Thu·Nov 17, 2016Thursday·November 17, 2016

1. 01*

   The seesaw path to leptonic CP violation

   A. Caputo🇪🇸 · P. Hernandez🇪🇸 · M. Kekic🇪🇸 · J. Lopez-Pavon🇨🇭 · J. Salvado🇪🇸

   Future experiments such as SHiP and high-intensity $e^{+}{e}^{-}$ colliders will have a superb sensitivity to heavy Majorana neutrinos with masses below $M_Z$. We show that the measurement of the mixing to electrons and muons of one such state could imply the discovery of leptonic CP violation in the context of seesaw models. We quantify in the minimal model the CP discovery potential of these future experiments, and demonstrate that a 5$\sigma$ CL discovery of leptonic CP violation would be possible in a very significant fraction of parameter space.

   hep-phEPJC(2017)·53 citations
2. 02*

   Imposing LHC constraints on the combined Anomaly and $Z^{\prime }$ Mediation Mechanism of Supersymmetry Breaking

   Joydeep Roy🇺🇸

   Combining anomaly with $Z^{\prime }$ mediation allows us to solve the tachyonic problem of the former and avoid fine tuning in the latter. This model includes an extra $U(1{)}^{\prime }$ gauge symmetry and extra singlet scalar $S$ which provides a solution to the `$\mu$ problem' of the Minimal Supersymmetric Standard Model (MSSM). The low-energy particle spectrum is calculated from the UV inputs using the Renormalization Group Equations. The benchmark points considered in the original model, suggested before the Higgs discovery, predicted a Higgs mass heavier than the generic MSSM value. In 2012, the Higgs particle was discovered and found to have a mass of 125 GeV. Therefore, we can use that value and other current LHC data to scan the parameter space and update the predictions of the model, in particular the mass of the $Z^{\prime }$ gauge boson.

   hep-phPoS(2016)·0 citations
3. 03*

   Generalized Gauge U(1) Family Symmetry for Quarks and Leptons

   Corey Kownacki🇺🇸 · Ernest Ma🇺🇸 · Nicholas Pollard🇺🇸 · Mohammadreza Zakeri🇺🇸

   If the standard model of quarks and leptons is extended to include three singlet right-handed neutrinos, then the resulting fermion structure admits an infinite number of anomaly-free solutions with just one simple constraint. Well-known examples satisfying this constraint are $B-L$, $L_{\mu }-L_{\tau }$ , $B-3L_{\tau }$ , etc. We derive this simple constraint, and discuss two new examples which offer some insights to the structure of mixing among quark and lepton families, together with their possible verification at the Large Hadron Collider.

   hep-phPLB(2017)·30 citations
4. 04*

   Gravitino or Axino Dark Matter with Reheat Temperature as high as $10^{16}$ GeV

   Raymond T. Co🇺🇸 · Francesco D'Eramo🇺🇸 · Lawrence J. Hall🇺🇸

   A new scheme for lightest supersymmetric particle (LSP) dark matter is introduced and studied in theories of TeV supersymmetry with a QCD axion, $a$, and a high reheat temperature after inflation, $T_R$. A large overproduction of axinos ($\tilde{a}$) and gravitinos ($\tilde{G}$) from scattering at $T_R$, and from freeze-in at the TeV scale, is diluted by the late decay of a saxion condensate that arises from inflation. The two lightest superpartners are $\tilde{a}$, with mass of order the TeV scale, and $\tilde{G}$ with mass $m_{3/2}$ anywhere between the keV and TeV scales, depending on the mediation scale of supersymmetry breaking. Dark matter contains both warm and cold components: for $\tilde{G}$ LSP the warm component arises from $\tilde{a}\to \tilde{G}a$, while for $\tilde{a}$ LSP the warm component arises from $\tilde{G}\to \tilde{a}a$. The free-streaming scale for the warm component is predicted to be of order 1 Mpc (and independent of $m_{3/2}$ in the case of $\tilde{G}$ LSP). $T_R$ can be as high as $10^{16}$ GeV, for any value of $m_{3/2}$, solving the gravitino problem. The PQ symmetry breaking scale $V_{PQ}$ depends on $T_R$ and $m_{3/2}$ and can be anywhere in the range $(10^{10}-10^{16})$ GeV. Detailed predictions are made for the lifetime of the neutralino LOSP decaying to $\tilde{a}+h/Z$ and $\tilde{G}+h/Z/\gamma$, which is in the range of $(10^{-1}-10^6)$m over much of parameter space. For an axion misalignment angle of order unity, the axion contribution to dark matter is sub-dominant, except when $V_{PQ}$ approaches $10^{16}$ GeV.

   hep-phJHEP(2017)·43 citations
5. 05*

   Four Tops for LHC

   Ezequiel Alvarez🇦🇷 · Darius A. Faroughy🇸🇮 · Jernej F. Kamenik🇸🇮 · Roberto Morales🇦🇷 · Alejandro Szynkman🇦🇷

   We design a search strategy for the Standard Model $t\bar{t}t\bar{t}$ production at the LHC in the same-sign dilepton and trilepton channels. We study different signal features and, given the small expected number of signal events, we scrutinize in detail all reducible and irreducible backgrounds. Our analysis shows that by imposing a set of basic jet and lepton selection criteria, the SM $pp\to t\bar{t}t\bar{t}$ process could be evidenced in the near future, within Run-II, when combining both multi-lepton search channels. We argue that this search strategy should also be used as a guideline to test New Physics coupling predominantly to top-quarks. In particular, we show that a non-resonant New Physics enhancement in the four-top final state would be detectable through this search strategy. We study two {\it top-philic} simplified models of this kind, a neutral scalar boson and a $Z^{\prime }$, and present current and future exclusion limits on their mass and couplings.

   hep-phhep-exNPB(2017)·74 citations
6. 06*

   Beyond WIMPs: the Quark (Anti) Nugget Dark Matter

   Ariel Zhitnitsky🇨🇦

   We review a testable dark matter (DM) model outside of the standard WIMP paradigm. The model is unique in a sense that the observed ratio ${\Omega }_{\mathrm{dark}}\simeq {\Omega }_{\mathrm{visible}}$ for visible and dark matter densities finds its natural explanation as a result of their common QCD origin when both types of matter (DM and visible) are formed during the QCD transition and both are proportional to single dimensional parameter of the system, ${\Lambda }_{\mathrm{QCD}}$. We argue that the charge separation effect also inevitably occurs during the same QCD transition in the presence of the $\mathcal{C}\mathcal{P}$ odd axion field $a(x)$. It leads to preferential formation of one species of nuggets on the scales of the visible Universe where the axion field $a(x)$ is coherent. A natural outcome of this preferential evolution is that only one type of the visible baryons (not anti- baryons) remain in the system after the nuggets complete their formation. Unlike conventional WIMP dark matter candidates, the nuggets and anti-nuggets are strongly interacting but macroscopically large objects. The rare events of annihilation of the anti-nuggets with visible matter lead to a number of observable effects. We argue that the relative intensities for a number of measured excesses of emission from the centre of galaxy (covering more than 11 orders of magnitude) are determined by standard and well established physics. At the same time the absolute intensity of emission is determined by a single new fundamental parameter of the theory, the axion mass, $10^{-6}\mathrm{eV}\lesssim m_a\lesssim 10^{-3}\mathrm{eV}$. Finally, we comment on implications of these studies for the axion search experiments, including microwave cavity and the Orpheus experiments.

   hep-phastro-ph.COnucl-thEPJ Web Conf.(2017)·4 citations
7. 07*

   Search for Heavy Stops with Merged Top-Jets

   Yang Bai🇺🇸 · Joshua Berger🇺🇸 · James Osborne🇺🇸 · Ben A. Stefanek🇺🇸

   We study an interesting region of phase space at the LHC for pair-produced stops decaying into hadronic top quarks and light neutralinos. After imposing a sizeable cut on the missing transverse energy, which is the key variable for reducing backgrounds, we have found that the two hadronic tops are likely to merge into a single fat jet. We develop a jet-substructure-based strategy to tag the two merged top-jets and utilize the MT2 variable to further reduce the backgrounds. We obtain about a 50% increase to the ratio of the signal over background and a mild increase on the signal discovery significance, based on a signal with a 1.2 TeV stop and a 100 GeV neutralino, for the 13 TeV LHC with 100 fb${}^{-1}$. The general event kinematics could also occur and be explored for other new physics signatures with large missing transverse energy.

   hep-phhep-exPRD(2017)·3 citations
8. 08*

   $Z$ boson mediated dark matter beyond the effective theory

   John Kearney🇺🇸 · Nicholas Orlofsky🇺🇸 · Aaron Pierce🇺🇸

   Direct detection bounds are beginning to constrain a very simple model of weakly interacting dark matter---a Majorana fermion with a coupling to the $Z$ boson. In a particularly straightforward gauge-invariant realization, this coupling is introduced via a higher-dimensional operator. While attractive in its simplicity, this model generically induces a large $\rho$ parameter. An ultraviolet completion that avoids an overly large contribution to $\rho$ is the singlet-doublet model. We revisit this model, focusing on the Higgs blind spot region of parameter space where spin-independent interactions are absent. This model successfully reproduces dark matter with direct detection mediated by the $Z$ boson, but whose cosmology may depend on additional couplings and states. Future direct detection experiments should effectively probe a significant portion of this parameter space, aside from a small coannihilating region. As such, $Z$-mediated thermal dark matter as realized in the singlet-doublet model represents an interesting target for future searches.

   hep-phPRD(2017)·54 citations
9. 09*

   Present Status of b -> s l+ l- Anomalies

   F. Mahmoudi🇫🇷 · T. Hurth🇩🇪 · S. Neshatpour🇮🇷

   We discuss the observed deviations in b -> s l+ l- processes from the Standard Model predictions and present global fits for the New Physics description of these anomalies. We further investigate the stability of the global fits under different theoretical assumptions and suggest strategies and a number of observables to clear up the source of the anomalies.

   hep-phNucl.Part.Phys.Proc.(2017)·22 citations
10. 10*

    Constraints on the CP-Violating MSSM

    A. Arbey🇫🇷 · J. Ellis🇬🇧 · R. M. Godbole🇮🇳 · F. Mahmoudi🇫🇷

    We discuss the prospects for observing CP violation in the MSSM with six CP-violating phases, using a geometric approach to maximise CP-violating observables subject to the experimental upper bounds on electric dipole moments. We consider constraints from Higgs physics, flavour physics, the dark matter relic density and spin-independent scattering cross section with matter.

    hep-phNucl.Part.Phys.Proc.(2017)·4 citations
11. 11*

    Global fits of scalar singlet dark matter with GAMBIT

    Jonathan M. Cornell (for the GAMBIT collaboration)🇨🇦

    The wide range of probes of physics beyond the standard model leads to the need for tools that combine experimental results to make the most robust possible statements about the validity of theories and the preferred regions of their parameter space. Here we introduce a new code for such analyses: GAMBIT, the Global and Modular BSM Inference Tool. GAMBIT is a flexible and extensible framework for global fits of essentially any BSM theory. The code currently incorporates direct and indirect searches for dark matter, limits on production of new particles from the LHC and LEP, complete flavor constraints from LHCb, LHC Higgs production and decay measurements, and various electroweak precision observables. Here we present an overview of the code's capabilities, followed by preliminary results from scans of the scalar singlet dark matter model.

    hep-phastro-ph.HEhep-exPoS(2016)·7 citations
12. 12*

    Impact of non-standard interactions on neutrino-nucleon scattering

    D.K. Papoulias🇬🇷 · T.S. Kosmas🇬🇷

    Non-standard neutrino-nucleon interaction is formulated and explored within the energy range of quasi-elastic scattering. In particular, the study focuses on the neutral-current elastic (anti)neutrino scattering off nucleons described by the exotic reactions ${\nu }_{\alpha }({\bar{\nu }}_{\alpha })+n\to {\nu }_{\beta }({\bar{\nu }}_{\beta })+n$ and ${\nu }_{\alpha }({\bar{\nu }}_{\alpha })+p\to {\nu }_{\beta }({\bar{\nu }}_{\beta })+p$, which provide corrections to the dominant Standard Model processes. In this context, it is shown that the required exotic nucleon form factors may have a significant impact on the relevant cross sections. Besides cross sections, the event rate is expected to be rather sensitive to the magnitude of the lepton-flavour violating parameters resulting in an excess of events. The overlap of non-standard interactions and strange quark contributions, in the region of few GeV neutrino energies, is also examined. The formalism is applied for the case of the relevant neutrino-nucleon scattering experiments (LSND, MiniBooNE, etc.) and motivates the notion that such facilities have high potential to probe NSI.

    hep-phAdv.High Energy Phys.(2016)·15 citations
13. 13*

    LHC Forward Physics

    K. Akiba · M. Akbiyik · M. Albrow · M. Arneodo · V. Avati · J. Baechler · O. Villalobos Baillie · P. Bartalini · J. Bartels · S. Baur · C. Baus · W. Beaumont and 175 other authors

    The goal of this report is to give a comprehensive overview of the rich field of forward physics, with a special attention to the topics that can be studied at the LHC. The report starts presenting a selection of the Monte Carlo simulation tools currently available, chapter 2, then enters the rich phenomenology of QCD at low, chapter 3, and high, chapter 4, momentum transfer, while the unique scattering conditions of central exclusive production are analyzed in chapter 5. The last two experimental topics, Cosmic Ray and Heavy Ion physics are presented in the chapter 6 and 7 respectively. Chapter 8 is dedicated to the BFKL dynamics, multiparton interactions, and saturation. The report ends with an overview of the forward detectors at LHC. Each chapter is correlated with a comprehensive bibliography, attempting to provide to the interested reader with a wide opportunity for further studies.

    hep-phhep-exJ.Phys.G(2016)·229 citations
14. 14*

    NLO predictions for SMEFT in the top-quark sector

    Cen Zhang🇺🇸

    Predictions for the Standard Model Effective Field Theory at the next-to-leading order accuracy in QCD, including parton-shower effects, have started to become available in the MadGraph5_aMC@NLO framework. In this talk we summarize some recent results for $t\bar{t}$, single top, $t\bar{t}Z/\gamma$, and $t\bar{t}H$ production channels at dimension six.

    hep-phhep-exPoS(2016)·0 citations
15. 15*

    Higher-orders in heavy quark processes within the LTD approach

    German F. R. Sborlini🇪🇸

    The computation of perturbative corrections to processes involving heavy quarks is crucial for the precision program of the LHC and future colliders. In this article, we describe a powerful approach to calculate higher-orders in QCD skipping the traditional subtraction method. Our proposal is based on the loop-tree duality (LTD) theorem, which allows to rewrite virtual contributions in terms of integrals over the real emission phase-space. Then, we proceed to combine both real and virtual contributions at the integrand level, obtaining regular expressions that can be numerically integrated in four space-time dimensions. In this way, we avoid dealing with complicated massive Feynman integrals and introducing infrared counter-terms. Some reference examples are explained, in order to exhibit the potential of our method.

    hep-phhep-thPoS(2016)·2 citations
16. 16*

    Prompt atmospheric neutrino flux

    Yu Seon Jeong🇰🇷 · Atri Bhattacharya🇧🇪 · Rikard Enberg🇸🇪 · C. S. Kim🇰🇷 · Mary Hall Reno🇺🇸 · Ina Sarcevic🇺🇸 · Anna Stasto🇺🇸

    We evaluate the prompt atmospheric neutrino flux including nuclear correction and $B$ hadron contribution in the different frameworks: NLO perturbative QCD and dipole models. The nuclear effect is larger in the prompt neutrino flux than in the total charm production cross section, and it reduces the fluxes by $10\%-30\%$ depending on the model. We also investigate the uncertainty using the QCD scales allowed by the charm cross section data from RHIC and LHC experiments.

    hep-phastro-ph.HEPoS(2016)·1 citation
17. 17*

    Leptonic mono-top from single stop production at LHC

    Guang Hua Duan🇨🇳 · Ken-ichi Hikasa🇯🇵 · Lei Wu🇨🇳 · Jin Min Yang🇨🇳 · Mengchao Zhang🇰🇷

    Top squark (stop) can be produced via QCD interaction but also the electroweak interaction at the LHC. In this paper, we investigate the observability of the associated production of stop and chargino, $pp\to {\tilde{t}}_1{\tilde{\chi }}_1^{-}$, in compressed electroweakino scenario at the 14 TeV LHC. Due to the small mass-splitting between the lightest neutralino (${\tilde{\chi }}_1^0$) and chargino (${\tilde{\chi }}_1^{-}$), such a single stop production can give a mono-top signature through the stop decay ${\tilde{t}}_1\to t{\tilde{\chi }}_1^0$. Focusing on the leptonic mono-top channel, we propose a lab-frame observable $\cos {\theta }_{b\ell }$ to reduce the SM backgrounds in virtue of a boosted top quark from the stop decay. We find that the single stop production can be probed at $2\sigma$ level at the HL-LHC for $m_{{\tilde{t}}_1}<760$ GeV and $m_{{\tilde{\chi }}_1^0}<150$ GeV.

    hep-phJHEP(2017)·16 citations
18. 18*

    Transverse double-spin asymmetries for electroweak gauge-boson production in high-energy polarized $p^{\uparrow }+p^{\uparrow }$ collisions

    Jacques Soffer🇺🇸 · Bernd Surrow🇺🇸 · Claude Bourrely🇫🇷

    We consider the production of $W$ and $Z/{\gamma }^{\ast }$ gauge bosons in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=510\text{mbox}GeV$ available at RHIC at BNL, operating at high luminosity. We stress the importance of measuring the transverse double-spin asymmetries $A_{TT}$, in connection with available transversely polarized beams with a high degree of polarisation. We will discuss some theoretical issues related to the predicted asymmetries. These studies are contrasted to the 2017 RHIC running operation of transversely polarized beams of mid-rapidity $W$ and $Z$ boson production at a center-of-mass energy of $\sqrt{s}=510$GeV along with long-term prospects beyond 2020 at RHIC.

    hep-ph1 citation
19. 19*

    Light Stops and Fine-Tuning in MSSM

    Ali Cici🇹🇷 · Zerrin Kirca🇹🇷 · Cem Salih Un🇹🇷

    We discuss the fine-tuning issue within the MSSM framework. Following the idea that the fine-tuning can measure effects of some missing mechanism, we impose non-universal gaugino masses at the GUT scalem and explore the low scale implications. We realize that the fine-tuning parametrized with Delta_EW can be as low as zero. We consider the stop mass with a special importance and focus on the mass scales as m_stop <=700 GeV, which are excluded by current experiments when the stop decays into a neutralino along with a top quark or a chargino along with a b quark. We find that the stop mass can be as low as about 200 GeV with Delta_EW ~ 50. We find that the solutions in this region can be exluded only up to 60% when stop decays into a neutralino-top quark, and 50% when it decays into a chargino-b quark pair. Setting 65% CL to be potential exclusion and 95% to be pure exclusion limit such solutions will be tested in near future experiments, which are conducted with higher luminosity. In addition to stop, the region with low fine-tuning and light stops predicts masses for the other supersymmetric particles such as m_sbottom >~ 600 GeV, m_stau >~ 1 TeV, m_chargino >~ 120 GeV. The details for the mass scales and decay rates are also provided by tables of benchmark points.

    hep-phEPJC(2018)·15 citations
20. 20*

    Theory overview on amplitude analyses with charm decays

    B. Loiseau🇫🇷

    This contribution about amplitude analyses in multibody hadronic charm decays deals with some attempts to introduce theoretical constraints. Different effective hadronic formalism approaches are mentioned. A recent work, based on a basic weak interaction process and a Chiral unitary model to account for the final state interaction, is described in details for the $f_0(980)$ production in $D_s^{+}\to {\pi }^{+}{\pi }^{+}{\pi }^{-}$ and $D_s^{+}\to {\pi }^{+}{K}^{+}{K}^{-}$ decays. Within the framework of the diagrammatic approach and flavor symmetry, a global analysis of two-body $D$ decays into a vector meson and a pseudoscalar meson is presented. A quasi-two-body QCD factorization model for $D$ decays into three mesons and its recent application to $D^0\to K_S^0{\pi }^{+}{\pi }^{-}$ is outlined. For processes with final-state pions and kaons and as an alternative to the sum of Breit-Wigner amplitudes, often used in experimental Dalitz-plot analyses, amplitude parametrizations, in term of unitary $\pi \pi$, $\pi K$ and $K\bar{K}$ form factors, are proposed. These parametrizations are derived from quasi-two-body factorization models.

    hep-phPoS(2016)·6 citations
21. 21*

    Phases of dense matter with holographic instantons

    Florian Preis🇦🇹 · Andreas Schmitt🇬🇧

    We discuss nuclear matter and the transition to quark matter in the decompactified limit of the Sakai-Sugimoto model. Nuclear matter is included through instantons on the flavor branes of the model. Our approximation is based on the flat-space solution, but we allow for a dynamical instanton width and deformation and compute the energetically preferred number of instanton layers in the bulk as a function of the baryon chemical potential. We determine the regions in parameter space where the binding energy of nuclear matter is like in QCD, and compute the phase diagram in the plane of temperature and chemical potential.

    hep-phhep-thnucl-thEPJ Web Conf.(2017)·7 citations
22. 22*

    Constraining CPT-odd nonminimal interactions in the Electroweak sector

    Victor E. Mouchrek-Santos🇧🇷 · Manoel M. Ferreira Jr🇧🇷

    In this work, we propose two possibilities of CPT-odd and Lorentz-violating (LV) nonminimal couplings in the Electroweak sector. These terms are gauge-invariant and couple a fixed 4-vector to the physical fields of the theory. After determining the LV contributions to the electroweak currents, we reassess the evaluation of the decay rate for the vector mediators $W$ and $Z$. Using the experimental uncertainty in these decay rates, upper bounds of $1$ part in $10^{-15}$ (eV )${}^{-1}$ and $10^{-14}$ (eV )${}^{-1}$ are imposed on the magnitude of the proposed nonmimal interactions.

    hep-phhep-thPRD(2017)·25 citations
23. 23*

    Next-to-leading-order electroweak corrections to the production of four charged leptons at the LHC

    Benedikt Biedermann🇩🇪 · Ansgar Denner🇩🇪 · Stefan Dittmaier🇩🇪 · Lars Hofer🇪🇸 · Barbara Jager🇩🇪

    We present a state-of-the-art calculation of the next-to-leading-order electroweak corrections to ZZ production, including the leptonic decays of the Z bosons into ${\mu }^{+}{\mu }^{-}{\mathrm{e}}^{+}{\mathrm{e}}^{-}$ or ${\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$ final states. We use complete leading-order and next-to-leading-order matrix elements for four-lepton production, including contributions of virtual photons and all off-shell effects of Z bosons, where the finite Z-boson width is taken into account using the complex-mass scheme. The matrix elements are implemented into Monte Carlo programs allowing for the evaluation of arbitrary differential distributions. We present integrated and differential cross sections for the LHC at 13 TeV both for an inclusive setup where only lepton identification cuts are applied, and for a setup motivated by Higgs-boson analyses in the four-lepton decay channel. The electroweak corrections are divided into photonic and purely weak contributions. The former show the well-known pronounced tails near kinematical thresholds and resonances; the latter are generically at the level of $\sim -5\%$ and reach several $-10\%$ in the high-energy tails of distributions. Comparing the results for ${\mu }^{+}{\mu }^{-}{\mathrm{e}}^{+}{\mathrm{e}}^{-}$ and ${\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$ final states, we find significant differences mainly in distributions that are sensitive to the ${\mu }^{+}{\mu }^{-}$ pairing in the ${\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$ final state. Differences between ${\mu }^{+}{\mu }^{-}{\mathrm{e}}^{+}{\mathrm{e}}^{-}$ and ${\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$ channels due to interferences of equal-flavour leptons in the final state can reach up to $10\%$ in off-shell-sensitive regions. Contributions induced by incoming photons, i.e. photon-photon and quark-photon channels, are included, but turn out to be phenomenologically unimportant.

    hep-phhep-exJHEP(2017)·100 citations
24. 24*

    Electroweak precision constraints at present and future colliders

    Jorge de Blas🇮🇹 · Marco Ciuchini🇮🇹 · Enrico Franco🇮🇹 · Satoshi Mishima🇯🇵 · Maurizio Pierini🇨🇭 · Laura Reina🇺🇸 · Luca Silvestrini🇮🇹

    We revisit the global fit to electroweak precision observables in the Standard Model and present model-independent bounds on several general new physics scenarios. We present a projection of the fit based on the expected experimental improvements at future $e^{+}{e}^{-}$ colliders, and compare the constraining power of some of the different experiments that have been proposed. All results have been obtained with the HEPfit code.

    hep-phhep-exPoS(2017)·47 citations
25. 25*

    The light U boson as the mediator of a new force, coupled to a combination of Q, B, L and dark matter

    Pierre Fayet🇫🇷

    A new light gauge boson $U$ may have both vector and axial couplings. In a large class of theories however, the new $U(1)$ current $J_F^{\mu }$ naturally combines with the weak neutral current $J_{Z_{\mathrm{sm}}}^{\mu }$, both parity-violating, into a vectorial current $J_U^{\mu }$, combination of the $B,L$ and electromagnetic currents with a possible dark matter current. $U^{\mu }$ may be expressed equivalently as $\cos \xi C^{\mu }+\sin \xi Z_{\mathrm{sm}}^{\mu }$ ("mixing with the $Z$") or $(1/\cos \chi ){\hat{C}}^{\mu }+\tan \chi A^{\mu }$ ("mixing with the photon"), with $\hat{C}$ coupled to $B,L$ and dark matter. The $U$ boson may be viewed as a generalized dark photon, coupled to SM particles through $Q_U=Q+{\lambda }_{B}B+{\lambda }_i{L}_i$, with strength $g"\cos \xi {\cos }^2\theta =e\tan \chi$. "Kinetic mixing" terms, gauge invariant or not, simply correspond to a description in a non-orthogonal field basis (rather than to a new physical effect), with the dark photon in general also coupled to $B$ and $L$. In a grand-unified theory $Q_U^{\mathrm{gut}}=Q-2(B-L)$ at the GUT scale for SM particles, invariant under the $SU(4)$ electrostrong symmetry group, with a non-vanishing $ϵ=\tan \chi$ already present at the GUT scale, leading to $Q_U\simeq Q-1.64(B-L)$ at low energy. This also applies, for a very light or massless $U$ boson, to a new long-range force, which could show up through apparent violations of the Equivalence Principle.

    hep-phhep-exEPJC(2017)·76 citations
26. 26*

    Revising the $f_1(1420)$ resonance

    V. R. Debastiani🇪🇸 · F. Aceti🇪🇸 · Wei-Hong Liang🇨🇳 · E. Oset🇪🇸

    We have studied the production and decay of the $f_1(1285)$ into $\pi a_0(980)$ and $K^{\ast }\bar{K}$ as a function of the mass of the resonance and find a shoulder around 1400 MeV, tied to a triangle singularity, for the $\pi a_0(980)$ mode, and a peak around 1420 MeV with about 60 MeV width for the $K^{\ast }\bar{K}$ mode. Both these features agree with the experimental information on which the $f_1(1420)$ resonance is based. In addition, we find that if the $f_1(1420)$ is a genuine resonance, coupling mostly to $K^{\ast }\bar{K}$ as seen experimentally, one finds unavoidably about a 20\% fraction for $\pi a_0(980)$ decay of this resonance, in drastic contradiction with all experiments. Altogether, we conclude that the $f_1(1420)$ is not a genuine resonance, but the manifestation of the $\pi a_0(980)$ and $K^{\ast }\bar{K}$ decay modes of the $f_1(1285)$ at higher energies than the nominal one.

    hep-phPRD(2017)·47 citations
27. 27*

    Investigation on Finsler geometry as a generalization to curved spacetime of Planck-scale-deformed relativity in the de Sitter case

    Iarley P. Lobo🇮🇹 · Niccoló Loret🇭🇷 · Francisco Nettel🇮🇹

    In recent years, Planck-scale modifications to particles' dispersion relation have been deeply studied for the possibility to formulate some phenomenology of Planckian effects in astrophysical and cosmological frameworks. There are some indications [arXiv:gr-qc/0611024] that Finsler geometry can provide some generalization of Riemannian geometry which may allow to account for non-trivial (Planckian) structure of relativistic particles' configuration space. We investigate the possibility to formalize Planck-scale deformations to relativistic models in curved spacetime, within the framework of Finsler geometry. We take into account the general strategy of analysis of modifications of dispersion relations in curved spacetimes proposed in [arXiv:1507.02056], generalizing to the de Sitter case the results obtained in [arXiv:1407.8143], for deformed relativistic particle kinematics in flat spacetime using Finsler formalism.

    ↳ gr-qchep-phhep-thPRD(2017)·43 citations
28. 28*

    Renormalization Group independence of Cosmological Attractors

    Jacopo Fumagalli🇳🇱

    The large class of inflationary models known as $\alpha$- and $\xi$-attractors gives identical cosmological predictions at tree level (at leading order in inverse power of the number of efolds). Working with the renormalization group improved action, we show that these predictions are robust under quantum corrections. This means that for all the models considered the inflationary parameters $(n_s,r)$ are (nearly) independent on the Renormalization Group flow. The result follows once the field dependence of the renormalization scale, fixed by demanding the leading log correction to vanish, satisfies a quite generic condition. In Higgs inflation (which is a particular $\xi$-attractor) this is indeed the case; in the more general attractor models this is still ensured by the renormalizability of the theory in the effective field theory sense.

    ↳ hep-thastro-ph.COgr-qchep-phPLB(2017)·32 citations
29. 29*

    Self-consistent Spectral Functions in the $O(N)$ Model from the FRG

    Nils Strodthoff🇺🇸

    We present the first self-consistent direct calculation of a spectral function in the framework of the Functional Renormalization Group. The study is carried out in the relativistic $O(N)$ model, where the full momentum dependence of the propagators in the complex plane as well as momentum-dependent vertices are considered. The analysis is supplemented by a comparative study of the Euclidean momentum dependence and of the complex momentum dependence on the level of spectral functions. This work lays the groundwork for the computation of full spectral functions in more complex systems.

    ↳ hep-thcond-mat.quant-gashep-phPRD(2017)·40 citations
30. 30*

    Recent progress in anisotropic hydrodynamics

    Michael Strickland🇺🇸

    The quark-gluon plasma created in a relativistic heavy-ion collisions possesses a sizable pressure anisotropy in the local rest frame at very early times after the initial nuclear impact and this anisotropy only slowly relaxes as the system evolves. In a kinetic theory picture, this translates into the existence of sizable momentum-space anisotropies in the underlying partonic distribution functions, <p_L^2> << <p_T^2>. In such cases, it is better to reorganize the hydrodynamical expansion by taking into account momentum-space anisotropies at leading-order in the expansion instead of as a perturbative correction to an isotropic distribution. The resulting anisotropic hydrodynamics framework has been shown to more accurately describe the dynamics of rapidly expanding systems such as the quark-gluon plasma. In this proceedings contribution, I review the basic ideas of anisotropic hydrodynamics, recent progress, and present a few preliminary phenomenological predictions for identified particle spectra and elliptic flow.

    ↳ nucl-thhep-phEPJ Web Conf.(2017)·9 citations
31. 31*

    Dynamics of semi-superfluid fluxtubes in color-flavor locked quark matter

    Mark G. Alford🇺🇸 · Andreas Windisch🇺🇸

    At very high densities, as for example in the core of a neutron star, matter may appear in the color-flavor locked (CFL) phase, which is a superfluid. This phase features topologically stable vortex solutions, which arise in a spinning superfluid as localized configurations carrying quanta of angular momentum. Despite the topological stability of these vortices they are not the lowest energy state of the system at neutron star densities and decay into triplets of semi-superfluid fluxtubes. In these proceedings we report on the progress of our numerical study in the Ginzburg-Landau approach, where we investigate lattices of semi-superfluid fluxtubes. The fluxtubes are obtained through controlled decay of global vortex configurations in the presence of a gauge field. Understanding the dynamics of semi-superfluid string configurations is important in the context of angular momentum transfer from a quark matter core of a neutron star beyond the core boundary, since not vortex-, but fluxtube pinning seems to be the relevant mechanism in this scenario.

    ↳ nucl-thastro-ph.HEhep-phEPJ Web Conf.(2017)·0 citations
32. 32*

    Detecting the Neutrinos Mass Hierarchy from Cosmological Data

    Lixin Xu🇨🇳 · Qing-Guo Huang🇨🇳

    We propose a new parameterization to measure the neutrino mass hierarchy, namely $\Delta =(m_3-m_1)/(m_1+m_3)$ which is dimensionless and varies in the range $[-1,1]$. Taking into account the results of neutrino oscillation experiments, $\Delta$ is the unique parameter for determining all the masses of neutrinos, and a positive (negative) sign of $\Delta$ denotes the normal (inverted) mass hierarchy. Adopting the currently available cosmic observations, we find that the normal mass hierarchy is slightly favored, and the mass of lightest neutrino is less than $0.030$ eV for the normal mass hierarchy and $0.024$ eV for the inverted mass hierarchy at $95\%$ confidence level.

    ↳ astro-ph.COhep-phSCPMA(2018)·55 citations
33. 33*

    First experience with classical-statistical real-time simulations of anomalous transport with overlap fermions

    P. V. Buividovich🇩🇪 · S. N. Valgushev🇩🇪

    We present first results of classical-statistical real-time simulations of anomalous transport phenomena with overlap fermions. We find that even on small lattices overlap fermions reproduce the real-time anomaly equation with much better precision than Wilson-Dirac fermions on an order of magnitude larger lattices. The difference becomes much more pronounced for quickly changing electromagnetic fields, especially if one takes into account the back-reaction of fermions on electromagnetism. As test cases, we consider chirality pumping in parallel electric and magnetic fields and mixing between the plasmon and the Chiral Magnetic Wave.

    ↳ hep-lathep-phhep-thPoS(2016)·14 citations
34. 34*

    From gluon topology to chiral anomaly: Emergent phenomena in quark-gluon plasma

    Jinfeng Liao🇺🇸

    Heavy-ion collision experiments at RHIC and the LHC have found a new emergent phase of QCD, a strongly coupled quark-gluon plasma (sQGP) that is distinctively different from either the low temperature hadron phase or the very high temperature weakly coupled plasma phase. Highly nontrivial emergent phenomena occur in such sQGP and two examples will be discussed in this contribution: the magnetic component of sQGP that stems from topologically nontrivial configurations in the gluon sector; and the anomalous chiral transport that arises as macroscopic manifestation of microscopic chiral anomaly in the quark sector. For both examples, their important roles in explaining pertinent heavy-ion data will be emphasized.

    ↳ nucl-thhep-phhep-thnucl-exJ.Phys.Conf.Ser.(2017)·1 citation

* 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.