The Northern Number Theory Seminar is a joint research seminar in number theory. It links the number theory research groups of Durham, Manchester, Nottingham, Sheffield and York.
We expect to meet twice per year. The seminar is funded by the LMS Grant Scheme 3.
The local organisers are:
 Durham: Thanasis Bouganis
 Manchester: Christopher Frei
 Nottingham: Christian Wuthrich
 Sheffield: Haluk Şengün
 York: Sanju Velani
Next Meeting
The next meeting is not yet scheduled but we expect one more meeting before summer 2020.
Past Meetings
The third meeting was held in York on Tuesday, October 15, 2019.
Schedule
All talks were in Topos (024B – next to the coffee room) on the ground floor of James College on the University of York Campus West. See below for a description of how to get there.
 1:30 Emma Bailey (Bristol)
 2:45 Pablo Shmerkin (T. Di Tella University and CONICET)
 4:30 Patrice Philippon (Institute de Mathématiques de Jussieu))
Title and abstracts
Emma Bailey: Moments of moments
I will motivate and present results concerning moments of moments of the Riemann zeta function alongside those of characteristic polynomials of random unitary matrices. The study of moments of moments has been furthered through connections with probability, combinatorics, and representation theory. This is joint work with Jon Keating.
Pablo Shmerkin: Multiplying by 2 and by 3: old conjectures and new results
In the 1960s, H. Furstenberg proposed a series of conjectures which, in different ways, aim to capture the heuristic principle that "expansions in different bases have no common structure". I will discuss a sample of these conjectures, some which remain open and some which have been established in recent years. These problems lie at the intersection of Ergodic Theory and Fractal Geometry, but no previous background on either area will be assumed.
Patrice Philippon: Around two problems of Hardy
Let \(\alpha>1\) and \(\lambda\) be real numbers. About a century ago, Hardy asked: "In what circumstances can it be true that the distance of \(\lambda \alpha^n\) to the nearest integer tends to \(0\) as \(n\) goes to \(\infty\)?". This question is still open. We will present some advances in this topic and around a related problem of Mahler, in the case \(\alpha\) is algebraic. This is joint work with Purusottam Rath.
The second meeting was held in Nottingham on Wednesday, May 15, 2019.
Schedule
All talks were in room C04 of the Physics building. See below for a description of how to get there.
 11am NilsPeter Skoruppa (Siegen)
 2pm Rachel Newton (Reading)
 3:30pm Robert Evans (King's College, London)
Title and abstracts
NilsPeter Skoruppa: A short proof of the Macdonald identities
We present a new and short proof of the wellknown Macdonald identities. The proof is rather selfcontained since it uses merely some easy combinatorial arguments, a basic (though subtle) geometrical fact about root systems and a bit of 'modular forms magic' (presented in the language of Jacobi forms). The proof suggests the possibility that there might be more, not yet dicovered Macdonald type identities and a method to systematically search for such. We shall discuss the algorithmic problems and computational complexity connected to such a search. Finally we mention some applications of the Macdonald identities to elliptic curves over the rationals.
Rachel Newton: Number fields with prescribed norms
Let \(G\) be a finite abelian group, let \(k\) be a number field, and let \(x\) be an element of \(k\). We count Galois extensions \(K/k\) with Galois group \(G\) such that \(x\) is a norm from \(K/k\). In particular, we show that such extensions always exist. This is joint work with Christopher Frei and Daniel Loughran.
Robert Evans: Factorising BSD: Artin twists of elliptic curves
I shall discuss the possible existence of a BSDtype formula for elliptic curves twisted by Artin representations. We will see that expected properties of Lfunctions give rise to some surprising arithmetic predictions for elliptic curves. This is joint work with Vladimir Dokchitser and Hanneke Wiersema.
The first meeting was held in Sheffield on Wednesday, February 20, 2019.
Schedule
All talks were in room J11 on the Jfloor of the Hicks building. See below for a description of how to get there.
 11am Farrell Brumley (Paris 13)
 2pm Andreea Mocanu (Nottingham)
 4pm Clark Barwick (Edinburgh)
Title and abstracts
Farrell Brumley: Concentration properties of theta lifts
I will present some results on the concentration properties of automorphic forms obtained through the theta correspondence. Among other things, the method relies on a distinction principle for these lifts, which detect their functorial origin via the non vanishing of orthogonal periods. The examples we treat are in higher rank, and shed light on a purity conjecture of Sarnak. This is joint work with Simon Marshall.
Andreea Mocanu: Newform theory for Jacobi forms of lattice index
I will give a brief introduction to Jacobi forms, including some examples and their relation to other types of modular forms. After that, I will discuss some of the ingredients that go into developing a theory of newforms for Jacobi forms of lattice index, namely Hecke operators, level raising operators and orthogonal groups of discriminant modules.
Clark Barwick: Primes, knots, and exodromy
Half a century ago, Barry Mazur and David Mumford suggested a remarkable dictionary between prime numbers and knots. I will explain how the story of exodromy permits one to make this dictionary precise, and I will describe some applications.
Travel
Here a list of how to get to the meetings.
Nottingham

There are trams leaving from Nottingham train station (go upstairs) every 7 minutes.
You want a tram in the direction of Toton Lane; get off at the University of Nottingham stop.
You need to buy a ticket from the machine before you get on the tram. The trip takes about 15 minutes.
The Maths building is number 20 on the campus map. Talks are usually held in the Physics building, opposite the Maths building, number 22 on the map. The tram stop is the green circle on the map near the South Entrance. A nice place for lunch is the Lakeside Arts cafe (number 49 on the map, near the lake and tram stop) or the staff club (number 8). Sheffield

The School of Mathematics and Statistics is in the Hicks Building which is building 121 on this map
You can also look at this map from the train station, but be aware that the walking route to the Hicks building is not obvious.
If you are arriving by train, the easiest way to get to the Hicks Building is by taking the tram. There is a tram stop right behind the train station. You need to take the Blue Line Tram in the direction of "Malin Bridge". A ticket costs £1.70  you pay the conductor on the tram. It takes about 10 minutes to get to the "University of Sheffield" tram stop where you should get off. Cross over the road at the traffic lights at the front of the tram (not to be confused with crossing over the tram lines) and go UP the Leavygreave Rd. The entrance to the Hicks Building (a very tall building) will be in front of you. York
 The Department of Mathematics is in James College on the University of York Campus West (the original campus). It is C3 building 21 on this map. Click here to plan your journey. There are buses from the city centre and railway station approximately every 5 minutes during the day, and it takes around 20 minutes to reach the campus. If you are taking a taxi, ask to be dropped at the Roger Kirk Centre.
Expenses
If you have a UK bank account you can get reimbursements for travel by using this form. Otherwise ask me.
Then send the form and receipts (try to avoid having the machine swallow your train tickets when you exit the station, please) to
School of Mathematical Sciences
University of Nottingham
Nottingham NG7 2RD
The seminar is committed to making sure all parents working in mathematics should be able to attend our meetings without being hindered by childcare costs. The LMS has a Childcare Supplementary Grant Scheme that can be cover extra costs caused by attending the meeting. Further information about this scheme can be found on this LMS website. Some of the host Universities, like Nottingham University, also have their own scheme to help. Please ask any of the organisers.