such a large deviation will be solid evidence for new physics beyond the SM. Motivated by these results, we investigate the minimal SUSY extension of the SM with universal gaugino masses at the grand unified scale in the light of the muon $g-2$ and the updated LHC constraints. The squarks are assumed to be heavy and decoupled from physics at low energy scales to resemble the SM-like Higgs boson mass of 125 GeV and other bounds for squark masses at the LHC. We have pinned down allowed windows for the lightest neutralino and the smuon masses as well as other input parameters relevant to the light SUSY sector. The expected results of the E989 experiment play a crucial role in narrowing these windows. The viability of the model for small mass regions can be tested at the LHC Run 3 and the High Luminosity LHC in the near future.

    hep-phPRD(2019)·31 citations
18. 18*

    Constraints from a many-body method on spin-independent dark matter scattering off electrons using data from germanium and xenon detectors

    Mukesh K. Pandey🇹🇼 · Lakhwinder Singh🇹🇼 · Chih-Pan Wu🇹🇼 · Jiunn-Wei Chen🇹🇼 · Hsin-Chang Chi🇹🇼 · Chung-Chun Hsieh🇹🇼 · C.-P. Liu🇹🇼 · Henry T. Wong🇹🇼

    Scattering of light dark matter (LDM) particles with atomic electrons is studied in the context of effective field theory. Contact and long-range interactions between dark matter and an electron are both considered. A state-of-the-art many-body method is used to evaluate the spin-independent atomic ionization cross sections of LDM-electron scattering, with an estimated error about 20%. New upper limits are derived on parameter space spanned by LDM mass and effective coupling strengths using data from the CDMSlite, XENON10, XENON100, and XENON1T experiments. Comparison with existing calculations shows the importance of atomic structure. Two aspects particularly important are relativistic effect for inner-shell ionization and final-state free electron wave function which sensitively depends on the underlying atomic approaches.

    hep-phhep-exPRD(2020)·29 citations
19. 19*

    Mesonic Condensation in Isospin Matter under Rotation

    Hui Zhang🇨🇳 · Defu Hou🇨🇳 · Jinfeng Liao🇺🇸

    We investigate the mesonic condensation in isospin matter under rotation. Using the two-flavor NJL effective model under the presence of global rotation, we demonstrate two important effects of the rotation on its phase structure: a rotational suppression of the scalar-channel condensates, in particular the pion condensation region; and a rotational enhancement of the rho condensation region with vector-channel condensate. A new phase diagram for isospin matter under rotation is mapped out on the $\omega -{\mu }_I$ plane where three distinctive phases, corresponding to $\sigma$, $\pi$, $\rho$ dominated regions respectively, are separated by a second-order line at low isospin chemical potential and a first-order line at high rotation which are further connected at a tri-critical point.

    hep-phnucl-thCPC(2020)·54 citations
20. 20*

    $B\to K_2^{\ast }(1430){\ell }^{+}{\ell }^{-}$ distributions in Standard Model at large recoil

    Diganta Das🇮🇳 · Bharti Kindra🇮🇳 · Girish Kumar🇮🇳 · Namit Mahajan🇮🇳

    We study the rare decay $B\to K_2^{\ast }(1430)(\to K\pi ){\ell }^{+}{\ell }^{-}$ in the Standard Model and beyond. Working in the transversity basis, we exploit the relations between the heavy-to-light form factors in the limit of heavy quark ($m_b\to \infty$) and large energy ($E_{K_2^{\ast }}\to \infty$) of the $K_2^{\ast }$ meson. This allows us to construct observables where at leading order in ${\Lambda }_{\mathrm{QCD}}/m_b$ and ${\alpha }_s$ the form factor dependence involving the $B\to K_2^{\ast }$ transitions cancels. Higher order corrections are systematically incorporated in the numerical analysis. In the Standard Model the decay has a sizable branching ratio and therefore a large number of events can be expected at LHCb. Going beyond the Standard Model, we explore the implications of the global fit to presently available $b\to s{\ell }^{+}{\ell }^{-}$ data on the $B\to K_2^{\ast }{\ell }^{+}{\ell }^{-}$ observables.

    hep-phhep-exPRD(2019)·17 citations
21. 21*

    Five-loop contributions to low-N non-singlet anomalous dimensions in QCD

    F. Herzog (Nikhef, Amsterdam)🇳🇱 · S. Moch (Hamburg U., Inst. Theor. Phys. II)🇩🇪 · B. Ruijl (Zurich, ETH)🇨🇭 · T. Ueda (Seikei U.)🇯🇵 · J.A. M. Vermaseren (Nikhef, Amsterdam)🇳🇱 · A. Vogt (Liverpool U., Dept. Math)🇬🇧

    We present the first calculations of next-to-next-to-next-to-next-to-leading order (N^4LO) contributions to anomalous dimensions of spin-N twist-2 operators in perturbative QCD. Specifically, we have obtained the respective non-singlet quark-quark anomalous dimensions at N=2 and N=3 to the fifth order in the strong coupling alpha_s. These results set the scale for the N^4LO contributions to the evolution of the non-singlet quark distributions of hadrons outside the small-x region, and facilitate a first approximate determination of the five-loop cusp anomalous dimension. While the N^4LO coefficients are larger than expected from the lower-order results, their inclusion stabilizes the perturbative expansions for three or more light flavours at a sub-percent accuracy for alpha_s < 0.3.

    hep-phPLB(2019)·101 citations
22. 22*

    Exploring the prominent channel: Charged Higgs pair production in supersymmetric Two-parameter Non-Universal Higgs Model

    Nasuf Sonmez🇹🇷

    In this study, the charged Higgs pair production is calculated in the context of the supersymmetry at a $\gamma \gamma$-collider. The channel is explored in Two-parameter Non-Universal Higgs Model where the model provides relatively light neutral and charged Higgs bosons. The computation is extended to one loop-level, and the divergence arising in the loop-diagrams are cured with the radiative photon correction. The production rate of the charged Higgs pair reaches up to ${\hat{\sigma }}_{\text{UU}}^{\text{LO+NLO}}=121\text{ fb}$ at $\sqrt{\hat{s}}=635\text{ GeV}$. The analysis of the cross-section is also given varying the parameters $m_A$ and $\tan \beta$. The total convoluted cross-section with the photon luminosity in an $e^{+}{e}^{-}$ machine is calculated as a function of the center-of-mass energy up to $1\text{ TeV}$, and it gets up to $42\text{ fb}$ at $\sqrt{s}=900\text{ GeV}$ depending on the polarization of the initial electron and laser photon.

    hep-phNPB(2020)·2 citations
23. 23*

    Anomalous EDGES 21-cm Signal and Moduli Dominated Era

    Mansi Dhuria🇮🇳

    The EDGES collaboration has recently reported the detection of an unexpectedly stronger absorption signal in the global 21-cm spectrum around cosmic red-shift z = 17, resulting in the significant cooling of the primordial gas. The cooling of the gas can be expected to occur by considering the scattering off the baryons by a small fraction of DM carrying a tiny electromagnetic charge (milli-charged DM). However, it turns out the energy density of milli-charged DM obtained by considering thermal annihilation through massless photons will get overproduced in the range of parameters allowed by 21-cm line signal, if there are no new force carriers etc. In this study, we argue that the milli-charged DM particles might get decoupled during matter domination, in case there are moduli present in the theory. Therefore we estimated the value of relic abundance of milli-charged DM by taking into account an early matter dominated era. We found that for the value of modulus mass around m_{\Phi} ~ 10^6TeV, the milli-charged DM particles could actually yield the desired fraction of DM particles for the values of charge and DM required to explain the 21-cm signal. Thus, the problem of an overproduction of the milli-charged DM density in the desirable range of mass and charge of DM can be evaded by considering an early moduli/matter dominated era.

    hep-phPRD(2019)·3 citations
24. 24*

    NLOX, a one-loop provider for Standard Model processes

    Steve Honeywell🇺🇸 · Seth Quackenbush🇺🇸 · Laura Reina🇺🇸 · Christian Reuschle🇺🇸

    NLOX is a computer program for calculations in high-energy particle physics. It provides fully renormalized scattering matrix elements in the Standard Model of particle physics, up to one-loop accuracy for all possible coupling-power combinations in the strong and electroweak couplings, and for processes with up to six external particles.

    hep-phComput.Phys.Commun.(2020)·26 citations
25. 25*

    Probing the seesaw mechanism at the 250 GeV ILC

    Arindam Das🇯🇵 · Nobuchika Okada🇺🇸 · Satomi Okada🇺🇸 · Digesh Raut🇺🇸

    We consider a gauged U(1)${}_{B-L}$ (Baryon-minus-Lepton number) extension of the Standard Model (SM), which is anomaly-free in the presence of three Right-Handed Neutrinos (RHNs). Associated with the U(1)${}_{B-L}$ symmetry breaking the RHNs acquire their Majorana masses and then play the crucial role to generate the neutrino mass matrix by the seesaw mechanism. Towards the experimental confirmation of the seesaw mechanism, we investigate a RHN pair production through the U(1)${}_{B-L}$ gauge boson ($Z^{\prime }$) at the 250 GeV International Linear Collider (ILC). The $Z^{\prime }$ gauge boson has been searched at the Large Hadron Collider (LHC) Run-2 and its production cross section is already severely constrained. The constraint will become more stringent by the future experiments with the High-Luminosity upgrade of the LHC (HL-LHC). We find a possibility that even after a null $Z^{\prime }$ boson search result at the HL-LHC, the 250 GeV ILC can search for the RHN pair production through the final state with same-sign dileptons plus jets, which is a `smoking-gun' signature from the Majorana nature of RHNs. In addition, some of RHNs are long-lived and leave a clean signature with a displaced vertex. Therefore, the 250 GeV ILC can operate as not only a Higgs Factory but also a RHN discovery machine to explore the origin of the Majorana neutrino mass generation, namely the seesaw mechanism.

    hep-phhep-exPLB(2019)·47 citations
26. 26*

    Enhanced Di-Higgs Production in the Two Higgs Doublet Model

    K.S. Babu🇺🇸 · Sudip Jana🇺🇸

    We show that the rate for di-Higgs production at the LHC can be enhanced by a factor as large as 25 compared to the Standard Model value in the two Higgs doublet model while being consistent with the known properties of the observed Higgs boson $h$. There are correlated modifications in $t\overline{t}h$ and resonant $Zh$ production rates, which can serve as tests of this model. Our framework treats both Higgs doublets on equal footing, each with comparable Yukawa couplings to fermions. The Cheng-Sher ansatz for multi-Higgs doublet model is shown to be strongly disfavored by current experiments. We propose a new ansatz for the Yukawa couplings of the Higgs doublets ${\Phi }_a$ is proposed, where $Y_{ij}^{(a)}=C_{ij}^{(a)}\cdot \min \{m_i,m_j\}/v$, with $C_{ij}^{(a)}$ being order one coefficients, $m_i$ the mass of fermion $i$ and $v$ the electroweak vacuum expectation value. Such a pattern of couplings can explain the observed features of fermion masses and mixings and satisfies all flavor violation constraints arising from the exchange of neutral Higgs bosons. The rate for $\mu \to e\gamma$ decay and new contributions to CP violation in $B_s-{\overline{B}}_s$ mixing are predicted to be close to the experimental limits.

    hep-phhep-exJHEP(2019)·50 citations
27. 27*

    Gauge-Independent Approach to Resonant Dark Matter Annihilation

    Mateusz Duch🇵🇱 · Bohdan Grzadkowski🇵🇱 · Apostolos Pilaftsis🇬🇧

    In spontaneously broken gauge theories, transition amplitudes describing dark-matter (DM) annihilation processes through a resonance may become highly inaccurate close to a production threshold, if a Breit-Wigner (BW) ansatz with a constant width is used. To partially overcome this problem, the BW propagator needs to be modified by including a momentum dependent decay width. However, such an approach to resonant transition amplitudes generically suffers from gauge artefacts that may also give rise to a bad or ambiguous high-energy behaviour for such amplitudes. We address the two problems of gauge dependence and high-energy unitarity within a gauge-independent framework of resummation implemented by the so-called Pinch Technique. We study DM annihilation via scalar resonances in a gauged U(1)${}_X$ complex-scalar extension of the Standard Model that features a massive stable gauge field which can play the role of the DM. We find that the predictions for the DM abundance may vary significantly from previous studies based on the naive BW ansatz and propose an alternative simple approximation which leads to the correct DM phenomenology. In particular, our results do not depend on the gauge-fixing parameter and are consistent with considerations from high-energy unitarity.

    hep-phJHEP(2019)·6 citations
28. 28*

    Near-the-origin divergence of Klein-Gordon wave functions for hydrogen-like atoms and operator product expansion

    Yingsheng Huang🇨🇳 · Yu Jia🇨🇳 · Rui Yu🇨🇳

    There have been some long-standing puzzles related to the Coulomb solutions of the Klein-Gordon and Dirac equations, namely how to understand the physics underlying the weakly divergent near-the-origin behavior of the $S$-wave wave functions for the hydrogen-like atoms. Taking the Klein-Gordon wave function as a simpler example, in this work we demonstrate that, with the aid of the renormalization group equation, this universal short-distance behavior can be successfully taken into account by the operator product expansion (OPE) formulated in the nonrelativistic effective field theory (EFT), which is tailored for Coulombic atoms. The key is to include the relativistic kinetic correction in the EFT. Somewhat counterintuitively, these universal near-the-origin logarithmic divergences can not be addressed by the OPE set up in the relativistic scalar QED. We conclude that the Klein-Gordon wave function at a length scale shorter than the electron Compton wavelength may cease to make physical significance.

    hep-ph2 citations
29. 29*

    Low-scale Leptogenesis with Minimal Lepton Flavour Violation

    Matthew J. Dolan🇦🇺 · Tomasz P. Dutka🇦🇺 · Raymond R. Volkas🇦🇺

    We analyse the feasibility of low-scale leptogenesis where the inverse seesaw (ISS) and linear seesaw (LSS) terms are not simultaneously present. In order to generate the necessary mass splittings, we adopt a Minimal Lepton Flavour Violation (MLFV) hypothesis where a sterile neutrino mass degeneracy is broken by flavour effects. We find that resonant leptogenesis is feasible in both scenarios. However, because of a flavour alignment issue, MLFV-ISS leptogenesis succeeds only with a highly tuned choice of Majorana masses. For MLFV-LSS, on the other hand, a large portion of parameter space is able to generate sufficient asymmetry. In both scenarios we find that the lightest neutrino mass must be of order $10^{-2}\text{ eV}$ or below for successful leptogenesis. We briefly explore implications for low-energy flavour violation experiments, in particular $\mu \to e\gamma$. We find that the future MEG-II experiment, while sensitive to MLFV in our setup, will not be sensitive to the specific regions required for resonant leptogenesis.

    hep-phPRD(2019)·9 citations
30. 30*

    Tests of Pauli Exclusion Principle Violations from Non-commutative quantum gravity

    Andrea Addazi🇨🇳 · Rita Bernabei🇮🇹

    We review the main recent progresses in non-commutative space-time phenomenology in underground experiments. A popular model of non-commutative space-time is $\theta$-Poincaré model, based on the Groenewold-Moyal plane algebra. This model predicts a violation of the Spin-statistic theorem, in turn implying an energy and angular dependent violation of the Pauli Exclusion principle. Pauli Exclusion Principle Violating transitions in nuclear and atomic systems can be tested with very high accuracy in underground laboratory experiments such as DAMA/LIBRA and VIP(2). In this paper we derive that the $\theta$-Poincaré model can be already ruled-out until the Planck scale, from nuclear transitions tests by DAMA/LIBRA experiment.

    hep-phgr-qchep-thInt.J.Mod.Phys.A(2020)·14 citations
31. 31*

    Lattice QCD and nuclear physics for searches of physics beyond the Standard Model

    Emanuele Mereghetti🇺🇸

    Low-energy tests of fundamental symmetries are extremely sensitive probes of physics beyond the Standard Model, reaching scales that are comparable, if not higher, than directly accessible at the energy frontier. The interpretation of low-energy precision experiments and their connection with models of physics beyond the Standard Model relies on controlling the theoretical uncertainties induced by the nonperturbative nature of QCD at low energy and of the nuclear interactions. In these proceedings, I will discuss how the interplay of Lattice QCD and nuclear Effective Field Theories can lead to improved predictions for low-energy experiments, with controlled uncertainties. I will describe the framework of chiral Effective Field Theory, and then discuss a few examples, including non-standard $\beta$ decays, neutrinoless double beta decay and searches for electric dipole moments, to highlight the progress achieved in recent years, and the role that Lattice QCD will play in addressing the remaining open problems.

    ↳ hep-lathep-phnucl-thPoS(2019)·2 citations
32. 32*

    Extended supersymmetry with central charges in higher dimensional Dirac action

    Yukihiro Fujimoto🇯🇵 · Kouhei Hasegawa🇯🇵 · Kenji Nishiwaki🇰🇷 · Makoto Sakamoto🇯🇵 · Kentaro Tatsumi🇯🇵 · Inori Ueba🇯🇵

    A new realization of extended quantum-mechanical supersymmetry (QM SUSY) with central extension is investigated. We first show that two different sets of $d+2$ ($d+1$) supercharges for $d=$ even (odd), each of which satisfies an $\mathcal{N}=d+2$ ($d+1$) extended QM SUSY algebra without central extension, are hidden in the four-dimensional (4D) mass spectrum of the $(4+d)$-dimensional Dirac action. We then find that the whole set of the supercharges forms an $\mathcal{N}=2d+4$ ($2d+2$) extended QM SUSY algebra with central charges for $d=$ even (odd). The representation of the supersymmetry algebra is shown to be $1/2$-Bogomol'nyi--Prasad--Sommerfield states that correspond to a short representation for the supersymmetry algebra with central extension. We explicitly examine the 4D mass spectrum of the models with the hyperrectangle and the torus extra dimensions, and discuss their supersymmetric structures.

    ↳ hep-thhep-phquant-phPRD(2019)·3 citations
33. 33*

    The third family of neutrinos

    Alain Blondel🇨🇭

    This paper retraces the 24 years starting with the appearance of the symbol "${\nu }_{\tau }$" in 1977, until the observation of tau neutrino interactions with matter in 2000. The fact that the neutral particle present in tau decays was a neutrino was demonstrated by 1979; its existence as the third neutrino ${\nu }_{\tau }$, iso-spin partner of the tau lepton, was definitely established in 1981-1986; it was demonstrated that the number of light active neutrinos is closed with the known ones (${\nu }_e,{\nu }_{\mu },{\nu }_{\tau }$) in 1989; before 2000 the ${\nu }_{\tau }$ properties had been precisely determined in $e^{+}{e}^{-}$ and $p\bar{p}$ collider experiments.

    ↳ physics.hist-phhep-exhep-ph5 citations
34. 34*

    Effective Potential for Revolving D-branes

    Satoshi Iso🇯🇵 · Hikaru Ohta🇯🇵 · Takao Suyama🇯🇵

    We quantize an open string stretched between D0-branes revolving around each other. The worldsheet theory is analyzed in a rotating coordinate system in which the worldsheet fields obey simple boundary conditions, but instead the worldsheet Lagrangian becomes nonlinear. We quantize the system perturbatively with respect to the velocity of the D-branes and determine the one-loop partition function of the open string, from which we extract the short-distance behavior of the effective potential for the revolving D0-branes. It is compared with the calculation of the partition function of open strings between D0-branes moving at a constant relative velocity.

    ↳ hep-thhep-phJHEP(2019)·4 citations
35. 35*

    Neutrino, parity violaton, V-A: a historical survey

    Ludmil Hadjiivanov🇧🇬

    A concise story of the rise of the four fermion theory of the universal weak interaction and its experimental confirmation, with a special emphasis on the problems related to parity violation.

    ↳ physics.hist-phhep-ph3 citations
36. 36*

    RDM-stars as sources of fast radio bursts

    Igor Nikitin🇩🇪

    In this work we consider a recently formulated model of a black hole coupled with radially directed flows of dark matter (RDM-star). In this model, a cutoff by quantum gravity (QG) creates a core of Planck density, filled with a gas of Planck mass particles, inside the star. Further, in this model, a fast radio burst (FRB) can be generated via the following mechanism. An object of an asteroid mass falls onto an RDM-star. Due to large gravitational forces available in the interior, the RDM-star works as a powerful accelerator, boosting the nucleons composing the object to extremely high energies. Upon collision with the core, the nucleons enter in deeply inelastic reactions with the Planck particles composing the core. This process is followed by stimulated emission of highly energetic photons. On the way outside, these photons are subjected to a strong redshift factor, downscaling their frequencies to the radio diapason, as a result producing an FRB. A straightforward computation gives a characteristic upper FRB frequency of 0.6GHz. With attenuation factors, it is stretched to a range 0.35-8GHz, fitting well with the observable FRB frequencies. We also discuss the reconstruction of other FRB parameters in frames of the model.

    ↳ gr-qcastro-ph.HEhep-phin: 2021 J. Phys.: Conf. Ser. 1730 012073·5 citations
37. 37*

    Lensing of fast radio bursts: future constraints on primordial black hole density with an extended mass function and a new probe of exotic compact fermion and boson stars

    Ranjan Laha🇩🇪

    The discovery of gravitational waves from binary black hole mergers has renewed interest in primordial black holes forming a part of the dark matter density of our Universe. Various tests have been proposed to test this hypothesis. One of the cleanest tests is the lensing of fast radio bursts. In this situation, the presence of a compact object near the line of sight produces two images of the radio burst. If the images are sufficiently separated in time, this technique can constrain the presence of primordial black holes. One can also try to detect the lensed image of the mini-bursts within the main burst. We show that this technique can produce the leading constraints over a wide range in lens masses $\gtrsim$ 2 $M_{\odot }$ if the primordial black holes follow a single mass distribution. Even if the primordial black holes have an extended mass distribution, the constraints that can be derived from lensing of fast radio bursts will be the most constraining over wide ranges of the parameter space. We show that this technique can probe exotic compact boson stars and fermion stars made up of beyond the Standard Model particles. This search strategy is competitive and can provide the leading constraints on parts of the particle physics parameter space when compared with gravitational wave observations.

    ↳ astro-ph.COhep-exhep-phPRD(2020)·56 citations
38. 38*

    Touschek with AdA in Orsay and the first direct observation of electron-positron collisions

    Giulia Pancheri🇮🇹 · Luisa Bonolis🇩🇪

    We describe how the first direct observation of electron-positron collisions took place in 1963-1964 at the Laboratoire de l'Accélérateur Linéaire d'Orsay, in France, with the storage ring AdA, which had been proposed and constructed in the Italian National Laboratories of Frascati in 1960, under the guidance of Bruno Touschek. The obstacles and successes of the two and a half years during which the feasibility of electron-positron colliders was proved will be illustrated using archival and forgotten documents, in addition to transcripts from interviews with Carlo Bernardini, Peppino Di Giugno, Mario Fascetti, Francois Lacoste, and Jacques Haïssinski.

    ↳ physics.hist-phhep-phphysics.acc-ph6 citations
39. 39*

    Hybrid equation of state with pasta phases and third family of compact stars

    K. Maslov🇷🇺 · N. Yasutake🇯🇵 · A. Ayriyan🇷🇺 · D. Blaschke🇵🇱 · H. Grigorian🇷🇺 · T. Maruyama🇯🇵 · T. Tatsumi🇯🇵 · D. N. Voskresensky🇷🇺

    The effect of pasta phases on the quark-hadron phase transition is investigated for a set of relativistic mean-field equations of state for both hadron and quark matter. The results of the full numerical solution with pasta phases are compared with those of an interpolating construction used in previous works, for which we demonstrate an adequate description of the numerical results. A one-to-one mapping of the free parameter of the construction to the physical surface tension of the quark-hadron interface is obtained for which a fit formula is given. For each pair of quark and hadron matter models the critical value of the surface tension is determined, above which the phase transition becomes close to the Maxwell construction. This result agrees well with earlier theoretical estimates. The study is extended to neutron star matter in beta equilibrium with electrons and muons and is applied to investigate the effect of pasta phases on the structure of hybrid compact stars and the robustness of a possible third family solution.

    ↳ nucl-thastro-ph.HEhep-phPRC(2019)·78 citations
40. 40*

    The path from finite to infinite volume: Hadronic observables from lattice QCD

    Zohreh Davoudi🇺🇸

    Standard Model determinations of properties of strongly interacting systems of hadrons have become possible with the powerful method of lattice quantum chromodynamics (LQCD), a method with growing applicability and reliability. While growth in computational power and innovations in algorithmic and computational approaches have been essential in advancing the state of the field, conceptual and formal developments have played a crucial role in turning the output of LQCD computations to phenomenologically valuable results. From the invention of finite-volume technology to access physical observables by Martin Lüscher over three decades ago to date, this field has grown in scope and complexity, enabling studies of scattering amplitudes and reaction rates, as well as spectroscopy of excited states of quantum chromodynamics (QCD) and resonances. Further, LQCD studies are augmented with the inclusion of quantum electrodynamics (QED), and subtleties related to the finite volume of systems in presence of QED have been understood and largely controlled. In this talk, I focus on selected developments to give a taste of the status of the field concerning the mapping between the finite and infinite-volume physics and its state-of-the-art applications.

    ↳ hep-lathep-phnucl-thPoS(2018)·7 citations
41. 41*

    Enhancement of axion decay constants in type IIA theory?

    Gaurav Goswami🇮🇳

    We investigate the possibility of enhancement of effective axion decay constant in well controlled constructions in string theory. To this end, we study the dynamics of axions arising in the compactifications of type IIA string theory on Calabi-Yau orientifolds with background fluxes (with non-perturbative effects included to ensure stabilization of all moduli). In this setup, we attempt to obtain large effective axion decay constant in two different ways: by searching for a direction in field space in which the potential is sufficiently flat and by arriving at a very explicit stringy embedding of the Kim-Nilles-Peloso (KNP) alignment mechanism. We do not find super-Planckian effective decay constants by either of the approaches. Furthermore, we find that the alignment angle of KNP mechanism can not be made arbitrarily small by adjusting the fluxes.

    ↳ hep-thastro-ph.COhep-phPRD(2019)·5 citations
42. 42*

    Adjoint QCD${}_4$, Deconfined Critical Phenomena, Symmetry-Enriched Topological Quantum Field Theory, and Higher Symmetry-Extension

    Zheyan Wan🇨🇳 · Juven Wang🇺🇸

    Recent work explores the candidate phases of the 4d adjoint quantum chromodynamics (QCD${}_4$) with an SU(2) gauge group and two massless adjoint Weyl fermions. Both Cordova-Dumitrescu and Bi-Senthil propose possible low energy 4d topological quantum field theories (TQFTs) to saturate the higher 't Hooft anomalies of adjoint QCD${}_4$ under a renormalization-group (RG) flow from high energy. In this work, we generalize the symmetry-extension method [arXiv:1705.06728] to higher symmetries, and formulate higher group cohomology and cobordism theory approach to construct higher-symmetric TQFTs. We prove that the symmetry-extension method saturates certain anomalies, but also prove that neither $A{\mathcal{P}}_2(B_2)$ nor ${\mathcal{P}}_2(B_2)$ can be fully trivialized, with the background 1-form field $A$, Pontryagin square ${\mathcal{P}}_2$ and 2-form field $B_2$. Surprisingly, this indicates an obstruction to constructing a fully 1-form center and 0-form chiral symmetry (full discrete axial symmetry) preserving 4d TQFT with confinement, a no-go scenario via symmetry-extension for specific higher anomalies. We comment on the implications and constraints on deconfined quantum critical points (dQCP), quantum spin liquids (QSL) or quantum fermionic liquids in condensed matter, and ultraviolet-infrared (UV-IR) duality in 3+1 spacetime dimensions.

    ↳ hep-thcond-mat.str-elhep-lathep-ph+1PRD(2019)·94 citations
43. 43*

    Higher Anomalies, Higher Symmetries, and Cobordisms I: Classification of Higher-Symmetry-Protected Topological States and Their Boundary Fermionic/Bosonic Anomalies via a Generalized Cobordism Theory

    Zheyan Wan🇨🇳 · Juven Wang🇺🇸

    By developing a generalized cobordism theory, we explore the higher global symmetries and higher anomalies of quantum field theories and interacting fermionic/bosonic systems in condensed matter. Our essential math input is a generalization of Thom-Madsen-Tillmann spectra, Adams spectral sequence, and Freed-Hopkins's theorem, to incorporate higher-groups and higher classifying spaces. We provide many examples of bordism groups with a generic $H$-structure manifold with a higher-group $\mathbb{G}$, and their bordism invariants --- e.g. perturbative anomalies of chiral fermions [originated from Adler-Bell-Jackiw] or bosons with U(1) symmetry in any even spacetime dimensions; non-perturbative global anomalies such as Witten anomaly and the new SU(2) anomaly in 4d and 5d. Suitable $H$ such as SO/Spin/O/Pin${}^{\pm }$ enables the study of quantum vacua of general bosonic or fermionic systems with time-reversal or reflection symmetry on (un)orientable spacetime. Higher 't Hooft anomalies of $d$d live on the boundary of $(d+1)$d higher-Symmetry-Protected Topological states (SPTs) or symmetric invertible topological orders (i.e., invertible topological quantum field theories at low energy); thus our cobordism theory also classifies and characterizes higher-SPTs. Examples of higher-SPT's anomalous boundary theories include strongly coupled non-Abelian Yang-Mills gauge theories and sigma models, complementary to physics obtained in [arXiv:1810.00844, 1812.11955, 1812.11968, 1904.00994].

    ↳ hep-thcond-mat.str-elhep-phmath.AT+1Ann.Math.Sci.Appl.(2019)·144 citations
44. 44*

    New Higher Anomalies, SU(N) Yang-Mills Gauge Theory and ${\mathbb{CP}}^{\mathrm{N}-1}$ Sigma Model

    Zheyan Wan🇨🇳 · Juven Wang🇺🇸 · Yunqin Zheng🇺🇸

    We hypothesize a new and more complete set of anomalies of certain quantum field theories (QFTs) and then give an eclectic verification. First, we propose a set of 't Hooft higher anomalies of 4d time-reversal symmetric pure SU(N)-Yang-Mills (YM) gauge theory with a second-Chern-class topological term at $\theta =\pi$, via 5d cobordism invariants (higher symmetry-protected topological states), with N = $2,3,4$ and others. Second, we propose a set of 't Hooft anomalies of 2d ${\mathbb{CP}}^{\mathrm{N}-1}$-sigma models with a first-Chern-class topological term at $\theta =\pi$, by enlisting all possible 3d cobordism invariants and selecting the matched terms. Based on algebraic/geometric topology, QFT analysis, manifold generator correspondence, condensed matter inputs such as stacking PSU(N)-generalized Haldane quantum spin chains, and additional physics criteria, we derive a correspondence between 5d and 3d new invariants. Thus we broadly prove a potentially complete anomaly-matching between 4d SU(N) YM and 2d ${\mathbb{CP}}^{\mathrm{N}-1}$ models at N = 2, and suggest new (but maybe incomplete) anomalies at N = 4. We formulate a higher-symmetry analog of "Lieb-Schultz-Mattis theorem" to constrain the low-energy dynamics.

    ↳ hep-thcond-mat.str-elhep-lathep-ph+1Annals Phys.(2020)·62 citations
45. 45*

    Hydrodynamics of Fermi arcs: Bulk flow and surface collective modes

    E. V. Gorbar🇺🇦 · V. A. Miransky🇨🇦 · I. A. Shovkovy🇺🇸 · P. O. Sukhachov🇨🇦

    The hydrodynamic description of the Fermi arc surface states is proposed. In view of the strong suppression of scattering on impurities, the hydrodynamic regime for Fermi arc states should be, in principle, plausible. By using the kinetic theory, the Fermi arc hydrodynamics is derived and the corresponding effects on the bulk flow and surface collective modes are studied. For the bulk flow, the key effect of the proposed Fermi arc hydrodynamics is the modification of the corresponding boundary conditions. In a slab geometry, it is shown that, depending on the transfer rates between the surface and bulk, the hydrodynamic flow of the electron fluid inside the slab could be significantly altered and even enhanced near the surfaces. As to the spectrum of the surface collective modes, in agreement with earlier studies, it is found that the Fermi arcs allow for an additional gapless spectrum branch and a strong anisotropy of the surface plasmon dispersion relations in momentum space. The gapped modes are characterized by closed elliptic contours of constant frequency in momentum space.

    ↳ cond-mat.str-elhep-phnucl-thPRB(2019)·12 citations
46. 46*

    Lattice-QCD Determination of the Hyperon Axial Couplings in the Continuum Limit

    Aditya Savanur🇺🇸 · Huey-Wen Lin🇺🇸

    We present the first continuum extrapolation of the hyperon octet axial couplings ($g_{\Sigma \Sigma }$ and $g_{\Xi \Xi }$) from $N_f=2+1+1$ lattice QCD. These couplings are important parameters in the low-energy effective field theory description of the octet baryons and fundamental to the nonleptonic decays of hyperons and to hyperon-hyperon and hyperon-nucleon scattering with application to neutron stars. We use clover lattice fermion action for the valence quarks with sea quarks coming from configurations of $N_f=2+1+1$ highly improved staggered quarks (HISQ) generated by MILC Collaboration. Our work includes the first calculation of $g_{\Sigma \Sigma }$ and $g_{\Xi \Xi }$ directly at the physical pion mass on the lattice, and a full account of systematic uncertainty, including excited-state contamination, finite-volume effects and continuum extrapolation, all addressed for the first time. We find the continuum-limit hyperon coupling constants to be $g_{\Sigma \Sigma }=0.4455(55{)}_{\text{stat}}(65{)}_{\text{sys}}$ and $g_{\Xi \Xi }=-0.2703(47{)}_{\text{stat}}(13{)}_{\text{sys}}$, which correspond to low-energy constants of $D=0.708(10{)}_{\text{stat}}(6{)}_{\text{sys}}$ and $F=0.438(7{)}_{\text{stat}}(6{)}_{\text{sys}}$. The corresponding SU(3) symmetry breaking is 9\% which is about a factor of 2 smaller than the earlier lattice estimate.

    ↳ hep-lathep-phPRD(2020)·11 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.