Thu·May 17, 2018Thursday·May 17, 2018

1. 01*

   Dark Glueballs and their Ultralight Axions

   James Halverson🇺🇸 · Brent D. Nelson🇺🇸 · Fabian Ruehle🇬🇧 · Gustavo Salinas🇺🇸

   Dark gauge sectors and axions are well-motivated in string theory. We demonstrate that if a confining gauge sector gives rise to dark glueballs that are a fraction of the dark matter, and the associated axion has a decay constant near the string scale, then this axion is ultralight and naturally realizes the fuzzy dark matter scenario with a modest tuning of a temperature ratio. Astrophysical observations constrain the size of the glueball component relative to the axionic component, while electric dipole moments constrain mixing with the QCD axion.

   hep-phhep-thPRD(2018)·29 citations
2. 02*

   Heavy Quark Jet Fragmentation

   Lin Dai · Chul Kim · Adam K. Leibovich

   In this paper we study the fragmentation of a parton into a jet containing a heavy quark. When heavy quarks are involved in a jet, the quark mass can lead to a numerically significant correction to the jet cross section and its substructure. With this motivation, we calculated the heavy quark mass effects to next-to-leading order in ${\alpha }_s$ on the fragmentation functions to a jet (FFJs) and the jet fragmentation functions (JFFs), where the former describes fragmentation of parton into a jet and the latter describes fragmenting processes inside a jet. The finite size of the heavy quark mass does not change the ultraviolet behaviors, but it can give significant corrections to the finite contributions. When we take the zero mass limit, we find that the FFJs and the JFFs reproduce established results for massless partons. If we define the heavy quark jet as one that include at least one heavy (anti-)quark, the tagged heavy quark jet production is sensitive to the heavy quark mass and produces large logarithms of the mass. Taking advantage of the FFJs and JFFs, we formulate a factorization theorem for heavy quark jet production in order to resum these large logarithms systematically. As an application, we study inclusive $b$-jet production and show phenomenological implications due to keeping a non-zero quark mass.

   hep-phJHEP(2018)·27 citations
3. 03*

   Global analyses of supersymmetry with GAMBIT

   Pat Scott (for the GAMBIT Collaboration)🇬🇧

   I provide a brief summary of the status of supersymmetric models with parameters defined at either the unification or weak scale, based on global fits using the GAMBIT framework.

   hep-ph0 citations
4. 04*

   $B-L$ violating nucleon decays as a probe of leptoquarks and implications for baryogenesis

   Chandan Hati🇫🇷 · Utpal Sarkar🇮🇳

   We study the effective $B-L$ violating couplings for scalar and vector leptoquarks which can naturally induce dimension seven $B-L$ violating operators leading to very interesting nucleon decay modes such as $n\to e^{-}{\pi }^{+},e^{-}{K}^{+},{\mu }^{-}{\pi }^{+},{\mu }^{-}{K}^{+}$ and $p\to \nu {\pi }^{+}$. This opens a new window to probe the nature and couplings of the scalar and vector leptoquarks in an ultraviolet model independent way which can provide an orthogonal probe for scalar and vector leptoquark solutions to the recent anomalous $B$-decay data. Furthermore, we also discuss how these $B-L$ violating interactions can also pave a new way to understand the origin of matter-antimatter asymmetry of the Universe.

   hep-phhep-exNPB(2020)·15 citations
5. 05*

   A possible partner state of the $Y(2175)$

   Hua-Xing Chen🇨🇳 · Cheng-Ping Shen🇨🇳 · Shi-Lin Zhu🇨🇳

   We study the $Y(2175)$ using the method of QCD sum rules. There are two independent $ss\bar{s}\bar{s}$ interpolating currents with $J^{PC}=1^{--}$, and we calculate both their diagonal and off-diagonal correlation functions. We obtain two new currents which do not strongly correlate to each other, so they may couple to two different physical states: one of them couples to the $Y(2175)$, while the other may couple to another state whose mass is about $71_{-48}^{+172}$ MeV larger. Evidences of the latter state can be found in the BaBar, BESII, Belle, and BESIII experiments.

   hep-phhep-latPRD(2018)·48 citations
6. 06*

   Present and projected sensitivities of Dark Matter direct detection experiments to effective WIMP-nucleus couplings

   Sunghyun Kang🇰🇷 · Stefano Scopel🇰🇷 · Gaurav Tomar🇰🇷 · Jong-Hyun Yoon (Sogang U.)🇰🇷

   Assuming for Weakly Interacting Massive Particles (WIMPs) a Maxwellian velocity distribution in the Galaxy we explore in a systematic way the relative sensitivity of an extensive set of existing and projected Dark Matter (DM) direct detection experiments to each of the 14 couplings that parameterize the most general non-relativistic (NR) effective Hamiltonian allowed by Galilean invariance for a contact interaction driving the elastic scattering off nuclei of WIMPs of spin 1/2. We perform our analysis in terms of two free parameters: the WIMP mass $m_{\chi }$ and the ratio between the WIMP-neutron and the WIMP-proton couplings $c^n/c^p$. We include the modified signal spectral shape due to non-standard interactions when it is needed in the determination of the bound, such as in the case of background subtraction or of the application of the optimal-interval method. For each coupling, in the $m_{\chi }$-$c^n/c^p$ plane we provide contour plots of the most stringent 90 % C.L. bound on the WIMP-nucleon cross section and show the experiment providing it. We also introduce NRDD_constraints, a simple interpolating code written in Python that allows to obtain the numerical value of the bound as a function of the WIMP mass $m_{\chi }$ and of the coupling ratio $c^n/c^p$ for each NR coupling. We find that 9 experiments out of the 14 present Dark Matter searches considered in our analysis provide the most stringent bound on some of the effective couplings for a given choice of $(m_{\chi },c^n/c^p)$: this is evidence of the complementarity of different target nuclei and/or different combinations of count-rates and energy thresholds when the search of DM is extended to a wide range of possible interactions.

   hep-phastro-ph.COAstropart.Phys.(2019)·42 citations
7. 07*

   The least constrained supersymmetry with R-parity violation

   Jinmian Li🇰🇷 · Tianjun Li🇨🇳 · Wenxing Zhang🇨🇳

   The strong constraints on the R-parity conserving supersymmetry (SUSY) from the LHC searches motivate us to consider the new models in which the low-scale SUSY is still allowed. We propose a kind of R-parity violating SUSY scenarios with a non-zero $U_2^c{D}_2^c{D}_3^c$ operator. Three relevant LHC searches are recasted to test the status of this scenario in terms of four simplified models, with either light stop-Bino, stop-Higgsino, sbottom-Bino or sbottom-Higgsino. Some difficult scenarios for the LHC SUSY searches in these simplified models are identified. By extrapolate the current LHC searches to the future 14 TeV LHC with integrated luminosity of 300 fb${}^{-1}$, most of the difficult scenarios can be probed, except the sbottom-Bino simplified one. An improved search, which utilises the multiple b-jets as well as its kinematic features, is expected to probe the signature of this case.

   hep-phPRD(2019)·5 citations
8. 08*

   Light dark sector at colliders and fixed target experiments

   Luc Darmé🇵🇱 · Soumya Rao🇵🇱 · Leszek Roszkowski🇵🇱

   Minimal scenarios with light (sub-GeV) thermal dark matter are usually accompanied by a correspondingly light "dark sector". Taking as an example a simple fermionic dark matter model, we will show that the presence of the dark sector plays a key role in constraining such scenarios at accelerators experiments. The effect of including a dark Higgs boson in the light spectrum is in particular investigated.

   hep-ph2 citations
9. 09*

   Including higher-order mixed QCD-QED effects in hadronic calculations

   German F. R. Sborlini🇮🇹

   We review some recent results about the computation of mixed QCD-QED corrections beyond the leading order in perturbation theory. We start by considering the effects induced in the Altarelli-Parisi equations and the partonic distributions. In particular, we describe the computation of one-loop mixed QCD-QED and two-loop QED terms in the splitting kernels, which are relevant to account for the presence of photon distributions. In the last part, we briefly talk about the implementation of these corrections in the context of the $q_T$-subtraction/resummation formalism.

   hep-ph4 citations
10. 10*

    Influence of vector interactions on the favored shape of inhomogeneous chiral condensates

    Stefano Carignano🇪🇸 · Marco Schramm🇩🇪 · Michael Buballa🇩🇪

    We update a previous study of the effects of vector interactions in the Nambu--Jona-Lasinio model on the formation of inhomogeneous chiral symmetry breaking condensates. In particular, by properly considering a spatially modulated vector mean-field associated with the quark number density of the system we show that, as the value of the vector coupling increases, a chiral density wave modulation can become thermodynamically favored over a real sinusoidal modulation. This behavior is found both via a Ginzburg-Landau analysis close to the Lifshitz point, as well as with a full numerical diagonalization of the mean-field Dirac Hamiltonian at vanishing temperature.

    hep-phnucl-thPRD(2018)·19 citations
11. 11*

    TeV SUSY dark matter confronted with the current direct and indirect detection data

    Murat Abdughani🇨🇳 · Jie Ren🇨🇳 · Jun Zhao🇨🇳

    In the minimal supersymmetric standard model (MSSM) the lightest superparticle (LSP) can be a TeV neutralino (mainly dominated by higgsino or wino) which serves as a dark matter candidate with correct thermal relic density. In this work we confront the 1-2 TeV neutralino dark matter with the latest direct and indirect detections from PandaX and AMS-02/DAMPE. Considering various scenarios with decoupled sfermions, with \textit{A}-mediated annihilation, with squark or stop coannihilation, we find that the parameter space is stringently constrained by the direct detection limits. In the allowed parameter space, the TeV neutralino dark matter annihilation contribution to the anti-proton flux is found to agree with the AMS-02 data while its contribution to eletron/positron flux is too small to cause any visible excess. The current survived parameter space can be mostly covered by the future direct detection experiment LZ7.2T.

    hep-phastro-ph.HEhep-exEPJC(2019)·5 citations
12. 12*

    Exclusive photoproduction of vector mesons in proton-lead ultraperipheral collisions at the LHC

    Ya-Ping Xie🇨🇳 · Xurong Chen🇨🇳

    Rapidity distributions of vector mesons are computed in dipole model proton-lead ultraperipheral collisions(UPCs) at the CERN Larger Hadron Collider(LHC). The dipole model framework is implemented in the calculations of cross sections in the photon-hadron interaction. The bCGC model and Boosted Gaussian wave functions are employed in the scattering amplitude. We obtain predictions of rapidity distributions of $J/\psi$ meson proton-lead ultraperipheral collisions. The predictions give a good descriptions to the experimental data of ALICE. The rapidity distributions of $\varphi$, $\omega$ and $\psi (2s)$ mesons in proton-lead ultraperipheral collisions are also presented in this paper.

    hep-phNPA(2018)·12 citations
13. 13*

    Electric Dipole Moments and Neutrino Mass Models

    Selim Touati🇫🇷

    While Jarlskog-like flavor invariants are adequate for estimating CP-violation from closed fermion loops, non-invariant structures arise from rainbow-like processes. For the CKM contributions to the quark electric dipole moments (EDMs), or the PMNS contributions to lepton EDMs, the dominant diagrams have a rainbow topology whose flavor structure does not collapse to flavor invariants. Numerically, they are found typically much larger, and not necessarily correlated with, Jarlskog-like invariants. The flavor structures in the quark and lepton sectors are systematically studied, assuming different mechanisms for generating neutrino masses. In addition, the combined study of both Jarlskog-like and rainbow-like flavor structures shed new lights on the possible correlations between quark and lepton EDMs.

    hep-ph1 citation
14. 14*

    Diffusion coefficients and constraints on hadronic inhomogeneities in the early universe

    Sovan Sau🇮🇳 · Sayantan Bhattacharya🇮🇳 · Soma Sanyal🇮🇳

    Hadronic inhomogeneities are formed after the quark hadron phase transition. The nature of the phase transition dictates the nature of the inhomogeneities formed. Recently some scenarios of inhomogeneities have been discussed where the strange quarks are in excess over the up and down quarks. The hadronization of these quarks will give rise to a large density of hyperons and kaons in addition to the protons and neutrons which are formed after the phase transition. These unstable hyperons decay into pions, muons and their respective neutrinos. Hence the plasma during this period consists of neutrons, protons, electrons, muons and neutrinos. Due to the decay of the hyperons, the muon component of the inhomogeneities will be very high. We study the diffusion of neutrons and protons in the presence of a large number of muons immediately after the quark hadron phase transition. We find that the presence of the muons enhances the diffusion coefficient of the neutrons/protons. As the diffusion coefficient is enhanced, the inhomogeneities will decay faster in the regions where the muon density is higher. Hence smaller muon rich inhomogeneities will be completely wiped out. The decay of the hyperons will also generate muon neutrinos. Since the big bang nucleosynthesis provides constraints on the neutrino degeneracies, we revisit the effect of non zero degeneracies on the primordial elements.

    hep-phastro-ph.COEPJC(2019)·4 citations
15. 15*

    Higher-order one-loop contributions in Lorentz-breaking QED

    A. P. Baeta Scarpelli🇧🇷 · L. C. T. Brito🇧🇷 · J. C. C. Felipe🇧🇷 · J. R. Nascimento🇧🇷 · A. Yu. Petrov🇧🇷

    We calculate higher-order quantum contributions in different Lorentz-violating parameters to the gauge sector of the extended QED. As a result of this one-loop calculation, some terms which do not produce first-order corrections, contribute with nontrivial gauge-invariant second-order quantum inductions.

    hep-phhep-thEPL(2018)·8 citations
16. 16*

    Spectroscopy of the hidden-charm $[qc][\bar{q}\bar{c}]$ and $[sc][\bar{s}\bar{c}]$ tetraquarks

    Muhammad Naeem Anwar🇨🇳 · Jacopo Ferretti🇨🇳 · Elena Santopinto🇮🇹

    We calculate the spectrum of $q\bar{q}c\bar{c}$ and $s\bar{s}c\bar{c}$ tetraquarks, where $q$, $s$ and $c$ stand for light ($u,d$), strange and charm quarks, respectively, in a relativized diquark model, characterized by one-gluon-exchange (OGE) plus confining potential. In the diquark model, a $q\bar{q}c\bar{c}$ ($s\bar{s}c\bar{c}$) tetraquark configuration is made up of a heavy-light diquark, $qc$ ($sc$), and anti-diquark, $\bar{q}\bar{c}$ ($\bar{s}\bar{c}$). According to our results, 13 charmonium-like observed states can be accommodated in the tetraquark picture, both in the hidden-charm ($q\bar{q}c\bar{c}$) and hidden-charm hidden-strange ($s\bar{s}c\bar{c}$) sectors.

    hep-phhep-exnucl-thPRD(2018)·79 citations
17. 17*

    Pair production of the lightest chargino at $\gamma \gamma$-collider

    Nasuf Sonmez🇹🇷

    Chargino pair production via photon-photon collision is investigated in the Minimal Supersymmetric Standard Model at a future linear collider. The process is computed using all the possible diagrams at the next-to-leading order, including box, triangle, and self-energy diagrams. The numerical analysis is carried out for the production rates of the lightest chargino pair in RNS, NS, mSUGRA, BB, and NUGM scenarios. These distinct benchmark models were introduced in the light of the LHC results presented at $\sqrt{s}=7-8\text{ TeV}$. Among these scenarios, the RNS has the highest production rate for the $\gamma \gamma \to {\tilde{\chi }}_1^{+}{\tilde{\chi }}_1^{-}$. The partonic cross section reaches up to $3.94\text{ pb}$ at $\sqrt{\hat{s}}=310\text{ GeV}$. The total convoluted cross section with the photon luminosity in a $e^{+}{e}^{-}$ machine is calculated as a function of the center-of-mass energy up to $1\text{ TeV}$. The convoluted cross section is $\sim 1.05\text{ pb}$ at $\sqrt{s}=350\text{ GeV}$ depending on the polarization of the initial electron and laser polarization. The RNS along with the BB scenarios are accessible at $\sqrt{s}=500\text{ GeV}$ with a $\gamma \gamma$ collision mode on $e^{+}{e}^{-}$-collider.

    hep-phNPB(2019)·3 citations
18. 18*

    Prospects for disentangling long- and short-distance effects in the decays $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$

    Marcin Chrzaszcz🇨🇭 · Andrea Mauri🇨🇭 · Nicola Serra🇨🇭 · Rafael Silva Coutinho🇨🇭 · Danny van Dyk🇩🇪

    Theory uncertainties on non-local hadronic effects limit the New Physics discovery potential of the rare decays $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$. We investigate prospects to disentangle New Physics effects in the short-distance coefficients from these effects. Our approach makes use of an event-by-event amplitude analysis, and relies on the state of the art parametrisation of the non-local contributions. We find that non-standard effects in the short-distance coefficients can be successfully disentangled from non-local hadronic effects. The impact of the truncation on the parametrisation of non-local contributions to the Wilson coefficients are for the first time systematically examined and prospects for its precise determination are discussed. We find that physical observables are unaffected by these uncertainties. Compared to other methods, our approach provides for a more precise extraction of the angular observables from data.

    hep-phhep-exJHEP(2019)·44 citations
19. 19*

    Z polarization in $\gamma \gamma$,gluon-gluon $\to t\bar{t}Z$ for testing the top quark mass structure and the presence of final interactions

    Fernand M Renard🇫🇷

    We show what type of effects on the rate of $Z_L$ production in the $\gamma \gamma \to t\bar{t}Z$ and $gluongluon\to t\bar{t}Z$ processes could be produced by an effective scale dependent top mass or by final state interactions between massive particles for example generated by the presence of dark matter.

    hep-ph3 citations
20. 20*

    Role of the $Z$ polarization in the $H\to b\bar{b}$ measurement

    Dorival Goncalves🇺🇸 · Junya Nakamura🇩🇪

    It is widely known that the $ZH$ production channel provides a promising probe to the $H\to b\bar{b}$ decay at the LHC, when the Higgs and the $Z$ bosons are highly boosted along the transverse direction. We show how information on the $Z$ boson polarization -- that is disregarded in the current LHC analyses -- can relevantly improve the signal from background discrimination, helping us to observe and achieve a larger precision for the $H\to b\bar{b}$ measurement in the $Z(\ell \ell )H$ channel.

    hep-phhep-exPRD(2018)·35 citations
21. 21*

    Towards establishing Lepton Flavour Universality violation in $\bar{B}\to {\bar{K}}^{\ast }{\ell }^{+}{\ell }^{-}$ decays

    Andrea Mauri🇨🇭 · Nicola Serra🇨🇭 · Rafael Silva Coutinho🇨🇭

    Rare semileptonic $b\to s{\ell }^{+}{\ell }^{-}$ transitions provide some of the most promising frameworks to search for new physics effects. Recent analyses of these decays have indicated an anomalous behaviour in measurements of angular distributions of the decay $B^0\to K^{\ast }{\mu }^{+}{\mu }^{-}$ and lepton-flavour-universality observables. Unambiguously establishing if these deviations have a common nature is of paramount importance in order to understand the observed pattern. We propose a novel approach to independently and complementary probe this hypothesis by performing a simultaneous amplitude analysis of ${\bar{B}}^0\to {\bar{K}}^{\ast 0}{\mu }^{+}{\mu }^{-}$ and ${\bar{B}}^0\to {\bar{K}}^{\ast 0}{e}^{+}{e}^{-}$ decays. This method enables the direct determination of observables that encode potential non-equal couplings of muons and electrons, and are found to be insensitive to nonperturbative QCD effects. If current hints of new physics are confirmed, our approach could allow an early discovery of physics beyond the standard model with LHCb run II data sets.

    hep-phhep-exPRD(2019)·17 citations
22. 22*

    Single production of vector-like quarks with large width at the Large Hadron Collider

    Alexandra Carvalho🇪🇪 · Stefano Moretti🇬🇧 · Dermot O'Brien🇬🇧 · Luca Panizzi🇮🇹 · Hugo Prager🇬🇧

    Vector-Like Quarks (VLQs) are predicted by several theoretical scenarios of new physics and, having colour quantum numbers, can copiously be produced at the Large Hadron Collider (LHC), so long that their mass is in the testable kinematic regime of such a machine. While it would be convenient to assume that such objects are narrow and can be treated in the so-called Narrow Width Approximation (NWA), this is not always possible, owing to the fact that couplings and particle content of such new physics scenarios are not generally constrained, so that a large value of the former and/or a large variety of VLQ decay channels into the latter can contribute to generate a large decay width for such extra quarks. We have addressed here the issue of how best to tackle in LHC analysis the presence of large (and model-dependent) interference effects between different VLQ production and decay channels as well as between these and the corresponding irreducible background. We have confined ourselves to the case of single production of VLQs, which is rapidly becoming a channel of choice in experimental searches owing to the ever increasing limits on their mass, in turn depleting the yield of the historically well-established double production channel. Indeed, this poses a further challenge, as the former is model-dependent while the latter is essentially not. Despite these conditions, we show here that an efficient approach is possible, which retains to a large extent a degree of model independence in phenomenological studies of such VLQ dynamics at the LHC.

    hep-phPRD(2018)·73 citations
23. 23*

    Rates and differential distributions in heavy neutral leptons production and decays

    Jean-Michel Levy🇫🇷

    Production and decay rates, polarization and differential distributions of decay products are calculated for a heavy neutrino produced in charged pseudoscalar meson decay and decaying itself in charged pseudoscalar and lepton or a lepton-antilepton pair of different flavours and a light SM like (anti)neutrino.

    hep-phhep-ex9 citations
24. 24*

    Four-loop splitting functions at small $x$

    Marco Bonvini🇮🇹 · Simone Marzani🇮🇹

    We consider the expansion of small-$x$ resummed DGLAP splitting functions at next-to-leading logarithmic (NLL) accuracy to four-loop order, namely next-to-next-to-next-to-leading order (N${}^3$LO). From this, we extract the exact LL and NLL small-$x$ contributions to the yet unknown N${}^3$LO splitting functions, both in the standard $\overline{MS}$ scheme and in the $Q_0\overline{MS}$ scheme usually considered in small-$x$ literature. We show that the impact of unknown subleading logarithmic contributions (NNLL and beyond) at N${}^3$LO is significant, thus motivating future work towards their computation. Our results will be also needed in future to match NLL resummation to N${}^3$LO evolution. In turn, we propose an improved implementation of the small-$x$ resummation and therefore release a new version of the resummation code (HELL 3.0) which contains these changes.

    hep-phJHEP(2018)·32 citations
25. 25*

    Color Unifed Dynamical Axion

    M.K. Gaillard🇺🇸 · M.B. Gavela🇪🇸 · R. Houtz🇪🇸 · P. Quilez🇪🇸 · R. del Rey🇪🇸

    We consider an enlarged color sector which solves the strong CP problem via new massless fermions. The spontaneous breaking of a unified color group into QCD and another confining group provides a source of naturally large axion mass $m_a$ due to small size instantons. This extra source of axion mass respects automatically the alignment of the vacuum, ensuring a low-energy CP-conserving vacuum. The mechanism does not appeal to a $Z_2$ 'mirror' copy of the SM, nor does it require any fine-tuning of the axion-related couplings at the unification scale. There is no light axion and uncharacteristically the lighter spectrum contains instead sterile fermions. The axion scale $f_a$ can be naturally brought down to a few TeV, with an exotic spectrum of colored pseudoscalars lighter than this scale, observable at colliders exclusively via strong interactions. The $\{m_a,f_a\}$ parameter space which allows a solution of the strong CP problem is thus enlarged well beyond that of invisible axion models.

    hep-phEPJC(2018)·147 citations
26. 26*

    Plasma Effects on Lasing of Uniform Ultralight Axion Condensate

    Srimoyee Sen🇺🇸

    Lasing of ultralight axion condensate into photons can be sensitive to the presence of a background plasma owing to its coupling to electromagnetism. Such a scenario is particularly relevant for superradiant axion condensate around stellar mass black holes since the axion mass can be within a few orders of magnitude of the plasma frequency of the surrounding medium. In this paper I discuss the properties of the plasma around a black hole and analyze its effects on the lasing of a uniform axion condensate of mass of the order of the plasma frequency.

    hep-phastro-ph.HEPRD(2018)·54 citations
27. 27*

    Electric dipole moment of light nuclei - 6Li, 7Li, 9Be, 11B, and 13C -

    Nodoka Yamanaka🇫🇷

    In this proceeding, we present the results of the theoretical evaluations of the electric dipole moment (EDM) of light nuclei, including the preliminary value for the 11B nucleus. From the data, we can infer an approximate counting rule, and predict the EDM of other light nuclei.

    ↳ nucl-thhep-exhep-phnucl-exHyperfine Interact.(2018)·6 citations
28. 28*

    Probability of Warm Inflation in Loop Quantum Cosmology

    L. L. Graef🇧🇷 · Rudnei O. Ramos🇧🇷

    Warm inflation is analyzed in the context of Loop Quantum Cosmology (LQC). The bounce in LQC provides a mean through which a Liouville measure can be defined, which has been used previously to characterize the a priori probability for inflation in LQC. Here we take advantage of the tools provided by LQC to study instead the a priori probability for warm inflation dynamics in the context of a monomial quartic inflaton potential. We study not only the question of how a general warm inflation dynamics can be realized in LQC with an appropriate number of e-folds, but also how such dynamics is constrained to be in agreement with the latest cosmic microwave background radiation from Planck. The fraction of warm inflation trajectories in LQC that gives both the required minimum amount e-folds of expansion and also passes through the observational window of allowed values for the tensor-to-scalar ratio and the spectral tilt is explicitly obtained. We find that the probability of warm inflation with a monomial quartic potential in LQC is higher than that of cold inflation in the same context. Furthermore, we also obtain that the a priori probability gets higher as the inherent dissipation of the warm inflation dynamics increases.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2018)·31 citations
29. 29*

    Chiral observables and topology in hot QCD with two families of quarks

    Florian Burger🇩🇪 · Ernst-Michael Ilgenfritz🇷🇺 · Maria Paola Lombardo🇮🇹 · Anton Trunin🇷🇺

    We present results on QCD with four dynamical flavors in the temperature range $150$ MeV $\lesssim T\lesssim 500$ MeV. We have performed lattice simulations with Wilson fermions at maximal twist and measured Polyakov loop, chiral condensate and disconnected susceptibility, on lattices with spacings as fine as 0.065 fm. For most observables spacing effects are below statistical errors, which enables us to identify lattice results with continuum estimates. Our estimate of the pseudocritical temperature compares favorably with continuum results from staggered and domain wall fermions, confirming that a dynamical charm does not contribute in the transition region. From the high temperature behaviour of the disconnected chiral susceptibility we infer the topological susceptibility, which encodes relevant properties of the QCD axion, a plausible Dark Matter candidate. The topological susceptibility thus measured exhibits a power-law decay for $T/T_c\gtrsim 2$, with an exponent close to the one predicted by the Dilute Instanton Gas Approximation (DIGA). Close to $T_c$ the temperature dependent effective exponent seems to approach the DIGA result from above, a behaviour which would support recent analytic calculations based on an Instantons-dyons model. These results constrain the mass of a hypothetic QCD post-inflationary axion, once an assumption concerning the relative contribution of axions to Dark Matter is made.

    ↳ hep-lathep-phPRD(2018)·95 citations
30. 30*

    Large-$N_c$ Relationships Among Two-Derivative Pionless Effective Field Theory Couplings

    Matthias R. Schindler🇺🇸 · Hersh Singh🇺🇸 · Roxanne P. Springer🇺🇸

    We analyze two-derivative two-nucleon interactions in a combined pionless effective field theory and large-$N_c$ expansion. At leading order in the large-$N_c$ expansion, relationships among low-energy constants emerge. We find these to be consistent with experiment. However, it is critical to correctly address the subtraction-point dependence of the low-energy constants. These results provide additional confidence that the dual-expansion procedure is useful for analyzing low-energy few-body observables.

    ↳ nucl-thhep-phPRC(2018)·19 citations
31. 31*

    Determination of quark masses from ${\mathbf{n}}_{\mathbf{f}}=4$ lattice QCD and the RI-SMOM intermediate scheme

    A. T. Lytle🇬🇧 · C. T. H. Davies🇬🇧 · D. Hatton🇬🇧 · G. P. Lepage🇺🇸 · C. Sturm🇩🇪

    We determine the charm and strange quark masses in the $\overline{\text{MS}}$ scheme, using $n_f=2+1+1$ lattice QCD calculations with highly improved staggered quarks (HISQ) and the RI-SMOM intermediate scheme to connect the bare lattice quark masses to continuum renormalisation schemes. Our study covers analysis of systematic uncertainties from this method, including nonperturbative artefacts and the impact of the non-zero physical sea quark masses. We find $m_c^{\overline{\text{MS}}}(3\text{GeV})=0.9896(61)$ GeV and $m_s^{\overline{\text{MS}}}(3\text{GeV})=0.08536(85)$ GeV, where the uncertainties are dominated by the tuning of the bare lattice quark masses. These results are consistent with, and of similar accuracy to, those using the current-current correlator approach coupled to high-order continuum QCD perturbation theory, implemented in the same quark formalism and on the same gauge field configurations. This provides a strong test of the consistency of methods for determining the quark masses to high precision from lattice QCD. We also give updated lattice QCD world averages for $c$ and $s$ quark masses.

    ↳ hep-lathep-phPRD(2018)·59 citations
32. 32*

    Effective field theory of time-translational symmetry breaking in nonequilibrium open system

    Masaru Hongo🇯🇵 · Suro Kim🇯🇵 · Toshifumi Noumi🇯🇵 · Atsuhisa Ota🇳🇱

    We develop the effective field theoretical (EFT) approach to time-translational symmetry breaking of nonequilibrium open systems based on the Schwinger-Keldysh formalism. In the Schwinger-Keldysh formalism, all the symmetries of the microscopic Lagrangian are doubled essentially because the dynamical fields are doubled to describe the time-evolution along the closed-time-path. The effective Lagrangian for open systems are then obtained by coarse-graining the microscopic Schwinger-Keldysh Lagrangian. As a consequence of coarse-graining procedure, there appear the noise and dissipation effects, which explicitly break the doubled time-translational symmetries into a diagonal one. We therefore need to incorporate this symmetry structure to construct the EFT for Nambu-Goldstone bosons in symmetry broken phases of open systems. Based on this observation together with the consistency of the Schwinger-Keldysh action, we construct and study the general EFT for time-translational symmetry breaking in particular, having in mind applications to synchronization, time crystal, and cosmic inflation.

    ↳ hep-thastro-ph.COcond-mat.quant-gascond-mat.stat-mech+1JHEP(2019)·44 citations
33. 33*

    Heavy Quarkonium Dissociation by Thermal Gluons at Next-to-leading Order in the Quark-Gluon Plasma

    Shile Chen🇨🇳 · Min He🇨🇳

    Using the chromo-electric dipole coupling Hamiltonian from QCD multipole expansion, we derive the dissociation cross sections of heavy quarkonia by thermal gluons at next-to-leading order (NLO, also known as inelastic parton scattering dissociation) in the Quark-Gluon Plasma (QGP) in the framework of second order quantum mechanical perturbation theory. While suffering divergence (infrared and soft-collinear divergences) in vacuum, the cross sections thus derived become finite in the QGP as rendered by the finite thermal gluon masses. In contrast to the leading order (LO, also known as gluo-dissociation) counterparts rapidly dropping off with increasing incident gluon energy, the NLO cross sections exhibits finite value toward high energies because of new phase space being opened up. We then carry out a full calculation of the dissociation rates for various charmonia and bottomonia within a non-relativistic in-medium potential model. The NLO process is shown to dominate the dissociation rate toward high temperatures when the binding energies of heavy quarkonia become smaller relative to the Debye screening mass.

    ↳ nucl-thhep-phPLB(2018)·14 citations
34. 34*

    4d ensembles of percolating center vortices and monopole defects: the emergence of flux tubes with N-ality and gluon confinement

    L. E. Oxman🇧🇷

    Ensembles of magnetic defects represent quantum variables that have been detected and extensively explored in lattice $\mathrm{SU}(N)$ pure Yang-Mills theory. They successfully explain many properties of confinement and are strongly believed to capture the (infrared) path-integral measure. In this work, we initially motivate the presence of magnetic non-Abelian degrees of freedom in these ensembles. Next, we consider a simple Gaussian model to account for fluctuations. In this case, both center vortices and monopoles become relevant degrees in Wilson loop averages. These physical inputs are then implemented in an ensemble of percolating center vortices in four dimensions by proposing a measure to compute center-element averages. The introduction of phenomenological information such as monopole tension, stiffness, and fusion leads to an effective YMH model with adjoint Higgs fields. If monopoles also condense, then the gauge group undergoes $\mathrm{SU}(N)\to \mathrm{Z}(N)$ SSB. This pattern has been proposed as a strong candidate to describe confinement. In the presence of external quarks, these models are known to be dominated by classical solutions, formed by flux tubes with $N$-ality as well as by confined dual monopoles (gluons).

    ↳ hep-thhep-phPRD(2018)·28 citations
35. 35*

    Spontaneous symmetry breaking and the Goldstone theorem in non-Hermitian field theories

    Jean Alexandre🇬🇧 · John Ellis🇬🇧 · Peter Millington🇬🇧 · Dries Seynaeve🇬🇧

    We demonstrate the extension to PT-symmetric field theories of the Goldstone theorem, confirming that the spontaneous appearance of a field vacuum expectation value via minimisation of the effective potential in a non-Hermitian model is accompanied by a massless scalar boson. Laying a basis for our analysis, we first show how the conventional quantisation of the path-integral formulation of quantum field theory can be extended consistently to a non-Hermitian model by considering PT conjugation instead of Hermitian conjugation. The extension of the Goldstone theorem to a PT-symmetric field theory is made possible by the existence of a conserved current that does not, however, correspond to a symmetry of the non-Hermitian Lagrangian. In addition to extending the proof of the Goldstone theorem to a PT-symmetric theory, we exhibit a specific example in which we verify the existence of a massless boson at the tree and one-loop levels.

    ↳ hep-thhep-phquant-phPRD(2018)·71 citations
36. 36*

    Constraints on dark energy dynamics and spatial curvature from Hubble parameter and baryon acoustic oscillation data

    Joseph Ryan🇺🇸 · Sanket Doshi🇮🇳 · Bharat Ratra🇺🇸

    We use all available baryon acoustic oscillation distance measurements and Hubble parameter data to constrain the cosmological constant $\Lambda$, dynamical dark energy, and spatial curvature in simple cosmological models. We find that the consensus spatially flat $\Lambda$CDM model provides a reasonable fit to the data, but depending on the Hubble constant prior and cosmological model, it can be a little more than 1$\sigma$ away from the best-fit model, which can favor mild dark energy dynamics or non-flat spatial hypersurfaces.

    ↳ astro-ph.COgr-qchep-phhep-thMNRAS(2018)·116 citations
37. 37*

    New Perspective on Hybrid Mesons

    Shu-Sheng Xu🇨🇳 · Zhu-Fang Cui🇨🇳 · Lei Chang🇨🇳 · Joannis Papavassiliou🇪🇸 · Craig D. Roberts🇺🇸 · Hong-Shi Zong🇨🇳

    It is thought that strong interactions within the Standard Model can generate bound-states in which non-Abelian gauge-bosons play a dual role, serving both as force and matter fields. In this context we introduce a novel approach to the hybrid-meson (valence-gluon+quark+antiquark) bound-state problem in relativistic quantum field theory. Exploiting the existence of strong two-body correlations in the gluon-quark, $q_g=[gq]$, and gluon-antiquark, ${\bar{q}}_g=[g\bar{q}]$ channels, we argue that a sound description of hybrid properties can be obtained by solving a coupled-pair of effectively two-body equations; and, consequently, that hybrids may be viewed as highly-correlated $q_g\bar{q}\leftrightarrow q{\bar{q}}_g$ bound-states. Analogies may be drawn between this picture of hybrid structure and that of baryons, in which quark+quark (diquark) correlations play a key role. The potential of this formulation is illustrated by calculating the spectrum of light-quark isovector hybrid mesons.

    ↳ nucl-thhep-exhep-lathep-ph+1EPJA(2019)·33 citations
38. 38*

    The Cross Anomalous Dimension in Maximally Supersymmetric Yang--Mills Theory

    Hagen Münkler🇨🇭

    The cross or soft anomalous dimension matrix describes the renormalization of Wilson loops with a self-intersection and is an important object in the study of infrared divergences of scattering amplitudes. In this paper it is studied for the Maldacena--Wilson loop in N=4 supersymmetric Yang--Mills theory and Euclidean kinematics. We consider both the strong-coupling description in terms of minimal surfaces in AdS5 as well as the weak-coupling side up to the two-loop level. In either case, the coefficients of the cross anomalous dimension matrix can be expressed in terms of the cusp anomalous dimension. The strong-coupling description displays a Gross--Ooguri phase transition and we argue that the cross anomalous dimension is an interesting object to study in an integrability-based approach.

    ↳ hep-thhep-phJHEP(2018)·5 citations
39. 39*

    Visualizing Invisible Dark Matter Annihilation with the CMB and Matter Power Spectrum

    Yanou Cui🇺🇸 · Ran Huo🇺🇸

    We study the cosmological signatures of Invisibly Annihilating Dark Matter (IAnDM), where DM annihilates into dark radiation particles that are decoupled from the Standard Model (SM). In the simple benchmark model we consider here, such invisible annihilation determines the relic abundance of DM via dark thermal freeze-out. We demonstrate that IAnDM may reveal itself through observable, novel signatures that are correlated: scale-dependent $\Delta N_{\text{eff}}$ (number of extra effective neutrinos) in the Cosmic Microwave Background (CMB) spectrum due to DM residual annihilation, while the phase of acoustic peaks shifts towards the opposite direction relative to that due to SM neutrinos, resembling the effect due to scattering (fluidlike) thermal dark radiation; in addition, IAnDM induces modifications to the matter power spectrum that resemble those due to warm dark matter. Current data are sensitive to IAnDM with masses up to $\sim 200$ keV, while future observations will improve this reach, especially if the late-time DM annihilation cross section is enhanced relative to the standard thermal value, which can be realized in a variety of scenarios. This work also demonstrates a new possibility of realizing thermal sub-MeV DM with observable signals.

    ↳ astro-ph.COhep-phPRD(2019)·7 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.