Advances in High Energy Physics and Cosmology

21 Mar 2018, 16:00 → 23 Mar 2018, 16:20 Europe/London

University of Southampton

Simon King (University of Southampton), Sonali Mohapatra (University of Sussex), Jack Setford (University of Sussex)

This student lead conference aims to bring together students from all GRADnet nodes to view and deliver talks on a variety of topics including dark matter, gravitational waves and cosmology. It will take place at the University of Southampton on 21-23 March 2018.

Students from GRADnet nodes will be fully funded for travel and accommodation. In addition, lunch, coffee and a conference dinner will also be provided.

We encourage abstract submissions from PhD students and post-doctoral researchers for oral and poster presentations. To submit your abstract, please register and then fill out the form under ‘Call for Abstracts’.

Wednesday, 21 March

16:00 Arrival

Thursday, 22 March

08:00 Breakfast (B38 Terrace Restaurant)

09:00 Registration (Murray Lecture Theatre Complex)

1 Holographic Cosmology

Speaker: Kostas Skenderis (University of Amsterdam)

2 Lattice Holographic Cosmology

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Speaker: Matthew Mostert (University of Southampton)

Mostert-MB_Lattice-Holographic-Cosmology.pdf

10:40 Coffee Break

3 Lattice QCD

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Speaker: James Richings (University of Southampton)

PionScatteringandLatticeQCD_v3.pdf

4 Searches for NMSSM Signatures with Low Missing Transverse Energy at the LHC

We examine scenarios in the Next to Minimal Supersymmetric Standard Model where pair-produced squarks and gluinos decay via two cascades, each ending in a stable neutralino LSP and a standard model Higgs with the mass gaps in the decay such that the Missing Transverse Energy is very small. Performing two-dimensional parameter scans and focusing on the hadronic h→$b\bar{b}$ decay giving a $b\bar{b}b\bar{b}$ + $E_{T}^{\text{miss}}$ final state we then explore the sensitivity of a current CMS $\alpha_{T}$-based general-purpose jets+$E_{T}^{\text{miss}}$ analysis to such scenarios with a view to developing novel search approaches in the near future.

Speaker: Alexander Titterton (University of Bristol (GB))

5 Renormalisation group fixed points and physics at highest energies

Some recent developments in the understanding of particle theories controlled by ultraviolet fixed points.

Speaker: Mr Andrew Bond (University of Sussex)

andy_bond_soton18.pdf

6 Dimension-8 operators in Higgs physics

I will describe the process by which one can derive the full set of dimension-8 bosonic operators involving Higgses and gauge bosons. I will then discuss the implications of these operators on current measurements and bounds on dimension-6 Wilson coefficients.

Speaker: Jack Setford (University of Sussex)

Dimension-8 operators in Higgs physics.pdf

12:30 Lunch

7 Dark Matter

Speaker: Dr Stephen West (Royal Holloway, University of London)

8 Probing the nature of Dark Matter at the ILC

We analyse the potential of the proposed international linear collider to detect Dark Matter (DM) and determine its properties. In many models stability of Dark Matter particles D is ensured by conservation of a new quantum number referred to as D-parity. Our models also contain charged D-odd particles $D^{\pm}$ with the same spin as D. In this work, we study two minimal consistent models corresponding to scalar and fermionic DM. The first of which is the inert higgs doublet model (I2HDM), which is a $Z_2$ symmetric Two Higgs Doublet Model, with the lightest neutral scalar being identified as D. The latter contains an SU(2) doublet of vector-like Dirac fermions, and an additional neutral singlet fermion. In this model, D is a mixture of neutral fermion singlet and doublet. For minimal fermionic DM, we perform an analysis of constraints of the parameter space, coming from DM relic density, DM direct detection, and collider. We propose a method to determine the mass of DM and distinguish its spin, in the process $$e^+e^- \to D^+D^- \to DDW^+W^-\ to DD (q\bar{q})(\ell\nu)$ with a signature dijet + $\mu$ (or $e$) + missing mass.

Speaker: Daniel Locke (University of Southampton)

DM-ILC_Presentation.pdf

9 Fast simulations of dark matter structure formation with modified gravity and massive neutrinos.

I will briefly introduce the need for fast, approximate tools for cosmological simulations of dark matter structure formation, before talking about how we have implemented both modified gravity and massive neutrinos into the fast, approximate simulation tool $\tt{COLA}$.

I will present results produced by this extended version of $\tt{COLA}$ and explain how a potential degeneracy between the enhancement of structure formation due to modified gravity and suppression of structure formation due to massive neutrinos can make it difficult to distinguish between $\Lambda$CDM and modified gravity in observables such as the matter power spectrum.

Speaker: Mr Bill Wright (Institute of Cosmology and Gravitation, University of Portsmouth)

BillWrightSEPnetConference.pdf.pdf

15:00 Coffee Break

10 Leptogenesis and BSM physics

Speaker: Pasquale Di Bari (University of Southampton)

GRADNETCONF.pdf

11 Dark Matter indirect detection at Neutrino Telescopes: a multi-messenger approach

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Speaker: Dr Marco Chianese (University of Southampton)

SouthamptonChianese.pdf

12 Predicting the Right-Handed Neutrino Masses From the Littlest Seesaw and Leptogenesis

The Littlest Seesaw model based on two right-handed neutrinos with constrained Yukawa couplings provides a highly predictive description of neutrino masses and PMNS mixing parameters. If realised at high energies there will be renormalisation group corrections to the low energy predictions, which depend on the right-handed neutrino masses. We perform a $\chi^2$ analysis to determine the right-handed neutrino masses from a four-parameter fit to the low energy neutrino parameters, also eventually taking into account leptogenesis.

Speaker: Mr Sam Rowley (University of Southampton)

Littlest_Seesaw_AHEPC_ver0.4.pdf

13 Quantum diffusion during inflation and primordial black holes

I will explain how primordial black holes can form from perturbations seeded during inflation and how their abundance can be calculated in the framework of stochastic inflation. This formalism incorporates quantum backreaction of the small-wavelength fluctuations on the large distances dynamics of the Universe. If quantum corrections are small, the probability distribution of density fluctuations is well approximated by a Gaussian. If they are large, the PDF has a different profile with a longer tail and leads to constraints different from the ones usually derived.

Speaker: Mr Chris Pattison (ICG)

Chris_Pattison_quantum_diff_soton.pdf

14 Using infinite derivative gravity to resolve singularities

Infinite derivative gravity adds terms which make gravity weaker at short distances, allowing us the possiblity of avoiding the singularities which plague General Relativity. I will discuss both linearised perturbations to the flat metric and bouncing FRW cosmologies.

Speaker: James Edholm

SEPN new.pdf

SEPN new.pptx

15 Conformal window of asymptotic safety

The conformal window of a general class of gauge theories featuring a weakly coupled UV fixed point is investigated at next-to-next-to-leading order and found to lie completely within the domain of perturbation theory. Constraints are derived in various approximations, finding that vacuum instability yields the tightest constraint at NNLO.

Speaker: Gustavo Medina Vazquez (University of Sussex)

UVconformalwindow_sepnet_conference.pdf

16 Interacting vacuum dark energy

The standard model of cosmology, LCDM, suffers from both theoretical and observational problems that motivate alternative theories of dark energy. One such class of theories are interacting dark energy models. In my talk, I will give an overview of the problems with LCDM and discuss the interacting vacuum scenario, in which the time-varying vacuum energy is allowed to interact with dark matter. I will explain how this interaction can be reconstructed from and constrained by observational data and present some preliminary results.

Speaker: Ms Natalie Hogg

nbh_soton.pptx

19:00 Conference Dinner (B38 Terrace Restaurant)

Friday, 23 March

17 Testing gravity with black holes and gravitational waves

Speaker: Dr Helvi Witek

Talk_GradNet_March2018.pdf

18 Conformally Coupled General Relativity

Gravity model developed in the series of papers Grav.Cosmol. 15 (2009) 199-212; Phys.Lett. B691 (2010) 230-233; Gen.Rel.Grav. 44 (2012) 2745-2783 is revisited. Model is based on Ogievetsky theorem that specifies structure of general coordinate transformation group. The theorem is implemented in the context of Noether theorem with the use of nonlinear representation technique. Quantization is performed with the use of reparametrization-invariant time and ADM foliation techniques. Basic quantum features of the models are discussed.

Speaker: Mr Boris Latosh (University of Sussex)

Latosh_23_march.pdf

19 Rapid response gravitational wave follow-up with the PIRATE robotic telescope

In the last two years since LIGO discovered the first gravitational waves, the field of gravitational wave astronomy has advanced rapidly. In the last observing run (O2) LIGO detected two more binary black hole mergers and with the help of Virgo, was also able to detect gravitational waves from a binary neutron star merger. This event was a landmark discovery because in addition to gravitational waves there was an electromagnetic (EM) counterpart discovered less than 12 hours later, which turned out to be the first in ~250 EM observations that followed, making this the most widely observed astronomical event in history. The large majority of these observations were performed by ground based optical telescopes, and it was these telescopes that have performed similar tasks in every other LIGO alert in O2; by searching the night sky for an optical counterpart to the gravitational wave signals. The PIRATE robotic telescope, owned by The Open University but located in Tenerife, took part in some of these follow-up searches and was able to utilize its robotic nature to perform rapid follow-up observations as soon as an alert was received.

Speaker: Dean Roberts

Dean Roberts-OU.pdf

Dean Roberts-OU.pptx

10:30 Coffee Break

20 Semi-empirical techniques to unveil the properties of both galaxies and their host dark matter halos

Speaker: Dr Francesco Shankar

12:05 Lunch

21 Neutrinoless Double Beta Decay and the Baryon Asymmetry of the Universe

I will discuss the impact of the observation of neutrinoless double beta decay on the washout of lepton number in the early universe. Neutrinoless double beta decay can be triggered by a large number of mechanisms that can be encoded in terms of SM effective operators which violate lepton number. Such operators, or the underlying UV processes would also be responsible for the washout of an asymmetry in the lepton number in the early universe. Combined with SM sphaleron transitions, this would render many baryogenesis mechanisms at higher scales ineffective. I will highlight potential caveats to this argument, and the role of high energy colliders.

Speaker: Dr Frank Deppisch (University College London)

22 Gravitational Waves and Compact Binaries

Speaker: Christopher Berry

14:50 Coffee Break

23 Graviataional Waves from Phase Transitions in the Early Universe

Speaker: Mark Hindmarsh (University of Sussex)