Fri·Jan 1, 2016Friday·January 1, 2016

1. 01*

   Phenomenological Implications of an SU(5) x S4 x U(1) SUSY GUT of Flavour

   Maria Dimou🇬🇧 · Stephen F. King🇬🇧 · Christoph Luhn🇩🇪

   We discuss the characteristic low energy phenomenological implications of an SU(5) Supersymmetric Grand Unified Theory (SUSY GUT) whose flavour structure is controlled by the family symmetry S4 x U(1), which provides a good description of all quark and lepton masses, mixings as well as CP violation. Although the model closely mimics Minimal Flavour Violation (MFV) as shown in arXiv:1511.07886, here we focus on the differences. We first present numerical estimates of the low energy mass insertion parameters, including canonical normalisation and renormalisation group running, for well-defined ranges of SUSY parameters and compare the naive model expectations to the numerical scans and the experimental bounds. Our results are then used to estimate the model-specific predictions for Electric Dipole Moments (EDMs), Lepton Flavour Violation (LFV), B and K meson mixing as well as rare B decays. The largest observable deviations from MFV come from the LFV process mu --> e gamma and the electron EDM.

   hep-phPRD(2016)·22 citations
2. 02*

   Decoherence and oscillations of supernova neutrinos

   Joern Kersten🇳🇴 · Alexei Yu. Smirnov🇩🇪

   Supernova neutrinos have several exceptional features which can lead to interesting physical consequences. At the production point their wave packets have an extremely small size ${\sigma }_x\sim 10^{-11}$ cm; hence the energy uncertainty can be as large as the energy itself, ${\sigma }_E\sim E$, and the coherence length is short. On the way to the Earth the wave packets of mass eigenstates spread to macroscopic sizes and separate. Inside the Earth the mass eigenstates split into eigenstates in matter and oscillate again. The coherence length in the Earth is comparable with the radius of the Earth. We explore these features and their consequences. (i) We present new estimates of the wave packet size. (ii) We consider the decoherence condition for the case of wave packets with spatial spread and show that it is not modified by the spread. (iii) We study the coherence of neutrinos propagating in a multi-layer medium with density jumps at the borders of layers. In this case coherence can be partially restored due to a "catch-up effect", increasing the coherence length beyond the usual estimate. This catch-up effect can occur for supernova neutrinos as they cross the shock wave fronts in the exploding star or the core of the Earth.

   hep-phastro-ph.HEEPJC(2016)·57 citations
3. 03*

   Phenomenology of the simple 3-3-1 model with inert scalars

   Phung Van Dong🇻🇳 · N. T. K. Ngan🇻🇳 · T. D. Tham🇻🇳 · L. D. Thien🇻🇳 · N. T. Thuy🇻🇳

   The simple 3-3-1 model that contains the minimal lepton and minimal scalar contents is detailedly studied. The impact of the inert scalars (i.e., the extra fundamental fields that provide realistic dark matter candidates) on the model is discussed. All the interactions of the model are derived, in which the standard model ones are identified. We constrain the standard model like Higgs particle at the LHC. We search for the new particles including the inert ones, which contribute to the $B_s$-${\bar{B}}_s$ mixing, the rare $B_s\to {\mu }^{+}{\mu }^{-}$ decay, the CKM unitarity violation, as well as producing the dilepton, dijet, diboson, diphoton, and monojet final states at the LHC.

   hep-phPRD(2019)·42 citations
4. 04*

   Implications of Gauge Invariance on a Heavy Diphoton Resonance

   Ian Low🇺🇸 · Joseph Lykken🇺🇸

   Assuming a heavy electroweak singlet scalar, which couples to the Standard Model gauge bosons only through loop-induced couplings, SU(2)_L x U(1)_Y gauge invariance imposes interesting patterns on its decays into electroweak gauge bosons, which are dictated by only two free parameters. Therefore experimental measurements on any two of the four possible electroweak channels would determine the remaining two decay channels completely. Furthermore, searches in the WW/ZZ channels probe a complimentary region of parameter space from searches in the gamma-gamma/Z-gamma channels. We derive a model-independent upper bound on the branching fraction in each decay channel, which for the diphoton channel turns out to be about 61%. Including the coupling to gluons, the upper bound on the diphoton branching fraction implies an upper bound on the mass scale of additional colored particles mediating the gluon-fusion production. Using an event rate of about 5 fb for the reported 750 GeV diphoton excess, we find the new colored particle must be lighter than O(1.7 TeV) and O(2.6 TeV) for a pure CP-even and a pure CP-odd singlet scalar, respectively.

   hep-ph69 citations
5. 05*

   A novel and economical explanation for SM fermion masses and mixings

   A. E. Cárcamo Hernández🇨🇱

   I propose the first multiscalar singlet extension of the Standard Model (SM), that generates tree level top quark and exotic fermion masses as well as one and three loop level masses for charged fermions lighter than the top quark and for light active neutrinos, respectively, without invoking electrically charged scalar fields. That model, which is based on the $S_3\times Z_8$ discrete symmetry, successfully explains the observed SM fermion mass and mixing pattern. The charged exotic fermions induce one loop level masses for charged fermions lighter than the top quark. The $Z_8$ charged scalar singlet $\chi$ generates the observed charged fermion mass and quark mixing pattern.

   hep-phEPJC(2016)·117 citations
6. 06*

   Present theoretical uncertainties on charm hadroproduction in QCD and prompt neutrino fluxes

   M.V. Garzelli🇩🇪 · S. Moch🇩🇪 · G. Sigl🇩🇪

   Prompt neutrino fluxes are basic backgrounds in the search of high-energy neutrinos of astrophysical origin, performed by means of full-size neutrino telescopes located at Earth, under ice or under water. Predictions for these fluxes are provided on the basis of up-to-date theoretical results for charm hadroproduction in perturbative QCD, together with a comprehensive discussion of the various sources of theoretical uncertainty affecting their computation, and a quantitative estimate of each uncertainty contribution.

   hep-phEPJ Web Conf.(2016)·0 citations
7. 07*

   Two-photon exchange correction to muon-proton elastic scattering at low momentum transfer

   O. Tomalak🇩🇪 · M. Vanderhaeghen (JGU Mainz)🇩🇪

   We evaluate the two-photon exchange (TPE) correction to the muon-proton elastic scattering at small momentum transfer. Besides the elastic (nucleon) intermediate state contribution, which is calculated exactly, we account for the inelastic intermediate states by expressing the TPE process approximately through the forward doubly virtual Compton scattering. The input in our evaluation is given by the unpolarized proton structure functions and by one subtraction function. For the latter, we provide an explicit evaluation based on a Regge fit of high-energy proton structure function data. It is found that, for the kinematics of the forthcoming muon-proton elastic scattering data of the MUSE experiment, the elastic TPE contribution dominates, and the size of the inelastic TPE contributions is within the anticipated error of the forthcoming data.

   hep-phnucl-exnucl-thEPJC(2016)·48 citations
8. 08*

   Higgs Portal to Inflation and Fermionic Dark Matter

   Aditya Aravind🇺🇸 · Minglei Xiao🇺🇸 · Jiang-Hao Yu🇺🇸

   We investigate an inflationary model involving a gauge singlet scalar and fermionic dark matter. The mixing between the singlet scalar and the Higgs boson provides a portal to dark matter. The inflaton could either be the Higgs boson or the singlet scalar, and slow roll inflation is realized via its non-minimal coupling to gravity. In this setup, the effective scalar potential is stabilized by the mixing between two scalars and coupling with dark matter. We study constraints from collider searches, relic density and direct detection, and find that dark matter mass should be around half the mass of either the Higgs boson or singlet scalar. Using the renormalization group equation improved scalar potential and putting all the constraints together, we show that the inflationary observables $n_s-r$ are consistent with current Planck data.

   hep-phgr-qchep-thPRD(2016)·33 citations
9. 09*

   750 GeV Resonance in the Gauged $U(1{)}^{\prime }$-Extended MSSM

   Yun Jiang🇩🇰 · Ying-Ying Li🇨🇳 · Tao Liu🇨🇳

   Recently the ATLAS and CMS collaborations at the LHC announced their observation of a potential 750 GeV di-photon resonance, after analyzing the $\sqrt{s}=13$ TeV LHC data. This observation has significant implications for low-energy supersymmetry. Beyond the MSSM and the NMSSM, we study the MSSM-extensions with an extra $U(1{)}^{\prime }$ gauge symmetry. The anomaly cancellation and the spontaneous breaking of the non-decoupled $U(1{)}^{\prime }$ generically require introducing vector-like supermultiplets (both colored and color-neutral ones) and singlet supermultiplets, respectively. We illustrate that the potential 750 GeV resonance ($Y$) can be accommodated in various mechanisms, as a singlet-like scalar or pseudoscalar. Three benchmark scenarios are presented: (1) vector-like quarks (VLQ) mediated $pp\to Y\to \gamma \gamma$; (2) scalar VLQ mediated $pp\to Y\to \gamma \gamma$; (3) heavy scalar (pseudo-scalar) $H/A$ associated production $pp\to H^{\ast }/A^{\ast }\to YH/h$. Additionally, we notice that the $Z^{\prime }$-mediated vector boson fusion production and $Z^{\prime }$-associated production $pp\to Yq{q}^{\prime }$, if yielding a signal rate of the observed level, might have been excluded by the searches for $Z^{\prime }$ via Drell-Yan process at the LHC.

   hep-phPLB(2016)·69 citations
10. 10*

    Diphoton channel at the LHC experiments to find a hint for a new heavy gauge boson

    Kunio Kaneta🇰🇷 · Subeom Kang🇰🇷 · Hye-Sung Lee🇰🇷

    Recently there has been a huge interest in the diphoton excess around 750 GeV reported by both ATLAS and CMS collaborations, although the newest analysis with more statistics does not seem to support the excess. Nevertheless, the diphoton channel at the LHC experiments are a powerful tool to probe a new physics. One of the most natural explanations of a diphoton excess, if it occurs, could be a new scalar boson with exotic colored particles. In this setup, it would be legitimate to ask what is the role of this new scalar in nature. A heavy neutral gauge boson ($Z^{\prime }$) is one of the traditional targets of the discovery at the collider experiments with numerous motivations. While the Landau-Yang theorem dictates the diphoton excess cannot be this spin-1 gauge boson, there is a strong correlation of a new heavy gauge boson and a new scalar boson which provides a mass to the gauge boson being at the same mass scale. In this paper, we point out a simple fact that a new scalar with a property similar to the recently highlighted 750 GeV would suggest an existence of a TeV scale $Z^{\prime }$ gauge boson that might be within the reach of the LHC Run 2 experiments. We take a scenario of the well-motivated and popular gauged $B-L$ symmetry and require the gauge coupling unification to predict the mass and other properties of the $Z^{\prime }$ and illustrate the discovery of the $Z^{\prime }$ would occur during the LHC experiments.

    hep-phInt.J.Mod.Phys.A(2016)·69 citations
11. 11*

    Exclusive Radiative Z-Boson Decays to Mesons with Flavor-Singlet Components

    Stefan Alte (JGU Mainz)🇩🇪 · Matthias Koenig (JGU Mainz)🇩🇪 · Matthias Neubert (MITP Mainz and Cornell Univ.)🇩🇪

    We present a detailed study of the exclusive radiative decays $Z\to {\eta }^{(\prime )}\gamma$ employing the QCD factorization approach. We derive a factorization formula for the decay amplitudes valid at leading power in an expansion in $({\Lambda }_{QCD}/m_Z{)}^2$, which includes convolutions of calculable hard-scattering kernels with the leading-twist quark and gluon light-cone distribution amplitudes of the mesons. Large logarithms arising in the evolution from the high scale $m_Z$ down to hadronic scales are resummed using the renormalization group, carefully accounting for the effects of the heavy bottom and charm quarks. Our results for the branching ratios are very sensitive to hadronic input parameters, such as the decay constants and mixing angle characterizing the $\eta -{\eta }^{\prime }$ system. Using the most recent estimates of these parameters, we obtain the branching ratios $Br(Z\to \eta \gamma )\sim 1.6\cdot 10^{-10}$ and $Br(Z\to {\eta }^{\prime }\gamma )\sim 4.7\cdot 10^{-9}$. A measurement of these processes at a future high-luminosity Z factory could provide interesting information on the gluon distribution amplitude.

    hep-phJHEP(2016)·20 citations
12. 12*

    Non-minimal CW inflation, electroweak symmetry breaking and the 750 GeV anomaly

    Luca Marzola🇪🇪 · Antonio Racioppi🇪🇪 · Martti Raidal🇪🇪 · Federico R. Urban🇪🇪 · Hardi Veermäe🇪🇪

    We study whether the hinted 750 GeV resonance at the LHC can be a Coleman-Weinberg inflaton which is non-minimally coupled to gravity. Since the inflaton must couple to new charged and coloured states to reproduce the LHC diphoton signature, the same interaction can generate its effective potential and trigger the electroweak symmetry breaking via the portal coupling to the Higgs boson. This inflationary scenario predicts a lower bound on the tensor-to-scalar ratio of $r\gtrsim 0.006$, where the minimal value corresponds to the measured spectral index $n_s\simeq 0.97$. However, we find that the compatibility with the LHC diphoton signal requires exotic new physics at energy scales accessible at the LHC. We study and quantify the properties of the predicted exotic particles.

    hep-phastro-ph.COgr-qchep-thJHEP(2016)·90 citations
13. 13*

    Testing LHT at the LHC Run-II

    Qing-Hong Cao · Chuan-Ren Chen · Yandong Liu

    We study the Littlest Higgs model with T-parity (LHT) in the process of $pp\to W_H^{+}{W}_H^{-}\to W^{+}{W}^{-}{A}_H{A}_H$ at the 14 TeV LHC. With the $W$-jet tagging technique, we demonstrate that the bulk of the model parameter space can be probed at the level of more than $5\sigma$ in the signature of two fat $W$-jets plus large missing energy. Furthermore, we propose a novel strategy of measuring the principle parameter $f$ that is crucial to testify the LHT model and to fix mass spectrum, including dark matter particle. Our proposal can be easily incorporated into current experimental program of diboson searches at the LHC Run-II.

    hep-phhep-exPRD(2016)·3 citations
14. 14*

    Lepton Flavor Violating Non-Standard Interactions via Light Mediators

    Yasaman Farzan🇮🇷 · Ian M. Shoemaker🇺🇸

    Non-Standard neutral current Interactions (NSIs) of neutrinos with matter can alter the pattern of neutrino oscillation due to the coherent forward scattering of neutrinos on the medium. This effect makes long-baseline neutrino experiments such as NO$\nu$A and DUNE a sensitive probe of beyond standard model (BSM) physics. We construct light mediator models that can give rise to both lepton flavor conserving as well as Lepton Flavor Violating (LFV) neutral current NSI. We outline the present phenomenological viability of these models and future prospects to test them. We predict a lower bound on Br$(H\to \mu \tau )$ in terms of the parameters that can be measured by DUNE and NO$\nu$A, and show that the hint for $H\to \mu \tau$ in current LHC data can be accommodated in our model. A large part of the parameter space of the model is already constrained by the bounds on Br$(\tau \to Z^{\prime }\mu )$ and rare meson decays and can in principle fully tested by improving these bounds.

    hep-phJHEP(2016)·144 citations
15. 15*

    MSSM from F-theory SU(5) with Klein Monodromy

    Miguel Crispim Romão🇬🇧 · Athanasios Karozas🇬🇷 · Stephen F. King🇬🇧 · George K. Leontaris🇬🇷 · Andrew K. Meadowcroft🇬🇧

    We revisit a class of $SU(5)$ SUSY GUT models which arise in the context of the spectral cover with Klein Group monodromy $V_4=Z_2\times Z_2$. We show that $Z_2$ matter parities can be realised via new geometric symmetries respected by the spectral cover. We discuss a particular example of this kind, where the low energy effective theory below the GUT scale is just the MSSM with no exotics and standard matter parity, extended by the seesaw mechanism with two right-handed neutrinos.

    hep-phPRD(2016)·12 citations
16. 16*

    Diphoton Revelation of the Utilitarian Supersymmetric Standard Model

    Ernest Ma (UC Riverside and HKUST/JCIAS)🇺🇸

    In 2002, I proposed a unique $U(1)$ extension of the supersymmetric standard model which has no $\mu$ term and conserves baryon number and lepton number separately and automatically. This model, $withoutanychange$, has all the necessary and sufficient ingredients to explain the possible 750 GeV diphoton excess, observed recently by the ATLAS Collaboration at the Large Hadron Collider (LHC). It is associated with the superfield which replaces the $\mu$ parameter. If confirmed and supported by subsequent data, it may even be considered as the first evidence for supersymmetry.

    hep-ph40 citations
17. 17*

    Light Stop Mass Limits from Higgs Rate Measurements in the MSSM: Is MSSM Electroweak Baryogenesis Still Alive After All?

    Stefan Liebler🇩🇪 · Stefano Profumo🇺🇸 · Tim Stefaniak🇺🇸

    We investigate the implications of the Higgs rate measurements from Run 1 of the LHC for the mass of the light scalar top partner (stop) in the Minimal Supersymmetric Standard Model (MSSM). We focus on light stop masses, and we decouple the second, heavy stop and the gluino to the multi-TeV range in order to obtain a Higgs mass of around 125 GeV. We derive lower mass limits for the light stop within various scenarios, taking into account the effects of a possibly light scalar tau partner (stau) or chargino on the Higgs rates, of additional Higgs decays to undetectable new physics, as well as of non-decoupling of the heavy Higgs sector. Under conservative assumptions, the stop can be as light as 123 GeV. Relaxing certain theoretical and experimental constraints, such as vacuum stability and model-dependent bounds on sparticle masses from LEP, we find that the light stop mass can be as light as 116 GeV. Our indirect limits are complementary to direct limits on the light stop mass from collider searches and have important implications for electroweak baryogenesis in the MSSM as a possible explanation for the observed matter-antimatter asymmetry of the Universe.

    hep-phhep-exJHEP(2016)·36 citations
18. 18*

    Minimal Left-Right Symmetry Confronted with the 750 GeV Di-photon Excess at LHC

    Arnab Dasgupta🇮🇳 · Manimala Mitra🇮🇳 · Debasish Borah🇮🇳

    The recent results of 13 TeV ATLAS and CMS di-photon searches show an excess at di-photon invariant mass of 750 GeV. We look for possible explanation of this within minimal left right symmetric model (MLRSM). The possible candidate is a neutral Higgs of mass 750 GeV that can decay to di-photon via charged Higgs and right handed gauge boson loop. However, the cross-section is not consistent with the ATLAS and CMS results. We then discuss one possible variation of this model with universal seesaw for fermion masses that can explain this excess.

    hep-ph74 citations
19. 19*

    Charmed hadron photoproduction at COMPASS

    Xiao-Yun Wang🇨🇳 · Alexey Guskov🇷🇺

    Photoproduction of the charmonium-like state $Z_c(4200)$ and the charmed baryon ${\Lambda }_c^{\ast }(2940)$ is investigated with an effective Lagrangian approach and the Regge trajectories applying to the COMPASS experiment. Combining the experimental data from COMPASS and our theoretical model we estimate the upper limit of ${\Gamma }_{Z_c(4200)\to J/\psi \pi }$ to be of about 37 MeV. Moreover, the possibility to produce ${\Lambda }_c^{\ast }(2940)$ at COMPASS is discussed. It seems one can try to search for this hadron in the missing mass spectrum since the $t$-channel is dominating for the ${\Lambda }_c^{\ast }(2940)$ photoproduction.

    hep-phOpen Phys.(2016)·0 citations
20. 20*

    Constraints on Gravitino Decay and the Scale of Inflation using CMB spectral distortions

    Emanuela Dimastrogiovanni🇺🇸 · Lawrence M. Krauss🇺🇸 · Jens Chluba🇬🇧

    If local supersymmetry is the correct extension of the standard model of particle physics, then following Inflation the early universe would have been populated by gravitinos produced from scatterings in the hot plasma during reheating. Their abundance is directly related to the magnitude of the reheating temperature. The gravitino lifetime is fixed as a function of its mass, and for gravitinos with lifetimes longer than the age of the universe at redshift $z\simeq 2\times 10^6$ (or roughly $6\times 10^6\mathrm{s}$), decay products can produce spectral distortion of the cosmic microwave background. Currently available COBE/FIRAS limits on spectral distortion can, in certain cases, already be competitive with respect to cosmological constraints from primordial nucleosynthesis for some gravitino decay scenarios. We show how the sensitivity limits on $\mu$ and $y$ distortions that can be reached with current technology would improve constraints and possibly rule out a significant portion of the parameter space for gravitino masses and Inflation reheating temperatures.

    hep-phastro-ph.COPRD(2016)·25 citations
21. 21*

    A global $SU(3)/U(3)$ flavor symmetry analysis for $B\to PP$ with $\eta -{\eta }^{\prime }$ Mixing

    Yu-Kuo Hsiao🇨🇳 · Chia-Feng Chang🇹🇼 · Xiao-Gang He🇹🇼

    A large number of new experimental data on $B$ decay into two light pesudoscalar ($P$) mesons have been collected by the LHCb collaboration. Besides confirming information on $B_{u,d}\to PP$ decays obtained earlier by B-factories at KEK and SLAC, new information on $B_s\to PP$ and also more decay modes with $P$ being $\eta$ or ${\eta }^{\prime }$ have been obtained. Using these new data, we perform a global fit for $B\to PP$ to determine decay amplitudes in the framework of $SU(3)/U(3)$ flavor symmetry. We find that $SU(3)$ flavor symmetry can explain data well. The annihilation amplitudes are found to be small as expected. Several CP violating relations predicted by $SU(3)$ flavor symmetry are in good agreement with data. Current available data can give constraints on the amplitudes which induce $P=\eta ,{\eta }^{\prime }$ decays in the framework of $U(3)$ flavor symmetry, and can also determine the $\eta -{\eta }^{\prime }$ mixing angle $\theta$ with $\theta =(-18.4\pm 1.2{)}^{\circ }$. Several $B\to PP$ decay modes which have not been measured are predicted with branching ratios accessible at the LHCb. These decays can provide further tests for the framework of $SU(3)/U(3)$ flavor symmetry for $B$ decays.

    hep-phhep-exPRD(2016)·62 citations
22. 22*

    Non-standard charged Higgs decay at the LHC in Next-to-Minimal Supersymmetric Standard Model

    Priyotosh Bandyopadhyay🇮🇹 · Katri Huitu🇫🇮 · Saurabh Niyogi🇮🇳

    We consider next-to-minimal supersymmetric standard model (NMSSM) which has a gauge singlet superfield. In the scale invariant superpotential we do not have the mass terms and the whole Lagrangian has an additional $Z_3$ symmetry. This model can have light scalar and/or pseudoscalar allowed by the recent data from LHC and the old data from LEP. We investigate the situation where a relatively light charged Higgs can decay to such singlet-like pseudoscalar and a $W^{\pm }$ boson giving rise to final state containing $\tau$ and/or $b$-jets and lepton(s). Such decay evades the recent bounds on charged Higgs from the LHC. According to our PYTHIA-FastJet based simulation such a scenario can be probed with early data of 10 fb${}^{-1}$ at the LHC center of mass energy of 13 and 14 TeV.

    hep-phJHEP(2016)·18 citations
23. 23*

    Sub-jet structure as a discriminating quenching probe

    Xiaoming Zhang🇺🇸 · Liliana Apolinário🇵🇹 · José Guilherme Milhano🇵🇹 · Mateusz Płoskoń🇺🇸

    In this work, we propose a new class of jet substructure observables which, unlike fragmentation functions, are largely insensitive to the poorly known physics of hadronization. We show that sub-jet structures provide us with a large discriminating power between different jet quenching Monte Carlo implementations.

    hep-phNPA(2016)·7 citations
24. 24*

    R^2 corrections to the jet quenching parameter

    Zi-qiang Zhang🇨🇳 · De-fu Hou🇨🇳 · Yan Wu🇨🇳 · Gang Chen🇨🇳

    A calculation of the $R^2$ corrections to the jet quenching parameter from AdS/CFT correspondence is presented. These corrections are related to curvature-squared corrections in the corresponding gravity dual. It is shown that the corrections will increase or decrease the jet quenching parameter depending on the coefficients of the high curvature terms.

    hep-phAdv.High Energy Phys.(2016)·7 citations
25. 25*

    Centrality dependence of forward $J/\psi$ suppression in high energy proton-nucleus collisions

    B. Ducloué🇫🇮 · T. Lappi🇫🇮 · H. Mäntysaari🇺🇸

    The production of forward $J/\psi$ mesons in proton-nucleus collisions can provide important information on gluon saturation. In a previous work we studied this process in the Color Glass Condensate framework, describing the target using a dipole cross section fitted to HERA inclusive data and extrapolated to the case of a nuclear target using the optical Glauber model. In this work we study the centrality dependence of the nuclear suppression in this model and compare our results with recent LHC data for this observable.

    hep-phnucl-thNPA(2016)·0 citations
26. 26*

    A CP-conserving multi-Higgs model without real basis

    I. P. Ivanov🇵🇹 · Joao P. Silva🇵🇹

    Models beyond the Standard Model (bSM) often involve elaborate Higgs sectors, which can be a source of CP-violation. It brings up the question of recognizing in an efficient way whether a model is CP-violating. There is a diffuse belief that the issue of explicit CP invariance can be linked to the existence of a basis in which all coefficients are real; with even a theorem proposed a decade ago claiming that the scalar sector of any multi-Higgs doublet model is explicitly CP-conserving if and only if all of its coefficients can be made real by a basis change. This is compounded by the fact that in all specific multi Higgs models considered so far, the calculations complied with this claim. Here, we present the first counterexample to this statement: a CP-conserving three-Higgs-doublet model for which no real basis exists. We outline the phenomenological consequences of this model, and notice that the extra neutral Higgs bosons are neither CP-even nor CP-odd but are "half-odd" under the generalized CP-symmetry of the model.

    hep-phPRD(2016)·72 citations
27. 27*

    Unified description of quarks and leptons in a multi-spinor field formalism

    Ikuo S. Sogami (Department of Physics, Kyoto Sangyo University and Yukawa Institute of Theoretical Physics, Kyoto University)🇯🇵

    Multi-spinor fields which behave as triple-tensor products of the Dirac spinors and form reducible representations of the Lorentz group describe three families of ordinary quarks and leptons in the visible sector and an additional family of exotic dark quarks and leptons in the dark sector of the Universe. Apart from the ordinary set of the gauge and Higgs fields in the visible sector, another set of gauge and Higgs fields belonging to the dark sector are assumed to exist. Two sectors possess channels of communication through gravity and a bi-quadratic interaction between the two types of Higgs fields. A candidate for the main component of the dark matter is a stable dark hadron with spin 3/2, and the upper limit of its mass is estimated to be 15.1 GeV/c${}^2$.

    hep-phBled Workshops Phys.(2015)·5 citations
28. 28*

    Final state interaction on $B^{+}\to {\pi }^{-}{\pi }^{+}{\pi }^{+}$

    I. Bediaga🇧🇷 · P. C. Magalhães🇧🇷

    The large localized CP asymmetries observed by LHCb in three-body charmless decays of $B$ mesons brings new challenge for experimentalists and their traditional models to fit data. With higher statistics, rescattering and three-body effects, previously ignored on data analysis, become more visible. The time is ripe to use better theoretical assumptions as an ingredient in order to improve the analysis. In this paper we address the issue of rescattering effects in the charmless three-body decays of $B$ mesons. In particular, we study the case of the $B^{+}\to {\pi }^{-}{\pi }^{+}{\pi }^{+}$ decay and show that the presence of hadronic loops shifts the P-wave phase near threshold to below zero, and modify the position of the $\rho$-meson peak and it width, in the Dalitz plot.

    hep-phhep-ex47 citations
29. 29*

    $\eta$ and ${\eta }^{\prime }$ decays into lepton pairs

    Pere Masjuan🇩🇪 · Pablo Sanchez-Puertas🇩🇪

    In this work, we calculate the branching ratios for the $\eta ({\eta }^{\prime })\to \bar{\ell }\ell$ decays, where $\ell =e,\mu$. These processes have tiny rates in the standard model due to spin flip, loop, and electromagnetic suppression, for what they could be sensitive to New Physics effects. In order to provide a reliable input for the Standard Model, we exploit the general analytical properties of the amplitude. For that purpose, we invoke the machinery of Canterbury approximants, which provides a systematic description of the underlying hadronic physics in a data-driven fashion. Given the current experimental discrepancies, we discuss in detail the role of the resonant region and comment on the reliability of $\chi$PT calculations. Finally, we discuss the kind of new physics which we think would be relevant to account for them.

    hep-phhep-exnucl-thJHEP(2016)·59 citations
30. 30*

    Left-right non-linear dynamical Higgs

    Jing Shu🇨🇳 · Juan Yepes🇨🇳

    All the possible CP-conserving non-linear operators up to the $p^4$-order in the Lagrangian expansion are analysed here for the left-right symmetric model in the non-linear electroweak chiral context coupled to a light dynamical Higgs. The low energy effects will be triggered by an emerging new physics field content in the nature, more specifically, from spin-1 resonances sourced by the straightforward extension of the SM local gauge symmetry to the larger local group $SU(2{)}_L\otimes SU(2{)}_R\otimes U(1{)}_{B-L}$. Low energy phenomenology will be altered by integrating out the resonances from the physical spectrum, being manifested through induced corrections onto the left handed operators. Such modifications are weighted by powers of the scales ratio implied by the symmetries of the model and will determine the size of the effective operator basis to be used. The recently observed diboson excess around the invariant mass 1.8-2 TeV entails a scale suppression that suggests to encode the low energy effects via a much smaller set of effective operators.

    hep-phCommun.Theor.Phys.(2016)·10 citations
31. 31*

    Charm hadrons above $T_c$

    Swagato Mukherjee🇺🇸 · P. Petreczky🇺🇸 · S. Sharma🇺🇸

    From the analysis of the lattice data on fluctuations and correlations of charm we conclude that open charm meson and baryon-like excitations exist above the QCD crossover temperature, and in fact are the dominant degrees of freedom for thermodynamics in the vicinity of the transition. Charm quarks become the dominant charm degrees of freedom only for temperatures T>200 MeV.

    hep-phhep-latnucl-thNPA(2016)·0 citations
32. 32*

    Distinguishing between $\Lambda$CDM and modified gravity with future observations of cosmic growth rate

    Koichi Hirano🇯🇵

    A probability of distinguishing between $\Lambda$CDM model and modified gravity is studied by using the future observations for the growth rate of cosmic structure (Euclid redshift survey). Adopting extended DGP model, Kinetic Gravity Braiding model, and Galileon model as modified gravity, we compare predicted cosmic growth rate by models to the mock observational data. The growth rate $f{\sigma }_8$ in the original DGP model is suppressed compared with the $\Lambda$CDM case, for the same value of the current density parameter of matter ${\Omega }_{m,0}$, because of the suppression of effective gravitational constant. In case of the kinetic gravity braiding model and the Galileon model, the growth rate $f{\sigma }_8$ is enhanced compared with the $\Lambda$CDM case, for the same value of ${\Omega }_{m,0}$, because of the enhancement of effective gravitational constant. For future observational data of the cosmic growth rate (Euclid), compatible value of ${\Omega }_{m,0}$ are different by models, furthermore ${\Omega }_{m,0}$ can be stringently constrained. Thus, we find the $\Lambda$CDM model is distinguishable from modified gravity by combining the growth rate data of the Euclid with other observations.

    ↳ astro-ph.COgr-qchep-phhep-th2 citations
33. 33*

    Thermal relics as hot, warm and cold dark matter in power-law $f(R)$ gravity

    David Wenjie Tian🇨🇦

    We investigate the thermal relics as hot, warm and cold dark matter in $\mathcal{L}={\epsilon }^{2-2\beta }{R}^{\beta }+16\pi m_{\text{Pl}}^{-2}{\mathcal{L}}_m$ gravity, where $\epsilon$ is a constant balancing the dimension of the field equation, and $1<\beta <(4+\sqrt{6})/5$ for the positivity of energy density and temperature. If light neutrinos serve as hot/warm relics, the entropic number of statistical degrees of freedom $g_{\ast s}$ at freeze-out and thus the predicted fractional energy density ${\Omega }_{\psi }{h}^2$ are $\beta -$dependent, which relaxes the standard mass bound $\Sigma m_{\nu }$. For cold relics, by exactly solve the simplified Boltzmann equation in both relativistic and nonrelativistic regimes, we show that the Lee-Weinberg bound for the mass of heavy neutrinos can be considerably relaxed, and the 'WIMP miracle" for weakly interacting massive particles (WIMPs) gradually invalidates as $\beta$ deviates from $\beta =1^{+}$. The whole framework reduces to become that of GR in the limit $\beta \to 1^{+}$.

    ↳ astro-ph.COgr-qchep-ph0 citations
34. 34*

    Supersymmetric k-defects

    Michael Koehn🇺🇸 · Mark Trodden🇺🇸

    In supersymmetric theories, topological defects can have nontrivial behaviors determined purely by whether or not supersymmetry is restored in the defect core. A well-known example of this is that some supersymmetric cosmic strings are automatically superconducting, leading to important cosmological effects and constraints. We investigate the impact of nontrivial kinetic interactions, present in a number of particle physics models of interest in cosmology, on the relationship between supersymmetry and supercurrents on strings. We find that in some cases it is possible for superconductivity to be disrupted by the extra interactions.

    ↳ hep-thastro-ph.COhep-phPLB(2016)·11 citations
35. 35*

    High temperature Bose-Einstein condensation

    Viktor V. Begun🇵🇱

    The indications of a possible pion condensation at the LHC are summarized. The condensation is predicted by the non-equilibrium hadronization model for 2.76 TeV Pb+Pb collisions at the LHC. The model solves the proton/pion puzzle and reproduces the low $p_T$ enhancement of the pion spectra, as well as the spectra of protons and antiprotons, charged kaons, $K_S^0$, $K^{\ast }(892{)}^0$ and $\varphi (1020)$. The obtained parameters allow to estimate the amount of pion condensate on the level of 5\% from the total number of pions at the LHC. The condensate is located at $p_T<250$ MeV.

    ↳ nucl-thhep-phEPJ Web Conf.(2016)·4 citations
36. 36*

    Quantum field theory with a preferred direction: The very special relativity framework

    Cheng-Yang Lee🇧🇷

    The theory of very special relativity (VSR) proposed by Cohen and Glashow contains an intrinsic preferred direction. Starting from the irreducible unitary representation of the inhomogeneous VSR group $ISIM(2)$, we present a rigorous construction of quantum field theory with a preferred direction. We find, although the particles and their quantum fields between the VSR and Lorentz sectors are physically different, they share many similarities. The massive spin-half and spin-one vector fields are local and satisfy the Dirac and Proca equations respectively. This result can be generalised to higher-spin field theories. By studying the Yukawa and standard gauge interactions, we obtain a qualitative understanding on the effects of the preferred direction. Its effect is manifest for polarised processes but are otherwise absent.

    ↳ hep-thhep-phPRD(2016)·19 citations
37. 37*

    Chiral symmetry restoration in static-light mesons: chiral restoration theorem, the quark running mass m(k) and first chiral restoration signals in the lattice QCD spectra

    P. Bicudo🇵🇹

    Chiral symmetry restoration high in the hadron spectra is expected but it remains to be confirmed both in lattice QCD computations and in experiments. Recently, a theorem was derived, relating chiral symmetry restoration high in the hadron spectra to the spontaneous generation of the dynamical quark mass in QCD. We refine the theorem in the case of static-light mesons. Utilizing chiral quark model computations and lattice QCD results for the spectrum of mesons composed by a static antiquark and a light quark, we explore chiral symmetry restoration in the spectrum and the quark running mass m(k).

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

    Periods and Feynman amplitudes

    Francis Brown

    Feynman amplitudes in perturbation theory form the basis for most predictions in particle collider experiments. The mathematical quantities which occur as amplitudes include values of the Riemann zeta function and relate to fundamental objects in number theory and algebraic geometry. This talk reviews some of the recent developments in this field, and explains how new ideas from algebraic geometry have led to much progress in our understanding of amplitudes. In particular, the idea that certain transcendental numbers, such as $\pi$, can be viewed as a representation of a group, provides a powerful framework to study amplitudes which reveals many hidden structures.

    ↳ math-phhep-phmath.MP15 citations
39. 39*

    A viable logarithmic f(R) model for inflation

    M. Amin🇪🇬 · S. Khalil🇪🇬 · M. Salah🇪🇬

    Inflation in the framework of $f(R)$ modified gravity is revisited. We study the conditions that $f(R)$ should satisfy in order to lead to a viable inflationary model in the original form and in the Einstein frame. Based on these criteria we propose a new logarithmic model as a potential candidate for $f(R)$ theories aiming to describe inflation consistent with observations from \textit{Planck} satellite (2015). The model predicts scalar spectral index $0.9615<n_s<0.9693$ in agreement with observation and tensor-to-scalar ratio $r$ of order $10^{-3}$. Furthermore, we show that for a class of models, a natural coupling between inflation and a scalar boson is generated through the minimal coupling between gravity and matter fields and a reheating temperature less that $10^9$ GeV is obtained.

    ↳ hep-thgr-qchep-phJCAP(2016)·23 citations
40. 40*

    Anomalous dimensions on the lattice

    Joel Giedt🇺🇸

    We review methods and results for extracting the anomalous dimensions of operators from lattice field theory calculations. The most important application is the anomalous mass dimension in conformal or nearly conformal gauge field theories which might be related to dynamical electroweak symmetry breaking. Some discussion of the underlying theory of renormalization and mixing of operators is also included.

    ↳ hep-lathep-phInt.J.Mod.Phys.A(2016)·17 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.