Tue·Nov 17, 2015Tuesday·November 17, 2015

1. 01*

   Lepton-flavour violating decays in theories with dimension 6 operators

   Giovanni Marco Pruna🇨🇭 · Adrian Signer🇨🇭

   Despite a large experimental effort, so far no evidence for flavour-violating decays of charged leptons such as $l_i\to l_j\gamma$ and $l_i\to l_j{l}_k{l}_k$ has been found. The absence of a signal puts very severe constraints on many extensions of the Standard Model. Here we apply a model independent approach by studying such decays in the Standard Model effective field theory. Going beyond leading order in the Standard Model couplings and considering all dimension 6 operators that might lead to lepton-flavour violation, we are able to extract limits on a large number of Wilson coefficients of such operators. We are also able to compare the impact of particular searches and find, for example, that flavour-violating decays of the $Z$-boson $Z\to \mu e$ are much more constrained from low-energy experiments $\mu \to e\gamma$ than from the limits of current and future direct searches at high energy.

   hep-phEPJ Web Conf.(2016)·25 citations
2. 02*

   Constraints to Dark Matter from Inert Higgs Doublet Model

   Marco Aurelio Díaz🇨🇱 · Benjamin Koch🇨🇱 · Sebastián Urrutia-Quiroga🇨🇱

   We study the Inert Higgs Doublet Model and its inert scalar Higgs $H$ as the only source for dark matter. It is found that three mass regions of the inert scalar Higgs can give the correct dark matter relic density. The low mass region (between 3 and 50 GeV) is ruled out. New direct dark matter detection experiments will probe the intermediate (between 60 and 100 GeV) and high (heavier than 550 GeV) mass regions. Collider experiments are advised to search for $D^{\pm }\to H{W}^{\pm }$ decay in the two jets plus missing energy channel.

   hep-phAdv.High Energy Phys.(2016)·89 citations
3. 03*

   Quasi Distribution Amplitude of Heavy Quarkonia

   Yu Jia🇨🇳 · Xiaonu Xiong🇮🇹

   The recently-proposed quasi distributions point out a promising direction for lattice QCD to investigate the light-cone correlators, such as parton distribution functions (PDF) and distribution amplitudes (DA), directly in the $x$-space. Owing to its excessive simplicity, the heavy quarkonium can serve as an ideal theoretical laboratory to ascertain certain features of quasi-DA. In the framework of non-relativistic QCD (NRQCD) factorization, we compute the order-${\alpha }_s$ correction to both light-cone distribution amplitudes (LCDA) and quasi-DA associated with the lowest-lying quarkonia, with the transverse momentum UV cutoff interpreted as the renormalization scale. We confirm analytically that the quasi-DA of a quarkonium does reduce to the respective LCDA in the infinite-momentum limit. We also observe that, provided that the momentum of a charmonium reaches about 2-3 times its mass, the quasi-DAs already converge to the LCDAs to a decent level. These results might provide some useful guidance for the future lattice study of the quasi distributions.

   hep-phhep-latPRD(2016)·23 citations
4. 04*

   Heavy Higgs Coupled to Vector-like Quarks: Strong CP Problem and Search Prospects at the 14 TeV LHC

   Alexandre Alves🇧🇷 · D. A. Camargo🇧🇷 · Alex G. Dias🇧🇷

   Motivated by a solution to the strong CP problem we propose a model where a new heavy neutral CP-even Higgs boson couples to vector-like quarks enhancing its production cross section whose dominant decays are into weak bosons. The masses of the vector-like quarks are generated through interactions with a singlet scalar field charged under a broken global $U(1)$ symmetry providing a solution to the strong CP problem by means of the Peccei-Quinn mechanism. The diboson excess observed by the ATLAS Collaboration is discussed as the new heavy Higgs boson is a candidate to explain a possible signal in this channel. We also show that the 14 TeV LHC is capable of discovering this heavy Higgs with masses up to 1 TeV in the $H\to ZZ\to {\ell }^{+}{\ell }^{-}{\ell }^{\prime +}{\ell }^{\prime -}$ search channel using boosted decision trees to better discriminate between signals and backgrounds and to tame systematic uncertainties in the background rates.

   hep-phPRD(2016)·5 citations
5. 05*

   Signatures from Scalar Dark Matter with a Vector-like Quark Mediator

   Federica Giacchino🇧🇪 · Alejandro Ibarra🇩🇪 · Laura Lopez Honorez🇧🇪 · Michel H.G. Tytgat🇧🇪 · Sebastian Wild🇩🇪

   We present a comprehensive study of a model where the dark matter is composed of a singlet real scalar that couples to the Standard Model predominantly via a Yukawa interaction with a light quark and a colored vector-like fermion. A distinctive feature of this scenario is that thermal freeze-out in the early universe may be driven by annihilation both into gluon pairs at one-loop ($gg$) and by virtual internal Bremsstrahlung of a gluon ($q\bar{q}g$). Such a dark matter candidate may also be tested through direct and indirect detection and at the LHC; viable candidates have either a mass nearly degenerate with that of the fermionic mediator or a mass above about 2 TeV.

   hep-phastro-ph.COJCAP(2016)·81 citations
6. 06*

   Minimal Natural Supersymmetry after the LHC8

   M. Drees🇩🇪 · J. S. Kim🇪🇸

   In this work, we present limits on natural supersymmetry scenarios based on searches in data taken during run 1 of the LHC. We consider a set of 22000 model points in a six dimensional parameter space. These scenarios are minimal in the sense of only keeping those superparticles relatively light that are required to cancel the leading quadratically divergent quantum corrections (from the top and QCD sector) to the Higgs mass in the Standard Model. The resulting mass spectra feature higgsinos as the lightest supersymmetric particle, as well as relatively light third generation $SU(2)$ doublet squarks and $SU(2)$ singlet stops and gluinos while assuming a Standard Model like Higgs boson. All remaining supersymmetric particles and Higgs bosons are assumed to be decoupled. We check each parameter set against a large number of LHC searches as implemented in the public code {\tt CheckMATE}. These searches show a considerable degree of complementarity, i.e. in general many searches have to be considered in order to check whether a given scenario is allowed. We delineate allowed and excluded regions in parameter space. For example, we find that all scenarios where either $m_{{\tilde{t}}_1}<230$ GeV or $m_{\tilde{g}}<440$ GeV are clearly excluded, while all model points where $m_{{\tilde{t}}_1}>660$ GeV and $m_{\tilde{g}}>1180$ GeV remain allowed.

   hep-phhep-exPRD(2016)·43 citations
7. 07*

   Leading-order hadronic contribution to the electron and muon g-2

   Fred Jegerlehner🇩🇪

   I present a new data driven update of the hadronic vacuum polarization effects for the muon and the electron $g-2$. For the leading order contributions I find $a_{\mu }^{\mathrm{had}(1)}=(686.99\pm 4.21)[687.19\pm 3.48]\times 10^{-10}$ based on $e^{+}{e}^{-}$data [incl. $\tau$ data], $a_{\mu }^{\mathrm{had}(2)}=(-9.934\pm 0.091)\times 10^{-10}$ (NLO) and $a_{\mu }^{\mathrm{had}(3)}=(1.226\pm 0.012)\times 10^{-10}$ (NNLO) for the muon, and $a_e^{\mathrm{had}(1)}=(184.64\pm 1.21)\times 10^{-14}$ (LO), $a_e^{\mathrm{had}(2)}=(-22.10\pm 0.14)\times 10^{-14}$ (NLO) and $a_e^{\mathrm{had}(3)}=(2.79\pm 0.02)\times 10^{-14}$ (NNLO) for the electron. A problem with vacuum polarization undressing of cross-sections (time-like region) is addressed. I also add a comment on properly including axial mesons in the hadronic light-by-light scattering contribution. My estimate here reads $a_{\mu }[a_1,f_1^{\prime },f_1]\sim (7.51\pm 2.71)\times 10^{-11}.$ With these updates $a_{\mu }^{\exp }-a_{\mu }^{\mathrm{the}}=(32.73\pm 8.15)\times 10^{-10}$ a 4.0 $\sigma$ deviation, while $a_e^{\exp }-a_e^{\mathrm{the}}=(-1.10\pm 0.82)\times 10^{-12}$ shows no significant deviation.

   hep-phEPJ Web Conf.(2016)·89 citations
8. 08*

   Boson Stars from Self-Interacting Dark Matter

   Joshua Eby🇺🇸 · Chris Kouvaris🇩🇰 · Niklas Grønlund Nielsen🇩🇰 · L.C.R. Wijewardhana🇺🇸

   We study the possibility that self-interacting bosonic dark matter forms star-like objects. We study both the case of attractive and repulsive self-interactions, and we focus particularly in the parameter phase space where self-interactions can solve well standing problems of the collisionless dark matter paradigm. We find the mass radius relations for these dark matter bosonic stars, their density profile as well as the maximum mass they can support.

   hep-phastro-ph.COJHEP(2016)·183 citations
9. 09*

   D meson mass increase by restoration of chiral symmetry in nuclear matter

   Kei Suzuki🇯🇵 · Philipp Gubler🇮🇹 · Makoto Oka🇯🇵

   Spectral functions of the pseudoscalar $D$ meson in the nuclear medium are analyzed using QCD sum rules and the maximum entropy method. This approach enables us to extract the spectral functions without any phenomenological assumption, and thus to visualize in-medium modification of the spectral functions directly. It is found that the reduction of the chiral condensates of dimension 3 and 5 causes the masses of both $D^{+}$ and $D^{-}$ mesons to grow gradually at finite density. Additionally, we construct charge-conjugate-projected sum rules and find a $D^{+}$-$D^{-}$ mass splitting of about -15 MeV at nuclear saturation density.

   hep-phnucl-thPRC(2016)·55 citations
10. 10*

    Deeply Virtual Meson Production on the nucleon

    L. Favart🇧🇪 · M. Guidal🇫🇷 · T. Horn🇺🇸 · P. Kroll🇩🇪

    We review the status of the data and phenomenology in the Generalized Parton Distribution approach of Deep Virtual Meson Production.

    hep-phEPJA(2016)·105 citations
11. 11*

    Estimates of Z'couplings within data on the A_{FB} for Drell-Yan process at the LHC at s^(1/2) = 7 TeV and 8 TeV

    A. Pevzner🇺🇦 · V. Skalozub🇺🇦

    Model-independent search for the Abelian Z' gauge boson in the Drell-Yan process at the LHC at s^{1/2}= 7 TeV and 8 TeV is fulfilled. Estimations of the Z' axial-vector coupling a_f^2 to the standard model fermions, the couplings of the axial-vector to lepton vector currents a_f v_l and the couplings of the axial-vector to quark vector currents a_f v_q are derived within data on the forward-backward asymmetry presented by the CMS Collaboration. The analysis takes into consideration the behaviour of the differential cross-section which exhibits itself if the derived already special relations between the couplings proper to the renormalizable theories are accounted for. In particular, they hold in all the models of Abelian Z' usually considered in the model-dependent analysis of the LHC data. The coupling values are estimated at ~ 92 % CL by means of the maximum likelihood function. They weakly depend on the Z' mass in the investigated interval 1.2 TeV < m_Z' < 5 TeV. Taking into account the dependence of Z-Z' mixing angle theta_0 on m_Z' and the LEP constraints |theta_0|~ 10^{-3}-10^{-4}, the optimistic limits on m_{Z'} are established as 3 < m_Z' < 7-8 TeV. Comparison with the results of other authors is given.

    hep-phPRD(2016)·4 citations
12. 12*

    Mesons beyond the quark-antiquark picture

    Francesco Giacosa🇩🇪

    The vast majority of mesons can be understood as quark-antiquark states. Yet, various other possibilities exists: glueballs (bound-state of gluons), hybrids (quark-antiquark plus gluon), and four-quark states (either as diquark-antidiquark or molecular objects) are expected. In particular, the existence of glueballs represents one of the first predictions of QCD, which relies on the nonabelian feature of its structure; this is why the search for glueballs and their firm discovery would be so important, both for theoretical and experimental developments. At the same time, many new resonances ($X,Y,$ and $Z$ states) were discovered experimentally, some of which can be well understood as four-quark objects. In this lecture, we review some basic aspects of QCD and show in a pedagogical way how to construct an effective hadronic model of QCD. We then present the results for the decays of the scalar and the pseudoscalar glueballs within this approach and discuss the future applications to other glueball states. In conclusion, we briefly discuss the status of four-quark states, both in the low-energy domain (light scalar mesons) as well as in the high-energy domain (in the charmonia region).

    hep-phActa Phys.Polon.B(2016)·7 citations
13. 13*

    Three-loop hard-thermal-loop perturbation theory thermodynamics at finite temperature and finite baryonic and isospin chemical potential

    Jens O. Andersen🇳🇴 · Najmul Haque🇺🇸 · Munshi G. Mustafa🇮🇳 · Michael Strickland🇺🇸

    In a previous paper (JHEP {\bf 05} (2014) 27), we calculated the three-loop thermodynamic potential of QCD at finite temperature $T$ and quark chemical potentials ${\mu }_q$ using the hard-thermal-loop perturbation theory (HTLpt) reorganization of finite temperature and density QCD. The result allows us to study the thermodynamics of QCD at finite temperature and isospin chemical potential ${\mu }_I$. We calculate the pressure, energy density, and entropy density, the trace anomaly, and the speed of sound at zero and nonzero ${\mu }_I$. The second, fourth, and sixth-order isospin susceptibilities are calculated at zero ${\mu }_I$. Our results can be directly compared to lattice QCD without Taylor expansions around ${\mu }_q=0$ since QCD has no sign problem at finite isospin chemical potential.

    hep-phhep-latPRD(2016)·72 citations
14. 14*

    Study on direct pion emission in decay $D^{\ast +}\to D^{+}\pi$

    Xing-Dao Guo🇨🇳 · Xuewen Liu🇨🇳 · Hong-Wei Ke🇨🇳 · Xue-Qian Li🇨🇳

    The QCD multipole expansion (QCDME) is based on the quantum field theory, so should be more reliable. However, on another aspect, it refers to the non-perturbative QCD , so that has a certain application range. Even though it successfully explains the data of transition among members of the ${\rm Y}$ ($\psi$) family, as Eichten indicates, beyond the production threshold of mediate states it fails to meet data by several orders. In this work, by studying a simple decay mode $D^{\ast }\to D+{\pi }^0$, where a pion may be emitted before $D^{\ast }$ transiting into $D$, we analyze the contribution of QCD multipole expansion. Whereas as the $D\pi$ portal is open, the dominant contribution is an OZI allowed process where a light quark-pair is excited out from vacuum and its contribution can be evaluated by the ${}^3{P}_0$ model. Since the direct pion emission is a process which is OZI suppressed and violates the isospin conservation, its contribution must be much smaller than the dominant one. By a careful calculation, we may quantitatively estimate how small the QCDME contribution should be and offer a quantitative interpretation for Eichten's statement.

    hep-phCPC(2016)·0 citations
15. 15*

    Implications of a Light "Dark Higgs" Solution to the $g_{\mu }-2$ Discrepancy

    Chien-Yi Chen🇨🇦 · Hooman Davoudiasl🇺🇸 · William J. Marciano🇺🇸 · Cen Zhang🇺🇸

    A light scalar $\varphi$ with mass $\lesssim 1$ GeV and muonic coupling $\mathcal{O}(10^{-3})$ would explain the 3.5 $\sigma$ discrepancy between the Standard Model (SM) muon $g-2$ prediction and experiment. Such a scalar can be associated with a light remnant of the Higgs mechanism in the "dark" sector. We suggest $\varphi \to l^{+}{l}^{-}$ bump hunting in $\mu \to e\nu \bar{\nu }\varphi$, ${\mu }^{-}p\to {\nu }_{\mu }n\varphi$ (muon capture), and $K^{\pm }\to {\mu }^{\pm }\nu \varphi$ decays as direct probes of this scenario. In a general setup, a potentially observable muon electric dipole moment $\lesssim 10^{-23}e\cdot \text{cm}$ and lepton flavor violating decays $\tau \to \mu (e)\varphi$ or $\mu \to e\varphi$ can also arise. Depending on parameters, a deviation in BR($H\to {\mu }^{+}{\mu }^{-}$) from SM expectations, due to Higgs coupling misalignment, can result. We illustrate how the requisite interactions can be mediated by weak scale vector-like leptons that typically lie within the reach of future LHC measurements.

    hep-phhep-exPRD(2016)·108 citations
16. 16*

    Strong decay patterns of the hidden-charm pentaquark states $P_c(4380)$ and $P_c(4450)$

    Guang-Juan Wang🇨🇳 · Li Ma🇨🇳 · Xiang Liu🇨🇳 · Shi-Lin Zhu🇨🇳

    With the heavy quark symmetry and spin rearrangement scheme, we study the strong decay behavior of the hidden-charm pentaquark states with $J^P={\frac{3}{2}}^{\pm },{\frac{5}{2}}^{\pm }$ assuming they are molecular candidates composed of ${\bar{D}}^{(\ast )}$ and ${\Sigma }_c^{(\ast )}$. We obtain several typical ratios of the partial decay widths of the hidden-charm pentaquarks. For the three S-wave $(\bar{D}{\Sigma }_c^{\ast })$, $({\bar{D}}^{\ast }{\Sigma }_c)$ and $({\bar{D}}^{\ast }{\Sigma }_c^{\ast })$ molecular pentaquarks with $J^P={3/2}^{-}$, we have obtained the ratio of their $J/\psi N$ decay widths: $\Gamma \left[(\bar{D}{\Sigma }_c^{\ast })\right]:\Gamma \left[({\bar{D}}^{\ast }{\Sigma }_c)\right]:\Gamma \left[({\bar{D}}^{\ast }{\Sigma }_c^{\ast })\right]=2.7:1.0:5.4$, which may be useful to further test the possible molecular assignment of the $P_c$ states.

    hep-phhep-exhep-latnucl-thPRD(2016)·32 citations
17. 17*

    Production of associated ${\chi }_b$ and open charm at the LHC

    A.K. Likhoded🇷🇺 · A.V. Luchinsky🇷🇺 · S.V. Poslavsky🇷🇺

    In the present paper we study the production of ${\chi }_b+c\bar{c}$ at the LHC within single parton scattering approach. A special attention payed to the feed-down from ${\chi }_b$ states to the associated ${\rm Y}+c\bar{c}$ production, which was recently studied by the LHCb. We have found that this feed-down is about percents of the total cross section seen in the experiment. It is shown that the shapes of the differential distributions are almost same as found by the LHCb except the azimuthal asymmetry, which is almost flat in the experiment. We conclude that the precise study of the single parton scattering contributions is necessary for the correct isolation of other possible production channels such as double parton scattering.

    hep-phPLB(2016)·6 citations
18. 18*

    Renormalization-Scale Uncertainty in the Decay Rate of False Vacuum

    Motoi Endo🇯🇵 · Takeo Moroi🇯🇵 · Mihoko M. Nojiri🇯🇵 · Yutaro Shoji🇯🇵

    We study radiative corrections to the decay rate of false vacua, paying particular attention to the renormalization-scale dependence of the decay rate. The decay rate exponentially depends on the bounce action. The bounce action itself is renormalization scale dependent. To make the decay rate scale-independent, radiative corrections, which are due to the field fluctuations around the bounce, have to be included. We show quantitatively that the inclusion of the fluctuations suppresses the scale dependence, and hence is important for the precise calculation of the decay rate. We also apply our analysis to a supersymmetric model and show that the radiative corrections are important for the Higgs-stau system with charge breaking minima.

    hep-phJHEP(2016)·20 citations
19. 19*

    Decay $B\to K^{\ast }(\to K\pi ){\ell }^{+}{\ell }^{-}$ in covariant quark model

    Stanislav Dubnička🇸🇰 · Anna Z. Dubničková🇸🇰 · Nurgul Habyl🇰🇿 · Mikhail A. Ivanov🇷🇺 · Andrej Liptaj🇸🇰 · Guliya S. Nurbakova🇰🇿

    Our article is devoted to the study of the rare $B\to K^{\ast }{\ell }^{+}{\ell }^{-}$~decay where $\ell =e,\mu ,\tau$. We compute the relevant form factors in the framework of the covariant quark model with infrared confinement in the full kinematical momentum transfer region. The calculated form factors are used to evaluate branching fractions and polarization observables in the cascade decay $B\to K^{\ast }(\to K\pi ){\ell }^{+}{\ell }^{-}$. We compare the obtained results with available experimental data and the results from other theoretical approaches.

    hep-phhep-exnucl-thFew Body Syst.(2016)·15 citations
20. 20*

    Detecting electron neutrinos from solar dark matter annihilation by JUNO

    Wan-Lei Guo🇨🇳

    We explore the electron neutrino signals from light dark matter (DM) annihilation in the Sun for the large liquid scintillator detector JUNO. In terms of the spectrum features of three typical DM annihilation channels $\chi \chi \to \nu \bar{\nu },{\tau }^{+}{\tau }^{-},b\bar{b}$, we take two sets of selection conditions to calculate the expected signals and atmospheric neutrino backgrounds based on the Monte Carlo simulation data. Then the JUNO sensitivities to the spin independent DM-nucleon and spin dependent DM-proton cross sections are presented. It is found that the JUNO projected sensitivities are much better than the current spin dependent direct detection experimental limits for the $\nu \bar{\nu }$ and ${\tau }^{+}{\tau }^{-}$ channels. In the spin independent case, the JUNO will give the better sensitivity to the DM-nucleon cross section than the LUX and CDMSlite limits for the $\nu \bar{\nu }$ channel with the DM mass lighter than 6.5 GeV. If the $\nu \bar{\nu }$ or ${\tau }^{+}{\tau }^{-}$ channel is dominant, the future JUNO results are very helpful for us to understand the tension between the DAMA annual modulation signal and other direct detection exclusions.

    hep-phastro-ph.HEhep-exJCAP(2016)·13 citations
21. 21*

    A data-driven approach to ${\pi }^0,\eta$ and ${\eta }^{\prime }$ single and double Dalitz decays

    Rafel Escribano🇪🇸 · Sergi Gonzàlez-Solís🇪🇸

    The dilepton invariant mass spectra and integrated branching ratios of the single and double Dalitz decays $\mathcal{P}\to {\ell }^{+}{\ell }^{-}\gamma$ and $\mathcal{P}\to {\ell }^{+}{\ell }^{-}{\ell }^{+}{\ell }^{-}$ ($\mathcal{P}={\pi }^0,\eta ,{\eta }^{\prime }$; $\ell =e$ or $\mu$) are predicted by means of a data-driven approach based on the use of rational approximants applied to ${\pi }^0,\eta$ and ${\eta }^{\prime }$ transition form factor experimental data in the space-like region.

    hep-phhep-exCPC(2018)·54 citations
22. 22*

    Imprints of a critical point on photon emission

    Falk Wunderlich🇩🇪 · Burkhard Kampfer🇩🇪

    The linear sigma model with linearized fluctuations of all involved fields facilitates the onset of a sequence of first-order phase transitions at a critical point. This phase structure has distinctive imprints on the photon emission rates. We argue that analogously a critical point in the QCD phase diagram manifests itself by peculiarities of the photon spectra, in particular when the dynamical expansion path of matter crosses the phase transition curve in the vicinity of the critical point.

    hep-phEPJA(2016)·2 citations
23. 23*

    Hyperfine splitting in the bottomonium system on the lattice and in the continuum

    Nikolai Zerf🇩🇪

    The latest experimental measurements of the hyperfine splitting $E_{\mathrm{hfs}}=M_{{\rm Y}(1S)}-M_{{\eta }_b(1S)}$ done by the Belle collaboration and the perturbative and lattice QCD predictions show a tension with the current extraction within lattice non-relativistic QCD. In this talk we revise the analysis of radiative corrections to the bottomonium hyperfine splitting within lattice non-relativistic QCD at the next-to-leading order. The result of the analysis is in good agreement with the perturbative and lattice QCD result as well as the direct measurement.

    hep-phPoS(2015)·0 citations
24. 24*

    Suppressing the QCD Axion Abundance by Hidden Monopoles

    Masahiro Kawasaki🇯🇵 · Fuminobu Takahashi🇯🇵 · Masaki Yamada🇯🇵

    We study the Witten effect of hidden monopoles on the QCD axion dynamics, and show that its abundance as well as isocurvature perturbations can be significantly suppressed if there is a sufficient amount of hidden monopoles. When the hidden monopoles make up a significant fraction of dark matter, the Witten effect suppresses the abundance of axion with the decay constant smaller than $10^{12}$ GeV. The cosmological domain wall problem of the QCD axion can also be avoided, relaxing the upper bound on the decay constant when the Peccei-Quinn symmetry is spontaneously broken after inflation.

    hep-phastro-ph.COPLB(2016)·78 citations
25. 25*

    A Three-Flavor Chiral Effective Model with Four Baryonic Multiplets within the Mirror Assignment

    Lisa Olbrich🇩🇪 · Miklós Zétényi🇩🇪 · Francesco Giacosa🇩🇪 · Dirk H. Rischke🇩🇪

    In the case of three quark flavors, (pseudo)scalar diquarks transform as antiquarks under chiral transformations. We construct four spin-1/2 baryonic multiplets from left- and right-handed quarks as well as left- and right-handed diquarks. The fact that two of these multiplets transform in a "mirror" way allows for chirally invariant mass terms. We then embed these baryonic multiplets into the Lagrangian of the so-called extended Linear Sigma Model, which features (pseudo)scalar and (axial-)vector mesons, as well as glueballs. Reducing the Lagrangian to the two-flavor case, we obtain four doublets of nucleonic states. These mix to produce four experimentally observed states with definite parity: the positive-parity nucleon $N(939)$ and Roper resonance $N(1440)$, as well as the negative-parity resonances $N(1535)$ and $N(1650)$. We determine the parameters of the nucleonic part of the Lagrangian from a fit to masses and decay properties of the aforementioned states. Studying the limit of vanishing quark condensate, we conclude that $N(939)$ and $N(1535)$, as well as $N(1440)$ and $N(1650)$ form pairs of chiral partners.

    hep-phnucl-thPRD(2016)·37 citations
26. 26*

    Flavor constraints on the Two Higgs Doublet Models of $Z_2$ symmetric and aligned types

    Tetsuya Enomoto🇯🇵 · Ryoutaro Watanabe🇰🇷

    We give a comprehensive study from flavor observables of pion, kaon, D_(s), and B_(s) mesons for limiting the Two Higgs Doublet Models (2HDMs) with natural flavor conservation, namely, Z_2 symmetric and aligned type of models. With use of the updated studies and analyses of B -> tau nu, D -> mu nu, D_s -> tau nu, D_s -> mu nu, K -> mu nu, Pi -> mu nu, B^0_s -> mu^+ mu^-, B^0_d -> mu^+ mu^-, tau -> K nu, tau -> Pi nu, B -> X_s gamma, K-K bar mixing, B^0_d-B^0_d bar mixing, and B^0_s-B^0_s bar mixing, we obtain constraints on the parameters in the 2HDMs. To calculate the constraints, we pay attention to a determination of CKM matrix elements and re-fit them to experimental data so that new contributions from additional Higgs bosons do not affect the determination. In addition, we discuss excesses of observables in the muon anomalous magnetic moment and the semi-tauonic B meson decays in the context of the 2HDM.

    hep-phJHEP(2016)·142 citations
27. 27*

    Experiment summary

    Andrea Rossi (Padua University & INFN)🇮🇹

    The measurement of the production of particles coming from hard scattering processes covers a fundamental role in the characterization of the system formed in heavy-ion collisions, allowing to probe the microscopic processes underlying the interaction of high energy partons with the medium. An impressive amount of measurements related to jet, quarkonia, open heavy flavor, and electroweak signal production in nucleus-nucleus as well as p(d)-nucleus collisions was delivered by experiments at RHIC and LHC in past years. In these proceedings, the main experimental results presented during the Hard Probes conference are summarized.

    ↳ hep-exhep-phnucl-exnucl-thNucl.Part.Phys.Proc.(2016)·0 citations
28. 28*

    Holographic renormalisation group flows and renormalisation from a Wilsonian perspective

    J. M. Lizana🇪🇸 · T. R. Morris🇬🇧 · M. Perez-Victoria🇪🇸

    From the Wilsonian point of view, renormalisable theories are understood as submanifolds in theory space emanating from a particular fixed point under renormalisation group evolution. We show how this picture precisely applies to their gravity duals. We investigate the Hamilton-Jacobi equation satisfied by the Wilson action and find the corresponding fixed points and their eigendeformations, which have a diagonal evolution close to the fixed points. The relevant eigendeformations are used to construct renormalised theories. We explore the relation of this formalism with holographic renormalisation. We also discuss different renormalisation schemes and show that the solutions to the gravity equations of motion can be used as renormalised couplings that parametrise the renormalised theories. This provides a transparent connection between holographic renormalisation group flows in the Wilsonian and non-Wilsonian approaches. The general results are illustrated by explicit calculations in an interacting scalar theory in AdS space.

    ↳ hep-thhep-phJHEP(2016)·29 citations
29. 29*

    Transport Theory of Heavy Flavor in Relativistic Nuclear Collisions

    Shanshan Cao🇺🇸

    A short overview is presented for the recent progress in the theory of heavy flavor transport in ultra-relativistic nuclear collisions, including a summary of different transport models, their phenomenological results of heavy meson quenching and flow at RHIC and LHC, a possible solution to the $R_{\mathrm{AA}}$ vs. $v_2$ puzzle and predictions for heavy flavor observables beyond the current measurements.

    ↳ nucl-thhep-phNucl.Part.Phys.Proc.(2016)·3 citations
30. 30*

    Nucleon axial and tensor charges with dynamical overlap quarks

    N. Yamanaka🇯🇵 · H. Ohki🇺🇸 · S. Hashimoto🇯🇵 · T. Kaneko🇯🇵

    We report on our calculation of the nucleon axial and tensor charges in 2+1-flavor QCD with dynamical overlap quarks. Gauge ensembles are generated at a single lattice spacing 0.12 fm and at a strange quark mass close to its physical value. We employ the all-mode-averaging technique to calculate the relevant nucleon correlation functions, and the disconnected quark loop is efficiently calculated by using the all-to-all quark propagator. We present our preliminary results for the isoscalar and isovector charges obtained at pion masses $m_{\pi }$ = 450 and 540 MeV.

    ↳ hep-lathep-phnucl-thPoS(2016)·11 citations
31. 31*

    Quartet-metric general relativity: scalar graviton, dark matter and dark energy

    Yury F. Pirogov🇷🇺

    General Relativity extended through a dynamical scalar quartet is proposed as a theory of the scalar-vector-tensor gravity, generically describing the unified gravitational dark matter (DM) and dark energy (DE). The implementation in the weak-field limit of the Higgs mechanism for the gravity, with a redefinition of metric field, is exposed in a generally covariant form. Under a natural restriction on parameters, the redefined theory possesses in the linearized approximation by a residual transverse-diffeomorphism invariance, and consistently comprises the massless tensor graviton and a massive scalar one as a DM particle. A number of the adjustable parameters in the full nonlinear theory and a partial decoupling of the latter from its weak-field limit noticeably extend the perspectives for the unified description of the gravity DM and DE in the various phenomena at the different scales.

    ↳ gr-qcastro-ph.COhep-phEPJC(2016)·12 citations
32. 32*

    Recent developments in neutron-proton scattering with Lattice Effective Field Theory

    Jose Manuel Alarcón🇩🇪

    In this contribution, we show some recent progress in the study of neutron-proton scattering with Nuclear Lattice Effective Field Theory (NLEFT). We present preliminary studies of both, the uncertainties in the $np$ phase shifts extracted with NLEFT, and the lattice spacing dependence in the transfer matrix formalism. Such investigations have not been performed before in the literature, and will be relevant for Monte Carlo simulations of nuclear structure with NLEFT.

    ↳ nucl-thhep-lathep-phPoS(2016)·0 citations
33. 33*

    Entropy of the Information Retrieved from Black Holes

    Laura Mersini-Houghton🇺🇸

    The retrieval of black hole information was recently presented in two interesting proposals in the 'Hawking Radiation' conference: a revised version by G. 't Hooft of a proposal he initially suggested 20 years ago and, a new proposal by S. Hawking. Both proposals address the problem of black hole information loss at the classical level and derive an expression for the scattering matrix. The former uses gravitation back reaction of incoming particles that imprints its information on the outgoing modes. The latter uses supertranslation symmetry of horizons to relate a phase delay of the outgoing wave packet compared to their incoming wave partners. The difficulty in both proposals is that the entropy obtained from them appears to be infinite. By including quantum effects into the Hawking and 't Hooft's proposals, I show that a subtlety arising from the inescapable measurement process, the Quantum Zeno Effect, not only tames divergences but it actually recovers the correct $1/4$ of the area Bekenstein-Hawking entropy law of black holes.

    ↳ hep-thgr-qchep-phquant-phClass.Quant.Grav.(2016)·4 citations
34. 34*

    Enhanced effects of the Lorentz invariance and Einstein equivalence principle violation in 229Th nuclear transition

    V.V. Flambaum🇦🇺

    The Lorentz invariance and Einstein equivalence principle violating effects in the narrow 7.8 eV transition in 229Th nucleus may be 100 000 times larger than in atoms. This transition may be investigated using high precision laser spectroscopy methods, has a very small width, and suppressed systematic effects. Similar values of the effects are expected in 73 eV 235U nuclear transition which is coming within the reach of the laser spectroscopy. Mossbauer transitions give another possibility.

    ↳ nucl-thgr-qchep-phphysics.atom-ph1 citation
35. 35*

    Nuclear physics from QCD on lattice

    Takashi Inoue · for HAL QCD Collaboration

    We have presented a strategy to study nuclei and nuclear matters from first principles, namely, from QCD. We first compute nucleon-nucleon potentials numerically in lattice QCD, and then use them to investigate properties of nuclei and nuclear matter by various methods developed in nuclear physics. As a demonstration that this strategy works, mass and structure of ^4^He, ^16^O and ^40^Ca, and equation of state of nuclear matters are determined with the lattice QCD induced two-nucleon potentials in a heavy quark region as an input. We have found that these nuclei and the symmetric nuclear matter are bound at one quark mass corresponding to the pseudo-scalar meson (pion) mass of 469 MeV (the octet baryon (nucleon) mass of 1161 MeV). The obtained binding energy per nucleon has a uniform mass-number A dependence which is consistent to the Bethe-Weizsacker mass formula qualitatively. The present study demonstrates that our strategy works well to investigate various properties of atomic nuclei and nuclear matter starting from QCD, without depending on models or experimental information about the nuclear force.

    ↳ hep-lathep-phnucl-exnucl-thPoS(2016)·6 citations
36. 36*

    D -> \pi l \nu and D -> K l \nu form factors with Nf=2+1+1 Twisted fermions

    N. Carrasco🇮🇹 · P. Lami🇮🇹 · V. Lubicz🇮🇹 · E. Picca🇮🇹 · L. Riggio🇮🇹 · S. Simula🇮🇹 · C. Tarantino🇮🇹

    We present a lattice QCD determination of the vector and scalar form factors of the semileptonic decays D->\pi l \nu and D -> K l \nu which are relevant for the extraction of the CKM matrix elements |Vcd| and |Vcs| from experimental data. Our analysis is based on the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2+1+1 dynamical fermions. We simulated at three different values of the lattice spacing and with pion masses as small as 210 MeV. Our preliminary estimates for the vector form factor at zero 4-momentum transfer are f+(D -> \pi)(0) = 0.610 (23) and f+(D -> K)(0) = 0.747 (22), where the uncertainties are only statistical. By combining our results with the experimental values of f+(D -> \pi)(0) |Vcd| and f+(D -> K)(0) |Vcs| we obtain |Vcd| = 0.2336 (93) and |Vcs| = 0.975 (30), which together with the PDG determination of |Vcb| are in agreement with the unitarity constraint of the Standard Model.

    ↳ hep-lathep-phPoS(2016)·11 citations
37. 37*

    Momentum dependence of kaon semileptonic form factors with Nf=2+1+1 Twisted Mass fermions

    N. Carrasco🇮🇹 · P. Lami🇮🇹 · V. Lubicz🇮🇹 · L. Riggio🇮🇹 · S. Simula🇮🇹

    We present a lattice QCD determination of the vector and scalar form factors of the kaon semileptonic decay $K\to \pi \ell \nu$, which is relevant for the determination of the CKM matrix element $|V_{us}|$ from experimental data. Our results are based on the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2+1+1 dynamical fermions. We simulated at three different values of the lattice spacing and with pion masses as small as 210 MeV. Our estimate for the vector form factor at zero 4-momentum transfer is $f_{+}(0)=0.9709(46)$, where the uncertainty is both statistical and systematic. By combining our result with the latest experimental value of $f_{+}(0)|V_{us}|$ we obtain $|V_{us}|=0.2230(11)$, which satisfies the unitarity constraint of the Standard Model at the permille level using the updated determination of $|V_{ud}|$ coming from superallowed nuclear $\beta$ decays. We present also the momentum dependence of the vector and scalar form factors in the whole range of values of the squared 4-momentum transfer measured in $K_{\ell 3}$ decays, obtaining a good agreement with the experimental data.

    ↳ hep-lathep-phPoS(2016)·4 citations
38. 38*

    Perturbative versus non-perturbative decoupling of heavy quarks

    Francesco Knechtli🇩🇪 · Mattia Bruno🇺🇸 · Jacob Finkenrath🇨🇾 · Björn Leder🇩🇪 · Rainer Sommer🇩🇪

    We simulate a theory with $N_f=2$ heavy quarks of mass $M$. At energies much smaller than $M$ the heavy quarks decouple and the theory can be described by an effective theory which is a pure gauge theory to leading order in $1/M$. We present results for the mass dependence of ratios such as $t_0(M)/t_0(0)$. We compute these ratios from simulations and compare them to the perturbative prediction. The latter relies on a factorisation formula for the ratios which is valid to leading order in $1/M$.

    ↳ hep-lathep-phPoS(2016)·6 citations
39. 39*

    Leading-twist parton distribution amplitudes of S-wave heavy-quarkonia

    Minghui Ding🇨🇳 · Fei Gao🇨🇳 · Lei Chang🇨🇳 · Yu-Xin Liu🇨🇳 · Craig D. Roberts🇺🇸

    The leading-twist parton distribution amplitudes (PDAs) of ground-state ${}^1{S}_0$ and ${}^3{S}_1$ $c\bar{c}$- and $b\bar{b}$-quarkonia are calculated using a symmetry-preserving continuum treatment of the meson bound-state problem which unifies the properties of these heavy-quark systems with those of light-quark bound-states, including QCD's Goldstone modes. Analysing the evolution of ${}^1{S}_0$ and ${}^3{S}_1$ PDAs with current-quark mass, ${\hat{m}}_q$, increasing away from the chiral limit, it is found that in all cases there is a value of ${\hat{m}}_q$ for which the PDA matches the asymptotic form appropriate to QCD's conformal limit and hence is insensitive to changes in renormalisation scale, $\zeta$. This mass lies just above that associated with the $s$-quark. At current-quark masses associated with heavy-quarkonia, on the other hand, the PDAs are piecewise convex-concave-convex. They are much narrower than the asymptotic distribution on a large domain of $\zeta$; but nonetheless deviate noticeably from ${\phi }_{Q\bar{Q}}(x)=\delta (x-1/2)$, which is the result in the static-quark limit. There are also material differences between ${}^1{S}_0$ and ${}^3{S}_1$ PDAs, and between the PDAs for different vector-meson polarisations, which vanish slowly with increasing $\zeta$. An analysis of moments of the root-mean-square relative-velocity, $⟨v^{2m}⟩$, in ${}^1{S}_0$ and ${}^3{S}_1$ systems reveals that $⟨v^4⟩$-contributions may be needed in order to obtain a reliable estimate of matrix elements using such an expansion, especially for processes involving heavy pseudoscalar quarkonia.

    ↳ nucl-thhep-exhep-lathep-ph+1PLB(2016)·77 citations
40. 40*

    On RR Couplings and Bulk Singularity Structures of Non-BPS Branes

    Ehsan Hatefi🇬🇧

    We compute the five point world sheet scattering amplitude of a symmetric closed string Ramond-Ramond , a transverse scalar field, a world volume gauge field and a real tachyon in both world volume and transverse directions of brane in type IIA and IIB superstring theory. We provide the complete analysis of $<C^{-1}{\varphi }^0{A}^0{T}^{-1}>$ S-matrix and show that both $u^{\prime }=u+\frac{1}{4}$ and $t$ channel bulk singularity structures can also be examined by this S-matrix. Various remarks about new restricted Bianchi identities on world volume for the other pictures have also been made.

    ↳ hep-thgr-qchep-phPLB(2016)·13 citations
41. 41*

    Off-Shell CHY Amplitudes

    C.S. Lam🇨🇦 · York-Peng Yao🇺🇸

    The Cachazo-He-Yuan (CHY) formula for on-shell scattering amplitudes are extended off-shell. The off-shell amplitudes are Möbius invariant, and have the same momentum poles as the on-shell amplitudes. The same technique is also used to obtain off-shell massive scalar and vector boson amplitudes.

    ↳ hep-thhep-phNPB(2016)·16 citations
42. 42*

    Extension of the $CPT$ Theorem to non-Hermitian Hamiltonians and Unstable States

    Philip D. Mannheim🇺🇸

    We extend the $CPT$ theorem to quantum field theories with non-Hermitian Hamiltonians and unstable states. Our derivation is a quite minimal one as it requires only the time independent evolution of scalar products, invariance under complex Lorentz transformations, and a non-standard but nonetheless perfectly legitimate interpretation of charge conjugation as an anti-linear operator. The first of these requirements does not force the Hamiltonian to be Hermitian. Rather, it forces its eigenvalues to either be real or to appear in complex conjugate pairs, forces the eigenvectors of such conjugate pairs to be conjugates of each other, and forces the Hamiltonian to admit of an anti-linear symmetry. The latter two requirements then force this anti-linear symmetry to be $CPT$, while forcing the Hamiltonian to be real rather than Hermitian. Our work justifies the use of the $CPT$ theorem in establishing the equality of the lifetimes of unstable particles that are charge conjugates of each other. We show that the Euclidean time path integrals of a $CPT$ symmetric theory must always be real. In the quantum-mechanical limit the key results of the $PT$ symmetry program of Bender and collaborators are recovered, with the $C$-operator of the $PT$ symmetry program being identified with the linear component of the charge conjugation operator.

    ↳ quant-phhep-phhep-thmath-ph+1PLB(2016)·24 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.